[DM]

Question from a tube novice.. I've got a Traynor YCS50 Combo & I was
told by Traynor support that it doesn't need to be rebias as long as I
use 5881/6L6 power tubes regradless of the brand or type? I'm kinda
skeptical cuz' I ask every Guitar forum and they say it needs to be
rebias..

What consequences if I don't rebias after tube change? thanks!

[Phil Allison[_3_]]

"DM"

Question from a tube novice..

** Question form a tube bull**** artist is more like it.

I've got a Traynor YCS50 Combo & I was
told by Traynor support that it doesn't need to be rebias as long as I
use 5881/6L6 power tubes regradless of the brand or type?


** That is NOT the same story you posted on alt.guitar amps.

" I e-mailed traynor support and they mentioned I cannot use a non-
12ax7 pre's on my Traynor YCS50(?) they also mentioned that the
Amp does it self bias(?) I don't have to bias if I change the power
tubes. So I can just pull the old Sovtek 5881's and put a 6L/EL34
group powert tubes!? "

In any case, the question is absurd cos the amps come with user adjustable
bias controls fitted and instructions for doing the job.


..... Phil

[Patrick Turner]

On Jun 13, 4:38*pm, "Phil Allison" wrote:
"DM"

Question from a tube novice..

** Question form a tube bull**** artist is more like it.

I've got a Traynor YCS50 Combo & I was
told by Traynor support that it doesn't need to be rebias as long as I
use 5881/6L6 power tubes regradless of the brand or type?

** That is *NOT *the same story you posted on alt.guitar amps.

" I e-mailed traynor support and they mentioned I cannot use a non-
12ax7 pre's on my Traynor YCS50(?) they also mentioned that the
Amp does it self bias(?) I don't have to bias if I change the power
tubes. So I can just pull the old *Sovtek 5881's and put a 6L/EL34
group powert tubes!? * "

In any case, the question is absurd cos the amps come with user adjustable
bias controls fitted and instructions for doing the job.

.... * Phil

Perhaps the original poster needs to learn to bias his amps but for
that a brain which can understand basic electronics is required. But I
have found by experience that musicians are artists who may find it
easy to play a tune I find difficult but they really struggle with
basic logic or the slightest technical issue. Not one guitar amp
manufacturer has ever put a musician proof biasing scheme under the
chassis of their creation. Shame on Fender and Marshal.

But it IS TRUE that if one inserts EL34 or 6CA7 where there were
6L6/5881/KT66/KT88/6550 then the amp does need to have its bias
adjusted. Same goes when you remove EL34 and insert the 6L6 etc list
of tubes.

In my experience I have also found that all large octal output tubes
in the family 6L6/5881/KT66/KT88/6550 can be interchanged and biasing
should be *approximately* same for any of them, but *balancing* the
bias needs to be done whenever one tube is replaced by another, if
there is a balancing pot. The **exception** are the EL34 or 6CA7 and
you must not pull out a PAIR of 6L6 and just plug in EL34/6CA7 without
adjusting the overall bias level for both tubes, or vice versa. Some
amp makers provide for this with a switch or a resistor with link to
be connected or not connected. The manufacturers' manual should have
instructions about this.

The God Of Triodes was born sometime in Heaven in about 1869. Father
was Main God, mother was spiritual harlot, Electricia, who was very
hot wired. The GOT became slightly mature enough to deal with letting
mankind understand secrets of electronics at around 1890, when it
looked like man might advance a little too swiftly from a God's point
of view. The GOT was and remains a bit of a ******* because when he
should have steered mankind straight away to digital **** and
transistors with self biasing elements within them, he didn't, and he
let mankind invent things like tubes which have caused biasing
confusion and a few house & venue fires during the last 100 years,
plus some dazed musos with pocket fulls of spare 6L6.

Patrick Turner.

[Bret L]

On Jun 13, 3:17*am, Patrick Turner wrote:
On Jun 13, 4:38*pm, "Phil Allison" wrote:




.... * Phil

Perhaps the original poster needs to learn to bias his amps but for
that a brain which can understand basic electronics is required. But I
have found by experience that musicians are artists who may find it
easy to play a tune I find difficult but they really struggle with
basic logic or the slightest technical issue. Not one guitar amp
manufacturer has ever put a musician proof biasing scheme under the
chassis of their creation. Shame on Fender and Marshal.

