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Best Class D or cool-running amplifier to try?

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ahofer

ahofer

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Indeed these streaming services are like having access to a large public/university library rather than you own book shelves. I have found it a culturally very rich experience. My only gripe concerns the user interfaces of these services.

yes. I should look for a thread on this subject. I find the search functions balky for classical, and the various lacunae in Qobuz and Tidal availability are a mystery, although somewhat complementary. There is a new all-classical service, Primephonic, that I haven't explored.

On the sound side, I have had a few alarming events where the data was corrupted and sent some pretty harsh signals through my equipment. Most recently playing the LSO hi-res recording of Mahler 1, third movement. First it sent through a few static lightning strikes, then fell silent. Yikes! If they blow my Harbeths there will be hell to pay. Obviously there could be some downstream design issues (Cambridge Edge NQ using Bubble UPnP)
 

Victoria

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Indeed these streaming services are like having access to a large public/university library rather than you own book shelves. I have found it a culturally very rich experience. My only gripe concerns the user interfaces of these services.

Bandcamp fills this particular niche extremely well for me! I can sample entire albums through my web browser and then easily purchase and download anything I like as a simple ZIP file containing all my music in WAV which I then extract and organise within my PC’s filesystem and subsequently copy and paste over to my portable DAP.

My gripes with streaming come when I cannot easily download music offline in a DRM-free format, which seemed to often be the case when I last tried to look into other ways of acquiring music. I’m also cautious of services which require software support for specific standards which may or may not change or even exist anymore in the future.

I typically use my hardware long beyond its supported lifespan (my previous desktop setup lasted me almost a decade, and my previous DAP lasted me almost 15 years).

There are a few other websites I use that follow a similar method of music delivery to Bandcamp, but Bandcamp is by a large margin the service I use the most as I listen to a lot of small-time indie artists for most of the genres of music that I like. My priority has always been to invest in music more than the hardware to play said music :D

And given that my partner is also an artist, I am an extremely strong believer in supporting artists as directly and as much as possible, and Bandcamp does that well!

Edit: Seeing as how we’ve pretty much succeeded in partially derailing this thread I think it would be nice if we slowly move back to the original subject at hand :p
 
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digitalfrost

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I grew up the 90s. I still remember vinyl, I had a walkman with casettes, and of course CDs. But as I was always very much into computers, the first stereo I got from my grandfather was immediately hooked up to my PC.

I have never owned a CD player, because there was no need to.

Once MP3 came on the scene, I started to rip all the things. So it has always been normal for me, to listen to music via my PC and to actually own the files. Streaming services are unnecessary for me, especially since mobile devices have reached 128Gbytes of storage I can take almost my complete music collection with me on the road.

I don't want to be dependent on internet or some service provider to listen to music. Spotify has deleted music that I was listening go, or they only have some ****** live version.

Of important albums, I possess multiple versions. Original CD release, vinyl rip, MSFL remaster, SACD...It's nice to be able to compare via ABX. No service can provide me this. Often they don't even tell you the exact version you're listening to.

Just my 2cts.
 
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ahofer

ahofer

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Well, I agree it's better to own the things you love, but for exploring for new things to love, streaming is pretty awesome.
 
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ahofer

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OK, I've had the March Audio p252 in the system for two days.

I had a bit of a long strange trip comparing it to my old amp (Adcom 5802). When I first connected the March, I was sure I could hear a difference. A bit tighter in the bass, not as smooth in the highs. Was the image not as wide? The soloist seemed a little further back?

This evening I had a chance to A/B them, albeit under less than ideal conditions. Since I had to power them off before reconnecting, there was a bit of a lag between listens, and, of course, I'm getting up from the couch to do it. Just to complicate things, the March reverses the channels, so I had to be careful to connect right channel on my DAC to left channel on the March. I put in a pair of cables with bananas instead of spades, to make it easier. After trying to volume equalize on the music, I started doing it on a 1k test tone. As it happens, the two amps have the same gain, so once I started using the test tone, I realized I didn't have to change the volume at all. Eventually I got the switch down to less than 30 seconds.

