I've got the Audiophonics HPA-S400ET Amplifier and swapped the LM4562 for both OPA1612 and OPA1656 (which can both be purchased at audiophonics too), with both sounding more detailed than the stock opamps. The nice thing about the audiophonics amp compared to the stock purifi is that you can easily swap the opamps without soldering as they are just socket mounted, letting you swap back and forth. I prefer the OPA1612 as it gives me a wider and deeper soundstage with super detail and "pitch black background" noise levels to hear sound decay for ever and ever, while my GF prefers the OPA1656 as it puts the singer in clear centerstage while still being very detailed, though a more flat and forward soundscape.

@mykandrew

Жыл бұрын

This is the one thing I regret not doing while I had the amp, however it wasn't mine to tinker with and if something had gone wrong I would have been personally liable.

@Nikolajchris

Жыл бұрын

@@mykandrew I imagine the results would be what you got from the stock design with those opamps, so don't think you missed out as such :)

I love my new Buckeye three channel Purifi amp with the 1ET400A modules and custom input buffer. VTV also makes some good amps on these modules

I just bought and assembled the Hyper Nilai 500 Stereo kit. Everything went perfect, no mods needed. Just too bad Purifi / Ghentaudio don't have exactly the right kit. I'm sure the Purifi is as good as the Hypex. I even got the DIY ClassD Preamp, very nice too. My source is an Ayre QB-9 and speakers are the Ryan R610: Sounds marvelous with the Hypex Amp / Preamp combo! I used to have a Rega Elex-R but the Hypex is a nice upgrade: Impression that the amp drives the speakers perfectly, tight basse and refined mids and highs. I'm VERY satisfied!

Interesting job and good description. In comparing the two amps, the preamp used is important for the sound quality because of the impedance bridge between preamp and amp. One important difference between the Eval1 and the Audiophonics board is that Eval1 has only 10.2kΩ(BAL)/5.1kΩ(SE) input impedance compared to HPA-S400ET's 94kΩ(BAL)/47kΩ(SE). So you need at most 510Ω RCA output impedance from the source/preamp to get a minimum recommended 10:1 ratio. Many tube preamps (which go well with class D) have higher than that (like 2kΩ), so it might compromise the Eval1/Purifi performance. Audiophonics and other integrators play safe with their input buffer boards choosing higher input impedances than Eval1 (higher resistors at the input), which some users prefer for SQ. However higher resistors introduce noise aswell, so it's a tradeoff. If your preamp is strong enough, is well buffered and has low output impedance it will play better with Eval1. Regarding the OPA1656 it is curious Bruno recommends it when he chosed OPA1612 for their Eval1 (least measured distortion). More Purifi integrators choose OPA1656 aswell, like Boxem Audio in Europe.

Thouroughly enjoyed Mike. I have a big Pass Labs 250w AB monster. But you’ve motivated me to order these parts, have a big of fun and build an amp. Great job. Tx!

@mykandrew

Жыл бұрын

You will definitely enjoy it! Thanks for the support.

I use a Legacy Monobloc2 power amp. Fantastic sounding and powerful amp. It does not get hot ever even when I play pretty loud music with lots of bass for a longer period. Buy used but in excellent shape is the trick :) 😀 but for example here in Canada you must be patient for different brands or models, like my Legacy Monobloc2 which are very rare on the used market :) cheers and happy holidays

Nice review good to see Mike G he made a ac voltage buffer for my first DIY amp that used the ClassD companies boards, it was a great intro into the "D" side of amps

@mykandrew

Жыл бұрын

I feel like we are just at the beginning of a huge improvement in quality for Class D.

@jerrysnead2842

Жыл бұрын

I feel they have been good for a while, I've owned Dsonic, Acoustic Imagery, Nord M500's and now the PS Audio M1200's

6:45 did you do blind ABX testing. REW plots? With/without EQ? What about the Audiphonics (and project one) in bypass mode which bypasses the OpAmp. The Audiphonics one is socketed too so a simple swap, so what did you think of it with the other OpAmp?

Mike, this is an awesome video and project!

@mykandrew

Жыл бұрын

Thank you so much Shawn!

