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Most popular SET amp

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Posted on May 8, 2015 at 12:11:44
mark.korda@myfairpoint.net
Audiophile

Posts: 1253
Location: Maine
Joined: August 16, 2011
 Hi, is there a SET tube amp out there that has gained a popularity with the single end crowd like the Dynaco 70 did with the push pull? I'm looking for affordability,longevity,and tank like build. Kit or no kit also. In your view, what might that amp be? Also, were most old Bakelite tube radios SET's cause they sounded so good? Thanks for any input....Mark Korda.

 

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RE: Most popular SET amp, posted on May 8, 2015 at 12:25:32
Paul Joppa
Industry Professional

Posts: 7296
Location: Seattle, WA
Joined: April 23, 2001
 Dunno about the rest, but I'm pretty sure that old radios were SE because tubes themselves were really expensive.

 

RE: Most popular SET amp, posted on May 8, 2015 at 12:27:44
danlaudionut
Audiophile

Posts: 5480
Location: Schenectady
Joined: June 6, 2002

Mark

I would say the Bottlehead Amp Kits.
Paramount
http://bottlehead.com/?product=paramount-v1-1-300b2a3-monoblocks-pair-kit
Stereomour
http://bottlehead.com/?product=stereomour-stereo-single-ended-2a345-integrated-amplifier-kit

DanL



 

Wavelength Cardinal andArt Audio Jota, posted on May 8, 2015 at 12:50:00
Jay Buridan
Audiophile

Posts: 10284
Location: Michigan
Joined: January 21, 2004
 These are both tanks but not cheap if purchased new.

"Horse sense is the thing a horse has which keeps it from betting on people. "
― W.C. Fields

 

Korneff 45 SE, posted on May 8, 2015 at 16:24:54
Rick R
Audiophile

Posts: 723
Location: San Diego
Joined: June 24, 2002
Contributor
  Since: September 22, 2003
 I would say that the Jeff Korneff 45 SE is a SET standard of sorts. Built like a tank, reliable and sweet sounding. Because it is only 2 watts, it requires appropriately high efficiency speakers, so some might shy away from it. Do a search and see all the high praise from many folks. I am sorry I every sold mine. It was the second SET amp I owned and have owned many since. If I could give advice to my younger self, it would be "keep the Korneff amp and preamp forever". I could have save thousands of dollars if I heeded that advice. I recall the original design was from a magazine article (do a search) and that Jeff modified it somewhat. I do not know if Jeff is still making amps. There are lots of Korneff 45 Clones out there, some very well made, so the schematics must be out there also. The Korneff 76 preamp is absolutely superb and complements the 45 amp like a hand in a glove.

Here is a link to a previous post on the design:

 

AFAiK, most old radios were push pull, posted on May 8, 2015 at 17:55:17
samtellig
 More bang for the buck. Less expensive transformers required with PP.

Many console radios (pre WW2) used a pair of output tubes such as the 45 or 2A3 to deliver something like 4 to 6 watts push-pull.

I have found lots of old radio photos online, but not much on SE vs. PP.

Any antique radio experts out there?

 

RE: AFAiK, most old radios were push pull, posted on May 8, 2015 at 20:42:24
Triode_Kingdom
Audiophile

Posts: 10049
Location: Central Texas
Joined: September 24, 2006
 I don't think push-pull came into widespread use for consumer audio until well after the war. Even at that, the great majority of tabletop radios I've seen from the '50s and '60s were single-ended.

 

RE: AFAiK, most old radios were push pull, posted on May 8, 2015 at 20:59:02
mark.korda@myfairpoint.net
Audiophile

Posts: 1253
Location: Maine
Joined: August 16, 2011
 Hi, great answers and info! Thanks you guys...Mark

 

No, those days are gone, posted on May 9, 2015 at 00:24:12
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
 If you mean based on sales and press. The SE crowd - in the North America - is small and probably more than 50% of the amps that do get built are DIY and not commercially available.

My SWAG is that AN(UK) is the biggest "reputable" SET company producing high quality SET amps in the Audio Market, but they are small and Fi Audio is the smallest.

