[Raymond Koonce]

Hi RATs,

I had the good fortune to attend the European Triode Festival in
Biezenmortel Netherlands a few days ago. It was a cool fest with about
80 participants. I made a web page of photos I shot there. Take a look
at http://www.timebanditaudio.com/etf2007/etf2007.html

Raymond

[Patrick Turner]

Raymond Koonce wrote:

Hi RATs,

I had the good fortune to attend the European Triode Festival in
Biezenmortel Netherlands a few days ago. It was a cool fest with about
80 participants. I made a web page of photos I shot there. Take a look
at http://www.timebanditaudio.com/etf2007/etf2007.html

Raymond

Some nice work done by diyers there but a lot is very poorly made
breadboard stuff. But they gotta start somewhere.

Lots of 845s in there.

I am proceeding seriously with constructing a
pair of monoblock 845 amps with two in parallel per channel.

So far I have power and OPTs both with 72mm stacks of 51mm tongue GOSS
lams,
and 5 chokes per channel, two 4H B+ chokes, one 60H choke for
dc supply to 3 paralleled EL84 SET drivers, and two 20mH chokes for the
pair of choke input
supply for 10Vdc x 3.3Adc heaters to 845.

I have so far 14 x 470uF x 400v rated caps.

I thought the chassis was big enough when I began but I wish it was 25
mm in each dimension....

Choke details as follows,

4H+ at 200mA,
32S x 25T, GOSS E&I.
1,400t x 0.4mm dia Cu, 30 ohms dcr.
gap = 0.18mm right across the core.( actual gap = 0.36mm )

4H+ at 200mA, but only 160mA used,
25S x 25T, GOSS E&I.
1.750t x 0.35mm Cu dia, 42 ohms dcr.
gap = 0.27mm right across core, ( actual gap = 0.54mm )

60H at 40mA,
32S x 25T GOSS E&I.
5,200t x 0.2mm Cu dia, 440 ohms dcr.
gap = 0.27mm right across core, ( actual gap = 0.54mm )

21mH at 3.3A,
25S x 25T older quality re-cycled transformer iron,
156t x 1.32mm dia Cu, 0.24 ohms dcr.
gap = 0.54mm right across core, ( actual gap = 1.08mm ).

All gaps determined experimentally for highest inductance at
dc current nominated in test circuits equivalent to
actual amp operation conditions.

For example, to test the 4H and 60H chokes,
a test circuit was made as follows :-
+250Vdc supply with adjustable 50W resistance feed to the choke to set
the dc current,
then 100 ohms between choke and 0V so that choke Iac and Idc can both be
measured.
AC applied to top of choke from variac at 50Hz with an isolation electro
cap of 2,500uF.
A CRO was used to monitor choke current and distortion.

Inductance and gapping tests done at 10.0Vrms of 50Hz applied to choke,
with and without dc applied.
Phenomena observed. Without a gap and with no dc, inductance was high,
with iron µ = approx 650.
When dc was applied, inductance fell to 1/5 as the iron µ is affected by
dc magnetization.
As layers of notebook paper each 0.09mm thick were placed into the gap
right across the core,
the inductance with no dc reduced but tended not to fall when dc was
applied.
With dc applied, paper gapping was added and sheets recorded until peak
in inductance
was achieved. The final gap was that given by whatever number of paper
layers needed to give
a gap just above that for maximum L.
Choke bolts were tightened, E&I lams tapped up tight with dc applied,
and all with meters connected.
Chokes were soaked in varninsh, drained of excess and baked and
re-tested.
Using iron yokes to clamp chokes together made no difference to L.

The performance of the chokes with a much higher ac voltage applied
up to 150Vrms in the case of the 60H choke showed a change of inductance
of less than 2%.
The 4H chokes will have only about 2Vrms across them and at such a low
Vac,
their inductance will actually be slightly under 4H because of the
effect
of reducing iron µ with a reduced Vac applied across the choke.

((( Iron is queer material. Its permeability, µ, changes depending on
the applied Vac amplitude across the coil,
the frequency of the Vac, and the dc flow and the gap used.
Fully predicting an outcome with iron is virtually impossible,
and a frustration for engineers who like to work everything
out rather than rely on experimental methods to get a wanted outcome.
If you get poor results with chokes, you ain't working hard enough with
brain AND hands! )))



The 20mH chokes for the choke input supplies for the dc 845 cathodes
were tested with a 13.3Vac ac winding of a test tranny and a 35A diode
bridge,
and feeding a 22,000 uF cap.
Ripple voltage at the cap is less than 40mV, sufficiently low to stop
ac cathode current producing an anode hum signal.

The 20mH choke input supply is fairly well regulated, with 9.4Vdc at
3.3Adc, and 10.5Adc at 1Adc.
The choke input therefore will work with Chinese 845 with 3.3A needed
or with KR Audio 845 which I am fitting and which require only 1A for
cathode.

There is no need for a bleeder resistance.

The alternative to a choke input is a CLC input, but high peak charge
currents are needed,
and filtering isn't much better.

Using regulated supply means the C1 Vdc has to be dropped from about
15Vdc to 10Vdc at
and at 3.3Adc, some 32 watts of heat dissipation is required for the two
845.

The 20mH chokes tend to vibrate and hum when not clamped up tightly.
There is 6.0Vrms at 100Hz across the winding.
The varnishing will reduce the hum and vibration and they will
be clamped in rubber into the chassis away from iron surfaces, and with
aluminium yokes.
Using ac flow aranged in opposite directions should cancel most hum
generated.
There is little room to place the chokes in pots, which would have been
better,
but it takes up more precious space. I made an experimental steel sheet
pot
even with chamfered corners all around to better hug the shape of the
raw choke,
but still found no adequate space for them.

The conclusion I make from the above work is that for any amp maker
building any amp between 20 watts and 300 watts, all chokes needed can
be formed
from using 25 tongue material and mostly with a 25mm stack.
Increasing the stack height increases L linearly where the turns and gap
are the same.

Although there is a bunch of useful ideas and formula at my website,
always
ONLY RELY on actual test bench adjustments for gapping using a proper
test circuit
or with chokes connected in an amp under test.

To start a choke design, choose the wire size first according to the
wanted dc current allowing no more than 3A per sq.mm of copper area.

Consider the result of a short circuit in each case in the design.
Slow blo fuses must be used to protect chokes, and the fuse value
carefully
worked out so that they blow at twice the current rating for the wire.

For example, the above 60H choke has 0.2mm dia wire good for 94mA at
3A/sq.mm.
But I have 3 x EL84 in parallel, and if they go to a short,
there is a +750V supply plus 10k R in series with the choke and Idc
becomes 75mA.
The wire and choke will warm, but will survive.
I plan to run only 40mA throgh the choke.
I'll have a fuse as well, just incase the choke shorts to its
laminations and amp case.

Its unlikely because of the plasic bobbin and wrapping of winding in
carboard and mylar layers, all soaked well in varnish.

Weight of the final mono amp is simply bloody heavy.

This is good, and should prevent thieves hurrying away to quickly.

Patrick Turner.

[West]

"Patrick Turner" wrote in message
...


