[Phil_S]

Greetings. I received a suggestion that I might find help here at RAT
answering questions about winding an output transformer.

I have a pair of small SE OT's. I don't know the origin. The came to me on
a derelict chassis from eBay. I harvested them and set the aside. The
other night, I thought I run some low voltage through to discover the turns
ratio. While doing that, there was a spark at one of the leads and I
promptly shut down the test. My instinct was to Ohm the windings to see if
they were OK or if I let the smoke out. Unfortunately, the meter read 265K,
so I concluded the tranny was toast, which lead me to the impulse to open it
up. Later, I discovered the meter was toast and the tranny was probably OK.
Anyhow, I had already unwound the primary (100 or 101 turns) and opened the
tape on the secondary, damaging and then removing about 60 turns in the
process.

I am hoping I can rewind the secondary for a SE 4.5W or 5W guitar amp --
your typical 6V6 Fender Champ and the like. I've done quite a bit of
reading and I'm thinking this can be done by hand if the primary is
suitable. I've gathered up all sorts of information, made calculations, and
whatnot, but feel that I would benefit from running this by someone who has
actually done this and has a better understanding than I do. Remember, this
is a for a guitar amp, with the relevant frequency range of about 82 - 5000
Hz.

Since I know the secondary turns, assuming 100, I ran the low voltage test
on the twin of the OT I took apart. I think the twin (still intact) has
3423 turns. Subtracting 60, the victimized OT has 3363 primary turns left.

I've been trying to determine the wire gauge on the primary without a proper
tool to do it. Using the scrap, I am getting about 3.6z on 63" of wire.
I've got 642 ohms left on the primary winding, suggesting 11,235". At about
4" per turn, that's about 2800 turns. I go with the higher number from the
electrical test, but I think this is reasonable confirmation. I also found
a chart stating 54.97 ohms per 1000" for 38 AWG. If I have 12,000" then 12
* 55 = 660 ohms, and I have 642 ohms. So, I believe the wire is 38 AWG. Is
this heavy enough for a 5W OT? Please read on for the description of the
lams.

I'd like to wind a 4-8-16 ohm secondary. Assuming 3363 primary turns, and
5K: 4-8-16, I'm coming up with turns ratios of 35.4-25-17.7 and secondary
turns of 95-135-190, respectively. Is this the correct calculation?

I've got another chart that shows current capacity at 600 cm/Amp and 700
cm/Amp. I figure your typical Champ amp, where Va=350 and Ia=0.045 The
current ratio is the primary multiplied by the turns ratio? IOW, 45mA *
35.4 = 1.6A? The chart says 19 or 20 AWG secondary wire for this measure.
It seems on the heavy side to me, but I don't really know much about this.
What is the correct sizing of the secondary wire gauge?

The lams, the core area is 18mm x 19mm = 3.42cm2 = .52 sq in. The I's
measure 54mm x 9mm. The E's measure 54mm x 36mm. The spaces between the
E's are about 9mm x 27mm -- thats the space where the bobbin fits. The
stack is 19mm high, but you already know that from the core area measure.
Everything seems to fit nicely in multiple of 9mm, so I guess this is a
European tranny, though I am in the US. That is why I'm using metric
measures -- it seems to fit. I got rather confused trying to figure the
number of primary turns, but have concluded that 3400 turns is plenty. Any
objection/other thoughts?

I don't know what sort of lams these are. Any way to tell? Eyeballing it,
the 19mm stack is about 60 lams. I am not wanting to take them apart and
make a mess of them.

Lastly, the air gap. It's there undisturbed. I don't have any way of
measuring it. Im inclined to leave it. I my estimation, it is not as
thick as a piece of copier paper so maybe 0.05mm?

I'd be very grateful if someone will help me out here and get me pointed in
the right direction. If you think what I've got isn't appropriate for a 5W
amp, what then? Please suggest another output tube.

Thanks.

Phil

[Big Bad Bob]

Phil_S wrote:
Greetings. I received a suggestion that I might find help here at RAT
answering questions about winding an output transformer.

If you want a 'transformer winding' project, have fun. let everyone know
how it went.

otherwise...

Rather than trying to repair an output transformer I would consider looking
for an equivalent transformer on E-bay or Amazon and not bother playing with
surplus stuff. Old transformers might cook in a year or two (been there,
done that), and then you're desperately looking for a replacement after all
that work building the amp. An inexpensive off-the-shelf output transformer
may cost less than $50 if you look hard, will most likely perform better
than your specs, and shouldn't burn out for a very very very long time. And
you can stock spares easily, if you anticipate eventual failure.

[Patrick Turner]

On Nov 3, 12:44*pm, "Phil_S" wrote:
Greetings. *I received a suggestion that I might find help here at RAT
answering questions about winding an output transformer.

I have a pair of small SE OT's. I don't know the origin. *The came to me on
a derelict chassis from eBay. *I harvested them and set the aside. *The
other night, I thought I run some low voltage through to discover the turns
ratio. *While doing that, there was a spark at one of the leads and I
promptly shut down the test. *My instinct was to Ohm the windings to see if
they were OK or if I let the smoke out. *

Never ever trust your own inexperienced instint - usually you will
find yourself in trouble.

Unfortunately, the meter read 265K,
so I concluded the tranny was toast, which lead me to the impulse to open it
up. *

Impulsiveness is even worse than instictiveness.

Don't worry, I've been there....

Later, I discovered the meter was toast and the tranny was probably OK.
Anyhow, I had already unwound the primary (100 or 101 turns) and opened the
tape on the secondary, damaging and then removing about 60 turns in the
process.

I am hoping I can rewind the secondary for a SE 4.5W or 5W guitar amp -- *
your typical 6V6 Fender Champ and the like. *I've done quite a bit of
reading and I'm thinking this can be done by hand if the primary is
suitable. *I've gathered up all sorts of information, made calculations, and
whatnot, but feel that I would benefit from running this by someone who has
actually done this and has a better understanding than I do. *Remember, this
is a for a guitar amp, with the relevant frequency range of about 82 - 5000
Hz.

Since I know the secondary turns, assuming 100, I ran the low voltage test
on the twin of the OT I took apart. *I think the twin (still intact) has
3423 turns. *Subtracting 60, the victimized OT has 3363 primary turns left.

I've been trying to determine the wire gauge on the primary without a proper
tool to do it. *

Maybe you should invest in a mircrometer. There are nice digital read
out types available and then consult the wire tables for "grade 2"
magnetic winding wire with polyester-imide enamel which will tell you
the copper wire dia and overall dia with enamel, which is what you can
measure.

Using the scrap, I am getting about 3.6z on 63" of wire.
I've got 642 ohms left on the primary winding, suggesting 11,235". *At about
4" per turn, that's about 2800 turns. *I go with the higher number from the
electrical test, but I think this is reasonable confirmation. *I also found
a chart stating 54.97 ohms per 1000" for 38 AWG. *If I have 12,000" then 12
* 55 = 660 ohms, and I have 642 ohms. *So, I believe the wire is 38 AWG. *Is
this heavy enough for a 5W OT? *Please read on for the description of the
lams.

One 6V6 in SE beam tetrode mode needs Ea = Eg2 at +300Vdc max, and Ia
= 36mA.

RL required = 0.9 x Ea / Ia = 0.9 x 300 / 0.036 = 7,500 ohms.

If the secondary load was 7.5 ohms the ZR = 1,000:1, so TR = 31.6:1.

Primary winding wire resistance should be less than 375 ohms, and
secondary winding resistance should be less than 0.4 ohms.