This actually a great project and presentation. If your links are correct, the cost of replacing the op amps is less than $10.00 (tax, shipping, etc... for 2) I wonder if you would have put in sockets when you replaced the op amp? Can't be much more money...And you'd have more options... right?

As much as I love my Parasound 2125v2 for my GoldenEar BRX, I've upgraded to NAD C298. My Parasound will be moved to powering the surround L/R speakers in a mixed use music/movies 7.4.4 setup. My requirements (

@mykandrew

Ай бұрын

I’ve been trying to get my hands on the NAD to test it out. Hopefully someday.

@mrpmj00

Ай бұрын

@@mykandrew reviewers have said that the NAD m23 sounds even slightly better than NAD c298, but I didn’t want to spend $1000-1400 more and lose the gain knob and more importantly lose the RCA loopout for my 2 subwoofers. i’ve just subscribed to your channel. my channel: kzread.info/dash/bejne/aqGss5R7ec3Zp9Y.htmlsi=QY1m6NeEVtR2vbN6

@mrpmj00

Ай бұрын

@@mykandrew My video of the NAD C298: kzread.info/dash/bejne/oJerpdGpnquwoaQ.html

What do you think about using the VTV input board and putting an opa1656 on it?

Thanks for the great video Mike! I've been looking forward to this one and appreciate very much the effort you put into making these video. Comparing this to the other ICEpower amp you built a while back (~$300), how much better does this sound? Is the ICEpower at least 80% of the sound of the Purifi? Thanks in advance!

@mykandrew

Жыл бұрын

Thank you for the kind words. The Icepower isn't in the same league as the Purifi unfortunately.

Recently got into hifi with a Cambridge CXA81 integrated amp and KEF q350 speakers, but I’m considering returning the speakers for LS50 Metas ..so I may also have to rethink my amp situation, since the 81 might not be powerful enough to bring out the full potential of ls50s .. This class D setup looks like a great option - I see a pre-assembled version for $1000 or so U.S.. but I’ve never dealt with separates before. For now all I need is a way to get TV and/or computer audio into it (LG C1) .. Will a Schiit Modi 3 be enough until I can afford a decent preamp? (TOSlink from TV into modi, RCA out from modi into amp)

Hi Mike, I think you replaced the opamp on the Eval1 board. Did you test that opamp on the Audiophonics board also? To find the differences?

@mykandrew

Жыл бұрын

Since the Audiophonics isn't mine to keep I didn't want to make any modifications that could affect the unit itself. However they use the removable OP amps which is a HUGE selling point for me.

Great video! Mike's system is an amazing reference. I'm very curious about how this Purifi module could be developed further.

@mykandrew

Жыл бұрын

I am going to stay in close touch with Purifi about any further developments. The amp is solid and flawless, I can't wait to see what they come up with next!

@hilde45

Жыл бұрын

@@mykandrew Did you see this? kzread.info/dash/bejne/gXWEk5dxhc6oZtI.html&ab_channel=PearlAcoustics

Can you please tell me where on the circuit board to put the solder after removing the switch? Thanks

Nice video. What type of audio analyzer do you use for the measurements?

what's the original OPamp on the board? whats the difference in the OPA1656IDR and the original that makes it sound better?

Hello Mike, great video, this open up a new world for me regarding DIY Amp build. Question, would this class D amp Purify Eval1, 2, 3 would be suitable for current hungry Magnepan 1.7i ? THANK YOU!.

@mykandrew

5 ай бұрын

This amplifier feeds my Infinity Kappa 8 speakers which were referred to as the “amp killers” back in the day. So I’d say yes it would be perfect!

Audiphonics stuff ROCKS really good value for these. Cheaper than self-build kits from others with more features too. The only thing I don't like is the mad bright blue lights on the buffer board.

The Op Amp link does not work. Does the stock EVAL1 input board allow you to roll opamps? Or do you have to use a different input board?

@mykandrew

Жыл бұрын

I fixed it, you have to unsolder the old one and solder on the new one. It's not plug and play unfortunately.

