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Questions For Interview With Bruno Putzeys & Lars Risbo About Purifi Audio

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OK, settled then.

 

13 hours ago, Shadders said:

Hi,

What you have said makes no sense. The specification states 65volts. It does not state it has to be an inductive - some people use linear power supplies which are primarily capacitive.

 

The only reason SQRT(2) is involved is if the power delivery are RMS values on the specification sheet, which would account for the 44volts voltage output, when multiplied by SQRT(2), the 62.2volts - very close to the power supply voltage - as expected.

 

Regards,

Shadders.

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16 hours ago, rego22 said:

As in addition to Bruno Putzeys also Lars Risbo is a co founder

That's correct and he is an active part in this Q & A with Purifi.
Thank you for your question about smartfi. 

Lars Risbo - although he is more commonly known for the development of the TACT - Millennium Digital Amplifier & his work for TI - has been in the seat for the newly developed driver PTT6.5W04-01A , that offers a "breakthrough" in the optimization of "the various distortion mechanisms" which "translates into low intermodulation (IMD): clean, undistorted midrange even in the presence of a heavy bass."

I can just invite you to use this opportunity to find out more on the subject of long-stroke-drivers and "negligible" distortion. 

Best, Tom

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3 hours ago, psjug said:

@The Computer Audiophile  when do you plan to do this?  I'm looking forward to reading what they have to say.

 

Hi psjug, please allow me to respond on the subject.
It is a matter of days to get the Q's grouped systematically and there will be subsequently a additional period for Bruno & Lars to send their anwers back to us. 
I hope all of you could be kind of patient .. I know it's difficult ... 😇
Best, Tom 

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39 minutes ago, DuckToller said:

That's correct and he is an active part in this Q & A with Purifi.
Thank you for your question about smartfi. 

Lars Risbo - although he is more commonly known for the development of the TACT - Millennium Digital Amplifier & his work for TI - has been in the seat for the newly developed driver PTT6.5W04-01A , that offers a "breakthrough" in the optimization of "the various distortion mechanisms" which "translates into low intermodulation (IMD): clean, undistorted midrange even in the presence of a heavy bass."

I can just invite you to use this opportunity to find out more on the subject of long-stroke-drivers and "negligible" distortion. 

Best, Tom

 

Nice, some actual "marketing" that actually addresses real fundamental constraints/hurdles of transducer design on a technical level!

 

I particularly like that graph which shows the relative level of (in this case 2nd and 3rd order) distortion to the fundamental.  Makes one wonder about all the fretting we do around distortion in electronics (i.e. amps, dacs, etc.)...

 

 

 


Hey MQA, if it is not all $voodoo$, show us the math!

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2 hours ago, DuckToller said:

 

Hi psjug, please allow me to respond on the subject.
It is a matter of days to get the Q's grouped systematically and there will be subsequently a additional period for Bruno & Lars to send their anwers back to us. 
I hope all of you could be kind of patient .. I know it's difficult ... 😇
Best, Tom 

 

I just hope they answer my question.

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On 5/18/2019 at 12:36 AM, Rt66indierock said:

Will there be a reference amplifier design for the DIY market?

@Rt66indierock
You mean this one?
AFAIK the answer were already given in the article "Meeting the experts of Purifi in Munich" .

The "Eigentakt" should be available for "DIY audio segment" approximately end of the year, prices may be announced end of Q3/2019.  A "standard" I/O board may be supplied as well. And they are working on therir own SMPS solution.

Did you mean anything different with your question? If yes, it would be helpful to specify!

Best, Tom

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18 hours ago, crenca said:

Makes one wonder about all the fretting we do around distortion in electronics (i.e. amps, dacs, etc.)...

Thank you, Crenca,

would you like to extract your wondering into a phrase/questions for the Q &A?
Could be quite interesting to hear the opinion from industry experts on that subject!
Curious, Tom

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or the well regarded Benchmark amp...


"The overwhelming majority [of audiophiles] have very little knowledge, if any, about the most basic principles and operating characteristics of audio equipment. They often base their purchasing decisions on hearsay, and the preaching of media sages. Unfortunately, because of commercial considerations, much information is rooted in increasing revenue, not in assisting the audiophile. It seems as if the only requirements for becoming an "authority" in the world of audio is a keyboard."

-- Bruce Rozenblit of Transcendent Sound

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2 hours ago, Sagittarius said:

Some users have replaced those caps with metalized polypropylene caps (space on the board did not accommodate normal polyp. caps) and reported noticeable improvement in sound quality

Hi,

If you examine the following :

https://linearaudio.nl/cyril-batemans-capacitor-sound-articles

 

You will see the testing of distortion within capacitors - and Polyester did have higher than PP etc, distortion.

Regards,

Shadders.

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3 hours ago, Sagittarius said:

 

- Class D has achieved very low levels of distortion, but is it possible for class D amplifiers to continue their evolution into something close to a straight wire with gain, i.e. minimal phase shift in the audio band?
 

 

@Sagittarius, is this why some say that all class D amplifiers sound like music played through a DAC with a min phase filter selected?


Hey MQA, if it is not all $voodoo$, show us the math!

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29 minutes ago, Shadders said:

You will see the testing of distortion within capacitors - and Polyester did have higher than PP etc, distortion.

