Tight Squeeze - Tiny Tube Amp

SerpentRuss

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This is all incredibly cool. Anyway to hear how it sounds?!

Yes, I'll get my son working on that. He's only been playing about 14 months, so you'll have to give him a bit of a break on content. ;) It's easy to get a direct recording via the headphone jack. A mic might be a bit harder since we're running the whole house fan these days and the ambient noise in the house is pretty outrageous.
 

afterdarkmusic

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Yes, I'll get my son working on that. He's only been playing about 14 months, so you'll have to give him a bit of a break on content. ;) It's easy to get a direct recording via the headphone jack. A mic might be a bit harder since we're running the whole house fan these days and the ambient noise in the house is pretty outrageous.

A direct sound makes sense since its intention was to be used for headphones! I'll just put my headphones in and pretend I'm playin ;)
 

NSB_Chris

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I think I'm right about lowering the center-tap resistors as well, because I tested before and after. Electrically, think about them now being another heater element in parallel with the other two, since the two 68K resistors connect to each other via ground. The ground reference just "un-floats" the AC in reference to ground.
Correct but if you went from 470 ohm to 68k as you stated, then you increased the resistance, not decreased. With the 470 ohm resistors you would have pulled about 7mA and with the 68k resistors you would have pulled much lower ~0.05mA. I don't think either would have had any noticeable affect on the voltage from the transformer, so if that had any affect, then I wonder what it was.

Valve Wizard notes that low valued resistors are used on artificial center taps to reduce leakage currents: http://www.valvewizard.co.uk/heater.html
Not sure exactly what affect "leakage currents" would have.
 

SerpentRuss

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Correct but if you went from 470 ohm to 68k as you stated, then you increased the resistance, not decreased. With the 470 ohm resistors you would have pulled about 7mA and with the 68k resistors you would have pulled much lower ~0.05mA. I don't think either would have had any noticeable affect on the voltage from the transformer, so if that had any affect, then I wonder what it was.

Valve Wizard notes that low valued resistors are used on artificial center taps to reduce leakage currents: http://www.valvewizard.co.uk/heater.html
Not sure exactly what affect "leakage currents" would have.
Crap, I went from 470 to 68, not 68K. Sorry for the typo! I just went spelunking in my box o resistors and picked a pair of one watts that were a lot lower.
 

SerpentRuss

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OK, A little housekeeping. I am putting up a new, as-built schematic both a photo and a .pdf file. I'm also still trying to get an audio recording of this little amp from my son. I guess I have to post a link to youtube or something like that when he finally records something?

TightSqueeze.JPG
 

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  • TightSqueeze.pdf
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SerpentRuss

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A direct sound makes sense since its intention was to be used for headphones! I'll just put my headphones in and pretend I'm playin ;)
Here is a short audio file I finally pried out of my son. Recorded direct, focus rite line inputs from the stereo (mono signal) headphone jack. Two tracks: American Strat neck pickup for rhythm, Epiphone Casino (P90) solo thing at the end. Totally raw, no cabinet or mic syms, no noise reduction.

https://jmp.sh/zGvpD2C
 




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