Inductance of the primary with **correct air gap** should be 30Henrys
where the measurement of inductance is made with no secondary load and
using a 10 ohm R in series with primary and a voltage test signal
using 50Vrms at mains frequency.
Measure the small voltage across the 10R. Then current through
inductance = V / 10. Then measure voltage across inductance.
Reactance in ohms of primary inductance = V / I .

Inductance = Reactance / ( 6.28 x frequency of test signal ).




I'd like to wind a 4-8-16 ohm secondary. *Assuming 3363 primary turns, *and
5K: 4-8-16, I'm coming up with turns ratios of 35.4-25-17.7 and secondary
turns of 95-135-190, respectively. *Is this the correct calculation?

5,000 : 4 is a ZR = 1,250. TR = sq.rt ZR = 35.3 : 1.

If you have 3,363 P turns, then for 4 ohms you need 95 Sec turns.


I've got another chart that shows current capacity at 600 cm/Amp and 700
cm/Amp. *I figure your typical Champ amp, where Va=350 and Ia=0.045 *

Maximum Pda for 6V6 = 12Watts. With Ea = +350Vdc and Ia = 0.045A, Pda
= 15.75Watts and much too high, so please do try to arrange your
efforts to minimise the chance of smoke, rather than to maximise the
chance.

If you wanted RL = 5k, then you can figure out exactly what Ea and Ia
you can have.

Using an OPT with 10% winding losses, expect anode efficiency = 40%.

So if Pda = 12W, then expect 4.8W max.

PO = Va squared / RL.

4.8 = Va squared / 5,000,

So Va = 155Vrms = 219V peak which gives Ia peak swing 0.044 A.
Let Ia be 5% more than peak Ia swing = 0.46A.

If Pda = 12W, then Ea = Pda / Ia = 12 / 0.046 = +259Vdc.

current ratio is the primary multiplied by the turns ratio? *

yes.

IOW, 45mA *
35.4 = 1.6A? The chart says 19 or 20 AWG secondary wire for this measure.
It seems on the heavy side to me, but I don't really know much about this..
What is the correct sizing of the secondary wire gauge?

From my webpage at
http://www.turneraudio.com.au/se-output-trans-calc.htm

18. Calculate primary winding resistance, Rwp.

Rwp = ( Np x TL ) / ( 44,000 x Pdia x Pdia )
where 44,000 is a constant, and P dia is the copper dia from the wire
tables .......Rwp, ohms

From this you can derive the dia of the wire if you know the wanted
maximum winding resistance.

The lams, the core area is 18mm x 19mm = 3.42cm2 = .52 sq in.

You have a pair of very small OPTs which one might find in a low
quality radio set which were made in thousands and which employed a
6V6 audio output tube.



The I's
measure 54mm x 9mm. *The E's measure 54mm x 36mm. *The spaces between the
E's are about 9mm x 27mm -- that’s the space where the bobbin fits. *The
stack is 19mm high, but you already know that from the core area measure.
Everything seems to fit nicely in multiple of 9mm, so I guess this is a
European tranny, though I am in the US. *That is why I'm using metric
measures -- it seems to fit. *I got rather confused trying to figure the
number of primary turns, but have concluded that 3400 turns is plenty. *Any
objection/other thoughts?

If I were you I would get something better from Hammond, then you'd
save yourself all the trouble of mucking around with these little
trannies.

I don't know what sort of lams these are. *Any way to tell? *Eyeballing it,
the 19mm stack is about 60 lams. *I am not wanting to take them apart and
make a mess of them.

Lastly, the air gap. *It's there undisturbed. *I don't have any way of
measuring it. *I’m inclined to leave it. *I my estimation, it is not as
thick as a piece of copier paper so maybe 0.05mm?

The air gap may be about right, but I doubt you would have enough
primary inductance for good bass.

Larger heavier OPT from Hammond would be so much better, and because
you want such low power they will be fairly cheap.

Something made in the USA should be available.

Besides, you need to save the economy from going bust, so SPEND.

I know Obama and the Tea Party have their conflicting ideas which you
may or may not agree with.

I'd be very grateful if someone will help me out here and get me pointed in
the right direction. *If you think what I've got isn't appropriate for a 5W
amp, what then? *Please suggest another output tube.

If I were going for a 5 watt SE amp I would use a 6L6GC in SE triode
mode, and then
the primary load = ( Ea / Ia ) - ( 2x Ra ). Ra is the internal dynamic
anode resistance, about 2,000 ohms for 6L6 at Ia = 50mA.

The trioded 6L6 will give you a "firmer" sound with greater depth and
will be less "frizzy" without punch which typifies SE beam tetrodes
and pentodes. EL34 in triode is also excellent.

Patrick Turner.

Thanks.

Phil

[Phil_S]

Hi Flipper. Long time, no see! In between....

"flipper" wrote in message
...

On Tue, 2 Nov 2010 21:44:42 -0400, "Phil_S"
wrote:

Greetings. I received a suggestion that I might find help here at RAT
answering questions about winding an output transformer.

I have a pair of small SE OT's. I don't know the origin. The came to me on
a derelict chassis from eBay. I harvested them and set the aside. The
other night, I thought I run some low voltage through to discover the turns
ratio. While doing that, there was a spark at one of the leads and I
promptly shut down the test. My instinct was to Ohm the windings to see if
they were OK or if I let the smoke out. Unfortunately, the meter read
265K,
so I concluded the tranny was toast, which lead me to the impulse to open
it
up. Later, I discovered the meter was toast and the tranny was probably
OK.
Anyhow, I had already unwound the primary (100 or 101 turns) and opened the
tape on the secondary, damaging and then removing about 60 turns in the
process.

I am hoping I can rewind the secondary for a SE 4.5W or 5W guitar amp --
your typical 6V6 Fender Champ and the like. I've done quite a bit of
reading and I'm thinking this can be done by hand if the primary is
suitable. I've gathered up all sorts of information, made calculations,
and
whatnot, but feel that I would benefit from running this by someone who has
actually done this and has a better understanding than I do. Remember,
this
is a for a guitar amp, with the relevant frequency range of about 82 - 5000
Hz.

Since I know the secondary turns, assuming 100, I ran the low voltage test
on the twin of the OT I took apart. I think the twin (still intact) has
3423 turns. Subtracting 60, the victimized OT has 3363 primary turns left.

I've been trying to determine the wire gauge on the primary without a
proper
tool to do it. Using the scrap, I am getting about 3.6z on 63" of wire.
I've got 642 ohms left on the primary winding, suggesting 11,235". At
about
4" per turn, that's about 2800 turns. I go with the higher number from the
electrical test, but I think this is reasonable confirmation. I also found
a chart stating 54.97 ohms per 1000" for 38 AWG. If I have 12,000" then 12
* 55 = 660 ohms, and I have 642 ohms. So, I believe the wire is 38 AWG.
Is
this heavy enough for a 5W OT? Please read on for the description of the
lams.

I'd like to wind a 4-8-16 ohm secondary. Assuming 3363 primary turns, and
5K: 4-8-16, I'm coming up with turns ratios of 35.4-25-17.7 and secondary
turns of 95-135-190, respectively. Is this the correct calculation?

I've got another chart that shows current capacity at 600 cm/Amp and 700
cm/Amp. I figure your typical Champ amp, where Va=350

I presume that 350 is a typo. It should be 250V.

**No, we typically see the 6V6 run at 350V, not a typo. I know what the
spec sheet says. I suppose I didn't account for, when Va rises, Ia falls.
No matter, though. **

and Ia=0.045 The
current ratio is the primary multiplied by the turns ratio? IOW, 45mA *
35.4 = 1.6A?

45mA is the DC idle current. The signal can then swing from 0 to twice
idle so maximum RMS, at clipping, would be .707 of that, or 31.8mArms
(rounded). 4 Ohm secondary would then be 1.13Arms.