 

Is that for series or parallel connections?  Of course in Mr. Putzeys' designs distortion of the output filter is inside the feedback loop and would be corrected...


ROON: DSD 256-Signature Rendu optical--Buffalo PRO (ESS 9038) or DSC-2--Ncore 400 Stereo-Focus Audio FS888-JL E-112 sub-Nordost Tyr USB, Cardas Clear AC, XLR, & speaker cables-Synergistic Blue & Hi Fi Tuning Supreme Cu Fuses, Dark Matter system clarifiers.    Design/Build Consultant with Sonore

 

                                                                                                  SONORE computer audio

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1 minute ago, barrows said:

 

Is that for series or parallel connections?

Hi,

The distortion is proportional to the DC bias voltage across the capacitor, and also with no DC bias. D Self book on Active Filters also has results of Polyester capacitors producing distortion in circuit.

 

Regards,

Shadders.

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Of course all parts add distortion, at some level.  My question was concerning whether that test was done using the capacitors in series or parallel...

 I think most audiophiles already believe (understand) that in filter circuits polypropylene dielectric is better (and polystyrene better still, and teflon, maybe better still), and that foil caps are generally considered better than metalized (although advancements in metaled caps make that questionable these days).  Also, these dielectric differences depend on what frequencies things are operating at as well...

 

In Class D filter design, the size of the cap and its loop area may trump all other concerns for the performance of the amplifier as a whole.  Mr. Putzeys has mentioned many times that he pays extreme attention to loop areas.  Using large size capacitors in the output filter design of a class D amp is a no no...


ROON: DSD 256-Signature Rendu optical--Buffalo PRO (ESS 9038) or DSC-2--Ncore 400 Stereo-Focus Audio FS888-JL E-112 sub-Nordost Tyr USB, Cardas Clear AC, XLR, & speaker cables-Synergistic Blue & Hi Fi Tuning Supreme Cu Fuses, Dark Matter system clarifiers.    Design/Build Consultant with Sonore

 

                                                                                                  SONORE computer audio

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7 hours ago, crenca said:

If the answer is "yes/possibly", coming back to my original question, what is responsible for the "sound" of a really (really really) clean amplifier like the 1ET400A as compared to a well regarded Class A/B, or even a well regarded Class A SS amp?  Using are ears, we all can tell the characteristic "sound" of these amps, so what accounts for this beyond harmonic/non-harmonic distortion measurements?

 

Easy to answer that question: because no amplifier, or other link in a reproduction chain operates in isolation ... they are always part of a system - and the remaining weakest areas will dictate "what the sound is".

 

Why have planes fallen out of the sky, over the years? Is it because the engines, the wings, or the cockpit isn't "good enough"? None of these ... it's the areas that haven't been addressed or looked after properly that undermine the integrity of what the system, whether it's a plane or audio system, is supposed to do.

 

Easy to tell if planes are safe; just count the number that fall out of the sky each year - but much, much harder, so far, to assess rig playback - just saying one is nicer to listen to than another doesn't cut it, I'm afraid.


Frank

 

http://artofaudioconjuring.blogspot.com/

 

 

Ahhh, Mankind ... Porsche intellect, Trabant emotions ...

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1 hour ago, Shadders said:

Hi,

The distortion is proportional to the DC bias voltage across the capacitor, and also with no DC bias. D Self book on Active Filters also has results of Polyester capacitors producing distortion in circuit.

 

Regards,

Shadders.

 

Polyester capacitors?  This a new fashion thing? :)

 


Anyone who considers protocol unimportant has never dealt with a cat DAC.

Robert A. Heinlein

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40 minutes ago, barrows said:

 

Apparently the Mola Mola Kaluga monoblocks use a different type capacitor in the output filter which Bruno only describes as "monolithic"...

 

Ceramic capacitors maybe?


Hey MQA, if it is not all $voodoo$, show us the math!

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15 hours ago, crenca said:

 

Ceramic capacitors maybe?

Ha Ha.

Don't forget class 1 ceramics, very stable, low drift, just low values available in SMD.

16 hours ago, barrows said:

@marce, typically, Mr. Putzeys' class D designs use box type polyester capacitors.  As I recall, for example, the NC-400 modules have three Wima polyester caps totaling about 2 µF in the output filter (parallel devices).  Some folks have modded these to slightly larger Wima Polypropylene parts and reported good subjective improvements.

Without gear to fully measure the results of such experiments I would not risk this mod myself.  Wima has a newer size polypro cap that should fit fine, although I have never found stock of that part...

 

Apparently the Mola Mola Kaluga monoblocks use a different type capacitor in the output filter which Bruno only describes as "monolithic"...

Cheers Barrows.

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Anyone with some basic electronic design knowledge can put together a class A or A/B amplifier in the garage. It might not sound so great but you will get sound. Class D is much more complex and only very few designers are really trying. Mr Putzeys is a great designer with a brilliant mind but what is stopping more designers from coming up with competitive solutions? It appears that we have far more rocket scientists than what we have class D designers. Even the large audio brand buy readymade class D modules and put them into their amplifiers. Why aren't they trying to produce their own class D solutions? I think we would see a faster evolvement of class D amplification if there were more competition.

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