Sounds like a Market Op for you there Patrick.

[Ian Iveson]

Patrick Turner wrote :

Perhaps the original poster needs to learn to bias his amps
but for
that a brain which can understand basic electronics is
required. But I
have found by experience that musicians are artists who may
find it
easy to play a tune I find difficult but they really
struggle with
basic logic or the slightest technical issue. Not one guitar
amp
manufacturer has ever put a musician proof biasing scheme
under the
chassis of their creation. Shame on Fender and Marshal.


***Surprising. Why not? It's a while since I've seen a new
guitar amp, but I would have thought some of them might have
made an attempt by now. Surely they're full of DSP and
SS-controlled switching these days? I'd kind of assumed that
an intelligent amplifier would look after itself.

***I'm in the process of adding automated bias adjustment to
my amps, which is why I'm moaning about tiny SMT components.
The remote-controlled pre uses an MCU capable of running a
small country, so it might as well make itself useful. Since
the controller also handles power-on and power-off
sequencing, bias adjustment should fit in neatly, leaving
the digital circuits dormant when the amp's in use. It'll
wake up for the usual remote functions like volume control
and source select, or for alarm conditions such as an
out-of-range bias current. Otherwise it's non-invasive.

***If anyone's interested in sharing what I've done and
helping put it to good use, BTW, let me know. PCB design,
and finalising the analogue part of the bias circuit, are
the main source of angst ATM, in addition to the SMT issue.
It's a good vehicle for learning about MCUs, digital
circuits, and programming. I hope. OTOH, that's not what ppl
are here for, I guess.

***The other big thing for the future-if-there-is-one is
switch-mode power supplies for HT and heaters. Too scary for
me to experiment with. Books may aid the understanding, but
they don't seem to stop the smoke.

Ian

[Phil Allison[_3_]]

"Ian Iveson"

Patrick Turner wrote :

Not one guitar amp
manufacturer has ever put a musician proof biasing scheme under the
chassis of their creation. Shame on Fender and Marshal.


***Surprising. Why not?

** Because NOTHING can be made musician proof !!!

Eg. When the spigot breaks off a 6L6, musos plug them in any way it goes.


It's a while since I've seen a new guitar amp, but I would have thought
some of them might have made an attempt by now.

** A number of tube guitar amps DO have self biassing.

Egs:

All the ones that use cathode resistor bias - ie Vox AC30 and clones and
most single output tube amps.

Ones that use direct transistor drive to the output tube cathodes - ie
Peavey Heritage series and most Music Man models.

But it is still a VERY bad idea to let musos chose and install their own
tubes.


..... Phil

[Patrick Turner]

On Jun 14, 2:22*pm, "Phil Allison" wrote:
"Ian Iveson"

Patrick Turner wrote :

Not one guitar amp
manufacturer has ever put a musician proof biasing scheme under the
chassis of their creation. Shame on Fender and Marshal.

***Surprising. Why not?

** Because *NOTHING can be made musician proof *!!!

Eg. When the spigot breaks off a 6L6, musos plug them in any way it goes.

Well indeed such optimistic problem solving can lead to a big bill or
smoke or both.

I have not got around to working out how many deadly positions there
are for a 6L6 when there is no guide spigot.

Often the fuse is the last thing to blow.

But some over current sensing here and there would save the day.

The biggest killer of output and power trannies is saturating tubes
before they melt down when the current overheats everything. But I
avoid this problem in all my tube amps I build with simple current
sensing on each cathode so that if one or more output cathodes pulls
more than twice the bias current for longer than 4 seconds the amp
turns off.

This might upset the musos at a gig when they drive the output stage
deep into class C.

But with 6L6 or 6550 the threshold can be 200mA and that should not be
a nuisance.

