"abu" an amp for father's day

[thetragichero]

haven't built anything in almost a year for personal reasons but here we go

my dad asked me to keep an eye out for a small tube amp. with father's day coming up and an organ pull chassis that was sent to me sitting on the porch i decided I'd build him one instead. the idea was replacing the deluxe reverb he played throughout high school that we sold a few years back. basically building a princeton reverb without the reverb or wiggle, but slightly higher preamp voltage to match the deluxe reverb

tiny tiny chassis so chaotic point-to-point it is



transformer is lower voltage than I'd like (it's 280-0-280) so I'm going with a 5v4 rectifier i had lying around still in box for less voltage drop (i could've gone solid state but maybe the tube rectifier contributes to the sound). no choke, didn't have a metal oxide 1k like the princeton so it's 820r between plate and screen node. got most of it built yesterday besides finishing the ht and ground schemes, bias circuit, and a few other odds and ends (can't put in the control panel or tone stack stuff until i get the faceplate from my trophy shop guy). I'm thinking 10" speaker as long as i have one that's 4 ohms

[reTrEaD]

May 22, 2024 14:18:58 GMT -5 thetragichero said:

chaotic point-to-point

I've seen worse. Those little turret boards look nice. Where'd you get those?

[thetragichero]

antique electronic supply/ce dist of you have an account. yes they are pretty nifty

edit: www.tubesandmore.com/products/turret-strip-socket-mount-gold-plated-copper-single-row

[thetragichero]

starting to look like an amp



tolex on, grill cloth on (i cannot understate how much i abhor putting tolex on)

i didn't take any pictures of building the box because i didn't bring my phone into the garage. i used advantech sunfloor offcuts because that's what i had. since it's water resistant and nonporous i had to use loctite pl premium max and screws instead of wood glue and dowels. not a big fan of using screws

picking up faceplate today so o can finish building the chassis, test everything out, and put it all together over the next two weeks

[thetragichero]

my trophy shop guy does good work, even if he does fly the flag of a convicted grifter

[thetragichero]

whelp I've made an expensive and time-consuming paperweight. went to test that my calculations for the bias circuit were correct and somewhere between testing the transformer to obtain the secondary voltages and building an entire amp the power transformer primary is shorted. i just don't have it in me to try to fit a different power transformer in there

i won't delete this thread because maybe somebody can learn to test everything as you go along instead of trusting that it'll all work

[thetragichero]

after much cussing and gnashing of teeth and wanting to sell all my stuff i ripped the power transformer out of my dukane pa amp conversion i never finished and put it in there. better bias circuit (accounts for the wiper potentially going open). i think everything is done besides putting tubes in and testing out

[thetragichero]

today was install tubes and hook up to dummy load to bias. my initial plan was to use a 5v4 rectifier but the replacement power transformer is a little spicier so i tried a 5u4 (i have a TON of these from organs, seems like they all run em) but ended up using a 5y3 to get the b+ down (not trying to go fender here and push the limit of my 6v6) to a hair under 400v

after biasing i hooked up to the 4x12 on my work area and... sounds great! through such s big cab it was loud enough to vibrate stuff on my table. should be a bit more manageable

[thetragichero]

done. there are things i would do differently (made the panel made with more overlap or waited until i received the panel to route out where it goes) but it looks decent and sounds great. maybe a little bigger and louder than he'd like but it'll work

[frets]

It’s a beautiful color.

[unreg]

thetragichero, I’m sure your dad loved it! It’s beautiful and you, his son, made it. Too loud volume knob adjust. + It will sound great bc it’s an Arafel! You do create excellent products! Which reminds me, I should hook up your pedal again, now that my guitar is pretty much problem free.

[reTrEaD]

Jun 10, 2024 20:50:44 GMT -5 thetragichero said:

i tried a 5u4 (i have a TON of these from organs, seems like they all run em)

Very common in television receivers, as well. Higher PiV and maximum current than a 5Y3 and lower plate resistance, but not nearly as good as a GZ34.

Jun 15, 2024 8:41:02 GMT -5 thetragichero said:

there are things i would do differently (made the panel made with more overlap or waited until i received the panel to route out where it goes) but it looks decent and sounds great. maybe a little bigger and louder than he'd like but it'll work

Yeah, the route for the panel and the gaps at the corner protectors take away from the overall look, but it's still attractive. What size speaker?

[thetragichero]

10" organ pull alnico, forget which manufacturer