A humble request for education on phono pre-amps

Some years ago I fell into the rabbit hole of headphone pre-amps for my digital setup. After a ton of research, asking around, auditioning and hand-wringing, I came away with the general conviction that any solid-state headphone amp with sufficient power to drive your cans at the desired volume with a little headroom, low enough noise, and build quality/QC (which is no small thing, these are important!) is going to be more or less, for my purposes, the same - outside of that you might be paying for extra features, design differences, compatibility, etc. (And then of course there are tube amps, which obviously bring a lot more differences to the table, but I didn't go that route.) I'm sure there are a ton of people that disagree, and those disagreements have merit, but for my cans and my ears and my use case, it wasn't something I noticed experientially - especially with my digital music, which was of varying quality to begin with.

Anyway, now I'm looking at upgrading my vinyl setup, and I'm running into the same quandary. I approached my initial pre-amp purchase with those assumptions in mind - I wasn't ready to get into tubes at this point, so I looked for a solid state that fit my needs and landed on the MoFi Ultraphono. Headphone jack, subsonic filter, mono button, MC cart compatibility - ticked all the boxes. And it's fine! (I'm running a Nagaoka MP-110 on a Rega P1.) I do notice that the headphone amp feels a little claustrophobic at higher volumes, but without buying a much higher end pre-amp and dedicated headphone amp, I'm not sure how I would be able to check whether that wasn't just a characteristic of my table/cart.

But now that I'm looking at a higher end turntable, I'm wondering at what point this pre-amp will become a bottleneck. If this were digital music and this were a comparable headphone amp, I would assume the answer would be, for my ears, "essentially never." But I suspect that with vinyl things are different - I think the job of most digital/solid state components should be to "get out of the way," but the basic function of a phono pre-amp adding RIAA EQ is inherently a huge finger in the pie, so I suspect there's more to it in this case.

The issue I keep running into is that of all the major components of a vinyl setup, the pre-amp seems to be most susceptible to the kind of buzzy, subjective terminology that drives all of us nuts about this hobby. Speakers, TTs, and cartridges all have obvious and measurable differences between brands, design, components and features. I can totally understand how and why a cartridge can have lower crosstalk than another, a tonearm can track better than another, or speakers can have better clarity than others. But a pre-amp adding "musicality" or having "authority," that's when my eye starts twitching.

So my very ignorant questions are - how important/variable is a SS pre-amp in a vinyl setup anyway? How much does the RIAA curve change from one pre-amp to another? Besides QC, quietness, lack of distortion and compatibility, what does a good pre-amp offer that a table, cart and speakers aren't doing most of the heavy lifting for already? Should I be auditioning a bunch of pre-amps as I look into upgrading my setup?

Thank you for your experience and input!!

 

For a phono pre you want sufficient low noise gain. Depending on what kind of cartridge choices you may be making in the future, you may want adjustable gain. You want the input capacitance to be sufficiently low and/or adjustable, and again depending on the range of cartridges you might want to use, you might want the input resistance load to be adjustable -- remember a phono cartridge is a passive generator so its inductance will combine with the resistance and capacitance of the phono pre load and phono cable to shape the frequency response of the cartridge, and the effects will be particularly pronounced with MM carts because of their higher inductance relative to MCs. Obviously you want accurate RIAA equalization. You may want features like a subsonic filter and/or mono switch, or not. To minimize the intrusion of ticks and pops and momentary surface noise you want a circuit and power supply that can deliver a high overload margin (which is not necessarily common in a lot of cheap after-market phono pres), and you may also want to try a no-feedback design.

 

Very helpful, thank you!

 

It looks like the Ultraphono has a decent selection of both gain, and loading settings. And decent specs. Of course no 2 phono stages sound identical.

I would say if and when you acquire another turntable, give the Mofi unit a whirl unless you have recently bought it, and have contemplated returning-exchanging it for something else?

With the new table acquisition, are you also planning a Cartridge upgrade as well?

You asked about differences between the countless phono stages. Two hurdles all phono stages commonly have to deal with, is their abilities to reject RFI-EMI. And this can occur with even expensive phonostages, as well as phono cabling being suspects to cause such.