A guy once sent me two amps with a pair of 2A3 and kitted out with
potted Tango trannies. Both power tranny primaries went open after he
plugged in the 2A3 the wrong way because the dopey Chines makers of
the tube sockets did not make 2 holes for anode and grid small enough
to keep the larger pins for the cathode out. The guy just sat there
gazing and wondering why the power trannies got hot with no music -
and then they cooled down, and still no music.
There was cathode biasing which did not save the power trannies.
I have seen Quad-II amps have troubles when an ESL57 panel starts
arcing above some low level threshold which of course is way too low
for anyone's kids. The brats like turning it up, and up and up even
more.


It's a while since I've seen a new guitar amp, but I would have thought
some of them might have made an attempt by now.

** A number of tube guitar amps *DO have self *biassing.

Egs:

All the ones that use cathode resistor bias - *ie Vox AC30 and clones and
most single output tube amps.

Ones that use direct transistor drive to the output tube cathodes *- *ie
Peavey Heritage series and most Music Man models.

But it is still a *VERY *bad idea to let musos chose and install their own
tubes.

I think the ALL amp making companies, Sony, Pioneer, Denon, Yamaha,
not just Fender or Marshal, like people to blow up as many amps as
possible.

However could they survive if things lasted for ****in ever?

The average person replaces his average amp about every 10 years or
less. The companies would really like to quicken the pace of
destruction. The companies employ arsoles whose job it is to excavate
quality, think up the lies of marketing, and think of new ways people
can spend their money without the slightest betterment to anyone
except the company.
Companies need suckers, and no attempt must ever be made to protect
them from mishaps which are always the fault of the sucker.

How often have you had transistor amps with blown transistors but the
fuses are intact?

Little boxes, Little boxes, clustered on the mantle piece and

All made out of ticky tacky and they all look just the same.

I have seen a few tube amps with cathode biasing which have still
sustained bias failure, or a tube just deciding to give up and turn
red for days until someone notices the smell.

In hi-fi amps where hardly any power is used the best protection is to
have cathode current monitoring and a shut down circuit which trips if
Ik rises more than twice the bias for longer than 4 seconds. This
means that if a speaker shorts or somebody allows cables to short
( which often happens and kills lotsa bjt amps ) because of poor
termonals and a failure to twist up wires nicely, and someone turns up
the volume into a short, the amp turns off rather than melt down.

There is not one single amplifier I have ever seen which has a
protection circuit that instantly guars against a short circuited
output. It would be so simple to do. One would have a couple of chips
which determine if the load value falls below 2 ohms. So the
protection circuit must sample output current through say a 0.1 ohm R
and compare it to a sample of the output voltage. If the voltage
across the 0.1 ohm current sensor is higher than a certain fraction of
output voltage then the load must be too low and the amp disconnects
its speakers and then turns itself off OFF.

Why do I have so many amps coming to my bench despite the so called
protection? Usually because low loads have been used for too long,
which might only be 1 second - bjt amps can fail just than quick,
faster than a fuse can blow. Tube amps die more slowly, so usually 4
seconds of a short circuit somewhere won't do much damage. But after
that if things continue it can get terribly expensive and stinky.

Patrick Turner.





.... *Phil

[DM]

On Jun 14, 8:26*am, Patrick Turner wrote:
On Jun 14, 2:22*pm, "Phil Allison" wrote:

"Ian Iveson"

Patrick Turner wrote :

Not one guitar amp
manufacturer has ever put a musician proof biasing scheme under the
chassis of their creation. Shame on Fender and Marshal.

***Surprising. Why not?

** Because *NOTHING can be made musician proof *!!!

Eg. When the spigot breaks off a 6L6, musos plug them in any way it goes.

Well indeed such optimistic problem solving can lead to a big bill or
smoke or both.

I have not got around to working out how many deadly positions there
are for a 6L6 when there is no guide spigot.

Often the fuse is the last thing to blow.

But some over current sensing here and there would save the day.

The biggest killer of output and power trannies is saturating tubes
before they melt down when the current overheats everything. But I
avoid this problem in all my tube amps I build with simple current
sensing on each cathode so that if one or more output cathodes pulls
more than twice the bias current for longer than 4 seconds the amp
turns off.

