What are the advantages/disadvantages of different amp topologies?

[morricab]

So, are you saying PP and OTL put out odd order harmonics so don’t sound natural, and SETs put out even order from 2nd down to noise floor (no 3rd order?) and thus sound more natural? Adding, that core saturation in SETs ( even the best? ) down around 50 Hz is the reason SETs sound lush?

yes the First Watt F3 used JFETs, don’t think Mosfet’s however?

Not quite. OTL and PP amps (both SS and tube) make predominantly odd harmonics. SETs make all even and odd but in a decreasing level with increasing harmonic order. Core saturation is one reason for “tubey” sound…probably not the only one.

Simplified schematic in the F3manual shows a JFeT and MOSFET…not sure how exactly it works.

 

[andromedaaudio]

Ideally , take advantage of both .
A second hand pair of ARC REF 160 M can be found for 16 - 17 K secondhand .
A nice CH power amp can be found for 30 K so for 50 K all the complaining / whining can be a thing of the past .

.... just enjoy

 

[Republicoftexas69]

Ideally , take advantage of both .
A second hand pair of ARC REF 160 M can be found for 16 - 17 K secondhand .
A nice CH power amp can be found for 30 K so for 50 K all the complaining / whining can be a thing of the past .

.... just enjoy

Completely agree.

 

[morricab]

Don't have a dog in this hunt, and not getting into any of the technical stuff. But it is interesting to compare how the sonic attributes of SET amps tend to be described in language compared to everything else. FYI - two reviews of the same SET amp, from two different reviewers, 18 years apart:

Review: Viva Solista Integrated Amplifier - Twittering Machines

Michael Lavorgna's Twittering Machines: HiFi with a twist

twitteringmachines.com

https://www.stereophile.com/artdudleylistening/1105listening/index.html

Certainly sounds promising…but look at the price hike!

 

[morricab]

Not at all! That really isn't a benefit of SETs:

FWIW PP really doesn't have that problem unless the amp isn't biased properly or its malfunctioning. It literally isn't a thing and hasn't been for my entire adult life.

I remember when I was working in the Allied Radio Shack service department I'd see some cheaper solid state amps come in where it was obvious the bias had not been set up properly from the factory. There would be a little notch distortion and it was really easy to hear. So I would set the bias (most solid state amps of the 70s and 80s have both a bias and DC Offset control in the circuit) to get rid on the notch. At first I did it on the oscilloscope but it was so audible I found I could do just as well setting it by ear.

Class D amps are immune to that problem if they have an output filter for the switching frequency and all of them I've ever seen do. Its possible to do a Class D without the filter using some fancy servo techniques but those techniques open the design to a crossover issue so no-one uses it.

So its not something that SETs bring to the table that other amps don't.

There are plenty of SS amp measurements showing crossover distortion…some very recent ones.

 

[morricab]

So, are you saying PP and OTL put out odd order harmonics so don’t sound natural, and SETs put out even order from 2nd down to noise floor (no 3rd order?) and thus sound more natural? Adding, that core saturation in SETs ( even the best? ) down around 50 Hz is the reason SETs sound lush?

yes the First Watt F3 used JFETs, don’t think Mosfet’s however?

Go look at the OTL measurements I posted and you will see for yourself how they are all somewhat similar…despite being different designs.

 

[acousticsguru]

Go look at the OTL measurements I posted and you will see for yourself how they are all somewhat similar…despite being different designs.

Indeed, if there are more recent OTL designs that differ from this behavior, I'd love to see measurements - I realize I'm repeating myself…

Greetings from Switzerland, David.

 

[acousticsguru]

You were the one to make the generalized comment about class D. I am not the one demeaning the topology. I am very content with both my tube and GaN amplification.

I don't much care what I'm listening to as long as it sounds great. Thus far, the best I've heard in GaN amplification were different AGD models (not sure what Boenicke's uses in his Class D), so I'll postpone my verdict except to say that so far I'm still hearing a common "theme" in Class D that has nothing to do with the fact that the most recent do sound "warm" as has been suggested above (I don't think of that term as denoting greater or lesser artificiality, however pleasant one may find "warm" sounding audio, to me audio may simultaneously sound nasty and warm, or not nasty etc., it's just a characteristic, non-exclusive).

Greetings from Switzerland, David.

