MZX Audio PHO-NR1 Phono Stage Review

[EJ3]

It looks like a very well designed device, except for one detail.

Since we endorse EQ adjustments for headphones, which can turn a “not recommended” headphone into a “recommended” one after EQ, why don’t we apply the same logic here?

I run MM only but:
Serious question: would a quality analog EQ be able to rectify this issue without mucking up something else (I have used analog EQ's in the past & they seemed to add noise & make things sound less dynamic [perhaps that was the particular units I was using] {my pre Amp has an independent prosessor loop})?
Not that I would spend this kind of money on a phono amp that was this flawed with the amount of gain and the FR (but those could be fixed).

 

[Doodski]

I run MM only but:
Serious question: would a quality analog EQ be able to rectify this issue without mucking up something else (I have used analog EQ's in the past & they seemed to add noise & make things sound less dynamic [perhaps that was the particular units I was using] {my pre Amp has an independent prosessor loop})?
Not that I would spend this kind of money on a phono amp that was this flawed with the amount of gain and the FR (but those could be fixed).

Analogue EQ/PEQs add a lot of hiss to the audio. It's the nature of having so many OP amps inside them.

 

[EJ3]

Analogue EQ/PEQs add a lot of hiss to the audio. It's the nature of having so many OP amps inside them.

Damn Hissing Snakes: some of them could actually be made to help but, unfortunately, I never owned one queit enough for me.

 

[Short38]

Any product review which begins with removing the top of the unit, then accessing dip switches followed by gain issues and a bass bump followed by a recommendation is a testament to the patience and generosity of the reviewer. One hopes the designer will return to the drawing board.

 

[LTig]

Would it be ridiculous for me to think that the designer has no idea that he is manufacturing a strictly MC phono preamp?

No.

High gain MC - 52db and 1k input
Low gain MC - 62db and 100r input
Very low gain MC - 72db and 100r input
Typical specs for a MM cartridge of 47k input and 40db gain do not exist for this preamp. Something weird is going on.

Not necessarily. In the old analog times line inputs were much more sensitive, say 150 .. 300 mV, hence 40 dB gain for MM phono preamps were sufficient. With CD players outputting 2V some amplifiers could not cope with it.

But those times are gone, and I expect every amplifier sold new since 1990 that its line input can handle 2V without clipping. With 52 dB gain and 5 mV input we get 2V output. This is perfect, because you don't need to change volume when switching between phono and digital sources with 2V analog output.

 

[Heinrich]

Is the input noise current of this pre optimized for MC or for MM? No switch for that, I assume.
Also, which pickup or turntable would support real balanced connections? Even pseudo-symmetry isn‘t easily achieved because of the high impedances involved with MM.

Can‘t vote, lacking data. The bass is a non-issue, though.

 

[mike70]

Looks well made and except for one issue, well designed. $1,200 and having to remove the cover to fiddle with dip switches is a non-starter for me. Why buy this over the Schiit balanced phono which has balanced and SE inputs and outputs and a remote for $399 - $499.

The Schiit doesn't have a noise in one channel (I think the right channel)? Or it was fixed?

 

[LTig]

Is the input noise current of this pre optimized for MC or for MM? No switch for that, I assume.

Difficult to say as we don't know what output impedance was used to feed the input. Usually it's too low.

Also, which pickup or turntable would support real balanced connections? Even pseudo-symmetry isn‘t easily achieved because of the high impedances involved with MM.

All pickups have balanced outputs (4 pins). It's the wiring to the TT cable which prevents or allows a balanced output. It's not too difficult to change this if needed.

 

[Heinrich]

Difficult to say as we don't know what output impedance was used to feed the input. Usually it's too low.

All pickups have balanced outputs (4 pins). It's the wiring to the TT cable which prevents or allows a balanced output. It's not too difficult to change this if needed.

