SET amp owners thread

[Ampexed]

I agree when you listen that loud then you need that kind of power. I never listen that loud.

That's fine and agree with you 100%. But I would only ask that you be open to the possibility that when you listen to music with significant low frequency information (bass drum, pipe organ, electronic) that you entertain the possibility that your low power SET might be introducing significant distortion. If the possibility that this is the case doesn't matter with you, that is fine!

I am above all, through my multi-decades journey as an electronics engineer, music composer and listener, an analog purist. I absolutely do not, and will not let anything intrude in that purity. If my experience showed something different than what I'm saying, I'd plainly state that!

 

[Ampexed]

If you read carefully, the low frequency range is where there is a lot of discrepancy between various curves, of which Fletcher Munson is the oldest. So, it is likely not as dramatic as these curves suggest, otherwise somewhat flat speakers would sound horribly thin. The B&K finding that a 1dB/octave downward slope gives the most natural sound, means that your bass will be 3-4 dB higher if done right but not 15 dB like F-M curves show.

I would ask that you do the simple experiment of placing an RMS voltmeter on the output of your power amplifier while playing the most demanding passages of low frequency content at healthy SPLs and do the calculation of watts. I think you will probably be surprised.

A frequency at 30Hz demands far more wattage to reproduce at the same subjective level as at 1kHz. Do the experiment yourself if you don't believe me.

 

[Kingrex]

Wrong thread

 

[DasguteOhr]

Example 300b Set Amp you get for every watt of output power 1% thd more. Unless you have oversized output transformer which can reduce this ratio. Still have at least 5%thd at 8 watt. which would be a great value for a 300b.
Exsample oversized 300b OPT 30lbs dampingfactor 12/at 8 ohms 6hz-46khz-3db

 

[morricab]

I would ask that you do the simple experiment of placing an RMS voltmeter on the output of your power amplifier while playing the most demanding passages of low frequency content at healthy SPLs and do the calculation of watts. I think you will probably be surprised.

A frequency at 30Hz demands far more wattage to reproduce at the same subjective level as at 1kHz. Do the experiment yourself if you don't believe me.

I can do that but I will simply circle back to what you consider to be a "healthy volume" (clearly you play well above 100 dB) is not at all what most people here are considering a healthy volume. I listen with peaks in the mid-90s dB with average levels in low 80s.

Again, I think there is a lot of discrepancy in the understanding of perception of loudness of low frequencies vs. higher frequencies. There is some controversy about those curves.

Anyway, I can say unequivocally that my 98dB speakers will play effortlessly with a 3.5 watt 2A3 amp up to levels that I find loud enough. My current amp has 20 watts but I didn't go to it for power reasons... If there is some additional distortion at high level peaks, so what? If it remains inaudible do i care? It has been demonstrated that the sensitivity to distortion decreases with increasing SPL. At your listening levels, you would be even less likely to hear a distortion increase.

I also have a fully active system that has a 99dB mid/bass in a TQWT cabinet and a compression driver tweeter (110dB) with active crossover. I now drive that tweeter with the 2A3 amp and I use an 18 watt SET on the mid/bass. There are no limitations in desirable volume.

 

[morricab]

Example 300b Set Amp you get for every watt of output power 1% thd more. Unless you have oversized output transformer which can reduce this ratio. Still have at least 5%thd at 8 watt. which would be a great value for a 300b.
Exsample oversized 300b OPT 30lbs dampingfactor 12/at 8 ohms 6hz-46khz-3dbView attachment 139171

That's a pretty big output trafo for a 300B...does it have good high frequency extension, which is usually the tradeoff for a big core?

 

[DasguteOhr]

That's a pretty big output trafo for a 300B...does it have good high frequency extension, which is usually the tradeoff for a big core?

Yes.i had write the false data of the OPT here is the correct datasheet.

 

[morricab]

Yes.i had write the false data of the OPT here is the correct datasheet.
View attachment 139174

Looks quite good!

 

[crosswind]

I had to read the whole thread in diyaudio to refresh my memory on this set of mods, it is some time ago...... and TL was a force on there for a number of years.

The 47 ohm resistor in the ht line is shunted, but by the WE / Ultrapath cap connecting the ht to the filament of the 300B. Apparently the "trick" to getting this right is the magic ratio of 3.2 between the WE / Ultrapath cap and the filament bypass cap. This approach has its advocates, and John Broskie ran a detailed analysis of it on Tubecad, concluding that if you want you use it, fitting it to 2 stages is better than one.

Ultrapath = Ultra Simple...Except that it's not

I would agree about the 300B snubber.

The grid choke will create an LF resonance with the small coupling capacitor, as discussed by TL in the diyaudio thread this can be several dB is size! The "fix" is to add the snubber circuit across the coupling cap, named DR.P (?) to try to counter this.

