Tube Amp Archive

I see, you want to run both loop sends into a mixer, without changing anything upstream and then feed the return into one of the PI inputs. Maybe a pot could be wired as a balance control with the wiper feeding the C-lator’s buffer input? This is hanging more stuff off the signal paths, but would b...

Might need to experiment with the mixing resistor values to balance the channel volumes.

Thought: If building into an external box, potmeters instead of (or in addition to) resistors could act as individual channel volumes..?

double post...

Should be able to reroute a few things and or lift some component leads to test it. The inside of the Matchless is notoriously difficult to experiment with. There are no turret boards, and the soldering is very difficult to desolder and unwind. I once installed a VVR in my previous DC30 in 2009 and...

For the LTP to work properly, the ring of one of the TRS plugs would need grounding. Or just use a mono TS plug for one, TRS for the other. Good suggestion, that makes sense: Use a TRS on one of the loops (ex Ch1) for send and receive, and a TS on the other for send only that connects with the tip ...

Do you realise that the 250k send loop level control in Dumble type loops makes the preceding send buffer somewhat pointless? I'm not saying they don't produce super awesome toanz, just that they aren't an example of a transparent fx loop, because the send impedance won't be low (and may be rather ...

I'd be reluctant to modify this amp, but I think I would try some small reversible modifications to see if mixing the two channels can be made to work satisfactorily. Something like this: Yes, I would not do any modding of this amp. It's a Sampson era all-original so it does have some collectors va...

I came across the Trinity TC-15 schematic, which is a 15 W clone of the DC30 with a common FX loop and added reverb that gave me an idea. Note that there is one error in this schematic: There is a node at R12, R13, R14 and R15, not jump. TC15 kopi.gif Concept: I want to use a single FX processor for...

Greetings! Once again I have another project: I've been missing my Matchless DC30 that I sold in 2009, regretting it ever since. Now I just received a 1994 SC30. One of the curiosities of this amp is the separate FX loop inserts for each channel, each returning into opposite sides of the PI. So usin...

Best youtube-video I've seen in a long time!

Just tried lifting the resistor and cap leads and run a wire to the speaker ground as you suggested. That actually made the hum worse; back to more or less the same level as when the OD section of the preamp ground was connected to the speaker/OT ground. Not sure why that would be, maybe some other...

you should beleive only to yourself not to some random grounding methods from the internet.. i never use any of the proposed gnd methods because they are often way out from optimum or full of mistakes. ha, now question how to do that? you are on the good way i see already.. and one day when you wil...

There is one part of the above experiment that won’t be optimum, and that is the phase inverter ground, at the junction of the 390 ohm resistor and 2.2 uF cap. That belongs to the power amp, and should be grounded where the OT secondary common is grounded. The short under-board jumper tying that ey...

I think you can try this as an experiment. Disconnect the wire at the red X, and add a jumper on the main board as shown by the red arch. This seems to be the least invasive way to test the theory. Once you do that, you can try different locations to ground the OT common. The location shown in the ...

Ok, will separate and ground the OD trim pot where you suggested.

But what are the "shields"?
And should I leave the bias ground where it is, or move to filter ground?