MZX Audio PHO-NR1 Phono Stage Review

[NicS]

Sort of, see the product sheet on their website for she full set of combinations.

Big Aphex Twin fan BTW….

 

[sceptical1]

It is a shame that the poll results indicate no interest in the actual performance of the device rather a cursory look at the conclusions and this when no mc testing was performed.

When noise is the primary engineering problem to be overcome designing a mic preamp for mc is quite clever. Fully balanced circuitry, 72db gain, 1k input, -100db cmrr, xlr in/out, sounds like a mic preamp to me. Coincidentally a 48v ps, there must be a phantom power connection hiding in there someplace. That Meanwell ps is a nice looking item.

Of course there is 50k input available (I thought not, default with 60p cap loading) and also both 100R switches parallel for 50R needed for those very low output (low impedance) mc cartridges.

Now that the eq problem was easily taken care of there is no phono preamp that can surpass this on specs, thanks to the smps 6-10db quieter than the excellent Fidler and being fully balanced no even order thd. and the commandeered 2 stage riaa circuit guarantees tracking to within 0.2db on every preamp using standard 2% tolerance caps.

For the price, your 5 figure+ snake oil preamps touted at "that other site" will prove to be even more of an embarassment.
What measurements show and realizing that same performance in use are why a balanced configuration (done right) and balanced inputs are the bare minimum for problem free vinyl playback under any conditions, rfi, ground loops, maybe even compliance related resonances if he fixed the hi pass filter.
Too bad about the Buckeye style enclosure. If you think this is excusable look at what Audio Smile can do with the LBM at half the price. Same garage, same innovative designer, one is attractive and one is butt ugly. It must be intentional. I'm not falling for the 'we spend all the money on the internals to save YOU our valued customers every precious dollar possible". Aesthetics count when I want to show off.

 

[Bland_username42069]

4 figures and internal dip switches is a tough sell. At some point ergonomics has to come into the equation

 

[amirm]

It is a shame that the poll results indicate no interest in the actual performance of the device rather a cursory look at the conclusions and this when no mc testing was performed.

There is nothing cursory about this:

As a minimum this should have been documented.

 

[amirm]

In view of all that, I'm really puzzled you are now quite reluctant to measure the MZX in the use case for which it appears to have been optimized -- namely, with a low-output MC cartridge.

The gain setting would not have an impact on the overall review. Same frequency response error would be there regardless. With the tested gain being kind of in between MM and MC, the evaluation was more or less completed for both. I was not going to double the work just because.

 

[sceptical1]

The design concept is enough for me to interpret the ultimate performance of this device. Your MM measurements prove this as being the best phono device tested so far, as you say, the measurements are compelling so, MC performance will be as good or better than anything else.

By cursory I assumed it was plainly obvious that I was talking about the response to the poll by members who know so little about audio as to skew the results by being dumbstruck by a completely inaudible, measurably insignificant and easily remedied (already done by the designer) out of band abberation exactly the same as a class d non pffb high frequency peak of 1.5 db just above 20khz where in that case is not worthy of any concern

Your not recommended conclusion based solely on the contrived opinion of a glaring defect being present didn't help matters when the younger, newer members are so impressionable.
I don't even care that you refuse to make a checklist so you won't miss a part of your normal test procedure. Except if a product is designed to address absolute transparency for an intended function and what the result would be under those conditions (0.5mv, 50 ohms, 62db gain) is completely ignored. Or, the LBM has a method specially designed to reduce port resonances that can't be confirmed because you forgot to measure that port output we could care less about on the last 200 reviews where it was 20db below the signal level, by how much did the LBM improve it. Who knows.

On to more important things: JAYs 4 LADs 2, bottom 7th

 

[Ein]

The design concept is enough for me to interpret the ultimate performance of this device. Your MM measurements prove this as being the best phono device tested so far, as you say, the measurements are compelling so, MC performance will be as good or better than anything else.