And if you ask which is the best SET amp, you'll hear the names of Japanese producers and the handful of US pioneers that revived SET in Sound Practices in the 90s, of which only a few have become commercial builders. There is also a second generation, "sons of the pioneers", most of whom are custom builders, like Jeffrey Jackson.

At least that's my impression.

I would be interested in knowing the social network connections behind Bottlehead: Doc, Paul, and fairly recently, Caucasian Blackplate.

 

RE: No, those days are gone, posted on May 9, 2015 at 00:46:29
Paul Joppa
Industry Professional

Posts: 7296
Location: Seattle, WA
Joined: April 23, 2001
 ..."I would be interested in knowing the social network connections behind Bottlehead: Doc, Paul, and fairly recently, Caucasian Blackplate."

Maybe some day I - or Dan - will write up a history; here's the short summary:

Dan was tired of using his Berkeley physics degree to bake muffins, and started a vintage audio club. As SETs appeared on the scene, I learned about and joined the club and it turned more in the direction of SETs. That led to "Electronic Tonalities", precursor of Bottlehead. I was getting tired of my corporate job and started designing for Dan, who had become a good friend by then. PB was involved as a customer first; I'll let him fill in the rest.

 

RE: Most popular SET amp, posted on May 9, 2015 at 01:56:18
RGA
Reviewer

Posts: 15177
Location: Hong Kong
Joined: August 8, 2001
 I suppose it depends where you live - but no there is no single big seller that is revered by most. Largely because when the ST70 was selling tube amps were not "dead" in the mass market. Tube amps today may be fairly popular but ONLY popular within a niche. And SET amps are probably a niche within the niche.

I suppose Bottlehead because they're kits and affordable. The Audio Note Kit ONE has been selling pretty well for a long time - they have different outlets selling the kits in different countries - there is one out of Canada ANKits and one in Hong Kong etc. The Kit One is a 300B SET. But its price takes it out of budget for most and rules it out as being a big enough seller.

 

RE: Korneff 45 SE, posted on May 9, 2015 at 02:18:12
jusbe
Audiophile

Posts: 5950
Location: North Island
Joined: April 4, 2000
 Does he make these any more?


Big J

"... only a very few individuals understand as yet that personal salvation is a contradiction in terms."


 

WE 91A Clones Honorable Mention at least, posted on May 9, 2015 at 06:03:50
Sebrof
Audiophile

Posts: 634
Location: AusTX
Joined: July 12, 2002
 As far as circuits go, the Western Electric 91A clones, 300B and/or 2A3 seem to be quite popular. That may be because I have one and so I pay more attention to them.
I don't know of any manufacturer who makes and sells them, I believe every one of them is DIY.

 

Maybe we're both right, posted on May 9, 2015 at 07:35:37
samtellig
 Maybe most of the 1930's console (floor standing) radios were push-pull, while the majority of tabletop radios were single-ended.

No doubt about the sound quality, though.

 

+1 and another one to consider......, posted on May 9, 2015 at 09:22:15
gilmorneau
Audiophile

Posts: 288
Location: Colorado
Joined: August 10, 2004
 Commercially available SET hifi amps are numerically small compared to all the other stuff out there. Just go to a hi-fi show, you'll see. I'd wager that the majority of the SET amps in the world are DIY; either kits, scratch-built, or very small scale manufacturing by artisan builders.

It's probably more useful to consider design topologies, rather than specific manufacturers, when trying to determine the most popular SET amps. When you look at it that way, the Western Electric 91A clones (or, more generally, pentode driver, triode output) are definitely among the most popular. Maybe even the most popular. Hard to say.

Another big contender for most popular would be the Loftin White type (or, again more generally, two-stage direct coupled). There are lots of these around the world. Maybe more than the above.

The only other one that comes to mind as super popular is the two stage, low mu triode input/driver coupled to triode output design. Probably not as many of these as there are 91's and LW's, but there's still a lot of them.