Very different, but I feel you get a better DIY experience with some of the PASS stuff. More soldering and more learning, yet you are almost guaranteed to succeed if you are diligent. As far as 25W vs 2-3,000 or million - whatever class D can offer, that is a dangerous argument. All depends on the speakers you want to use. I am very happy going down the tube and class A route. I like the soldering but really have problems with the very small SMD parts on class D projects. There is A LOT out there to try. You will be going down a rabbit hole that you'll likely enjoy very much.

Awesome stuff!! Just wondering if you could add an 8 pin socket to the board rather than soldering in the new op amp?? This would allow the flexibility of swapping op amps in and out. I would love to see a quick video of you replacing the op amps. Thanks!!

@mykandrew

Жыл бұрын

We thought about that, perhaps on the next one.

@JeradBenge

Жыл бұрын

It would make me happy if the amazing OPA 1656 was available in 8 pin, but that's a different conversation. An 8 pin socket would be great for using the variety of discrete opamps available. I smile when I crack open a case and find sockets.

@mykandrew

Жыл бұрын

@@JeradBenge I'm hoping for that as well in future models of this build.

Great video! Does you long-term impression confirm your initial enthusiasm?

@mykandrew

7 ай бұрын

Absolutely, I'm using it in my bookshelf system, and it provides amazing power without any distortion. Clean.

Hello Mike, Thank you for this informative video. I just wanted to confirm that you swapped out the Op Amp in the input stage? Also,I was wondering if you have done any listening to GENFET Class D amplifier…. I understand that they Class D to the v by ext level….more quicker, concise and even less muddy.

@mykandrew

Жыл бұрын

Two OP amps in the input stage yes. Haven't tried the amp you mentioned. I am getting quite hooked on class D.

Man I would love to have VU meters on this build. If one were to build this, how can VU meters be added?

WoW! Great video! What pre amplifier do you suggest to go with it? One with a good Dac and similar price? Thank you.

@mykandrew

Жыл бұрын

Thanks for the support. I actually use a vintage Adcom preamp, I suppose most well-regarded preamps will work well. Any you had in mind?

@Adbyte-vu4io

Жыл бұрын

@@mykandrew was thinking about the NAD C658 with the Dirac software, my speakers are the Buchardt S400 MKII

I want! You almost had me thinking I might be able to build my first amp, but unfortunately I'm looking for a 3 channel Purifi. I don't suppose that option is available? Didn't see it from the links you provided.

@mykandrew

Жыл бұрын

Why 3 channels?

@ryanw8664

Жыл бұрын

@@mykandrew Front stage of home theater system (left, right and center channels)

Hey, thanks for the video! Did you notice any turn of pop/ thump in the tweeters with either Purifi based amps?

@mykandrew

Жыл бұрын

Nope both clean.

@avgeek8810

Жыл бұрын

@@mykandrew Great thanks! I guess no turn on pop either 😃

@mykandrew

Жыл бұрын

@@avgeek8810 nope, the PSU clicks on as it should thats it

@avgeek8810

Жыл бұрын

@@mykandrew Great thanks!

Does this come with all necessary cables too? What was your total cost? Thanks!

@mykandrew

Жыл бұрын

It came with all the cables needed. Total cost is around $1k

Hey Mike, How does this DIY amp sound when compared to your $300.00 DIY amp made with ICE modules ? Is this new amp $ 700.00 better? If so, in what ways ? Thanks, McJerry

@mykandrew

Жыл бұрын

This amp both measures and sounds better than the Icepowrr by a considerable amount. I think all in the Icepower cost right around $300 and this one was around $1000 and yes very much so worth the difference.

@jerrymcnutt339

Жыл бұрын

@@mykandrew , thanks. McJerry

How many watts/channel as per standard 20-20khz measurement?

What was the total cost? How many watts per channel?

How much did this amp cost? Would it be available for regular people?

@mykandrew

Жыл бұрын

Total all in Under $1k

Hi can we buy this from you and use in uk London as finish as this you showing here 🎉

Hey guys I got a build question…. Option 1: Two Hypex Ncore NC400 mono blocks and using my pioneer head unit for my DAC and pre-amp..? Option 2: Two Crown amps model 1502 bridged to mono blocks and also purchase the Topping D90SE flagship DAC / Pre-amp. I would sell off my pioneer head unit Both options work out to be about the same price. The Topping D90se is a fantastic DAC for $899. Let me know and thanks 👍🏻.

