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deciding on SET over push pull

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Posted on December 18, 2014 at 17:38:47
rws
Audiophile

Posts: 303
Location: Minnesota
Joined: September 7, 2004
 Hi,
I have been thinking about going SET, I believe my speakers are probably ok(Klipsch CF3).
What can I expect from SET that I was not getting from push-pull? Would I be correct in saying a special presence?








"Sometime I will have to give account of myself. How would the Father in heaven judge me if I followed others and not Him", Anton Bruckner

 

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RE: deciding on SET over push pull, posted on December 19, 2014 at 02:58:38
cpotl
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Location: Texas
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 You are potentially stirring up a hornets' nest, I think! I'm sure you will get a great many different answers.

My own view is that to the extent an SET amplifer gives a "special presence," which it may well do, it is because of its various transfer characteristics that represent "distortions" of the incoming audio signal. Amongst these, perhaps the main one is its significantly higher harmonic distortion, in comparison to most other amplifiers. This is predominantly second-harmonic distortion in an SET amplifier, which is said to be less objectionable (or maybe even pleasing) in comparison to higher-harmonic distortion. But, as with any nonlinear distortion, it will nevertheless mean that there will also be intermodulation distortion, which is never likely to be pleasing to the ear.

In any case, it seems clear that if an SET amplifier has a characteristic "sound," then this is because of distortion products that it injects into the audio signal. These may be considered desirable, at least by some people.

Chris

 

RE: deciding on SET over push pull, posted on December 19, 2014 at 04:33:16
Stuben
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Posts: 669
Location: Guber Ohio
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 I would maintain the PP amp and work into a less expensive SET amp to start. I personally, like both depending on the music I'm playing and mood.

I use my Pentode based PP as my work horse and bring out the expensive SET amp like someone would share a fine Scotch with friends...;>)

Yes, SET does have a special lower order harmonic distortion that tends to be euphoric with a nice sound stage presence. Well done PP can provides a Less "Fleshy" sound with a slightly better frequency extension and thump.

Have fun, you can have both...

Stuben

 

RE: deciding on SET over push pull, posted on December 19, 2014 at 04:51:55
vinnie2
Audiophile

Posts: 4481
Location: North Carolina
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 Find someone with a good one and go listen to it. There is a reason some many people have switched to using SE triode amps.

 

RE: deciding on SET over push pull, posted on December 19, 2014 at 05:01:03
lokie
Audiophile

Posts: 1990
Location: Georgia, USA
Joined: January 28, 2003
 That is such a personal choice that depends on ones own music, speakers, room, presentation, etc..

You have to chose on tradeoffs of both positives and negatives and what you can live with and without.

I have PP 2a3's and for now, couldn't be happier... but, I have been looking for a SET for a while now to have around as an alternative.

My suggestion is to pick up both SET and PP used and live with for a few months and then sell one.

 

Push-pull for you., posted on December 19, 2014 at 07:19:40
Chip647
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Posts: 2653
Location: The South
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 The impedance curve of the speaker is very important in the performance of tube amps. It is more than just efficiency. A SET requires a pretty flat impedance curve to sound its best. Your speakers are ported bass reflex speakers which will have a big hump in the impedance in bass frequencies. Without any feedback the power in these frequencies will be greatly affected. Push pull amps typically have more power and feedback which can negate some of the deleterious impacts of variable speaker impedance.

By the way, when you have proper speakers and SET amps operated within their power limits, they can have way less distortion than any other amplifier. The 300b is an extremely linear device. The "euphonic" distortion is from over driving and/or an impedance miss-match.

 

Not so sure, posted on December 19, 2014 at 08:09:46
SteveBrown
Audiophile

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Location: Portland, OR
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 I've used both SE and PP amps on the same bass reflex speakers and maybe mine are different than typical, but I don't find bass issues using SE at all. My speakers are similar to the 4Pi: JBL 2226 in a ported cabinet. Currently being driven by a 300b amp using an EL84 driver. I've also used PP KT88's, PP EL34's, etc. The 300b SE amp has been on the system for a long time now and the bass response is one of the reasons why.

My recomendation to the OP is to see if someone near by has a SET they are willing to bring to his house for an audition. I've done this many times for other audiophiles and made a number of good friends along the way. I'm in Portland, OR, and always happy to demo or help.