The better I got at making the swap, the less I could hear a difference. When I started I was almost sure I could, to my distress. Ninety minutes later I'm pretty sure I would fail a blind test between the two.

On the one hand this is oh-so-predictable. I am pretty convinced, in my head, by the volume of tests that suggest this would be the case. On the other hand, on first blush I started hearing some of the things subjectivists and kilobuck amp designers like to say about Class D. I guess my doubts rule my biases even more than my reasoning!

All in all, it was a weird experience. I'd love to get switchboxes that would allow me to make more immediate comparisons. They'd have to be 1-in to 2-out, XLR and Speaker (with some pop protection?).

It's nice to have a cool amp here in the living room, so I can leave the A/C off and enjoy the music. Also, with only the DAC/Streamer and the little p252, I could get rid of the rack and de-clutter.

Next up, I'm thinking I'll test the Orchard Audio PecanPi against my Cambridge DAC. I'm sure the sound will be fine, but I really like the Cambridge streaming features, including Chromecast built-in.
 

typericey

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Thanks for your report @ahofer. If you can't tell any difference with A/B, that's not a bad thing at all. I guess it just means that both amps are transparent and have distortion below the audible range. The good thing is you can now retire the old Adcom and have a smaller, cooler, more energy efficient amp.

I was about to order the P502 when Alan told me that he ran out! (Will be restocked soon I believe). I couldn't wait and so I got a Rotel instead and am quite happy with it.
 
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ahofer

ahofer

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Thanks for your report @ahofer. If you can't tell any difference with A/B, that's not a bad thing at all. I guess it just means that both amps are transparent and have distortion below the audible range. The good thing is you can now retire the old Adcom and have a smaller, cooler, more energy efficient amp.

I was about to order the P502 when Alan told me that he ran out! (Will be restocked soon I believe). I couldn't wait and so I got a Rotel instead and am quite happy with it.

Yes, I'd love to wax on and on about the ethereal new qualities of music the March amp introduced me to, and slam and PRaT, etc. but I think the only thing I could honestly say I noticed is a very slight difference in bass sound. But sounding the same, for less money than I spent on the Adcom in 1993, using far less power, not acting as a space heater, taking up far less space, weighing 10% of the Adcom, and delivering nearly as much power, that's all a pretty cool achievement of the little nc252mp in Alan's design.

I mean, I bought the Adcom to drive an insanely difficult load (Thiel CS3.6) - it puts out 450 watts at 4 ohms, high s/n and flat response. Nelson Pass design. Simple signal path, high bias. The thing plays for 40 seconds after you power off. It demonstrates all the heavy space heater attributes of audiophile class AB.

BTW, the March does get a little warm.

So Alan, what's with the channel reversal? (left input goes to right speaker). Had me panicked there when the violins burst out of the right side of the stage (and yes, I confirmed this with test tones).
 

typericey

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pjug

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So Alan, what's with the channel reversal? (left input goes to right speaker). Had me panicked there when the violins burst out of the right side of the stage (and yes, I confirmed this with test tones).

Southern hemisphere?
 

Ron Texas

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Nord sent me an email saying they have 20 Purifi modules to be sold at a "premum" as assembled amplifiers. Full production to begin in October.
 
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ahofer

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I posted this in another forum, maybe people here know the answer:
-------

Here are the claims/theories of why Class D sounds different:

-having, effectively, an AM transmitter in your system could have audible effects
-The same high frequency info can cause IM distortion in the audible band, but this measures well below audible levels in specs
-" " could cause odd behavior in tweeter (this seems like BS to me, the energy level would be ridiculously low)
-lots of feedback in a Class D design (not clear that high overall feedback designs have been shown to be audibly different)
-PWM signal sounds qualitatively different


Mostly it is kilobuck amplifier designers who suggest these theories, requiring more than a grain of salt (although the first one is a fairly objectivist speaker designer, Alan Shaw). I just don't know if there is evidence of audibility for any of this. I've seen quite a few blind amplifier tests, but none involving Class D units. Are there any?
 

