Are Class D Amplifiers really "digital"?

[57gold]

Cool.  Your build layout looks great.

 

Kind of ironic that you chose a case that has so much heat sinking when these are supposed to run very cool. Guess its dimensions help with optimal layout.

[barrows]

52 minutes ago, 57gold said:

Cool.  Your build layout looks great.

 

Kind of ironic that you chose a case that has so much heat sinking when these are supposed to run very cool. Guess its dimensions help with optimal layout.

Finding or building a decent chassis is one of the huge problems with DIY, unless one has some skills and access to a good machine shop it is slim pickens for nice chassis out there.  I chose this one because I could get it, the dimensions were about right, and it was made in the USA with high quality workmanship and materials.  The fact that it has heatsinks is not applicable to this build, as the Purifi modules are very efficient, and Hypex has improved the efficiency of the SMPS 1200 as well.  Even in this case. sealed with no ventilation holes, the amp runs barely warm in a 70 degree room when blasting for an hour at 88 dB average levels.  BTW, I have an NC-400 DIY in the same case, except with ventilation holes, and the Purifi runs much cooler than the NC-400.  I do not think there needs to be much consideration of heat sinking with an Eigentakt stereo build with a Hypex SMPS 1200 as long as the modules are tightly screwed to an aluminum plate.

[Matias]

On 10/4/2020 at 12:02 PM, barrows said:

As I build my own amps, I have not really spent a lot of time paying attention to the amps that are available with Purifi modules.  A lot of the offerings, from say, Nord et al, appear to have less than ideal internal layouts for some weird reason.  I do like the options which allow for the pro audio style discrete opamps, the pro audio discrete opamps from Weiss, for example, are very, very good.  How much does all this matter, I do not know, but I prefer an amp with a logical and well sorted internal layout.

To me Apollon build quality is second to none. That is why my 2 amps are from them.

 

For example their mono Purifi amps with pro opamps below.

https://www.apollonaudio.com/purifi-1et400a-apollon-audio-monoblock/

 

 

 

[YashN]

1 hour ago, barrows said:

Finding or building a decent chassis is one of the huge problems with DIY, unless one has some skills and access to a good machine shop it is slim pickens for nice chassis out there.

 

What's up, barrows?

 

I have a fair number of them from visiting thrift shops. In other words, I look for cheap as chips gear with a chassis and re-use those.

 

The metal you see in my avatar here comes from one of those.

 

I get them for around CAD5 - 10, so less than $10...

 

Sometimes, if I'm lucky, I also get quite a good transformer for Linear PSU builds as a bonus (with other re-usable internal parts).

 

I sometimes also get gear for free: given away or thrown away. Cost to me is zero.

 

Some of the chassis require a paint job, some require drilling, additional metal work, but beats having to buy and ship a new chassis for me so far.

[Matias]

Ghent and Modushop both sell various sizes of chassis too.

[Qhwoeprktiyns]

The Audiophonics model, which I recieved today ( https://www.audiophonics.fr/fr/amplificateur-de-puissance/audiophonics-hpa-s400et-amplificateur-stereo-class-d-purifi-2x400w-4-ohm-p-14393.html?search_query=purifi&fast_search=fs)  has these modules:  TI LM4562. The Purifi Eval Board has OPA1612. I believe the Nord has those as well. They can be swapped on the Audiophonics model. Any reason to prefer one over the other ?

[DuckToller]

10 hours ago, hopkins said:

The Audiophonics model, which I recieved today ( https://www.audiophonics.fr/fr/amplificateur-de-puissance/audiophonics-hpa-s400et-amplificateur-stereo-class-d-purifi-2x400w-4-ohm-p-14393.html?search_query=purifi&fast_search=fs)  has these modules:  TI LM4562. The Purifi Eval Board has OPA1612. I believe the Nord has those as well. They can be swapped on the Audiophonics model. Any reason to prefer one over the other ?

