Build Your Own Clone Message Board

Okay, so I can't believe this actually works.

I took the first two preamp stages (both triodes of V1) of the Univalve and mocked it up Runoff Groove style. As per the ROG method, each triode was replaced with a JFET with a drain trimmer.

IT WORKS!!!!

I will be adding on the second preamp tube's stages in the near future, just to complete the preamp circuit in pedal form. The complete circuit *should* be decently high gain.

What does it sound like? I very punchy, lightly overdriven boost that is hella-dynamic. You can pick normally or even a little heavy and get some clean, slightly trebly boost, but if you really dig in, it gets dirty. It sounded SICK with my Franken-Tele's bridge pickup. SICK!!!

Please note: This is a circuit snippet (a building block), for the most part. It does work on its own, but more development will likely yield a much better result. But it sounds pretty cool as is.

I used 2N5457 and J201, and both work fine in either position. The sweet spot for bias on these is tight, so be patient while trimming.

This layout is verified. I built the basic trace-shape on perfboard, using the layout graphic below as a guide (no schematic was used for this), so this PCB should be fine.




PCB layout (print at 166 dpi):




Here's the proto build:

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Function f(x)
TightCamera - Gear Reviews

Very cool, FJ. I can't wait to dig into this. One question: Am I seeing two +9v points or is that a misprint?

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Sweet. Just don't expect the next "great thing". It sounds good, but maybe not mind-blowing good. Like I said, I think this will be a useful building block. I'm just excited that it worked.


You are correct. I didn't want to run a jumper (being stubborn). I actually did jumper it on my perf board build.

Another note: the output volume is not loud. But I used a 100K "gain" pot (which is really just volume in this context). I think a 1M pot would be give more volume.

I think this project will really come together once both tube stages (4 gain stages in total) are put together. We'll see.

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Function f(x)
TightCamera - Gear Reviews

Very nice work man! I like what you've done here - do you have soundclips or are you waiting until more work is done?

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- Robert ...

This is very cool.

Do I understand correctly that you are basically taking what is in the Univalve and modding it to solid state while still maintaining the basic character of the amp? Having never played the univalve, is your initial foray promising in that regard (i.e. is your "very punchy, lightly overdriven boost that is hella-dynamic" circuit reflective of the univalve?)

I cannot wait to see where you take this one! You are doing some very funky cool things, FJ.

Congrats on your success!!!

1,2
red-blue

Edited to satisfy a couple of English majors and myself.

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fiancee:
"You make bad decisions before coffee."
me:
"I make bad decisions after rum. Perhaps drinking has nothing to do with it."

I'm not sure yet. I'll try to refine this snippet a little more first before proceeding with anything else.



I used the Univalve schematic to recreate the circuit around the first preamp tube. It's hard to say if it has the character of the UV, because it's impossible to run the amp with just one preamp tube. Also, a huge part of the UV sound is based around power-tube saturation, and that can't be done with transistors. Once I get the second preamp tube circuit added, I can do a more proper comparison.

I think this type of little circuit would be very well suited as a front-end for rnagoda's 2w mini-amp and similar projects.

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Function f(x)
TightCamera - Gear Reviews

I mancrush you.
I hate I ovelooked this one. I have the amp and love it.

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“Why sip from a tea cup, when you can drink from the river.”
--Steve Martin

Me too!

I still need to finish this one. Thanks for the kick in the pants.

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Function f(x)
TightCamera - Gear Reviews

Hmm, didn't you do a valve jr layout using fets a while ago?
This is your second amp to pedal thing then

I did the Valve Jr. earlier this year. The Univalve is from 2009. Check the date of the first post.

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Function f(x)
TightCamera - Gear Reviews

Worm hole time skipping, dammit

I love this one because it sounds great at living room television volume.

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“Why sip from a tea cup, when you can drink from the river.”
--Steve Martin

I did the same thing

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