Raymond Koonce wrote:

Hi RATs,

I had the good fortune to attend the European Triode Festival in
Biezenmortel Netherlands a few days ago. It was a cool fest with about
80 participants. I made a web page of photos I shot there. Take a look
at http://www.timebanditaudio.com/etf2007/etf2007.html

Raymond

Some nice work done by diyers there but a lot is very poorly made
breadboard stuff. But they gotta start somewhere.

Lots of 845s in there.

I am proceeding seriously with constructing a
pair of monoblock 845 amps with two in parallel per channel.

So far I have power and OPTs both with 72mm stacks of 51mm tongue GOSS
lams,
and 5 chokes per channel, two 4H B+ chokes, one 60H choke for
dc supply to 3 paralleled EL84 SET drivers, and two 20mH chokes for the
pair of choke input
supply for 10Vdc x 3.3Adc heaters to 845.

I have so far 14 x 470uF x 400v rated caps.

I thought the chassis was big enough when I began but I wish it was 25
mm in each dimension....

Choke details as follows,

4H+ at 200mA,
32S x 25T, GOSS E&I.
1,400t x 0.4mm dia Cu, 30 ohms dcr.
gap = 0.18mm right across the core.( actual gap = 0.36mm )

4H+ at 200mA, but only 160mA used,
25S x 25T, GOSS E&I.
1.750t x 0.35mm Cu dia, 42 ohms dcr.
gap = 0.27mm right across core, ( actual gap = 0.54mm )

60H at 40mA,
32S x 25T GOSS E&I.
5,200t x 0.2mm Cu dia, 440 ohms dcr.
gap = 0.27mm right across core, ( actual gap = 0.54mm )

21mH at 3.3A,
25S x 25T older quality re-cycled transformer iron,
156t x 1.32mm dia Cu, 0.24 ohms dcr.
gap = 0.54mm right across core, ( actual gap = 1.08mm ).

All gaps determined experimentally for highest inductance at
dc current nominated in test circuits equivalent to
actual amp operation conditions.

For example, to test the 4H and 60H chokes,
a test circuit was made as follows :-
+250Vdc supply with adjustable 50W resistance feed to the choke to set
the dc current,
then 100 ohms between choke and 0V so that choke Iac and Idc can both be
measured.
AC applied to top of choke from variac at 50Hz with an isolation electro
cap of 2,500uF.
A CRO was used to monitor choke current and distortion.

Inductance and gapping tests done at 10.0Vrms of 50Hz applied to choke,
with and without dc applied.
Phenomena observed. Without a gap and with no dc, inductance was high,
with iron µ = approx 650.
When dc was applied, inductance fell to 1/5 as the iron µ is affected by
dc magnetization.
As layers of notebook paper each 0.09mm thick were placed into the gap
right across the core,
the inductance with no dc reduced but tended not to fall when dc was
applied.
With dc applied, paper gapping was added and sheets recorded until peak
in inductance
was achieved. The final gap was that given by whatever number of paper
layers needed to give
a gap just above that for maximum L.
Choke bolts were tightened, E&I lams tapped up tight with dc applied,
and all with meters connected.
Chokes were soaked in varninsh, drained of excess and baked and
re-tested.
Using iron yokes to clamp chokes together made no difference to L.

The performance of the chokes with a much higher ac voltage applied
up to 150Vrms in the case of the 60H choke showed a change of inductance
of less than 2%.
The 4H chokes will have only about 2Vrms across them and at such a low
Vac,
their inductance will actually be slightly under 4H because of the
effect
of reducing iron µ with a reduced Vac applied across the choke.

((( Iron is queer material. Its permeability, µ, changes depending on
the applied Vac amplitude across the coil,
the frequency of the Vac, and the dc flow and the gap used.
Fully predicting an outcome with iron is virtually impossible,
and a frustration for engineers who like to work everything
out rather than rely on experimental methods to get a wanted outcome.
If you get poor results with chokes, you ain't working hard enough with
brain AND hands! )))



The 20mH chokes for the choke input supplies for the dc 845 cathodes
were tested with a 13.3Vac ac winding of a test tranny and a 35A diode
bridge,
and feeding a 22,000 uF cap.
Ripple voltage at the cap is less than 40mV, sufficiently low to stop
ac cathode current producing an anode hum signal.

The 20mH choke input supply is fairly well regulated, with 9.4Vdc at
3.3Adc, and 10.5Adc at 1Adc.
The choke input therefore will work with Chinese 845 with 3.3A needed
or with KR Audio 845 which I am fitting and which require only 1A for
cathode.

There is no need for a bleeder resistance.

The alternative to a choke input is a CLC input, but high peak charge
currents are needed,
and filtering isn't much better.

Using regulated supply means the C1 Vdc has to be dropped from about
15Vdc to 10Vdc at
and at 3.3Adc, some 32 watts of heat dissipation is required for the two
845.

The 20mH chokes tend to vibrate and hum when not clamped up tightly.
There is 6.0Vrms at 100Hz across the winding.
The varnishing will reduce the hum and vibration and they will
be clamped in rubber into the chassis away from iron surfaces, and with
aluminium yokes.
Using ac flow aranged in opposite directions should cancel most hum
generated.
There is little room to place the chokes in pots, which would have been
better,
but it takes up more precious space. I made an experimental steel sheet
pot
even with chamfered corners all around to better hug the shape of the
raw choke,
but still found no adequate space for them.

The conclusion I make from the above work is that for any amp maker
building any amp between 20 watts and 300 watts, all chokes needed can
be formed
from using 25 tongue material and mostly with a 25mm stack.
Increasing the stack height increases L linearly where the turns and gap
are the same.

Although there is a bunch of useful ideas and formula at my website,
always
ONLY RELY on actual test bench adjustments for gapping using a proper
test circuit
or with chokes connected in an amp under test.

To start a choke design, choose the wire size first according to the
wanted dc current allowing no more than 3A per sq.mm of copper area.

Consider the result of a short circuit in each case in the design.
Slow blo fuses must be used to protect chokes, and the fuse value
carefully
worked out so that they blow at twice the current rating for the wire.

For example, the above 60H choke has 0.2mm dia wire good for 94mA at
3A/sq.mm.
But I have 3 x EL84 in parallel, and if they go to a short,
there is a +750V supply plus 10k R in series with the choke and Idc
becomes 75mA.
The wire and choke will warm, but will survive.
I plan to run only 40mA throgh the choke.
I'll have a fuse as well, just incase the choke shorts to its
laminations and amp case.

Its unlikely because of the plasic bobbin and wrapping of winding in
carboard and mylar layers, all soaked well in varnish.

Weight of the final mono amp is simply bloody heavy.

This is good, and should prevent thieves hurrying away to quickly.

Professor, would you mind sharing your progress. Not too many PPP 845S
discussed here. Sounds very exciting. Maybe this is what we could also use
for a healing.

west
Patrick Turner.

[tubegarden]

Hi RATs!

My latest is a touched up "Conar 300" - one 12AX7 and EL84 per
channel. I got it working with a few new caps.

When I switched the 6BQ5 (EL84) to triode, screen and plate tied, I
also replaced the std OPT with ubt-1.

