Purifi EVAL1 EIGENTAKT Class D Amp Designs

[tomchr]

since my Purifi amp is a typical stereo amp the connectors must be 2- pole.

Not necessarily. It's pretty common to use 4-pole connectors in stereo amps. Benchmark does it. I do too.

I wonder why Purifi would supply this Eigentakt kit thing with professional connectors instead of the regular binding posts.

Because it's an engineering evaluation module, not a finished consumer audio amp.

The amp you show is by VTV. Why not ask them whether the speakON connectors are 2-pole or 4-pole?

Tom

 

[peng]

Not necessarily. It's pretty common to use 4-pole connectors in stereo amps. Benchmark does it. I do too.


Because it's an engineering evaluation module, not a finished consumer audio amp.

The amp you show is by VTV. Why not ask them whether the speakON connectors are 2-pole or 4-pole?

Tom

Good idea, thanks.

 

[JayGilb]

I have written that it seems so. According to the test report, the T+A scored more sound points than the NAD C298.

'A high damping factor tends to produce a more clearly defined, very precise and analytical sound image, whereas a reduced damping factor produces a more warm and softer sound image.' <- extract from the manual

@Bruno Putzeys
What are the advantages of this new implementation of the purifi modules?

Who wouldn't want "a more clearly defined, very precise and analytical sound image" ?
I can patch in any number of analog or digital effects to add a pleasant sounding distortion.

 

[BlackTalon]

Good idea, thanks.

I bought these from the Neutrik Store on Amazon's US site: Neutrik NL4FX 4-Pole speakON Cable Connector

They work fine with our VTV Eval amp

 

[restorer-john]

I think the confusion is about the 2-pole vs the 4-pole type of speakON.

Throw out those silly 2 pin and 4 pin Speakons and go with the 8 pin Speakon. 30A per contact!

 

[Digital_Thor]

Throw out those silly 2 pin and 4 pin Speakons and go with the 8 pin Speakon. 30A per contact!

I can only find the following, which claim that all Speakons are rated at minimum 30A:
https://en.wikipedia.org/wiki/Speakon_connector

 

[restorer-john]

I can only find the following, which claim that all Speakons are rated at minimum 30A:
https://en.wikipedia.org/wiki/Speakon_connector

Sure, but you have 8 contacts at 30A each. Somehow, I can't see that happening. 240 Amperes continuous through those plastic connectors...

Fire brigade anyone?

 

[Digital_Thor]

Sure, but you have 8 contacts at 30A each. Somehow, I can't see that happening. 240 Amperes continuous through those plastic connectors...

Fire brigade anyone?

Maybe.... but after some research... I found this much more in-depth overview data sheet from Mouser:
https://www.mouser.com/pdfDocs/03NEUTRIKPGE-speakONConnectors-201907-V201.pdf
Individual specs from the 4 pole I use - NL4FX:
https://www.neutrik.com/en/product/nl4fx

If the electrical resistance in the contacts are 0,002 ohms, then by U= R * I, we get a voltage drop of 0,002 * 40A = 0,08V, and P = U * I, so 0,08V * 40A = 3,2W of heat - if we pull 40A constantly - because these calculations only hold water in constant current draw, and not when adding frequency, like music - which again make sense, why Neutrik clearly states the following:

"speakON is NOT to be used as an AC mains or power supply connector!"

So I believe that the fire might start in the speaker coil and not the Speakons - if we really crank it way up

 

[peng]

My VTV Eigentakt Purifi amp's blue LED light is on as long as the power switch is on whether the standby switch is on or not whereas my Hypex NC502MP's LED is on only if the standby switch is off. Any comments on which one makes more sense?

 

[litemotiv]

A big advantage is the switchable damping factor!

I have the amp in question here (T+A A200), the damping factor setting noticeably changes how fast the amp sounds, another term to use perhaps could be how dry (or wet) it sounds.

The standard high damping factor sounds faster but also more dry, and some people who are used to more traditional amplifiers with a lower damping may not prefer this.

The lower damping factor sounds more like a traditional A/B implementation, meaning it sounds a little bit wetter, which could also be described as having a bit more 'weight'.

The differences are not huge but they are audible and it's a nice option to have available on an amp.

 

[pogo]

The differences are not huge but they are audible and it's a nice option to have available on an amp.

Which speakers have you already operated with the A200? I have made the experience that especially with potent speakers at higher DF the sound is not so mushy. Of course, this is very design-dependent and also a matter of taste.
In addition, my room modes are excited with less unnecessary energy, which in turn leads to less DSP correction and also preserves more details.