 

[Republicoftexas69]

I don't much care what I'm listening to as long as it sounds great. Thus far, the best I've heard in GaN amplification were different AGD models (not sure what Boenicke's uses in his Class D), so I'll postpone my verdict except to say that so far I'm still hearing a common "theme" in Class D that has nothing to do with the fact that the most recent do sound "warm" as has been suggested above (I don't think of that term as denoting greater or lesser artificiality, however pleasant one may find "warm" sounding audio, to me audio may simultaneously sound nasty and warm, or not nasty etc., it's just a characteristic, non-exclusive).

Greetings from Switzerland, David.

I agree to a point. I am quite smitten with my GN PA-10's v2. Have you listened to them or the Atma-Sphere GaN. I just do not care for generalized comments about any topology without qualification. When I asked the response was quite rude. That is okay that is what the ignore feature is for. I put more stock in real industry experts like Ralph as opposed to subjective opinions from a distributor.

 

[acousticsguru]

I agree to a point. I am quite smitten with my GN PA-10's v2. Have you listened to them or the Atma-Sphere GaN. I just do not care for generalized comments about any topology without qualification. When I asked the response was quite rude. That is okay that is what the ignore feature is for. I put more stock in real industry experts like Ralph as opposed to subjective opinions from a distributor.

Goldnote, yes. Atmasphere, not that I remember, no. I find it hard to explain, but the common theme I'm hearing is a "sculpting" of sound (nothing to do with how fast or how slow), and I cannot say it's true for all Class D that is out there, just what I've heard. This sense of perceiving sound as if it's being molded sounds artificial to me, even if in degrees, ranging from pleasant to smoothed over and weird/annoying. Needless to say, much depends on the type of music being played back. I'm reminded of a joke I once made in a classical music review that went viral years ago, that to my ears Herbert von Karajan made everything sound like Bruckner with the exception of Bruckner.

Greetings from Switzerland, David.

 

[acousticsguru]

Goldnote, yes. Atmasphere, not that I remember, no. I find it hard to explain, but the common theme I'm hearing is a "sculpting" of sound (nothing to do with how fast or how slow), and I cannot say it's true for all Class D that is out there, just what I've heard. This sense of perceiving sound as if it's being molded sounds artificial to me, even if in degrees, ranging from pleasant to smoothed over and weird/annoying. Needless to say, much depends on the type of music being played back. I'm reminded of a joke I once made in a classical music review that went viral years ago, that to my ears Herbert von Karajan made everything sound like Bruckner with the exception of Bruckner.

Greetings from Switzerland, David.

I'm hearing the exact same in some types of DACs, by the way, e.g. Playback Designs. And I understand full well why people like them: there's not a rough edge to be heard anywhere. Doesn't sound "right" (like live music) to me, though.

(Edit: should probably add "unamplified live music" such as classical, or "unplugged" jazz etc.)

Greetings from Switzerland, David.

 

[Rensselaer]

So how do we get that “right” sound, as close to unamplified acoustic instruments as possible?

If Class of amplification isn’t, is it down to limiting capacitance, simplifying design, using interstage transformers, managing voltage regulation with valves, pure silver or copper wire, hollow state over solid state, NOS valves from the classic producers over new valves from China or Russia? So far, I have not been able to discern any absolutes here.

 

[morricab]

So how do we get that “right” sound, as close to unamplified acoustic instruments as possible?

If Class of amplification isn’t, is it down to limiting capacitance, simplifying design, using interstage transformers, managing voltage regulation with valves, pure silver or copper wire, hollow state over solid state, NOS valves from the classic producers over new valves from China or Russia? So far, I have not been able to discern any absolutes here.

Topology is important but so is the execution. I don't know that there is a hard and fast rule on the execution side, but from the psychoacoustic perspective, and the realization that there is no zero distortion amplification, then, in the here and now a single ended topology using triodes or triode/FET combinations is likely the best topology as it follows more closely a natural harmonic pattern.

The execution should be that it maintains as close as possible the ideal harmonic pattern at all output levels. This should be looked at in context with the loudspeaker sensitivity and load as the right harmonic pattern is also SPL dependent.

I have heard amps with SS elements (KR Audio, Silvercore/Silbatone, Ypsilon, Aries Cerat, NAT, Pathos), which were quite natural sounding...just not a single amp yet that was all SS that sounded natural...or Class D.

