Which class D amplifier would you guys choose?

[Pjetrof]

Behringer A800 budget
apollon signature money no object

 

[Westsounds]

Behringer A800 budget

Great amp I'm sure but it's just a power.

How about an all in one budget option like an integrated ? With a power supply.

How do the real cheap ones stack up like SMSL50 etc. Lowest cost highest performance/cost.

No nasty hiss or pop to speakers when powering on etc.

 

[Webninja]

IOM is another Ncore vendor - https://internetofmusic.nl/shop/
Also March Audio (has a U.K. distributor) - https://www.marchaudio.net.au/

 

[ta240]

...
Also March Audio (has a U.K. distributor) - https://www.marchaudio.net.au/

And they are on sale... which is why I don't carry my credit card with me anymore.

 

[westyjeff]

I chose @March Audio , 1) Form factor. 2) Quality of implementation. 3) He has a lot of trolls (Competition) trying to defend other less than stellar products with overpriced bits (Op amps/Buffers) that do not add any benefit, all while trying to discredit his offerings.

 

[MichaelP]

Recently bought a pair of NC400 based Monoblocks, the Audiophonics version. They are excellent. Interestingly they also have RCA inputs, which wasn’t what was specified on the website — I thought they were XLR only. Bonus flexibility, a welcome surprise.

 

[GuernseyBunker]

Some 1ET400A amps... cut and past from another thread, but relevant perhaps...
https://www.audiosciencereview.com/...mplifier-sonic-shootout-€820-to-€8-344.14048/

PURIFI AUDIO EVAL1 KIT* (DKK4,775) £640 + *PSU = £820
https://purifi-audio.com/vare/eval1/. *PSU required (i.e Hypex SMPS1200A400 = £180)

VTV Purifi 1ET400A Stereo = (US$959) = £852
https://vtvamplifier.com/product/vtv-amplifier-stereo-purifi-audio-1et400a-amplifier/

NORD THREE 1ET400A ST Stereo Amplifier = £1,099 ex VAT
https://www.nordacoustics.co.uk/product-page/nord-three-1et400a-stereo-amplifier-1

AUDIOPHONICS LPA-S400ET (€1,349) = €1,124 ex VAT
https://www.audiophonics.fr/en/powe...eo-amplifier-purifi-2x400w-4-ohm-p-14557.html

NORD THREE 1ET400A Mono Block £625 X 2 = €1,250 ex VAT
https://www.nordacoustics.co.uk/product-page/nord-three-1et400a-stereo-amplifier

AUDIOPHONICS HPA-S400ET (€1,490) = €1,241 ex VAT
https://www.audiophonics.fr/en/powe...4393.html?search_query=iet400a&fast_search=fs

NORD THREE SE 1ET400A MKII Dual Mono Stereo Amp = £1,649 ex VAT
https://www.nordacoustics.co.uk/product-page/nord-three-se-1et400a-dual-mono-stereo-amp

NORD THREE SE 1ET400 MKII Mono Block Single (£850) X 2 = €1,700 ex VAT
https://www.nordacoustics.co.uk/product-page/nord-three-se-1et400-mkii-mono-block-single

APOLLON PURIFI 1ET400A BASED STEREO AMPLIFIER €2,280 ex VAT
https://www.apollonaudio.com/apollon-audio-purifi-1et400a-stereo-amplifier-input-buffer-board/

MARCH AUDIO P451 Mono Block Power Amplifier (US$1,295) €1,150 x 2 = €2,300
https://www.marchaudio.net.au/product-page/p451-mono-block-power-amplifier

ROUGE Alauda MB5 @ €1,155.00 x 2 = €2,310 ex VAT
https://en.rougeaudiodesign.com/product-page/alauda-mb-5

APOLLON PURIFI 1ET400A BASED MONO BLOCK AMPLIFIER = €1,190 X 2 = €2,380 ex VAT
https://www.apollonaudio.com/purifi-1et400a-apollon-audio-monoblock/

ATM AUDIO EPM3P Mono €1,400 x 2 = €2,800 ex VAT
https://atm-audio.com/product/epm3p/

NAD M33 = €3,999
https://nadelectronics.com/m33/

ATM AUDIO EPM-450 STEREO = €5,695 ex VAT
https://atm-audio.com/product/epm-450-stereo/

BEL CANTO E1X AMPLIFIER (£5,600) = €6,240
https://belcantodesign.com/home/e1x/e1x-amplifier/ (1ET400A architecture to be verified)

ATM AUDIO EPM-450 €4,172 X 2 = €8,344
https://atm-audio.com/product/epm-450-mono/

LKV RESEARCH VEROS PWR+ POWER AMPLIFIER = € TBA
https://www.lkvresearch.com/lkv-veros-power-plus.html

VERA AUDIO P150/600 AMPLIFIER = € TBA
https://www.vera-audio.com/newsarticle.php?news_id=3

 

[maxp779]

Well I ended up saying screw the budget and getting 2x Nord Purifi 1ET400A monoblocks Sound great so far, run cool, easy to place, very aesthetic. I'll maybe make a video review of them, I plan to keep these things for a long long time.

 

[GuernseyBunker]

Well I ended up saying screw the budget and getting 2x Nord Purifi 1ET400A monoblocks Sound great so far, run cool, easy to place, very aesthetic. I'll maybe make a video review of them, I plan to keep these things for a long long time.

Amazing maxp779 - I cobbled together the 1ET400A amp thread (above) and did the very same thing (2 x Nord Purifi ET400A monoblocks) as you.

I have to say, in addition to Nord's unswerving dedication to the evolution of their already stellar catalogue of products, being able to pick up the phone and actually talk to the guru himself (Colin North) is an extraordinary concession at a time when it seems many others are running at full speed to hide their service, support and production facilities deep behind a firewall of internet contact forms, email networks, unhelpful FAQ page referrals and marketing gloss.

Well done and congratulations on an absolutely perfect Nord system

 

[jd3]

I have a Channel Islands Audio C 100S that is Hypex based. It's a really good performing amp.

