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I have been considering the VTV / Purifi amp, and this review is quite helpful. The buffer options have also been in question. There are other players I'm looking at that don't offer the buffer option and use a different power supply—the NAD C298 and the March P452, both Purifi based stereo amplifiers.
Except now VTV makes a copy of the Purifi Eigentact for l.t. $1000 that uses the exact same setup as the prototype Amir reviewed 2 years ago, and it costs less than the Hypex. Moreover it costs less than the components (Ghent case, Hypex Smps, Purifi Eval 1) needed to assemble this as a diy.
That's the one to buy IMHO. Moreover, it can be hot-rodded to bypass the input buffer which increases Sinad to 108db--second only to the Benchmark, so why anyone would want a custom buffer at extra cost that any number of reviews show degrades performance, is a mystery to me.
At the time I decided to buy mine, Ghent did not have a dedicated case, so I bought the 300 mm wide case which he designated for the Hypex NC 400 stereo build, and had a custom case back fabricated for it at a local metalwork shop. And then I had problems with getting the Hypex Smps working. And there were covid related parts stock outs b/c my project was started in May 2020. All in all it took me longer than expected and it cost me more than expected b/c of the need to send components back to Hypex and another person for Smps repair.
In the end I got a great amp, but my advice to anyone looking to go the Purifi route is just buy the one from VTV that uses Purifi's input module and get the best performer for the lowest cost.
I think this VTV Purifi implementation offers great value. With that said, especially after viewing @amirm's teardown pics of the VTV, I'm especially pleased to have plunked down an extra 10 Benjamins for the NAD C298.
I incorrectly labeled this amp as using 990EnH but it was actually the 994EnH. I changed the title and a few places to indicate this in the review. Sorry about that.
how can someone mess such a straight forward design?
The 'reference' design literally looked like anyone can do it with access to documentation from Purifi.
the THD+N frequency dependency is just nasty, the whole point behind buying a 2000$ Purifi amp is to have Class D power that does not exhibit such behavior.
I looked into the DIY Purifi kits but it seems that you can't buy it unless you are a company that they would approve. For an individual, even if they would sell it to you directly, by the time you pay for shipping, taxes and import duties on top of the likely much highly price than the likes of VTV and Audiophonics, I suspect it would probably costs you more. It would be more fun DIY though.
I think you nailed it with the lack of any true testing to catch problems before he ships. It is nowhere close to an AP, but have eliminated and/or improved my builds using a QuantAsylum QA401. It is discontinued but the QA402 is only $500.
Have been pretty surprised how slight wiring differences can make a significant improvement to lower noise in an amplifier.
Hello Rick, I am very interested in doing some basic measurements and would need some help before I order one. Just a few questions if you don't mind:
- To measure THD+N, FR, SNR, FFT, aside from the QA402, what else would I need aside from obviously a multimeter, example: multimeter, power supply?
- Does the unit come with the necessary wiring harness, connectors etc.?
- Any instructions included, written, video, youtube links etc.?
I may end up getting a VTV (Eval1) amp so I probably need a QA402 in case I find it necessary to do some of the minor mods you have done that improved a few dB on noise (if I remember right and not confused you with someone else..)
Hello Rick, I am very interested in doing some basic measurements and would need some help before I order one. Just a few questions if you don't mind:
- To measure THD+N, FR, SNR, FFT, aside from the QA402, what else would I need aside from obviously a multimeter, example: multimeter, power supply?
- Does the unit come with the necessary wiring harness, connectors etc.?
- Any instructions included, written, video, youtube links etc.?
I may end up getting a VTV (Eval1) amp so I probably need a QA402 in case I find it necessary to do some of the minor mods you have done that improved a few dB on noise (if I remember right and not confused you with someone else..)
First, the QuantAsylum instructions are pretty good and, while you could do with dummy load resistors, I own a QA450 too. The QA450 is convenient, but not able to handle driving more than couple hundred watt amp to clipping. The rest of the parts are fairly inexpensive.
Since off topic for this thread, will post the other parts needed on a new thread.
First, the QuantAsylum instructions are pretty good and, while you could do with dummy load resistors, I own a QA471 too. The QA471 is convenient, but not able to handle driving more than couple hundred watt amp to clipping. The rest of the parts are fairly inexpensive.
Since off topic for this thread, will post the other parts needed on a new thread.
Btw, if after looking into it, you rather not spend the money on the QA402, can arrange to have your amp shipped to me and will measure and as I have done for others. I only charge $20 for the analysis. If I find issues, can either recommend a fix or offer to fix for a small fee.
Btw, if after looking into it, you rather not spend the money on the QA402, can arrange to have your amp shipped to me and will measure and as I have done for others. I only charge $20 for the analysis. If I find issues, can either recommend a fix or offer to fix for a small fee.