Is there a Solid State amp that can satisfy a SET guy?

Vinnie knows what music sounds like and is a very nice guy, I was very impressed by his early battery powered small amps. I bet his new integrated is excellent, Think there is an option of tube choice. If you can use a 300B, I would highly recommend getting Takasukis. Parts Connection in Canada has them for $1400.
They are the next best to old WEs.

Pass XA25..  You will want to open it up and check for tubes inside.. 

Dartzeel. Built to last forever so given this look for used units. The CTH 8550 integrated amp is a truly great product but it very much needs to be used single ended if you want the magic. They have a VERY short existence on the used market. Try Chambers Audio for a used unit. The alternative would be an NHB-108b amp but the integrated is so close. Also you wouldn’t be buying a boat anchor. I no longer have one but was foolish to sell mine(CTH 8550).

Pass XA25.. You will want to open it up and check for tubes inside..

Ah yeah??? unusually tight, uncoloured and extended sounding tubes yes.
Other amps but low power and gain would be Nelson Pass’s Aleph’s, which think all models are single ended, but solid state, and are room heaters also just like tube SE's.

Cheers George

The more I listen to my Bakoon HPA-01 the more I love it.
This is THE SS amp that can satisfy a SET guy or anyone.
It leaves me imagining just how spectacular a higher powered Bakoon would sound in my main rig. Meanwhile I am enjoying it with my headphones!

Hi mglik

If you have a Pass Labs dealer near you and after your new speakers are fully broken in, see if you can try (in your own system) an XA30.8. Their class a/b amps are very good but their class a amps are where their magic is. This amp has surprising drive capabilities but more importantly always sounds great.  It is extremely musical. This amp sounds like a good tube amp in the midrange but also gives you all the benefits of a solid state amp such as extended, controlled bass with plenty of slam. The high frequencies are both extended and smooth as well. Their reliability is legendary. I’m currently (no pun intended) enjoying it and my speakers are 83db efficient, don’t let the 30 watt rating fool you. I’ve had mine for over five years and have used it with several different types of speaker (both planar magnetic & dynamic box speakers) and it always sounds great. Good luck.

Scot

Many speak highly of Nelson’s work. Whitecamaros seems to prefer the 250.8 above all. I surely have heard of the prowess of the 30.8.
I have a First Watt M2 which sounds quite SS. Ralph has developed a Class D amp which he says is very similar sounding to his OTLs.
I hope to eventually get to test a prototype.
The Bakoon does not sound like tubes but it recreates pace and structure in a way that holds music together in an unusual and addictive manner. And it produces detail that other amps, tube or SS blur. But ultimately, the Atmas produce a tone that is just natural and beyond any I have heard.

Any chance we can get an update on this thread? Curious how things/where things have ended up...

Well it’s been several months. Last time around I was touting the virtues of the First Watt SIT-3. I still do. It’s one of the most satisfying, listenable amps I’ve ever heard. 
Since then, I was able to audition the AGD Audion monoblocks in my system. Game changer. I would imagine that these could satisfy SET-loving listeners out there. Not everyone of course but it’s the closest I’ve come thus far and ended building a system around them. These are beautiful sounding amps…Perhaps other AGD users might chime in as well…

I believe the OP has the AGD Audion's now. I also own the AGD Audion's fantastic amps and i was a SET guy.

Those AGD amps look crazy interesting.  Never heard of them.  I'm going to have to investigate.  They actually look like something new!

I bought a Pass INT-25 a few months ago and am extremely satisfied.  The only "downside" so to speak is that it does take a while to sound it's best.   A good hour in my case.  Its as good as the reviews I read prior to purchasing with Harbeth M30.1's.

Is there a Solid State amp that can satisfy a SET guy?

Yes, the Nelson Pass single ended transistor amps, think they’re called Aleph’s"



If you have the patience, here what he says about them

Single Ended Class A Nelson Pass Introduction

Single-Ended Class A amplifiers have certainly hit it big in the four years since we began testing the first Aleph 0. So is this just another audio fad, or is there something fundamental about this kind of design, justifying a revival of the old approaches to amplification?