I also recently received a March Audio P502. Alan answered all my questions and I finally ordered it on April 29. I was expecting shipping about a week later when Alan contacted me to tell me that the module was not performing up to specs, so he wouldn't send it to me. Unfortunately he didn't have other modules in stock so had to order one, and due to COVID, it took longer than normal for him to receive it. Ultimately it took 45 days to receive the amp, but I appreciated that Alan had tested the original amp before sending it to me. I'm not sure what the issue was (and I may never have even noticed it) but Alan made sure to send me a unit that was 100% functional. I like the form factor and functionality (especially the front on/off switch). Oh, and it sounds great. Lots more power than my CIAudio amp.

As an aside I've owned ICE based amps in the past and to me, the Hypex based amps are much better sounding. I've owned a bunch of class A and A/B amps and I'll never go back. The size, weight, performance, and relative affordability of Class D vs 'traditional amps' tilt the scale for me to the Class D side.

 

[Kegemusha]

I would add 2 more to that list, the XTZ Edge a2 300 and some with the purifi module like this one maybe.
The XTZ can be found sometimes at 350 Euros new, for that price is a good contender I think.

 

[Pjetrof]

None.

Can you explain why pls?

 

[Puska]

So im trying to figure out which class D amplifier to go for... I've been looking at these since im UK based:

Audophonics have a 2x NC500MP amp:
https://www.audiophonics.fr/en/powe...s-d-amplifier-2x500w-4-ohm-ncore-p-13344.html
I gather that with the MP modules the power supplies are built into the module. So the modules are mains powered, hence the MP.

Nord have a 2x NC500 amp with 1 separate power supply:
https://www.nordacoustics.co.uk/product-page/nord-one-nc500st-stereo-amplifier
Looks like NC500's need their own power supply.
They also have the same thing but where each of the modules has their own power supply and do not share one:
https://www.nordacoustics.co.uk/product-page/nord-one-nc500dmst
I have no idea what the benefit of this is...

Nord also have this NC502MP amp:
https://www.nordacoustics.co.uk/product-page/nord-one-se-mp-nc500-stereo-power-amp-in-silver
So the module both has it's own power supply and it is stereo so theres no need for 2 x mono modules.

I mean less circuitry is typically better since there are less things that can fail, less power, less heat. So the 502MP seems pretty good from that point of view. However I suppose it highly depends on the circuitry itself.

It has taken me a substantial amount of time to figure out the differences between all these amplifiers. It's been kinda fun researching it all though But im coming up short when it comes to the actual practical differences between these setups. Apart from cost and the case they come in. What would you guys go for? Or are there other options I haven't considered?

Im in the UK and was looking to spend maybe 900GBP, slightly flexible on this. I saw some people raving about Purifi modules but im certain I couldn't tell the difference and they're quite a bit more expensive than ncore based stuff.

I saw this youtuber. Is he right about the sound?

 

[VintageFlanker]

Is he right about the sound?

Of course, he is not. This guy burn-in his amps and doesn't believe in measurments... Put the NC500 in a giant goldish enclosure, tell him it's class A and he will love it. He can't love these since he KNOWS it's class D. That's one of the most biased "review" I've ever seen.

Hum, "in a giant goldish enclosure"... Wait a minute...

Silver/Gold finish? Copper on the back? Hum, It must sound kind of warmish for sure! Oops! NCore NC500 inside!

Back to the OP. I pulled the trigger on the new Purifi Mini from @Apollon Audio. I don't need the tremendous power of my AS1200, which I could put on sale soon.

 

[Boomer Bill]

Hello Audio DIYers. Here is an account of my experience with the new Purifi Audio (of Denmark) EVAL 1 package which far exceeds any amp in my experience and is getting sensational reviews in the Audio press. I've purchased two so far and don't see how I can settle for anything less, having heard the rascal play. You need to build a power supply for it, but that should be simple for DIYers. It's been two weeks since I got the first one running. I plan to buy 5 more as I have multiple systems in my home and intend to replace all the power amps.

Adventures in Class D (for Denmark) Land by BoomerBillOne

Dear Stereo Pals! I recently sent off to Purifi Audio Denmark for an engineering model (EVAL1. two power modules and a front end to give the amp 27dB of gain.) of a supposedly "best ever" Class D amp. This unit is designed for evaluation by manufacturers for use in their own products. These days, many companies are using somebody else's power amp modules in their gear. They will also sell to DIY hobbyists, like me. It costs about $850 depending on the exchange rate on the day you purchase. It does not come with a power supply. You've got to build your own. It needs +/- 65 volts, +/- 18 volts, and +15 volts with its negative side tied to the -65 volt line. My first attempt failed and I was afraid I might have damaged the amp. I didn't.

A reviewer, Stuart Aniger, wrote in "Audio Express,' July 2020: " The amplifier did exactly what is supposed to do, noiselessly, without stress or strain, and in a perfectly transparent way."

It's been playing now, loudly for me, for about an hour and it sounds quite good and runs at room temperature. The efficiency of Class D is one of its principal attractions. Its switching frequency is 500 KHz (a competitor, Orchard Audio uses a switching frequency of 700 KHz in its BOSC monoblocks!). Just hold an AM radio near the amp and you'll know it's true! The distortions or errors the amp makes are ALL below -115 dB. At 20 watts, its harmonic distortion at 1000 Hz is below 0.001%. It's still early in its operating life here, but it sure sounds clean as the whistle of a Louisiana Lesser Catbird! I must say that the applause which is part of one of my test tracks (Loreena McKennitt, The Mystic's Dream) was a group of individual hand claps, not a puddle of stacotto noise! I'll run it for the rest of the week to break it in and then compare it to my favorite amp, the EleKit TU8600R. Yikes! One of ace test tunes (Jennifer Warnes, "Joan of Arc," Famous Blue Raincoat 20th Anniversary album) just came on and I have never heard it so distinctly. I had to stop writing and just pay attention. Impressive! Wow! (Speakers are the Golden Ear Trident 1's.)

Of course, the efficiency angle doesn't carry much weight when your favorite amp is a Class A, 8 wpc tube job pulling 90 watts from the power line. I'll measure this amps power draw tomorrow. I don't want to shut it off right now. It's playing another demo piece with lots of pop and complex vocals. I'm going to have to run it with my Shahanian Obelisks someday soon. (The Trident 1's are better.)