Then there was hum, so, I added an external DC regulated filament
supply. The stock OPTs were small and probably couldn't pass the
60/120 Hz hum ...

The was still some hum happening, so I added an L-C-L-C filter to the
PS.

Then I shorted out the rectifier SS diode, so, I switched to an
external B+ supple, using 5AR4 rectifier.

Once I got a loose solder connection fixed, it played beautifully
until something shorted and blew the fuse. I switched back to the P-P
EL34 and will try again manana.

It sounded wonderful, for several minutes.

First circuit cludge in many, many moons

There is some magic left in this world ...

Happy Ears!

Al

[Patrick Turner]

tubegarden wrote:

Hi RATs!

My latest is a touched up "Conar 300" - one 12AX7 and EL84 per
channel. I got it working with a few new caps.

When I switched the 6BQ5 (EL84) to triode, screen and plate tied, I
also replaced the std OPT with ubt-1.

Then there was hum, so, I added an external DC regulated filament
supply. The stock OPTs were small and probably couldn't pass the
60/120 Hz hum ...

The was still some hum happening, so I added an L-C-L-C filter to the
PS.

Then I shorted out the rectifier SS diode, so, I switched to an
external B+ supple, using 5AR4 rectifier.

Once I got a loose solder connection fixed, it played beautifully
until something shorted and blew the fuse. I switched back to the P-P
EL34 and will try again manana.

It sounded wonderful, for several minutes.

First circuit cludge in many, many moons

There is some magic left in this world ...

Happy Ears!

The slow passage of time eventually prevents us from observing all we
should observe
when we should observe it.

Providing we do not kill ourselves as a result, we can hope to fix it
and
enjoy the wondererment.

Patrick Turner

Al

[Patrick Turner]

West wrote:

"Patrick Turner" wrote in message
...


Raymond Koonce wrote:

Hi RATs,

I had the good fortune to attend the European Triode Festival in
Biezenmortel Netherlands a few days ago. It was a cool fest with about
80 participants. I made a web page of photos I shot there. Take a look
at http://www.timebanditaudio.com/etf2007/etf2007.html

Raymond

Some nice work done by diyers there but a lot is very poorly made
breadboard stuff. But they gotta start somewhere.

Lots of 845s in there.

I am proceeding seriously with constructing a
pair of monoblock 845 amps with two in parallel per channel.

So far I have power and OPTs both with 72mm stacks of 51mm tongue GOSS
lams,
and 5 chokes per channel, two 4H B+ chokes, one 60H choke for
dc supply to 3 paralleled EL84 SET drivers, and two 20mH chokes for the
pair of choke input
supply for 10Vdc x 3.3Adc heaters to 845.

I have so far 14 x 470uF x 400v rated caps.

I thought the chassis was big enough when I began but I wish it was 25
mm in each dimension....

Choke details as follows,

4H+ at 200mA,
32S x 25T, GOSS E&I.
1,400t x 0.4mm dia Cu, 30 ohms dcr.
gap = 0.18mm right across the core.( actual gap = 0.36mm )

4H+ at 200mA, but only 160mA used,
25S x 25T, GOSS E&I.
1.750t x 0.35mm Cu dia, 42 ohms dcr.
gap = 0.27mm right across core, ( actual gap = 0.54mm )

60H at 40mA,
32S x 25T GOSS E&I.
5,200t x 0.2mm Cu dia, 440 ohms dcr.
gap = 0.27mm right across core, ( actual gap = 0.54mm )

21mH at 3.3A,
25S x 25T older quality re-cycled transformer iron,
156t x 1.32mm dia Cu, 0.24 ohms dcr.
gap = 0.54mm right across core, ( actual gap = 1.08mm ).

All gaps determined experimentally for highest inductance at
dc current nominated in test circuits equivalent to
actual amp operation conditions.

For example, to test the 4H and 60H chokes,
a test circuit was made as follows :-
+250Vdc supply with adjustable 50W resistance feed to the choke to set
the dc current,
then 100 ohms between choke and 0V so that choke Iac and Idc can both be
measured.
AC applied to top of choke from variac at 50Hz with an isolation electro
cap of 2,500uF.
A CRO was used to monitor choke current and distortion.

Inductance and gapping tests done at 10.0Vrms of 50Hz applied to choke,
with and without dc applied.
Phenomena observed. Without a gap and with no dc, inductance was high,
with iron µ = approx 650.
When dc was applied, inductance fell to 1/5 as the iron µ is affected by
dc magnetization.
As layers of notebook paper each 0.09mm thick were placed into the gap
right across the core,
the inductance with no dc reduced but tended not to fall when dc was
applied.
With dc applied, paper gapping was added and sheets recorded until peak
in inductance
was achieved. The final gap was that given by whatever number of paper
layers needed to give
a gap just above that for maximum L.
Choke bolts were tightened, E&I lams tapped up tight with dc applied,
and all with meters connected.
Chokes were soaked in varninsh, drained of excess and baked and
re-tested.
Using iron yokes to clamp chokes together made no difference to L.

The performance of the chokes with a much higher ac voltage applied
up to 150Vrms in the case of the 60H choke showed a change of inductance
of less than 2%.
The 4H chokes will have only about 2Vrms across them and at such a low
Vac,
their inductance will actually be slightly under 4H because of the
effect
of reducing iron µ with a reduced Vac applied across the choke.

((( Iron is queer material. Its permeability, µ, changes depending on
the applied Vac amplitude across the coil,
the frequency of the Vac, and the dc flow and the gap used.
Fully predicting an outcome with iron is virtually impossible,
and a frustration for engineers who like to work everything
out rather than rely on experimental methods to get a wanted outcome.
If you get poor results with chokes, you ain't working hard enough with
brain AND hands! )))



The 20mH chokes for the choke input supplies for the dc 845 cathodes
were tested with a 13.3Vac ac winding of a test tranny and a 35A diode
bridge,
and feeding a 22,000 uF cap.
Ripple voltage at the cap is less than 40mV, sufficiently low to stop
ac cathode current producing an anode hum signal.

The 20mH choke input supply is fairly well regulated, with 9.4Vdc at
3.3Adc, and 10.5Adc at 1Adc.
The choke input therefore will work with Chinese 845 with 3.3A needed
or with KR Audio 845 which I am fitting and which require only 1A for
cathode.

There is no need for a bleeder resistance.

The alternative to a choke input is a CLC input, but high peak charge
currents are needed,
and filtering isn't much better.

Using regulated supply means the C1 Vdc has to be dropped from about
15Vdc to 10Vdc at
and at 3.3Adc, some 32 watts of heat dissipation is required for the two
845.

The 20mH chokes tend to vibrate and hum when not clamped up tightly.
There is 6.0Vrms at 100Hz across the winding.
The varnishing will reduce the hum and vibration and they will
be clamped in rubber into the chassis away from iron surfaces, and with
aluminium yokes.
Using ac flow aranged in opposite directions should cancel most hum
generated.
There is little room to place the chokes in pots, which would have been
better,
but it takes up more precious space. I made an experimental steel sheet
pot
even with chamfered corners all around to better hug the shape of the
raw choke,
but still found no adequate space for them.