Interestingly, they all do something different:
KR Audio has input and driver as single SS elements and the output is tube (reverse hybrid SET)
Silvercore and Silbatone have neo hybrids where the input is tube and the output is tube/FET hybrid element
Aries Cerat is a single hybrid element (tube/FET)
NAT is also a single element hybrid
Ypsilon is a single ended hybrid with tube input/driver and FET output (NAT made one like this too called Symbiosis SE)
Pathos is kind of similar to this but they have their own patented hybrid single ended circuit.

They are all single ended though and all sound quite natural...like a good SET...perhaps even better than most SETs.

 

[Rensselaer]

Topology is important but so is the execution. I don't know that there is a hard and fast rule on the execution side, but from the psychoacoustic perspective, and the realization that there is no zero distortion amplification, then, in the here and now a single ended topology using triodes or triode/FET combinations is likely the best topology as it follows more closely a natural harmonic pattern.

The execution should be that it maintains as close as possible the ideal harmonic pattern at all output levels. This should be looked at in context with the loudspeaker sensitivity and load as the right harmonic pattern is also SPL dependent.

I have heard amps with SS elements (KR Audio, Silvercore/Silbatone, Ypsilon, Aries Cerat, NAT, Pathos), which were quite natural sounding...just not a single amp yet that was all SS that sounded natural...or Class D.

Interestingly, they all do something different:
KR Audio has input and driver as single SS elements and the output is tube (reverse hybrid SET)
Silvercore and Silbatone have neo hybrids where the input is tube and the output is tube/FET hybrid element
Aries Cerat is a single hybrid element (tube/FET)
NAT is also a single element hybrid
Ypsilon is a single ended hybrid with tube input/driver and FET output (NAT made one like this too called Symbiosis SE)
Pathos is kind of similar to this but they have their own patented hybrid single ended circuit.

They are all single ended though and all sound quite natural...like a good SET...perhaps even better than most SETs.

So a “single ended” hybrid system using valves and Mosfets is the design topology most likely to provide the “right” sound, a realism likely to meet or beat good SET’s (Wavac, Kondo, Yamamoto, Shindo etc.) then?

 

[morricab]

So a “single ended” hybrid system using valves and Mosfets is the design topology most likely to provide the “right” sound, a realism likely to meet or beat good SET’s (Wavac, Kondo, Yamamoto, Shindo etc.) then?

Again, possibly maybe.

 

[bonzo75]

The Silvercore neohybrid amp is a different one. His usual 833c is not a neohybrid, he also has an EIMAC based 304TL. It might have an inpu FET but his neohybrid designated amp is a totally different one/

The Ypsilon hybrid is quite an average amp, Luxman m800u was quite better than it in a direct compare on Vivids.

 

[morricab]

The Silvercore neohybrid amp is a different one. His usual 833c is not a neohybrid, he also has an EIMAC based 304TL. It might have an inpu FET but his neohybrid designated amp is a totally different one/

The Ypsilon hybrid is quite an average amp, Luxman m800u was quite better than it in a direct compare on Vivids.

I was not saying Silvercore only made the neohybrid…I have a 2A3 amp from them!
I would not call Ypsilon’s SET 100 ultimate an average amp. It is one of only a very few single ended hybrids to hit the market.

 

[bonzo75]

I was not saying Silvercore only made the neohybrid…I have a 2A3 amp from them!
I would not call Ypsilon’s SET 100 ultimate an average amp. It is one of only a very few single ended hybrids to hit the market.

Not the SET 100, I was referring to their hybrid amp

 

[Rensselaer]

“single ended“, I am assuming, meaning the signal is simply amplified without adding complicated (and sound worsening) distortion reduction or power increasing circuitry as found in some OTL and Push Pull amps (respectively).

The distortion, allegedly caused by transformer saturation, I read is also reduced/eliminated by building the transformers of the correct materials and size, carefully. High power triodes are few and far between, operating voltages lethal, so perhaps we should concentrate our attention on perfecting the higher efficiency speaker so that we can get by with low parts count flea-powered SET amplifiers (like what used to be norm).

 

[morricab]

Not the SET 100, I was referring to their hybrid amp

Set 100 is a hybrid amp