The Major DAC
Contents
For many, the heart of the Grimm MU2 will be the d/a converter. Although we must say: the preamplifier is also terribly good…. It is so good that we dare to say that you don’t need a preamp with the MU2.
But back to the d/a converter for a moment. Grimm wouldn’t be Grimm if they took a different approach. Under the hood there is no NOS dac, no standard AKM or ESS…. there’s a “1.5” bit dac inside. This one the gentlemen in Eindhoven have dubbed the “Major DAC.
This ‘Major DAC‘ is a kind of modified version of DSD, since it works with not two but three ‘levels’. There is a 0, a 1 and a kind of 1.5.
0 is 0 100% of the time. A 1 is 50% of the time 0 and 50% of the time 1. And the “1,5” is 100% of the time 1. So it is a very basic PWM (pulse width modulation) construction. The reason Grimm chose this form of conversion is to get rid of the modulation problems of 1-bit DSD. But let’s take a small step back.
The development of this ‘1.5-bit dac’ was done by Pieter Meijer and Gertjan Groothulze. It was not easy to develop. It took about three years. The reason Grimm did not go for multibit is that it is practically impossible to get a fully linear character. Getting above 18-bit resolution is very difficult.
Bitstream – DSD – again has the disadvantage that the high spectrum is not fully linear with signal strength. Moreover, stable clocking is particularly important with DSD: the frequencies are very high. As is keeping the high-frequency output in check. This noise can be a burden on amplifiers and speakers.
Now there is an intermediate form: dacs that work internally with a 5bit architecture. However, this also requires a very high (sometimes even higher) internal frequency than DSD and we have to deal with very complex noise shaping, which in turn requires more processing. This costs money, which often results in sub-optimal performance: exceptions aside.
So, the Grimm-solution is in the 1.5-bit design. This PWM technique is kind of a hybrid of DSD and the 5-bit dacs.
The 1.5-bit design still has to deal with an incredibly high noise floor (you go down from, say, 24 or 16 bits to “1.5,” which increases the noise floor by about 6dB per bit). Therefore, extreme filtering must still be done to get rid of the noise.
Grimm uses an 11th order noise shaper. That’s insanely steep. And – we estimate – it also requires a lot of processing power as a result,. However, that can be done just fine with the powerful FPGA in the MU2. Moreover, the noise shaper – according to Grimm – works completely error-free and completely linear.
The FPGA with noise shaper and oversampling then sends the signal into the converter. Grimm opted for an FIR-DAC. This consists of 16 dac cells per side. This then sends the analog signal into the pre-amp where the volume can also be regulated.
(An “FIR DAC” in this case refers to a DAC that integrates a Finite Impulse Response (FIR) filter. The FIR filter is often used to shape a digital signal before it is converted to an analog signal. This integration is beneficial in applications where precise control of frequency response is important. And so this is certainly the case with the MU2)
The whole thing is clocked with Grimm clocks. Obviously the best they have in-house. Each clock – we know – is measured separately before they go on the PCBs. So it is really hand selected.
Too good to be true… right?
This story may sound like too good to be true. That’s kind of how we thought of it, too. After all: the audio world has been digitizing audio for more than 40 years. If this is the egg of Columbus, it must have already been found by a major company, right?
The fact is: large companies are more often concerned with margin. Not (anymore) with innovation. Unless of course it makes a lot of money… but then we are indirectly talking about margin again.
Technologies like the Major DAC no longer make enough money for large companies…. it’s as simple as that. And so it is that a – relatively – small company like Grimm can come up with such a design. Pretty cool, right?
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.