Traynor YCV40 master volume mods

[bagolies51]

I am looking to mod my Traynor YCV40 amp. I have searched high and low to try and find specific instructions on how to make the presence control a MV similar to the YCV50. Apparently Traynor used to tell people how to do it but stopped because of warranty issues. Any help would be greatly appreciated

[Tage]

you should be able to figure it out from this, if you can't get it figured, maybe you should have someone else be doig it...

http://www.traynoramps.com/downloads...an/smycv40.pdf

[bagolies51]

you should be able to figure it out from this, if you can't get it figured, maybe you should have someone else be doig it...

http://www.traynoramps.com/downloads...an/smycv40.pdf

I have the service manuals for both amps and have compared the two. There are several differences between the amps and I'm not sure which ones pertain to the MV/presence control. I have modded several effects pedals, built one from a kit and also built a kit amp. So I am not totally new to this but would like to do things myself because I would not learn anything by just giving it to someone else to do.

[Tage]

I get that feel. I'm gonna go over it and get back to you.

[Tage]

SO it took me a while to get around to this but I finaly had another look. If you make the connections that are outlined in the M613 section rather than the connections in the m581, the 20k presence control will be changed to a master volume control, wich normaly would be too small a value, but it is driven by the low output impedance of an opamp so it should work fine. although it is either Master volume or presence not both.

So to do this you would remove jumpers x24, x34, x41 and install jumpers x65 and x66 and then add r51 which is a 1.5k resistor. The other resistors should be left, as the feedback signal does not need to be changed.

I hope that makes sense, and all those jumpers printed on your PCB

Good Luck and be safe, Tage

[bagolies51]

Tage,
Thank you for taking the time to look into this. Yes, it all makes sense to me now. I'll be glad to finally get rid of the useless presence control on this amp.

[Tage]

Happy to help, they are good amps, but I'd have to agree with you that it's nicer to have a MV

[bobloblaws]

SO it took me a while to get around to this but I finaly had another look. If you make the connections that are outlined in the M613 section rather than the connections in the m581, the 20k presence control will be changed to a master volume control, wich normaly would be too small a value, but it is driven by the low output impedance of an opamp so it should work fine. although it is either Master volume or presence not both.

So to do this you would remove jumpers x24, x34, x41 and install jumpers x65 and x66 and then add r51 which is a 1.5k resistor. The other resistors should be left, as the feedback signal does not need to be changed.

I hope that makes sense, and all those jumpers printed on your PCB

Good Luck and be safe, Tage

This thread dates back to 2012 but I hope I can resurrect it.

I'm attempting this mod and I'm wondering why you say the NFB loop does not need to be addressed when there are clearly differences in the two designs. Also, should not the output of the reverb circuit be rerouted to pin 2 of U1?

I'm attaching the schematics I'm using to suss out this mod.

sm_ycv40_2015.pdf

sm_ycv40_M581-7.10.pdf

[Enzo]

Look at the YCV40, the NFB is a 220k/4k7 divider into the PU. Now look at the YCV40/50 drawing, it gives the exact same circuit for the 40 version, and a slightly different feedback resistor over the same 4k7 for the 50.

[bobloblaws]

Look at the YCV40, the NFB is a 220k/4k7 divider into the PU. Now look at the YCV40/50 drawing, it gives the exact same circuit for the 40 version, and a slightly different feedback resistor over the same 4k7 for the 50.

On the 50 version in the 40/50 drawing I see the 270K feedback resistor in series with C58 and R76 in parallel. Are you saying C58 and R76 are of no consequence in this circumstance?

[Enzo]

I am saying they are of minor consequence. it is a little tone tweak they did for the two models based on the circuit. In any case you were working on the MV, which is a different circuit.

[bobloblaws]

I am saying they are of minor consequence. it is a little tone tweak they did for the two models based on the circuit. In any case you were working on the MV, which is a different circuit.

OK, thanks for the help. I hadn't realized that the 4K7 resistor was NFB related, you learn something new everyday as they say.

I have the mod prototyped at the moment and it is working but with a caveat. If I hit a big chord hard (with humbucker guitar at least) there is some nasty distortion happening. I wanted to rule out the possibility that the NFB was a factor.
I think the first thing I'll do is put it back to stock to double check there wasn't already an issue to begin with.

Thanks again.

Oh, by the way, what does "PU" stand for? I assume it is the presence control pot you are referring to.

[Helmholtz]

On the 50 version in the 40/50 drawing I see the 270K feedback resistor in series with C58 and R76 in parallel.

Not related to the MV subject, but while the audible difference between the two NFB networks should be minor, the additional lead compensation (C58//R76) in the 50 may be essential for ensuring HF stability.

[Enzo]

Where is "PU"? I see P10 as the presence control. P for potentiometer.

[bobloblaws]

Where is "PU"? I see P10 as the presence control. P for potentiometer.

In msg #9 you wrote "Look at the YCV40, the NFB is a 220k/4k7 divider into the PU"