This might upset the musos at a gig when they drive the output stage
deep into class C.

But with 6L6 or 6550 the threshold can be 200mA and that should not be
a nuisance.

A guy once sent me two amps with a pair of 2A3 and kitted out with
potted Tango trannies. Both power tranny primaries went open after he
plugged in the 2A3 the wrong way because the dopey Chines makers of
the tube sockets did not make 2 holes for anode and grid small enough
to keep the larger pins for the cathode out. The guy just sat there
gazing and wondering why the power trannies got hot with no music -
and then they cooled down, and still no music.
There was cathode biasing which did not save the power trannies.
I have seen Quad-II amps have troubles when an ESL57 panel starts
arcing above some low level threshold which of course is way too low
for anyone's kids. The brats like turning it up, and up and up even
more.





It's a while since I've seen a new guitar amp, but I would have thought
some of them might have made an attempt by now.

** A number of tube guitar amps *DO have self *biassing.

Egs:

All the ones that use cathode resistor bias - *ie Vox AC30 and clones and
most single output tube amps.

Ones that use direct transistor drive to the output tube cathodes *- *ie
Peavey Heritage series and most Music Man models.

But it is still a *VERY *bad idea to let musos chose and install their own
tubes.

I think the ALL amp making companies, Sony, Pioneer, Denon, Yamaha,
not just Fender or Marshal, like people to blow up as many amps as
possible.

However could they survive if things lasted for ****in ever?

The average person replaces his average amp about every 10 years or
less. The companies would really like to quicken the pace of
destruction. The companies employ arsoles whose job it is to excavate
quality, think up the lies of marketing, and think of new ways people
can spend their money without the slightest betterment to anyone
except the company.
Companies need suckers, and no attempt must ever be made to protect
them from mishaps which are always the fault of the sucker.

How often have you had transistor amps with blown transistors but the
fuses are intact?

Little boxes, Little boxes, clustered on the mantle piece and

All made out of ticky tacky and they all look just the same.

I have seen a few tube amps with cathode biasing which have still
sustained bias failure, or a tube just deciding to give up and turn
red for days until someone notices the smell.

In hi-fi amps where hardly any power is used the best protection is to
have cathode current monitoring and a shut down circuit which trips if
Ik rises more than twice the bias for longer than 4 seconds. This
means that if a speaker shorts or somebody allows cables to short
( which often happens and kills lotsa bjt amps ) because of poor
termonals and a failure to twist up wires nicely, and someone turns up
the volume into a short, the amp turns off rather than melt down.

There is not one single amplifier I have ever seen which has a
protection circuit that instantly guars against a short circuited
output. It would be so simple to do. One would have a couple of chips
which determine if the load value falls below 2 ohms. So the
protection circuit must sample output current through say a 0.1 ohm R
and compare it to a sample of the output voltage. If the voltage
across the 0.1 ohm current sensor is higher than a certain fraction of
output voltage then the load must be too low and the amp disconnects
its speakers and then turns itself off OFF.

Why do I have so many amps coming to my bench despite the so called
protection? Usually because low loads have been used for too long,
which might only be 1 second - bjt amps can fail just than quick,
faster than a fuse can blow. Tube amps die more slowly, so usually 4
seconds of a short circuit somewhere won't do much damage. But after
that if things continue it can get terribly expensive and stinky.

Patrick Turner.



.... *Phil

My Musician BRAIN cannot handle all this information LOL.. Thanks for
all the help!

[Patrick Turner]

On Jun 15, 5:25*am, DM wrote:
On Jun 14, 8:26*am, Patrick Turner wrote:





On Jun 14, 2:22*pm, "Phil Allison" wrote:

"Ian Iveson"

Patrick Turner wrote :

Not one guitar amp
manufacturer has ever put a musician proof biasing scheme under the
chassis of their creation. Shame on Fender and Marshal.

***Surprising. Why not?

** Because *NOTHING can be made musician proof *!!!

Eg. When the spigot breaks off a 6L6, musos plug them in any way it goes.

Well indeed such optimistic problem solving can lead to a big bill or
smoke or both.

