Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Jalmeida on February 23, 2023, 01:45:22 pm

Title: AC15 w/ Reverb Updates
Post by: Jalmeida on February 23, 2023, 01:45:22 pm
I am working on this project in sporadic bursts as time permits and to break up other projects. I have a majority of components and wiring with the excpetion of the reverb wiring. Then have been working on a cabinet. Anyway, here are some pictures.
Title: Re: AC15 w/ Reverb Updates
Post by: Jalmeida on February 23, 2023, 01:46:48 pm
A few more
Title: Re: AC15 w/ Reverb Updates
Post by: ac427v on February 23, 2023, 04:57:16 pm
Beautiful cabinet. Almost a shame to put a covering over that woodwork!
Title: Re: AC15 w/ Reverb Updates
Post by: Jalmeida on February 23, 2023, 06:54:33 pm
Beautiful cabinet. Almost a shame to put a covering over that woodwork!

Thanks so much. This was my first project with fingerjoints. It took a bit of fussing to get the fit right on some scraps. And this amp had one joint go a little wonky due to my fixture shifting. I corrected it for function knowing it would be covered. My next one I want to make is a 1x12 mahogany cabinet for my AC4TV. The 8” speaker is incredibly boxy sounding, but otherwise a great little amp. Those joints will be better and visible.
Title: Re: AC15 w/ Reverb Updates
Post by: Jalmeida on March 24, 2023, 11:24:15 am
I got this hard to find vox JMI era Fawn repro tolex in. I got the tolex on and piping trim in the slots. This JMI style fawn tolex couldn’t be more different than the current fawn stuff. I am currently in a holding pattern waiting for grill cloth and gold T-trim.

 Also I finally received my power transformer and got that installed. Also wired up the disconnect that will be where the reverb circuit sub chassis ties in. There is a jumper plug for the time being that will be the initial power-on debugging setup. Then once I get the stock circuit sorted I will breadboard together a test circuit and play with mixing resistors and different cap value until I get the reverb working how I want it. Then I will build that into the sub-chassis for installation. I am
Excited to be playing with the circuit outside of the amp beforehand. I think that will make it less likely that I mess up wiring to fix/modify and experimental circuit.
Title: Re: AC15 w/ Reverb Updates
Post by: Jalmeida on March 24, 2023, 11:28:01 am
And
Title: Re: AC15 w/ Reverb Updates
Post by: Jalmeida on March 24, 2023, 11:29:51 am
A few more
Title: Re: AC15 w/ Reverb Updates
Post by: Bieworm on March 24, 2023, 03:07:44 pm
Nice job man👍👍👍
Title: Re: AC15 w/ Reverb Updates
Post by: Jalmeida on April 30, 2023, 08:46:59 am
Got the custom JMI spec Output transformer and choke installed and wired. Soon will be power on checks and then tubes. Amp is currently without reverb and the round connector is the future reverb interface. Currently it is jumpered to make it stock AC15 configuration. I am admittedly concerned with the cable lengths. So that may change.
Title: Re: AC15 w/ Reverb Updates
Post by: sluckey on April 30, 2023, 11:21:50 am
Wow! Looks like the real deal.    :thumbsup:
Title: Re: AC15 w/ Reverb Updates
Post by: Jalmeida on April 30, 2023, 01:48:20 pm
I forgot to also mention, if anyone is looking for accurate AC15 Output transformers and chokes, talk to Soursounds in Portland. Bryan is great to work with an meticulous. The lamination layup and winding configurations on the original JMI Output transformer are both unique. And while you can get close on some off the shelf, these are spot on in all the specs. And the choke DCR on the original chokes are not off the shelf available either.