Photos show the amp, the power supply, and them running together. The Power supply is keeping the amp from being pulled off the shelf by the speaker cables.

Second Day of Listening to the Eval 1 by Purifi Audio of Denmark

Lori Leibermn - "The Girl And The Cat" - Remarkable clarity. Great piano sound.
The Kenny Rankin Album - Lush!
anything and everything else - Oh my, that’s interesting! Wow!

You’ve heard of Hypex and the nCore amp modules, used in many commercial amps, NAD among them. Bruno Putzeys designed them and joined up with Lars Risbo, then, the ace designers & developers of Class D amps joined with Kim Madsen and Claus Neesgaard to form Purifi Audio and decided they would solve the most vexing problems in audio. They are doing very well at it!

The 1ET400A Class D module, an output “power amp” with a gain of only 13 dB (remind you of anybody else’s low gain/outstanding performance amps?), an output of 400 watts at 4 ohms (that’s different!), 25 amps of output current available, neglible distortion and noise of any kind, and an output impedance too low to measure (it’s in micro Ohms!). It will not have trouble driving ANY speaker and will not interact in ways that cause its output frequency response or distortion products to vary in any noticable way. Odd crossovers and speaker impedance shifts with frequency will not phase it. (No pun intended.) Not bad! And they are working on “high voltage” modules that will produce 1 and 2 Kilowatts (!) of power at up to 40 amps of output current. And they have a very interesting 6.5 inch mid/woofer with outstanding performance if you have an extra $350 in the bank.

One consequence of the behavior (or lack of it) of this amp is that if a speaker is capable of sounding good, it will. But, if something is not right, it will be obvious! I tried three different speakers of good reputation and was stunned to hear them sounding very similar. I tried a DIY speaker I was very proud of and discovered that something was terribly wrong with the crossover. The Milk Carton Kids sounded like they were stuck in the milk carton itself. I thought I had obtained 85% of the performance of the Raidho D1; not with that crossover, fella! Why did that flaw not show up with ever other amp I have on hand? I wish I knew. An hour of woofer crossover coil changes solved the problem, but wow, the good stuff tells the truth whether you wanted it to or not.

I haven’t found any data on the “damping factor” of the amp. It must be enormous. You’ve heard about “tight bass” being a selling point for solid state amps. The amp doesn’t just push a speaker’s vibrating element forward, it also pulls it back. High amounts of feedback allows the amp to tightly control the speaker, but it lowers the amp’s gain. A well designed amp can tell the difference between the speaker’s actual motion and what the amp told it to do. Such an amp can produce an “error correcting” signal to encourage the speaker to behave properly in real time. (Some amp designers feel the speaker’s behavior is not his problem. That sort of thing is the speaker designer’s problem, not his. Those amp are the ones that “sound best with speakers from X, Y, and Z Labs.”) At only 13 dB of gain, you can see the amp is using a lot of feedback, but it pays big dividends in speaker control. And it can put out 25 amps of current! (Assuming the power supply is capable of supplying it.)

The efficiency is remarkable. Playing it loudly, the amp pulls less than 18 watts from the power line. Its idling power drain is just over 16 watts. Playing the big number from Handel's Messiah, it pulls less than 20 watts (using Triton One speaker from Golden Ear. Even using four inch coaxial, 85 dB sensitive speakers, I couldn’t get the amp to draw 20 watts at a level I feared would damage the speakers.). I have meters on the three power supplies; they never move. So here is a big clue; the power supply is not strained and/or its fluctuations are so brief so as not to make the needle move and/or having 120,000 microfarads of capacitors on the high voltage power supply helps a lot! The 4 amp fast blow fuse has not blown yet. Also, it’s likely that this amp will not need fancy power cables. But opinions differ.

With no input, the amp is dead silent. That’s where “blacker blacks” come from. If the EVAL1 package is still available from Purifi Audio when you read this, realize you can build a power supply and have this amp running in your system for about $1000. If you you want a fancy cabinet, that’s extra. I don’t care how it looks, I only care how it sounds. If you have free roaming pets or small kids, a cabinet is mandatory. I started writing this on a Wednesday morning and it’s now late Friday afternoon. On Sunday, I’ll compare it to my wonderful Elekit TU8600R tube amp and see what happens to its sweet delicacy.

Sunday came and dusk approaches. The testing is concluded. Well, it’s over; the results are in and the results are clear. First Prize goes to the Purifi Audio EVAL1 package. It’s clearer, cleaner, more defined, more transparent than anything I have in the house, certainly; and the best I have listened to. It presents music in a more “natural” way; which seems an odd thing to say about a Class D amplifier. But we pay to view movies at 24 frames per second; we happily watch TV at 30 frames per second; so why should seem odd to hear music sampled at half a million times per second. CDs give us music sampled at less than a tenth of that. And it only costs us less than a forth of the electrical power that a 300B tube using. 9 wpc, Class A stereo amp pulls from the wall. My charming, beloved, ever so sweet, non-fatiguing nine watter pulls 88.9 watts; the Danish Wonder pulls not even twenty under normal conditions. The wattmeter may not be able to indicate the very rapid fluctuations in the amps power consumption.

The difference is most obvious when listening to the background or harmony vocals sung by the same performer who sings the melody lines in a studio production. You know it’s the same performer in the same booth, on a different “take,” but with the volume cut down 10 db or so. But there they stand, in three dimensions, breathing like a real person, not a paper cutout - a twin. You can’t tell what their hair color is, or what perfume the ladies are wearing, but just about everything else.

Tiny metallic transients are more than clicks that seem somehow to have a pitch. No, they are chimes of very short duration. There is music there, not just percussion. Also, the tape hiss, which I never noticed before, is clearly audible on certain older recordings. No doubt, that’s because the Purifi Audio amp is virtually noise and distortion free.

This module, the 1ET400A, is currently used in some production amps selling for $5000 (NAD M33) and up, WAY UP. But, if you hurry, you just may be able to get a pair of them, along with a suitable - gain increasing - protecting - totally compatible front end with connecting (balanced input, banana output) sockets for around a fifth of that, including your DIY power supply. You’ll find them at www.Purifi-audio.com.