 

[litemotiv]

@pogo yes that is similar to my experience. I have currently only used Spendor A4 floorstanders with the A200. They sound a little more thumpy with the lower damping (comparable to my previous A/B amp), and cleaner / more nimble with the higher damping. I have a sub that i dial in slightly more with the higher damping to achieve a balance that i subjectively like (+2db at the crossover of 45hz).

I have only compared sighted though and have not done any ABX or additional measurements at this point.

 

[mocenigo]

Would probably be the ultimate Purifi Eigentact build.

I use his buffer. The resulting sound quality is in fact ultimate.

 

[Vhond]

Follow mode

 

[litemotiv]

Follow mode

You don't need to reply to the thread for that, you can simply click the Watch button at the top of the page.

 

[Gorgonzola]

I'm m looking for persons who have purchased the Purifi EVAL1 EIGENTAKT based systems and any build mods. I'm looking for a Canadian Supplier with track record. I live in Canada and have only found VTV so far.

I'm planning on using a VTV Purifi type amplifier as a front left and right Channel amplifier connected via XLR to a Yamaha 3080 AVR.

FYI, the Purifi EVAL1 EIGENTAKT setup is now shipping in the NAD C298 (similar to NAD M33 in theory) with what looks like a custom buffer power supply. I have only seen pics and have not done a teardown with one yet. It's price is $2,899.00 CAN which seems steep for NAD stuff.

Please share your experiences.

I'm well pleased with my VTV Purifi stereo with VTV buffer and Sparkos SS3602 op amps. However I bought this before the EVAL-1 version was available with is about US$500 cheaper, (less the price of Speakon connectors which you might need).

VTV isn't last word in fine construction but has proven completely reliable as well as excellent preforming. Warren Coleman bent over backwards with personal support re. an issue which was largely of my own making.

Meanwhile, though the VTV EVAL-1 version is cheaper, I don't thing the NAD C298 at Cdn$ 2900, (about US$ 2300), is outrageous by any means given the major brand name and the extra features it has including bridging, not to mention official certifications.

As for Neurochrome, I'd be delighted to own a Modulus-286 amp but I'm not up the DIY skill & effort involved. A beautiful custom stereo amp such that I saw here at ASR built by @tomchr himself would run a lot more money than VTV or NAD.

 

[litemotiv]

I don't thing the NAD C298 at Cdn$ 2900, (about US$ 2300), is outrageous by any means given the major brand name and the extra features it has including bridging, not to mention official certifications.

The NAD also has auto input sensing (the BoXem and T+A models do as well), which i think is a big selling point.

 

[Stefan]

My own implementation of the Purifi modules was recently subjectively reviewed against two other amplifiers using different technologies, but also at different price points.
Very well written and documented, several pages, all sort of musics listened, nice to read.
Summary in half a line: the most expensive sounds the best, the least expensive sounds the worst. Bad luck for me, my amplifier was the least expensive . What was particularly hard to swallow was that I consider one of the two other amplifiers as "$hit packed in golden paper" and it was supposed to sound better.

I also would be highly interested on this, perhaps a PM can point me in the right direction?

 

[amper42]

Meanwhile, though the VTV EVAL-1 version is cheaper, I don't thing the NAD C298 at Cdn$ 2900, (about US$ 2300), is outrageous by any means given the major brand name and the extra features it has including bridging, not to mention official certifications.

To me the NAD298 is outrageously priced. Can't imagine spending $2300 on a Purifi amp when you can buy one for half that price that does the job. Or you can spend $1700 on the March Audio P452, which seems high to me too. People can argue it's more expensive because it has "features" but most users just need an amp that turns on. You don't need variable gain, auto sensing, line out, bridge or other gizmo's that simply offer more parts to break. A simple build with quality Purifi components is best for most. Save the other $1000 toward a great pair of speakers.

 

[tomchr]

Summary in half a line: the most expensive sounds the best, the least expensive sounds the worst. Bad luck for me, my amplifier was the least expensive . What was particularly hard to swallow was that I consider one of the two other amplifiers as "$hit packed in golden paper" and it was supposed to sound better.

Olive & Toole found something similar in their research: When the prices are known the expensive gear is perceived as better sounding. In blind testing the gear that measures better (at least to a point) is judged as better sounding. Harman Kardon used to make their research public but sadly they pulled it some years back. You'll have to trawl through Sean Olive's blog or AES papers to find it.

They also found that Harman employees found Harman gear to sound better in sighted trials. Humans... Not rational critters.

Tom