Please could you tell me what would be a good dac to use.

@mykandrew

Жыл бұрын

Could you describe your system so far and what budget you are working with?

Maybe call it the Purity 1 or Moa 1. Of course there will be variations based on the actual op-amps being used, and one can expect the offerings from Purifi and Hypex and Ghent to change over time. But your actual project amp, as is, would be the Purity 1. I intend to place orders to DIY one myself, but it’ll be with the standard case, in which case I’d describe it as a Purity 1, but with a standard case and stock op-amp.

@mykandrew

Жыл бұрын

How about Purity MK 1 😀

I know that this is an old video, but can I get purfi amp boards sent to the US? I have been looking online and can't find any info

@mykandrew

Күн бұрын

Check the Purifi website, I should’ve put links in the description. I’ll double check.

@BostonMike68

Күн бұрын

@@mykandrew thanks I went on there website and they had the European and Dutch or something payment, I wasn't sure if we could get them in the US

Dear Mike, I was looking to buy a Class D amplifier and step by your excellent video. Thank you. Can you help me with some questions?: -Will this amplifier will sound better than the Nord with 1ET7040SA? - I need a banana for my speakers and I couldn't see that the box included bananas, where did you buy them? - Is it difficult to change the Oamps? I saw 8 legs but on the the eval 1 picture it seems like 3 legs or there are the one in each side? - Lastly, do you sell the already made amplifier? Thank you VERY much!

@mykandrew

Жыл бұрын

Thank you for your support and kind words. I will try to answer the questions to the best of my ability. 1. I have never tested the Nord however the EVAL1 is the BEST sounding Class D amplifier I have heard in its price class. 2. Ghent audio sells the banana kit, however I bought my fancy plugs directly from Audiophonics. They have a nice selection. 3. Currently the OP amps are surface mount so you have to unsolder the old ones and solder on the new ones. 4. I do not sell these unfortunately.

@ilandvash6746

Жыл бұрын

@@mykandrew Thank you very much. Happy new year!

@ilandvash6746

Жыл бұрын

@@mykandrew Last question, is the eval1 better than the nc1200 from your point of view?

@mykandrew

Жыл бұрын

@@ilandvash6746 I would go with either one. I find the NC1200 a bit bassier which I like, but the clarity and dynamics of the EVAL1 is 🔥

@ilandvash6746

Жыл бұрын

@@mykandrew Thank you very much! I think I will buy the products and start to build my amplifier.

Man if the boards could be ordered with the op amps socket mounted, and the power switch removed and resoldered to constant on, I'd buy this. My hands are no longer steady enough to solder surface mount. I just thought about this with a tube pre-amp powering a pair of JBL Studio 590 or Maggie LRS

@mykandrew

Жыл бұрын

I will keep you posted of new developments, don't lose hope.

@ericperry72

Жыл бұрын

@@mykandrew please do, I think you are onto something. If the performance right now is killer, imagine those few changes and upgrades! Hell you got me looking for a high quality but budget tube pre-amp to run with this amp design so I'm vested in any new options.

What was the total cost? Did you have to build 2 for stereo?

@mykandrew

Жыл бұрын

This is a two channel amp so only need to build one. It came out to around $1k.

what module is the Op Amp swapped on?

The OP amp link goes nowhere I’m afraid. Great video!

@mykandrew

Жыл бұрын

Should be working now.

Nice video, and certainly nice build. But I was expecting something a bit more new or special after reading the title. You basically made the simplest purifi build with the basic eval1 board, which is very old stuff. This would be something different when you build a new input buffer boards, which sounds much better. You could also build the neurochrome input board or maybe build a tube based board or something new ;) Still, nice video for everyone who didn't know about modern class d.

@mykandrew

Жыл бұрын

I think swapping the surface mount op amps changed things quite a bit, however I feel like doing a new input board could be a lot of fun for a future video.

@kaptn_kapton

Жыл бұрын

@@mykandrew that is the spirit :)

What's the Project amp that's mentioned?

@mykandrew

Жыл бұрын

That IS the project amp

Why an internal switching power supply over a quality linear power supply?

Please do a DIY super Tweeter setup!

