The Amp Garage

Bit of a necro-bump, but I've used EVA-based glue for surround coating, specifically Helmar Super-Tac thinned with water. It's white, but dries clear after the water fully evaporates. I dried a puddle of some and it forms a silicone-like rubber. I've been thinning it in hopes that it'll penetrate th...

Does the ext. cab. out already have a switching jack? They did some wacky stuff at the end of the Silverface era.

Removing cathode bypass caps in the preamp will make the amp less gain-y but won't change the ultimate output.

I posted in your other thread, but for anyone else interested in significantly reducing the power in one of these late Silverfaces with the center-tapped bridge rectifier, look at the "1/4 power" switch on the "red knob" Twin schematic. 6V6s not necessary.

It's not a 7199 but I have a ton of 6GH8s lying around. I could donate a couple if martin is willing/interested in checking out a triode/pentode preamp tube.

Is it a Challenger CHB-10A? If so, the schematic can be found here: http://makearadio.com/schematics/images/bogen-chb10a-4.jpg Or other Bogen schematics here: http://makearadio.com/schematics/ The preamp is weird, at least for guitar world. Grid-leak biased first stage, fixed-bias second stage... th...

It will have zero tonal effects, because it's impossible for it to have any tonal effects. Unless, of course, you were using a power cable that's far too thin to begin with, but then the benefit mostly lies in not burning your house down every time you go to practice. Compare your amp's power cable ...

Start with increasing the cathode resistor, unless your OT's primary impedance still works with the lowered screen voltage. High plate voltages require higher values of cathode resistor, which leads to pushing the bias even colder when plate current increases, leading to more crossover distortion. T...

In case it isn't obvious, Antek rates all their PTs for their total current draw, so subtract the VA you need for your heaters and then you'll see what it can deliver for your B+. Then again, they're also rated for 50 Hz, so you can squeeze a little more current out of them at 60 Hz. I did a similar...

IIRC the stamped steel baskets were the ones that are prone to failure. Like this: [img:1024:768]http://i38.tinypic.com/1z4x3kw.jpg[/img] They made a run of 15s with this basket construction and those REALLY had problems holding the magnet without deforming. I have one of these 15s and knock on wood...

On a 2x6v6 amp, I would have thought a 150mA choke would be enough. I also assumed you would want more inductance--say 10H, or so. Disclaimer: I freely admit that I may know only enough to be dangerous--so to speak. Both good points. I'm biased towards overdesigning - look at the max. instantaneous...

I think you'll want more current handling than that for a choke that's going to filter all the B+ for the amp. If you look at some old Sunn (or just Dynaco) schematics, you'll see chokes in parallel to increase the total power handling, which would be all well and good if you could guarantee the cho...

Bill Fitzmaurice is still cranking out horn designs.
http://www.billfitzmaurice.com/index.html

It looks like he's made some transmission line-esque projects too:
http://www.billfitzmaurice.com/TLAH.html

If cost is a concern, I just used a Musical Power Supplies OT40PP for a quad of cathode-biased 6V6s. I really like it, but haven't tried it side-by-side with other OTs. It's rated at 45VA, 40Hz - 15kHz. 29M6 laminations, USA made. No idea who's actually doing the winding, but this guy really seems t...

Usually the problem with getting something insane out of resonance is damping. This is pretty straight-up physics stuff. It's how ported speaker cabinets work . Nothing strange or unknowable about it, just lots of stupid math. I remember in one physics lab in college we did an experiment with a litt...

Well, kind of. When I built a rocket-y amp, I used the extra triode for a single gain stage "normal channel". One gain stage, to volume control, to phase inverter. It still breaks up, of course, but quite later on its volume knob than the rocket channel. If you're looking for zero breakup from the p...