The Amp Garage

Could you perhaps post a plc of waveforms on scope screen? Also what amplitude input signal are you using? Those generic triode gain stages will not clip all that softly. And yes, asymmetric clipping is typical. Maybe your expectations do not meet reality. Something like a Tube Screamer or Big Muff ...

shane wrote: ↑Tue Apr 05, 2022 5:09 pmI didn't know that Hafler or Crate had done it before do you have any idea which of their amps they put it in?

Well, at least T2 preamp (Hafler) and GT-80 (Crate).

Finally seeing the "OTS" circuit I must say I'm dissapointed. Eventually no different than what Hafler or Crate did more than 30 years ago and even in the 1970's there were far better "tube power amp" emulations built entirely with semiconductors. A single-ended common cathode amp stage with token t...

The only thing that doubling the output tubes is guaranteed to get you? Assuming the output tubes test the same ) is double the clean head room in the output stage. Only if it actually increases the output power. And without modifications to power supply it doesn't. And what's double clean headroom...

The less number of times that your guitars signal passes thru a coupling / tone cap the less phase changes will take place and the more natural the guitar will sound, two to three gain stages max which would include the PI section in PP type amps. People seem to have no issues with Soldanos, 5150's...

Do you know any cool mods that would make it usable? Hmmm... I see a very Fender-ish clean channel and an OD channel with a lot of influence from the revered 2203 with input boosted. Quite a lot of low cut there, but there usually is in "higher gain" amps... I know, I know, these MA-series amps do ...

Do note that PI coupling caps are reactive components and if inside feedback loop such will effect phase of the feedback signal. If you dimension them too low (corner frequency high enough within audio band) you start to introduce positive feedback at low frequencies and risk amplifier stability. Th...

It's a "bias cell". Basically a battery.

IMO, if you want the amp to reproduce the sound of the acoustic instrument without coloration it beats the purpose of using tubes. Acoustic amps generally need wider bandwidth than guitar amps (probably needs a HF speaker) and while little bit of distortion can be tolerable on an acoustic guitar it ...

It could be practically anything. There were hybrid amps long before the Valvestates even appeared. Probably not a Mesa though since, AFAIK, they never manufactured a -guitar- amp with solid-state output section.

The VTM series is basically a Marshall 2203 "clone" with some extra improvenents an the DIP switches introducing various typical modifications to the circuit (yes, one of them equivalent to that "Jose mod" with clipping diodes). I doubt rebuilding would make the amp any better, as it in practice is ...

I don't quite follow the logic... You dial volume pot to "0" and the wiper is essentially grounded and thus the signal path too. Both schemes do this; the usual method of volume pot wiring, and the schematic example's series resistor to a pot wired as variable resistor (which isn't overly different ...

3. I see nothing invalid in the scheme, although it differs from the most usual scheme of wiring pot as volume control. Yet, it's still a basic resistive divider: In one extreme the signal takeoff point is between 220k (series resistor) and 1M (least attenuation), in the other extreme between 220k a...

Then again, application counts too. Fat and fuzzy distortion is typical for stoner rock (and maybe doom) but one wouldn't possibly use such tone to hard rock or modern metal. Many Orange users may have also employed treble boosters and other outboard pedals. Stories seldom discuss that part.

As rough generalisation: Differential (PI) stage typically clips rather symmetrically and "soft" (low order odd harmonic distortion) while a common cathode stage (this would be the typical "driver" voltage amplifier stage for cathodyne PI) clips rather asymmetrically and "hard" (higher order odd and...