The conclusion I make from the above work is that for any amp maker
building any amp between 20 watts and 300 watts, all chokes needed can
be formed
from using 25 tongue material and mostly with a 25mm stack.
Increasing the stack height increases L linearly where the turns and gap
are the same.

Although there is a bunch of useful ideas and formula at my website,
always
ONLY RELY on actual test bench adjustments for gapping using a proper
test circuit
or with chokes connected in an amp under test.

To start a choke design, choose the wire size first according to the
wanted dc current allowing no more than 3A per sq.mm of copper area.

Consider the result of a short circuit in each case in the design.
Slow blo fuses must be used to protect chokes, and the fuse value
carefully
worked out so that they blow at twice the current rating for the wire.

For example, the above 60H choke has 0.2mm dia wire good for 94mA at
3A/sq.mm.
But I have 3 x EL84 in parallel, and if they go to a short,
there is a +750V supply plus 10k R in series with the choke and Idc
becomes 75mA.
The wire and choke will warm, but will survive.
I plan to run only 40mA throgh the choke.
I'll have a fuse as well, just incase the choke shorts to its
laminations and amp case.

Its unlikely because of the plasic bobbin and wrapping of winding in
carboard and mylar layers, all soaked well in varnish.

Weight of the final mono amp is simply bloody heavy.

This is good, and should prevent thieves hurrying away to quickly.

Professor, would you mind sharing your progress. Not too many PPP 845S
discussed here. Sounds very exciting. Maybe this is what we could also use
for a healing.

The 845 are not in PPP, which is Parallel Push Pull, which requires at
least 4 output tubes
as in the latest Quad 80.

I have my tubes in Parallel Single Ended, PSE.

The pain of building these amps does not teach us to grow, nor do I
think it
forms a healing experience. Like the steep slopes of the mountains I
ride up
on a bicycle, it merely teaches us that pain is ****ing painful
and nature is greater than ourselves, and the older one gets the better
one was,
so pedal like hell to get to the top to see the view; one might die on
the way and miss out.

The wonderment of a prolonged period of dying spread across maybe 85
years if lucky
is about equal to the wonderment of living the same length of time
simultaneously.

The most positive view is that glass is thus half empty while half full.

Pessimists amoung us would say no, at 60 a man is 3/4 done, with the
glass only 1/4 full,
and what's left in the glass is sour old wine to be sure.

But I don't suffer depression and the pessimism it brings...

We should be at ease with the onset of an absense of living or dying,
which is death.

And last month's Federal Election taught me again that when a man thinks
he
has reached his 3rd age of wisdom, the people around him can't wait to
not only
change and vote for the horrid foul opposition party, but vote you right
out of Parliment.

So the truly wise man understands that at least 1/2 the people around
think he's ****.

Patrick Turner.






west
Patrick Turner.

[Bob Woodward]

Patrick Turner wrote:

Raymond Koonce wrote:
Hi RATs,

I had the good fortune to attend the European Triode Festival in
Biezenmortel Netherlands a few days ago. It was a cool fest with about
80 participants. I made a web page of photos I shot there. Take a look
at http://www.timebanditaudio.com/etf2007/etf2007.html

Raymond

Some nice work done by diyers there but a lot is very poorly made
breadboard stuff. But they gotta start somewhere.

I think the diyers over there share a lot of knowledge and tube-audio
has started long ago in Europe.

The breadboard stuff shows people are working and improving constantly
not building products to sell but to enjoy experimenting.

I love to see breadboard stuff.

Robert

[Patrick Turner]

Bob Woodward wrote:

Patrick Turner wrote:

Raymond Koonce wrote:
Hi RATs,

I had the good fortune to attend the European Triode Festival in
Biezenmortel Netherlands a few days ago. It was a cool fest with about
80 participants. I made a web page of photos I shot there. Take a look
at http://www.timebanditaudio.com/etf2007/etf2007.html

Raymond

Some nice work done by diyers there but a lot is very poorly made
breadboard stuff. But they gotta start somewhere.

I think the diyers over there share a lot of knowledge and tube-audio
has started long ago in Europe.

The breadboard stuff shows people are working and improving constantly
not building products to sell but to enjoy experimenting.

I love to see breadboard stuff.

Robert

I used to do breadboarded stuff but i have to make a living
by selling what I make.
So what I make has to be optimised, with experiments all resolved, and
the circuit
made permanent in all metal casings but still with flexibility for
changes later.
So these days I work out what i think will work on paper,
and allow for trimming, and then choose a steel chassis big enough after
lot's of thought,
and I just build it so its like a factory made job.

The 845 amps I am making now can use 211,
and all that's needed is a link across a 1k cathode R on each output
tube.

This has to be carefully set up so a non technical owner is unlikely to
get it wrong.

Breadboard amps are far too dangerous to sell to anyone.

But for the home diyer they offer ultimate flexibility without
metalworking.

But real diyers won't mind working with a flat plate of at least
aluminium,
and when turned upside down with tubes poking down the citcuit can more
easily be worked on
than with tubes and R&C and rat's nest of wires all on one side.
The real diyer won't mind spending to buy a hole cutter punch ( Q-max )
for tube sockets.
If he wants to make the circuit permanent he mounts the plate on a
rectangle
formed by aluminium channel neatly mitred at corners and filed round and
screwed together
with a bottom cover.
This is also a good method for the real tradesman, as seen at
http://www.turneraudio.com.au/4+4-set-stereo-2a3.html


Just don't try to build a DA converter using only vacuum tubes on a
breadboard.

Or a cd player transport mech, or a TV set, you might become
confused......

Patrick Turner.

[Andre Jute]

On Dec 13, 3:35 am, Patrick Turner wrote:
Raymond Koonce wrote:

Hi RATs,

I had the good fortune to attend the European Triode Festival in
Biezenmortel Netherlands a few days ago. It was a cool fest with about
80 participants. I made a web page of photos I shot there. Take a look
athttp://www.timebanditaudio.com/etf2007/etf2007.html

Raymond

Some nice work done by diyers there but a lot is very poorly made
breadboard stuff. But they gotta start somewhere.

Jesus, Patrick. Some of those guys have forgotten more than about tube
amps than you know. Their interest is just different: they want to
make something fascinating, then move on to another fascinating
project, whereas you want to make something to sell.

Lots of 845s in there.

Many of those guys were regulars on the Sound List aka Joenet, where
the 845 was revered even above the 300B. And for good reason, I might
add. If I can have only one amp in heaven, it would have to be an 845.

I thought some of those breadboard construction ideas rather jolly.