The right channel of the Eval 1 protection circuits kicked in about 5 PM. August 12, 2020. I don’t know why. The right channel’s “OK” light did not light and the output was silent. I turned it on and off a few times waiting a minute or so between tries. Nope! I wore black PJs to bed that night.

I was going to order a pair of Maggie LRS speakers to run with it. Alas!

Just for “old times sake” I turned on the EVAL 1 the next morning; it worked! Happy day! God answers the prayers of His audio enthusiast followers. Halleluah! Then it occurred to me that I had put 120,000 mfd. of filter capacitors on the high voltage (+/- 63v) power supply, 60,000 mfd on the op amp power supply ( +/- 20v) and 10,000 mfd. on the gate supply (15v) - so - the error detecting cicuits, once triggered, would not reset until the power supplies had died out completely. That takes a looooong time. The amp has an “enable operation” switch, not really a power switch. My power supply has a switch that disconnects it from the AC power line but does nothing to dissapate the energy stored in the filter capacitors. My power supply has LEDs and meters on the three sections, but it still takes a while (I just went to time it - I got tired of waiting at ten minutes) for the voltages to drop low enough for the circuitry to reset. The high voltage light is still on with 30 volts or so and the lights are finally off on the lower voltage supplies, 2 volts or less. Purifi Audio suggests leaving the amp powered up all the time since the power drain at idle is only a watt or so. I’m a belt and suspender kind of guy, so I turn the power supply off. I’m in Southern California. We get power surges that make the bathroom nightlight scorch the paint on the wall. No Kidding!

Well, from my point of view, since you can build the power supply for $150 or so and get the EVAL 1 for about $850, you can have the best stereo power amp available for $1000. I’m ordering another one. And a set of Magnepan LRS to go with it. Ain’t life grand? Keep smiling!

The Stereophile Magazine, September 2020, contains a rave review of the $10,000 LKV Veros PWR+ power amp. It uses the Purifi Audio 1ET400A modules. It impressed reviewer Herb Reichert as being “a remarkable balance between analytical and romantic . . . sounded more Class A than Class D . . . played equally rich atmosphere - soaked through the entire audio band. It did atmospheric dreamy like Class A does atmospheric dreamy. Surprising and impressive.” Curiously, the same issue praises my favorite tube amp, the Elekit TU8600R as ” . . . ambiance sensing . . . expos(ing) the unique forms and harmonic spectra of the individual notes.” But the Purifi modules do it even better. Compared with another, well regarded, Class D amp - the Bel Canto REF600M; ”the LKV rendered berimbau (a Brazillian instrument) with a more complex palette of overtones and showed infinite variation in string attack. . . . soundstage depth was dramatically deep. What the LKV was doing seemed inexplicable. . . . (its) sound like limitless, sensual, tactile, luxury Class A watts.” Italics are the author’s, the parenthsis & capitalizations, mine. The final words in the review T400A modules remove the clear greeting card plastic wrapper our recorded music comes in. You know, the one that says, “This music was recorded for your enjoyment at this time.” You just hear the music as it was being played at the time.

Please allow me to repeat and earlier paragraph for all the DIY folks out there. Well, from my point of view, since you can build the power supply for $150 or so and get the EVAL 1 for about $850, you can have the best stereo power amp available for $1000. I’m ordering another one. And a set of Magnepan LRS to go with it. Ain’t life grand? Keep smiling!

Friends, we can get a discount (about 5%) if we can put together an order for four EVAL 1 packages from Purifi Audio in Denmark. It will arrive in way less than a week; they ship by Air DHL (mine came 3 days after placing the order). Contact me at [email protected] and join (it’s free) the DIY oriented Ventura County Audio Society - today!

P.S. I’ll set up tables in back yard and we can have a power supply building party!

 

[brodie_mc_choad]

Behringer A800 budget
apollon signature money no object

I've made repeated offers to Amir to test the following:

ICE Power 1200AS2 totally standalone with extra thick gauge power supply cable

PS Audio ICE Power based Mono things based on the 700 series IP modules

DIY Hypex dual NC500 with stock input buffer boards ( compared with various others incl. Sparkos and the audile difference is nonsense to bullshit)

Hypex NC502MP which is just a board with connections like the ICE Power AS2 and inputs/outputs (my personal favorite with no measurements and no fucking way it's ever reached even 500W combined power given the circuit it's on).

But the first one in the list is almost exactly the Apollon, which he must have gotten a great deal on in bulk to be able to sell for how much he does with any sort of markup at all. I got mine from a nut up in New Jersey that AFAIK is out of the business now.

 

[brodie_mc_choad]

Hello Audio DIYers. Here is an account of my experience with the new Purifi Audio (of Denmark) EVAL 1 package which far exceeds any amp in my experience and is getting sensational reviews in the Audio press. I've purchased two so far and don't see how I can settle for anything less, having heard the rascal play. You need to build a power supply for it, but that should be simple for DIYers. It's been two weeks since I got the first one running. I plan to buy 5 more as I have multiple systems in my home and intend to replace all the power amps.

Adventures in Class D (for Denmark) Land by BoomerBillOne

Dear Stereo Pals! I recently sent off to Purifi Audio Denmark for an engineering model (EVAL1. two power modules and a front end to give the amp 27dB of gain.) of a supposedly "best ever" Class D amp. This unit is designed for evaluation by manufacturers for use in their own products. These days, many companies are using somebody else's power amp modules in their gear. They will also sell to DIY hobbyists, like me. It costs about $850 depending on the exchange rate on the day you purchase. It does not come with a power supply. You've got to build your own. It needs +/- 65 volts, +/- 18 volts, and +15 volts with its negative side tied to the -65 volt line. My first attempt failed and I was afraid I might have damaged the amp. I didn't.

A reviewer, Stuart Aniger, wrote in "Audio Express,' July 2020: " The amplifier did exactly what is supposed to do, noiselessly, without stress or strain, and in a perfectly transparent way."

