# Traynor Bassnmate



## benthebeat (Nov 18, 2021)

Hello! Just joined the forum, looks good! My question is about a Traynor Bassmate amp
that I got from, beleive it or not, the garbage! It was pretty messed up so I brought it in the shop
and got it working after changing tubes and some caps. it is a model YBA-2 1966 version
with the 6AV6 pre amp tube. Sounds awesome and very loud! Maybe too loud?
I've checked a few schematics that show a 47K - 1W resistor in the power supply section 
but the amp I found has a 4.7K. Anyone would know if this could cause premature tube wear?
I tried a 51K instead and didn't notice any change in the output. Will check voltages and keep you
posted. Thanks!


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## Paul Running (Apr 12, 2020)

You might want to install screen stopper resistors for each 6V6, 470Ω is a typical value.


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## benthebeat (Nov 18, 2021)

Paul Running said:


> You might want to install screen stopper resistors for each 6V6, 470Ω is a typical value.


Ok so they would be in series with pin 4 of each tube right?


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## Paul Running (Apr 12, 2020)

Correct.


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## benthebeat (Nov 18, 2021)

Paul Running said:


> Correct.


Great! Thank you very much! Well appreciated.


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## traynor_garnet (Feb 22, 2006)

You found an early bassmate in the garbage??!! I want to move to your neighbourhood.

Does it have a tube rectifier?

TG


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## jb welder (Sep 14, 2010)

benthebeat said:


> I've checked a few schematics that show a 47K - 1W resistor in the power supply section
> but the amp I found has a 4.7K. Anyone would know if this could cause premature tube wear?
> I tried a 51K instead and didn't notice any change in the output. Will check voltages and keep you
> posted. Thanks!


The 47K there (in schematic you posted) is an error. It looks like the schematic has been re-drawn & cleaned up and they missed the decimal place.
If you do calculations from the voltages they give for points A and B, it is impossible with a 47K there. For the way it is shown, there would only be 1.5mA to power the screens and all the preamp tubes.
When you do your voltage measurements, you will find a much greater drop than 70V across that resistor if you have a 51K there.
As you say, it works, but I expect it will sound very saggy at any substantial volume. Probably a lot more dirty too.


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## Paul Running (Apr 12, 2020)

You should have lots of fun with that amp...a nice simple circuit.


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## benthebeat (Nov 18, 2021)

traynor_garnet said:


> You found an early bassmate in the garbage??!! I want to move to your neighbourhood.
> 
> Does it have a tube rectifier?
> 
> TG


Yep! 5Y3


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## benthebeat (Nov 18, 2021)

jb welder said:


> The 47K there (in schematic you posted) is an error. It looks like the schematic has been re-drawn & cleaned up and they missed the decimal place.
> If you do calculations from the voltages they give for points A and B, it is impossible with a 47K there. For the way it is shown, there would only be 1.5mA to power the screens and all the preamp tubes.
> When you do your voltage measurements, you will find a much greater drop than 70V across that resistor if you have a 51K there.
> As you say, it works, but I expect it will sound very saggy at any substantial volume. Probably a lot more dirty too.


I just played it for a while and yes, it's hard to get a clean sound at high volumes, will replace the 51K by a 4.7K
You guys are just great! Cheers!


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## benthebeat (Nov 18, 2021)

traynor_garnet said:


> You found an early bassmate in the garbage??!! I want to move to your neighbourhood.
> 
> Does it have a tube rectifier?
> 
> TG


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## benthebeat (Nov 18, 2021)

benthebeat said:


> View attachment 388387
> View attachment 388388


Gotta get a tube socket for that 6L6...used a 8 pin standard control relay socket for testing!


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## benthebeat (Nov 18, 2021)

Also used a 7025 instead of the 12AX7A, less noisy.


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## benthebeat (Nov 18, 2021)

The amp had been detached from the original bass cabinet and was in an old ply wood frame...I built a new plywood frame!
Still have to stain it and put a handle. The speaker cab I'm using is a Yorkville 2 X 10 inch. Celestion Red Back. Punchy!
Will try on my Mesa 2 X 12 see how it sounds.


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## Lincoln (Jun 2, 2008)

Paul Running said:


> You should have lots of fun with that amp...a nice simple circuit.


I really like the way it's drawn too.


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## benthebeat (Nov 18, 2021)

Paul Running said:


> Correct.


I added the 470 ohms and as shown on the drawing, also added the resistors in series with pins 4 but didn't have 1.5K's so used 1K's instead. The sound is indeed cleaner at higher volumes but I get a HUM which seems to be amplified compared to what it was before. I have that hum with nothing plugged to either inputs, now it seems louder even with the volume all the way to 0. I ran a solid bare copper wire awg 14 inside the amp along the sides, connected to chassis and I hooked up all grounds to it, that should not cause the hum..? I don't have a scope but will try with a multi-meter to measure the frequency of that hum. The meter has a Hz measuring function. Not sure if it's 60Hz.


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## jb welder (Sep 14, 2010)

benthebeat said:


> I ran a solid bare copper wire awg 14 inside the amp along the sides, connected to chassis and I hooked up all grounds to it, that should not cause the hum..?


Yes, it could. Any time you alter the grounding scheme you run the risk of introducing ground loops. Grounding can be very complicated.
Whenever you modify something and find a new issue, first suspect is your mods.


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## benthebeat (Nov 18, 2021)

jb welder said:


> Yes, it could. Any time you alter the grounding scheme you run the risk of introducing ground loops. Grounding can be very complicated.
> Whenever you modify something and find a new issue, first suspect is your mods.


Yeah, you're right, gonna re-wire the grounds back to the original placement. Thanks man!


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