I too build mostly breadboards; sometimes other people put them in
fancy cases. But I certainly proceed from the assumption that I want
to spend the minimum time on woodwork, and less time if possible on
metalwork. To facilitate that aim I work with the thinnest sheet of
ali that will hold a nut and bolt in, which turns out very
conveniently to be the covers for the Hammond ali 10x17x4 inch cases
that retail for for 12 dollars per cover. I buy the covers in bulk and
every year add just a few of the cases. The ali covers are 2mm (or
maybe 1.2mm, who cares) thick and very easy to mark out with a scribe
and punch and drill with titanium tools; amateurs should forget about
working steel unless they are masochists who like having their
knuckles busted. I back the ali cover sheet with 3/4in or 9mm ply cut
to size (I buy the backing ply sheets cut to the right size in bulk
too, pre-varnished to save yet more time), which also serves as a
drilling stop. After I have drilled all the holes in the ali plate, I
enlarge the holes in the wood to contain bolt heads. When the assembly
is finished, the ply is bolted to the ali plate to stiffen it so that
the weight of the transformers don't fold up the amp... This flatbase
assembly is then covered by the "case", standing on 6 or 10mm
standoffs for ventilation. The cases are recycled, the flat plates
just thrown away after the breadboard is finished with; there's very
little waste. Above all, it is a quick way of getting a working
prototype and very safe too because there is a cover of the correct
size instantly to hand. At
http://members.lycos.co.uk/fiultra/K...0T68MZ417A.jpg
you can see such a breadboard that I liked so much that I have kept it
for several years now.

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

[Patrick Turner]

Andre Jute wrote:

On Dec 13, 3:35 am, Patrick Turner wrote:
Raymond Koonce wrote:

Hi RATs,

I had the good fortune to attend the European Triode Festival in
Biezenmortel Netherlands a few days ago. It was a cool fest with about
80 participants. I made a web page of photos I shot there. Take a look
athttp://www.timebanditaudio.com/etf2007/etf2007.html

Raymond

Some nice work done by diyers there but a lot is very poorly made
breadboard stuff. But they gotta start somewhere.

Jesus, Patrick. Some of those guys have forgotten more than about tube
amps than you know. Their interest is just different: they want to
make something fascinating, then move on to another fascinating
project, whereas you want to make something to sell.

Jesus was a good man to be sure but the fact is that what I do is move
from one fascinating
project to the next. My wonderment is the same as the diyer brigade who
are not selling.

I try to share whatever expertise people may find in my procedures.

Most of our amp making attempts are comaparable with anyone else's,
and I have never shied away from comparing notes on how I might do
things.

So while I might seem to some as abrazive, I do have lots to offer
people...



Lots of 845s in there.

Many of those guys were regulars on the Sound List aka Joenet, where
the 845 was revered even above the 300B. And for good reason, I might
add. If I can have only one amp in heaven, it would have to be an 845.

If anyone should find out if the 845 is the king of the heap
then I will in the next few weeks!



I thought some of those breadboard construction ideas rather jolly.

I totally agree. Temporary though.

A long time ago in 1957, a guy who built a 400W PA amp using 10 x KT88
had his efforts pictured and fully described in Wireless World.
Guess what? the whole caboodle of parts was firmly screwed down to a
piece
of 25mm x 600mm plywood. All it needed was a U shaped peice of
industrial grade general purpose perforated sheet steel for a cove with
end stops and it
would have been quite safe to use.

But Somehow I think my customers wouldn't really like such very rugged
crudity.
So I go the extra $1,000 worth of expense to provide a fully metal
chassis
and powdercoated finish.



I too build mostly breadboards; sometimes other people put them in
fancy cases. But I certainly proceed from the assumption that I want
to spend the minimum time on woodwork, and less time if possible on
metalwork. To facilitate that aim I work with the thinnest sheet of
ali that will hold a nut and bolt in, which turns out very
conveniently to be the covers for the Hammond ali 10x17x4 inch cases
that retail for for 12 dollars per cover. I buy the covers in bulk and
every year add just a few of the cases. The ali covers are 2mm (or
maybe 1.2mm, who cares) thick and very easy to mark out with a scribe
and punch and drill with titanium tools; amateurs should forget about
working steel unless they are masochists who like having their
knuckles busted.

I recommended using sheet Al wherver possible in a later post.

For me steel is the only option.

The 845 amps am completeting are extremly heavy for a 50 watt amp.

If the chassis was Al, it'd have to be after the style of VAC amps, one
of which I have
here needing a considerable fix because of terrible circuit design.
But its chassis is 6mm Al plates, screwed together with 3mm allen screws
at 100mm centres
so that the screws are into the 6mm edge end on.
The 70+70 watt amp with 8 x 300B total is THE HEAVIEST box for 140 watts
that I have ever had the
displeasure of having to move around my workshop.
But together, my two 845 50w will have more total weight.

So steel becomes lighter than Al because its stronger.

Some amps with AL chassis would crumple into a mess if just dropped the
once.

So the more iron one puts on the chassis the more rigged the chassis has
to be and
so one simply has to spend a little longer working with drills, punches,
jig saws and be-burring tools.

I also cannot get a nice Al chassis made anywhere cheaply now because
all the
metalworkers in town seem to have evaporated or are s busy the lead time
is 4 months
like it is with me when someone orders anything from me.
When i do use Al, The top plate might be but the side are from 3mm wall
thick channels available in a range of
sizes. This is usually as good as steel for a 2 x 25 watt PP amp, or a
couple of SE channels such as at
http://www.turneraudio.com.au/4+4-set-stereo-2a3.html

Steel channel plus AL toplates are used my 300 watters which have
separate chassis for each audio channel and power supplies for each;
so 4 chassis at 25kg each.

An amp would still make a mess of itself falling off a bench though....



I back the ali cover sheet with 3/4in or 9mm ply cut
to size (I buy the backing ply sheets cut to the right size in bulk
too, pre-varnished to save yet more time), which also serves as a
drilling stop. After I have drilled all the holes in the ali plate, I
enlarge the holes in the wood to contain bolt heads. When the assembly
is finished, the ply is bolted to the ali plate to stiffen it so that
the weight of the transformers don't fold up the amp... This flatbase
assembly is then covered by the "case", standing on 6 or 10mm
standoffs for ventilation. The cases are recycled, the flat plates
just thrown away after the breadboard is finished with; there's very
little waste. Above all, it is a quick way of getting a working
prototype and very safe too because there is a cover of the correct
size instantly to hand. At
http://members.lycos.co.uk/fiultra/K...0T68MZ417A.jpg
you can see such a breadboard that I liked so much that I have kept it
for several years now.

Not bad. Its your own though, and maybe you'd have trouble trying to
sell it to get a return on the costs...

I made a JBS amp in about 3 weeks seen also at
http://www.turneraudio.com.au/2323-t...ated-6cm5.html
Its shown with cover off at the bottom of the page.
It'd also bend a bit if dropped off a bench.

The ideal amp should withstand a fall of 3 feet,
and some might say it matters not if the amp proceeds through the floor,
and astonishes people having dinner immediately below,
providing do damage occurs to the amp.

The cat under the dinner table would be somewhat alarmed......

Patrick Turner.



Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

[Andre Jute]

On Dec 15, 11:45 am, Patrick Turner wrote:
Andre Jute wrote:

Patrick wrote:
I also cannot get a nice Al chassis made anywhere cheaply now because
all the
metalworkers in town seem to have evaporated or are s busy the lead time
is 4 months
like it is with me when someone orders anything from me.
When i do use Al, The top plate might be but the side are from 3mm wall
thick channels available in a range of
sizes. This is usually as good as steel for a 2 x 25 watt PP amp, or a
couple of SE channels such as athttp://www.turneraudio.com.au/4+4-set-stereo-2a3.html

For anything that tidy with tubes on top I'd have to charge a lot of
money, when then requires putting a nice piece of wood on the facia,
which again bumps up the price. I tend these days to put everything,
including tubes, under a cover, to avoid falling foul of consumer
protection legislation and even the insurance companies.