@mykandrew

Жыл бұрын

@aperionaudio offers an excellent pair of super tweeters, I don't know if I can top that. I could try!

Maybe I missed it but what was the total cost?

@mykandrew

Жыл бұрын

I fotgot to add it lol it was a little under $1k for all the parts

pureifi modules link is dead. Is this permanently unavailable?

Can we buy this from you guys

Do you have a diy for a 3 channel

@mykandrew

Жыл бұрын

I'll have to find one. That sounds fun!

There’s something I don’t quite understand.If two amps measures very similarly how do you explain they sound so different ? A good amp does not color the input signal, it just amplifies it. That means that if you look at an audio sample as a sum of sine waves of different frequencies and amplitudes it will add fixed gain factor to any one of them. In the measurements that would look like the amp has a flat frequency response, which both the Purifi reference design and the Audiophonics amp have (you also measured the same on your “custom” amp). If that is the case and y here’s also no difference in the distortion level at similar output level in both amps, I really find it hard to believe they would sound different. My bet is on one of the two: 1. Our minds is doing tricks on us. When you know which amp you’re listening to, your test is biased. Switching back Ann forth between two amps without knowing which is which is a different thing 2. The gain of the two amps is a bit different (at the same setting on your preamp one is louder than the other) and you didn’t do level matching before the test I bet that if you perform a level matching,, connect both amp through A/B selector and do bling hearing test with someone switching back and forth between the two amps, on the same track, you wouldn’t know which one is playing. That statemeny is true for Audiophonics vs your amp and for the OPA swap (assuming flat frequency response and SINAD difference bellow sonic impact on all configurations) Bottom line - if you cannot measure a difference there is no difference

@mykandrew

Жыл бұрын

From an objective viewpoint, you are correct. They were level matched, but it was a sighted test. There could be bias. However, two of us both heard a perceived difference. My question to you is, why would the amp designer suggest an OP amp swap to improve the sound? Objectivity is great, but to truly test a system, you have to have a subjective listening session. I will work on setting up blind tests in the future. Thank you for the feedback I understand where you're coming from.

@frankderks1150

5 ай бұрын

Gain is set by the resistors and a simple swap doesn't cause any difference in gain in the audio range. The 1656 is a FET input, can drive 100mA has very low input bias current and has a much, much lower current noise figure. I think the 1656 is a better driver for the purify module. Especially when there is a fairly large voltage swing needed if the high gain setting is used. SINAD is useless performance number since there is trickery involved measuring these low noise floors in opamps that have on order of magnitude lower noise than even the best audio analyzers.

Thanks Mike, this is soooo excellent a video. Let me recap what you presented, just so that I fully understand what was said. The audiophonics complete amplifier comes with its own input board attached to the Purifi amp boards. Your project version has Purifi’s own input board attached to their amp boards (forming what is the Eval1). Ordering the Eval1 from Purifi; the Hypex power supply from audiophonics; and the Std case (I assume it includes built-in banana connectors for the speakers) from Ghent, per your links, will get me an easy-to-build, no-tools-needed-other-than-a-screwdriver kit that anybody can put together? Pinch me if true!

@mykandrew

Жыл бұрын

That is exactly correct.

@foblivio

Жыл бұрын

@@mykandrew Hi Mike. Was an IEC power cord included?

@mykandrew

Жыл бұрын

@@foblivio Nope, I had to provide my own.

🌸❤️❤️🥀

@mykandrew

Жыл бұрын

Thank you!

I've still yet to get a an explanation as to why US folks don;t pronounce the L in solder ... it seems like the national pastime is dropping letters from words. 😆

@mykandrew

Жыл бұрын

Lol

@howard5992

Жыл бұрын

The ' L " sound was lost centuries ago... Etymology - Middle English soudure, from Anglo-French, from souder to solder, from Latin solidare to make solid, from solidus solid.

@zincyellowmach1523

Жыл бұрын

Because it sounds like you're choking on your tongue when you do lol

@Jack96993

Жыл бұрын

Dang it! We consider it a silent L 😂

@codydowling1120

11 ай бұрын

Hehehe 😂 I don’t think that is the issue- the issue is most of us don’t pronounce the long “o”. Therefore, it’s “sawlder”. 🤠

I love my IcePower 1200AS1... all in one, I need nothing more.