I have no doubt both mods are audible, and both have vocal advocates, it will be interesting to hear what @crosswind thinks of them once implemented and run in.

I think I might have missed this post even though it was tagged with my nick name.

I did, among other things to my amps, the DR.P/snubber modification and also the WE cap mod as described by T.L. using the appr. ratio of 3.2. In my case I used 15uF/50uF.

With the snubber in place I experienced more slam in the bass. It sounded more live-like and punchy with no degradation in resolution.

With the WE mod I got an increased sound stage where especially the mids benefited greatest.

 

[Atmasphere]

Obviously this depends on the music you listen to - if you listen to string quartets exclusively, none of this matters, but if you listen to digitally recorded orchestral music with significant low frequency content or electronic music with no limitation on low frequencies, then it matters a lot.

When I have said that SETs can't make bass, this is part of what I'm talking about. You can use a surprising amount of power getting the bass right even with speakers that are high efficiency. My speakers are 98dB and flat to 20Hz; I found that in my room (17' x 21') that 30 Watts/channel was not enough for the system to really be relaxed and effortless if there was heavy bass. Ampexed has the right idea by using a different amp for the bass and keeping the bass out of the SET driving the mids and highs. This vastly reduces distortion overall; IME distortion obscures detail so the result should be more musical- more relaxed, effortless mids and highs.

You could have the SET using smaller coupling caps so as to roll off well above 20Hz. In that way a powered sub could be used and the SET driven by a conventional preamp. If

Example 300b Set Amp you get for every watt of output power 1% thd more. Unless you have oversized output transformer which can reduce this ratio. Still have at least 5%thd at 8 watt. which would be a great value for a 300b.
Exsample oversized 300b OPT 30lbs dampingfactor 12/at 8 ohms 6hz-46khz-3db

Have you run this transformer in an amplifier yet? Does it express that bandwidth at full power (7-8 Watts)?

 

[DasguteOhr]

When I have said that SETs can't make bass, this is part of what I'm talking about. You can use a surprising amount of power getting the bass right even with speakers that are high efficiency. My speakers are 98dB and flat to 20Hz; I found that in my room (17' x 21') that 30 Watts/channel was not enough for the system to really be relaxed and effortless if there was heavy bass. Ampexed has the right idea by using a different amp for the bass and keeping the bass out of the SET driving the mids and highs. This vastly reduces distortion overall; IME distortion obscures detail so the result should be more musical- more relaxed, effortless mids and highs.

You could have the SET using smaller coupling caps so as to roll off well above 20Hz. In that way a powered sub could be used and the SET driven by a conventional preamp. If

Have you run this transformer in an amplifier yet? Does it express that bandwidth at full power (7-8 Watts)?

that is good idea i use under 90hz a class AB transistor amp with not so high damping factor. sounds very good with a variety of different tube amps.
the transformer has Pout ~14 watt/20hz with these specs a friend uses these transformers. the bass is excellent, does not seem soft or give the feeling that something is missing. Not yet measured is the manufacturer's specification.

 

[the sound of Tao]

How dare you trust your ears....SET is bad, bad BAD! isn't it obvious? Just look at those measurements...no don't listen that's heresy and might turn you away from the true path of Class D...

I’d definitely think SET ownership is dominated by people who largely trust in their listening experiences and weigh more heavily on their subjective listening evaluations than other parameters.

It’s easy to skew the issues of objective assessment like measurements for those not factoring in that the choice to go to SET requires specific system tailoring and that most successful SET based systems work with those paradigms. So the less ideal performance scenarios of pushing SET beyond its reasonable limits or using inappropriate speakers isn’t a concern for content SET owners but clearly more so for the measurement first dudes.

I’d also suggest most people who end up with a SET based system don’t start out with SET. It seems to me many people evolve to SET from more typical amplification. So they have good references for what they are hearing with SET versus SS or high powered push pull tubes.

Few people’s journeys start with SET and that’s because the output limitations and speaker requirements seem counter intuitive to a young newby out of a more is more culture. Big power and cubic capacity is a fantastic early attraction. Most of us who fall in love with SET likely come to SET after years of living with some pathway mix of solid state and or other push pull tube amps, maybe some even dallied with class D amps… I know there are those who also moved on from SET after trying it out. No particular topology is right for all listeners or for all circumstances.

So for the long lasting SET owner any constraint of its topology is obviously being outweighed by what are seen as SET strengths or virtues. I’m not sure we need to be educated continuously on well known pros and cons or convinced that what we hear isn’t the best choice for us out of all those that we could have made.

 

[LL21]

...I’d also suggest most people who end up with a SET based system don’t start out with SET. It seems to me many people evolve to SET from more typical amplification. So they have good references for what they are hearing with SET versus SS or high powered push pull tubes.