Steel channel plus AL toplates are used my 300 watters which have
separate chassis for each audio channel and power supplies for each;
so 4 chassis at 25kg each.

Yeah, my T199 Millennium's end 80W PSE Class A1 from SV572-3 weighed
125 pounds per channel. They were built that way to avoid HT
powercords and even 150V+ signal at pretty elevated current running
all over the place. Since they were used mostly in their SE 25W mode,
I eventually broke them up as simply too heavy.

An amp would still make a mess of itself falling off a bench though....

Even a "small" tube amp might make a mess of the bones in your foot.

I back the ali cover sheet with 3/4in or 9mm ply cut
to size (I buy the backing ply sheets cut to the right size in bulk
too, pre-varnished to save yet more time), which also serves as a
drilling stop. After I have drilled all the holes in the ali plate, I
enlarge the holes in the wood to contain bolt heads. When the assembly
is finished, the ply is bolted to the ali plate to stiffen it so that
the weight of the transformers don't fold up the amp... This flatbase
assembly is then covered by the "case", standing on 6 or 10mm
standoffs for ventilation. The cases are recycled, the flat plates
just thrown away after the breadboard is finished with; there's very
little waste. Above all, it is a quick way of getting a working
prototype and very safe too because there is a cover of the correct
size instantly to hand. At
http://members.lycos.co.uk/fiultra/K...0T68MZ417A.jpg
you can see such a breadboard that I liked so much that I have kept it
for several years now.

Not bad. Its your own though, and maybe you'd have trouble trying to
sell it to get a return on the costs...

That's actually a transformer coupled 300B base plate you're looking
at, the potato WE417A amp being made by removing the 300B and the IST
and rewiring the Lundahl power trx. When I sell T39 (which is a very
silent 3.8W RC coupled 417A/300B SE intended for horns or very high
efficiency speakers, see http://members.lycos.co.uk/fiultra/T...trafi-crct.jpg
), I get that T68bis pattern professionally laser cut in 3mm tellurium
copper sheet. That was covered in the past (craftsman now retired) by
a solid-wood or veneered wooden box with a couple of inset copper
pieces to the front and back, or a polished stainless box simply
because, like you, I cannot get nice ali or steel boxes made to size.
I can't even get anything else except very thin stuff nicely bent any
more without going to a guy eighty miles away; the best I can do is
get a garden furniture maker eighty miles away the other side to weld
up some iron angle, pretty rough stuff...

I sold two of the T68bis but I had the copper plates cut to take 300B
as well, just in case the owners get fed up with the very low output
from the single 417A and decide to return them for upgrading.
Essentially, a potato amp should be a gimmick for poor audiophiles,
whereas my T68 is a novelty for plutocrats, probably the most
expensive amp per watt available anywhere... And it doesn't do too
badly on the Dunker Factor either, which measures goodness as mo'
pounds of weight per watt on the assumption that mo' iron is betta
iron.

I gave Mick a pair of WE417A for a potato amp but the last time he was
on RAT he said he thought they were too good for that; he was planning
to use them as high-current drivers in another amp.

I made a JBS amp

The T68 isn't a junkbox amp. It is made with all new parts, and only
the best: Lundahl iron, Solen caps, Cardas wire and connectors. I
don't build junkbox amps; it isn't worth my time and effort.

Yo, Patrick, I find it heartening that you're having as much trouble
as I am getting a decent case made. For a while I though it was just
me being overly finicky... A couple of years ago I took apart a steel
case, resoldered it straight, filled and smoothed it off, and took it
back to the maker as a sample of acceptable quality; he looked me
straight in the eye and said, "It's a waste of time poncing around
with metrics. To the nearest inch is good enough."

For a while I could get cases from my Japanese mate, which he had made
in China to his exacting specifications. They were pretty good, but
only because the guy is in China with his valve tester and his
micrometer every other week, personally supervising, and he doesn't
mind paying for wastage as long as the final job is done perfectly.
But even the best Chinese casework, made under the supervision of an
obsessive, is still not crafted with the punctilio of the cases he
previously had made in Japan by a shop that makes bike parts and grew
too expensive for him, with lead times of fifteen months the last time
I heard (Boeing can deliver a big jet in less time than that!).

Just for the record: Proper casework has no self-tapping metal screws
(1) but instead formed and threaded pressouts for proper bolts, and no
exposed edges, and no rough corners, and all cutouts are smoothed off
to both sides. That is an absolute minimum.

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

(1) I was horrified by your report in another thread about an American
amp maker with pretty stiff prices whose casework depends on
selftappers edgewise into 6mm ali.

[David R Brooks]

Andre Jute wrote:
On Dec 15, 11:45 am, Patrick Turner wrote:
Andre Jute wrote:

Patrick wrote:
I also cannot get a nice Al chassis made anywhere cheaply now because
all the
metalworkers in town seem to have evaporated or are s busy the lead time
is 4 months
like it is with me when someone orders anything from me.
When i do use Al, The top plate might be but the side are from 3mm wall
thick channels available in a range of
sizes. This is usually as good as steel for a 2 x 25 watt PP amp, or a
couple of SE channels such as athttp://www.turneraudio.com.au/4+4-set-stereo-2a3.html

For anything that tidy with tubes on top I'd have to charge a lot of
money, when then requires putting a nice piece of wood on the facia,
which again bumps up the price. I tend these days to put everything,
including tubes, under a cover, to avoid falling foul of consumer
protection legislation and even the insurance companies.

Steel channel plus AL toplates are used my 300 watters which have
separate chassis for each audio channel and power supplies for each;
so 4 chassis at 25kg each.

Yeah, my T199 Millennium's end 80W PSE Class A1 from SV572-3 weighed
125 pounds per channel. They were built that way to avoid HT
powercords and even 150V+ signal at pretty elevated current running
all over the place. Since they were used mostly in their SE 25W mode,
I eventually broke them up as simply too heavy.

An amp would still make a mess of itself falling off a bench though....

Even a "small" tube amp might make a mess of the bones in your foot.

I back the ali cover sheet with 3/4in or 9mm ply cut
to size (I buy the backing ply sheets cut to the right size in bulk
too, pre-varnished to save yet more time), which also serves as a
drilling stop. After I have drilled all the holes in the ali plate, I
enlarge the holes in the wood to contain bolt heads. When the assembly
is finished, the ply is bolted to the ali plate to stiffen it so that
the weight of the transformers don't fold up the amp... This flatbase
assembly is then covered by the "case", standing on 6 or 10mm
standoffs for ventilation. The cases are recycled, the flat plates
just thrown away after the breadboard is finished with; there's very
little waste. Above all, it is a quick way of getting a working
prototype and very safe too because there is a cover of the correct
size instantly to hand. At
http://members.lycos.co.uk/fiultra/K...0T68MZ417A.jpg
you can see such a breadboard that I liked so much that I have kept it
for several years now.
Not bad. Its your own though, and maybe you'd have trouble trying to
sell it to get a return on the costs...

