Measurements and conclusion
Contents
Of course, we also took some measurements of the Grimm MU2. Now these measurements are not quite complete because we haven’t done a jitter measurement yet. There is a measurement point in the Grimm MU2, but our R&S probe turned out not to be good enough. We hope to add the jitter measurements soon.
Noise measurements Grimm MU2
We measured both the noise from the Ethernet port and from the power supply. The Ethernet port is nice and clean. No crazy stuff there. The switching power supply is certainly not dirty with a noise floor of around -110 dBu, but we do see some noise in the low-frequency section. These cause peaks at 55 KHz (-79 dBu) and 110 KHz (-104 dBu). It certainly does not leak through to the analog outputs, otherwise we would certainly have seen it reflected there.
Linearity and noise Grimm MU2
D/A converter
We already had an inkling that this Grimm MU2 would score well. We see a nice linear behavior and neat noise and distortion values. The linearity measurement shows that from -130dB the MU2 picks up. The Prism doesn’t get very much lower either, so it may well be that the MU2 can go deeper, but we simply can’t measure it with our Prism dScope.
The frequency response is dead straight up to 40 kHz after which we see some rolloff. At 60 kHz we see -1.3 dB approximately.
Looking at dynamic range, we see 108 dB approximately (107.7). This is – we estimate – mainly due to the increase in noise from 200 Hz to 10 Hz. Separate grounding to the Prism did not affect this measurement. This increase – if measured correctly – affects the dynamic range, we estimate.
Note: Grimm has revealed that the output has no capacitor and that they accept a small dc offset. This also explains that in other measurements with more averaging, this rise is gone.
In the noise & interference test we see – because it averages – that the noise there also increases a bit towards the low end: from almost -140dB to -130dB, which are really neat values by the way. Especially considering that the Grimm MU2 also has computers build in! These high-frequency components, also emit noise. The fact that we don’t see these anywhere is impressive.
In another noise test, we see similar values to the noise / interference test. A noise floor of about -140dB and at 10Hz about -130dB. So those do seem to be correct values.
If we then look at distortion measurements, we see only neat values. Both measurements on amplitude (loudness) and frequency are good. In short: Grimm has done his homework.
Pre-amp
Looking next at the analog pre-amp, we are primarily interested in the response and phase. After all, we have already measured the noise floor through the digital tests. It hovers around -130dB in our measurements.
The channel separation is around 108 dB when we enter analog and leave analog. These are decent values. Many power amps don’t reach those values. So no weak link here!
Response and phase is also fine: we see less than 1dB rolloff at 70 KHz. That indicates a lot of bandwidth within this MU2. Phase is 8 degrees at 20 KHz. So that’s also under control. We didn’t expect anything else.
Jaap — The “Notify me of new posts by email” has never notified me.
I wonder what effect your almost entirely not evaluating the better tube gear is affecting your view of what’s possible. It’s the question I asked myself after many years with a PS Audio Directstream I dac.
That is odd. It should work, although it only works for news for some reason. Check your spam. Maybe its there.
I can check tube gear. It is not that i am avoiding it :-).
Thanks, that’s helpful. Should I take it you don’t deal much with tube gear? I’m under the impression that LampizatOr being Polish is ubiquitous at shows in Europe, invariably with top end systems, and has a good following there. VAC being American (Florida), I’m not sure about, although in the U.S. their amps/preamps often show with Lampi and Von Schweikert speakers.
Hello Gene. We don’t review or compare tube equipment a lot. We’ve done some comparisons or used equipment with a tube in the past, but it is not our field of knowledge.
I do know that, although tube is being associated with ‘warm sounding’, it varies a lot too, depending on the design.
But although Grimm is very open sounding, natural and agile, in character it would probably not fit what most lovers of tube based components are looking for.
It’s funny, Hans Beekhuyzen characterized the MU1 as warm and in his comments said the MU2 is the same.
I would say it sounds very fluid and natural. Easy going… But not warm.
Thanks. Btw, your notification system doesn’t work.
Hey Gene! What notification system are you referring to?
I had a grimm mu1 on test, it wasn’t a bad device, but I personally don’t like what’s inside the box and the mu2 didn’t convince me either, no linear power supply, too small a box and too few parts which in my opinion are not worth 18000eur, MU1 played clean, detailed but to me it was a bit sterile and clinical and also thin with less space. For a similar price, I finally bought the playbackdesigns MPD8, which seems to me more musical, fatter and at the same time very detailed, but I would definitely like to listen to the MU2 as well
The number of parts is definitely not a criterium in my book. I will never understand people judging equipment like that. Just use your ears, as far as I am concerned.
not quite, why should I pay 18k for cheap accessories, for example? just because of the brand? I agree that parts are not everything, but there are manufacturers who worship a lot for nothing
I’m not saying it’s a case of grimm, I heard mu1 and my ears said, for example, this is not the sound you want
There is a sound for everyone. If we all like the same, it would be boring, right?
Yes of course 😉
Maybe it was not the sound that you needed. It’s always the combination of a whole lot of parameters from which the Grimm takes a few. It could be a mismatch with your setup no matter the quality level. The most important thing is to level the equipment and the room to a certain level. Find a good balance and from there it’s a matter of tuning. In the end it’s always difficult to point out which device is most natural and which is less. This is where reviews kick in. I think the ultimate sound should be for everyone’s taste.
True
Hi, I know Bruno Putzeys has worked together with the people at Grimm and I think as designers they are a little bit of the same school. In Bruno’s Mola Mola Tambaqui DAC he has also some novel ways of doing D/A conversion. It would be interesting to hear if there are similarities in the sound of the Grimm MU2 D/A converter compared to Mola Mola Tambaqui.
It sounds like the Grimm MU2 D/A converter is really special. If it’s that good it would be of interest to see a pure consumer D/A for all of us that don’t stream. It sounds like Grimm are already doing D/A converters for professional use. Best regards.
I have heard the Tambaqui a few times, but I am not very familiar with it. I have heard a lot of different DA converters though, and I cannot recall any other DA converter that doesn’t sound so unlike a DA converter as the MU2. So that rules out the Tambaqui as well.
It is very hard to put down in words. No, it isn’t like vinyl. No, it doesn’t sound ‘more analogue’. It is not HiFi anymore. It is ‘just music’.
Informative review. Before I upgraded from ATC SCM 40A to the 50 ASLT (and subs), I questioned others online about the Grimm active speaker(s). In particular, I asked if it had at least a touch of warmth, which I find need of for musical enjoyment vs. hardware listening. Without exception, Grimm owners steered me away. In light of that, I’m wondering where the MU2 fits in. I currently use a Lampi Golden Gate 3 dac, VAC Master preamp and modified digital only Oppo as a primary source for CDs and files from an SSD (USB). Streaming is in the future. Thanks,
Hi Gene, if you are looking for warm(ish) sound, the MU2 is not for you. The MU2 is very natural and neutral. I don’t know the equipment you are listing, so I have no auditory reference.