The Amp Garage

I have always been curious as to why MR D continued to put this FET input on the amps if it is so useless. If the amps are 'tailored to the client' and the clients put tape over the FET input, why keep including it in the amp design?? So perhaps, 1) I have not seen enough pictures (are there ODS amp...

Better for achieving what? Have you read the descriptions of #124 and the attempts to recreate it? I would recommend the 101 schem - but pick either HRM or Non-HRM, they're a little easier to read. I am still figuring all this out, but I thought I read that #124 was a good sounding amp (some post b...

HiGain did an amazing job on these schematics. Agree; I have noticed how the tidbits of expert info can be spread out over hundreds of posts. Its great to have all the good ideas in a single schematic. On a more pragmatic level, which is better starting strategy: A)Start project as Final ODS-101 or...

Seems you could also just disconnect input signal from the grids of a pair of tubes, leaving them idling. Then the impedance doesn't change. I thought about that but I think the impedance will still mismatch in that situation. Like if you were doing mechanical work with 4 human arms on a lever. If ...

Your schematic looks correct. The two resistors in the circuit are 10K. When the switch is placed in the half power position, the two tubes still conduct a little current (about 2ma) and the LED will have a soft warm glow :). Thanks for the info on the resistors; I was imagining frying a lot of LED...

When you "lift" 2 tubes don't forget your speaker impedance changes to a smaller number . i.e. run an 8 ohm speaker on the 4 ohm tap. Ideally your switch could incorporate the impedance change. You barely notice the difference in power so a better solution might be to: a: lower the PI voltage at th...

Some others:

BM = BluesMaster
PI= Phase inverter
100k Amp = 100k plate resistors in use
OD = overdrive channel
124 = Dumble #124 = de-gooped amp, reasonably well interrogated.

Assuming you have a positive voltage on the LED, I would think the top 2 terminals on each side of the switch in your drawing should be reversed. That way the LED is grounded when the switch is in half power, turning it on. My self-taught opinion.... Sorry the diagram is not real clear but a tiny "...

I searched and could not find this, so this is my guess on how it is wired. I'm just a guitarist, so the EE's will have to help me out on this one to know if it is correct. Here is a repost of the picture of the back of the switch (#124) and my guess at how it might work. Why do I care? Just trying ...

Thank you for the suggestions.

Just curious as to any suggestions on how to deal with unused wires on an output transformer. The reason I am asking is that in making a ODS clone with just a single 4 ohm output I may wind up using a OT with an 'extra' 8 ohm tap. If I don't want to implement a 'ohm switching' setup, what should I d...

Fischerman wrote:
Input jack is up at the top left it's just not shown. The 22K grid stopper and 1M ground reference are shown. Standard input jack stuff.

I was curious about the "FET" input, or is that essentially useless for solidbody guitars?

First off, thanks for posting these schematics, they are 'enjoyable reading.' :) First, for the 3 schematics, am I correct that the one "ODS-101" contains all the info for both HRM and NON-HRM? Is that why there are 3 schematics? Second, where is the input jack? Is there another schematic for this p...