 

RE: deciding on SET over push pull, posted on December 19, 2014 at 08:28:24
GEO
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Contributor
  Since: September 9, 2000
 Its is easier to get great sound out of a SET vs a SE amp. If people put the same time and energy into a PP amp, you can get good results. A class A PP 2A3 or 50 can be nice sounding. I had a PP 47 with nickel interstages for phase splitting and it sounded great. Depending on what your needs are, you may find a PP amp more to your liking. I use a SE 801A.

 

Depends on the speakers for sure, posted on December 19, 2014 at 09:10:56
Chip647
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 There are synergies between speakers and amps. I could not find an impedance plot for his Klipsch. SETs have the most variability from sounding great to sounding like crap depending on speaker. Way more than the case with PP amps.

 

RE: deciding on SET over push pull, posted on December 19, 2014 at 09:27:16
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 Has anyone here answering looked up the specs on his speakers ? I think not !! They are 100 dB efficient.

YES, you are correct, IF the SE amp is designed well, properly built, you will get a "special presence" with a SET that a P-P amp will not provide, due to a P-P amp "processing the signal more so" than a SE amp does, due to phase inversion inherent in any P-P amp !!!

Now, the trick is to find a good SET !!!

Contact me via email, privately, and I will be happy to share my opinions on SE amp design, which is not the normal stuff people do !!

Jeff Medwin

 

RE: deciding on SET over push pull, posted on December 19, 2014 at 11:33:43
cpotl
Audiophile

Posts: 1002
Location: Texas
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 "...you will get a "special presence" with a SET that a P-P amp will not provide, due to a P-P amp "processing the signal more so" than a SE amp does, due to phase inversion inherent in any P-P amp !!!"

God help us...what new piece of nonsense is this???

Chris

 

RE: deciding on SET over push pull, posted on December 19, 2014 at 13:42:50
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 Its common knowledge and common sense, ask SET owners, who have had P-P amps before !!!

The music stays more intact, hence the resurgence in interest of SETs in recent decades.

Jeff Medwin

 

Jeff, have You heard a properly designed P/P DHT amp with phase done by a Xformer?, posted on December 19, 2014 at 14:13:26
Cleantimestream
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 !
The Mind has No Firewall~ U.S. Army War College.

 

RE: Jeff, have You heard a properly designed P/P DHT amp with phase done by a Xformer?, posted on December 19, 2014 at 14:23:11
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 Yes, and I have built it that way, back in 1998-2001, P-P 2A3s, demoed it to the New York City Audio Society / Club on Norelco 9710Ms.

Use of a transformer to split phase AFTER the input tube is one of my favorite and one of the the BEST compromise ways to do that inversion.

Does it equal a well-done SET, where no 180 degree inversion is needed ??

No way !!

The best sounding phase inversion is none at all, a good SET design.

Jeff Medwin

 

auditions, posted on December 19, 2014 at 14:29:11
rws
Audiophile

Posts: 303
Location: Minnesota
Joined: September 7, 2004
 Steve,
I would be more than willing to try a audition if someone were to be so kind and not an inconvenience for them I live in Minnesota and have not. located a retailer in the Mpls/St.Paul who carries Set's

Thanks Bob




"Sometime I will have to give account of myself. How would the Father in heaven judge me if I followed others and not Him", Anton Bruckner

 

My two cents, posted on December 19, 2014 at 17:18:06
Paul Joppa
Industry Professional

Posts: 7296
Location: Seattle, WA
Joined: April 23, 2001
 I get a special presence - some call it magical midrange - from pretty much any no-feedback SET. If it's not well done, it may hum, it may distort, it may have week bass or treble or both, it can even be boring or annoying - but I still find some magic in the midrange/presence region that's missing from push-pull - even if the P-P is no-feedback triodes.

Kind of a run-on sentence, sorry!

 

Use of A swamping resistor in Klipsch will level the playing field for a SET amp-nT, posted on December 19, 2014 at 17:41:10
Cleantimestream
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 !
The Mind has No Firewall~ U.S. Army War College.

 

RE: deciding on SET over push pull, posted on December 19, 2014 at 17:44:19
RC Daniel
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Posts: 1922
Location: Brisbane
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 >>> Has anyone here answering looked up the specs on his speakers ? I think not !! They are 100 dB efficient. <<<

Jeff, as you know, there is more to a speaker being ideal for SETs than mere sensitivity. Impedance, phase angles, driver Q and bass alignment. A SET might deliver some nice results with his speakers, but it would be hit or miss and I doubt that the "hit" would be particularly convincing.

