Right now I have two pair of Mono amplifiers. Hypex NC400 and Purifi monoblocks with individual Hypex 1200/400 SMPS.
I borrowed Hypex NC400 from a friend.
If I compare I like Hypex NC400 to be sounding much better. Which should not be the case. It means there is some problem somewhere in implementation.
Hypex has everything from Hypex including SMPS.
Where as in case of Purifi we are using third party buffer and Opamps. There probably could be mismatch somewhere.
When so many big companies like NAD and others are using Purify module it has to be very good.
NC400 is sounding terrific on the same system . Dilemma ?
Well, I am not very sure about VTV's prowess at buffer design, but they might have just cloned somebody else's, let's hope (!) it is Apollon's and not Nord's (similar circuit, but Nord has much better routing).
I think the Sparkos are the main culprit. The "pro" socket ones are better than the DIP8 ones, but they are unengaging and dull. The Sonic Imagery are much better in my humble and subjective. I do not know, but maybe you could swap them or retrofit the Neurochrome Buffer instead. One of these two alternatives should bring your monos to a different level.
Here is an image of VTV's input buffer.
VTV Amplifier Custom Input Buffer Hypex Purifi NC500 NC1200 NC2K USA SPARKOS | eBay
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I got my Purifi Monoblocks amps from VTV with their input buffers and Sparkos 2590. I have had over 300 hours on them.
The sound is not engaging like NC400.
It’s a bit too smooth and missing in dynamics and images are not focussed. It could be because of Sparkos as some of you have mentioned. I also suspect this Dip connection may not be ideal for amplifier buffers as they might not be giving solid contact like soldering. Also Sparkos have a smoother sound compared to sonic imagery.
So I have two options it appears. Try Sonic Imagery and hope
for good results.
Or try new buffer from Purifi for their Eval 2 mono block modules expected shortly.
Can anyone recommend any other buffer and opamps that has received good reviews.
With Neurochrome buffer I will not be able to use Sparkos or Sonic Imagery. Am I correct. They also have a voltage regulator option . What’s that ?
So what all do I need if I go for Neurochrome option.
That is correct. This board uses the same opamps that are used with Neurochrome's Universal Buffer board, which have a fair amount of drive capability and should be a good match for the Purifi module. Also, this board has a differential receiver to remove common mode noise prior to driving the Purifi board. This is different than some of the other buffers which handle the positive and negative legs separately and rely on the Purifi module to do common mode rejection. I suspect removing the common mode signals prior to the buffer gain makes more sense, but I can't say for sure.
The Neurochrome board has the option of adding voltage regulators. These are implemented using daughter boards, so different regulator options can be used (such as the Sparkos regulators).
Alternatively, you can use the regulated output from your SMPS. I believe the VTV buffer includes regulators and assumes the SMPS is set up to use the unregulated outputs. So if you choose to not add regulators to the Neurochrome board, you'll have to change the jumper(s) on the SMPS to use regulated outputs for the OpAmp supply.
The Neurochrome board has the option of adding voltage regulators. These are implemented using daughter boards, so different regulator options can be used (such as the Sparkos regulators).
Alternatively, you can use the regulated output from your SMPS. I believe the VTV buffer includes regulators and assumes the SMPS is set up to use the unregulated outputs. So if you choose to not add regulators to the Neurochrome board, you'll have to change the jumper(s) on the SMPS to use regulated outputs for the OpAmp supply.
With the VTV...
With the VTV boards you have the ultimate flexibility in choosing your Opamps, so I would keep your VTV boards, and try some different opamps in the sockets. I suspect you will have excellent results with the Sopnic Imagery 990 pro style opamp. The best option for plug in opamps is probably the Weiss OP-2, but they are quite expensive. I do not think there is a real need to swap out the entire input board assemblies... The VTV boards already have very good voltage regulators onboard. And make sure your SMPS 1200 are set to output the un-regulated power supply to the input boards, otherwise things are not working correctly, and your input circuitry is not getting the correct voltage.
With the VTV boards you have the ultimate flexibility in choosing your Opamps, so I would keep your VTV boards, and try some different opamps in the sockets. I suspect you will have excellent results with the Sopnic Imagery 990 pro style opamp. The best option for plug in opamps is probably the Weiss OP-2, but they are quite expensive. I do not think there is a real need to swap out the entire input board assemblies... The VTV boards already have very good voltage regulators onboard. And make sure your SMPS 1200 are set to output the un-regulated power supply to the input boards, otherwise things are not working correctly, and your input circuitry is not getting the correct voltage.
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My bet would be the Purifi buffers. If they can make such fine amps I'm sure they have the competence and inclination to make an equal superior input stage. You know like Nc400 input stage - I doubt that they would make something poorer than that - even if in this case it's built with OP amps.
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Hmmm..
While I agree that Bruno Putzeys can certainly design a very, very good input stage for the Purifi module, this does not mean that the current Eval board is that input stage. The Eval board was designed to be a simple way to evaluate the board, and never meant to be the "best" possible input stage.
