[Freo-1]

Nice setup, Phil. 


Do you know what mods were done to your amp?

[dwmaggie]

I run the Peachtree AMP 500 and have heard no turn on transients or thumps, zero noise.  I also use 3 different DAC Cherry variations with zero noise issues.  I also bought the Mini Gan 5 at the introductory price of 650, It also is silent.  I am slowly trading or giving away the old heavy, high current AB power amps.  Been running a class D for nearly 3 years with zero issues or problems.  Speakers are Magnepan 1.7i.

[Tyson]

The GaN amps I've heard are certainly a step up over the old Class D amps. 

[Phil A]

Nice setup, Phil. 


Do you know what mods were done to your amp?

Link was posted earlier - http://tweakaudio.com/EVS-2/Voyager_amp_mods.html   Ric was originally going to charge $450 vs. $500 (for the mod) and the person who bought the amp paid $225 (being the first) plus shipping back and forth (he isn't that far from Ric - just a few hours). 

I know what is meant by big heavy amps.  I've owned a bunch.  I originally bought a Mivera SE (IcePower Class D) amp and intended to use it in a secondary system (a friend had bugged me about Class D).  I was surpised how it bested the amp I had in that secondary system and even more surprised when I put it in the main system and it bested one of those heavy amps that listed for $9k at the time (now it is $11k list and I traded mine even up for a Hegel H190 integrated for a secondary system and recently sold that) and there is one for sale right now with an asking price of $3.1k (for a month) and still there.  For a current model amp to be listed at just over one quarter of its list should be a clue that Class D has come a long way.  The reason I traded mine is that there was a bunch of them listed and not selling and after a few months of trying to get around $4k I just figured it would be good to let it go (I got it as a show demo at a good deal years before and figured for the amount of time I had it it was a reasonable rental). 

It's like anything else technology wise.  People tend to hang on to their old opinions.  It happened in the watch industry where they thought the quartz watch was a worthless new fad.  Audiophiles in particular (probably excepting those into the ultra high end cost no object components which tend to surpass the more reasnable things if one of course can afford them), hang on to their impressions when they hear things about electronics of a certain brand or type.  If someone has heard something, even years back, for whatever reason they didn't like it makes an impression and they tend to dismiss future designs of the same brand or technology.  I see comments all the time made about things from those who have not heard the components.  There's nothing wrong with hearing anything and not liking it.  I'm happy their are many choices which a person can buy to suit their tastes.

[Jon L]

Link was posted earlier - http://tweakaudio.com/EVS-2/Voyager_amp_mods.html   Ric was originally going to charge $450 vs. $500 (for the mod)

I've had Ric mod a few things in the past.
"The stock feet are not great (soft rubbery sounding).  Please upgrade the feet to spring things or other better feet.  I love the best Mad Scientist feet ($300 a set plus shipping).  However, people are getting good results from these cheap spring thangs"

I just noticed this.  Great minds must think alike b/c I did settle on one of those "cheap spring thangs" for the GaN amp, albeit I currently use only one spring per foot. (old photo below shows 3 springs per foot). 

1221211728_HDR by drjlo2, on Flickr

[Phil A]

I've had Ric mod a few things in the past.
"The stock feet are not great (soft rubbery sounding).  Please upgrade the feet to spring things or other better feet.  I love the best Mad Scientist feet ($300 a set plus shipping).  However, people are getting good results from these cheap spring thangs"

I just noticed this.  Great minds must think alike b/c I did settle on one of those "cheap spring thangs" for the GaN amp, albeit I currently use only one spring per foot. (old photo below shows 3 springs per foot). 

1221211728_HDR by drjlo2, on Flickr

I already had the Mad Scientist feet from my EVS1200 (which I moved into a secondary system and it has no feet and I'm using something else on them) and just stuck them under the Voyager.

