Mofi StudioPhono Stage Review

[morillon]

Good job from Amir as always.
It's a shame that this device has such poor ergonomics. Obviously, the brand wanted to save money to the point of making the setting changes perilous. This compromises the use of the device with an MC cell. The brand is expected to review the design of the device on this point, even if it means increasing the price a little. The other weak point is the RIAA EQ which should be better.
The brand should use the results of this test to improve its product, which is in fact unfinished. Still, it has some interesting qualities: an efficient subsonic filter, frequency-independent leeway (which is rarely the case), and good distortion management.

the too vague respect for the riaa curve agree... but the ergonomics of the adjustments are to be put into perspective I think... and are not supposed to come back to it constantly...*
(the toothpick will do it very well ;-) )
;-)

*(unless you really play with many cartridges or tonearms etc... well in this case you will probably use a much more ambitious phono stage, right? with sut or prepreamp etc)

 

[Hipster Doofus]

Nice …get right back on the horse with another review and let’s all forget about those companies that don’t like comments. For awhile at least.

 

[Ron Texas]

I remember when all preamps had a phono stage built in.

 

[DanTheMan]

I really wanted this one to perform better as I have an affinity for the brand and the look. It definitely has some pluses but the RIAA is just too bright for me. I have a Pro-ject and a Schiit which are both nice, but price to performance, it is tough to beat that Schiit.

 

[DualTriode]

You're missing the point.

I made the point and you missed it.

The noise is very real and and very quantifiable.

You did not read the Audio Precision link that I posted, did you?

 

[AudioSceptic]

Indeed they are... I should get my eyes checked, that is just a sticker in your picture I see now, I thought there were more.


JSmith

I wonder, did the sticker describing the dip-switch settings fall off, or wasn't it there in the first place, requiring the owner to RTFM?

 

[DSJR]

I really wanted this one to perform better as I have an affinity for the brand and the look. It definitely has some pluses but the RIAA is just too bright for me. I have a Pro-ject and a Schiit which are both nice, but price to performance, it is tough to beat that Schiit.

If you use dull cartridges such as Rega's home made examples (the cheap carbon is a 'poshed up' AT91), mid priced Sumiko or many modern Grado's, this MoFi box will help eq them just fine. Ortofon OM's seem to have an otherwise benign gentle rise over 10kHz and mid level AT's have a rise at around 10 - 12kHz or so. This box isn't severely out by 'analogue' standards, but a slight roll-off at hf I'd suggest would be preferred as so many modern MM types actually rise at hf now rather than fall, as old fashioned MM's used to before the pole piece advances that makers began to introduce, which encouraged a much flatter playback response I remember.

The Mani 2 is pretty darned all you need in the US and we here have the Spartan 15 which I'm trusting maker @Michael Fidler does as good a job on (as far as costs allow) as he does the more advanced models. MoFi do turntables too and over here, they're rather expensive, may I say...

 

[Ken Tajalli]

Thanx for the review.
I wonder, are there any battery powered (or not) balanced input headamps, that can be installed inside or very close proximity of a turntable?
Something that would take balanced input from cartridge wires, assuming one has not been grounded by tonearm.

 

[MusicNBeer]

I shared my unit's measured performance in 2020. I got pretty much the same results. I got a Duo and the Mofi has been in the closet since.

Mofi StudioPhono phono preamp homebrew measurements

Wasted my vacation day today doing some MM measurements on my Mofi StudioPhono phono preamp. My equipment: Hardware: - Soundcard is a lowly ASUS Xonar DSX 7.1, but it actually has decent ADC performance when run at 44.1 KHz. ADC input used for signal analysis. ADC saturates at 1.025 Vrms...

www.audiosciencereview.com

 

[Toni Mas]

Mono switch is a very nice feature that all phono stages should have. Mono playing hugely reduces surface noise of old vinyls. Rock solid center image as added bonus...

 

[Mikig]

As they say "without praise and without infamy".

It seems to me to be a mid-range product, with average performance.
The appearance is nice, but the plastic case seems a little subdued to me.
We are now used to seeing metal boxes even on devices costing less than 100 euros.
The mono switch is good.
Probably, for the cost of this phono preamp or a little more, you can find something better performing and more definitive on a new or even used one.

Thanks Amirm as always for the review!

 

[restorer-john]

I made the point and you missed it.

The noise is very real and and very quantifiable.

