GaN amps: Peachtree or LSA Voyager?

Cary's 805 had a variable feedback control.  I don't know how many other amps were made with this feature.

Lots. Starting in the 1950s.

@snapsc 

I can't see why it would not be possible. Distortion is just harmonics of the original signal. I expect there would be some complexity. The distortion would be influenced by signal level and I expect frequency. I am sure there are lots of people who could do that if they put their mind to it.

@markmuse 

It would be great if you continue to report back on your experience with the M225s.  Frank Van Alstine is quoted in the Absolute Sound review as saying that one of the goals with this amplifier was to, as much as possible, completely eliminate harmonic distortion.  And I'm guessing that this design goal in conjunction with the amp operating in Class A...possibly up to 20 watts are the reasons it has been getting great reviews.

It doesn't seem like anything revolutionary, but then again as with most things audio, the implementation is the key.  To his credit, Frank says that this is not the be all end all design and it has been his experience that they are many designs that have ended up with excellent amps.

Out of the box - i would say 90% of what i have owned  over the last 30 years - sounded really good

 

 if you can say that you still like them in 30 days - then those amps are special

I don't entirely disagree with you. It does take some time to get to know the sonic personality of the equipment involved, but my experience with new out of box is that the items usually sound congested and harsh relative to where they will end up. 

a good point @smargo 

markmuse - Out of the box - i would say 90% of what i have owned  over the last 30 years - sounded really good

 if you can say that you still like them in 30 days - then those amps are special

Received my Van Alstine 225M amps yesterday. First impression: If listening straight out of the box is any indication, these are going to be very musical amps. There is a little bit of an edge to dynamic peaks - if I am lucky this will fade as they burn in. Otherwise I am already happy. Extraordinary performance for the money.

Cary's 805 had a variable feedback control.  I don't know how many other amps were made with this feature.

@deludedaudiophile 

I guess I've thought of amps as being in several varieties of late...

those that are either class a or class a/b operating in class a for a while that are using their class a operation to emphasize the lower orders of harmonic distortion in order to be more musical

those that try to drive distortion as low as possible, Benchmark and some of the class d and ganfet amps come to mind, that feel that any distortion that influences sound is wrong

and obviously tube amps

I've thought of DSP as trying to offset room issues by modifying frequency response and possibly reflections and timing..but not the distortion profile...is this even possible?

@snapsc, would that not be easier to accomplish with DSP?

Is it not possible with both Class d and Class A/B amps to engineer the amp to the lowest possible distortion and then add back enough 2nd and 3rd harmonics to give the amp the degree of musicality desired? And if so, could a "distortion" dial be added to allow the user to fine tune the sound to their liking?

Theoretically, to the former, possibly ’yes’. To the latter, likely ’no’ since such a control would have to modify some parameter of the amplifier that might be critical and not take kindly to such an adjustment.

I wouldn’t hold your breathe for such a thing. Usually designers of solid state are very conscious of the ’numbers guys’ that only look at specs and poo-poo the listening experience, even if the latter is what its all about. So they often try to get the distortion as low as they can and anything that raises it is anathema. There are a few that are careful about how their designs make distortion; Nelson Pass is an example.

@atmasphere 
 

One thing I don't understand from much of the above discussion....  Is it not possible with both Class d and Class A/B amps to engineer the amp to the lowest possible distortion and then add back enough 2nd and 3rd harmonics to give the amp the degree of musicality desired?  And if so, could a "distortion" dial be added to allow the user to fine tune the sound to their liking?

I see an often quoted limit of 0.1% as being the absolute lowest than can be detected, and I think normally much higher.

@deludedaudiophile If that were primarily lower ordered harmonics that could well be true.

But otherwise that statement is false. The problem, frequently ignored, is that the ear uses the higher ordered harmonics (5th and above) to sense sound pressure. Keeping in mind of course that the ear has about a 130dB range!! -so its keenly sensitive to these harmonics! It also assigns tonality to all forms of distortion.

The higher orders can be only 0.01% or even 0.005%; if not masked by the lower orders, they will cause harshness and brightness. We've been hearing this in solid state amps for the last 60 years, so there are literally millions of references on the web!

We've known since the 1930s how sensitive the ear is to the higher orders (see Radiotron Designer's Handbook, 3rd edition). Its also very easy to demonstrate with very simple test equipment that the ear indeed uses the higher orders to sense sound pressure.

For the most part class AB solid state designs have ignored these facts in pursuit of the almighty dollar over the last 60 years. Of course, back in the 1960-1980s the semiconductors needed to overcome the problem simply didn't exist (and it seems the will to design something properly didn't exist either...). Instead, propaganda was generated to make you think you were hearing something 'neutral'. But its the Emperor's New Clothes; the simple fact is that brightness and harshness is a coloration- its not neutral.

@atmasphere Thanks for the explanation. They are due here tomorrow, so we shall see.

@atmasphere

Is there a reference for the -105db? That sounds excessive. Do you mean at a single frequency or all frequencies (I assume 10KHz and under?). I see an often quoted limit of 0.1% as being the absolute lowest than can be detected, and I think normally much higher.

