Grace M101 Microphone Preamp Review

[amirm]

This is a review and detailed measurements of the Grace Design M101 single channel microphone preamp. It is on kind loan from a member and costs US $833.

OK, this is not a design that I would fall in love with but in the context of studio gear, it will get a pass.

I really like the gain setting knob. On the left, you set it in coarse steps but then can fine tune (positively) with the right knob. Works well.

Ribbon button per documentation gives you a DC path with no phantom power. HPF does what it says (see measurements below).

Back side is simple:

For testing, I used XLR out and input.

I have not done too many mic preamp measurements. I noticed company had very detailed specs so I decided to replicate them.

Grace Design M101 Microphone Preamp Measurements
Company spec standardizes on 20 dBu output at three different gain settings. I followed suit:

Across all three gain settings, actual results beat the company spec. Distortion is vanishingly low as well. Nice!

Company provides a single IMD spec but I decided to run a full sweep:

Again, we beat company spec and this time, by fair bit. Nice again!

With respect to frequency response, I am seeing more attenuation in ultrasonic than company states:

It doesn't matter in practice but there it is.

I imagine the most important bit is Equivalent Input Noise (EIN). I set the amp to 60 dB gain and ran the "recorder" output averaged at three source impedances:

I more or less grabbed the peak value. Using those, we see that we essentially match company spec.

Conclusions
I don't think I have seen this level of honesty and excellent performance from a company. The M101 delivers same or better performance in all of their specs. Price is up there but as is attention to circuit design hygiene.

I am happy to recommend the Grace Design M101 microphone preamp.
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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

 

[amirm]

 

[phoenixsong]

I wonder what the use case of such a device would be in today's market

 

[Videoteque73]

I wonder what the use case of such a device would be in today's market

To have a very good preamp in a studio with a medium mixing board. Normal mixing boards can’t have great preamps or they would cost too much.

 

[daniboun]

Tear down
See attached file

 

[TheWalkman]

This device is nowhere near my current wheelhouse although I’m proud to say I did have some mixing board experience on my high school AV crew.

With that in mind, this seems to be very expensive for what it does.

 

[Miley_B]

Thanks for the review and member who sent it in.
Looks great, although for a single channel it might be considered somewhat pricey. I personally know at least one studio that has this pre in regular use.
Interestingly It’s far from a new design, it was released in 2008 and is a development of the Model 101 released in 2001.
The inclusion of the ‘Ribbon mode” is interesting. They state it bypasses the input decoupling capacitors and raises the input impedance from 8.1kΩ to 20kΩ.
Maximum of 75dB of gain when the trim pot is at +10 is a healthy amount.

This is their August 2008 newsletter that they still have available online with the release info if anyone is interested. https://www.gracedesign.com/newsletter/august08/newsletter08_08.htm

The company is clearly prepared to stand behind their product, the 20 year warranty is impressive!

Finally, additional context would be helpful to judge where it sits in the clean mic pre market, I can only find tests of interfaces such as the Focusrite Scarlett and the ADC has generally been tested with a much stronger signal than you might get with a microphone, have any comparable microphone preamps been reviewed on ASR?

 

[RexrothPigeon]

LPF does what it says (see measurements below)

Think this is a typo (the faceplate says HPF)

 

[TNT]

I wonder what the use case of such a device would be in today's market

Hook a mic to it and in turn a really good ADC and play some Bach on a cello in a nice room.

This is how babies are done ;-)

//

 

[andymcbain]

Nice to see this being reviewed and even better to see that it measures up. I would read about Grace products in the likes of Sound on Sound back in the day and try and justify the cost… still can’t. A serious mic pre for those who demand a clean signal

 

[Sokel]

Measurements aside (really good), what I do know about Grace designs is that they work, no matter what, to the point it becomes boring after some decades (no drama, for good or bad for a tinkerer )

Thanks Amir!

 

[peniku8]

I wonder what the use case of such a device would be in today's market

Was asking myself the same question. In any setup, be it a large recording studio, small home studio or mobile recording, you'll be using an audio interface (unless you're *really* mobile and use a fully integrated recorder) with integrated mic preamps.
And if you have the money to buy a near 1K standalone single channel mic pre, you can also buy a top of the line audio interface and have no need for an external, non remote controlled single channel mic pre. Would be interesting to see how a top tier audio interface mic pre compares against this one in terms of noise floor. The 300 Ohm output impedance is a lil rough tho. That won't pair too well with the Cosmos ADC, which would otherwise be the obvious choice to digitize whats coming out of a high SNR mic pre.

 

[AndreaT]

I wonder what the use case of such a device would be in today's market

Voice over recordings in a home studio.

 

[JayGilb]

Tear down
See attached file

Good design. Shielded power supply. Isolated sections and smart component layout.

 

[yo!]

This is a real 'pro' preamp, overdone in every hinsight and therefor spot on.

 

[Steve Dallas]

I wonder what the use case of such a device would be in today's market

A lot of project studios want 1 or 2 'drive anything' mic pres to augment what is built into interfaces / consoles. I have owned one of these for 20+ years.

 

[abe_zydar]

Thanks for the review @amirm. Great to see another company, which includes RME, that stands behind their specs.

 

[GWolfman]

A new brand for me! Considering the praise so far and the test results from @amirm, I’ll definitely check them out.

Thanks!

 

[SSS]

Great data and seems to be a sound design. Price is for Pro usage, in Germany relatively expensive. What I would like to see is a display of the db adjustment setting and a lower output impedance in the region of 50 Ohm. But I do not record. So the Pro's need to check the unit for specific microphones and A/D units.

 

[skankhobag]

I own the previous version of this that doesn’t have the ribbon mic option. It’s a startlingly clean preamp.

The use case is pretty simple: you want a distortion-free gain path to your ADC with no compromises. We’re talking about recording individual vocals & acoustic instruments using a variety of microphones.

Here’s where this fits:

• Audio interfaces that have one or two mic preamps are usually “prosumer” grade: fine for podcasts & simple demos, but not good enough for studio grade recording

• Audio interfaces that are professional grade have too many mic preamps. Personally, I have no need for 8 mic preamps. I do, though, need one really, really good one. Haven’t seen any bench tests of $2-4k interfaces (their specs look great), but there has to be some place where they lack just a hair in performance with 8 or more mic inputs.

• In both cases, you have long cable runs from the microphone to the mic preamp/ADC since the interface is close to the computer. Again, running under the assumption you’re attempting serious recording, not a podcast in your garage.

The cable runs between transducers and their electronics should be as short as possible. Since microphones and loudspeakers are both transducers, it applies equally. Once you’ve gotten the reactive, low-level mic signal turned into a high-output line signal, go ahead, have your 30ft cable run to the ADC.

I use a Mogami Platinum Studio 3m cable from mic to pre. It’s the beefiest mic cable I’ve ever seen (18 gauge wire - $100).

It wasn’t tested, but the high impedance input is fantastic for electric guitars. I astonished a friend when I brought his Parker Fly straight in through pre/ADC and ran that clean signal through 3 different virtual amps (Marshall, Soldano half stacks and a Fender Twin) cranked in 3 different virtual rooms with a ton of effects. His mind was BLOWED! Permanently.

Another small consideration is that, psychologically, the artist feels part of the engineering process when they have the mic preamp and ADC with its meters right in front of them. I have mine in a rack case on a guitar amp stand angled upward toward them.