When I started designing amplifiers twenty-five years ago, solid state amplifiers had just achieved a firm grasp on the market. Power and harmonic distortion numbers were the important thing, and the largest audio magazine said that amplifiers with the same specs sounded the same.

We have heard Triodes, Pentodes, Bipolar, VFET, Mosfet, TFET valves, IGBT, Hybrids, THD distortion, IM distortion, TIM distortion, phase distortion, quantization, feedback, nested feedback, no feedback, feed forward, Stasis, harmonic time alignment, high slew, Class AB, Class A, Pure Class A, Class AA, Class A/AB, Class D, Class H, Constant bias, dynamic bias, optical bias, Real Life Bias, Sustained Plateau Bias, big supplies, smart supplies, regulated supplies, separate supplies, switching supplies, dynamic headroom, high current, balanced inputs and balanced outputs.

I have to admit that I’m responsible for a couple of these myself.

Apart from digitally recorded source material though, things have not changed very much. Solid state amplifiers still dominate the market, the largest audio magazine still doesn’t hear the difference, and many audiophiles are still hanging on to their tubes. Leaving aside the examples of marketing hype, we have a large number of attempts to improve the sound of amplifiers, each attempting to address a hypothesized flaw in the performance.

There has been a failure in the attempt to use specifications to characterize the subtleties of sonic performance. Amplifiers with similar measurements are not equal, and products with higher power, wider bandwidth, and lower distortion do not necessarily sound better. Historically, that amplifier offering the most power, or the lowest IM distortion, or the lowest THD, or the highest slew rate, or the lowest noise, has not become a classic or even been more than a modest success. For a long time there has been faith in the technical community that eventually some objective analysis would reconcile critical listener’s subjective experience with laboratory measurement. Perhaps this will occur, but in the meantime, audiophiles largely reject bench specifications as an indicator of audio quality. This is appropriate. Appreciation of audio is a completely subjective human experience. We should no more let numbers define audio quality than we would let chemical analysis be the arbiter of fine wines. Measurements can provide a measure of insight, but are no substitute for human judgment.

Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not.

If you continue to increase the bias current far beyond the operating point, it appears that improvements are made with bias currents which are much greater than the signal level. Typically the levels involved in most critical listening are only a few watts, but an amplifier biased for ten times that amount will generally sound better than one biased for the few watts.

For this reason, designs which operate in what has been referred to as "pure" Class A are preferred because their bias currents are much larger than the signal most of the time. As mentioned, preamp gain stages and the front ends of power amplifiers are routinely single-ended "pure" Class A, and because the signal levels are at small fractions of a watt, the efficiency of the circuit is not important.

The "purity" of Class A designs has been at issue in the last few years, with "pure" Class A being loosely defined as an idling heat dissipation of more than twice the maximum amplifier output. For a 100 watt amplifier, this would be 200 watts out of the wall on a constant basis. Designs which vary the bias against the musical signal will generally have bias currents at or below the signal level. This is certainly an improvement from the viewpoint of energy efficiency, but the sound reflects the lesser bias point.

Given the assumption that every process that we perform on the signal will be heard, the finest amplifiers must employ those processes which are most natural.

There is one element in the chain which we cannot alter or improve upon, and that is the air. Air defines sound, and serves as a natural benchmark.

Virtually all the amplifiers on the market are based on a push-pull symmetry model. The push-pull symmetry topology has no particular basis in nature.

Is it valid to use air’s characteristic as a model for designing an amplifier? If you accept that all processing leaves its signature on the music, the answer is yes.

One of the most interesting characteristics of air is its single-ended nature. Sound traveling through air is the result of the gas equation:

PV1.4 = 1.26 X 104

where P is pressure and V is volume. The small nonlinearity which is the result of air’s characteristic is not generally judged to be significant at normal sound levels, and is comparable to the distortion numbers of fine amplifiers. This distortion generally only becomes a concern in the throats of horns, where the intense pressure levels are many times those at the mouth, and where the harmonic component can reach several per cent.

