Tube Amp Archive

I've been through it and nothing is vibrating I think. Is it possible that the speaker I'm using can't handle a Class A power amp? I pulled it out of an old sansui hifi speaker. If the quiescent current running through the voice coil is non-zero, then the centerpoint of the mechanical vibration will...

morcey2 wrote:...awesome stuff...

Amazing... this is exactly the summary i was looking for.

Thanks!!!

-Jordan

With the help of this forum, I put together my record player guitar amp! I ended up ditching all the old components except for: 1) The switched 750k knob 2) The output transformer 3) The power tube (there was only 1) I think it sounds awesome (esp for $25), but there is a weird buzz when I'm playing...

I was initially under the impression that output (i.e. impedance matching) transformers were spec'd for actual impedance, but after some research it looks like impedance matching is purely a function of turns ratio and power handling. If thats the case, then a ~1000:1 turns ratio transformer should ...

I've got a bunch of 6AK5 pentodes, and I think I can't use them as mini-push/pull stages because the plate impedance is too high.

Can someone confirm this is true?

I went with a 80VA P115V/230V, S115V/230V ... I got 5 of them used on eBay for $75 shipped. EDIT #2 - the example grid voltage is -7.5v, so you're going to need a decent amount of gain from that op amp. I think you'll want a gain of at least 50 from the op amp for clean, and more if you want to over...

Is there any harm in making it a full wave rectifier instead of 1/2 wave? It just gives me better regulation but no voltage increase, right?

What if I add a single ended op-amp in a can-type package so I can still point-to-point wire it? What would get me past the input level problem.

Besides that, does the transformer I picked out look ok? Is there a cheaper option around?

Guitar pickups have lower output than a phonograph cartridge? The idea was to drop in an isolator, a 1N4007 for 1/2 wave rectification, and leave everything else as-is (except the caps). I can reuse the chassis, mounting, output transformer + speaker (theyre riveted together). Oh and I have 3 of the...

If this is the free pspice and you're using their diode models - they have a low breakdown voltage (50v or 100v or something). So you have to use a few in series. Genius. Now both the output transformer node and the plate node show ~83V DC. I guess the output transformer needs more juice and less r...

I have an old record player with a 1 tube amp. I put a photo of the schematic that is (helpfully) on the bottom of the case. It uses straight 120V from the wall for the DC power supply, which seems dangerous. I'd like to put an isolation transformer in there, but I have a few questions. I modeled th...