By cursory I assumed it was plainly obvious that I was talking about the response to the poll by members who know so little about audio as to skew the results by being dumbstruck by a completely inaudible, measurably insignificant and easily remedied (already done by the designer) out of band abberation exactly the same as a class d non pffb high frequency peak of 1.5 db just above 20khz where in that case is not worthy of any concern

Your not recommended conclusion based solely on the contrived opinion of a glaring defect being present didn't help matters when the younger, newer members are so impressionable.
I don't even care that you refuse to make a checklist so you won't miss a part of your normal test procedure. Except if a product is designed to address absolute transparency for an intended function and what the result would be under those conditions (0.5mv, 50 ohms, 62db gain) is completely ignored. Or, the LBM has a method specially designed to reduce port resonances that can't be confirmed because you forgot to measure that port output we could care less about on the last 200 reviews where it was 20db below the signal level, by how much did the LBM improve it. Who knows.

On to more important things: JAYs 4 LADs 2, bottom 7th

You are right. I'm vinyl man. That thing is an achievement. No less, no more. Very rare form designed to offer a level without any "buts". In my opinion happy pink here and after minor upgrade GREAT.

 

[jareinertson]

It's nice to see someone use EMPIRICAL (a fact that you know is occuring but have no measurement proof to present to others).
There have been times (such as at my mother's house) when I needed to run 12 or so feet from the DUAL 1229 turntable to the APT/Holman preamp (one side of the fireplace [at this time not being used as a fireplace] to the other). Instead of converting to balanced, I just run about 3 ft. to an ART Phono Pre whose line level output I run about 10 ft. into a line in on the APT. Because I had the ART on hand, it was a quick & simple solution that did not seem to have any negative results.
So, since I have no pre-amps (or other gear) that have balanced inputs, I'll wait. But I do want to try this conversion on my Technics SL-M3. Hopefully I will obtain a Micheal Fidler preamp next year with ballanced inputs so that I have a reson to do this.

It's a hobby, at least for me & I enjoy my personal experiments, for better or worse.

It's nice to see someone use EMPIRICAL (a fact that you know is occuring but have no measurement proof to present to others).
There have been times (such as at my mother's house) when I needed to run 12 or so feet from the DUAL 1229 turntable to the APT/Holman preamp (one side of the fireplace [at this time not being used as a fireplace] to the other). Instead of converting to balanced, I just run about 3 ft. to an ART Phono Pre whose line level output I run about 10 ft. into a line in on the APT. Because I had the ART on hand, it was a quick & simple solution that did not seem to have any negative results.
So, since I have no pre-amps (or other gear) that have balanced inputs, I'll wait. But I do want to try this conversion on my Technics SL-M3. Hopefully I will obtain a Micheal Fidler preamp next year with ballanced inputs so that I have a reson to do this.
It's a hobby, at least for me & I enjoy my personal experiments, for better or worse.

Nice to see an APT/ Holman preamp mentioned and still in use. I enjoyed mine until it died some years ago…

 

[EJ3]

Nice to see an APT/ Holman preamp mentioned and still in use. I enjoyed mine until it died some years ago…

They are pretty easy to have rebuilt, if you still have it.

 

[jareinertson]

They are pretty easy to have rebuilt, if you still have it.

Sadly it went away years and my APT Model 1 power amp as well. Sad to see them gone but I’m very happy with the Mark Levinson units that replaced them.

 

[ryanmh1]

The design concept is enough for me to interpret the ultimate performance of this device. Your MM measurements prove this as being the best phono device tested so far, as you say, the measurements are compelling so, MC performance will be as good or better than anything else.