Salut @Hopkins,

Nice to read that you've already received your Purifi amp.
I am very curious how you like it in comparison to your Lavardin integrated amplifier.
For some more specifics about op amps for the Purifi you may like to check out this review: https://bit.ly/3nxn3lQ
Cheers from the Loire valley
Tom

[Qhwoeprktiyns]

Thanks for the link. 

 

I had a late start last night, and listened to the Purifi amp in my system from midnight to 3AM:

ECDesigns UPL > ECDesigns Fractal DAC > The Truth preamp > Purifi amp > Davis Courbet 4 speakers

 

I initially had the "no gain" setting which bypasses altogether the opamps, and the sound was terrible - no bass, very thin sounding... I quickly changed the setting to its default, which provides more gain, and changes the impedance in some way (I don't have the technical background to understand all this). The sound immediately improved. Over a few hours, I think it continued improving, so there may be a warm-up aspect to all this.

 

The Purifi amps are very special. I did not have a chance to compare them directly with my two other amplifiers (Lavardin ISX and ECD MBL - the latter are no longer manufactured), but I did listen to a number of tracks that I know very well. What is immediately striking is the pitch-black background and very precise and refined sound of the instruments. The Lavardin amplifier seems to add a little "graininess", that could be perceived either as "distortion", or as "texture" - and that is where I honestly need to spend more time with them to form a definitive opinion.  I am comparing here "from memory" - the Lavardin is also an integrated amplifier with its own volume control.

 

The ECD MBL power amplifiers are in between those two (Purifi and Lavardin), and are quite remarkable in my opinion - having this "dilemna" (first-world problem) between the ECD amps and the Lavardin is what prompted me to try out the Purifi amps. I obviously need to spend more time than just 3 hours to confirm all this. I also plan to listen to all this with my (modest) vinyl source, and other preamps (ECD's SVC).

 

I had Hypex Ncore DIY amplifiers a couple years ago, which I was using with different sources, and Harbeth P3ESR speakers (I ditched the Harbeth - and never looked back), so it is difficult to compare, but my feeling is that the Purifi amps are in a different league. The "numbers" may not say so, but who cares about the numbers ? :)

 

 

[DuckToller]

@hopkins

I had the pleasure of listen to the eval kit (with the Purifi transducers) and a Mola Mola pre/dac, sitting between Lars and Bruno (the designers). I was certainly impressed, from both of them and from the precise clarity of the Eigentakt. However I felt somehow impacted by sheer presence ;-) Nonetheless, I am considering the Apollon Purifi Mini as an upgrade path ...
Cheers, Tom
 

[DuckToller]

8 minutes ago, DuckToller said:

Nonetheless, I am considering the Apollon Purifi Mini as an upgrade path ...*

* for the PS Audio S300 in my listening room

[Qhwoeprktiyns]

When it comes to Class D amps, I also had a chance to listen to SPEC amps, in comparison to an Audioflight amp, at a dealer's, using Harbeth Super HL5+. The Spec amp (I forget the model) gets a lot of praise in some circles, but I was not particularly struck by any differences in comparison with that other "non class D" amp. Thinking over this episode now, I would tend to think the Purifi amps are probably in a different league, but that is also certainly a little speculative. I'll be curious to read about more customer feedback about the Purifi amps, other than incomprehensible 6moon type reviews, now that they are more widely available. 

[Matias]

28 minutes ago, hopkins said:

I would tend to think the Purifi amps are probably in a different league, but that is also certainly a little speculative. I'll be curious to read about more customer feedback about the Purifi amps, other than incomprehensible 6moon type reviews, now that they are more widely available. 

There are several reviews out there. Short version is: clean and clear, powerful, uncolored and gets out of the way. Users on forums tend to agree with this.

 

Edit: one review in particular, from Audioxpress, is more forward thinking and his conclusion is intriguing. Where do we go from here?