Cheers.

"In the beginner's mind there are many possibilities, in the expert's mind there are few." Shunryo Suzuki

 

RE: deciding on SET over push pull, posted on December 19, 2014 at 19:57:54
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 Hi Daniel,

I would think, with a really good SET amp, and a commercial Klipsch speaker, the factors you mention will not be much of a problem at all.

Triodes drive well, into a variety of loads, and especially with a speaker having 100 dB sensitivity.

Can you explain to me why you are thinking it would not be too much of a "hit" ?? I do not really understand your concern. I wonder if I am over-simplifying this, or if you may be over-complicating the original poster's query?? Neither of us, by nature, seek to do the wrong thing !!

Jeff Medwin

 

The impedance.plot with Klipsch looks like the Andes... a.swamping.resistor will smooth.markedly-nT, posted on December 20, 2014 at 03:42:37
Cleantimestream
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 !
The Mind has No Firewall~ U.S. Army War College.

 

RE: deciding on SET over push pull, posted on December 20, 2014 at 04:14:54
sony6060
Audiophile

Posts: 1465
Location: USA
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 I find it easier to build a quality SET amp vs a PP amp of equal performance. The SET sounds more relaxed vs the higher dynamics of a carefully designed PP amp. Matching speakers to each amp is paramount.

At times I prefer the SET smooth & relaxed midrange and other times the more dynamic sound of a PP amp.

 

that.pretty much covers it for me-nt, posted on December 20, 2014 at 07:49:07
Cleantimestream
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 !
The Mind has No Firewall~ U.S. Army War College.

 

RE: deciding on SET over push pull, posted on December 20, 2014 at 07:56:49
GEO
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  Since: September 9, 2000
 My PP 47 sounded better than my SE 300B

 

It will also kill the power, posted on December 20, 2014 at 10:43:42
Chip647
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Posts: 2653
Location: The South
Joined: December 24, 2012

You are thinking of a Zobel network. They also have power losses.

 

RE: Push-pull for you., posted on December 20, 2014 at 11:58:48
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
 It would be an unusual generality to say not to use zero feedback SET amps with bass reflex speakers.

If the impedance dips low (below 6 Ohms or so for an 8 Ohm speaker), that can be an actual problem.

 

RE: deciding on SET over push pull, posted on December 20, 2014 at 12:01:33
Caucasian Blackplate
Industry Professional

Posts: 8313
Location: Seattle
Joined: June 18, 2004
 I had CF-4's for quite some time. I found that they worked quite well on just a couple of watts, and the bass response was sufficient to rattle pictures hanging on the walls.

Perhaps there is someone close by in Minnesota who can bring by a decent SET amp for you to try.

 

WHO has a SET amp in Minneapolis / St . Paul ??, posted on December 20, 2014 at 16:30:32
drlowmu
Manufacturer

Posts: 9730
Location: East of Kansas City
Joined: January 10, 2005
 See above, gentleman has Klipsch CF3 speakers, about 100 dB sensitivity.

Jeff Medwin

 

RE: deciding on SET over push pull, posted on December 20, 2014 at 17:54:49
rws
Audiophile

Posts: 303
Location: Minnesota
Joined: September 7, 2004
 I would assume the CF4's would be similar to the CF3's. The amps I was considering were Wright Audio Lolita, Decware Rachel, Coincident Dynamo, all EL34 based. I do have concerns about the impedance curve though.




"Sometime I will have to give account of myself. How would the Father in heaven judge me if I followed others and not Him", Anton Bruckner

 

RE: Push-pull for you., posted on December 20, 2014 at 17:59:03
rws
Audiophile

Posts: 303
Location: Minnesota
Joined: September 7, 2004
 If the impedance curve is in fact not ideal for the SET amp, would the push pull deal with that impedance curve better?




"Sometime I will have to give account of myself. How would the Father in heaven judge me if I followed others and not Him", Anton Bruckner

 

image of the plot, posted on December 20, 2014 at 18:12:59
rws
Audiophile

Posts: 303
Location: Minnesota
Joined: September 7, 2004
 Hello Cleantimestream,
If you would be able to share a image of the impedance plot I would greatly appreciate that, I could not find one.