It's been playing now, loudly for me, for about an hour and it sounds quite good and runs at room temperature. The efficiency of Class D is one of its principal attractions. Its switching frequency is 500 KHz (a competitor, Orchard Audio uses a switching frequency of 700 KHz in its BOSC monoblocks!). Just hold an AM radio near the amp and you'll know it's true! The distortions or errors the amp makes are ALL below -115 dB. At 20 watts, its harmonic distortion at 1000 Hz is below 0.001%. It's still early in its operating life here, but it sure sounds clean as the whistle of a Louisiana Lesser Catbird! I must say that the applause which is part of one of my test tracks (Loreena McKennitt, The Mystic's Dream) was a group of individual hand claps, not a puddle of stacotto noise! I'll run it for the rest of the week to break it in and then compare it to my favorite amp, the EleKit TU8600R. Yikes! One of ace test tunes (Jennifer Warnes, "Joan of Arc," Famous Blue Raincoat 20th Anniversary album) just came on and I have never heard it so distinctly. I had to stop writing and just pay attention. Impressive! Wow! (Speakers are the Golden Ear Trident 1's.)

Of course, the efficiency angle doesn't carry much weight when your favorite amp is a Class A, 8 wpc tube job pulling 90 watts from the power line. I'll measure this amps power draw tomorrow. I don't want to shut it off right now. It's playing another demo piece with lots of pop and complex vocals. I'm going to have to run it with my Shahanian Obelisks someday soon. (The Trident 1's are better.)

Photos show the amp, the power supply, and them running together. The Power supply is keeping the amp from being pulled off the shelf by the speaker cables.

Second Day of Listening to the Eval 1 by Purifi Audio of Denmark

Lori Leibermn - "The Girl And The Cat" - Remarkable clarity. Great piano sound.
The Kenny Rankin Album - Lush!
anything and everything else - Oh my, that’s interesting! Wow!

You’ve heard of Hypex and the nCore amp modules, used in many commercial amps, NAD among them. Bruno Putzeys designed them and joined up with Lars Risbo, then, the ace designers & developers of Class D amps joined with Kim Madsen and Claus Neesgaard to form Purifi Audio and decided they would solve the most vexing problems in audio. They are doing very well at it!

The 1ET400A Class D module, an output “power amp” with a gain of only 13 dB (remind you of anybody else’s low gain/outstanding performance amps?), an output of 400 watts at 4 ohms (that’s different!), 25 amps of output current available, neglible distortion and noise of any kind, and an output impedance too low to measure (it’s in micro Ohms!). It will not have trouble driving ANY speaker and will not interact in ways that cause its output frequency response or distortion products to vary in any noticable way. Odd crossovers and speaker impedance shifts with frequency will not phase it. (No pun intended.) Not bad! And they are working on “high voltage” modules that will produce 1 and 2 Kilowatts (!) of power at up to 40 amps of output current. And they have a very interesting 6.5 inch mid/woofer with outstanding performance if you have an extra $350 in the bank.

One consequence of the behavior (or lack of it) of this amp is that if a speaker is capable of sounding good, it will. But, if something is not right, it will be obvious! I tried three different speakers of good reputation and was stunned to hear them sounding very similar. I tried a DIY speaker I was very proud of and discovered that something was terribly wrong with the crossover. The Milk Carton Kids sounded like they were stuck in the milk carton itself. I thought I had obtained 85% of the performance of the Raidho D1; not with that crossover, fella! Why did that flaw not show up with ever other amp I have on hand? I wish I knew. An hour of woofer crossover coil changes solved the problem, but wow, the good stuff tells the truth whether you wanted it to or not.

I haven’t found any data on the “damping factor” of the amp. It must be enormous. You’ve heard about “tight bass” being a selling point for solid state amps. The amp doesn’t just push a speaker’s vibrating element forward, it also pulls it back. High amounts of feedback allows the amp to tightly control the speaker, but it lowers the amp’s gain. A well designed amp can tell the difference between the speaker’s actual motion and what the amp told it to do. Such an amp can produce an “error correcting” signal to encourage the speaker to behave properly in real time. (Some amp designers feel the speaker’s behavior is not his problem. That sort of thing is the speaker designer’s problem, not his. Those amp are the ones that “sound best with speakers from X, Y, and Z Labs.”) At only 13 dB of gain, you can see the amp is using a lot of feedback, but it pays big dividends in speaker control. And it can put out 25 amps of current! (Assuming the power supply is capable of supplying it.)

The efficiency is remarkable. Playing it loudly, the amp pulls less than 18 watts from the power line. Its idling power drain is just over 16 watts. Playing the big number from Handel's Messiah, it pulls less than 20 watts (using Triton One speaker from Golden Ear. Even using four inch coaxial, 85 dB sensitive speakers, I couldn’t get the amp to draw 20 watts at a level I feared would damage the speakers.). I have meters on the three power supplies; they never move. So here is a big clue; the power supply is not strained and/or its fluctuations are so brief so as not to make the needle move and/or having 120,000 microfarads of capacitors on the high voltage power supply helps a lot! The 4 amp fast blow fuse has not blown yet. Also, it’s likely that this amp will not need fancy power cables. But opinions differ.

With no input, the amp is dead silent. That’s where “blacker blacks” come from. If the EVAL1 package is still available from Purifi Audio when you read this, realize you can build a power supply and have this amp running in your system for about $1000. If you you want a fancy cabinet, that’s extra. I don’t care how it looks, I only care how it sounds. If you have free roaming pets or small kids, a cabinet is mandatory. I started writing this on a Wednesday morning and it’s now late Friday afternoon. On Sunday, I’ll compare it to my wonderful Elekit TU8600R tube amp and see what happens to its sweet delicacy.

Sunday came and dusk approaches. The testing is concluded. Well, it’s over; the results are in and the results are clear. First Prize goes to the Purifi Audio EVAL1 package. It’s clearer, cleaner, more defined, more transparent than anything I have in the house, certainly; and the best I have listened to. It presents music in a more “natural” way; which seems an odd thing to say about a Class D amplifier. But we pay to view movies at 24 frames per second; we happily watch TV at 30 frames per second; so why should seem odd to hear music sampled at half a million times per second. CDs give us music sampled at less than a tenth of that. And it only costs us less than a forth of the electrical power that a 300B tube using. 9 wpc, Class A stereo amp pulls from the wall. My charming, beloved, ever so sweet, non-fatiguing nine watter pulls 88.9 watts; the Danish Wonder pulls not even twenty under normal conditions. The wattmeter may not be able to indicate the very rapid fluctuations in the amps power consumption.