There are other designs (IT coupling, etc) that will find recommendation from many, but in terms of sheer popularity, there are probably fewer of these types of amps out there.



 

+2 for the M91, posted on May 10, 2015 at 00:57:43
Paul Joppa
Industry Professional

Posts: 7296
Location: Seattle, WA
Joined: April 23, 2001
 That amplifier kicked off the modern SET revival and its basic topology has remained popular - easily the longest-lived design. I agree that DIY is more central than built amps or kits, so it's the most comparable to the ST-70 kit. Still, the comparison is stretched given the enormous number of ST-70s sold back in the day!

 

RE: WE 91A Clones Honorable Mention at least, posted on May 10, 2015 at 03:28:00
vinnie2
Audiophile

Posts: 4481
Location: North Carolina
Joined: September 28, 2013
 I think the Joe Roberts build article on the 91A clone in SP #1 had a lot to do with that. For anyone that wanted to build a good SET amp (then or now) there it was with all the info you needed. Plus the 300B is a terrific tube now that there are other brands besides the WE available that sound good.

 

RE: Most popular SET amp, posted on May 10, 2015 at 06:43:53
hifipaul
Audiophile

Posts: 735
Location: NY
Joined: December 22, 2008
My favorite SET amp is the whichever one I just finished building. Proud papa syndrome. Then on to the next one. My next favorite will be SET 10y.

I even have a SEM; Single ended mosfett. Slated for revisions but still makes music.

From my junk-box collection; SET 6CK4 is my favorite. Cheap, easy to use, and good sound.

 

By 1929-1930, most old console radios and consumer audio amps were push pull, posted on May 10, 2015 at 11:27:20
Interstage Tranny
Audiophile

Posts: 3063
Location: Eastern
Joined: October 4, 2006
 In 1928, we still had SE 205 amps from WE plus SE 210 and 250 amps from RCA. However, push-pull amps also appeared in 1928, with much larger numbers of pp by 1929. Of course, the "large numbers" of folks back then were first discovering the sound of the airwaves as well as the sound of amplified phono or reproduction. Public address was also developing very quickly...

Make no doubt about it, though, the birth of hifi was born by the transformer companies. Retrofitting better grade trannies to your "radio outfit" guaranteed "better...more realistic sound" according to many ads of that era. Every major USA tranny manufacturer offered kits and/or high grade parts by 1928. I have some 1928 trannies that are absolutely high fidelity; even by today's standards. These units I speak of were available for consumer home hifi; not necessarily commercial usage. Most of these published amp schematics offered by tranny companies were already push-pull in 1928. By 1929, besides the few "known" SE classic amps like Loftin-White, RCA or WE, Push-Pull was well established as the norm...

The WE 42 and 46 theater amps appeared in 1928; both used PP 205. WE's 205 tube was closer to a 210 by RCA, compared to RCA's 245 or 250. I have always found it very interesting that any development by RCA or WE was soon mimicked by the other. While the VT-1, 101, 102, 104, and VT-2 WE tubes are considered their "earliest" studio or broadcast line level or opt tubes, RCA had their UV-199 and UV-202 at the same time period as the WE VT-1. WE also had a thin input tube similar to the RCA UV-199. Line level and preamp tubes by WE were not much different than the venerable RCA UV-201. The RCA UV-202 appears as the WE VT-2 appears. When the RCA 210, a development of the UV-202 flourished, the WE 205B tube appears.

While TK is right that tabletop radios were still the hold-outs of SE for a few more decades, as of 1930, there were very few SE amps offered with hifi in mind; especially to the public. BTW, the WE 300A and WE 91 came about in the early 1930s; after the RCA 250 tubes and amps. By 1933, the WE opt tube of choice was the 300A; while RCA offered the single plate 2A3. 1933 is also significant as the demise of GL globe/balloon (and tennis ball) shaped tubes. Most interesting, is the fact that all RCA tubes were always offered to the public (consumer), while the WE tubes were not offered to normal consumers. WE tubes could only be purchased from certain distributors; usually reserved for studio, broadcast and theater contractors and engineers...the early "soundmen" as we fondly speak about...

