The Amp Garage

Hey All, I am continuing to tweak on my 100W ODS-101-HRM. I have played the amp for about a year and am 90% happy with it. I have pulled it out of the cabinet and looked at my biasing. It is running 49V and 50mA. This seems a bit high to me put the trimmer pot is at the extreme of it's rotation. I h...

Tonegeek,

You are certainly correct. I was looking at a schematic by Odourboy dated Jan 2008. It shows B+1 BEFORE the standby switch. I guess I should re-title this post 'Location of B+1'.

Thanks to everyone.

To All,

I'll weigh in with my own drawing. So my real question is.... Standby switch before B+1 or between B+1 and B+2. Advantages or disadvantages to each.

I've drawn the choke only version


Cheers, Mike

Nicht,

That's what I was looking for ... a reason to do it or not. Arcing does not concern me, current does.

Cheers, Mike

Hey All, I am again digging into my ODS-101 HRM to make a few tweaks. In researching the schematics I see some in which the standby switch is directly after the bias board (before B+1) and others in which it is between B+1 and B+2. In this case, since the OP center tap is on B+1 it will be getting p...

Hey All,

I am leaning towards trying a 1.5k grid stopper on the 6L6's. Another thought, the amp originally used 6V6's. I have NOS 6L6's in it now could this casue the fizz????

Cheers, Mike

To All,

In another forum someone suggested grid stoppers (1.5k). Tubes are good, no microphonics. I might just try the resistors.

Cheers, Mike

To All,

In another forum someone suggest grid stoppers (1.5k). Tubes are good, no microphonics. I might just try the resistors.

Cheers, Mike

Yes - that would be a 6G6B circuit.

Hey All, I have a '63 Bassman. I have recently noticed that if I strike a note it rings clear, then as the note beings to fade a noticeable fizz appears. It is not a sub-harmonic or Intermod. In fact it seems to be either a fundamental or a higher-order harmonic of the note. It persists even when th...

Hey All, I have recently acquired a '63 Bassman with a 6G6B circuit. The amp is 90% original but for a couple of mods. One that I am wondering about is that there are 1.5k Resistors hanging off of pin 5 of the power tubes. I think these are called grid resistors. They are not original to the circuit...

Hey All,

Someone on the forum had the boards for sale. Does anyone remember who that was?

Cheers, Mike

Hey All,

Has anyone ever done a drawing of pre circuit board Fender schematics and layouts? I get frustrated trying to read the poor quality scans that are available.

Cheers, Mike

Hey All,

Is there any way to tighten the receptacle pins in the tube sockets? I have a couple of sockets with pins so loose that if weren't for the retainer they would fall right out! This can't be good.

Cheers, Mike

Hey All, I just picked up a '66 Bassman. I opened it up to look at the circuit and found that the bias had already been changed over, so far so good. Then I started looking into the feedback loop. This has been modified as well. There is the 820 Ohm resistor except it is not connected to the OT it i...