The difference is most obvious when listening to the background or harmony vocals sung by the same performer who sings the melody lines in a studio production. You know it’s the same performer in the same booth, on a different “take,” but with the volume cut down 10 db or so. But there they stand, in three dimensions, breathing like a real person, not a paper cutout - a twin. You can’t tell what their hair color is, or what perfume the ladies are wearing, but just about everything else.

Tiny metallic transients are more than clicks that seem somehow to have a pitch. No, they are chimes of very short duration. There is music there, not just percussion. Also, the tape hiss, which I never noticed before, is clearly audible on certain older recordings. No doubt, that’s because the Purifi Audio amp is virtually noise and distortion free.

This module, the 1ET400A, is currently used in some production amps selling for $5000 (NAD M33) and up, WAY UP. But, if you hurry, you just may be able to get a pair of them, along with a suitable - gain increasing - protecting - totally compatible front end with connecting (balanced input, banana output) sockets for around a fifth of that, including your DIY power supply. You’ll find them at www.Purifi-audio.com.

The right channel of the Eval 1 protection circuits kicked in about 5 PM. August 12, 2020. I don’t know why. The right channel’s “OK” light did not light and the output was silent. I turned it on and off a few times waiting a minute or so between tries. Nope! I wore black PJs to bed that night.

I was going to order a pair of Maggie LRS speakers to run with it. Alas!

Just for “old times sake” I turned on the EVAL 1 the next morning; it worked! Happy day! God answers the prayers of His audio enthusiast followers. Halleluah! Then it occurred to me that I had put 120,000 mfd. of filter capacitors on the high voltage (+/- 63v) power supply, 60,000 mfd on the op amp power supply ( +/- 20v) and 10,000 mfd. on the gate supply (15v) - so - the error detecting cicuits, once triggered, would not reset until the power supplies had died out completely. That takes a looooong time. The amp has an “enable operation” switch, not really a power switch. My power supply has a switch that disconnects it from the AC power line but does nothing to dissapate the energy stored in the filter capacitors. My power supply has LEDs and meters on the three sections, but it still takes a while (I just went to time it - I got tired of waiting at ten minutes) for the voltages to drop low enough for the circuitry to reset. The high voltage light is still on with 30 volts or so and the lights are finally off on the lower voltage supplies, 2 volts or less. Purifi Audio suggests leaving the amp powered up all the time since the power drain at idle is only a watt or so. I’m a belt and suspender kind of guy, so I turn the power supply off. I’m in Southern California. We get power surges that make the bathroom nightlight scorch the paint on the wall. No Kidding!

Well, from my point of view, since you can build the power supply for $150 or so and get the EVAL 1 for about $850, you can have the best stereo power amp available for $1000. I’m ordering another one. And a set of Magnepan LRS to go with it. Ain’t life grand? Keep smiling!

The Stereophile Magazine, September 2020, contains a rave review of the $10,000 LKV Veros PWR+ power amp. It uses the Purifi Audio 1ET400A modules. It impressed reviewer Herb Reichert as being “a remarkable balance between analytical and romantic . . . sounded more Class A than Class D . . . played equally rich atmosphere - soaked through the entire audio band. It did atmospheric dreamy like Class A does atmospheric dreamy. Surprising and impressive.” Curiously, the same issue praises my favorite tube amp, the Elekit TU8600R as ” . . . ambiance sensing . . . expos(ing) the unique forms and harmonic spectra of the individual notes.” But the Purifi modules do it even better. Compared with another, well regarded, Class D amp - the Bel Canto REF600M; ”the LKV rendered berimbau (a Brazillian instrument) with a more complex palette of overtones and showed infinite variation in string attack. . . . soundstage depth was dramatically deep. What the LKV was doing seemed inexplicable. . . . (its) sound like limitless, sensual, tactile, luxury Class A watts.” Italics are the author’s, the parenthsis & capitalizations, mine. The final words in the review T400A modules remove the clear greeting card plastic wrapper our recorded music comes in. You know, the one that says, “This music was recorded for your enjoyment at this time.” You just hear the music as it was being played at the time.

Please allow me to repeat and earlier paragraph for all the DIY folks out there. Well, from my point of view, since you can build the power supply for $150 or so and get the EVAL 1 for about $850, you can have the best stereo power amp available for $1000. I’m ordering another one. And a set of Magnepan LRS to go with it. Ain’t life grand? Keep smiling!

Friends, we can get a discount (about 5%) if we can put together an order for four EVAL 1 packages from Purifi Audio in Denmark. It will arrive in way less than a week; they ship by Air DHL (mine came 3 days after placing the order). Contact me at [email protected] and join (it’s free) the DIY oriented Ventura County Audio Society - today!

P.S. I’ll set up tables in back yard and we can have a power supply building party!

JFC I'll print this and read it on the shitter over the next few days. Get back to you then.

 

[Vasr]

Hello Audio DIYers. Here is an account of my experience with the new Purifi Audio (of Denmark) EVAL 1 package which far exceeds any amp in my experience and is getting sensational reviews in the Audio press. I've purchased two so far and don't see how I can settle for anything less, having heard the rascal play. You need to build a power supply for it, but that should be simple for DIYers. It's been two weeks since I got the first one running. I plan to buy 5 more as I have multiple systems in my home and intend to replace all the power amps.

Adventures in Class D (for Denmark) Land by BoomerBillOne

Dear Stereo Pals! I recently sent off to Purifi Audio Denmark for an engineering model (EVAL1. two power modules and a front end to give the amp 27dB of gain.) of a supposedly "best ever" Class D amp. This unit is designed for evaluation by manufacturers for use in their own products. These days, many companies are using somebody else's power amp modules in their gear. They will also sell to DIY hobbyists, like me. It costs about $850 depending on the exchange rate on the day you purchase. It does not come with a power supply. You've got to build your own. It needs +/- 65 volts, +/- 18 volts, and +15 volts with its negative side tied to the -65 volt line. My first attempt failed and I was afraid I might have damaged the amp. I didn't.

