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Show us your flea-watts amps!

jobrewer1983 said:
Well I can tell you they are not china made tubes :)

I’m cool with the blue, it’s the red I dislike lol
Click to expand...
Oh, I didn't mean only Chinese-made tubes. Russian, US, and European output tubes can glow, too. :thumbsup:


blue_tube_glow_Bandmaster_Reverb.jpg

Blue glow off Russian 6L6GC tubes.
 
Redd House said:
Absolutely no noise whatesoever fully cranked save for a barely detectable trace of hum. Not sure where that's coming from.
Click to expand...
Very good! Ever measure the mVAC riding on top of the B+ of the power supply?

You need less than 10mVAC to have a silent background (using headphones at full volume to monitor). Tubes have a higher shot noise which is impossible to eliminate.
 
Mr Boochie said:
Very good! Ever measure the mVAC riding on top of the B+ of the power supply?

You need less than 10mVAC to have a silent background (using headphones at full volume to monitor). Tubes have a higher shot noise which is impossible to eliminate.
Click to expand...
No, never tried that. But the same hum is there whether the knob is on 0 or if it's on 11. :p
My best guess is it's the tubes but like I said it's barely detectable so I never tried to track it down.
Otherwise, dead silent. :)
 
Redd House said:
No, never tried that. But the same hum is there whether the knob is on 0 or if it's on 11. :p
My best guess is it's the tubes but like I said it's barely detectable so I never tried to track it down.
Otherwise, dead silent. :)
Click to expand...
Sounds good! Indeed, there is a lot of filtering for a headphone amp. :thumbsup:
 
Mr Boochie said:
Sounds good! Indeed, there is a lot of filtering for a headphone amp. :thumbsup:
Click to expand...

I used to have it hooked up to full size 3-way Technics bass reflex floor speakers and a Wollensak 8075 as a dedicated 8-track cart system. 2 watts is pretty damn loud. I'd typically crank it up 3/4. Now it's just one of my two headphone amps. :bigok:
 
McMack said:
What are your thoughts on the Oldchen?
Click to expand...

I was enjoying it until in an effort to figure out what the trim pots underneath are for I messed up the hum balance.

300B tube amplifier bias question (with a picture :-)

I have an Oldchen 300B amplifier here and I'm trying to figure out what the trim pots do. HiFi-Exquis was kind enough to send me an owner's manual, but the function still isn't 100% clear to me so I just asked for a schematic this morning. "·The device has two internal adjustment 300B electron...
audiokarma.org

Have not hooked it up with the bottom off yet to try to quiet it down. It is still usable I suppose, but I have other amplifiers and a diy speaker project I'm working on.

Edit 4/18/2025: forgot about this post until now, shortly after I made this post I was able to reduce the hum using the trim pots and then I ended up selling the amplifier to a friend.
I think about buying it back a few times a week. :biggrin:
 
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