Bob




"Sometime I will have to give account of myself. How would the Father in heaven judge me if I followed others and not Him", Anton Bruckner

 

RE: deciding on SET over push pull, posted on December 20, 2014 at 23:13:36
RC Daniel
Audiophile

Posts: 1922
Location: Brisbane
Joined: November 3, 2002
 Sorry Jeff, I might have unintentionally implied that you might have sought to do the wrong thing. Apols.

I don't think I am over-complicating the OP's question. To clarify:

A driver in a bass alignment designed to be driven by an essentially zero output impedance amp may sound okay with a SET amp, but it is not ideal. Add the 2 - 3 Ohms SET output impedance to the mix and things change... the alignment transitions to under-damped and becomes relatively indistinct and lacking impact, even if giving the impression, perhaps, of increased weight... As I said, it might sound okay.

Cheers.

"In the beginner's mind there are many possibilities, in the expert's mind there are few." Shunryo Suzuki

 

RE: deciding on SET over push pull, posted on December 21, 2014 at 14:57:24
Caucasian Blackplate
Industry Professional

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Location: Seattle
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 An EL-34 based amp is not exactly an SET.

 

RE: deciding on SET over push pull, posted on December 21, 2014 at 15:36:32
rws
Audiophile

Posts: 303
Location: Minnesota
Joined: September 7, 2004
 I realize that but the EL34's a wired in the triode configuration. I have seen the Decware Rachel and Coincident Dynamo talked about here.




"Sometime I will have to give account of myself. How would the Father in heaven judge me if I followed others and not Him", Anton Bruckner

 

RE: deciding on SET over push pull, posted on December 22, 2014 at 13:31:40
Frihed89
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Posts: 15703
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 The most important difference may be the use of a DHT vs. an IDHT

 

RE: It will also kill the power, posted on December 23, 2014 at 03:29:09
Cleantimestream
Audiophile

Posts: 7551
Location: Kentucky
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 Incorrect Chip
There is NO load on the circuit. Indeed it allows for more power

Think it through.
The Mind has No Firewall~ U.S. Army War College.

 

RE: It will also kill the power, posted on December 23, 2014 at 14:58:16
Tre'
Industry Professional

Posts: 17306
Location: So. Cal.
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 If the swamping resistor presents no load how does it cause a change?

Can you show a diagram?

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

Sure can..., posted on December 23, 2014 at 15:59:10
Cleantimestream
Audiophile

Posts: 7551
Location: Kentucky
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 Al Klappenberger explains more succinctly than I.


Speaker design is far more complicated than the simplest building block known as an amplifier. Scroll down for pdf file that contains the full explanation.

To the idiots who insist that the "swamping resistor" used in ALK network circuits to set the midrange level absorb power reducing the efficiency of the speaker, consider this: A loudspeaker's efficiency is defined as the loudness in dB sound pressure level at 1 meter from the speaker when 1W of power is applied. This is usually done with 2.8V applied. The midrange is always attenuated to match the woofer, which determines the efficiency. No matter if the midrange is attenuated with an L-pad, a transformer alone or a transformer and swamping resistor the efficiency will measure the same with 2.8V applied! You have intentionally adjusted it to be so by attenuating the midrange to match the woofer! A swamping resistor or a resistive L-pad absorbs the extra efficiency of the midrange that you don't need. With a transformer alone, as with the Klipsch network designs, the impedance seen by the amp rises to reduce current, and therefor the power, drawn form the amp instead. This is undesirable because it does bad things to your amp and to the filters in the network. Energy wisely used for a specific purpose, in this case, to give your amplifier a constant load, is NOT wasted power! The swamping resistor is a win-win situation in all respects.

A paper explaining the theory behind the use of an autotransformer and swamping resistor to allow adjustable attenuation of drivers in a crossover network.

(by Al Klappenberger}


The Mind has No Firewall~ U.S. Army War College.

 

RE: Sure can..., posted on December 23, 2014 at 16:37:50
Tre'
Industry Professional

Posts: 17306
Location: So. Cal.
Joined: February 9, 2002
 I had already read that.

But here's the context. Al is talking about a swamping resistor in the midrange section of the crossover.

"The midrange is always attenuated to match the woofer, which determines the efficiency."

I thought we were talking about a swamping resistor for the whole speaker system.

My bad.

edit, BTW, In terms of the above example with a swamping resistor on the midrange, the resistor does cause a load but only in the midrange band pass. It does rob power, but in this example it's OK because the midrange needs to be lowered in amplitude to match the efficiency of the woofer.

Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"

 

RE: Sure can..., posted on December 23, 2014 at 16:41:43
Garg0yle
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 I thought they were too.
△This message will self destruct in 10 seconds△

 

RE: image of the plot, posted on December 23, 2014 at 16:53:07
Cleantimestream
Audiophile

Posts: 7551
Location: Kentucky
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 neither could I.

Klipsch has always used transformers to match compression drivers with dynamic woofers, {The Khorn and Jubilee are exceptions} consequently the backlash is a rapidly rising impedance in proportion to the attenuation of the horn. The two-way design of the the CF-3 {I thought the CF4 was one of Klipsch's better designs... Roy Delgado} will not incur as steep a penalty secondary to the efficiency not being near as high as the Heritage series.
The Mind has No Firewall~ U.S. Army War College.

 

thanks, posted on December 23, 2014 at 17:51:57
rws
Audiophile

Posts: 303
Location: Minnesota
Joined: September 7, 2004
 Thank you very much for the reply. As you can see I am trying to decide if I should try SET with these speakers(I realize the Decware and Wright Audio El34's are a bit different). They are quite reasonably priced and I am intrigued by the SETs. If I found I need more power I am interested in A push-pull or the Rogue Sphinx which I have read good reports about and there is a dealer near me for audition(which would be helpful).

Thanks Bob




"Sometime I will have to give account of myself. How would the Father in heaven judge me if I followed others and not Him", Anton Bruckner

 

RE: thanks, posted on December 26, 2014 at 09:16:07
Cleantimestream
Audiophile

Posts: 7551
Location: Kentucky
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 The chief factor now would be how large your room is. How loud you play is, of course another major factor. P/P IN class A can sound excellent. Triode wired 6L6 is an excellent alternative.
The Mind has No Firewall~ U.S. Army War College.

 

RE: thanks, posted on December 26, 2014 at 13:42:50
rws
Audiophile

Posts: 303
Location: Minnesota
Joined: September 7, 2004
 My room is approx 12'x 17', and I do not listen real loud, but I do listen to some large orchestral. So I am concerned about SET handling the large orchestral and also having well defined tight bass. When I tried a older Yamaha main amp with a tube pre amp the bass was good (punch?), and the mids were ok. My speakers are very efficient that's why I thought SET




"Sometime I will have to give account of myself. How would the Father in heaven judge me if I followed others and not Him", Anton Bruckner

 

+1 (nt), posted on December 26, 2014 at 21:48:08
Triode_Kingdom
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Location: Central Texas
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 nada aqui

 

RE: deciding on SET over push pull, posted on December 27, 2014 at 05:07:44
JBryan
Audiophile

Posts: 148
Location: Baltimore
Joined: September 9, 2002
 I appreciate SET amps for their fast transients and the 'presence' they bring to the music. The Epic series is actually very nice sounding gear though not the 'signature' Klipsch sound many know. I've had the CF-4 and still have a pr each of CF-3 and 2 and have tried several amps on them, including SET. My take was that the Epics handled 8+ watts pretty well with all but the CF-4's being able to play at comfortable levels without noticeable distortion.

Depending on your room and SPL preferences, the CF-4 would do OK with a 300b SET but I'm not a big fan of amps based on that tube though I've only had a handful over the years. My preference is for 45-based amps (and VT-25's) but they are way too underpowered for the Epics. The lowest wattage amps that I felt were suitable were a 6c33-based amp I had built for me and a Brenneman Cavalier SEP amp. Both amps put out @10watts and the Cavalier had the best 'synergy' - it really sounded good even at higher volumes (90+ SPL) with the bottom end being particularly impressive.

Of course, the Epic series woofers will benefit from more watts and unlike Klipsch's heritage line, they actually sound good with clean SS and even some digital amps (HERESY!, I know).

 

RE: deciding on SET over push pull, posted on December 27, 2014 at 07:59:40
rws
Audiophile

Posts: 303
Location: Minnesota
Joined: September 7, 2004
 Hi JBryan, thanks for the reply. The amps I a considering now are(all integrated)Wright Audio Lolita, Decware Rachel, Coincident Dynamo(all EL34 based). These are all around 8wpc.
Also the Rogue Sphinx(hybrid) because I have a dealer in my area and I tried my Yamaha solid state with a tube pre amp and it was not bad, and the Sphinx gets good reviews.

Thanks Bob




"Sometime I will have to give account of myself. How would the Father in heaven judge me if I followed others and not Him", Anton Bruckner

 

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