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Metrum r2r (Multibit) DACS

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#1
So this forum has had a lot of interesting things to say about Schiit DACs and their supposed mulitbit superiority.

One other contender in this area is Metrum. Their dacs are even more expensive than the Yggdrasil. They claim to be r2r (multibit) dacs and use other audiophile buzzwords like NOS (no oversampling).

https://metrumacoustics.com/product-category/digital-to-analog-conversion/

I'd really like to see how they measure up. Has anyone tried any of these products?
 

solderdude

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#2
Metrum 'believes' in filterless DACs. So do many 'followers' that only use their ears.
It's not as big as a problem to use them as long as you use a lot of upsampling (would recommend to at least 176.4kHz).
In that case the 'stairsteps' are smaller and too high in frequency to cause problems (well maybe in some amps).
The speakers/headphones will act as low pass filters.

Myself I would prefer a well implemented DAC.
DS works fine for me but well implemented oversampling R2R is also good enough for me.

NOS R2R designs without proper reconstruction filters ... I would steer clear of this myself.
But others don't have to.
 

Veri

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#3
Metrum 'believes' in filterless DACs. So do many 'followers' that only use their ears.
It's not as big as a problem to use them as long as you use a lot of upsampling (would recommend to at least 176.4kHz).
In that case the 'stairsteps' are smaller and too high in frequency to cause problems (well maybe in some amps).
The speakers/headphones will act as low pass filters.

Myself I would prefer a well implemented DAC.
DS works fine for me but well implemented oversampling R2R is also good enough for me.

NOS R2R designs without proper reconstruction filters ... I would steer clear of this myself.
But others don't have to.
The Massdrop Airist R2R upsamples to 192 Khz with a NOS-like high-frequency roll-off to cater to both camps :D

Hits a wonderful 10.5-bit ENOB/linearity. Wonder how audible something that "bad" is lol
 

gvl

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#4
The person behind Metrum designs seems to be an engineering type, I've watched a couple of interviews with him and there isn't a lack of measurement gear in the shop and he isn't shy to use it. I believe they use a gentle analog low-pass filter on the DAC output from 50kHz up so external oversampling should go well with Metrum DACs, at least in theory. I would very much like to find out more about the performance of their DAC modules especially at higher sampling rates. They claim close to 24 bit linearity and -155dB noise floor in their TOTL products, kind of sounds too good to be true...
 

solderdude

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#5


The scope shot above is of a 10kHz signal scopeshot from a Metrum Quad DAC (the smaller brother of the octave)
It is intended to be used without upsampling.
The picture is from an older Changstar thread.
Newer DACs may well perform 'better'

a gentle 50kHz LP not even qualifies as a proper reconstruction filter for 192kHz files.
The -155dB noise floor is probably without any signal.
 

gvl

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#6
Looks "normal" for a NOS DAC. Educated guesses are fine but not a replacement for measurements. Metrum moved away from industrial DAC chips they used earlier to in house made R2R modules. I confess to owning a Metrum DAC and liking it more than some other likely better measuring alternatives, just want to see one tested.

SBAF got some data for the Amethyst which is a lower-entry offering, the noise floor is pretty low mostly below -140dB with signal. THD is nothing too spectacular at 48kHz but likely better at higher sampling rates. Most surprising is the white noise response posted there, it looks nothing like a NOS DAC.
 
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solderdude

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#7
I have spoken to Cees a few years ago but this was about the Aurix which is an almost exact copy of a design I published many years before the Aurix came out.
Cees claimed to have been working on it well over 15 years and says indeed it had a lot of similarities.
I designed and built it in a few days. No idea why he would have been working on this so many years and come up with a similar design.
 
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Veri

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#8
I have spoken to Cees a few years ago but this was about the Aurix which is an almost exact copy of a design I published many years before the Aurix came out.
Cees claimed to have been working on it well over 15 years and says indeed it had a lot of similarities.
I designed and built it in a few days. No idea why he would have been working on this so many years and come up with a similar design.
Mediafire link gives error / has no public accessibility :)
 

hvbias

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#10
Looks "normal" for a NOS DAC. Educated guesses are fine but not a replacement for measurements. Metrum moved away from industrial DAC chips they used earlier to in house made R2R modules. I confess to owning a Metrum DAC and liking it more than some other likely better measuring alternatives, just want to see one tested.

SBAF got some data for the Amethyst which is a lower-entry offering, the noise floor is pretty low mostly below -140dB with signal. THD is nothing too spectacular at 48kHz but likely better at higher sampling rates. Most surprising is the white noise response posted there, it looks nothing like a NOS DAC.
I would be interested in seeing measurements of it done by Amir if you were willing :)
 

derp1n

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#11
SBAF got some data for the Amethyst which is a lower-entry offering, the noise floor is pretty low mostly below -140dB with signal.
That's not what those measurements show, nor would the measurement equipment used be able to do so. Read about FFT process gain.
 

gvl

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#12
I would be interested in seeing measurements of it done by Amir if you were willing :)
There are a couple of problems with it. It is the big one... expensive to ship, and the DAC modules have a tendency to eject themselves from the sockets and rattle inside during shipping. Fact. Don't want to risk it. I also have an earlier 16-bit unit which I could probably send to Amir, but it is of less interest at this point given Metrum have switched to 24bit designs.
 

gvl

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#13
That's not what those measurements show, nor would the measurement equipment used be able to do so. Read about FFT process gain.
That's exactly why it would be interesting to see one tested with a precision instrument and an agreed upon methodology. I do not expect a miracle, the extent of my curiosity is to find out how bad Metrum DACs really are :) On my unit, the subjective assessment it is slightly colored yet plenty detailed and very easy to listen to. I do oversample externally with SoX though.
 

amirm

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#14
You guys should contact the company and ask them to send me an evaluation unit. This has worked in the past and it costs nothing to try it.
 

gvl

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#15
Metrum's name has been circulating the "Audiophile circles" for some time now. Given Stereophile hasn't gotten any of their gear to test I suspect they are not very open to objective scrutiny of their tech. Could be wrong.
 

amirm

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#16
Metrum's name has been circulating the "Audiophile circles" for some time now. Given Stereophile hasn't gotten any of their gear to test I suspect they are not very open to objective scrutiny of their tech. Could be wrong.
Probably so but they brag about their high fidelity implementation. I would write to them and ask them if that is so, they should do well in my tests and only then you will believe what they say.
 
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