A reviewer, Stuart Aniger, wrote in "Audio Express,' July 2020: " The amplifier did exactly what is supposed to do, noiselessly, without stress or strain, and in a perfectly transparent way."

It's been playing now, loudly for me, for about an hour and it sounds quite good and runs at room temperature. The efficiency of Class D is one of its principal attractions. Its switching frequency is 500 KHz (a competitor, Orchard Audio uses a switching frequency of 700 KHz in its BOSC monoblocks!). Just hold an AM radio near the amp and you'll know it's true! The distortions or errors the amp makes are ALL below -115 dB. At 20 watts, its harmonic distortion at 1000 Hz is below 0.001%. It's still early in its operating life here, but it sure sounds clean as the whistle of a Louisiana Lesser Catbird! I must say that the applause which is part of one of my test tracks (Loreena McKennitt, The Mystic's Dream) was a group of individual hand claps, not a puddle of stacotto noise! I'll run it for the rest of the week to break it in and then compare it to my favorite amp, the EleKit TU8600R. Yikes! One of ace test tunes (Jennifer Warnes, "Joan of Arc," Famous Blue Raincoat 20th Anniversary album) just came on and I have never heard it so distinctly. I had to stop writing and just pay attention. Impressive! Wow! (Speakers are the Golden Ear Trident 1's.)

Of course, the efficiency angle doesn't carry much weight when your favorite amp is a Class A, 8 wpc tube job pulling 90 watts from the power line. I'll measure this amps power draw tomorrow. I don't want to shut it off right now. It's playing another demo piece with lots of pop and complex vocals. I'm going to have to run it with my Shahanian Obelisks someday soon. (The Trident 1's are better.)

Photos show the amp, the power supply, and them running together. The Power supply is keeping the amp from being pulled off the shelf by the speaker cables.

Second Day of Listening to the Eval 1 by Purifi Audio of Denmark

Lori Leibermn - "The Girl And The Cat" - Remarkable clarity. Great piano sound.
The Kenny Rankin Album - Lush!
anything and everything else - Oh my, that’s interesting! Wow!

You’ve heard of Hypex and the nCore amp modules, used in many commercial amps, NAD among them. Bruno Putzeys designed them and joined up with Lars Risbo, then, the ace designers & developers of Class D amps joined with Kim Madsen and Claus Neesgaard to form Purifi Audio and decided they would solve the most vexing problems in audio. They are doing very well at it!

The 1ET400A Class D module, an output “power amp” with a gain of only 13 dB (remind you of anybody else’s low gain/outstanding performance amps?), an output of 400 watts at 4 ohms (that’s different!), 25 amps of output current available, neglible distortion and noise of any kind, and an output impedance too low to measure (it’s in micro Ohms!). It will not have trouble driving ANY speaker and will not interact in ways that cause its output frequency response or distortion products to vary in any noticable way. Odd crossovers and speaker impedance shifts with frequency will not phase it. (No pun intended.) Not bad! And they are working on “high voltage” modules that will produce 1 and 2 Kilowatts (!) of power at up to 40 amps of output current. And they have a very interesting 6.5 inch mid/woofer with outstanding performance if you have an extra $350 in the bank.

One consequence of the behavior (or lack of it) of this amp is that if a speaker is capable of sounding good, it will. But, if something is not right, it will be obvious! I tried three different speakers of good reputation and was stunned to hear them sounding very similar. I tried a DIY speaker I was very proud of and discovered that something was terribly wrong with the crossover. The Milk Carton Kids sounded like they were stuck in the milk carton itself. I thought I had obtained 85% of the performance of the Raidho D1; not with that crossover, fella! Why did that flaw not show up with ever other amp I have on hand? I wish I knew. An hour of woofer crossover coil changes solved the problem, but wow, the good stuff tells the truth whether you wanted it to or not.

I haven’t found any data on the “damping factor” of the amp. It must be enormous. You’ve heard about “tight bass” being a selling point for solid state amps. The amp doesn’t just push a speaker’s vibrating element forward, it also pulls it back. High amounts of feedback allows the amp to tightly control the speaker, but it lowers the amp’s gain. A well designed amp can tell the difference between the speaker’s actual motion and what the amp told it to do. Such an amp can produce an “error correcting” signal to encourage the speaker to behave properly in real time. (Some amp designers feel the speaker’s behavior is not his problem. That sort of thing is the speaker designer’s problem, not his. Those amp are the ones that “sound best with speakers from X, Y, and Z Labs.”) At only 13 dB of gain, you can see the amp is using a lot of feedback, but it pays big dividends in speaker control. And it can put out 25 amps of current! (Assuming the power supply is capable of supplying it.)

The efficiency is remarkable. Playing it loudly, the amp pulls less than 18 watts from the power line. Its idling power drain is just over 16 watts. Playing the big number from Handel's Messiah, it pulls less than 20 watts (using Triton One speaker from Golden Ear. Even using four inch coaxial, 85 dB sensitive speakers, I couldn’t get the amp to draw 20 watts at a level I feared would damage the speakers.). I have meters on the three power supplies; they never move. So here is a big clue; the power supply is not strained and/or its fluctuations are so brief so as not to make the needle move and/or having 120,000 microfarads of capacitors on the high voltage power supply helps a lot! The 4 amp fast blow fuse has not blown yet. Also, it’s likely that this amp will not need fancy power cables. But opinions differ.

With no input, the amp is dead silent. That’s where “blacker blacks” come from. If the EVAL1 package is still available from Purifi Audio when you read this, realize you can build a power supply and have this amp running in your system for about $1000. If you you want a fancy cabinet, that’s extra. I don’t care how it looks, I only care how it sounds. If you have free roaming pets or small kids, a cabinet is mandatory. I started writing this on a Wednesday morning and it’s now late Friday afternoon. On Sunday, I’ll compare it to my wonderful Elekit TU8600R tube amp and see what happens to its sweet delicacy.