We can buy MI pickups that mitigate self-noise and current induced noise. All in all the surface noise of even brand new LPs will swamp the pre‘s and MM‘s contribution anyway. As always, perfection isn‘t the best guideline, practicability is. I wish audio would follow basic engineering paradigms more closely.

Ya, measure it. Many pickups have two of the 4 connected, and at least with numerous Shure a shield is connected to that common point additionally. The platter might expect this configuration with its internal wiring. Balanced is non- standard. Maybe because of the noise penalty weighted against wire length in a clean environment combined with the lifted threshold of hearing in the bass. (When the standards were set, higher harmonics of the mains originated in fluorescent lamps driven by a simple ballast inductor, not common in regular households.)

 

[ampguy]

Im interested in a balanced out phono pre, but not sure if I need balanced ins. Have 3 tables, main is a marantz tt15, and the short rcas are hum free with a parks puffin and schiit mani.

 

[mike70]

Im interested in a balanced out phono pre, but not sure if I need balanced ins. Have 3 tables, main is a marantz tt15, and the short rcas are hum free with a parks puffin and schiit mani.

the cheapest available is the fiio zen phono ... and i think is the price / performance champ with balanced outputs.

 

[sceptical1]

Any product review which begins with removing the top of the unit, then accessing dip switches followed by gain issues and a bass bump followed by a recommendation is a testament to the patience and generosity of the reviewer. One hopes the designer will return to the drawing board.

You call this a chore? Buying new cables and xlrs, disassembling your turntable, soldering evrything, modifying the cartridge grounding and hoping you didn't mess up. Now that is a chore.

 

[wwenze]

I wonder if there is any point in additional mains filtering with a commercial Meanwell PSU.

The extra LC at the output seems redundant too

 

[NicS]

Im interested in a balanced out phono pre, but not sure if I need balanced ins. Have 3 tables, main is a marantz tt15, and the short rcas are hum free with a parks puffin and schiit mani.

This is my experience:

I have a Dynavector MC cartridge with a low output on an SME V tonearm. The base of the tonearm has a 4 pin socket so it’s relatively easy to change cable configurations. I made up a balanced cable and experimented using the balanced input of my phono pre-amp. These are my observations:

First, the signal strength increased. The output from the cartridge was significantly greater using the balanced cable. Second, the noise floor was significantly reduced. These are empirical observations. I have no way of measuring these differences.

Vinyl is an antiquated, deeply flawed method of sound reproduction. But since a chunk of the music I listen to only exists on vinyl, I persist with this format for that reason and of course a nostalgic attraction to the process. It’s an audio tweakers black hole of incremental improvements; the perfect expression of the law of diminishing returns.

The last big leap I’ve experienced in sound quality using this system was jumping from single ended to balanced input. It makes good logical sense and you can actually HEAR the difference, at the very least in terms of volume.

I’d recommend you give it a try if you can be bothered. Or forget all of this and just be happy with what you have, which is no doubt fabulous anyway.

 

[EJ3]

We can buy MI pickups that mitigate self-noise and current induced noise. All in all the surface noise of even brand new LPs will swamp the pre‘s and MM‘s contribution anyway. As always, perfection isn‘t the best guideline, practicability is. I wish audio would follow basic engineering paradigms more closely.

Ya, measure it. Many pickups have two of the 4 connected, and at least with numerous Shure a shield is connected to that common point additionally. The platter might expect this configuration with its internal wiring. Balanced is non- standard. Maybe because of the noise penalty weighted against wire length in a clean environment combined with the lifted threshold of hearing in the bass. (When the standards were set, higher harmonics of the mains originated in fluorescent lamps driven by a simple ballast inductor, not common in regular households.)

