The Amp Garage

Hi all, I have been on a rabbit hole recently. I found out that Peavey changed the OT of the Mace over time. I know there were two versions as well, VT Series and 320T, although I've seen 4/8ohms OT taps on both versions Looks like some of the VT series were changed from 4/8 ohms version (pics and s...

Many thanks all for the inputs, links and suggestions. Great reading material and food for thought. I sent a note to heyboer about their OT. Also I have been speaking to Hammond about their sunn PT, and for future reference they did a transformer based on someone's spec request and never had access ...

This Peavy OT at 2.1k is looking like a good candidate

https://www.tubeampdoctor.com/en/output ... -6505-6534

Hello -- If the Sunn amp in question is from early 1970s it would be an A451 as mentioned a few years back in the thread, it has 2k2 primary along with UL wiring. The power section in Sunn's schematic for the 2000s is an example. Literally copy/paste of Dynaco's quad pentodes UL design target 200-2...

Thanks again for the input Martin. It's my first time looking at non Fender style transformers, and the 6550 has always been on my list. One other option I Iooked at is the Sunn OT which has 2.5K primary. I think it's wired Ultralinear and probably putting 500V+ on plates. I never tried UL wiring an...

I was checking the 6550 spec sheet on this thread and for class AB, two matched tubes and fixed bias the recommended primary at 450V is 4K. I am thinking of building an amp with 525V (plates) so a bit higher. But for a quad of tubes the primary at 450V is half = 2K. I am wondering if the primary sh...

Reviving this old thread. I was checking the 6550 spec sheet on this thread and for class AB, two matched tubes and fixed bias the recommended primary at 450V is 4K. I am thinking of building an amp with 525V (plates) so a bit higher. But for a quad of tubes the primary at 450V is half = 2K. I am wo...

<r><QUOTE author="ijedouglas" post_id="445953" time="1667327856" user_id="17512"><s>[quote=ijedouglas post_id=445953 time=1667327856 user_id=17512]</s> No idea, not sure where I got the pic from either. It looks like 2 Dumbleland 300SL on the left with an ODS on the right... <e>[/quote]</e></QUOTE> ...

Hi Sergio, That was a guesstimate from the photo copies. Rafael did a great schematic after more info was available. The one I built worked out fine, I built another version and it was a nightmare. Couldn’t get the right balance volume wise and had a horrible thumping sound. Went completely differe...

This is correct, same happens in fender amps with that circuit. It's because you have a low resistance to ground and hence bleeding a lot of signal

Which schematic did you use?

As we approach end of Oct and there has been no response I am assuming this is no longer available?

Moderators, maybe worth deleting this thread as it seems not being offered anymore?

Did you ever do this run? I'd be down for one or two

johnnyreece wrote: ↑Fri Sep 16, 2022 5:35 pm Thanks for chiming in with a follow-up! I wondered how this turned out. Glad you didn't give up!

I thought about giving up to be honest, but just needed some time away from it and distance. I'm glad it worked out and hopefully it will help others in the future

martin manning wrote: ↑Fri Sep 16, 2022 5:41 pm

Bombacaototal wrote: ↑Fri Sep 16, 2022 4:41 pm...plus the standby pot was loose and this was replaced

Standby pot?

Thanks for the update!

Sorry, switch