Sunday came and dusk approaches. The testing is concluded. Well, it’s over; the results are in and the results are clear. First Prize goes to the Purifi Audio EVAL1 package. It’s clearer, cleaner, more defined, more transparent than anything I have in the house, certainly; and the best I have listened to. It presents music in a more “natural” way; which seems an odd thing to say about a Class D amplifier. But we pay to view movies at 24 frames per second; we happily watch TV at 30 frames per second; so why should seem odd to hear music sampled at half a million times per second. CDs give us music sampled at less than a tenth of that. And it only costs us less than a forth of the electrical power that a 300B tube using. 9 wpc, Class A stereo amp pulls from the wall. My charming, beloved, ever so sweet, non-fatiguing nine watter pulls 88.9 watts; the Danish Wonder pulls not even twenty under normal conditions. The wattmeter may not be able to indicate the very rapid fluctuations in the amps power consumption.

The difference is most obvious when listening to the background or harmony vocals sung by the same performer who sings the melody lines in a studio production. You know it’s the same performer in the same booth, on a different “take,” but with the volume cut down 10 db or so. But there they stand, in three dimensions, breathing like a real person, not a paper cutout - a twin. You can’t tell what their hair color is, or what perfume the ladies are wearing, but just about everything else.

Tiny metallic transients are more than clicks that seem somehow to have a pitch. No, they are chimes of very short duration. There is music there, not just percussion. Also, the tape hiss, which I never noticed before, is clearly audible on certain older recordings. No doubt, that’s because the Purifi Audio amp is virtually noise and distortion free.

This module, the 1ET400A, is currently used in some production amps selling for $5000 (NAD M33) and up, WAY UP. But, if you hurry, you just may be able to get a pair of them, along with a suitable - gain increasing - protecting - totally compatible front end with connecting (balanced input, banana output) sockets for around a fifth of that, including your DIY power supply. You’ll find them at www.Purifi-audio.com.

The right channel of the Eval 1 protection circuits kicked in about 5 PM. August 12, 2020. I don’t know why. The right channel’s “OK” light did not light and the output was silent. I turned it on and off a few times waiting a minute or so between tries. Nope! I wore black PJs to bed that night.

I was going to order a pair of Maggie LRS speakers to run with it. Alas!

Just for “old times sake” I turned on the EVAL 1 the next morning; it worked! Happy day! God answers the prayers of His audio enthusiast followers. Halleluah! Then it occurred to me that I had put 120,000 mfd. of filter capacitors on the high voltage (+/- 63v) power supply, 60,000 mfd on the op amp power supply ( +/- 20v) and 10,000 mfd. on the gate supply (15v) - so - the error detecting cicuits, once triggered, would not reset until the power supplies had died out completely. That takes a looooong time. The amp has an “enable operation” switch, not really a power switch. My power supply has a switch that disconnects it from the AC power line but does nothing to dissapate the energy stored in the filter capacitors. My power supply has LEDs and meters on the three sections, but it still takes a while (I just went to time it - I got tired of waiting at ten minutes) for the voltages to drop low enough for the circuitry to reset. The high voltage light is still on with 30 volts or so and the lights are finally off on the lower voltage supplies, 2 volts or less. Purifi Audio suggests leaving the amp powered up all the time since the power drain at idle is only a watt or so. I’m a belt and suspender kind of guy, so I turn the power supply off. I’m in Southern California. We get power surges that make the bathroom nightlight scorch the paint on the wall. No Kidding!

Well, from my point of view, since you can build the power supply for $150 or so and get the EVAL 1 for about $850, you can have the best stereo power amp available for $1000. I’m ordering another one. And a set of Magnepan LRS to go with it. Ain’t life grand? Keep smiling!

The Stereophile Magazine, September 2020, contains a rave review of the $10,000 LKV Veros PWR+ power amp. It uses the Purifi Audio 1ET400A modules. It impressed reviewer Herb Reichert as being “a remarkable balance between analytical and romantic . . . sounded more Class A than Class D . . . played equally rich atmosphere - soaked through the entire audio band. It did atmospheric dreamy like Class A does atmospheric dreamy. Surprising and impressive.” Curiously, the same issue praises my favorite tube amp, the Elekit TU8600R as ” . . . ambiance sensing . . . expos(ing) the unique forms and harmonic spectra of the individual notes.” But the Purifi modules do it even better. Compared with another, well regarded, Class D amp - the Bel Canto REF600M; ”the LKV rendered berimbau (a Brazillian instrument) with a more complex palette of overtones and showed infinite variation in string attack. . . . soundstage depth was dramatically deep. What the LKV was doing seemed inexplicable. . . . (its) sound like limitless, sensual, tactile, luxury Class A watts.” Italics are the author’s, the parenthsis & capitalizations, mine. The final words in the review T400A modules remove the clear greeting card plastic wrapper our recorded music comes in. You know, the one that says, “This music was recorded for your enjoyment at this time.” You just hear the music as it was being played at the time.

Please allow me to repeat and earlier paragraph for all the DIY folks out there. Well, from my point of view, since you can build the power supply for $150 or so and get the EVAL 1 for about $850, you can have the best stereo power amp available for $1000. I’m ordering another one. And a set of Magnepan LRS to go with it. Ain’t life grand? Keep smiling!

Friends, we can get a discount (about 5%) if we can put together an order for four EVAL 1 packages from Purifi Audio in Denmark. It will arrive in way less than a week; they ship by Air DHL (mine came 3 days after placing the order). Contact me at [email protected] and join (it’s free) the DIY oriented Ventura County Audio Society - today!

P.S. I’ll set up tables in back yard and we can have a power supply building party!

So is this review to be taken as one from an objectivist or a subjectivist or a hybrid SOBjectivist?

 

[Colonel7]

Back to the OP. I pulled the trigger on the new Purifi Mini from @Apollon Audio. I don't need the tremendous power of my AS1200, which I could put on sale soon.

Pearl white or black? Love the look and can't get better inside

 

[eddantes]

https://internetofmusic.nl/product/iom-classic/