I do not know the area that you live in but in my area of the USA extensive travels throughout my life (FL, NC, SC, GA & TN [and the people that I know, whose homes I have been in]): flouresant lights were (at least since I started paying attention [when I was 6, in 1966) and are pretty common in the bathrooms (1 over the sink counter area) and kitchens (1 over the sink counter area) in at least 50% of the homes I have been in since then. And very common in the garages, many of which are now "man cave's" with the stereo.
When they get changed out these days, may times it's to leds. But these flourescents dont usually have many hours on them and the change over is happening at a slow pace. And some people prefer the flourescents (for several various reasons).
I would say that it would be unusual for me to be in a home that had ZERO flourescents.
In the sense that 95%+ of most homes lighting is not flourescent, you are correct.
But saying that it is not common, in my experience, that is not correct.

 

[EJ3]

This is my experience:

I have a Dynavector MC cartridge with a low output on an SME V tonearm. The base of the tonearm has a 4 pin socket so it’s relatively easy to change cable configurations. I made up a balanced cable and experimented using the balanced input of my phono pre-amp. These are my observations:

First, the signal strength increased. The output from the cartridge was significantly greater using the balanced cable. Second, the noise floor was significantly reduced. These are empirical observations. I have no way of measuring these differences.

Vinyl is an antiquated, deeply flawed method of sound reproduction. But since a chunk of the music I listen to only exists on vinyl, I persist with this format for that reason and of course a nostalgic attraction to the process. It’s an audio tweakers black hole of incremental improvements; the perfect expression of the law of diminishing returns.

The last big leap I’ve experienced in sound quality using this system was jumping from single ended to balanced input. It makes good logical sense and you can actually HEAR the difference, at the very least in terms of volume.

I’d recommend you give it a try if you can be bothered. Or forget all of this and just be happy with what you have, which is no doubt fabulous anyway.

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.

 

[Heinrich]

I do not know the area that you live in but in my area of the USA …

Here in Europe the fluorescent lamp type was used in the bathroom, or in the basement maybe. Today I pickup RMI from computers with my bass guitar a lot—even my toothbrush runs on Linux. So, there might be reason to go balanced. On the other hand, w/ my Thorens the motor radiates hum, the single line interconnect, 3 feet long, doesn‘t catch buzz. The hum is not perceivable at any human volume setting.

What I somehow needed to convey is my perspective regarding the measurement plan. It failed, no prob/.

 

[mzxa]

High frequency can be dependent on impedance but what is there is low frequency and typical signature of some high pass filters. The designer is on the forum and I am hoping can address this more.

There is no high-pass filter in the amplifier chain, as it is completely DC-coupled from input to output. Instead of an AC coupling capacitor between the stages, a DC servo is fed back directly from the output, which results in a maximum of a few millivolts of DC error at the output. In practice, the EQ of the last stage interacts with the DC servo circuit, and the problem lies between the 20Hz breakpoint recommended by the IEC for the DC servo and the 50Hz breakpoint of the EQ. I considered moving the DC servo feedback point one stage earlier, which would have solved the "peaking" issue, but would have left a larger DC error at the output, which I wanted to avoid. I neglected this peaking; it was a mistake. Finally, after some brainstorming, I found a simple solution by adding a few passive components; the low-frequency transmission can now be restored without compromise.

 

[milosz]

Not cheap either... thanks for the testing on this.

A closer look;

View attachment 486084


JSmith

Hybrid Pewer Supply, eh? Laser guns? - pew pew pew!!!

 

[RigorDude]

Would it be ridiculous for me to think that the designer has no idea that he is manufacturing a strictly MC phono preamp?
High gain MC - 52db and 1k input
Low gain MC - 62db and 100r input
Very low gain MC - 72db and 100r input
Typical specs for a MM cartridge of 47k input and 40db gain do not exist for this preamp. Something weird is going on.
Otherwise flawless performance and only somewhat overpriced for a $100 parts count product.

I think you are spot on. The 52db gain level is the least likely use case. Audio Research used it a lot though, so it’s not without precedent. The only MM cartridges that would work this unit are the low-output (~1.5mV) Grado and Soundsmiths.
@amirm should have tested it at the higher gain levels. Hasn’t he done that for other phono stages? In this case, it does sadly seem as though an excellent piece of audio design is getting something of a raw deal on ASR.