**Well, that's good news. At 1.13A, smaller wire size is in play. LOL, the
chart says I can use 21 AWG.**

You can confirm that with P=I^2R, which comes to 5 Watts in both cases
(ignoring winding losses).

The chart says 19 or 20 AWG secondary wire for this measure.
It seems on the heavy side to me, but I don't really know much about this.
What is the correct sizing of the secondary wire gauge?

Patrick will probably be by, and he's the tranny expert, so I'll leave
that to him.

**Yes, I see a pile of good instruction from him. It will probably take me
hours to comprehend it, but seems to be the guidance I was seeking.**

The lams, the core area is 18mm x 19mm = 3.42cm2 = .52 sq in. The I's
measure 54mm x 9mm. The E's measure 54mm x 36mm. The spaces between the
E's are about 9mm x 27mm -- thats the space where the bobbin fits. The
stack is 19mm high, but you already know that from the core area measure.
Everything seems to fit nicely in multiple of 9mm, so I guess this is a
European tranny, though I am in the US. That is why I'm using metric
measures -- it seems to fit. I got rather confused trying to figure the
number of primary turns, but have concluded that 3400 turns is plenty. Any
objection/other thoughts?

I don't know what sort of lams these are. Any way to tell? Eyeballing it,
the 19mm stack is about 60 lams. I am not wanting to take them apart and
make a mess of them.

Lastly, the air gap. It's there undisturbed. I don't have any way of
measuring it. Im inclined to leave it. I my estimation, it is not as
thick as a piece of copier paper so maybe 0.05mm?

I'd be very grateful if someone will help me out here and get me pointed in
the right direction. If you think what I've got isn't appropriate for a 5W
amp, what then?

From your description it sounds like it might have been a 5W 6V6, or
similar, OPT to begin with.

Please suggest another output tube.

Something wrong with a 6V6? What would you be shooting for in a
different tube?

**No, 6V6 is good. What I meant is, if this is a 2W OT, please suggest a
tube that will work with that. It appears I'll be OK, so we don't need to
go there.**

You can save cost, depending on what spare transformers you have lying
around, with oddball heater voltages.

If you want a smaller base then there are 9 pin 6V6 equivalents like
the 6CM6 or the 'car radio' 12AB5.

**Way cool, if they can be found.**

In 7 pin there's the equivalent (to 250V) 6AQ5 or 'car radio' 12AQ5.

**Yes, I have about 50 6AQ5's, thanks. It's probably my favorite power
tube.**

For the same plate load with more gain there's the 9-pin 6BQ5 or
equivalent (but different 9-pin basing) 6GK6.

**Yes, I put 6GK6 in my 18W, but, again, this is not for the contingency of
it being a 2W OT.**

Thanks.

Phil


Thanks for the help.

Phil

[Phil_S]

"Big Bad Bob" wrote in message
m...

Phil_S wrote:
Greetings. I received a suggestion that I might find help here at RAT
answering questions about winding an output transformer.

If you want a 'transformer winding' project, have fun. let everyone know
how it went.

otherwise...

**Yes, this is about fun with transformers. I could just buy one. I'm
curious.**

[Phil_S]

"Patrick Turner" wrote in message
...
snipped it all for brevity, content was fabulous

Patrick:
I didn't want to be presumptive. A friend said you hang out here. I
couldn't find your web pages. Unfortunately, there is another Patrick
Turner who plays US Pro Football. Searching turned up nothing. Thank you
for your thoughtful reply and for the link to your pages.

I appreciate your comments about not trusting inexperienced instinct;
impulsiveness is even worse. You don't know the half of it. This was one
of those days when I was just looking for an excuse to do something like
this. I've been dabbling in building guitar amplifiers for a number of
years. I've done about a dozen. Only the first one was from a kit, so I've
got reasonable amateur level experience. I still have much to learn. I'm a
curious person. As I said, I figured this was a cheap OT and it was an
opportunity to see what makes it tick. This is about fun with transformers.
I didn't imagine I'd get from this "project" a high quality OT. Even so,
for a guitar amp, I believe quality is a bit less of an issue. I don't need
20Hz at the low end or 20KHz at the top end.

As for the meter, I was really quite surprised to see that I'd toasted it.
It is a Triplett 9045, which is OK for a hobby meter and has stood by me
well for several years. I've got two more hand held meters and I just put
the old Fluke 8600A bench meter up for a battery charge. I'm sorry to see
that Triplett go. It seems to be working on everything but the Ohms.
shrug

Thanks also for some calculations, confirmations and corrections. This,
with your SE pages on the web should keep me busy for a while. I'm feeling
much better about being pointed in the right direction. I am hoping for the
simple satisfaction of making something that works. How well it works can
be a surprise. Some of the measurements will be difficult to make with a
limited amount of test equipment. I think you've given me the excuse I need
to get the digital caliper. This is an inexpensive tool and who doesn't
need another tool?

I can easily get a new tranny. That, as you've gathered, isn't the point.
This is an opportunity to learn something. I had trouble letting it pass me
by. You've pretty well confirmed my suspicions about the quality of what
I've got. I'm OK with it.

Finally, your suggestion about running a 6L6 as a triode is just wonderful!
I'm sitting on a box of a dozen Russian 6P3C (not the 6P3C-N), as well as a
few used real USA made 6L6 and 5881 tubes, and I've been looking for an
excuse to use them. This might be just the thing.

Best regards,
Phil

[Phil_S]

OK, I've got some "findings" that suggest I can't get from here to there.

1) For 6V6 at 4.8W, I really should be using 32 AWG. Further work suggests
the best case it that the existing primary wind is 37 AWG and more likely 38
AWG. This is too thin. The core area is small that calculations suggest is
needed.
2) The primary resistance for 3363 estimate turns is 643 ohms. Patrick says
it should be less than 375 ohms. This would probably be true for 32 AWG, I
estimate I'll need about 1000 ft, and that is 168 ohms (table value).
3) The remaining margin on the bobbin is about 3mm. If I did the calc
right, I've got room for about 90 turns of #20; I need 95 for a 4z winding.

Maybe I'm not "getting it" completely here. Maybe I've flubbed a few of the
numbers. Even so, the whole thing seems too small. I think maybe I've got
a 1-2W OT.

Maybe I can rewind this for half a 12AU7 -- maybe I can make a one tube amp?
Maybe a 12AU7 pre with a 6C4 output? I guess I'm hell bent on finding a use
for this piece of junk. Remember, fun with tubes and transformers -- the
process is as important as the product.

I'm looking to change the plan here. I think it is not going to work for a
6V6 or a 6AQ5.

Flipper, you asked about the wire chart. It's here at the end of this
article.
http://www.deerloverssite.org/TRANSFORMERS.html

Patrick Turner wrote the following:
"If you wanted RL = 5k, then you can figure out exactly what Ea and Ia you
can have.
Using an OPT with 10% winding losses, expect anode efficiency = 40%.
So if Pda = 12W, then expect 4.8W max.
PO = Va squared / RL.
4.8 = Va squared / 5,000,
So Va = 155Vrms = 219V peak which gives Ia peak swing 0.044 A.
Let Ia be 5% more than peak Ia swing = 0.46A.
If Pda = 12W, then Ea = Pda / Ia = 12 / 0.046 = +259Vdc."

Patrick, you are losing me in this calculation. I'm fine until you discuss
"peak swing 0.044A" Where is that from?
So far I got to Vrms = 155, Vpeak = 204, but don't follow the Ia peak swing.
I see .046A = .044 * 1.05.
Also, is that a typo, "Let Ia be 5%...... = 0.46A", did you mean 0.046A?

