A question about the original design of Sunn Amps

[Oldplayer]

I recently read someone's comment on a forum that the original Sunn amps were based on Dynaco kits that were tied together somehow. Is there any truth to this? If so, has anyone built a Dynaco kit that sounded anything like the original Sunn amps? It sounded pretty far fetched but it was something that made me curious about why someone isn't building repro Sunn amps these days. Sunn amps that I played with in the early '70s were monsters and I haven't had anything quite like them since.

[Steve Conner]

Yes. The early Sunns had a Dynaco power amp chassis in the bottom of the cabinet, hooked up to a preamp in the top with a bundle of wires.

Dynaco Catalog History

It has come to my attention that many old versions of the Sunn musical instrument amplifiers (such as the 1000S and 2000S) used Dynaco transformers for their power amplifier stages, and some of them (the 100S and 200S, for example) actually contained most of the guts of a PAM-1 and Mk. III system! This is apparently only true of the earliest units; they were replaced by Dynaco clone transformers and similar circuitry from Western Transformer Co. during later production runs. This information was revealed in an interview with Conn Sundholm, founder of Sunn.

[Oldplayer]

What you said about the preamp just made me realize that there's more to just building an amp kit. By the time you build the preamp and the amp kit, build a cabinet, and then add speakers, you could have more invested than if you found an old Sunn amp and restored it. I think I just talked myself out of building a kit.

[Tom Phillips]

Yes. The early Sunns had a Dynaco power amp chassis in the bottom of the cabinet, hooked up to a preamp in the top with a bundle of wires.

And I believe that Sunn continued to use the Dynaco PA circuit for a time after that. The circuits were published in the Dynaco transformer catalog. Brings back fond memories. Interesting fact about the separate PA chassis Steve. I haven’t tripped across one of those to date.

[trobbins]

Bass players were impressed by the relatively better bass low frequency extension offered by the Mk3, which being aimed at hi-fi, had pretty much flat response to well under 40Hz. I have an Australian 1964 guitar/instrument amp that was exact clone of the Mk3 - probably for the same reason as Sunn did from 1965. The Mk3 was introduced in 1957, so had a good folowing by mid 1960's.

[soundmasterg]

I'm friends with Conrad Sundholm, the co-founder of Sunn and I've asked him a lot of questions over the years about those days. Pretty much the earlu Sunn 'Smiley Face' amps with the controls on top and the Smiley Face logo were a Dynaco Mk3 power amp chassis, and a Dynaco PAM 1 preamp chassis, stuck in a box with a Sunn logo on them. Later they changed to having one chassis in the head instead of two, and when they did that, they also had an engineer they hired revoice the circuits a little better for bass and guitar. They were still using Dynaco transformers at this point. Then the big amps like the 2000S came out, which again used Dynaco transformers. The early ones of these amplified down to 10Hz!! Later around 1970 they changed to Schumacher transformers across their line, and these amps had higher voltages and a bit of a different sound...less sweet with more power. I believe they also changed from KT88's to 6550s at this time, but there are no records anywhere, and Conrad doesn't remember all those details because by this time he was heading a company of like 140 people or something and didn't get involved in the nitty gritty sometimes. Then later he sold the company and Sunn got more into solid state and PA stuff only to eventually get bought by Fender.

The old tube Sunn stuff is great. Very well made and good sounds. I don't like their amps for guitar much though they are ok and better than a lot of stuff. For bass, the old Sunn stuff is stunning. My favorite bass amps if I want the old tube bass sounds....

Greg

[Amp Kat]

I reworked one for somebody one time and revoiced it to fender blackface specs and it sounded great. I actually tried to buy it from hiom but he didn't want to sell it. The 7199 Pentode/Triode was a very interesting setup and IMO gave that amp it's Bass feature but this particular amp had Dynaco's that were both fried to a crisp and I used nice Fender trannys as replacements and the tremelo and reverb still worked thankfully as I would have never found those parts to fix it if they were bad. They were quite amazing amps tstl.