@mykandrew

Жыл бұрын

Until you hear the Purifi amp.

@MS-ug3gm

Жыл бұрын

@@mykandrew is there really such a big difference?

@mykandrew

Жыл бұрын

@M S I built an Icepower amp, there's a video about it on here. Yes, huge difference when you need to power hungry speakers like my Infinity Kappa 8's.

@MS-ug3gm

Жыл бұрын

@@mykandrew what about sound quality, stage, micro details? Are they better?

5:04 it's a great situation for anyone who has 230V available. 😜

How many best amps .............???? in the world !

You make a DIY video and forgot to mention the cost a bit clearly?

@mykandrew

Жыл бұрын

Under 1k

Class D is the future.

4.8k for a diy kit 😅 i can buy a beautiful cambridge edge or rotel michi that’s a plug and play amp over this at the same same price level.

Took you long enough, haha.

@mykandrew

Жыл бұрын

OP AMPS Matter you were right lol

@ranbymonkeys2384

Жыл бұрын

@@mykandrew Mike, there are still engineers and audio people that say they all sound the same!!! Absolute insanity!!!

So don't do this ? Because it doesn't sound good?

@mykandrew

Жыл бұрын

It sounds fantastic

DUDE LISTEN TO YOU GASP FOR AIR BETWEEN WORDS. MY GOD Dude LOOSE WEIGHT OR TURN THE MIC DOWN AND BACK IT AWAY FROM YOUR THROAT

When you use premade kits, I wouldn't call it "building an amplifier"

@mykandrew

7 ай бұрын

When you aren’t an engineer and doing more than plugging in the mf then yes it’s building an amplifier!

This is not a DIY kit.all you do is plug stuff together. All cables cut to size all boards are full assembled. I would expect to assemble the boards from individual components, a circuit diagram and how to set and check voltages etc.

@mykandrew

Жыл бұрын

This isn't meant for advanced DIY. For you over achievers, you should make videos and show us beginners how it's done 😉

@charlesdpetrone941

Жыл бұрын

I agree that is too easy. You should wind your own transformers and design your own transistors and integrated circuits. Growing your own silicon crystals shouldn't be too difficult, they are just made of sand.

@mykandrew

Жыл бұрын

@@charlesdpetrone941 lol exactly. I didn't know I needed a degree from a University to do DIY audio as a hobby.

I recently purchased a Purifi EVAL 1 stereo amp and it’s great but I actually prefer my Hypex NC500 mp mono blocks a bit more . I prefer to use a tube preamp or SS preamp and rely on the preamp to do the coloring. I don’t want a amplifier that has a distinct sound. Not a fan of alternative Op amps .

@wyup

6 ай бұрын

which preamp do you use for that?

@miquifaye

6 ай бұрын

@@wyup Schitt Freya plus in tube mode.

@wyup

6 ай бұрын

You can bypass Eval1 input buffer and opamps aswell with your Purifi for single ended, Freya balanced output impedance at 600Ω is too high for Purifi 4.4k unbuffered. NC500MP has an input buffer built-in of 13.5 dB and 47kΩ. You can't bypass its opamps unless you remove two resistors (I know because I did that with NC122MP), so you must get a lot of gain with Freya, even single-ended, and require high attenuation, isn't it? (12db+13.5db+12db=37db combined)

@miquifaye

6 ай бұрын

@@wyup The Purifi sounds great with the Freya + . I had no impedance issues in my setup . They actually sound quite similar. Most people couldn’t even tell in a blind test . I just prefer the bass quality of the NC 500 monoblocks . The sound Is a tiny bit deeper and fuller and the separation is more distinct. It could be that they’re monos vs a stereo amp . I could live with either of them easily. I’ve had 2 sets of Hypex NC 500 monos and there’s just something magical about them to me . When I sold them , it was a sound I actually missed. I guess I like the neutrality of it.

@wyup

6 ай бұрын

@@miquifaye Let me ask you: with 500W and a gain of 37db, don't you use too much attenuation for normal levels? e.g: volume pot ramping up fast in volume from lowest positions?

If only I was brave enough to build this😬🤔🫣😂