I'm trying to replicate the calculation for a 1W 12AU7 amp, assume
RL=7700...if I could follow it, I could figure it! I'm sure it's obvious to
you, but not to me!

Thanks.
Phil

[Patrick Turner]

On Nov 4, 1:41*am, "Phil_S" wrote:
"Patrick Turner" *wrote in message

...
snipped it all for brevity, content was fabulous

Patrick:
I didn't want to be presumptive. *A friend said you hang out here. *I
couldn't find your web pages.

My web site was down since last Friday until yesterday. Unfortunately,
Melbourne IT who are licensed to register domain names sent my renewal
notice invoice to the wrong email address and my rego ran out so they
pulled the switch.
I paid them last Monday and last night my site re-appeared and also re-
allowed my email related to my website.
perhaps my site may take time to re-appear at servers around the
globe.

Be patient, all will be OK in the fullness of time.

*Unfortunately, there is another Patrick
Turner who plays US Pro Football. *Searching turned up nothing. *Thank you
for your thoughtful reply and for the link to your pages.

There are quite a few ppl with my name. Maybe there is not anything
really unfortunate about this IMHO.

I played football at school in the 1950s/60s. We played what we call
Rugby Union, and it is a British origin form of football which leaves
you battered and bruised every time it is played. I was a "second
rower". I have never liked "footy" very much and I was much happier
riding a bicycle.


I appreciate your comments about not trusting inexperienced instinct;
impulsiveness is even worse. *You don't know the half of it. *This was one
of those days when I was just looking for an excuse to do something like
this. *I've been dabbling in building guitar amplifiers for a number of
years. *I've done about a dozen. *Only the first one was from a kit, so I've
got reasonable amateur level experience. *I still have much to learn. *I'm a
curious person. *As I said, I figured this was a cheap OT and it was an
opportunity to see what makes it tick. *This is about fun with transformers.
I didn't imagine I'd get from this "project" a high quality OT. *Even so,
for a guitar amp, I believe quality is a bit less of an issue. *I don't need
20Hz at the low end or 20KHz at the top end.

OK. But guitar amps benefit from having rugged OPts and larger than
required, or larger than what some damn accountant allowed to be
fitted to a radio in 1955.

As for the meter, I was really quite surprised to see that I'd toasted it..
It is a Triplett 9045, which is OK for a hobby meter and has stood by me
well for several years. *I've got two more hand held meters and I just put
the old Fluke 8600A bench meter up for a battery charge. *I'm sorry to see
that Triplett go. *It seems to be working on everything but the Ohms.
shrug

Maybe your meter is fixable. But even a simple old multimeter circuit
can be difficult and confusing to analyse.

I once totally fried nearly all solid state devices in a 20MHz Dual
trace oscilloscope by using a 1: 30 step up transformer to examine
really low voltage signals. All went well until I accidently touched
the low voltage input winding onto +70Vdc.
This sent a momentary pulse of +2000V into the input, and solid state
really hates that. I spent $200 to fix it. I got most functions back,
but not quite all and it was never the same again. I learnt to be more
careful, and to use cheap oscilloscopes.



Thanks also for some calculations, confirmations and corrections. *This,
with your SE pages on the web should keep me busy for a while. *I'm feeling
much better about being pointed in the right direction. *I am hoping for the
simple satisfaction of making something that works. *How well it works can
be a surprise. *Some of the measurements will be difficult to make with a
limited amount of test equipment. *I think you've given me the excuse I need
to get the digital caliper. *This is an inexpensive tool and who doesn't
need another tool?

An oscilloscope would be a great boon to your toolset. Any old CRO is
better than none, something analog, single trace and only 1MHz of bw
will do fine, and maybew you find something pre-used which is a
bargain.
Or else set up an old PC and sound card, but sound cards just don't
like accidental high voltage inputs when measuring tube amp voltages
well over +/- 50 peak volts. So you'd need to make a circuit to limit
the voltage levels and protect the PC which means yet another lot of
learnt skills.


I can easily get a new tranny. *That, as you've gathered, isn't the point.

[Patrick Turner]

On Nov 4, 5:12*am, "Phil_S" wrote:
OK, I've got some "findings" that suggest I can't get from here to there.

1) For 6V6 at 4.8W, I really should be using 32 AWG. *Further work suggests
the best case it that the existing primary wind is 37 AWG and more likely 38
AWG. *This is too thin. *The core area is small that calculations suggest is
needed.
2) The primary resistance for 3363 estimate turns is 643 ohms. *Patrick says
it should be less than 375 ohms. *This would probably be true for 32 AWG, I
estimate I'll need about 1000 ft, and that is 168 ohms (table value).
3) The remaining margin on the bobbin is about 3mm. *If I did the calc
right, I've got room for about 90 turns of #20; I need 95 for a 4z winding.

Maybe I'm not "getting it" completely here. *Maybe I've flubbed a few of the
numbers. *Even so, the whole thing seems too small. *I think maybe I've got
a 1-2W OT.

OK first of all, if the primary winding resistance, RwP = 5% of the
primary RL and the RwS was 5% of the secondary Rw, then total winding
losses are 10%, and this is a good figure for a fairly good quality SE
OPT.
But in fact many small radio OPTs meant for 6V6 or similar tubes the
total losses are up to 25%, and hence Rw of either P or S windings can
exceed 10% of the corresponding load values.

Many old OPT had primary wire size which was barely able to take the
idle current of say 50mA in many apps.
if a tube went into saturation from bias failure then Ia might rise to
150mA and the heat in a winding of say 600 ohms = 13.5W and the OPT
dies from a fused winding or shorted turns.

Many old radios were designed so only 3 watts could ever come from the
anode circuit. But where the the winding losses were say 25%, then
0.75W would be lost in the OPT and you'd get only 2.25W from the
secondary, but quite enough for a radio on the mantle peice to tell
you the football score.


Maybe I can rewind this for half a 12AU7 -- maybe I can make a one tube amp?
Maybe a 12AU7 pre with a 6C4 output? *I guess I'm hell bent on finding a use
for this piece of junk. Remember, fun with tubes and transformers -- the
process is as important as the product.

I'm looking to change the plan here. *I think it is not going to work for a
6V6 or a 6AQ5.

Flipper, you asked about the wire chart. *It's here at the end of this
article.http://www.deerloverssite.org/TRANSFORMERS.html

Patrick Turner wrote the following:
"If you wanted RL = 5k, then you can figure out exactly what Ea and Ia you
can have.
Using an OPT with 10% winding losses, expect anode efficiency = 40%.
So if Pda = 12W, then expect 4.8W max.
PO = Va squared / RL.
4.8 = Va squared / 5,000,
So Va = 155Vrms = 219V peak which gives Ia peak swing 0.044 A.
Let Ia be 5% more than peak Ia swing = 0.46A.
If Pda = 12W, then Ea = Pda / Ia = 12 / 0.046 = +259Vdc."

Patrick, you are losing me in this calculation. *I'm fine until you discuss
"peak swing 0.044A" *Where is that from?
So far I got to Vrms = 155, Vpeak = 204, but don't follow the Ia peak swing.
I see .046A = .044 * 1.05.
Also, is that a typo, "Let Ia be 5%...... = 0.46A", did you mean 0.046A?

Peak Current load swing = peak V swing / RL = 219 / 5,000 = 0.0438
Amps peak.

In any SE amp the idle Iadc should be about = peak load I swing plus
10%, or about 48mA in this example.


I'm trying to replicate the calculation for a 1W 12AU7 amp, assume
RL=7700...if I could follow it, I could figure it! *I'm sure it's obvious to
you, but not to me!

RL for a single triode section of 12AU7 would be about 16,000 ohms.