Few people’s journeys start with SET and that’s because the output limitations and speaker requirements seem counter intuitive to a young newby out of a more is more culture. Big power and cubic capacity is a fantastic early attraction. Most of us who fall in love with SET likely come to SET after years of living with some pathway mix of solid state and or other push pull tube amps, maybe some even dallied with class D amps… I know there are those who also moved on from SET after trying it out. No particular topology is right for all listeners or for all circumstances....

I think you also have to be really committed to venture down the relatively unfamiliar SET path. Far fewer dealer, displays and you have to understand sensitivity, loudspeaker matching to even get it work correctly. You cannot set up a Wilson Sasha or even some awkward bookshelves (the Magico Mini immediately comes to mind) with a 1 watt SET and hope for the best.

And since many low-wattage SETs are paired with horns, your commitment also probably relates to space. Full range horns start from BIG and get to MASSIVE. Even hybrids with big cones for bass are not that small.

Having finally heard a horn that intrigues me 2 years ago (the AG Trio G3), I could imagine how well that works with the Ongaku. But again, the floor area of the AG Trio G3 with its dual horns is nearly 5x that of the big Wilsons. just over 8 square feet vs 40 square feet or so.

 

[Ampexed]

I’m not sure we need to be educated continuously on well known pros and cons or convinced that what we hear isn’t the best choice out of all those we could have made.

While I don't doubt anybody's happiness with a SET setup, I would still hope that at least some of those who are 'satisfied' could be curious to know ways to take that SET sound to a higher level. What has been said about 'ease' at all sound levels is true - an SET gets obviously congested and constrained when being pushed too hard. The lack of those constraints really have to be heard to be appreciated. This isn't about measurements - it is just subjective and rather obvious audible shortcomings which take their toll on subjective 'realness'.

I would hope that people would not stick their heads in the sand if, as seems to be the general spirit here, there is a constant quest to make something which is already good into something which is great. BTW, I'm not selling anything or represent anybody but myself, so don't come after me for trying to sell you a product.

 

[Synaxis]

I respect all the posts on this thread and the different opinions.

It's interesting to see the tech talk about what SET does right and wrong.

At the end of the day, the SET's I have here bring me a level of musical bliss with my Tobian's I've never previously experienced in my system (I've had dozens of pieces come in and out).

Is it technically not ideal via measurements? I don't know.

Is there "better" amps? Probably.

Does it make me love what I have any less because it may technically have too much distortion? No way.

It's like my cine lenses - the ones that measure the best are boring and look lifeless to me. The ones that don't measure technically as ideal are the ones that produce images I can connect with. That's why I'm running 50 year old lenses on my camera.

 

[the sound of Tao]

I think you also have to be really committed to venture down the relatively unfamiliar SET path. Far fewer dealer, displays and you have to understand sensitivity, loudspeaker matching to even get it work correctly. You cannot set up a Wilson Sasha or even some awkward bookshelves (the Magico Mini immediately comes to mind) with a 1 watt SET and hope for the best.

And since many low-wattage SETs are paired with horns, your commitment also probably relates to space. Full range horns start from BIG and get to MASSIVE. Even hybrids with big cones for bass are not that small.

Having finally heard a horn that intrigues me 2 years ago (the AG Trio G3), I could imagine how well that works with the Ongaku. But again, the floor area of the AG Trio G3 with its dual horns is nearly 5x that of the big Wilsons. just over 8 square feet vs 40 square feet or so.

I’d love to hear a G3 with Kondo Ongaku and with the new panel subs Snbx is now using as well… think that’d be potentially very awesome.

It’s a giant move to go dynamic cones and box and high power amps to the other end of the spectrum and low power with horns… I often say to those who are keen to try that I don’t think SET horn is necessarily for everyone.

I have my own theories on how this fits with individual listening choices but for some it’s going to be a potentially revelatory shift and for others it might not be a good fit at all and a pause point rather than a destination and end up just a short term interest fling. Hard call without reasonable hours up listening to an equivalent setup and with plenty of the music you gravitate towards.

 

[LL21]

Everything you said makes sense to me. But having heard the AG Trio G3s...there was a lot to like, and I have been SF and Wilson back to back since 2004/5. And higher powered Class A SS for the majority of that time. But done right, it showed the prospect of real scale that other than the big Arrakis or the even bigger Genesis One, I had not heard from a big cone speaker before. Very very impressive and with a simple purity I found very impressive. More distilled down to the pure essence of the music than a mid-powered tube/Sonus Faber experience by a huge measure...while bringing the whole presentation to an unprecedented effortless scale level. And I am an enormous fan of the original SF Guarneris and Strads, both of which I owned for years.