We can push on air and raise the pressure an arbitrary amount, but we cannot pull on it. We can only let it relax and fill a space as it will, and the pressure will never go below "0". As we push on air, the increase in pressure is greater than the corresponding decrease when we allow air to expand. This means that for a given motion of a diaphragm acting on

rated output power.

Single-ended operation is not new. It is routinely found in the low level circuitry of the finest preamplifying stages and in the front end circuits of the finest power amplifiers. The first tube power amplifiers were singleended circuits using a single tube driving the primary of a transformer.

In 1977 I designed and published in Audio Magazine a single-ended Class A amplifier using bipolar followers biased by a constant current source. A considerable number of amateurs have built the device, rated at 20 watts output, and many have commented on its unique sonic signature. It is one of the very few examples of a solid state singleended output stage available.

Single-ended Class A operation is less efficient than push-pull. Singleended amplifiers tend to be bigger and more expensive than push-pull, but they have a more natural transfer curve.

A very important consideration in attempting to create an amplifier with a natural characteristic is the selection of the gain devices. A singleended Class A topology is appropriate, and we want a characteristic where the positive amplitude is very, very slightly greater than the negative. For a current gain device, that would mean gain which smoothly increases with current, and for a tube or field effect device a transconductance which smoothly increases with current.

Triodes and Mosfets share a useful characteristic: their transconductance tends to increase with current. Bipolar power devices have a slight gain increase until they hit about an amp or so, and then they decline at higher currents. In general the use of bipolar in a singleended circuit is a poor fit.

Another performance advantage shared by Tubes and Fets is the high performance they deliver in simple Class A circuits. Bipolar designs on the market have between four and seven gain stages associated with the signal path, but with tubes and Mosfets good objective specifications are achievable with only 2 or 3 gain devices in the signal path.

Yet a third advantage tubes and Mosfets have over bipolar devices is their greater reliability at higher temperatures. Single-ended power amplifiers dissipate comparatively high wattages and run hot.

In a decision between Triodes and Mosfets, the Mosfet’s advantage is in naturally operating at the voltages and currents we want to deliver to a loudspeaker. Efforts to create a direct coupled single-ended triode power amplifier have been severely limited by the high voltages and low plate currents that are the province of tubes.

Power Mosfets have an interesting character in that they have relatively high distortion until you run quite a large amount of current through them. This makes them very suitable for pure Class A operation, particularly single-ended. It also makes them far less suitable for Class B and AB operation where they become quite non-linear near their cutoff point, and require a large amount of negative feedback correction to deliver clean output.

Not all power Mosfets are the same, either. The early Mosfets had much

As in art, classic audio components are the results of individual efforts and reflect a coherent underlying philosophy. They make a subjective and an objective statement of quality which is meant to be appreciated. It is essential that the circuitry of an audio component reflects a philosophy which address the subjective nature of its performance first and foremost.

Lacking an ability to completely characterize performance in an objective manner, we should take a step back from the resulting waveform and take into account the process by which it has been achieved. The history of what has been done to the music is important and must be considered a part of the result. Everything that has been done to the signal is embedded in it, however subtly.

Experience correlating what sounds good to knowledge of component design yields some general guidelines as to what will sound good and what will not.

Simplicity and a minimum number of components is a key element, and is well reflected in the quality of tube designs. The fewer pieces in series with the signal path, the better. This generally true even if adding just one more gain stage will improve the measured specs.

The characteristic of gain devices and their specific use is important. Individual variations in performance between like devices is important, as are differences in topological usage. All signal bearing devices contribute to the degradation, but there are some different characteristics worth attention. Low order nonlinearities are largely additive in quality, bringing false warmth and coloration, while abrupt high order nonlinearities are additive and subtractive, adding harshness while losing information to intermodulation.

