# Traynor ycv50 blue bias problem?



## Rob P (May 24, 2016)

Hey guys!
Just got a used Blue (got another thread in the amps forum). 

Clean channel sounds good, but the drive channel had virtually no low end.

Also, it seems to be eating preamp tubes early.

Questions:
1. Is it normal for the Blue to have not much bass response?
2. Is there something that would cause preamp tubes too fail quickly?
3. Anyone know where the bias pot is? Or if there even is one?

Thx!!!


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## Adcandour (Apr 21, 2013)

I thought they were self-biasing (or something to that effect)? I used to own one ages ago and remember that being the case.


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## GTmaker (Apr 24, 2006)

none of the problems you described sound normal to me...
I would have the amp checked out by an expert and get the problem solved.

G.


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## jb welder (Sep 14, 2010)

Not sure about the amount of bass that is normal. If your local L&M is convenient, stop in and try another to compare.
There should be an internal trim pot for the bias. The 'auto' circuit is for matching.
How many preamp tubes went bad? Modern tubes are a crapshoot. They can be bad out of the box or go bad real quick. If it's a one-off, I wouldn't worry.


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## Rob P (May 24, 2016)

Tgan


jb welder said:


> Not sure about the amount of bass that is normal. If your local L&M is convenient, stop in and try another to compare.
> There should be an internal trim pot for the bias. The 'auto' circuit is for matching.
> How many preamp tubes went bad? Modern tubes are a crapshoot. They can be bad out of the box or go bad real quick. If it's a one-off, I wouldn't worry.


Thanks!
The tone was a bit bland when I bought it, so replaced them all and it sounded a bit better.. Then one of them died suddenly (after very little use).

The clean sounds on par with the ones at L&m. I should have spent time on the OD channel :dummy:

Does anyone know where that bias pot is? I was trying to eyeball it but didn't see anything obvious


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## Chito (Feb 17, 2006)

There is no bias pot in the YCV50. It is self-biasing. I've had one for years and just replaced tubes without having to worry about the bias.


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## dtsaudio (Apr 15, 2009)

Jb says there is a bias pot, Chito says no. Is there more than one version of the YCV50? My service manual shows a bias trim pot on the board that the output tube mount on. It's labelled P12 and is aprox in the middle of the output tubes and mosfet transistors


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## Rob P (May 24, 2016)

dtsaudio said:


> Jb says there is a bias pot, Chito says no. Is there more than one version of the YCV50? My service manual shows a bias trim pot on the board that the output tube mount on. It's labelled P12 and is aprox in the middle of the output tubes and mosfet transistors
> 
> View attachment 21265


Thanks! I'll see if I can find a pot there.


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## JerS (Jun 16, 2014)

I believe there was more than one version of this amp. If I recall, there was a service notice issued against the "self biasing" early versions. Though, none of the issues mentioned above sound like they would relate to amp bias (particularly if the clean channel is working as it should). The pre-amp tube failure could be an infant mortality issue with the tube. It happens. Seems that I see it a lot with EHX tubes (which are commonly sold through L&M).


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