DonH56

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Could have, can/may/might, all true. Switching frequencies run 400+ kHz or so with harmonics above that. The thing is, they are filtered at the output, and the data I have seen recently shows the switching output spurs to be anywhere from -70 dB to -100 dB or more from full-scale output. So a 100 W class-D amp might put out a 400 kHz spur at 0.00001 W (10 uW) and more likely 10 nW. Your speakers (and everything else) are going to filter that significantly but even if were applied directly to a tweeter, if it can't handle 10 uW of power at 400 kHz (probably won't move, just heat up) I think you've bigger problems. Same for IMD and such. As for feedback, I am against the whole "no feedback" craze. Yes there can be problems when abused, but feedback is what gets you much better performance and amplifiers much more stable over voltage, temperature, aging, etc. variations. I do not miss my old tube amp that sounded way different after a few minutes, different again after an hour or two, and then changed over time as the tubes aged because there was not enough feedback to make the $#@$# thing stable.

There are some real issues with class D, just like there are real issues with class A, AB, etc. amplifiers but the whole "AM transmitter" and "tweeter killer" debates were settled years ago IME/IMO. Modern amplifiers use such a high switching rate that it just isn't an issue. The higher switching rate in turn allows better output filters with less audible impact and more feedback for better performance. The performance of he better, let alone best, class D amplifiers today matches and often exceeds the high-priced conventional designs. And BTW take a look at the 50/60 Hz and 100/120 Hz spurs in some of those kilobuck amplifiers... Sometimes bigger and slower is not better. I'd rather get all that junk out of the audio band.

Not sure on blind tests, hopefully others can chime in.

/rant - Don
 

Victoria

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There are some real issues with class D, just like there are real issues with class A, AB, etc. amplifiers

Amen. I personally give much more credence to issues which I can actually see and measure, and in that respect Class-A fails a lot more check-boxes than Class-D; they're often big, heavy, cost a lot more, and have far too many components in the signal path for my liking. I like to stick to my "the less there is in the signal path the less there is to eff the signal up" mantra. Oh and Class-A amplifiers consume and waste way more power than I am comfortable with and the last thing I need is something that replicates the heat output of a reactor in my living room.

I am considerably biased though because I've been on the Class-D bandwagon for well over a decade but I don't regret a single bit of it. I'm pretty good at convincing myself that I've got the best gear in the world, that in turn saves me a lot of $$$ and allows me to enjoy my music.

Win-win!~
 

geek101

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If you do not need more current than Benchmark AHB2 then stick with it. Get it used and it is close to most well made class D amps in price. I contemplated a lot regarding class D and Benchmark ABH2. Some class A/B and class D amps can put a lot more current if you speakers need it.
 

Daverz

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If you do not need more current than Benchmark AHB2 then stick with it. Get it used and it is close to most well made class D amps in price. I contemplated a lot regarding class D and Benchmark ABH2. Some class A/B and class D amps can put a lot more current if you speakers need it.

I don't think I've ever seen a used ABH2 for sale. Lots of used Benchmark DACs, though.
 

geek101

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I don't think I've ever seen a used ABH2 for sale. Lots of used Benchmark DACs, though.

I am an owner of one, I had the opportunity to buy two of em. You have to check various forums, audiogon, usaudiomart etc. and be patient.
 
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ahofer

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What happened to Amir's test results for the p252 Alan sent him? I thought they were going to be published here or on the March site.
 
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ahofer

ahofer

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Also, to follow up on my Adcom:

New York? And Adcom, then you have a good time reading: https://hoppesbrain.com/

He no longer does any refurbishing. He has no interest in the 5802, in his words:

Thanks, but nope, not a fan of the 5802. Way too troublesome for a number of reasons.
.....
Quality control issues, construction issues, and just plain not enough heatsink for such high idle current. There's a reason Pass Labs amps cost so much.
They do sound great though!
I outline my issues with it here...
https://www.diyaudio.com/forums/solid-state/325618-adcom-gfa-5802-servicing.html#post5569098
 
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