Switchable PI, Paraphase,Cathodyne, LTP.

[SemperFi]

Originally Posted by Printer2

But if tube amps did not have any sound why not just use transistors?

Because when transistors glow there is NO sound.

[SemperFi]

Very cool P2. I doubt u get much difference except when overdriving the PI, (at least when adjustnig for equal gain). But still a cool concept. Please keep informing us about what u think about the various PIs.

[Printer2]

Originally Posted by SemperFi

Very cool P2. I doubt u get much difference except when overdriving the PI, (at least when adjustnig for equal gain). But still a cool concept. Please keep informing us about what u think about the various PIs.

Yes in my world the PI will probably get overdrivem, or at least the following stage which will then drag down the signal of the PI. I did a slightly simpler circuit a while back with Paraphase, Cathodyne and one LTP combination.Somehow I misplaced a connection and ended up a pole short on the 4 pole switch and the LTP did not work. What did work was the Cathodyne and the Paraphase. I did not spend too much time playing with it but I found the Paraphase to sound fuller when mildly overdriven. It impressed me enough that I decided I would work out a way to simply switch between PI types (using two different switches or more poles would have been easier). I wanted to walk the line between simplicity in operation and variability. I also wanted to use circuit parameters that repeated results of classic circuits.

This is only one of a few ideas I will be throwing together in one amp to increase its versatility and yet limit the amount of gain stages. Too easy to just throw in more tubes.

[smoking-amp]

Maybe you could put interchangeable modules on perfboards with banana plugs. Then make each stage of the amplifier changeable on a chassis with banana jacks on top. You'll have to make the various modules somewhat compatible on gain per stage.

[tubelab.com]

Speaking of, where is that damn dog?

Still chasing the cat............

This is an offshoot from the $100 build, just doing it for kicks and to answer some questions.

I remember seeing a few variations of your multi - PI in that thread. I am still tinkering with my amps from that thread, and have a few more, but I haven't posted into that thread since Mister Killjoy had a fit over the cost of knobs. He also got real irritated at my use of sand, so one of my amps now has a mosfet split load PI. It works pretty good too.

In my case the mechanics and the cabinet building are always the hardest part but I just lucked into a good head start in that department.

Some friends and I were at a hamfest where one of my friends bought a Marshall 4 X 12 cabinet for $100. It contained Celestions too. The vendor had a bunch of dead guitar amps and it seemed that nobody was interested in them so he sold them all to me for $5 each. There are two cheap Fenders, a Crate, a Line 6 stereo head, and a no name reverb box from Japan. All solid state. I had planned to gut them and build tube amps in the cases, but the Fender G-DEC JR got my curiosity up, so I fixed it.

Maybe you could put interchangeable modules on perfboards with banana plugs. Then make each stage of the amplifier changeable on a chassis with banana jacks on top.

No banana jacks, but no soldering required just screw terminals. 80 Watt screen drive amp shown.

[smoking-amp]

Reminds me of a Christmas present I got from my parents waayy -- way back. It had just individual electronic components on plug in yellow plastic carriers with spring wire terminals or pins or something. Wish it had had tube input stages, phase inverters and output stages with OTs back then. I might have actually learned something in grade school then. But it was all solid state low voltage stuff to be safe.

[Printer2]

Originally Posted by smoking-amp

Maybe you could put interchangeable modules on perfboards with banana plugs. Then make each stage of the amplifier changeable on a chassis with banana jacks on top. You'll have to make the various modules somewhat compatible on gain per stage.

Thought about something like that to play around with. But in the end I want all the choices in the amp to be selected by a switch anyway so I think I will go in that direction.

[Printer2]

Originally Posted by tubelab.com

Still chasing the cat............

Yeah, but don't they realize it is dinner time?

I remember seeing a few variations of your multi - PI in that thread. I am still tinkering with my amps from that thread, and have a few more, but I haven't posted into that thread since Mister Killjoy had a fit over the cost of knobs. He also got real irritated at my use of sand, so one of my amps now has a mosfet split load PI. It works pretty good too.

I had one version that was to use a mosfet as a PI but never got around to trying it. Glad to hear it works, I may just give it a go for an amp I want to build for my nephew.

In my case the mechanics and the cabinet building are always the hardest part but I just lucked into a good head start in that department.

Some friends and I were at a hamfest where one of my friends bought a Marshall 4 X 12 cabinet for $100. It contained Celestions too. The vendor had a bunch of dead guitar amps and it seemed that nobody was interested in them so he sold them all to me for $5 each. There are two cheap Fenders, a Crate, a Line 6 stereo head, and a no name reverb box from Japan. All solid state. I had planned to gut them and build tube amps in the cases, but the Fender G-DEC JR got my curiosity up, so I fixed it.



No banana jacks, but no soldering required just screw terminals. 80 Watt screen drive amp shown.

I can do some rough metalwork at work, the cabinets are my sticking point especially since it is usually below freezing outside and I have yet to replace the motor on my table saw. Come summer I will catch up on that end.

I like the screw terminals but I have not scrounged enough to do what you have. I am trying to keep this hobby in check as I should be learning to play also.