With both triodes in parallel, say 8,000 ohms.

OK, you want 1W?

The Va rms = sq.rt ( PO x RL ) = sq.rt ( 1 x 8,000 ) = 89Vrms.

Ia rms = 89 / 8,000 = 11.1mA, so peak Ia = 1.414 x 11.1 mA rms =
15.8mA.

The Ea and Ia and the rest you can work out maybe.....

Patrick Turner.

Thanks.
Phil

[Phil_S]

"Patrick Turner" wrote in message
...

------------------
The Ea and Ia and the rest you can work out maybe.....

Patrick Turner.

---------------------

Yes, Patrick, I think I can! Also, I realized after posting that 7.7K is
wrong, as your typical 1W 12AU7 guitar amp is often built with a Fender
reverb transformer as the OT. I believe this item has 22.5K on the primary.
Using 16K as the assumed primary on that POS OT I'm trying to save, it looks
like I only need 107 turns for the secondary and that's good news!

Thanks again for your help.

Phil

[Patrick Turner]

On Nov 5, 12:52*am, "Phil_S" wrote:
"Patrick Turner" *wrote in message

...

------------------

The Ea and Ia and the rest you can work out maybe.....

Patrick Turner.

---------------------

Yes, Patrick, I think I can! *Also, I realized after posting that 7.7K is
wrong, as your typical 1W 12AU7 guitar amp is often built with a Fender
reverb transformer as the OT. *I believe this item has 22.5K on the primary.
Using 16K as the assumed primary on that POS OT I'm trying to save, it looks
like I only need 107 turns for the secondary and that's good news!

Thanks again for your help.

Phil

I recall Fender commonly uses a 12AT7 paralleled as the driver amp
into the reverb tranny to excite the springs.
Not much power is needed. But Fender made a stand alone reverb unit
with its own PSU with 5Y3, 6V6, 12AX7 and spring unit in a box. Maybe
that's the best reverb unit ever made. But I once installed a reverb
unit in a big 100W Marshal head and I used a paralleled 12AT7 into a
5k:4,8,16 trannny meant as a 100V line tranny for powering ceiling
speakers.
The real low bass performance was not critical. The load the 12AT7 is
setable depending on the sec taps, so if you have a tank coil load of
8 ohms and that connects to to a 4 ohm tap, the primary load becomes
10k and not 5k, so then the Vswing is wider and you get less THD and
more power. 12AU7 or 6SN7 or 12BH7 are als good. The small "5W" rated
OPT was available as a line tranny from an electronics store. The
tranny was ungapped, but because Iadc was only about 8mAdc, the core
did not saturate fully so it worked very well.
I said to the guy for whom I worked that the range of reverb went from
nothing, to slightlly warm, then to molten chocolate, then to being
like tunnel a mile long. He said I was wrong about the chocolate -
" ....I reckon its like nice hot wet cow****".

OK. I wasn't to argue. He was very happy. But my circuit was based on
the Fender design and worked really well. I had to make sure the
spring unit was placed as far away from the mains tranny or else they
pick up a lotta hum.

A little dasha reverb goes a long way....

Patrick Turner.

[Patrick Turner]

On Nov 7, 3:21*pm, flipper wrote:
On Sat, 6 Nov 2010 19:41:11 -0700 (PDT), Patrick Turner







wrote:
Others concluded...........

snip

I'm strange. I can't understand why anyone wants the weird responses
some tone stacks give.

For starters, the pickup response isn't flat.

But then I think a bit like anyone technical, and I have a mind full
of mental pictures about tone controls and if adjust a knob labelled
'treble', then ONLY above 1kHz will be adusted up or down in level,
leaving everything else fixed. Ditto for bass.

Might be fine if the source is flat but a guitar pickup isn't.

I've never measured the response of a geetah pick up

Btw, why are you 'screwing up' a nice flat source anyway?

Well why would anyone?

But the sound is dull and boring if the response is flat.

Guitar players do like to boost the treble to hell and brighten the
sound, and to the extent that the upper HF harmonics are what cause
the amp to overload giving "intersteing sounding" IMD products which
are different to where LF F are allowed to be so high in amplitude
they modulate the HF. But hey, a bit of either will do as long as
whatever can be done to alter the sound and uniquify the sound can be
done, at least temporarily. Well, there is only so much that can be
done with tone controls as we know them without using say 3 tone
stacks cascaded, or using some form of digitally generated artifacts
and sampling and processing that so many have become reliant upon to
try to get more uniqueness than the next guitarist along.


And varying volume
should have no effect on tone control settings.

So much for the ear's frequency response shift at low volumes, eh?

I also like musicians to rely on their creativity rather than tone
controls or brand of amps to entertain me,

The musician has no control over the magnetic pickup characteristics
(other than picking one).

Probably not. But there's more than one pick up. One might be forgiven
for thinking a graphic eq unit would do more for most musos but their
range of F is wide, so bass, mid and treble is all that can be used,
lest some wanted F become almost silent and some unwanted F become
prominent.

The whole business of the electric guitar sound is based around the
basically pleasant sound of a plucked string resonating a peice of
thin wood of a box with a hole in it. But rock music artists want a
lot more excitement than an amlified acoustic guitar; they want the
sound of POWER and want their sound to generate awe in the listeners,
a sence of urgency, and stress, and the opposite of relaxation, they
want conveyed passion, a wild ride. For that you just basically need
square waves fed to a speaker, and an over driven tube amp operating
in class C during sustained tones does the job best.
This passion recipe is carried too far in most "Metal" players, and is
mightily boring to most ppl over 30 because it invokes a memory of
aimless energy at a time when most have learnt to aim their energy,
and they wish to understand lyrics which they wish to be meaningful
and without sub-titles, and they want less repititious noise and more
line to line diversity.
So hence there is actually a wide variety of use for guitar amps
between being flat and distortion free and being radically overdriven.



Just exactly what is the 'pure, natural, uncorrupted sound' of a
vibrating string made of what tensioned over what? Hint: There isn't
one.

You have asked an exactly good question.

A Stradivarius is claimed to sound better than a cheap Chinese knock
off, or any other violin for that matter. Why? They're 'technically'
the same thing: just strings over wood, and even shaped the same.

Well, the Stradi just sounds better to the many people who like the
music written for violin by masters such as Bach, Beethoven, Motzart
et all.

The balance of harmonic levels achieved produced by resonant wooden
boxes and strings as put together 200 years ago by italian masters is
necta to the ears; like the finest of wine to the palete, like the
most moving art or sculture is to the eye.

Maybe one day the Chinese produce better violins than the old Italian
masters. Don't hold your breath. I've heard some good electrified
vilolins but its rare. So it is with electrified harps and cellos and
with added digital effects.

The music of the masters of 200 years ago has lasted. It has not been
dropped and forgotten. It has of course been used as a basic source
for inspiration and composition for works by bands such as the Beatles
and where electric guitars were at the forefront.

The harpsicord was the popular instrument equivalent of the modern
electrified guitar around which many gathered to sing together as a
joie de vie passage of life. Just because ppl didn't have amps in 1750
didn't mean they didn't have a pop music experience. Well, certainly
that was the scene of the rich who could afford such sociality and the
instruments and time to learn how to play them. Today's peoples of any
class can while away time spent making music, at least after their
work is done, and youthful energy permitting.


I suggest it's because of the 'tone' caused by the selected bits that
went into it's making..

well yeah. Lotsa thought, and trial and error.

An electric guitar is relatively useless without the amplifier,
meaning the amplifier *is* 'part of the instrument' and selecting
'amplifier sound' is just as much a part of the total instrument
called an 'electric guitar' as deciding whether to make a string banjo
or violin, including what wood to use and a host of other 'tone
shaping' factors. There, too, the 'body' is a 'tone altering
amplifier'.

