[cheesey]

I would stay away from the GaN amps as nearly all but Orchard have load dependent frequency response. The current state of the art is Purifi with Hypex a close second. Both have inaudible distortion, load invariant frequency response, run cool and will drive just about any load. Prices are very reasonable- I paid around $2400 for a set of 9040 Purifi monoblocks with 900W into 2 ohms, auto on/off feature, selectable gain, etc. No brainer.

[NIGHTFALL1970]

Phil, what were the other A/B amps that you used before? What did you like better about the class D?
I am curious about the new Bryston class D. Have you ever heard them?

[rotarius]

Not a good showing.
https://www.audiosciencereview.com/forum/index.php?threads/premium-audio-mini-gan-5-review-stereo-amplifier.27118/

[RDavidson]

To be clear, I’m not here to chase specifications or test results. If that was the case I’d just buy whatever ASR says is best and be done. These tests don’t tell me anything about people’s real world experiences however. That’s what I’m most interested in.

With that said, I think virtually all, well-engineered, class D permutations range from good to excellent. Load invariance is nice, but doesn’t really matter when most of these amps can output 200 wpc into 4 ohms continuous. This is more than enough load invariance when I’m only using maybe 1 watt at typical listening levels in my room with my speakers.

[DannyBadorine]

Thanks DannyB! That’s very encouraging news. From my understanding, Buckeye is indeed legit and I like that everything they make is user-serviceable (no solder skills needed!). That’s pretty great! There may be some advantages to more expensive options (nicer chassis, better power supply, etc etc) but I kinda like the no-frills modules in a box approach here. If I ever replace it, then it’ll just become a garage amp or subwoofer amp or something later, and I won’t feel bad about having another piece of gear that’s “too nice” for the job. How do you feel about NCore vs Purifi? I’ve read that Purifi is a bit more pleasant and less “dry.” Are there other worthwhile qualities? Better imaging maybe? It seems like I could be just as well with a lower cost Ncore unit, but the Purifi options are still reasonably priced and more state-of-the-art.

I don't hear a difference between Purifi and Hypex amps, but I haven't A/B'ed them directly.  I never liked the Ice modules due to some weirdness in the top end but when I got my first Hypex amp I was converted.  All Class D sounds "dry" to me because it's just far more accurate and uncolored.  But that's what I like.  I like my audio systems to accurately reproduce what is put into them, especially my amplifiers.  I don't want the amp changing things (except for making it louder).  A low distortion, non-frequency dependent amplifier is generally going to have better imaging (in my opinion) because it is more accurate.  But your room and speakers will have a much bigger impact on that.  That's why I love Buckeye Class D because they're so affordable I can put more money where it matters; my speakers and my room.  So, that's why I recommend the Hypex Ncore, because the difference between them and the Purifi is very small, if any and your money is better spent somewhere else like speakers or room treatment.
I also saw someone mention the Benchmark amplifier.  I don't have that but I have their preamp and it is so clean and transparent.  I think they make amazing stuff.

[DannyBadorine]

I would stay away from the GaN amps as nearly all but Orchard have load dependent frequency response. The current state of the art is Purifi with Hypex a close second. Both have inaudible distortion, load invariant frequency response, run cool and will drive just about any load. Prices are very reasonable- I paid around $2400 for a set of 9040 Purifi monoblocks with 900W into 2 ohms, auto on/off feature, selectable gain, etc. No brainer.

I agree with this 100%.  I just buy Buckeye because it's the same performance for cheaper.  I've run them down to 2 ohms as loud as they can go and there's never a problem.

[Phil A]

Not a good showing.
https://www.audiosciencereview.com/forum/index.php?threads/premium-audio-mini-gan-5-review-stereo-amplifier.27118/

That site has been discussed many times here (e.g. https://www.audiocircle.com/index.php?topic=184676.0) and many other places (e.g. https://forum.marchaudio.com/index.php?threads/incompetent-internet-reviewers-beware.19/).  Whatever anyone likes or wishes to believe is fine.  We all listen in different rooms (which of course impacts the sound) and have different tastes.

[Phil A]

Phil, what were the other A/B amps that you used before? What did you like better about the class D?
I am curious about the new Bryston class D. Have you ever heard them?

I've not heard the Bryston Class D amplifiers.  Unfortunately where I live for the past 11+ years, there are very few audio dealers aound.  I have one dealer about 15 minutes away (and I have more equipment and rooms than he does) and he concentrates more on the ultra expensive things with limited floor space.  The next closest dealer is probably a couple of hours away and they also don't carry as many things compared to the way the audio industry was many moons ago.

I have my Thiel 3.7s since they first came out (2009?).  I had Thiel 7.2s before that.  The 7.2s were bigger and a harder load to drive.  Since I've had the 3.7s (and there are pictures in my Gallery over many years of my main and secondary systems), I've owned a Bryston 14BSST (and they have the cubed series now which I have not heard except briefly at a show) and a Modwright KWA 150 SE (which I believe was discontinued a bit over a year ago).  I also had used with the 7.2s Proceed HPA amps many moons ago.