Maximum intrinsic linearity is desired. This is the performance of the gain stages before feedback is applied. Experience suggests that feedback is a subtractive process; it removes distortion from the signal, but apparently some information as well. In many older designs, poor intrinsic linearity has been corrected out by large application of feedback, resulting in loss of warmth, space, and detail.

High idle current, or bias, is very desirable as a means of maximizing linearity, and gives an effect which is not only easily measured, but easily demonstrated: Take a Class A or other high bias amplifier and compare the sound with full bias and with bias reduced. (Bias adjustment is easily accomplished, as virtually every amplifier has a bias adjustment pot, but it should be done very carefully). As an experiment it has the virtue of only changing the bias and the expectations of the experimenter.

As the bias is reduced the perception of stage depth and ambiance will generally decrease. This perception of depth is influenced by the raw quantity of bias current.

air, the positive pressure perturbations will be slightly greater than the negative. From this we see that air is phase sensitive.

As a result of its single-ended nature, the harmonic content of air is primarily 2nd order, and most of the distortion of a single tone is second harmonic. Air’s distortion characteristic is monotonic, which is to say its distortion products decrease smoothly as the acoustic level decreases. This is an important element which has often been overlooked in audio design and is reflected in the poor quality of early solid state amplifiers and D/A and A/D converters. They are not monotonic: the distortion increases as the level decreases.

The usual electrical picture of an audio signal is as an AC waveform, without a DC component. Audio is represented as alternating voltage and current, where positive voltage and current alternates with negative in a reciprocal and symmetric fashion. This fiction is convenient because it lends itself to the use of an energy efficient design for amplifier power stages known as push-pull, where a "plus" side of an amplifier alternates operation with a "minus" side. Each side of a push-pull amplifier handles the audio signal alternately; the "plus" side supplying positive voltage and current to the loudspeaker, and the "minus" side supplying negative voltage and current.

Problems with push-pull amplifier designs associated with crossover distortion have been discussed elsewhere at length, and one of the primary results is non-monotonicity. Class B and many AB designs have distortion products which dramatically increase with decreasing signal. This is reduced greatly by Class A mode, but crossover distortion remains as a lower order discontinuity in the transfer curve.

For reproducing music as naturally as possible, push-pull symmetric operation is not the best approach. Air is not symmetric and does not have a push-pull characteristic. Sound in air is a perturbation around a positive pressure point. There is only positive pressure, more positive pressure, and less positive pressure.

Descriptions of push-pull often illustrate this type of operation with a picture of two men sawing a tree by hand, one on each side of the saw. Certainly this is an efficient way to cut down trees, but can you imagine two men playing a violin?

An analogy using a violin or similar stringed instrument illustrates singleended operation nicely and points out the control and finesse which can be achieved when only one gain device controls the performance of a gain stage.

By contrast, push pull Class A circuits have two opposing gain devices producing the output signal, and though it is industrially effective and efficient, it is not the most delicate way to amplify a signal. Push-pull circuits give rise to odd ordered harmonics, where the phase alignment reflects compression at both positive and negative peaks and crossover nonlinearity near the zero point.

Only one linear circuit topology delivers the appropriate characteristic, and that is the single- ended amplifier. Single ended amplification only comes in pure Class A, and is the least efficient form of power stage you can reasonably create, typically idling between three and five times the

lower transconductance and higher intrinsic resistance and distortion than the newer generations. They also were rather anemic in terms of their current, voltage, and wattage ratings.

On top of that, looking at the schematics of early and even contemporary Mosfet amplifier designs, we see that they usually have been simply dropped in as replacements for bipolar devices in Class B and AB designs, without regard for their particular linearity requirements, and without taking advantage of their unique characteristics.

Given the Mosfet characteristic, it is easy to understand why early and even contemporary amplifiers using them have not achieved the measure of sonic performance that the devices seemed to offer.

The promise of the transconductance characteristic in power amplifiers in providing the most realistic amplified representation of music is best fulfilled by Mosfets in single-ended Class A circuitry where it they be used very simply and biased to very high currents.