In short, the notion you're apparently operating under, that there is
some sort of original 'real' source you simply want to 'accurately'
amplify, does not apply.

My notion is that there is only so much that can be done to change
tone with the tone stacks currently available.

My technical brain asseses what the controls are doing, or should be
doing, while perhaps a muso just guesses.

But if any muso is happy with X, Y and Z setting of the knobs, then
that's all that matters.

Interesting that you're miffed at tone stacks but apparently think
(from your other post) mangling the 'original source' with a reverb is
perfectly fine.

Well, I feel some tone stacks are just confusing in operation because
of the un-predictable outcome of making an adjustment.

But reverb is an entirely different matter and involves adding a
variable amount of echoes and reverberations to an otherwise boring
dry sound. Reverb is like a good sauce on a nice plate of vegetables,
or like a slightly revealing dress on a beautiful lady singer.

But in this post de-constructionalist age anything goes about artistic
definitions.

But beauty still remains in the ear of the listener........

For every 1,000 musicians, maybe only one will shine above the others,
and he/she might do it all without much reliance on their gear, any
old amp might do if they have talent.



rather in the same way I
expect story lines and character devellopment in movies to be 3
dimensional, or even more dimensional, but clearly told, and
preferably without reliance on explosions and special effects.

There's no doubt some go overboard with special effect' (effectively
being 'the movie') but, hate to burst your bubble, there are
explosions and such during a war so, as but one example, if that's
your 'story' then simply having '3 dimensional characters' isn't going
to cut it.

Only a very small percentage of daily possible human drama worth
putting up on the silver screen involves continuous huge explosions.
Shakespeare showed what was possible in the old days.....

But now we have "effects" industries, and anything from Hollywood must
be action packed and it mostly bores me ****less to sit through
implausible crap produced by a huge team of ppl who just must be used
because they exist.
Sound in movies is often horrid, with key speach lines spoken by
whisperers into a cupboard while noise and music rage in the
background/foreground and the plot is routinely made inperceptible by
anyone over 30 who does not have the most tenacious hearing
capabilities. In other words, the "more" they put into media
entertainments becomes less in effect.
I once heard Mick Jagger playing a plain guitar and a plain old amp
and doing some some Missisippi blues numbers and I thought he really
understood the genre. he "had it". Just as good as the old black guys
from years ago. No need for much knob twiddling at all - it was a
case of less is "more". Mick's 'Roots" album wan't bad. Taj Mahal and
Rye Cooder also relied on sheer talent and musicality, and not on the
tone settings.





Anyway, I would have thought the Ampeg type of tone controls with
bass, mid, treble were way ahead of the rest.

Some like it and some think it muddy, or have other complaints.

There are few musos who would ever agree on anything.

They are artists. Consistent opinions are never to be had with
artists.


But then the basic tone
stack which is used in 90% of guitar amps is the product of a mind
which asks "how can tone be changed at a minimum cost?"

I will never understand why you insist on manufacturing fantasies
about things you have no knowledge of.

It matters not that you may not understand me. But I repair/modify
guitar amps regularly for people and generally get very well received
appraisals for my efforts and I get repeat orders. How could I not
have in-depth knowledge of guitar amp technology?

I put my guitar amp hat on with guitar amp work and my hi-fi hat on
for hi-fi amps.

The two forms of amps have much in common but also differ in many
ways.



I would never dream of claiming what "90%" of guitar amplifiers have,
or pretend to read minds, but the typical Fender and Marshall have a
three knob tone stack, as does my own "Travis Tone." Not surprising
since I modeled it from the Marshall tone stack.

Well, there is such a thing as the typical tone stack as used in most
amps such as Fender and Marshall and a whole pile of others. I have
the Groove Tube book with 50+ schematics of many brands and maybe 90%
have similar tone stacks.


without too
much regard for the musicians who might struggle for hours twiddling
knobs to get a setting they like, and then as soon as they decide to
play at a lower level, they have twiddle more knobs after adjusting
levels. Anyway every musician thinks he or she is unique of course and
they all have preferences, and they seem to put up with what the
accountants worked out for them many years ago.

If there is a hell yours would undoubtedly be to spend eternity in a
room full of accountants perpetually chanting "we do not do design, we
do not do design, we do not do design."

Well, accountants design unintentionally ( or intentionally ) because
they have to say no to the engineers and marketting ppl or anyone else
who wants to invest more detail, weight, quality, whatever into a
given product.

Somebody has to tell the team there is a limited budget to cover
production costs and to make a profit for share holders and to afford
the wages of the CEO and his Caddilac. Companies go broke without
accountants, or bean counters telling half the team, "NO!!!" on a
daily basis.


The Ampeg tone controls are much more expensive than the cheap way
used by so many other brands.

Too bad it sounds muddy.

But "muddy" is an artistically subjective thing, and its nature is
debatable.

Patrick Turner.

[Patrick Turner]

On Nov 8, 7:21*pm, flipper wrote:
On Sun, 7 Nov 2010 02:02:41 -0800 (PST), Patrick Turner
snip,

I've never measured the response of a geetah pick up

Rather an important oversight if one is going to talk about guitar
amplifier tone shaping..

But pickups vary, so there is hardly any reason to measure the
response and build the amp around the PU.
What happens when a different guitar is used? Methinks one size fits
all with simple bass/mid/treble adjust should allow enough tone
shaping, short of using graphic eq.

Btw, why are you 'screwing up' a nice flat source anyway?

Well why would anyone?

But the sound is dull and boring if the response is flat.

Not when the goal is accurate reproduction of the 'original'.

Few musos ever want a purely flat and non distorting amp. They usually
want the music warmed with a dash of reverb and some boost to HF -
brightness.

And the question after a recording session? "What can you guys do to
make it sound better?". The engineers realise the muso isn't always
happy with the sound of himself singing /playing, and is desperate get
the techs to trick it all up with processing so CD sales might be more
than 2 pcs.

I've heard the guys from recording studios tell me what goes on and
just how demanding the majority of talentless wannabes are.


Guitar players do like to boost the treble to hell and brighten the
sound, and to the extent that the upper HF harmonics are what cause
the amp to overload giving "intersteing sounding" IMD products which
are different to where LF F are allowed to be so high in amplitude
they modulate the HF. But hey, a bit of either will do as long as
whatever can be done to alter the sound and uniquify the sound can be
done, at least temporarily. Well, there is only so much that can be
done with tone controls as we know them without using say 3 tone
stacks cascaded, or using some form of digitally generated artifacts
and sampling and processing that so many have become reliant upon to
try to get more uniqueness than the next guitarist along.

And varying volume
should have no effect on tone control settings.

So much for the ear's frequency response shift at low volumes, eh?

I also like musicians to rely on their creativity rather than tone
controls or brand of amps to entertain me,

The musician has no control over the magnetic pickup characteristics
(other than picking one).

Probably not. But there's more than one pick up.

Because the 'tone' is not only dependant on the pickup but it's
location.

As I said, the electronics is 'part of the instrument'.

Well indeed.

One might be forgiven
for thinking a graphic eq unit would do more for most musos but their
range of F is wide, so bass, mid and treble is all that can be used,
lest some wanted F become almost silent and some unwanted F become
prominent.

The whole business of the electric guitar sound is based around the
basically pleasant sound of a plucked string resonating a peice of
thin wood of a box with a hole in it.

An electric guitar is not a "plucked string resonating a piece of
thin wood of a box with a hole in it." That's an acoustic guitar, or a
violin, or a banjo (except the body isn't all wood) or a viola, or any
number of string instruments, all of which sound different because the
'mechanical amplifier' creates a different 'tone stack'.