By cursory I assumed it was plainly obvious that I was talking about the response to the poll by members who know so little about audio as to skew the results by being dumbstruck by a completely inaudible, measurably insignificant and easily remedied (already done by the designer) out of band abberation exactly the same as a class d non pffb high frequency peak of 1.5 db just above 20khz where in that case is not worthy of any concern

Your not recommended conclusion based solely on the contrived opinion of a glaring defect being present didn't help matters when the younger, newer members are so impressionable.
I don't even care that you refuse to make a checklist so you won't miss a part of your normal test procedure. Except if a product is designed to address absolute transparency for an intended function and what the result would be under those conditions (0.5mv, 50 ohms, 62db gain) is completely ignored. Or, the LBM has a method specially designed to reduce port resonances that can't be confirmed because you forgot to measure that port output we could care less about on the last 200 reviews where it was 20db below the signal level, by how much did the LBM improve it. Who knows.

On to more important things: JAYs 4 LADs 2, bottom 7th

I'm a bit late to this party, but that's all well said. What you say is also also why I basically quit bothering with reading or posting much. The measurements are good to have, but the interpretation of them by many here is, generally speaking, quite often well off the mark and sloppy. Couple that with an apparent lack of curiosity by many about much of anything short of SINAD (or at least, an inordinate focus on it) and it's just exhausting. Pages and pages of people often praising absolute crap (or ripping on excellent products), and often completely missing what actually matters. Instead of fostering technical knowledge, everything often turns into a THD+N d*** measuring contest. But I digress and will stop venting now....

So, do I fault a designer for (possibly) trying to rig his way up the SINAD chart a bit? Nah. Everyone else has been doing it for years and getting away with it, often egregiously. He should have too.

Now, here's where I am going to disagree with you. That "aberration" isn't exactly out of band. That said, I also don't think it really matters or will bother anyone. And it's easily enough fixed. 'Nuf said.

But, I do think there is something that is concerning here, that was not exactly overlooked, but misunderstood in the review text, and which managed to avoid comment thus far. I'm posing it because I think the designer cares and wants to produce a better product. First, to be clear, this thing is wicked good in many respects and very clever. But I'm not so convinced the overload is "fine" at all, and it arguably fails to be adequate when coupled with the otherwise clever gain structure. The output of the phono cartridge does not vary. There's no magic switch to turn down the cartridge. So why does the higher gain ("Don't comapre [sic] to 45dB gain of other preamps") matter at all unless you're only going to use this with 2.5mV output cartridges? It doesn't. This makes no sense to me at all from a technical perspective. In it's lowest gain mode, this thing clips between 45mV and 50mV. At 10kHz it's losing the plot around 35mV OUTPUT from the cartridge. So, use it with a typical 5mV output cartridge and that cartridge is still going to whip along at whatever velocity it does, which will cause its output to go up, and the darn thing is still going to clip wherever it does. The only way to avoid that is a 2.5mV cartridge. So no, I don't think that is fine, and it's an unfortunate side effect of using the cranked up gain structure. That said, many "high end" phono preamps have gotten away with less. If somehow I'm wrong about this, I stand happy to be corrected. [To be fair, I initially made the same mistake Amir did and tried to calculate what the overload would be at a normal 40dB gain, but what that would be is irrelevant because that cannot be]

In the end, this probably should have been reviewed as a moving coil only unit. It probably does fine there, but its performance as such a unit was not characterized. A complaint you already touched on. Personally, I would not buy this to pair with "standard" 5mV output cartridges. That's going to require either vastly more overload margin to be designed in, or changing over to an active RIAA implementation to avoid bleeding off so much overload margin as frequencies rise.

Now I feel bad for curb stomping this thing, which I started out really liking. But alas, it is what it is, and that is a preamp that is only barely adequate, at best, in terms of overload with a MM cartridge hooked to it. MC? Probably great.

 

[Billy Budapest]

Strange RIAA deviation, although we are talking about 1.5dB at 40Hz which shouldn’t be too audible. Otherwise, very good specs and great parts quality—I don’t expect problems with the caps down the line.

Had to give it a “fine” rather than a “great” due to that unfortunate low bass boost.

 

[amirm]

Strange RIAA deviation, although we are talking about 1.5dB at 40Hz which shouldn’t be too audible.

