- Posted by Lynn Olson (M) on August 25, 2004 at 21:03:20
In Reply to: Claus Byrith's 30w PP posted by beaufortralph on August 22, 2004 at 14:04:49:
And borrow a classic amp from the 1950's and try it on your speakers. Frankly, I think Sansui speakers are pretty much bottom-of-the-barrel, no better than Radio Shack's offerings, but you'll still hear the obvious difference between the solid-state you're used to and the borrowed tube amp.Keep in mind most 1950's and early 1960's products were quite similar in circuit design, with Williamson/Dynaco variants being the most common by far. These are characterized by Class AB push-pull pentodes with 20dB of feedback, a Williamson-style front end, and the EL34/6550 outputs either driven by a dedicated driver stage (Williamson) or directly off the phase splitter (Dynaco). Some have solid-state rectifiers, some have tube rectifiers, some have circuit boards, some have point-to-point wiring. All of these affect the sound to a degree.
Nevertheless, the basic character of all the vintage amps is pretty similar, since the circuits and selections of tubes are similar. There just aren't that many ways you can build a Williamson or Dynaco amplifier. There are also amps that are a little bit different, like the Quad II, McIntosh, Acrosound, or Citation II, but these are collectible and priced accordingly. They still use 12AX7's, 12AU7's, EL34's, or KT88/6550 tubes, so the "flavor" is recognizably vintage.
The amps you see in this forum are quite different, and aimed at folks aren't into the vintage sound. Interstage transformer coupling is more expensive, and precludes (global) feedback, which is why it was almost unknown "back in the day", when every amp had to have feedback to stay competitive in the spec race.
If you're just getting started, I wouldn't jump into the deep end of the pool first thing. Get acquainted with tube sound - there are thousands of stock and modified Dyna Stereo 70's out there, which are perfectly respectable amps then and now. The traditional favorites of Scott, Fisher, Eico, and many other are all good. Interestingly, the vintage Sansui tube amps were quite good - although the Pioneer and Trio/Kenwood amps were pretty mediocre.
If you're buying, get a unit that's already been restored by somebody that knows what they're doing (suddenly turning on a vintage amp that's been off for the last 20 years will almost certainly blow out the power transformer - old electrolytic power supply caps require a "reforming" procedure first).
Follow Ups:
- Re: Save yourself a lot of time and effort - beaufortralph 06:16:41 08/26/04
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- In Reply to: Save yourself a lot of time and effort posted by Lynn Olson on August 25, 2004 at 21:03:20:
Lynn,
Thanks a lot for the reply. Vintage gear is not my interest. My interest is in building my own gear and ending up with a setup that sounds very good. I do like tube equipment. I have a late 1960's vintage ham radio transciever that i salvaged from the dumptster and repaired. I love to use that rig.
I realise that the speakers I have are less than ideal - but the friend who left them to me brought them back from Vietnam - and they will be replaced by homebuilt units in time, but I do not have the resources of time nor money to build super sensitive, super expensive speakers.
I must decide which amps to build - the CB 30 or Kevins "upgradeable" KT88 monoblocks. Any suggestions?
- Sansui - PeterP 18:11:25 08/29/04
(0)
- In Reply to: Re: Save yourself a lot of time and effort posted by beaufortralph on August 26, 2004 at 06:16:41:
I still have my pair of Sansui SP-3500 (1974). I must admit that when it comes to everything except "crank-it-up and party" I like my Pioneer full-rangers (http://www.melhuish.org/audio/DIYBX16.html) better, the point is that it really doesn't have to cost a lot and speakers really do make the biggest difference. Hell, I ran my Sansui's for about 30 years and was quite happy. They still remind me of a different time. You're asking for opinions. Everyone's got one so here's my two cents.
Once you get the bug to build amps, it just doesn't stop. Don't think that this will be your "last and final" amp. If you like building amps, you'll always want to try something new and different. So for this build I'd go with the one that stays as close to fully differential as possible. IIRC (I didn't look it up) I think that Kevins "upgradeable" KT88 monoblocks fit that bill.
I quite honestly think that building speakers is the better way to start (this is your second amp) but I wouldn't listen to my own advice. I like building amps MUCH more that building speakers.
So just Build, Listen and Learn.Enjoy,
Pete.
- My recommendations - KevinC 06:38:33 08/26/04
(1)
- In Reply to: Re: Save yourself a lot of time and effort posted by beaufortralph on August 26, 2004 at 06:16:41:
I have proposed to Ralph a phased project that starts with a very modest Mullard-style amplifier using a 6SN7GT as a voltage amplifier, a 6BX7GT as a phase-splitter/driver and a pair of KT88/EL34 output tubes. With the purchase of a pair of output transformers and power transformers, Ralph can get started with a respectable design that will sound better than most vintage amps at a cost that is not bank-busting. If he continues to have interest in improving his amps, the same tube count and power supply configuration can support a fully transformer-coupled p-p amp, similar to the designs that I and others favor.
There's no denying that transformers are expensive, so this route makes stepwise expenditure without obsolescence possible. Sure, I'm tempted to argue that a choke loaded PS or a phase-splitting input transformer is a necessity to get the best sound..., however we all had to start somewhere. I never have understood why a few people feel that their lives are not complete until they've climbed Mt. Everest, so why should I insist that all amps look like mine just because I think that it's the topology to have? It's better to build something than to sit and plan the ultimate thing and never build anything.
Kevin Carter
K&K Audio
www.kandkaudio.com
- good advice - keto 08:25:16 08/27/04
(0)
- In Reply to: My recommendations posted by KevinC on August 26, 2004 at 06:38:33:
The strapping together of a breadboard can be an afternoon project, and a funky looking breadboard sounds a lot better than a drawing of the "perfectly resolved" schematic does. Very good advice, there... --keto
- good advice - keto 08:25:16 08/27/04
(0)
- Sansui - PeterP 18:11:25 08/29/04
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