Jazz guitars with a pair of F holes are hollow-bodied resonant gizmos.
Pick ups are used to pick up whatever is the result.

Most rock guitars ate solid, so no few additional resonant tone
artifacts are generated beyond the many harmonics in the strings.


But rock music artists want a
lot more excitement than an amlified acoustic guitar; they want the
sound of POWER and want their sound to generate awe in the listeners,
a sence of urgency, and stress, and the opposite of relaxation, they
want conveyed passion, a wild ride. For that you just basically need
square waves fed to a speaker, and an over driven tube amp operating
in class C during sustained tones does the job best.
This passion recipe is carried too far in most "Metal" players, and is
mightily boring to most ppl over 30 because it invokes a memory of
aimless energy at a time when most have learnt to aim their energy,
and they wish to understand lyrics which they wish to be meaningful
and without sub-titles, and they want less repititious noise and more
line to line diversity.
So hence there is actually a wide variety of use for guitar amps
between being flat and distortion free and being radically overdriven.

You trying to reduce the electric guitar to whatever music you don't
happen to like is irrelevant.

I like some, and don't like some. I have my reasons. Much rock music
is just noise, kids just jerking off and spraying us all with sound
that is irksome, sickening, boring, boorish, peurile, etc etc etc.
Having said that, a lot of classic old music played on old instruments
is all just noise in vain, cluttering our ears and brains with aural
junk.

I make no apologies for being at ease with the idea that some art is
utter crap, and some has something which can be appreciated.


Just exactly what is the 'pure, natural, uncorrupted sound' of a
vibrating string made of what tensioned over what? Hint: There isn't
one.

You have asked an exactly good question.

A Stradivarius is claimed to sound better than a cheap Chinese knock
off, or any other violin for that matter. Why? They're 'technically'
the same thing: just strings over wood, and even shaped the same.

Well, the Stradi just sounds better to the many people who like the
music written for violin by masters such as Bach, Beethoven, Motzart
et all.

Not so.

Well, one major expense involved with becoming a serious classic music
musician when one has learnt enough at a music school to stop the
audience walking out is the cost of buying a decent instrument. I've
seen the young ppl at our local Canberra School Of Music and seen
their purchases. Often the entry cost for a "good enough" instrument
is 20 grand.

Perhaps these folk might disagree with you.

The balance of harmonic levels achieved produced by resonant wooden
boxes and strings as put together 200 years ago by italian masters is
necta to the ears; like the finest of wine to the palete, like the
most moving art or sculture is to the eye.

If that made any sense then any "resonant wooden
boxes and strings as put together 200 years ago by Italian masters"
would have the same reputation, but they don't

Amoung all things, some things are judged better than others.

The music industry afficionardos and cognescenti and glitterati all
make the most bitchy touchy egotistical judgements about all things
involved in their interest. Not all players singers are the same. The
criticisms of everything are merciless....



Maybe one day the Chinese produce better violins than the old Italian
masters. Don't hold your breath. I've heard some good electrified
vilolins but its rare. So it is with electrified harps and cellos and
with added digital effects.

The music of the masters of 200 years ago has lasted. It has not been
dropped and forgotten. It has of course been used as a basic source
for inspiration and composition for works by bands such as the Beatles
and where electric guitars were at the forefront.

The harpsicord was the popular instrument equivalent of the modern
electrified guitar *around which many gathered to sing together as a
joie de vie passage of life. Just because ppl didn't have amps in 1750
didn't mean they didn't have a pop music experience. Well, certainly
that was the scene of the rich who could afford such sociality and the
instruments and time to learn how to play them. Today's peoples of any
class can while away time spent making music, at least after their
work is done, and youthful energy permitting.

Lord only knows that dance through the tulip garden has to do with it.

I suggest it's because of the 'tone' caused by the selected bits that
went into it's making..

well yeah. Lotsa thought, and trial and error.

The point was that all the 'bits' of an instrument contribute to the
'tone' and if you had waited for the next sentence you'd have seen it
explain that the amplifier is one of the 'bits' to an "electric"
guitar.

I agree entirely about the amp being part of the instrument.

An electric guitar is relatively useless without the amplifier,
meaning the amplifier *is* 'part of the instrument' and selecting
'amplifier sound' is just as much a part of the total instrument
called an 'electric guitar' as deciding whether to make a string banjo
or violin, including what wood to use and a host of other 'tone
shaping' factors. There, too, the 'body' is a 'tone altering
amplifier'.

In short, the notion you're apparently operating under, that there is
some sort of original 'real' source you simply want to 'accurately'
amplify, does not apply.

My notion is that there is only so much that can be done to change
tone with the tone stacks currently available.

Maybe that "so much" is the intended "so much."

My technical brain asseses what the controls are doing, or should be
doing, while perhaps a muso just guesses.

I'm suggesting that a 'technical assessment' without 'assessing' the
pickup, or any of the other 'tone' elements, and what the 'muso'
desires the instrument to sound like is neither technical nor musical.

Well, when ya buy a standard Fender/Marshal/Whatever amp, you buy what
the makers intended, a generic one size fits all with no customized
match between amp and pickups.

The amp is a result of techicallity, not any sense of musicality in
the designers. The muso amp using tubes is **inherently musical** and
there is almost nothing anyone can do to add musicality. Perhaps users
may "add musicality" by means of plugging in effects boxes. The trend
has been ever more complex front panels with ever more knobs and
buttons to press and fewer vacuum tubes and many more opamps. More
technical, less musical.



But if any muso is happy with X, Y and Z setting of the knobs, then
that's all that matters.

I'd say someone must be or else the knobs would be different (as,
indeed, they are with some preferring the 'sound' of a Marshal or a
Fender or whatever amp produces the preferred 'tone'.)

Interesting that you're miffed at tone stacks but apparently think
(from your other post) mangling the 'original source' with a reverb is
perfectly fine.

Well, I feel some tone stacks are just confusing in operation because
of the un-predictable outcome of making an adjustment.

Just because you can't predict it doesn't mean no one can.

A lot is doable by trial and error. Suck it and see.

Ppl cope.

For heaven's sake, it's an electronic circuit. Turn the knob to 10
o'clock and it's going to do the same thing every time.

Yes, but the response in many muso amps varies depending on settings
of bass/treble settings.

It may not matter much.

But reverb is an entirely different matter and involves adding a
variable amount of echoes and reverberations to an otherwise boring
dry sound. Reverb is like a good sauce on a nice plate of vegetables,
or like a slightly revealing dress on a beautiful lady singer.

I'm tickled to death you like reverb but I've heard plenty of 'non
boring sound' without it.

So have I. Especially when the local Canberra Orchestra plays a
concert without any amps, reverb, and in a good hall.

But in this post de-constructionalist age anything goes about artistic
definitions.

But beauty still remains in the ear of the listener........

For every 1,000 musicians, maybe only one will shine above the others,
and he/she might do it all without much reliance on their gear, any
old amp might do if they have talent.

If they have talent the first thing they'll do is get equipment to
match.

But talent may overcome the limitations of the instrument. A good
craftsman does not blame his tools; he produces excellent results with
a minimum of tools.

But I agree, most successful musicians spend a good part of their
earnings on good enough instruments they can afford.

With some musos it matters not what they buy; they just don't have
much talent.


rather in the same way I
expect story lines and character devellopment in movies to be 3
dimensional, or even more dimensional, but clearly told, and
preferably without reliance on explosions and special effects.

There's no doubt some go overboard with special effect' (effectively
being 'the movie') but, hate to burst your bubble, there are
explosions and such during a war so, as but one example, if that's
your 'story' then simply having '3 dimensional characters' isn't going
to cut it.

