Tube Amp Archive

Wow, that Pacific TV site is a gold mine. Thanks for sharing. The 6GH8 sounds like a strong option -- I'll have to do a bit more design research and will be sure to come back with more questions!

Eirinn

Hey Jack, that's an interesting idea. Have you seen any schematics that use 6GH8A tubes? Curious how one would go about designing around the two stages. Is the triode stage similar in gain to an AY or AT stage? I suppose the other block for me is I'm up in Canada, and while those tubes are pretty ch...

Thinking about my next build – I found an old gutted record player cabinet and thought it might be fun to make a "living room" amp. It's got a hole cut for an 8" speaker, which I will proceed to rip out of a solid-state practice amp :wink: Been interested in the Micro designs on Robinette's page, wh...

I've had the build done for a month now but it's taken me that long to get this post written! Anyhow, I thought I'd drop a little update to let you all know that the amp is up and running and sounds excellent. I did end up swapping the input jack for a shorting jack (thanks maxkracht for the suggest...

Been occupied with other projects the last week, but I managed to get back into the 5E3 and make some changes the last few days. Long story short, the high-frequency oscillation is improved but not eradicated. Now that the going concern is no longer "low voltages," please let me know if it's better ...

Thanks for all the replies. I'm using Hammond iron (290AX + 1750E). The PT has two high voltage taps, 550-0-550 and 650-0-650 The 290AX is 275-0-275 or 325-0-325. Copy that, sluckey -- forgot to halve the voltages per side. Got my wires crossed so to speak! 750 ohms seems pretty big there. How did y...

Just fired up my new build – I'm a bit puzzled by my voltage readings and was hoping some of you fine folks could point me in the right direction. Here's the schematic: royale_5e3_v1-1.pdf I'm using Hammond iron (290AX + 1750E). The PT has two high voltage taps, 550-0-550 and 650-0-650. Because I'm ...

Thanks for the recommendations. I've read Merlin's book on preamp design — there's a lot of heady information there and I haven't quite absorbed it all yet. But I am getting a handle on common-cathode gain stages, load lines, and biasing. Reading about sluckey's builds now!

Well, it turns out that putting the circuit back together was the answer! I hooked up the reverb and tremolo portions, and the weird volume-drop issue is gone. The overdrive is also much smoother. Starts to growl at around 4 on the dial. Overall the amp sounds great! Something I noticed while puttin...

Listened to your sounds clips, are you rolling the volume up & down or is that what the amp is doing on it's own? That's what the amp is doing on its own. As the volume and bass are turned up, the effect is more pronounced. Is this what is called "parasitic oscillation"? I've heard the term but am ...

This is what I saw, not sure how you have it at the moment. Yep, that's it. I moved that coupling cap directly to the grid because the long lead was causing oscillation, but neglected to get the arrangement right with the 1 meg resistor directly below the cap. I've since replaced that resistor and ...

Oh, here are the new voltages on V4A:

6: 231
7: 25
8: 71

Higher than the schematic, but right now everything is 20-40 volts higher.

If it were mine I would re-build it. Brad over at Brad's guitar garage has done a number of full re-builds of these style amps. Given the mods and lots of questionable soldering areas, this just might be fun to take it back to stock. Get rid of the spaghetti wire, put in cloth, refresh caps, check ...

[/quote] The PI triode V4A is either bad or wired wrong. See schematic for pin voltages. The coupling cap that is presently going to pin 7 of V4 (right at the tube socket) is in the wrong position. It has been moved (physically & electrically) so it looks like you are feeding B+ from the previous st...

Hi all, this is my first post on ampgarage, though I've been lurking and reading as much as I can over the last year or so. My experience: I've built one tube amp, the 18 watt Superlite TMB. I started with the Mojotone 18 watt kit and adjusted the circuit with additional components etc. Amp works li...