I still use my Modwright LS36.5 DM (dual mono) 2 box preamp (which has HT Bypass since I have an integrated HT and 2-channel system).  The current (Purifi Class D) amp in the main system is the third class D I've had in there.  For a short while, I had the (Premium Audio) mini GaN amp in the main system for HT duty.  I used another pair of speaker cables and would just swap them in back of the speaker.  I didn't do any critical listening for music but the mini GaN amp had no trouble on movies driving my 3.7s.

This is a current picture of the main system:

[Phil A]

This is the system where the mini GaN amp now resides:

[RDavidson]

I have a used Deer Creek Nilai inbound. Thanks tor putting this on my radar newzooreview! If I didn’t come across this, I’d probably have gotten something from Buckeye for around the same price (either NCore X or Purifi). Keeping my fingers crossed, but I’m pretty sure it will work out nicely. I’m optimistic about it. If I don’t like it, for some reason, then that’s probably a good sign I wouldn’t like those aforementioned options either and may need to reconsider my speakers being paired with it. I think my little Dyns will work a treat if my other speakers are less happy with the Nilai. I’ll post my impressions after I’ve had at least a week with it. Wish me luck!

[NIGHTFALL1970]

Cool looking stuff Phil, thanks for sharing that.👍

[danvillesignal]

I have used most of the amplifiers mentioned and our customers have probably used the others. I personally know many of the designers and principals of the companies that make them.
We make 4 channel boxes that use internal Hypex OEM amplifiers that match our dspNexus housings. These are good values, but not quite as good as the best amplifiers previously mentioned.

Modern Class D amplifiers are very good. As a former Class AB amplifier designer with some skill, I was originally surprised.

I am not going to jump into the what amplifier is best, but I did want to make a few tech comments:

• If you need to drive very low impedances, check the manufacturers specs. The load of a class D amplifier affects the amplifier's low pass filtering.
  Some amplifiers that are otherwise quite good may not work well with low impedance loads.
• Speaker loads affect audible performance, cables not so much. 
• In an active system, all amplifiers tend to perform much better since the amplifier has an easier task

Al Clark

[jtsnead]

My journey so far with Class D
I lost my job in 2019 and sold everything I had which was basically tube stuff Rogue, Audio Research, started hearing about really good amps for low money, here is my history:

2009 Virtue Audio small integrated that used a Tripath chip amp later added a tube input buffer, very sweet sounding amp
2010 Audiocircle had a thread about a company out of CA ClassDaudio that hired handicapped people that built class d amp boards for kits, so I built a dual mono amp sounded great for the cost of less than 1K
2015 D Sonic M3-800 mono amps based on Pascal boards I found them a little bright and not involving
2016 Acoustic Imagery Atsah 500 mono amps with Ncore 500 boards very nice sound
2016 Nord One Up mono amps with Ncore 500 boards also heard they had custom input boards that you could change out the op-amps and customize the sound how you like it
2020 Traded Nords on the PS Audio M1200's another nice upgrade everything is just better with tube inputs, very satisfied
2023 Got tired of the hiss from the M1200’s (Ice boards) tube inputs, got the top of the line Orchard Audio Ultra. Very similar to the M1200’s without the hiss and I feel better depth and cleaner highs, great control of low end with good definition

[cheesey]

To be clear, I’m not here to chase specifications or test results. If that was the case I’d just buy whatever ASR says is best and be done. These tests don’t tell me anything about people’s real world experiences however. That’s what I’m most interested in.

With that said, I think virtually all, well-engineered, class D permutations range from good to excellent. Load invariance is nice, but doesn’t really matter when most of these amps can output 200 wpc into 4 ohms continuous. This is more than enough load invariance when I’m only using maybe 1 watt at typical listening levels in my room with my speakers.

Your comment would seem to indicate that you do not understand what load varying frequency response means....It has little to do with the power output, rather, a "flat" frequency response in an amplifier means the amplifier reproduces all frequencies within a specific range (usually 20-20K Hz) at the same amplitude, without any noticeable coloration or amplification of certain frequencies, with changing load impedance. Since most speakers present a varying impedance with frequency, it is desirable to have an amp that produces a flat response independent of the load.

[AllanS]

…it is desirable to have an amp that produces a flat response independent of the load.

Which I understand is a feature of Purifi amps.

[RDavidson]

Your comment would seem to indicate that you do not understand what load varying frequency response means....It has little to do with the power output, rather, a "flat" frequency response in an amplifier means the amplifier reproduces all frequencies within a specific range (usually 20-20K Hz) at the same amplitude, without any noticeable coloration or amplification of certain frequencies, with changing load impedance. Since most speakers present a varying impedance with frequency, it is desirable to have an amp that produces a flat response independent of the load.

Well…power output does matter, right? If all I’m using is 1 watt, but the amp can output 200, then the speaker’s varying impedance matters less to the amp. That’s well understood. But I guess you’re saying that even if said amp is just loafing along that its output at certain frequencies will still vary simply because of a speaker’s varying load? If so, I guess the question becomes : How audible are those frequency aberrations in real world use? I understand they’re not ideal, but if the issue is benign or not even perceptible, then is it really an issue? This is why I don’t like to get too caught up with only judging amplifiers by specs and measurements. Ultimately, if I’m getting sound that I enjoy, then that’s what matters. If the specs and measurements are great too, well then that’s icing on the cake.