[Freo-1]

I was a early user of Class D.  Back in the early 2000's, I had a Sony STR DA-9000 and 7100, when multi channel was all the range.  The Sony approach used Pulse Length Modulation vs. Pulse Width Modulation.  They actually sounded pretty decent for the time, and easily sounded better than the high end Yamaha amps of the time.  However, when I went back to two channel audio, shifted to Threshold/Pass Labs amps.  Also tried McIntosh amps, and while they look cool, they just did not measured up sonically to the Pass gear.


My opinion of Class D changed dramatically once I heard Devialet.  Although the Devialet approach is not pure Class D (voltage is Class A, current is Class D), the ease of usage, size, and superior sound sure changed my mind regarding the use of Class D.  When one considers that a used Devialet D-Premier can be had for around 3K, by today's high end standards, a fully integrated amp with built in DAC and phono stage can be considered a bargain (but I digress).


Once I obtained the Chord M-Scaler and TT2 DAC, I came to realize just how important digital processing is to the playback chain.  When the Chord setup is connected to a pair of 90 watt tube amps, the sound was transformed.  Couldn't believe it was the same amp driving the speakers.  So, based on this experience, decided to try the Gan400 with the Chord setup to see if similar (or better) results could be obtained.  The reviews to date indicate that the GanFET's can make Class D provide the best of both tube and SS.


After looking into the EVS mods, not convinced that the changes will actually make any measurable differences.  Things like non-inductive resistors, coupling caps to me can make a difference, but the changes mentioned for the Class D amps to me are suspect for any actual sonic improvement. 

[Freo-1]

One thing I did work out is that the Peachtree Gan400 does have a different power supply board from the LSA Voyager 350.  That would account for the differences in specs between the two units.

[Stercom]

One thing I did work out is that the Peachtree Gan400 does have a different power supply board from the LSA Voyager 350.  That would account for the differences in specs between the two units.

What are the differences in the power supplies between the Peachtree and LSA?

[Freo-1]

The boards look different physically.  There is a thread on ASR that discusses this.


Found interesting articles regarding GanFETs:


https://www.eeworldonline.com/the-final-frontier-class-d-and-gan-take-on-hifi-audio/


https://audiophilereview.com/cd-dac-digital/why-well-soon-be-living-in-a-class-d-world/

[Stercom]

You have a link concerning the discussion on the different power supplies?  All I see on ASR is guys saying the LSA and the mini GAN not meeting published specs. 

[Freo-1]

You have a link concerning the discussion on the different power supplies?  All I see on ASR is guys saying the LSA and the mini GAN not meeting published specs.

https://www.audiosciencereview.com/forum/index.php?threads/lsa-voyager-gan-350-review-stereo-amplifier.28115/page-4

[Stercom]

They really seem to hate these amps over on ASR, especially the LSA! Wow!

[Freo-1]

They really seem to hate these amps over on ASR, especially the LSA! Wow!

Yes. Amir listening skills are questioned  by many  at best.  They focus on measurements much more than anything else.  Some of the gear that site gushes over sounds rather brittle to many others.


As they say, Horses for courses. 

[Stercom]

Agreed

[Freo-1]

If one conducts an internet search on elegant audio solutions gan boards site, a list of links with .pdf papers explaining the boards will appear.




https://www.eeworldonline.com/class-d-audio-gallium-nitride-versus-silicon-virtual-roundtable-part-2-of-2/

[Freo-1]

They really seem to hate these amps over on ASR, especially the LSA! Wow!

Most of the complaints about the LSA are in reference to the shoddy build quality with the test sample. 

[Tyson]

The ASR people seem to really love the Hypex based amps.  Probably because they measure incredibly well.  But here's the thing that I feel like they don't give enough consideration to - the amount of feedback needed to get those great measurements.  Most solid state output devices are not linear.  So they need help (feedback) to make them acceptably linear.  SS amps require a fair bit, while a lot of the class D amps require a ton of feedback.  IME, the more feedback you use, the less open and more closed off the amp ends up sounding.  So you end up with an amp that has amazing grip on the speaker (and incredible measurements), but an overall sound that is percussive but airless.  Almost constipated sounding. 

