Hot Rod Deluxe Conversion to ?

[dujuarez]

I have a 40 watt Hot Rod Deluxe that I would like to convert to a ab763 single channel. What I would like to know is can I still use my transformers and speaker?

[EL34]

Sure, you can re-use transformers and speakers

[dujuarez]

Great! I choose to use the AB763 because I love the sound of my Blackface Twin Reverb. Now I'm thinking that it's possible to use one of the other Hoffman amplifier models.  But what about the transformers requirements for the other models. For example, the champ probably is using a transformer with less power than the AB763. Would I have to change the component value if I were to use my transformer with say the Hoffman AC30? Or I'm I wrong about my thinking.


Thanks for you help.




David

[EL34]

The amp circuit board does not care what transformers or speakers it gets hooked up to


The power tube impedances will dictate what output tranny you should use
AB763 power tubes should not be a problem


AC30 is a whole different set of transformers for how a AC30 power section operates

[HotBluePlates]

If you want to reuse the transformers and speaker you have, and have a 40w donor amp, you should look at a 40w AB763 circuit.

Candidates would be the Super Reverb, Vibroverb, Pro Reverb, etc. Mostly, these models differ in the size and number of speakers (although there are sometimes subtle changes of power supply voltages or negative feedback amount).

The power supply will likely take some adapting, if for no other reason than the stock power transformer requires a bridge rectifier (which no AB763 amp used), and supply voltages may be higher than many AB763 amps (which you might choose to reduce somewhat via power supply decoupling/dropping resistors)

[drew]

Perhaps consider a Tweed-era circuit since you already have a Blackface amp?

http://www.tjadamowicz.com/amps/convert.html

[EL34]

I am working with Larry Rodgers right now on some fixes for a Blues Junior


The separate tube board is a POS
Thin traces, thin board, too much heat


Not sure if your amp suffers from the same bad design?

[dujuarez]

I like what tjadamowicz did with his Hot Rod Deluxe. Does anyone know if he has or sells schematic and layout design to accomplish tweed transformation? Or can I take any tweed amp design that is close to 40 watts? Yeah, my amp has giving me so much problems through the years. I bought it when it first came out. It was much of a problem play at home till I started using it for gigging.

[dujuarez]

If I were to rework my Hot Rod Deluxe and try and build the AC30 with new transformers, would I have to use two speakers like the original design? Is there a method of using one speaker maybe similar to AC15?

[Bautista392]

I also want to convert my Hot Rod Deluxe but instead to a late '60s vibroluxe reverb using the same valves and transformers but I'm not entirely sure if I can reuse the twin 6l6s and tri ecc83's and was wondering what would be best to just replace the main board and recycle most of the parts on it

[tubenit]

I would use a Hoffman board for the AB763.  I'd only use the transformers and tubes. Perhaps IEC socket.

Turret Board Order page (hoffmanamps.com)

I would not use any component on the PCB board and I'd have all new caps and resistors for that.  I personally would not reuse the filter caps on the B+ rail and I'd get new ones.  I'd get new tube sockets. 

I converted a Fender SuperSonic that was not working into a Carolina Overdrive Special for a friend. However, I built my own board. It also involved moving the location of tubes and plating over open holes from previous tubes.

Just an example of one way it can be approached.  There are others also.  My friend is very happy with the amp and it's his #1 now.

With respect, Tubenit

[AlNewman]

There are ways to modify the hot rod to be more like an earlier circuit, or even tread into marshall territory.

I left mine basically stock on the clean channel, and heavily modified the drive and more drive channels, which were basically a hot mess before.  The drive channels now are really nice with a lot of options.  There's a lot you can do with the switching relays, coupling, and bypass capacitors to add and cut frequencies, but you also have to dump voltage so the amp works properly.  I'm looking over the schematic again, and perhaps I could redesign the phase inverter for a 12at7 vs a 12ax7, but for now it works fine.

I have found that some of these boards are easier to work on than others.  I've worked on a couple where the terminal holes were so small that the solder couldn't be removed.  There was one where every ribbon cable broke by the time i had rotated it up and down a few times.  You don't want to have to resolder every ribbon cable, especially on one of the boards where they barely fit to start.  No fun. 

Others I've had apart are easy and fun to work on.  They pull in and out, solder comes out easily, in a lot of ways they're easier to work on than eyelet boards.  I dunno if there's a date, or a board serial number that identifies which is which, but if you start replacing components, and you start running into issues, I would just button it back up and play it or sell it.  Some just aren't meant to service.

As far as the transformers, I think they are well built, and sturdy enough for any application within their voltage and current requirements.

[jered1011]

I did this  https://luigiretro.com/HRD2ODS_retrofit_pcb  to mine. Took out the stock speaker and put in an evm12l and this amp is a monster! Live its incredible and recording to, I couldnt be happier. The on board trimmers allow you to dial in your clean, dirty, and boost channels exactly to your liking. I have no affiliation with this product, just a very happy customer

[scstill]

Sure, you can re-use transformers and speakers

The AB763 is a Tube Rectifier and the HRD is not.