The Amp Garage

One more thing I forgot: we are used to the sound of the PI with a 220k load. If you are looking for some "known" sounds, having a variable load between 600k and 1 MOhm won't sound the same. You have too much signal going to the ECC99, I'd attenuate it before hitting the PI. Are you sure you used th...

You built a 4 stage lead like Soldano, Bogner, etc.. Well, being the first stage in parallel, it's more like a VHT or Rivera. If you want to have that amount of bypassed stages, you need to drastically cut lows and highs on every stage. Coupling caps must be below 1 nF and you need snubbers as well....

I’d put 470p across the plate resistor of the second gain stage. Then you can further trim highs by using a presence pot like the Mesa Dual Rectifier does, on the EQ.

I agree. I’ve learned from Mike Soldano experience with a certain lot of SP77, and from Orange amps around 2010 to use 1 W resistor on plates (this applies as well on CF cathodes).

Some of them was failing because of this exact reason.

IIRC it considers a different standard.
EG if you drop the resistor in liquid nitrogen, you can declare it 100W

So ‘shade’ is referring to the coupling between LTP and output anodes? It is usually called Shade, but the "inventor" is Otto H. Schade (see attached 1941 patent), and is basically shunt applied feedback from anode to g1, so that means you need more current to drive the tube with the same swing. Th...

i'm also spending life in hotels and asking myself questions until when will be like this=? :P In my case, until work and know-how wont be in the same place. Then... 1. to go only with few electrolytics usually lead to instability and oscillations via power supply The final part of the amp is simil...

How does the PI work without the 2nd grid being AC grounded with a cap? Is that an omission, or do I need some learnin'? :) The latter. :) Both grids are referred to gnd because in this design, as explained, the ccs helps to recover the missing swing on the high voltages (because of the high value ...

IMHO part of the LTP sound IS the way it works with feedback: when overdriving, the sound will continuously flip flops between feedback controlled and uncontrolled scenarios in the same waveform, and this is part of that specific sound.

Tobyk wrote: ↑Sun Sep 11, 2022 8:41 pm Btw, you didn’t answer why you don’t like paraphase inverters

I can be biased by the fact that most overdriven sounds come from LTP based amps and the way it behaves, but I prefer the way the LTP sounds.

If you want to see a new phase splitter (I've never seen any like that before), take a look at the schematic below. It's an Hi Fi PP amp I'm developing (born as SE where I can get 26 Wrms at 5% THD with one single KT88) fully DC coupled. You can see the cascoded CCS as the tail, the balancing trimme...

Going on with methods to unbalance other PIs, with concertina you can simply set the working point of the previous DC coupled stage on the warmer or colder side, and change the behaviour of the concertina. You can also set a specific working point and then dc couple the concertina with a split load ...

I absolutely agree that the best solution is to experiment with different circuits and then see what we prefer. Yes, you can unbalance every PI you want in different ways. The hard task would be to keep it always symmetrical. What I like to use is a simple CCS as tail of the LTP, because you can DC ...

Hello, I report here a project that I have sketched these evenings in the hotel, to be developed in the coming months. A simple amp for clean, pedal-eating sounds, clearly to be refined in detail once built. It has only two power supply capacitors, one for the preamp and one for the PI and power amp...

Replacing the voltage divider on a paraphase with a pot would be easy enough, I believe. Seems noone here tried it though. Which is why I need to do it – I think I saw a thread on 18watts.com where Merlin stated disbalanced paraphases creates more 2H than LTP or Cathodyne. I tried, but I don't like...