The A/Bs I'm talking about are the Van Alstine DVA M225 monos. Surely you know Frank and his products. Care to comment on his matching GBP to feedback?

There's no way to tell from the information on the web. But I can tell you this: in conventional class AB amps the distortion numbers you need to see have to be quite low (0.000x), because higher ordered harmonics are a common thing in AB circuits. About the only way you can mask their presence since the lower orders are not available for this is for the distortion to be below -105dB! That means a lot of feedback, something quite challenging to achieve in an AB design. If the amp does not meet this criteria, its likely to have brightness.

@atmasphere OK, Ralph, gonna put you on the spot. I wouldn't do this except that you sort of volunteered. The A/Bs I'm talking about are the Van Alstine DVA M225 monos. Surely you know Frank and his products. Care to comment on his matching GBP to feedback? (By the way, this kind of tech stuff is way over my head so I'm not taking a position other than I'm sure you know what you are talking about). 

reading up on Gain Bandwidth Product, it seems to be present with designs using the bipolar junction transistor. 

@mrdecibel to be clear, all circuits with gain have Gain Bandwidth Product. The question is does it have enough to support the feedback its designed with? If not, there will be a corner frequency where feedback will begin to decrease. This problem has been present in all amplifier designs until only very recently!

If you want the amp to sound smooth and relaxed at all frequencies, its crucial that the feedback be consistent at all frequencies, otherwise its not going to happen.

@atmasphere reading up on Gain Bandwidth Product, it seems to be present with designs using the bipolar junction transistor. 

I’m very curious what good A/B brings to the party.

'Harsh and bright', IME, unless the designer has really done their homework and has enough Gain Bandwidth Product in the design to support the feedback it employs. If not, the feedback will decrease as frequency is increased and will be one of the reasons for increased distortion at higher frequencies. This in turn results in harshness and brightness (especially at higher volume levels) since the ear assigns that tonality to distortions in the upper end of the spectrum.

That is one advantage that some class D amps have over conventional AB amps.

@mrdecibel Thanks! Yes, looking for that lost chord. The Bel Cantos are close though. So many choices. I’m very curious what good A/B brings to the party. If this doesn’t work out it will be GaN of some flavor.

JR 535 ? Bel Canto 600 Ms ? Great amps, with their own flavors and personalities. Just need to find " the ONE ", which is not easy. Good luck.........My best, MrD.

@tweak1 thanks for the update.

Price-range is important but SQ is much more important. Even so, Orchard mono blocks are i think arround $1500, i don't really need much power and apparently they sound clean. I may still be tented to take Voyager for about 2k.

@niodari

Having been both a dealer and an audiophile for many decades, and having owned plenty of amps, including SS, tube, and hybrids, after 1.5 years owning a Voyager, there really isn’t much in the $3K range that comes close, new or used. Any perceived shortcomings are likely coming from what is upstream from it, be they components, cables, iso/vib control, PLC, quality of the electricity, lack of quality contact enhancements, or downstream; speakers, room treatments... so if you can get any money off the $3K, it’s a bonus

@niodari Just got a notice that they have shipped. Fingers crossed!

@tweak1 I ordered a couple of add-ons from Ric. Other than that I will have to see how the amps perform. 

@markmuse 

I think Ric Schultz mods the M225s

I read good things about SET 120 amplifier. The monoblocks seem to share the same design strategy with more power and perhaps some refinement. Shouldn't be a bad choice. Keep us posted.

@niodari I like what I’ve been reading about the M225 monos, so I’m going to see this one through. I will report back. Might be a couple of weeks before they ship.

Wolter has sale on the Voyager and ships next day after payment. Perhaps it may be worth of risk if he lets you it for 2k. It's upon you.

Well, I followed up a lead from another post and, well... I canceled the Benchmark order and ordered a pair of Van Alstine DVA M225 monos. I sure hope this is my last pair of amps (and not because of a shortened lifespan)! 

By the way I still have a Jeff Rowland 535 and a pair of Bel Canto 600M monos to sell. Ahem, yes, and a pair of KEF Reference 1's, almost brand new. 

@markmuse The LA4 + AHB2 is an awesome combo but I think an acquired taste. A warmer preamp (like my CODA 07x) and the AHB2 is likely a great choice for most.

If you decide to sell a BLACK AHB2 in the future let me know, I need to eventually go back to mono blocks.

Benchmark is not expecting to ship my amp until May 30. They say they are backup with orders. 

@ddonicht please keep us posted on your further impressions on the Voyager and tell us more about your system.

Enjoy the new amp

I just received my Voyager yesterday.  So far it sounds better than my Emotiva BasX but you would expect so since they are very different price points.  I have not used the Peachtree so unfortunately I cannot give you a comparison.  