 

[the sound of Tao]

Everything you said makes sense to me. But having heard the AG Trio G3s...there was a lot to like, and I have been SF and Wilson back to back since 2004/5. And higher powered Class A SS for the majority of that time. But done right, it showed the prospect of real scale that other than the big Arrakis or the even bigger Genesis One, I had not heard from a big cone speaker before. Very very impressive and with a simple purity I found very impressive. More distilled down to the pure essence of the music than a mid-powered tube/Sonus Faber experience by a huge measure...while bringing the whole presentation to an unprecedented effortless scale level. And I am an enormous fan of the original SF Guarneris and Strads, both of which I owned for years.

With large horns very much effortless scale is the big thing… along with real immediacy… I love big ribbon panels as well for they also have a potential less fettered sense of realism but the dynamic freedom that full scale horns can deliver is something else again for me.

With low powered SET coherence and realism with acoustic instruments and a good SET with the right drivers do both flow and fine resolution. My guide for really good SET is then when the music can also shift across into presenting more angular and intense performances as well. Ked often refers to flh being able to rock, the Avantgarde G3 Trio and Altec 817a dual flh both seem to be able manage there.

For EDM though I’m thinking full range ribbons with subs have a big head start… driving waves of Daft Punk edm on Maggie 20.7s with Wilson Benesch Torus subs can be a full on dance rave recall.

 

[the sound of Tao]

I do admit some are more resistant to learning than others. At what point did I say I don't appreciate SETs?? Please don't try to put words in my mouth.

Ralph I do genuinely feel that you see the SET negatives way more than you see any of the positives… in fairness it forms the consistent message and dominant approach that you tend to bring to this thread. Providing technical insights is great… it’s sharing technical subject matter expertise which is valuable but it’s just part of the story and we can learn different things from those who actually choose SET over other choices.

I think it’s great to have people bringing a range of technical knowledge and I’m a fan of reading the technical information that you and others here bring to the forum… its also reassuring that the strong technical bods don’t always agree with each other and that even with objective technical interpretation it’s not all black and white.

In terms of subjective listening skills snd gear preferences there are also others here that I resonate with and I really appreciate their subjective listening perspectives being shared here… objective technical background and subjective listening analysis can be two very different skills and I look to a different mix of people for their various objective and subjective perspectives.

While the thread is called SET owners thread it might serve anwareness even better if it were called SET owners… why do you live with SET amplification as your primary listening choice.

For me in a specific SET owners thread the real value might be looking to learn from the experiences and perspectives from those who choose to use SET for their music listening.

What is it about SET and in what ways don’t the measurements tell the whole story or reveal why some experienced listeners might choose it over amps that can in ways measure more impressively.

The technical constraints are well known among people experienced with SET, discussed often, perhaps not much really new there. Can we learn more about the nature of perception by not just dismissing other people’s choices or preferences as flawed.

 

[the sound of Tao]

While I don't doubt anybody's happiness with a SET setup, I would still hope that at least some of those who are 'satisfied' could be curious to know ways to take that SET sound to a higher level. What has been said about 'ease' at all sound levels is true - an SET gets obviously congested and constrained when being pushed too hard. The lack of those constraints really have to be heard to be appreciated. This isn't about measurements - it is just subjective and rather obvious audible shortcomings which take their toll on subjective 'realness'.

I would hope that people would not stick their heads in the sand if, as seems to be the general spirit here, there is a constant quest to make something which is already good into something which is great. BTW, I'm not selling anything or represent anybody but myself, so don't come after me for trying to sell you a product.

Genuinely all good with SET limitations but also maybe there’s not just one best way to approach set up with SET. There’s great examples here of very different approaches. Some people’s best setup strategies aren’t ideal for everyone’s preferences or applications.

The pros and cons of going simple with a single SET amp versus biamping and then all SET biamping or a mix and match approach to amp types based on frequency being amplified are maybe ultimately more about different priorities… maybe people more focussed on coherence might just set themselves up more simply while some chasing greater extremes and more extended linearity may find greater happiness in a four way with subs and multi amping with bandwidth specific amp choices. There’s plenty of valid approaches and I don’t think some choosing a different approach than the preferred pathways of others indicates necessarily that people are either refusing to learn or sticking their heads in the sand and I agree that mostly we are here looking to improve our approaches.

At some point you’ve got to make choices and it’s not all about win win necessarily. My objectives are simple and lead me to not wanting to go active or biamping which I’ve done both these in the past. I’m down to leaning into passive 2 way crossovers with one (SET) amp… but I completely get why others are into different gear approaches tho… that’s why we are here, to learn what works best for our own processes and priorities in our preferences… shaped by many things including the music that we love and the rooms that we are in and the gear that we most resonate with. It’s why it’s such an epic and worthy life long madness/pursuit.

I love the diversity of choices and strategies people use here.