Only a very small percentage of daily

Who said anything about 'daily'?

Depends.....

Patrick Turner.

[YD]

Late at night, by candle light, Patrick Turner
penned this immortal opus:


I'e got several old PCs laying around, all still working. I would like
to have ONE fitted with a spectral analysis prgram and sound card
installed. I do get by on old analog gear but spectral analysis would
tell me a whole lot more.



I use Visual Analyzer for audio work, downloaded from
http://www.sillanumsoft.org/. It's pretty complete, several waveforms,
independent adjustments for each channel. Measures frequency,
amplitude, FFT, transfer function, and a lot more dependent mostly on
your imagination. It does need some twiddling until you get the hang
of it, but so does most anything and it didn't take me all that long.
On top of all that, it's freeware.

I do recommend some protection circuitry, the simplest being a
resistor and a couple of inverse-parallel diodes. Since the sound card
input impedance is on the lowish side an opamp buffer would be better.

- YD.
--
Remove HAT if replying by mail.

[Patrick Turner]

On Nov 10, 4:14*pm, YD wrote:
Late at night, by candle light, Patrick Turner
penned this immortal opus:



I'e got several old PCs laying around, all still working. I would like
to have ONE fitted with a spectral analysis prgram and sound card
installed. I do get by on old analog gear but spectral analysis would
tell me a whole lot more.

I use Visual Analyzer for audio work, downloaded fromhttp://www.sillanumsoft.org/. It's pretty complete, several waveforms,
independent adjustments for each channel. Measures frequency,
amplitude, FFT, transfer function, and a lot more dependent mostly on
your imagination. It does need some twiddling until you get the hang
of it, but so does most anything and it didn't take me all that long.
On top of all that, it's freeware.

I do recommend some protection circuitry, the simplest being a
resistor and a couple of inverse-parallel diodes. Since the sound card
input impedance is on the lowish side an opamp buffer would be better.

Maybe a cathode follower buffer with following R plus diode clamp
would be better when working around vacuum tube circuits where one
accidental touch of a probe onto +500Vdc could blow the opamp and the
sound card and PC right out of its case.

Thanks for the link; it appeared to download OK.

Patrick Turner.



- YD.
--
Remove HAT if replying by mail.

[YD]

Late at night, by candle light, Patrick Turner
penned this immortal opus:

On Nov 10, 4:14*pm, YD wrote:
Late at night, by candle light, Patrick Turner
penned this immortal opus:



I'e got several old PCs laying around, all still working. I would like
to have ONE fitted with a spectral analysis prgram and sound card
installed. I do get by on old analog gear but spectral analysis would
tell me a whole lot more.

I use Visual Analyzer for audio work, downloaded fromhttp://www.sillanumsoft.org/. It's pretty complete, several waveforms,
independent adjustments for each channel. Measures frequency,
amplitude, FFT, transfer function, and a lot more dependent mostly on
your imagination. It does need some twiddling until you get the hang
of it, but so does most anything and it didn't take me all that long.
On top of all that, it's freeware.

I do recommend some protection circuitry, the simplest being a
resistor and a couple of inverse-parallel diodes. Since the sound card
input impedance is on the lowish side an opamp buffer would be better.

Maybe a cathode follower buffer with following R plus diode clamp
would be better when working around vacuum tube circuits where one
accidental touch of a probe onto +500Vdc could blow the opamp and the
sound card and PC right out of its case.

Thanks for the link; it appeared to download OK.


Hell yeah, whatever works. Talk about mixed technology. The sound card
only takes 1Vp-p or something like that so you'll need an input
attenuator too. Rip one from a scope schematic and you're set.

- YD.
--
Remove HAT if replying by mail.

[Big Bad Bob]

On 11/10/10 00:07, Patrick Turner so witilly quipped:
I do recommend some protection circuitry, the simplest being a
resistor and a couple of inverse-parallel diodes. Since the sound card
input impedance is on the lowish side an opamp buffer would be better.

Maybe a cathode follower buffer with following R plus diode clamp
would be better when working around vacuum tube circuits where one
accidental touch of a probe onto +500Vdc could blow the opamp and the
sound card and PC right out of its case.

Assuming an 11 meg input Z (switched attenuator?), a series 1 megohm 1/2
W resistor going into a high impedence op-amp with external opposing
zeners or reliable internal protection circuitry should work as well.
Configured as a voltage follower it should prevent any impedence
problems and allow you to use a standard 1x/10x O-scope probe. That'd
make a simple breadboard test as well.

Heh, this makes me think - I haven't owned a scope for a while, and I
have a lot of PCs laying about. I should experiment with an
microcontroller chip and see if I can use it for this purpose.

[Patrick Turner]

On Nov 11, 8:26*pm, Big Bad Bob BigBadBob-at-mrp3-
wrote:
On 11/10/10 00:07, Patrick Turner so witilly quipped:

I do recommend some protection circuitry, the simplest being a
resistor and a couple of inverse-parallel diodes. Since the sound card
input impedance is on the lowish side an opamp buffer would be better.

Maybe a cathode follower buffer with following R plus diode clamp
would be better when working around vacuum tube circuits where one
accidental touch of a probe onto +500Vdc could blow the opamp and the
sound card and PC right out of its case.

Assuming an 11 meg input Z (switched attenuator?), a series 1 megohm 1/2
W resistor going into a high impedence op-amp with external opposing
zeners or reliable internal protection circuitry should work as well.
Configured as a voltage follower it should prevent any impedence
problems and allow you to use a standard 1x/10x O-scope probe. *That'd
make a simple breadboard test as well.

Heh, this makes me think - I haven't owned a scope for a while, and I
have a lot of PCs laying about. *I should experiment with an
microcontroller chip and see if I can use it for this purpose.

The bother with any buffer between amp-under-test is that the buffer
adds its distortion. However, usually a typical 6CG7 CF has very low
THD if its output voltage is limited to 1Vrms which should be enough
to drive a sound card without frying it, and to allow analysis.
If the test signal is hundreds of volts at a tube anode, it can be
usually reduced with a resistance divider say 1M : 10k0, giving a
100:1 voltage step down ratio. The 10k can be a 10k pot or switched
attenuator and the 1M made up with a few series R to limit the the
possibility of excess voltage appearing across resistors, even though
Pd is well within the rating.

If one has 300Vrms at an anode at +500Vdc, one might also use a 0.22uF
x 2,000V rated cap to drive the R divider1,000V.

There may be no need for a buffer in this case because the 10k or less
offers a low enough source R to drive a sound card.

Before I set up a PC to do that spectral analysis stuff, there is much
else to be explored and maybe implemented. I am presently playing
around with a Gilbert Cell to try to make a better AM sig gene, and
for understanding something that should be OK for FM stereo decoding
without the old fashioned way using coils and a ring diode de-
modulator.
The Gilbert Cell has many uses and appears in a lot of electronics,
and often without anyone realising just what is there. Apparently, one
may be made using 6 triodes, so say 3 x 6DJ8 would do, and not be very
complex.

But I have digressed away from SE OPT stuff......

Analog electronics was just about all invented before 1970; but how it
is implemented continues slightly evolve, or else modern ppl find new
ways of using tubes to do what has been done in ICs. Nobody in 1966
might have thought to make a Gilbert cell with 6 triodes but that
don't mean one should not give it a try on the grounds that it isd a
fascinating puzzle at least.


Patrick Turner.

[Big Bad Bob]

On 11/11/10 06:08, Patrick Turner so witilly quipped:
I am presently playing around with a Gilbert Cell

heh - you made me google what it is - balanced modulator. Got it. Now
you can avoid tuning coils and use crystal filters instead.