 

Yeah, I did just buy it - I could probably exchange/return it if I had the perfect thing in mind, but with Covid it's hard to get out and listen to stuff. Not to mention that a lot of places I could audition equipment have gone out of business in the last two years (or like TTL, moved to online only).

I'll probably hold onto it for now and when I get the new table maybe it will be a better time to try a couple things and see how they sound with the new rig.

 

I edited my post since you replied, so, better explanations might help folks make suggestions, or there are others who perhaps have the Mofi Unit, and can comment further about it.

I know it's difficult to personally audition the many units that are out there today, and about all one can do to assist-help, is ask questions, read as many reviews as you can.

 

For sure planning to upgrade the cartridge! Depending on what I buy I may plan to get an everyday cart in the 500 range and if I get a table that's easy to swap carts with, maybe something higher end to play on the good stuff.

As for interference, my house's electric is a century old and still has some tube and knob wiring in the walls, so ground hum and EMI is probably never going away entirely while I'm here. But yes, good to keep an eye on. Also considering a power conditioner down the line.

 

Just stick with what you have for now. If you are mainly using high output cartridges, the unit you have will likely work well with most of them. If you want a different phono preamp, take your time and shop around. It helps if you know what cartridges you are going to use with it. Then try to audition them at home, in your system. Some online dealers have generous return policies to accommodate this. Sometimes manufacturers have programs for home audition, or generous returns when buying direct.

 

Phono preamps definitely have quantifiable characteristics that matter:
- Dynamic range (and its noisefloor)
- RIAA filter accuracy
- input overload margins (to prevent overloading from picking up static electricity)
- input capacitance (for MM cartridges)
- input resistance (for LOMC cartridges)
- its grounding scheme (floating signal ground vs signal ground connected to PE)
- amount of gain (IME, gain for MM cartridges tends to be on the high side with many modern preamps)

How these impact on your experience depends on use case of course.

 

Be patient, learn, between this and your TT thread I see your taking it in, learning new choices, researching. Keep doing that. If possible, spend up the first time, pick things with known good synergy from either others who have tried or from listening / auditioning yourself. But take your time, there are so many choices out there....

When I took all of my gear out of storage in 2015 after a long hiatus, I thought I could be happy with certain choices at that time as I upgraded, but this time found myself wanting more, and wish I could go back with what I know now. I'd have spent up the first time!

But sometimes there's no way around it if you're one who strives for the optimal / end game sound - you have to try things too. Hearing things in someone else's setup / room or relying on others good experiences can only take you so far, and it's rare to "get it right" the first time IMHO with an optimal vinyl setup. Your set up skills with vinyl are more important than the gear choices too, I can't stress that enough. If building a good vinyl system from scratch, you may find one or two things that didn't make it for you the first time - but then again you'll never know unless you compare (and many don't - the level of difficulty goes up exponentially if comparing components is part of the process). So many "buy this, it's best" recs are made from people that spent eons deciding on one piece, but never compared anything else at the same level. I seek out those that have tried many things.... especially those that aren't trying to sell you something.

And yes, with the level of TT's you're looking at, I'd plan a higher end phono preamp too. The phono pre is the critical piece that will determine your vinyl experience - that and the cartridge / set up skill too. Set up skill more than anything. Oh, a good linestage, amp and speakers too are assumed... one weak link and the whole house caves in. But don't buy a $4k TT and not give it a proper phono preamp....