Last year I published a single-ended Class A power amplifier design in The Audio Amateur Magazine. It employs only one gain stage for the entire amplifier. Called the Zen amplifier (after all, what is the sound of one transistor clapping?) it illustrates the extremes of simplicity that can be achieved with Mosfets operated in single-ended Class A and high objective and subjective performance. More information on the Zen amplifier and its successor, the Son of Zen, is available from The Audio Amateur.

As yet, very few other single-ended solid state amplifiers are available on the market. This will change as the demand continues to increase and as other designers learn how to build them.

In the meantime, transformer coupled single-ended triode amplifiers are the alternative, using very large gapped-core transformers to avoid core saturation from the high DC current. These designs reflect more traditional thinking in single-ended amplification. They suffer the characteristic of a loosely coupled transformer, more limited wattage, and higher measured distortion than their solid state counterparts, however they still set the standard for midrange lucidity, and are not to be dismissed.

Besides being easier to use, the primary advantage of Mosfets over tubes is that they operate at voltages and currents appropriate to loudspeakers without conversion, and do not require an output transformer.

Regardless of the type of gain device, in systems where the utmost in natural reproduction is the goal, simple single-ended Class A circuits are the topologies of choice.

Here is one of them Aleph-0 , I think there are more powerful ones 1 2 3 4 or 5?
https://www.passlabs.com/wp-content/uploads/2020/05/a0man.pdf

Scroll to the bottom for all the Aleph's https://www.passlabs.com/legacy-products/

Cheers George

Honestly, did not carefully read all of the feedback.  Sugden mono blocks!  Badass power!  Musical!  Wretchedly fast!

I've owned lots of Sugden amplification and a 300B Manley preamp.  Yes, I know that is not a 300B based amp.  But, the immediacy of Class A, the slam of Class A and the timbre of Class A is simply addicting.

Anything anybody does with tubes is simply slow and very colored.  I've run VTL, Manley, a highly modified Mercury 3 and it's all wonderful.  Wonderfully, warm and rich and colored and slow.

If that's your style so be it.  I've left tubes permanently.  I run a Sugden Masterclass preamp and all active class A/B active speakers.  Done.  Best of luck and enjoy whatever you get.

steveashe
I just sold my Pass XA25. The AGD Audions are that good and more. The XA25 is no question a very good amp once you get pass about 200hrs. The AGD amps just deliver more goodness i compared the amps side by side for over a month, there was no contest the AGD amp was superior in my opinion and i must say it was not even close. AGD gives a trial period, you won't be sorry once you hear them.

False.

Anything anybody does with tubes is simply slow and very colored.

Symphonic line kraft

"Anything anybody does with tubes is simply slow and very colored"

If that's his conclusion,  so be it  for him. Not even remotely close to my listening experiences. Horses for courses once again. 

+1 @david_ten. I guess we hear similarly 😊.
Charles   

Anything anybody does with tubes is simply slow and very colored.

Nonsense! The output section of our amps is 600V/uV. Most solid state amps aren't that fast.


We've been working on our own class D project for the last 4 years which is now in Beta production. Its nice to be able to say that they don't sound significantly different from our tubes amps although they have considerably less distortion (most of it in the case of either amp is lower ordered harmonics). Put another way tube amps can be quite neutral.

ignorant ridiculous blanket statements don't even deserve a response 👎

and i think nelson pass should summarize 'war and peace'  😆

Yes, I am now an owner and major fan of AGD. I am so impressed with my $8350 Audions that I am considering upgrading to the top line Gran Vivaces. However, I can’t imagine any amp sounding better than my entry level AGD Audions. But that is always the case with upgrading. One thing I now know for sure, I have never heard any amp that competes with the SQ of AGD. Class D truly can sound very good. But AGD amps are based on a patented GAN module developed specifically for Audio. Other GAN amps available use GAN transistors used in radar, lidar, etc. The result is that I now hear a level of transparency that reveals the heart and soul of musicians.
The experience is new, transformative and unlike anything I have ever heard in 50 years.  A “fan boy”? Boy hoody!