The challenge there is room modes. It is quite common to have one in 40 to 50 Hz. If so, this gets added to that, causing even more boominess.

 

[amirm]

I'm a bit late to this party, but that's all well said. What you say is also also why I basically quit bothering with reading or posting much. The measurements are good to have, but the interpretation of them by many here is, generally speaking, quite often well off the mark and sloppy. Couple that with an apparent lack of curiosity by many about much of anything short of SINAD (or at least, an inordinate focus on it) and it's just exhausting.

This frankly is a lot of nonsense. Every review without exception has this and that person saying everything that is measured is likely or guaranteed to be inaudible. It is so common as to be "exhausting" as I read the responses early on in the review.

Further, vocal members tend to also be knowledgeable about all the measurements and routinely comment on the rest.

Net, net, what you are saying are talking points created by anti-measurement folks. Every review has extensive set of measurements beyond SINAD. Even SINAD is accompanied by detailed FFT as to truly show the nature of SINAD.

Even if we were doing what you say, SINAD by itself is a mostly reliable indicator of the rest of measurements. It tends to be low when the designer hasn't measured, doesn't understand measurement, or its competition. You don't get good SINAD and then ignore everything else. Having good SINAD guarantees the company cares about transparency and true dedication to fidelity. So don't talk about it as if it is the color of the car.

 

[ryanmh1]

You don't get good SINAD and then ignore everything else. Having good SINAD guarantees the company cares about transparency and true dedication to fidelity. So don't talk about it as if it is the color of the car.

I didn't want to get into a debate over this, since it's already been proven over and over, but here we go... When it comes to phono stages, SINAD measurements are quite often window dressing, or the "color of the car", unless the measurements are done correctly. You do not do them correctly because you do not connect a cartridge load. To be fair, Soundstage doesn't do them right either, nor does Stereophile. IHF and CEA standards require a load, and for good reason.

That reason is that the moving magnet cartridge itself significantly degrades the signal to noise ratio, due to the source impedance and inductance. The only question is by how much. A FET input could be a little as a few dB. A bipolar input could range up to 18dB. I can't take credit for the quote, but basically, "measuring a phono stage with a cartridge load on the input is about as useful as measuring a power amplifier without a load on the output." It's useless data, unless you couple that with deep knowledge of the input stage components and topology. Even then, you're still left making educated guesses, which very few people are qualified to do.
IOW, once you're over about 70dB, "the chart" has no predictive utility regarding actual performance. And even then, it's no guarantee it can't get worse.

Worse, pretty much no moving magnet stage can ever get above around 78dB at 5mv or so with a cartridge connected and a standard 40dB gain stage (absent something like resistor cooling schemes).

If you want citations for any of this, I am more than happy to provide them, but I have to believe by now you know every last word of this is true.

So, having "good SINAD" doesn't mean squat. All it means in some $150 phono stage is that some guy likely grabbed a low noise bipolar, tossed it in there, and added a rudimentary level of PSU filtering. That "great" 82dB could easily drop to 72dB or even 65dB once a cartridge is connected. Note that I am not making audibility claims here. This strictly concerns engineering excellence.

All that said, the overload testing is useful (and often uncorrelated with SINAD in terms of being "good). And the SINAD testing does at least indicate a product probably is not worse than the test figure minus 10 to 18dB in the worst cases. So, there's that.

Before claiming this is all poppycock, PM Michael Fidler or someone else who designs phono stages and ask them if a word of this is wrong. I am happy to be proven completely incorrect on any of the above points.

I'll also note that you didn't take issue with my comments about overload margin of the PHO-NR1, so I assume there were no issues there, at least.

We all want the same thing here, which is engineering excellence with spurious and unprovable claim of audio electronics wizardry, so please don't take this the wrong way. I'm merely trying to be helpful.

 

[mike70]

IMHO, the more important facet on a phono stage is RIAA implementation.
2dB difference in some frequencies are worst than any other inaudible noise at normal volume from the listening position.