I have not got around to working out how many deadly positions there
are for a 6L6 when there is no guide spigot.

Often the fuse is the last thing to blow.

But some over current sensing here and there would save the day.

The biggest killer of output and power trannies is saturating tubes
before they melt down when the current overheats everything. But I
avoid this problem in all my tube amps I build with simple current
sensing on each cathode so that if one or more output cathodes pulls
more than twice the bias current for longer than 4 seconds the amp
turns off.

This might upset the musos at a gig when they drive the output stage
deep into class C.

But with 6L6 or 6550 the threshold can be 200mA and that should not be
a nuisance.

A guy once sent me two amps with a pair of 2A3 and kitted out with
potted Tango trannies. Both power tranny primaries went open after he
plugged in the 2A3 the wrong way because the dopey Chines makers of
the tube sockets did not make 2 holes for anode and grid small enough
to keep the larger pins for the cathode out. The guy just sat there
gazing and wondering why the power trannies got hot with no music -
and then they cooled down, and still no music.
There was cathode biasing which did not save the power trannies.
I have seen Quad-II amps have troubles when an ESL57 panel starts
arcing above some low level threshold which of course is way too low
for anyone's kids. The brats like turning it up, and up and up even
more.

It's a while since I've seen a new guitar amp, but I would have thought
some of them might have made an attempt by now.

** A number of tube guitar amps *DO have self *biassing.

Egs:

All the ones that use cathode resistor bias - *ie Vox AC30 and clones and
most single output tube amps.

Ones that use direct transistor drive to the output tube cathodes *- *ie
Peavey Heritage series and most Music Man models.

But it is still a *VERY *bad idea to let musos chose and install their own
tubes.

I think the ALL amp making companies, Sony, Pioneer, Denon, Yamaha,
not just Fender or Marshal, like people to blow up as many amps as
possible.

However could they survive if things lasted for ****in ever?

The average person replaces his average amp about every 10 years or
less. The companies would really like to quicken the pace of
destruction. The companies employ arsoles whose job it is to excavate
quality, think up the lies of marketing, and think of new ways people
can spend their money without the slightest betterment to anyone
except the company.
Companies need suckers, and no attempt must ever be made to protect
them from mishaps which are always the fault of the sucker.

How often have you had transistor amps with blown transistors but the
fuses are intact?

Little boxes, Little boxes, clustered on the mantle piece and

All made out of ticky tacky and they all look just the same.

I have seen a few tube amps with cathode biasing which have still
sustained bias failure, or a tube just deciding to give up and turn
red for days until someone notices the smell.

In hi-fi amps where hardly any power is used the best protection is to
have cathode current monitoring and a shut down circuit which trips if
Ik rises more than twice the bias for longer than 4 seconds. This
means that if a speaker shorts or somebody allows cables to short
( which often happens and kills lotsa bjt amps ) because of poor
termonals and a failure to twist up wires nicely, and someone turns up
the volume into a short, the amp turns off rather than melt down.

There is not one single amplifier I have ever seen which has a
protection circuit that instantly guars against a short circuited
output. It would be so simple to do. One would have a couple of chips
which determine if the load value falls below 2 ohms. So the
protection circuit must sample output current through say a 0.1 ohm R
and compare it to a sample of the output voltage. If the voltage
across the 0.1 ohm current sensor is higher than a certain fraction of
output voltage then the load must be too low and the amp disconnects
its speakers and then turns itself off OFF.

Why do I have so many amps coming to my bench despite the so called
protection? Usually because low loads have been used for too long,
which might only be 1 second - bjt amps can fail just than quick,
faster than a fuse can blow. Tube amps die more slowly, so usually 4
seconds of a short circuit somewhere won't do much damage. But after
that if things continue it can get terribly expensive and stinky.

Patrick Turner.

.... *Phil

My Musician BRAIN cannot handle all this information LOL.. Thanks for
all the help!- Hide quoted text -

- Show quoted text -

As I might say here, " Dozen Madder Duz it? "

But of course life's tranquility does matter and depend on a whole
range of things including the serenity of your vacuum tubes in their
sockets. Biasing needs to be right.

Patrick Turner.