@atmasphere 

Ralph, glad to hear about the beta production and perception of their sound. Any guidance you can provide on expected timeline to market, mono/stereo, power, estimated price range for your class D?

I have to agree that AGD amps really are that good. At the time that I demoed them I had an XA-25 and the SIT-3 (as well as Line Magnetic LM-508ia), I was already immersed in GREAT sound and yet these AGDs were something altogether different. I had never heard a sound so distortion-free. The clarity itself was a revelation to my ears.
Re-visiting my album collection was a thrilling adventure! Every genre from classical to heavy metal sounded incredible and fresh to these ears. It was like a film (distortion) had been removed and the subtleties of instrument articulation were now so much more apparent. Especially acoustic instruments.

Loudspeakers I’m using at present are Tekton Encores. 

Ralph, glad to hear about the beta production and perception of their sound. Any guidance you can provide on expected timeline to market, mono/stereo, power, estimated price range for your class D?

The Beta production amps are monoblock, 100 w into 8 ohms and 200 into 4. They have balanced and single-ended inputs. Depending on solutions to supply chain interruptions we might be August or September although we've already shipped the first one. Price is 5100/pair.

Speakers are Wilson Watt Puppy 5.1, Watt Puppy 6, Wilson XLF and Devore super Nines. Speaker wire AN pure silver 20k for 10ft. Shunyata Omega USB cable to custom built LampaZator DAC to Supratek DHT pre using 45 tubes, Audio Note pure silver IC's to AGD amps.

The inclusion of the AGD amps have taken my system to another level.

My final speakers are the Canadian Tetra 606.
To my ear, most real sounding speakers I have heard.
TetraSpeakers.com unique website and company with rave endorsements from among the world’s top musicians.
They know what music sounds like. Herbie Hancock has 5 pair (including 606s). Keith Richards went on tour with his pair.

The real question is how tubey are you. That's the question you need to answer for yourself. Best wishes!

I think any good surfer wants to get tubed.

The Tetra 606s are 91db and 6 ohms minimal.
Think that the Audions well power them. But IME, all speakers like more power. And, I think, the Gran Vivace also has noticeably fuller sound that takes things to a different level. Although I also think that there will be significantly diminishing returns. The Audions are overachievers.

Pass LABS First Watt amps!

There are some excellent solid state amps for you but they will not be from the brands that you will think they will be from, do some listening and discover how great solid state can be again.

@mglik , have you ever found your answer?

First Watt SIT-3 if you can find one or the new FW SIT-4 should make you happy. I alternate between my SIT-3 amp and 300b Franks on my Horning Eufrodite Elipse.

They both sound wonderful with the rest of my equipment!

@snopro 

It's always good to see a post from you. I'm glad you still have and are enjoying your Horning speakers. Do the S.I.T.-3  and Frankensteins clearly have a sonic advantage in any specific/particular way in direct comparison with each other?

Charles

@charles1dad 

Hi Charles thx for your kind words. The feeling is mutual my friend!

Don't really post much but, do check the site regularly. I don't know what is happening made a long post twice and it disappeared! I'll just get straight to the point. The Franks have a deeper soundstage and have a little more purity in the mids and highs. The SIT-3 has a wider soundstage and the bass goes deeper and is more articulate.

They are both grainless and have a beautiful musical and natural sound. The speakers totally disappear! I can listen for hours with zero fatigue. People who are in this hobby for a long time know what I'm talking about. No hi-fi sound here just pure music! 

I love them both for the reasons stated. The Hijiri Takumi PC's (really expensive) brought it to a higher level. I worked on the streaming side of things and it improved the digital side a lot. It is very close to analog now depending on the recording.

I'm very happy and quite satisfied and can honestly say I can live with this setup for a long time!

Sorry for side tracking this post 

@snopro

I appreciate you taking the time to respond. Thank you. You’re in a very good place with your system.

Charles