The Amp Garage

You guys are way off the mark as to how Ken tested the OTs. The story I heard from Gregg Levy is that Ken had 'a guy' who did the testing. By holding the various OTs in his hands and making the call. Not kidding. He was a local guy, a neighbor of sorts (who's name was never given to me), and someone...

I'll be your first customer. A stock PR is a good circuit as is, and exactly what I'm looking for. Let me know when you have it done. Thank you!

Anybody installed a HT fuse in an Express? I'm haven't. Did Ken? Was this science beyond his scope? As to the shot noise of the 68K grid stopper pair (34K/136K) in a Fender amp, whether adding shot noise 4X greater than a 12AX7 or not (which I doubt in the guitar amp application), I would have to as...

Change the plate resistors, use 100K 1W CF, metal film here is a waste of time. The 470 ohm screen resistors actually benefit the sonics of the amp by using wire wound resistors. 5W ceramic block types are what I've always used in Fender builds. The carbon 3W parts that Fender used because they were...

Looking at that schematic, ignoring the sonic circuit side of it, the power supply AC connection could actually electrocute you. You see this right? The AC hot wire (Black) should go through the fuse and then the switch and then connect to the primary, the return AC path (White) should be a solid co...

A lot less, yep. And I say this because from my experience it's the filament winding that actually causes vibrational buzzing in a PT, and heat. And a 7-10A tap? It takes BIG WIRE inside those bell covers to do that. I mean seriously, have you ever seen a 35W amp with a bigger PT? It's way overkill ...

I'm saddened to hear this - and it's so late in the year that I'm finding this out! Patrick was one of those guys. His attention to detail and sharing personality made him unique in the music business. And actually, he was in the 'making' music business, even while working at a company making transf...

Here's maybe some odd input. A long, long time ago I ran into (and purchased) an original Fender 'Woody' amp, circa 1948 (I was told). It had the etched K & F Thunderbolt logo on the black metal chassis control panel. It had a silver 10" Jensen alnico speaker with the output transformer attached to ...

Yep, I've seen this in a Mesa amp, too. But as I recall, the wire went to a different tube? Maybe reverb circuit or maybe your recollection is better than mine. In fact, it might have gone as far as the output section? But it was a long wire in the amp I saw, not something that attached to the first...

OK, what I want to know is who came up with the idea (and solution) to add the coil of wire? The guy's certainly a genius, we need him to join the forum and start solving some amp problems....

Ah, it didn’t look like a Fender ‘OEM’ schematic so I ignored it. Sorry, Ten Over. I see so many ‘non-OEM’ produced schematics these days that I just instinctively question their accuracy.

I have to disagree with Stevem here. Given the same circuit, as the feedback ratio increases, say from 5:1 to 20:1 (‘59 Tweed Bassman - 5:1, to JCM800 - 20:1) the amp has more gain and is looser (as Stevem states) but the higher ratio will also have MORE treble (along with more bass), not less. Reme...

The schematic posted is missing a .0047 cap on the Bass Channel as I recall? I’m not near a schematic but I believe it was a treble roll-off bridging cap that existed between the volume pot and treble pot. This needs to be removed for guitar work, be advised. As to replacing the stock electrolytic c...

Hey Phil. I have considered this idea. But I'm thinking something that works for a cathode resistance change on V1 may not fly so well here. I have to think it would basically create a super high resistance that would simply turn the NFB off, much like a 250K pot on a BF Fender would do. Funny thing...

A revisit... So, I opted for a 3-way switch, and for the reason that I could accurately hit my targets. However, I have come to appreciate the adjustable potentiometer usage - but only for the reason that it doesn't make a 'POP' sound at the speaker when making NFB adjustments. Yep, it is always in ...