The Amp Garage

Just don't use those cheap Tiwan switches, I had two of them break in the last week. It seems they have a weakness in the design such that pressure directly on the front of the toggle breaks them.

As far as the switch goes, I believe a simple on off switch is sufficient. The amp is a practice amp, and as such won't be setting around for protracted periods between sets where a standby position is useful. As long as the caps are rated for the initial voltage surge before the tubes heat up, ther...

The brown or black Bakelite ones work almost as well as the ceramic ones. I saw a lot of both in NAVY equipment years ago. I guess it depends on which type of plastic is used in the insulator as to how well they will hold up. Try melting one and see.

Class A 360degree conduction
Class B 180 Degree conduction
Class C less than 180 degree conduction (Not used for audio for the most part).

Class AB in between class A and Class B. Conduction of each tube less than 360 degrees and greater than 180 degrees.

Top and bottom without cab.

No such thing as modern vs classical class A. Class A is Class A. It means the tube remains in conduction 100% of the time. Class AB1 is class A at low levels, and class B at high output levels. Class B indicates the tube is in cutoff part of the time. So, class B is less than 100%conduction time. A...

Amp assembly is complete and I'm tweaking it as I've got a nasty 36KHz oscillation that shows up occasionally. It looks like it is in the first stage and is dependent on volume control setting (loading sensitive?). I pushed the 6P1Ps into AB1 and have an honest 10W out at the onset of clipping. If I...

375 no load, ie no tubes in place. I'm pushing the 6P1P to see what it will handle. Screens are now up to 250V with -16V fixed bias on the grids and B+ is down to 346V with 25mA and 27mA on the two output tubes with just them in place. B+ may drop another volt or two when the preamp tubes are instal...

The brown blob on the right is a super secret current source that I won't discuss as it is a super secret FET with a bipolar driver. (See Firefly SET amp at DIY for details). I was going to use a LED for the cathode bias, but I can't figure out how to bypass one with a cap to get the proper frequenc...

I hope everyone has a better year to come.

Steven

I built a champ like amp with a 6P1P output with selectable feedback, and selectable tone stack that uses a Hammond chassis (H1444-18, $14.35 @ Antique Electronic Supply) if you don't mind the size. I put it in an oak head like a Trainwreck. Thread is here: http://ampgarage.com/forum/viewtopic.php?t...

You can still buy waxed nylon lace specifically designed for this purpose. I have both white and black. If you want to know the technique, look for military procedures for lacing wiring.

I learned it in the NAVY in the early 70s and still use it today to bundle HT wiring, but not much else.

This is Victoria. Got the planed slats back and started the next build. I got the Hammond transformers in and am going to go for fixed bias at 375V B+ this time to see if I can get above 12W out. Unloaded the B+ is 385V and the bias is adjustable from -5 to -17V. I think I need to tweak it to a rang...

I've used an Allied 6K49VG which is built by Hammond and only runs $23.21 in single quantity. B+ is 460CT at 50ma which is will give near 325V if SS rectified. OPT for a low cost solution is limited to single impedance output but the Edcor XSE10-8-4K is a nice 8 ohm output with 4K primary and rated ...

Gun restrictions work as well as drug restrictions in the USA.

Oh wait, drug laws don't work either.

Never mind.