@smargo Try to concentrate on the features that you like in the sound of your system that will help you to enjoy how the music sounds in your system. I try to enjoy both, music itself and sound quality simultaneously. But it is more or less common to get accustomed to a good SQ that you may have in your system. I found it particularly useful  to compare between each other how different amps, cd players, DACs  sound. Then you may note what is that you really like in a particular audio equipment. If your components are good, you will always find a pleasant feature  of every unit. Otherwise, you may get read of that unit. This kid of comparison may help you to appreciate more and value the SQ that a particular component and the whole system gives you. I have three audio systems and like the sound of each of them in different ways. When i feel that a particular gear no more meets my demands, i try to replace it, but not necessarily with a more expensive gear. I changed a number of amplifiers during last years, class A, Class AB, class D. This helped me to understand more the nature of the sound and the features of each unit of gear. I sold a few of my amplifiers. Each of them i liked in some particular ways. As i like music, I like women, in general. In each individual woman i may like some particular things, different for different individuals. looking at a number of charming women, it might be difficult to choose one, you may like each of them in different ways. Something similar happens with audio gear when you really learn to value each individual unit. Once i tried different amps, i am starting to understand why my 20 year old push-pull tube integrated amp is so good. I needed to go through all these amps to understand that. You may also simplify your system. I personally found that not necessarily separate components give better overall result and started to appreciate integrated amplifiers, just an example. Having three different audio systems i can compare the differences. Not necessarily all  recordings sound better in my main system, which costs a number of times more than the other two. Sometimes i replace expensive amps with a cheaper ones with a success. If you want to know, just tomorrow i expect to receive  a relatively modest Nuprime ST10 amp. Finally, i took this simple choice because a local Nuprime dealer has proposed the amp, a slightly used one with a very reasonable cost. I think it should not be a terribly sounding class D amp. 

So try first to enjoy really  what you have. Then you will really know if you need to change something. The joy is your treasure. Do not force yourself. 

"Over on the other selling site, there's someone unloading their LSA right now for $1700.  They can't have had it for very long, wonder why they're selling."

whats the difference why - ive had about 50 different pieces of gear over the last 30 years - most times i just get tired of the sound eventually - always thinking i either want to buy something that would provide an upgrade - (always more expensive) or i want to simplify my system

@lewinskih01 Thanks, will do.

@niodari Thanks, will do.

Mark, good luck with the Benchmark. I've been also eyeing the LSA and Peachtree GaN, and while the Benchmark isn't on my list (per what I've seen in posts) I would be interested in your first-hand experience. Keep us posted please.

@kuribo We get it. There is no need to keep repeating yourself. 

I don't believe that audio is religion

Not for those who base their decisions on rational thought, logic, and science. For those who blindly believe the baseless claims made by charlatans who take their money on simple blind faith, it is indeed a religion. That is the essence of religion: it's a faith based believe system. When we base our decisions on the opinions and unsubstantiated claims of others and disregard reason, logic, and science, we have become "true believers". Welcome to the cult!

On another note, who is experiencing turn on thump/noise with the Peachtree?

Pretty sure Wally will knock off a grand if you buy the LSA.

Andrew had a return policy that made the GaN400 around $1500. 

@kuribo , i didn't know that both of you are dealers/producers.




 

No, we are not both dealers/producers. I do not sell anything nor market any commercial products.

@markmuse , thanks for letting us know your choice. Please keep us posted on your first impressions on the Benchmark amp!

@kuribo , i didn't know that both of you are dealers/producers. I still did not take a final decision. I don't believe that audio is religion, and i don't care too much about religion since it is basically converted to a bureaucratic institution. Still,i think that  religion helps to people. I rather try to believe that  God is everywhere and that he has to do with everything. 

Over on the other selling site, there's someone unloading their LSA right now for $1700.  They can't have had it for very long, wonder why they're selling.

nope.   You can find both for less than $2K

@mbolek , this sounds good. did you mean used, otherwise,  do you have an idea where? 

It has nothing to do with ego, the amp is what it is and the load dependent frequency response is a simple fact.

When people come here asking for information I take them at their word that they are looking for factual data. Clearly some don't want that. That's fine.

I have no self interest in this choice. I am not trying to sell anything.

If you believe audio is a religion, you have found your savior. Perhaps he can perform a miracle and turn your poorly designed amp into something magnificent. Just remember: Jesus never charged for his miracles.

Best of luck.

I bought the Benchmark AHB2 amplifier. Don't know yet when I will receive it. My thinking is there is a return period; it is well regarded so if I decide to sell after the return period I should have no trouble; I had their LA-4 pre for a while and it was a very good piece; I am hoping my tube preamp will keep the sound from being dry. 

Thanks everyone for your opinion.

Can’t go wrong with the LSA or Peachtree at <$2k.

Sure. Did you mean <$3K?

nope.   You can find both for less than $2K

@ricevs i have already noted that i love your posts. And I am liking them now even more. You gave a most difficult task - to stop ego. If I am too weak to do so, at least i can admire your belief. 

...And look at the last post suggesting again Orchard Audio GaN amp, once I am to order the Voyager (am I taking a correct decision?) . I have no idea how either of the two amps sound, and I don't completely trust measurements (the nature is more complex than classical (non-quantum) physics can describe). Distortion is no good but perhaps is unavoidable for more complete and realistic sound reproduction? 

How these two amps sound is more important for me, and i don't have that information. And one is on sale, the others are not.