Pro-Ject Phono Box DC MM/MC Phono Preamp Review

[JeremyFife]

Although 'headamp' makes me think of guitar pre-amps ... different use

 

[welwynnick]

Although 'headamp' makes me think of guitar pre-amps ... different use

Yeah - or it could mean microphone head amps. It's a bit ambiguous, it depends on the context - live, recording or replay.

 

[somebodyelse]

Is the term "headamp" synonymous with phono pre amp?

Possibly. It depends who you're talking to, possibly based on country, age or areas of experience, so you'll probably have to work it out from context. I've heard it used as a generic term for the first amp stage in the signal chain of an instrumentation system, possibly responsible for signal conditioning for the transducer. That fits the audio usage for a stand-alone phono stage, an active MC to MM step-up stage, or a mic preamp. I've not encountered separate amps for tape heads, but it would fit that too. The other main audio usage is for a headphone amp. I don't know if the guitar amp head comes from the same root.

 

[ryanmh1]

This looks okay for the price, but when it comes down to it, if you look just at noise, this is barely competent. It does not do as well as multiple other offerings for the same or similar price, many of which have loading options and filters. One would think Pro-Ject, which is a turntable company, could and would do a little better than what amounts to a ($175) phono dongle from Emotiva. Aiyima posted measurements of their $99 T3 Pro which (if they hold up) were much quieter that the Pro-Ject, plus it offers a lot more flexibility for $100. Really curious how the MC is in that Aiyima. Even the built-in stage in the Marantz pre/pro is quieter, and there's some reason to think that might be in every Denon/Marantz AVR since they spec the phono stage identically in every AVR at least from the X3500H on up, and have no particular discussion of any special phono stage in AV10 despite it being a premium product...

 

[Kimbrough Xu]

I was totally impressed by the implementation of RIAA equalization:
View attachment 387285
It is rare that we see such flat response regardless of price! Would have been nice to have a high pass filter though to deal with LP rumble and other low frequency noise but that would have increased the cost.

Hi, Amir, thank you for your great review, but with my knowledge, I can not understand why do you say a HPF is nice feature for this phono stage? Do you mean you dont want the signals under 20Hz?

 

[nathan]

Hi, Amir, thank you for your great review, but with my knowledge, I can not understand why do you say a HPF is nice feature for this phono stage? Do you mean you dont want the signals under 20Hz?

LPs don’t have much if any real content there other than the mechanical noise of the gear and the groove Think of it as a rumble filter.

 

[AudioSceptic]

Hi, Amir, thank you for your great review, but with my knowledge, I can not understand why do you say a HPF is nice feature for this phono stage? Do you mean you dont want the signals under 20Hz?

You might find the conversation starting here <https://www.audiosciencereview.com/...o-mc-pro-phonostage-review.47139/post-1685555> of great interest.

 

[NTTY]

20mV input at 15kHz causes clip, that is ridiculously low!
A cartridge output is mainly at higher frequencies, and that's where the headamp needs the headroom.
Michael Fidler Spartan 5 (£150) quote 420mV @ 10kHz as opposed to about 27mV that this device can take.
Headroom is vital is headamps.

Hi, it might be because the view includes noise in the calculation (?), but it does not clip at 20mV input at 15kHz. A friend of mine asked me to review his Phono Box and I found that noise floor is elevated relative to the low voltage input at high frequencies, and that causes the THD+N to go above -60dB.
Fact is because of the RIAA curve, if non compensated by the Software performing the measurement, it will compute high level of noise at low level input. The Box is noisier at 15kHz compared to 1kHz. Let me try to show that. The below is 20mV input into the box at 15kHz:

That descending noise view is the RIAA curve that compensate for the one of the vinyl. And if we compensate it in the software, as it happens IRL, then we get:

It is the same measurement, but and you can see that the former one had a THD+N of -52dB and the later shows -62dB of THD+N. The second view is the realistic one because it would be the reproduction of a 15kHz as it was recorded on the vinyl.

So, I did a THD vs level sweep and only included THD (5 harmonics) in the below view:

You can see at what levels the Box truly clips. At 15kHz, it is around 155mV input.

That said, it does not explain the -20dB THD+N that Amir measured for 50mV input at 15kHz. On my side I see -66dB, entirely dominated by the distortion:

Cheers