Tube Amp Archive

Perhaps a slightly different perspective? If designing an amp from the ground up, after the basic hardware parameters are sketched out in pencil (tubes, power supply, output transformer primary), much of the fundamental “personality” of the amp can be distilled through more detailed design of the po...

Thanks for checking the little fella out. Your comments are very kind. I had originally tried to figure out how to continuously vary all the power tube voltages, bias, and OT impedance proportionately with a single control, but realized I just wasn’t smart enough to make it happen. Has anybody got a...

Few months ago I built a small dual-EF80 powered push-pull class AB practice amp (<1.5W). Using it, turns out it’s still loud enough to annoy “she who must be obeyed” sleeping in bedroom adjacent to den, (although not annoying with practice during the day). So I thought it would be fun to design a s...

May I suggest these additions (if not already elsewhere, apologies if they are):

https://dalmura.com.au/projects/Valve%20Info.html

And a wonderful treatise on hum:

https://dalmura.com.au/static/Hum%20article.pdf

Copy. Thank you!

Would it be inappropriate here to ask your process(es) for quantitatively measuring a transformer and inferring (I.e non-invasively) construction/quality of components?

Hi Bergheim, Right on. Yeah, I guess there’s different scales of loudness, right? 100W - everyone leaves. 50W - drummer says you’re too loud. 20W - singer says you’re too loud. 10W - singer says you’re still too loud. 5W - singer still says you’re too loud. < 1.4W - with the door to the den closed, ...

I just finished the little table-top cabinet for this little fella. I made some minor adjustments based on how the speaker and cabinet sounded. All in all pleased that this didn't sound nearly as tiny and boxy as I thought it could. Thanks Amp Garage community for all the inspiration. https://youtu....

Hello Martin, Here's a PDF from KiCAD (My first time - please forgive rookie effort). I appreciate your gentle prodding to get "with the program". EF80 Mini Practice Amp schematic.pdf and here is the KiCAD .sch file (zipped) EF80 Mini Practice Amp.kicad_sch.zip If anyone has any interest in actually...

Thank you for the tips Martin. Zipping everything together! Brilliant.

I’m guilty of modifying my Spice libraries to the point where I can’t keep track of what is “standard” and what’s not.

Glenn, Martin, Per Martin’s nifty suggestion, I’ve attached a PDF screenshot of my Spice schematic with all the visual noise removed – comments, voltage measurements, op data labels, yadda yadda. I’ve moved all the notes from my Spice file into a separate document. If the PDF is unreadable, I can ma...

Hi Glenn, Absolutely - Let me work on it. I'm not hip much cool-guy schematic software but I'll come up with something for you in pdf. I ended up making my own EF80 pentode model for simulation, so that is included as well as my little potentiometer model (which strangely didn't exist in my regular ...

I just finished a small practice amp project with a speaker defeat and headphone jack. It took a couple of weekends, was a fun project, and pretty much does what I had hoped it would do – nice cleans with decent harmonic overtones and good sustain, goes up to moderately distorted output cranked, has...

RyanThomas13,

Replied to your PM - sorry I haven't been on in a bit. Modeled your amp in LTSpice, have a few thoughts. Please let me know if my reply and attachments received, if not I can try to post on this thread.

GrayDigger

Thanks Mike. Yes, I guess most of the time it’s loud enough even with our drummer :lol: I’m always amazed at the depth of knowledge and wisdom so freely shared by members on this forum. So grateful for the opportunity to spend the wee hours (OK, too many of them) exploring a seemingly endless stream...