• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Nutube and TPA3116 hybrid (cheap fun little Amp)... Help please

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Puggie

Member
Joined 2004
Hi all.

I've begun to put together what I intend to be a cheap little amp to sound nice (more pleasing than absolutely accurate). So I already had the cheap red pcb TPA3116 board and it's pretty impressive for what it is IMHO.

Now I've bought and assembled one of Pete Millet's Nutube buffer boards to use as a front end. Problem is one side biases up fine the other sits around 20ishV, also the VFD teal blue section is much brighter for one side than the other. Any suggestions on where to start trouble shooting?

The boards are running off a shared 24v power supply, nothing in the amp looks wrong, the faulty channel measures slightly higher voltage here and there, and I see no reason for this, could I have a faulty nutube? Any ideas other than spin in rough draft in the PCB and see if the fault stays with the board or follows the tube chip?

Thanks.
 
PRR

PRR

Member
Joined 2003
Paid Member
Post your voltages, bad and good. While you have your nose close, re-re-check all resistors and joints.

A bad tube is always possible. However it would be a drag for you and Pete to do an exchange, and it turns out not to be the tube, but something "easy".
 
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