[cheesey]

Well…power output does matter, right? If all I’m using is 1 watt, but the amp can output 200, then the speaker’s varying impedance matters less to the amp. That’s well understood. But I guess you’re saying that even if said amp is just loafing along that its output at certain frequencies will still vary simply because of a speaker’s varying load? If so, I guess the question becomes : How audible are those frequency aberrations in real world use? I understand they’re not ideal, but if the issue is benign or not even perceptible, then is it really an issue? This is why I don’t like to get too caught up with only judging amplifiers by specs and measurements. Ultimately, if I’m getting sound that I enjoy, then that’s what matters. If the specs and measurements are great too, well then that’s icing on the cake.

The speaker's impedance varies with frequency, not power.

Whether or not it is audible depends on many factors. Usually people get into hi-fi because they want gear that reproduces the signal with a high level of fidelity. Today there are amps that produce a flat frequency response and low distortion for very reasonable and competitive prices- one can spend much more and not get that performance. If that performance is not important to you for whatever reason, then you can do what many people do and just buy something at Best Buy. Many people after all enjoy the sound from mid fi components. With today's state of the art amplifiers by Purifi, Hypex, and the like, the amp is not the weak link in the reproductive chain- speakers and the room are areas that generally account for more distortion and have a greater impact on the accurate reproduction of the signal. In general, distortion in the system is additive therefore it is best practice to eliminate it where ever possible. Far easier and cheaper to reduce it to inaudible at the amp. Then again, some people like distortion. It becomes a matter of personal preference. You have come here looking for recommendations for something that is a matter of personal preference- never something one can count on and usually a waste of time.

[I.Greyhound Fan]

Nice set up Phil.  I wish I had a pair of the Theils.  I loved the beautiful transparent sound of the 3.7's.

[Phil A]

Nice set up Phil.  I wish I had a pair of the Theils.  I loved the beautiful transparent sound of the 3.7's.

Thx so much.  I've owned a bunch of their speakers.  I started out with 2.3s, probably early 1998 and SCS2s for the center and surrounds (still use SCS2s for the side and rear surrounds).  I have other systems with other speakers.  The speakers in my other pic above are old Selah Audio SA2s (old discussion here - https://www.audiocircle.com/index.php?topic=104414.0) with a Sumiko Audio S.5 subwooofer (which is a copy of a Rel S5 as Sumiko formerly distributed Rel Subwoofers in the US).

I also still have my B&W P6s (original owner and I bought them in 1997) in a spare HT system (and the Atmos height channels behind the TV are Ohm Microwalsh Talls, which I had used where I currently have the Selah Audio SA2s) and a pair of GR Research N3s in my upstairs bonus room (which is basically a guest bedroom).

[RDavidson]

The speaker's impedance varies with frequency, not power.

Whether or not it is audible depends on many factors. Usually people get into hi-fi because they want gear that reproduces the signal with a high level of fidelity. Today there are amps that produce a flat frequency response and low distortion for very reasonable and competitive prices- one can spend much more and not get that performance. If that performance is not important to you for whatever reason, then you can do what many people do and just buy something at Best Buy. Many people after all enjoy the sound from mid fi components. With today's state of the art amplifiers by Purifi, Hypex, and the like, the amp is not the weak link in the reproductive chain- speakers and the room are areas that generally account for more distortion and have a greater impact on the accurate reproduction of the signal. In general, distortion in the system is additive therefore it is best practice to eliminate it where ever possible. Far easier and cheaper to reduce it to inaudible at the amp. Then again, some people like distortion. It becomes a matter of personal preference. You have come here looking for recommendations for something that is a matter of personal preference- never something one can count on and usually a waste of time.

Yes, I am aware that impedance varies with frequency. The only thing I was saying is that these impedance swings shouldn’t be so severe that a good amplifier, of adequate power, should handle those swings. Amplifiers that can’t do so will distort, especially at high output…and eventually shut* down or give up the ghost. Whether those frequency abbreviations (you brought up) are audible or not is another topic, but is applicable to people’s subjective opinions. This information is what I’m most interested in.

That said, I’m sorry that you find my search for subjective opinions on class D a waste of time. As I already stated, if I only cared about objective performance I would buy whatever amplifier is at the top of ASR’s list and wouldn’t have started this thread. I currently own 5 of Nelson Pass’s creations, which I love for their various audible qualities. The only thing I don’t like is their heat dissipation in the summer. In my original post I stated that this is the core reason for my class D search. However we all know that different amps perform differently, including class D amps. So…if someone has experience with class D with speakers that I am familiar with and maybe even has a similar room size, then it would be great to hear from those people (in my case) wouldn’t it? Regardless, I am open to learning from anyone who wishes to contribute to my search.


*  edited by admin on request of author