Which is why so many people prefer tubes - they are much more linear devices, and require much less (or zero) feedback to measure acceptably.  You end up with worse measurements and less grip on the speaker, but an overall more natural and less constipated sound. 

[Freo-1]

The ASR people seem to really love the Hypex based amps.  Probably because they measure incredibly well.  But here's the thing that I feel like they don't give enough consideration to - the amount of feedback needed to get those great measurements.  Most solid state output devices are not linear.  So they need help (feedback) to make them acceptably linear.  SS amps require a fair bit, while a lot of the class D amps require a ton of feedback.  IME, the more feedback you use, the less open and more closed off the amp ends up sounding.  So you end up with an amp that has amazing grip on the speaker (and incredible measurements), but an overall sound that is percussive but airless.  Almost constipated sounding. 

Which is why so many people prefer tubes - they are much more linear devices, and require much less (or zero) feedback to measure acceptably.  You end up with worse measurements and less grip on the speaker, but an overall more natural and less constipated sound.

If one reads the links posted regarding GanFETs,  they make the same argument outlined here.  They have much different behavior than MOSFETS.  GanFETs have the linear behavior of tubes, while maintaining control of speakers like SS. 

[RonN5]

Interesting posts on ASR by Atmasphere re: Class d & GanFet

We have been working on a class D project for about the last 5 years. It was about 6 years ago that I heard class D amps that convinced me the writing was on the wall and if an audio manufacturer didn't have a class D amp of their own in due time they would be left behind. My goal has always been to make amps that are neutral rather than amps that imbue a nice coloration. You are quite correct that OTLs have limited application since output impedance is always an issue except with the most powerful examples (which apparently we make). Some people do use them to get colorations as they do SETs but I don't count myself amongst them.

The amp we designed employs about 37dB of feedback at all frequencies in the audio band. Its distortion is considerably lower than our OTLs, but interestingly if both amps are on a speaker benign to the OTL, they are difficult to tell apart. This makes sense because most of the distortion of our OTLs is lower ordered; the amps are fully differential from input to output so the 3rd harmonic tends to be the primary distortion component, and the ear assigns the same tonality to the 3rd as it does the 2nd (which is to say it imparts a bit of warmth). There is enough of it that it is masking the higher orders. So the big difference you hear between the two tends to be in the bass because the class D is acting as a voltage source (its output impedance is a few milliOhms) while the OTL isn't.

I feel that you need to get well below 0.01% THD unless the distortion signature allows for the higher orders to be masked. If not an amp with that much THD can still sound bright; that is how sensitive the ear is to the higher orders (as I explained earlier). Somewhere around 0.001% I feel is really getting somewhere. You need to be -100db or more IMO.

IME the sensitivity the ear has to the higher orders is grossly downplayed by the industry and its incantations of 'negligible distortion' are often false. Like many things in life, its more complex than that. To me the missing link is understanding how the ear/brain system perceives sound; what's important and what is not (and so applying engineering to take advantage of that). A lot of that has only been found out in the last 30 years or so; IMO not enough of that understanding is applied when we do the measurements; distortion vs frequency is a good step in the right direction due to that pesky Gain Bandwidth Product thing.

And a second post:

A tube amp for me is more fun; class D amps are far more challenging IMO although the modulator is the easy part. We're working with GaNFETs and they are the difficult bit as they are so fast- you can have noise at crazy frequencies at which they are perfectly capable of switching. So you can run into heat problems due to this kind of noise, which might be 50MHz. Obviously this affects cerification issues; every time we make even a minor change we have to do an enourmous amount of testing to see to it that there isn't some sort of noise problem introduced with the change.


I interpret this and everything else in this thread as buy from someone you trust and make sure you can try it out in your home system before buying.