This thread had me curious about how the old PP EL84 Silvertone console amp I rebuilt would perform on the QA tester. Not great, but not horrible.
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Darnnit you guys!!! I wish I didn’t… but I started digging through my boxes of tubes and output transformers today. Looks like a strong possibility I’ll be designing and building a 15 wpc EL84 push-pull amp this winter. I pretty much have everything except the power transformer 
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That sounds like a fun project!!
If I do decide to build it I’ll start a new thread with all my design details and more pictures than anyone wants to see…
Toroidal?
Soo.. Because reasons.. I’ve got some 6AQ5 tubes. And me being a complete moron about this stuff I’m wondering if these transformers could work:
The 6BQ5 that they say those output transformers are for appears to be a pentode also and kinda similar power output in SE to 6AQ5. Thats about as far as I can stretch my knowledge right now lol.
No clue what 1st stage I should use. I’ve got a spare 6n2, but no idea if that would be compatible. I’m so ignorant of the minutia of tube circuits still I probably shouldn’t even be asking these questions.
Don’t know anything about this design, but here’s a thread about an SE 6AQ5. If you want to build it, let me know. I’m pretty sure I have a few NOS 6AU6 in my stash.
Looks like 6BQ5 operates at higher voltage than the 6AQ5 so no go on those specific transformers. Found some schematics for both using 12AX7 1st stages:
Eric is shiping me that Antek toroid power transformer. With the tubes and output transformers I have this should be a totally awesome 10 wpc amp! New thread will be started when I get going on this amp build.
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-I moved the 470k resistor (far left) a bit farther away from the 5watt one. Figured it would keep things a bit more balanced L/R so a resistor on one side doesn’t get alot warmer than the other.
-I ended up getting some real alps pots since they were under $8. Installed it. The shaft hole needed enlarging, and I had to drill a new turnstop/indexing pin hole farther away (90deg from the original).
-Installed the .47uf PIO caps from Tom_S. Higher value than the originals (oah no more bass 
) but they sure are chonkers!
The new knob I installed (now smooth shaft instead of splined) has number markings 1-12. If it starts at 1 and turns to stop at the same spot.. it stops at 11. So it goes to 11 now 
Patiently waiting for a moment to test it 
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Thanks for the heads up Drew!!! I somehow missed those Alps pots on clearance.
Don’t forget the “FINAL20” promo code that gets another 20% off it since it is sale/clearance. The 50kohm Alps pots become $6.29ea
I just put 2 in my cart.
Thanks Drew!!
Yep, me too!
OK I got it hooked up for a few songs in between movies tonight.
Sofar (on the 4ohm taps) the changes seem to make this amp less “in your face” with the holographic tubiness. The soundstage widens even more, bass lifted to be more equal and connected, and the presentation softens to allow the music to be the main focus again. Seems to be a more refined presentation. Less something to “wow” me for 30 min until I turn it off. And more something to be drawn into for an entire evening. Everything is a give and take, but this is probably a step in the right direction.
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