You did not read the Audio Precision link that I posted, did you?

Amir doesn't display the residual noise as a figure across the measurement bandwidth. His choice. We had that discussion/argument years ago- went nowhere. Maybe you weren't here. I dunno. You didn't do a search did you?

If there's no distortion, we can work residual it back from the SINAD. If there's distortion of significance, you cannot. If he supplies a S/N number (a proper one) ,we can.

I measure what I want and you measure what you want. Amir does the same.

 

[staticV3]

Basically with 40dB gain, 47kΩ Zi, 22.4kHz BW, while outputting a signal, the StudioPhono adds ~120μVrms of Z-wt noise to the output (.58*10^(-73.6/20))


In comparison, a modern $80 DAC (SU-1) has about 35dB less inherent noise, resulting in roughly 10% as much audible hiss.

If we were to apply A-wt, then I think the difference would shrink as the StudioPhono's PN-ish noise signature would be more affected.

 

[restorer-john]

Basically with 40dB gain, 47kΩ Zi, 22.4kHz BW, while outputting a signal, the StudioPhono adds ~120μVrms of Z-wt noise to the output (.58*10^(-73.6/20))
View attachment 365159

In comparison, a modern $80 DAC (SU-1) has about 35dB less inherent noise, resulting in roughly 10% as much audible hiss.

If we were to apply A-wt, then I think the difference would shrink as the StudioPhono's PN-ish noise signature would be more affected.

No.

You cannot determine residual noise this way. Noise in the presence of signal is not residual noise. Nor is it how phono stages are measured for residual noise. Never have been.

You short the inputs (no signal) and measure the residual. For all we know, the dominant noise (mains related) could be the AP's connections to the phono stage, earthing etc. Or it may be in the stage itself. You cannot assume until you disconnect and short the input stage.

 

[amirm]

It is hard telling what the noise floor level is or try to determine what level the noise will be if you put your ear in the speaker.

I have indicated the FFT bins at 32K. Using simple math, you arrive at 42 dB of FFT gain (the effect of window is very small). So just add this to the noise floor in the dashboard FFT and you have your actual noise spectrum.

 

[TonyJZX]

Conclusions
You already know my feeling about the packaging so I won't belabor that point. Technically, performance is about average with RIAA equalization being a bit worse than average. A bit more focus on accuracy would have lifted the unit up a notch in my opinion.

As it is, I can't recommend the Mofo PhonoStudio. <my emphasis>

-----------
As always, questions, comments, recommendations, etc. are welcome.

Well I've never seen such vulgarity in my life.

I'm sure its just a result of dealing with those 'Mofo' dipswitches I guess...

 

[Mikig]

In confronto, un moderno DAC da 80 dollari (SU-1) ha circa 35dB in meno di rumore intrinseco, con conseguente circa il 10% di sibilo udibile.

Can I ask a perhaps trivial question?

I'm not a technician, but I always notice that normal amplifiers and DACs have much higher performing circuits with a much better SINAD and lower noise than the average prephono. what I don't understand is whether it is a circuit problem with all the phono preamps or a problem with the source which is analogue?
As you rightly say, an $80 DAC performs much better than even the best phono preamp tested.

 

[TonyJZX]

thats the nature of the beast right?

vinyl just doesnt have the dynamic range of redbook?

 

[staticV3]

No.

You cannot determine residual noise this way. Noise in the presence of signal is not residual noise. Nor is it how phono stages are measured for residual noise. Never have been.

You short the inputs (no signal) and measure the residual. For all we know, the dominant noise (mains related) could be the AP's connections to the phono stage, earthing etc. Or it may be in the stage itself. You cannot assume until you disconnect and short the input stage.

Sure, but shorting the inputs is a synthetic test which is hardly relevant to the average consumer who wants to plug something into the inputs.

As such, we can use Amir's measurements during actual use as a plausible best case scenario:
How much noise is there on the DUT's output with a reference-grade tone gen, connected to other mains-powered equipment, but with extensive care put into GNDing?

A: ~120μVrms (Z-wt)

 

[staticV3]

I'm not a technician, but I always notice that normal amplifiers and DACs have much higher performing circuits with a much better SINAD and lower noise than the average prephono. what I don't understand is whether it is a circuit problem with all the phono preamps or a problem with the source which is analogue?

I'd say both. Vinyl records and players output a suboptimal signal, which in turn requires tricky preamplification to become usable.