Opinions on 2A3 Push-Pull amps?

[seanrr]

I have a 2A3 SET amp I love, but I have been looking at a 2A3 push-pull amp that looks pretty enticing. Does the 2A3 retain its magic in push-pull configuration? I am looking to drive some Tannoy 15" Golds, and I am thinking a 2A3 push-pull amp might be as nice or nicer than a 300b SET. Opinions?

 

[thorpej]

All push-pull amps have most of their even harmonic distortion cancelled out in the output transformer... so if you like the high even harmonic content, you might be disappointed by a push-pull amp.

 

[Joe Roberts]

PP 2A3 is definitely a good plan. Still very colorful if maybe a bit more controlled than SE. Lots more drive. much better bass.

Realistically, not many speakers run well on 3W, although you can get sound out of them. The Tannoys would surely benefit from a few more watts.

I've been planning to build a PP 2A3/6B4G for years but keep getting sidetracked, this time by a WE275A kit amp my friends in Korea organized, a very expensive 3 watt SE project, basically 2A3ish.

 

[seanrr]

Any opinions on how a 2A3 Push-pull would compare with a 300b SE amp? I think they would both be in the 7-9 wpc range.

 

[nerdorama]

I have a PP 6B4 amp on a breadboard. It's interstage coupled with a LTP front end. I think it's a great sounding amp. Very clear, good bass, excellent low level detail. It's a pretty simple circuit other than a CCS for the input stage cathodes. Transformer choices are important.
John

 

[garr]

I have Sun Audio PP 2A3 monoblocks and Sun Audio 300b SE amplifier.
The SE 300B sound I like much more.
Review on these monoblocks can be seen here:
http://www.enjoythemusic.com/magazine/equipment/0101/sunaudiosv2a3pe.htm
My impressions about sound Sun Audio PP 2A3 monoblocks coincide with the opinion of the author.
Igor

 

[Poultrygeist]

Stick with a SET which unlike most push pull amps they don't employ negative feedback to gain higher power.

 

[JimW]

Stick with a SET which unlike the push pull amps doesn't employ negative feedback to gain higher power.

I have a pair of "Amity" style push pull 2a3 amps (Lynn Olson inspired). There is no negative feedback employed or needed. I used all Lundahl iron except for filament transformers. They are a good, solid 8 watts. They are drive either Altec or Mark Audio speakers. There is no audible hum, even with the Altecs. I have them alongside 2a3 set, 300B 91a knockoff (thanks Joe R. for the inspiration on that one), and a pair of 300B "Legacy" (T.Loesch) monoblocks. Other amps in the stable include PP el-84, Fisher KX200, and Mac 60's. In my opinion, the push pull 2a3 do everything that 8 watts can do well, which is quite a bit. The bass is cleaner and tighter than the SE's, they are quiet, and give up absolutely nothing in terms of low level detail. The downside to this particular design is it is hard to drive. I built the "Raven" linestage to drive them, and the combination works very well, and has for about ten years now.

 

[bimasta]

I have a PP 2A3 amp, 15W, made by Cary. It was their first product and so good it put them on the map. Several high-end dealers in New York told me "it's the best amp in the store." I'm told one advantage of PP over SE is that the quality of the tube isn't as critical — a $75 2A3 may sound as good as a $400 2A3 in a PP configuration. I don't know the technicalities, but I know it's the most beautiful sounding amp I've ever owned.

 

[bean_counter]

I have had a pair of DIY 6B4G monoblocks in my system since 1999; transformer phase splitter coupled, no feedback. Nothing has displaced them, not even a 300b amp with WE 300b's.

My personal opinion - and I know I'm in the minority - is that most of the 'magic' is in the direct heating, vs the single ended. I admit that PP gives up a bit of midrange sparkle vs SE, but the PP can do bass and transients far better, and makes for a great all rounder.

My only real gripe is that DC heaters kill music (YMMV), so I use AC, and hum is still an issue, even in PP. But not enough to stir my lazy behind to get up and convert from 6B4G's to 2A3's.

 

[Omegaman]

A 2A3 SET Morikawa amp with Tango transformers is en route to me right now

I have to acquire 2A3 tubes for it

I believe my JBL 4343 speakers will handle the 3 watts okay

so excited

 

[Joe Roberts]

Keep in mind that any particular mentioned PP 2A3 amp does not fully represent ALL PP 2A3 amps, and so on for SE 2A3, SE300B, etc. Every amp is its own thing to a great extent.

That said, family resemblances do manifest. PP triode amps might be a little less psychedelic than SE triode amps, in general, but the added control will often be welcome.

The question arises whether SE300B would be better than PP2A3...same answer-- depends on the specific implementation. SE 300B amps run the gamut from sweet syrupy mud to crystal clear super punchy. Power supply and transformers have a lot to do with it.

SE NFB amps are wildly dependent on constructional details. Tube choice is only one determinant of flavor.

2A3 SEs sure can sound great but this is a low power setup, good sounding but low ass power. The PP amps I've used: Brook 10C and 12A, Peerless A100A DIY , and a couple 1930s style transformer coupled projects had a lot more drive than a single 2A3. All were pretty good amps in their own ways.

 

[soundmotor]

I have a 2A3 SET amp I love, but I have been looking at a 2A3 push-pull amp that looks pretty enticing. Does the 2A3 retain its magic in push-pull configuration? I am looking to drive some Tannoy 15" Golds, and I am thinking a 2A3 push-pull amp might be as nice or nicer than a 300b SET. Opinions?

Are you looking to build or buy it?

 

[Poultrygeist]

A 2A3 SET Morikawa amp with Tango transformers is en route to me right now

I have to acquire 2A3 tubes for it

I believe my JBL 4343 speakers will handle the 3 watts okay

so excited

94 dbs at 1 m and 102 dbs at 10 ft - you should be good to go

 

[larryderouin]

Poultry..........shouldn't that be the other way around db vs. distance????

 

[Poultrygeist]

Poultry..........shouldn't that be the other way around db vs. distance????

Specs from JBL

http://www.jblpro.com/pub/obsolete/4343b.pdf

 

[bean_counter]

Difference is the 4343B version uses ferrite instead of alnico drivers for the woofer and mid. Pretty sure the 1" and ring radiator are alnico in both. No real difference though most folks prefer alnico if they can get 'em.

I have the same 2231a woofer (actually the consumer 136a) as in the 4343, it's not all that efficient; may be a bit much for SE 2A3, depending on listening preferences. You might want to bi-amp.

 

[Arney]

Poultrygeist
Model 4343B Speakers
I gather that is around 35 watts of amp power to get 102 dB SPL at 10 feet?
Specs are damn amazing. 75 watts continuous sine wave.
I fried speakers with a sine wave test at only 10 watts

 

[Poultrygeist]

My 93 db BL horns powered by a 2a3 SET can play painfully loud.

 

[PakProtector]

Stick with a SET which unlike most push pull amps they don't employ negative feedback to gain higher power.

I believe you are operating under a few misconceptions about PP amps.
cheers,
Douglas