 

WE 91A Clones all seem to Omit the Feedback of the original 91A amps..., posted on May 10, 2015 at 11:51:04
Interstage Tranny
Audiophile

Posts: 3063
Location: Eastern
Joined: October 4, 2006
 How many of you built your 91 clones with that feedback loop included ?

That feedback was a terrific bandwidth extender. The first SE amps I made in the mid to late '80s were built on Thordarson T-30W08 chassis. Without that feedback loop, (also considered a tone control by some), the amps had flabby bass with little oomph. Add, or switch in that loop, presto change-O, better bass and dynamics instantly; especially with mid-grade opts like the early WE, Thordarson, UTC, Samson, General Radio, etc....even the early Peerless offerings to replace the WE 91 SE tranny...Keep in mind that theoretically, if a feedback loop is "before" the opt tranny, the opt is not considered to be part of the loop. Yet, sonically, the WE 91A (300A tube's plate to 310A screen grid) feedback makes quite an impact...

Also, looking closely at the Loftin-White scheme circa 1927-1929, the "raised" voltage on the opt tube filament(cathode) is connected to the front end input tube's plate...certainly considered a feedback loop by many...Connecting certain amplifier power supply caps' negative return lead to an output tube's cathode is also considered feedback by many soundmen...

So folks, please do not underestimate the potential benefits of all topologies...feedback included....

 

RE: No, those days are gone, posted on May 10, 2015 at 12:11:09
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
 I was repairing used Hifi gear from thrift stores in high school, which I would fix up and sell to the local Hifi shop. At some point, some 300B Bottlehead amps came into my possession (not for repair, but rather as a very good deal). The single ended tube amps sounded a lot different (in a good way) than anything I had repaired or owned, and thus my interests in single ended tube amps began (I was about 17 at the time).

After enough self education, Doc B. allowed me the privilege of working with Bottlehead (and driving PJ to the office periodically).

I believe Don is retired now and no longer making amplifiers.

 

More than feedback was omitted, posted on May 10, 2015 at 12:27:12
Sebrof
Audiophile

Posts: 634
Location: AusTX
Joined: July 12, 2002
 I've seen what I believe is the "real" WECO 91A schematic, and there's a lot in it that is not in my clone. It's actually quite complicated compared to the one I built IIRC.
But I'm guessing that the feedback loop is the most impactful piece that's been omitted by most builders.

 

RE: WE 91A Clones all seem to Omit the Feedback of the original 91A amps..., posted on May 10, 2015 at 13:25:19
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
 Do better OPTs these days take care of most of that?

 

Don has retired!, posted on May 10, 2015 at 13:31:15
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
 I hadn't heard that about Don. Too bad. Good thing I bought a pair of his 2A3/45 monos a few years back. They are a delight and to my surprise, they aren't too noisy when run through a resistive speaker-headphone adapter and still sound lovely.

 

Cascade 6SN7 drives DHT, posted on May 10, 2015 at 18:36:03
91derlust
Audiophile

Posts: 1101
Joined: December 25, 2014
 6SN7-6SN7-300B/2A3... Another design popular during the SET resurgence back in the day. Herb Reichart's Flesh and Blood and JE Labs were (very) popular DIY designs... as was the Horus on the MQ site; Sun Audio, Welbourne and a many others the 6SN7 cascade in production amps.

Of course, the WECO 91A (and similar) and L-W were also important...

But, as others have said, there is plenty of variety in the subset of a subset of a subset area of interest.

Regards,
91
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

Look to the orient, posted on May 10, 2015 at 20:08:50
k-k-k-kenny
Audiophile

Posts: 552
Location: Melbourne
Joined: May 5, 2007
 I'd wager there is more SET fanaticism in Japan & China than anywhere else. None are readily "affordable", but the obvious Japanese candidates include:
Luxman MB-300 monoblocks from 1983-4
Wavac MD-811
Wavac MD-300 (and from there on up to well past $100K for the SH-833)
Air Tight ATM300 or ATM21
Shindo WE 300B or Cortese F2A

Of these the baby Wavacs are the least expensive.