That's actually a transformer coupled 300B base plate you're looking
at, the potato WE417A amp being made by removing the 300B and the IST
and rewiring the Lundahl power trx. When I sell T39 (which is a very
silent 3.8W RC coupled 417A/300B SE intended for horns or very high
efficiency speakers, see http://members.lycos.co.uk/fiultra/T...trafi-crct.jpg
), I get that T68bis pattern professionally laser cut in 3mm tellurium
copper sheet. That was covered in the past (craftsman now retired) by
a solid-wood or veneered wooden box with a couple of inset copper
pieces to the front and back, or a polished stainless box simply
because, like you, I cannot get nice ali or steel boxes made to size.
I can't even get anything else except very thin stuff nicely bent any
more without going to a guy eighty miles away; the best I can do is
get a garden furniture maker eighty miles away the other side to weld
up some iron angle, pretty rough stuff...

I sold two of the T68bis but I had the copper plates cut to take 300B
as well, just in case the owners get fed up with the very low output
from the single 417A and decide to return them for upgrading.
Essentially, a potato amp should be a gimmick for poor audiophiles,
whereas my T68 is a novelty for plutocrats, probably the most
expensive amp per watt available anywhere... And it doesn't do too
badly on the Dunker Factor either, which measures goodness as mo'
pounds of weight per watt on the assumption that mo' iron is betta
iron.

I gave Mick a pair of WE417A for a potato amp but the last time he was
on RAT he said he thought they were too good for that; he was planning
to use them as high-current drivers in another amp.

I made a JBS amp

The T68 isn't a junkbox amp. It is made with all new parts, and only
the best: Lundahl iron, Solen caps, Cardas wire and connectors. I
don't build junkbox amps; it isn't worth my time and effort.

Yo, Patrick, I find it heartening that you're having as much trouble
as I am getting a decent case made. For a while I though it was just
me being overly finicky... A couple of years ago I took apart a steel
case, resoldered it straight, filled and smoothed it off, and took it
back to the maker as a sample of acceptable quality; he looked me
straight in the eye and said, "It's a waste of time poncing around
with metrics. To the nearest inch is good enough."

For a while I could get cases from my Japanese mate, which he had made
in China to his exacting specifications. They were pretty good, but
only because the guy is in China with his valve tester and his
micrometer every other week, personally supervising, and he doesn't
mind paying for wastage as long as the final job is done perfectly.
But even the best Chinese casework, made under the supervision of an
obsessive, is still not crafted with the punctilio of the cases he
previously had made in Japan by a shop that makes bike parts and grew
too expensive for him, with lead times of fifteen months the last time
I heard (Boeing can deliver a big jet in less time than that!).

Just for the record: Proper casework has no self-tapping metal screws
(1) but instead formed and threaded pressouts for proper bolts, and no
exposed edges, and no rough corners, and all cutouts are smoothed off
to both sides. That is an absolute minimum.

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

(1) I was horrified by your report in another thread about an American
amp maker with pretty stiff prices whose casework depends on
selftappers edgewise into 6mm ali.

There's a place here in Perth (yes, I know that's a long way away from
many readers!), who does good stuff using CNC equipment. The onus is on
the customer to design & supply CAD files (I used Solid Edge), but the
work is then accurate. He will TIG the joints.
Expensive, yes.
Name: Custom Aluminium.

[Patrick Turner]

Andre Jute wrote:

On Dec 15, 11:45 am, Patrick Turner wrote:
Andre Jute wrote:

Patrick wrote:
I also cannot get a nice Al chassis made anywhere cheaply now because
all the
metalworkers in town seem to have evaporated or are s busy the lead time
is 4 months
like it is with me when someone orders anything from me.
When i do use Al, The top plate might be but the side are from 3mm wall
thick channels available in a range of
sizes. This is usually as good as steel for a 2 x 25 watt PP amp, or a
couple of SE channels such as athttp://www.turneraudio.com.au/4+4-set-stereo-2a3.html

For anything that tidy with tubes on top I'd have to charge a lot of
money, when then requires putting a nice piece of wood on the facia,
which again bumps up the price. I tend these days to put everything,
including tubes, under a cover, to avoid falling foul of consumer
protection legislation and even the insurance companies.

I get asked NOT to place a cover over tube amps.

In the case of the 2A3 amps I built at the above URL, I was not
compelled to
supply a cover over the tubes, and didn't feel it made the amps much
safer; only
2A3s exposed to the bruises of life, and no worse than two naked 25 watt
light bulbs with 240Vrms.

But when asked last week to not supply grilles over the new 845 amps I
refused,
saying that there IS too much danger, and likelyhood of damage,
and considering a single KR845 is worth usd $370 ( $1,780 for the two
monoblocs ),
landed at my door, its worth supplying $300 worth of grilles.
I have not finalised the design of them because the amps seem so ferkin
heavy, but something
welded from 10mm round bar and painted black will probably do.

I don't want to get relieved of my house ownership if **** happens
and smart lawyers are brought in to clean me out.


Steel channel plus AL toplates are used my 300 watters which have
separate chassis for each audio channel and power supplies for each;
so 4 chassis at 25kg each.

Yeah, my T199 Millennium's end 80W PSE Class A1 from SV572-3 weighed
125 pounds per channel. They were built that way to avoid HT
powercords and even 150V+ signal at pretty elevated current running
all over the place. Since they were used mostly in their SE 25W mode,
I eventually broke them up as simply too heavy.

An amp would still make a mess of itself falling off a bench though....

Even a "small" tube amp might make a mess of the bones in your foot.

!

I back the ali cover sheet with 3/4in or 9mm ply cut
to size (I buy the backing ply sheets cut to the right size in bulk
too, pre-varnished to save yet more time), which also serves as a
drilling stop. After I have drilled all the holes in the ali plate, I
enlarge the holes in the wood to contain bolt heads. When the assembly
is finished, the ply is bolted to the ali plate to stiffen it so that
the weight of the transformers don't fold up the amp... This flatbase
assembly is then covered by the "case", standing on 6 or 10mm
standoffs for ventilation. The cases are recycled, the flat plates
just thrown away after the breadboard is finished with; there's very
little waste. Above all, it is a quick way of getting a working
prototype and very safe too because there is a cover of the correct
size instantly to hand. At
http://members.lycos.co.uk/fiultra/K...0T68MZ417A.jpg
you can see such a breadboard that I liked so much that I have kept it
for several years now.

Not bad. Its your own though, and maybe you'd have trouble trying to
sell it to get a return on the costs...

That's actually a transformer coupled 300B base plate you're looking
at, the potato WE417A amp being made by removing the 300B and the IST
and rewiring the Lundahl power trx. When I sell T39 (which is a very
silent 3.8W RC coupled 417A/300B SE intended for horns or very high
efficiency speakers, see http://members.lycos.co.uk/fiultra/T...trafi-crct.jpg
), I get that T68bis pattern professionally laser cut in 3mm tellurium
copper sheet. That was covered in the past (craftsman now retired) by
a solid-wood or veneered wooden box with a couple of inset copper
pieces to the front and back, or a polished stainless box simply
because, like you, I cannot get nice ali or steel boxes made to size.

