1960-62 Dallas 30 Amp Mystery

[rozrosner]

A while back a fellow in Spain posted some information in this forum about an amp restoration project he was working on, with a schematic he drew of the power section and some pics of the preamp. It was a Dallas, or Rangemaster or Shaftsbury 30 amp (the same amp was marketed under all those brand names, I believe). There was a thread going, but the thread just died, and the gentleman apparently never posted his preamp schematic.

I played one of these years ago in Michigan, and I've been fascinated with the amp ever since, but they are apparently very rare and I still have been unable to find a complete schematic of it. Besides using eliptical speakers and a plastic cabinet, the most distinctive thing about this amp was that it had this great gritty overdrive sound using two EL34 output tubes (apparently in push-pull), at very low volume. This is the only dual EL34 amp I've ever played or heard about that you could crank up in a coffee shop and not even rattle a saucer!

I had a chance to purchase the one I played, which, for all I know could have been the only one in the US, but I could not justify the expenditure given that it was so low powered. It was probably not even as loud as a Fender Champ!!

Does anybody have any information about these amps? I really want to know how and why the amp was not louder given its use of two EL34 tubes. Even if it was a parallel, single-ended amp, it should have been much louder. Maybe the two eliptical speakers were so horribly inefficient that it turned a loud amp into a bedroom amp?

Of course, if one can get great EL34 tone at very low volumes by using inefficient speakers, why are so many people building amp attenuators and dummy speaker load devices and master volume circuits and all that stuff when all you need to do is design speakers to be as inefficient as necessary to give you the tone you want at the volume you want?

Or is there something else going on in these old Dallas amps? It seems like almost every dual EL34 amp I've ever seen except this bizarre Dallas 30 is about 50 watts, and this one sounded as if it was 3 watts!!!

Please help me solve this mystery. I want to try building one or having a friend of mine build one for me, but I want it to be a bit louder than the one I had the chance to buy years ago (but not nearly as loud as a 50-watt Marshall of Vox AC50).

Obviously, I'm not an amp tech and I hope my questions are not too obvious for this forum. I built one amp from a kit last year, but, other than that, I'm a novice at this stuff.

[cservonyec]

Hi Rozrosner.
I am after the same thing, but this spanish guy 'chocopower' or something gone awol. You can see the power section of this amp, it is well drawn out, plus you can verify it from the picture too. I am more interested in the preamp section as I need to rebuild my tremolo of my Dallas amp. I've posted some interior pictures of my amp. However it is difficult to figure out the tremolo circuit. It is a mixture of the Vox AC10 and a Selmer Twin 30 I think.
My amp when it worked and before it was stripped of it's components, sadly didn't do a drawing then, it was very low output. I took it to Chandlers to repair it's tremolo as it didn't work, but the guy couldn't fix it however he said the output was just about 3Watts. Considering it had two miniature 6V6 tubes in push pull, I was intrigued. It could be that it was wired in triode mode. Just a thought. Let me know if you come across any Dallas Rangemaster amp schematic, not the Rangemaster pedal though. Recently on ebay I've seen a couple of them sold, even contacted one of the winner about the schematic, he promised but unfortunately nothing happened.
That's life.

[Enzo]

HI Roz, welcome to the forum. We had some personal discussion of this, so I won;t duplicate that here.