Line Magnetic in China are doing interesting things with 300B, 45 or 212 tubes - again, at a price.

 

RE: WE 91A Clones Honorable Mention at least, posted on May 10, 2015 at 23:56:51
danlaudionut
Audiophile

Posts: 5480
Location: Schenectady
Joined: June 6, 2002
 Here is the article

DanL



 

RE: WE 91A Clones all seem to Omit the Feedback of the original 91A amps..., posted on May 11, 2015 at 00:15:54
91derlust
Audiophile

Posts: 1101
Joined: December 25, 2014
 Maybe a little...

It is my understanding that the inherently high output impedance of the pentode driver causes the freq roll-off when driving a DHT. This is not necessarily a "bad" thing, and may actually be beneficial in some systems.

I run a tube DAC (real tube output, not buffer) and use a 6C6 to drive a 2A3 and there should be some roll-off - maybe -3dB at 20kHz - but I don't find it obvious; the high frequencies are resolved and plenty present for me. I could easily run some +ve feedback, but don't feel the need.

Regards,
91.

"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein

 

RE: Look to the orient, posted on May 12, 2015 at 05:53:02
LewinskiH01
Audiophile

Posts: 234
Joined: December 7, 2008
 What do you guys think of Yamamoto A-08? And Coincident Dynamo 34se? I realize the latter is a SEP, but how does it sound?

 

Most of the radio's I worked on were 45 or 71A, posted on May 13, 2015 at 09:41:08
Gordon Rankin
Manufacturer

Posts: 2928
Joined: June 9, 2000
 Tom, others

Most of the radios I worked on here were either 45 or 71A single ended, only a few 2A3's. Most of the early RCA, Crosley and other bakelite units were single ended. I don't remember any of these being pp.

But they are not really hi fi either. The outputs look like they are good to like 80hz, like most guitar amps that are single ended.

I did have a cool japanese radio that had line inputs, silver mica coupling caps and ECL82/6BM8 output tubes. It was really sweet and someone had to have and I have too much junk here already.

The WE stuff early on was not sold to anyone. It was all leased and WE and then Altec serviced all the equipment. They put those damn 91A amps in almost anything. I was called ounce from some guy who was redoing a house here in Cincinnati (Lindner's) they had a PA system in their house run by 91A amps. Hadn't been used in years, scored a couple and a boat load of 300B's, 274 and other tubes.

Thanks,
Gordon
J. Gordon Rankin

 

RE: Look to the orient, posted on May 17, 2015 at 03:19:01
LewinskiH01
Audiophile

Posts: 234
Joined: December 7, 2008
 What do you guys think of Yamamoto A-08? And Coincident Dynamo 34se? I realize the latter is a SEP, but how does it sound?

 

No Don Garber is still working, posted on May 20, 2015 at 23:52:39
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
 You may have confused him with Don Allen in Arizona. Don Garber is out of Brooklyn, NY.

 

RE: Most popular SET amp, posted on May 25, 2015 at 14:59:21
rebbi
Audiophile

Posts: 288
Location: Austin, TX
Joined: September 4, 2008
 Audio Note Kits out of Canada has been selling (and upgrading) the Kit 1 for about 10 years, and the design is around 20 years old. I built one this past winter and am absolutely thrilled with it. I had a weird (unprecedented, actually) problem with my output transformers at one point and Brian Smith who owns ANK provided stellar service in sorting out the problem. As RGA said, these kits aren't cheap, but considering that this is an integrated, one-box solution (if that's what you want) it's priced competitively with other offerings. For example, at regular prices, the Kit 1 is slightly cheaper than a pair of Bottlehead Paramounts and a Bee Pre preamp. I have no beef with Bottlehead, by the way. I have been running one of their Seduction phono preamps for several years and it's been great. Also, Bottlehead's customer service (and user community) are great resources and their assembly manuals are stellar. But I am actually pleased at this point to flip only 1 power switch to play music, rather than 3. ;-) And the sound is heavenly!

 

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