 

Phono pre-amps handles the lowest signals in the chain, so it is of course important that this component in the change is of good quality.
Phono pre-amps do differs, it's about the quality of components used and the circuit layout.
Better components will allow more of the signal go through without degradation, noise and distorsion.
They do sound different.
This thing about musicality - it's like any amplifier really.
There are some amplifiers - and pre-amplifiers - that are better at following the rhythms of the recording and holding everything together than others. Some has more clarity than others. Some are more neutral sounding, others are brighter, others are warmer sounding etc.
The Mofi phono-products are quite neutral that leans on the bright side. One of the most detailed for the money and a good buy.
But I'm using a Pro-Ject Tube Box S2 with Pro-Ject Accu Box power supply/conditioner. This gives a character that I like with added texture and more contrast between the instruments in the mix. It's not neutral, but it's pleasing and friendly for the ear.
This is a 700 euro combination for my 1500 euro turntable. It works well.
My phono pre-amp combination is more expensive than my cartridge, I use a Benz MC Silver for 350 euro.
If, or rather when, I upgrade my cartridge I won't go above the cost of the pre-amp.
I have built my phono setup after this philosophy:
Spend the most on the turntable, then the phono pre-amp and then the cartridge.
I won't spend more than max 50% of the turntable cost on a cartridge. And not more than on the phono pre-amp.

For a 4 000 euro turntable I would look into up to 2 000 euro phono-pre's.
For me it would be probably like the EAT Petit E-Glo or the EAR Phono Box or Clearaudio Basic V2 or something from Icon Audio, or something else...

If the turntable comes with XLR out, then I would look into phono pre's with XLR input. Funnily enough, many phono pre's with XLR output doesn't have XLR inputs...
But Pro-Ject Phono Box RS2 has XLR inputs, there is also a model from Teac that has it.
And a few more.
XLR outputs from turntable are recommended with low output MC's.
If you plan on getting a MC, then a step-up transformer could be an interesting choice. But I don't know any with XLR inputs.

But each to his own budget and so on...

 

Little update here - I had a chance to audition a friend's Lehmann Black Cube Statement alongside my MoFi, and sure enough there was quite a difference, even to my dumb ears on my modest setup. The MoFi sounds good, but in comparing them I noticed it felt pushed and a bit claustrophobic compared to the Black Cube, which was much more airy and open, with lots of clarity. A little more high end as well, while the MoFi was a bit thumpier. It almost sounded like the MoFi was sending too much juice to my receiver, which is definitely a possibility - so it may just have been an issue with my setup and not an inherent fault of the MoFi.

My only gripe with the Black Cube is how obnoxious it is to have the input and output on opposite sides - I'm sure lots of setups work just fine that way, but in mine one set of cables is kinked hard to reach around to the other side. If I get my own I'll probably spring for one of the models with all the connections in the back.

Sidebar for Lehmann owners: do you find the relatively low number of cartridge settings cover most of the bases you need? And do you find that the "house sound" of Lehmann is consistent between models?

All of that is to say, I really got an appreciation for the difference between two not-super cheap pre-amps that are both pretty well reviewed. There's obviously a lot of room for finding what works with an individual setup and individual tastes.

Now I just wish it was easier these days to go audition a bunch of pre-amps to really check out the full range of options. Thanks for everyone's input!

 

It should be noted that Mofi phono pre has a limited input overload margin. This basically means that with cartridges from 5 mV output and above, there can be distorsion rise with some records that are high in volume. Even at the 40 dB setting. The reason for this is the quite inexpensive power supply.

With Mofis own cartridges (they have 3.5 mV output) there is no problem.

 

Yes! I had read about that and considered it, it's definitely what it sounded like. I'm running a Nagaoka MP-110 so there's a good chance it was running too hot. So maybe not an issue of the house sound exactly - but definitely a dealbreaker if I can't run a ubiquitous entry level cart on it (and I had it on the lowest gain settings). Agree, though - probably would have been much better with a cartridge that didn't make it go nutso.

 

Not sure if your comments are based on measurements or listening, but the HiFi News review of the UltraPhono with measurements by Paul Miller actually showed a pretty high overload margin, 24db ref to 5mV @ 1% distortion (82mV @ 40dB @ 1K). I have also seen this backed up by one of the members here with his own measurements. Maybe some of the units have a problem since I have seen a couple other members here echo what you say?

 

There are many entry level cartridges < 5 mV. Audio-Technica has a bunch of them, and the Mofi cartridges are based on Audio-Technica but in a Mofi designed and manufactured body. Also Sumiko has a bucket load of < 5 mV cartridges.

40 dB is considered an ideal match for 4.0 mV cartridges.