Newcomb AV-10 -All tube record player used as guitar amp [schematic]

[caspercody]

Hello

My brother in law got his hands on a Newcomb AV-10 all tube record player, and he loves the way it sounds playing his guitar through it. He says the distortion is awesome. I attached a copy of the schematic.

Would a buffer before the amp be used?
Is the distortion from this from the power tube (EL34)?
Do you see any improvements needed to this amp to work with a guitar?

Thanks
Rob

[ppluis0]

Do you see any improvements needed to this amp to work with a guitar?

Hi caspercody,

Try to remove the feedback resistor (18K) that connects the output transformer secondary to pin 2 of the 6AV6 tube.
This way you obtain a slight increase in gain, reduce the damping factor and have increased the distortion.
It's preferebly to lift one end of this resistor and test the amp to hear if you like the mod.
If the sound is worse without feedback connect this resistor again and try to buffer externally the guitar signal.
This way you reach to overdrive also the preamp tube.

I found this link that can be of your interest: https://www.tdpri.com/threads/the-newco ... mp.809176/

Cheers,
Jose

[modman]

Nice project, one one preamp stage away from being a Champ... so why not feed it a simple booster, or even overdrive used as clean boost (gain dialed down). The bass and volume controls are in the front of the amp, so they function exactly like what your guitar already does. No doubt you will be winning gain by cutting that out... The treble control is connected AFTER the preamp stage (blue)... In order to really get a feel of what this amp can do, I would bypass all tone controls...

If you look at the input, it even says - input from amp... probably because there used to be some preamp to amplify the signal from the record player?
But what is that connection at the volume control:

connection.png (101.18 KiB) Viewed 6065 times

You could also use diodes for rectification, and recuperate the socket for another preamp tube...

[gght]

Pot similar to this??

https://www.tedweber.com/wp354at

[ppluis0]

Pot similar to this??

https://www.tedweber.com/wp354at

Exactly !!
Once upon a time were common that pots with a fixed taper were used to implement a frequency compensation as function of the loudness level

Cheers,
Jose

[gght]

Pot similar to this??

https://www.tedweber.com/wp354at

Exactly !!
Once upon a time were common that pots with a fixed taper were used to implement a frequency compensation as function of the loudness level

Cheers,
Jose

Funny. I had seen on a schematic maybe ten or fifteen years ago. Don’t know why I remembered. Them I googled “tapped potentiometer “. There it was.