 

https://audioxpress.com/article/fresh-from-the-bench-a-tale-of-two-class-d-amplifiers-orchard-audio-bosc-and-purifi-audio-eigentakt-eval1

[Qhwoeprktiyns]

27 minutes ago, Matias said:

There are several reviews out there. Short version is: clean and clear, powerful, uncolored and gets out of the way. Users on forums tend to agree with this.

 

Edit: one review in particular, from Audioxpress, is more forward thinking and his conclusion is intriguing. Where do we go from here?

 

https://audioxpress.com/article/fresh-from-the-bench-a-tale-of-two-class-d-amplifiers-orchard-audio-bosc-and-purifi-audio-eigentakt-eval1

 

I don't want to sound snobbish, but a listening test of two amps that are supposed to be "very low noise" with either a Behringer or a minidsp crossover in the chain, as described in that review, may very well defeat the purpose? 

[Matias]

1 hour ago, hopkins said:

 

I don't want to sound snobbish, but a listening test of two amps that are supposed to be "very low noise" with either a Behringer or a minidsp crossover in the chain, as described in that review, may very well defeat the purpose? 

Fair enough, disconsider the subjective parts of that review then. Others below:

https://www.soundstagehifi.com/index.php/opinion/1420-purifi-audios-pint-sized-powerhouses

 

 

 

[Qhwoeprktiyns]

Thanks. Those are all good reviews.

I'll carry on with my tests and look forward to hearing more about these special amps.

[57gold]

On 10/9/2020 at 8:52 AM, hopkins said:

 other than incomprehensible 6moon type reviews

 

Wow, I though I was the only one who held the opinion that 6moons reviews made absolutely no sense.  

 

Random babble for many paragraphs and sometimes, though rarely, a few words about how the gear being reviewed sounds in comparison to other similarly priced gear.  And even then, usually overwhelmed by one or more tangents about some tweak or cable or obscure recording...have given up reading their reviews out of frustration; when I get to the end of a review, I wonder why I bothered.

 

Believe the first review I read was one on the McCormack DNA-500, which was actually very informative and accurate.  I still have my DNA-500 and it rocks. It was written by Chip Stern, an outlier, who has a history of audio reviews and seems to understand how to describe the musical character of audio gear.

 

 

[firedog]

10 hours ago, 57gold said:

 

Wow, I though I was the only one who held the opinion that 6moons reviews made absolutely no sense.  

 

Random babble for many paragraphs and sometimes, though rarely, a few words about how the gear being reviewed sounds in comparison to other similarly priced gear.  And even then, usually overwhelmed by one or more tangents about some tweak or cable or obscure recording...have given up reading their reviews out of frustration; when I get to the end of a review, I wonder why I bothered.

 

Believe the first review I read was one on the McCormack DNA-500, which was actually very informative and accurate.  I still have my DNA-500 and it rocks. It was written by Chip Stern, an outlier, who has a history of audio reviews and seems to understand how to describe the musical character of audio gear.

 

 

 I find it funny/ironic that they call themselves the site for audiophiles who "like to read".... Apparently they have a minimum length for reviews, and in addition to length, the text must be obtuse.

 

That said, I think they do provide some useful info: they review products from small producers from all over the world that many other sites don't or won't. They also compare the sounds of products, so if you get to know the reviewers and have some idea of what the products sound like you can figure out which ones go on your audition list or don't go on your audition list.

[57gold]

Firedog, I like to read. Probably get through two books a week on my Kindle, daily local paper, NY Times, Bloomberg news subscription...

 

Chip Stern's 6moons review of the DNA-500 was not short; it discussed info about Mr McCormack, the design choices he made on his products and development and sale of his company to CJ and took care to describe the sonic quality of the amp versus others he had reviewed.   My honors English teacher would have given him an A for staying on point and supporting his conclusions.  This approach does not seem to be the framework for many a current 6moons review these days.  

 

Agree that 6moons seems to comb the planet for new products from small, up and coming manufacturers...as far as you can get from Best Buy inventory, which is valuable.  Guess they can be seen as the other side of the coin from audisciencereview.com where a review is a bunch of measurements, boiled down to one number.