Well one local company did offer its services two years ago.
The guy was 63, and had 3 sons with a lots of businesses,
one of which specialized in stainless steelware made to order.
But he doesn't follow up phone calls, and has let his website go off
line,
and last time I spoke to him he seemed to be rather slow,
and frankly I though he'd lost it. Anyway, prices would have been
horrendous.
"Professionals" are mostly a POX. They add a zero to a tradesman's
price,
just when it isn't wanted...

Blokes actually on the tools in the workshop
all like to get average weekly earnings for metalwork at least ( aud
$45k pa in Oz now ).
Their boss has to add heaps of on-costs because of profits, power, rent,
power etc.
But I only make 7k most years, and if I use ANY subcontractors at all
they clean me out and I work for nothing. Its because NOBODY ever offers
to pay me
as i should be paid, ie, as well as a tradesman. They only want to pay
me as they would an artist,
ie, a mixture of peanuts and lip service, so I am forced to sell for 1/2
the
high end price sometimes, when I should be paid twice as much.
I have to pay lots more for material and the time spent is huge
for a one off where all the R&D that a company might use for a bath of
1,000 amps
is the same as I use for just ONE amp.

And when I invested $3k in pre-made steel chassis equal to Quad
standards with tranny pots 3 years ago,
it seems that was a complete waste because I received not a single
order. They wanted amps
which didn't suit the chassis I had specially made to suit 4 different
types of amps.


I can't even get anything else except very thin stuff nicely bent any
more without going to a guy eighty miles away; the best I can do is
get a garden furniture maker eighty miles away the other side to weld
up some iron angle, pretty rough stuff...

I sold two of the T68bis but I had the copper plates cut to take 300B
as well, just in case the owners get fed up with the very low output
from the single 417A and decide to return them for upgrading.
Essentially, a potato amp should be a gimmick for poor audiophiles,
whereas my T68 is a novelty for plutocrats, probably the most
expensive amp per watt available anywhere... And it doesn't do too
badly on the Dunker Factor either, which measures goodness as mo'
pounds of weight per watt on the assumption that mo' iron is betta
iron.

I gave Mick a pair of WE417A for a potato amp but the last time he was
on RAT he said he thought they were too good for that; he was planning
to use them as high-current drivers in another amp.

I made a JBS amp

The T68 isn't a junkbox amp. It is made with all new parts, and only
the best: Lundahl iron, Solen caps, Cardas wire and connectors. I
don't build junkbox amps; it isn't worth my time and effort.

It isn't hard to get amazing sound fromk triodes with so-so parts
IF one knows what one is doing. I sure proved all that to
the audio club on more than one occasion....


Yo, Patrick, I find it heartening that you're having as much trouble
as I am getting a decent case made. For a while I though it was just
me being overly finicky... A couple of years ago I took apart a steel
case, resoldered it straight, filled and smoothed it off, and took it
back to the maker as a sample of acceptable quality; he looked me
straight in the eye and said, "It's a waste of time poncing around
with metrics. To the nearest inch is good enough."

Yup, the 845 pair of chassis did have slight out of squareness of about
1.5mm on plan,
and one side is 1mm higher than the other. Nobody will notice because
you cannot
see the errors. Barely within tolerances. Solid enough though.
But it put me off using that guy again. Even with his
factory tools he couldn't keep it any squarer than I can using
primitive blocks of wood, G-cramps, and a lump hammer and blocks of wood
to bend the metal.



For a while I could get cases from my Japanese mate, which he had made
in China to his exacting specifications. They were pretty good, but
only because the guy is in China with his valve tester and his
micrometer every other week, personally supervising, and he doesn't
mind paying for wastage as long as the final job is done perfectly.
But even the best Chinese casework, made under the supervision of an
obsessive, is still not crafted with the punctilio of the cases he
previously had made in Japan by a shop that makes bike parts and grew
too expensive for him, with lead times of fifteen months the last time
I heard (Boeing can deliver a big jet in less time than that!).

Just for the record: Proper casework has no self-tapping metal screws
(1) but instead formed and threaded pressouts for proper bolts, and no
exposed edges, and no rough corners, and all cutouts are smoothed off
to both sides. That is an absolute minimum.

The metalwork should FEEL GOOD.
And look neat, tidy, with not a single 90 degree edge anywhere.
Self tappers are OK if they secure items concealed 1mm sheet steel.
The Japs have been doing it for years in countless amps.
But external case securing screws should all be metal thread.
The VAC amp uses high tensile 3mm machine Allen screws with plenty of
penetration to edges of 6mm Al plates; not a bad way to do it so one
avoids
having to use steel angles or bars at all metalwork corners, which BTW
WOULD
be stronger....
If a VAC drops off a bench, maybe those 3mm screws shear off, and then
you have to
extract the buried part of the screw..YUK.

I dunno how much 2 x 70 watts from VAC costs these days; I assume its
next
to a king's ranson though.

But I raise my hat to those who sell such overpriced and expensive
equipments to the
gullible public.
Imagine if they left a zero off the price and charged like a GOOD
tradesman.
I'd never compete with them at all.

People come to me partially because they know the alternative costs so
much more,
and they realize the alterive's high price merely buys a BMW for the
boss,
and does not give them any more audio quality than I would provide.

Trouble is I am left with a price from which I find it difficult to
afford a bicycle.

They are extremely lucky I enjoy riding one, and dislike riding
expensive shielas.

Patrick Turner.



Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

(1) I was horrified by your report in another thread about an American
amp maker with pretty stiff prices whose casework depends on
selftappers edgewise into 6mm ali.

[News Client]

"Andre Jute" wrote in message ...
Yeah, my T199 Millennium's end 80W PSE Class A1 from SV572-3 weighed
125 pounds per channel...

When I sell T39...

I sold two of the T68bis...

I am skeptical. Please post photographs. Contact information for some of your
customers would be even more helpful (surely they would be proud to share the
details with interested third parties).

[mick]

On Sat, 15 Dec 2007 08:25:04 -0800, Andre Jute wrote:

snip

I gave Mick a pair of WE417A for a potato amp but the last time he was
on RAT he said he thought they were too good for that; he was planning
to use them as high-current drivers in another amp.


Still ongoing... :-)

First pics of new speakers on u.r.a

snip

(1) I was horrified by your report in another thread about an American
amp maker with pretty stiff prices whose casework depends on selftappers
edgewise into 6mm ali.


You probably know but, for the benefit of others, there are self-tappers
& self tappers! The very coarse ones are more correctly named "sheet
screws" and are remarkably good when fastening into steel or ali sheet
(but be careful not to overtighten as they can tear ali). There are also
some which look a lot like standard machine screws, but which usually
have a "trilobal" cross section if viewed from the end and often a slight
leading taper. These are hard to very hard screws and actually cut a
standard thread in the material when inserted correctly. You can put a
standard machine screw in afterward if you so wish. This sort shouldn't
have any problem into 6mm ali edges if the screw size is small (say M2.5
or M3 at most). The resulting assembly could be very strong if correctly
designed. They are useless into thin (say 2mm steel or 3mm ali) sheet
as they can't cut enough threads.

--
Mick (Working in a M$-free zone!)
Web: http://www.nascom.info http://mixpix.batcave.net