Most notably, the 1612 opamps used, while an excellent part, is being pushed quite close to its limits in terms of both voltage swing and current delivery in this application (I own the Purifi eval module and currently use it). I have a suspicion that a circuit with a bit more drive capability and class A current delivery might improve upon what the Eval board is capable of.
With Mola Mola, Bruno designed a discrete input stage for their amps, and for the NC-400 module he also designed a discrete input stage. And certainly the Mola Mola amps, for example, sound fantastic by any measure.
The pro type opamps like the Sonic Imagery 990, and the Weiss OPB-2 feature a lot more current capability at nearly the same distortion and noise performance of the OPA 1612.
While I agree that Bruno Putzeys can certainly design a very, very good input stage for the Purifi module, this does not mean that the current Eval board is that input stage. The Eval board was designed to be a simple way to evaluate the board, and never meant to be the "best" possible input stage.
Most notably, the 1612 opamps used, while an excellent part, is being pushed quite close to its limits in terms of both voltage swing and current delivery in this application (I own the Purifi eval module and currently use it). I have a suspicion that a circuit with a bit more drive capability and class A current delivery might improve upon what the Eval board is capable of.
With Mola Mola, Bruno designed a discrete input stage for their amps, and for the NC-400 module he also designed a discrete input stage. And certainly the Mola Mola amps, for example, sound fantastic by any measure.
The pro type opamps like the Sonic Imagery 990, and the Weiss OPB-2 feature a lot more current capability at nearly the same distortion and noise performance of the OPA 1612.
I agree with @barrows that the Eval board is not going to deliver the best possible performance. The current Eval board is about as simple as you could make it and still delivery the necessary gain and functionality. It's possible you'll get performance that is comparable to the NC400 (I've never heard this module), but I'm confident you can do a lot better.
Purifi publishes the current Eval board schematics - you can take a look for yourself to see that it is very basic and does not use premium parts. I don't think Purifi expects this board to be used for a production amp (or even a DIY amp). It's intended to allow prospective customers to have something they can use to test the basic performance of the Purifi modules at a minimum cost, prior to investing in their own design.
If you're looking for an input board that allows the Purifi module to reach it's full potential without introducing any of it's own sonic character, the Neurochrome board is probably your best bet. But you might get a richer and more involving sound by trying some of the other op amp options on the VTV board.
My experience with the Sonic Imagery op amps is that they produce a detailed and airy sound stage. Compared to the Sparkos (in an NC500 amp), they were more forward and revealing. In the system I had at the time, I actually preferred the Sparkos, but that system was a bit edgy sounding to start with and the Sparkos helped mellow things out a bit.
I haven't tried the Weiss devices, but they look interesting (if a bit pricey).
Purifi publishes the current Eval board schematics - you can take a look for yourself to see that it is very basic and does not use premium parts. I don't think Purifi expects this board to be used for a production amp (or even a DIY amp). It's intended to allow prospective customers to have something they can use to test the basic performance of the Purifi modules at a minimum cost, prior to investing in their own design.
If you're looking for an input board that allows the Purifi module to reach it's full potential without introducing any of it's own sonic character, the Neurochrome board is probably your best bet. But you might get a richer and more involving sound by trying some of the other op amp options on the VTV board.
My experience with the Sonic Imagery op amps is that they produce a detailed and airy sound stage. Compared to the Sparkos (in an NC500 amp), they were more forward and revealing. In the system I had at the time, I actually preferred the Sparkos, but that system was a bit edgy sounding to start with and the Sparkos helped mellow things out a bit.
I haven't tried the Weiss devices, but they look interesting (if a bit pricey).
It's less expensive, and the simpler circuit makes it easier for OEMs to determine the essential functionality. Purifi's primary market is OEMs. OEMs need to be able to provide their distinctive value-add.
If Purifi provided an interface/buffer board that was the best Putzeys could design, not only would it be more expensive (perhaps considerably), but it would leave much less opportunity for OEMs to differentiate their products.
If Purifi provided an interface/buffer board that was the best Putzeys could design, not only would it be more expensive (perhaps considerably), but it would leave much less opportunity for OEMs to differentiate their products.
Straight from Bruno:
from: PURIFI Audio and the Audiophile Style reader's Q&A with Lars Risbo & Bruno Putzeys
The way I read it - if you want max performance, skip the buffer
from: PURIFI Audio and the Audiophile Style reader's Q&A with Lars Risbo & Bruno Putzeys
The way I read it - if you want max performance, skip the buffer
But this "basic performance" still did pretty good in ASR's measurements. Actually so good that there's very little sense to "upgrade" it with 3rd party attempts to make it better. Sure you can tinker with those and make it "different" but not actually any better.
Straight from Bruno:
from: PURIFI Audio and the Audiophile Style reader's Q&A with Lars Risbo & Bruno Putzeys
The way I read it - if you want max performance, skip the buffer
Well, if you have 10-15 dB of gain to spare in your system - fine!!
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