Well I didn't say I heard 'compression'. I said the effect is like that - music loses dynamics. My guess is it results from the dulling of transients - a burst of noise around a transient can dull its effect.
I agree compression is a non-linear process - noise modulation is most definitely a distortion and can be measured with the right signals and data collection. Only ESS amongst DAC manufacturers admits to the effect, they claim their DAC is better than others. They have a graph of SNR versus DC level from my recollection and if I remember correctly there's about 6dB variation which they say is good.
<edit> For the technical types, here's an interesting paper covering some of the issues: http://www.scalatech.co.uk/papers/jaes496.pdf
I agree compression is a non-linear process - noise modulation is most definitely a distortion and can be measured with the right signals and data collection. Only ESS amongst DAC manufacturers admits to the effect, they claim their DAC is better than others. They have a graph of SNR versus DC level from my recollection and if I remember correctly there's about 6dB variation which they say is good.
<edit> For the technical types, here's an interesting paper covering some of the issues: http://www.scalatech.co.uk/papers/jaes496.pdf
Last edited:
Sounds logical to me. But what about the dulling effect of pre and post ringing of digital filters? As the shape of the pulse is really affected, it must result in high distortion.
The more I learn about NOS DACs, the more logical they become to me. Why, if people can't hear much above 20 kHz anyway (for me it's already rolling off at 16 kHz), bother with filtering and as a result distorting the signal???
The ringing of digital filters is normally at the turnover frequency. So its ultrasonic (at least to me - I think mine gives out around 16kHz like yours 
). However some equiripple digital filters have a time smearing effect - the time domain response is like having an echo added back in - built in discrete reverb. Of course this is a linear distortion so won't show up on FFTs or linearity plots but it must add 'clutter' to the perceived sound.
). However some equiripple digital filters have a time smearing effect - the time domain response is like having an echo added back in - built in discrete reverb. Of course this is a linear distortion so won't show up on FFTs or linearity plots but it must add 'clutter' to the perceived sound.Auditioning the Octave for the first time I was curious if I could hear some HF roll off, which was not the case. I measured frequency bandwidth and some - 2 dB at 20 kHz was confirmed by what could be expected from a NOS design.
Sound wise however, reproducing instruments with a rich upper harmonic spectrum (violin, trumpet) the Octave surpassed other dacs of the delta-sigma and multibit variety (all of them over- and or upsampling) by what can best be described by a gain in "definition".
It seems that our auditory system (ear-brain combination) is more sensible to pureness of transient attack than absolute flatness of frequency bandwidth (as produced by digital filtered / over-/upsampled dacs with their inherent time smearing effects).
I disagree that up/oversampled DACs have inherent time smearing. Certainly their digital filters might have this characteristic but its optional if they're designed with sufficient attention to details. As regards to all of your perceived NOS advantages, I'm with you 100% - particularly on the sound of brass.
I've popped in and out of this thread.
This DAC is a commercial product - not a DIY offering. Its no surprise that they sand the ID off the chips. Nor is the fact that its closed unusual. I don't see DCS giving out any of their inhouse developed stuff either. I think its unreasonable to use this fact as a reason to say "I'll never even listen to it!".
Like many others here, I'm never going to buy it - but thats not because they don't give out all their secrets etc - its because I enjoy the DIY thing and would rather put together my own DAC.
Its a commercial product, they're making a few bob from it, they developed it etc. They are well within their rights.
And at the end of the day, if the customer is satisfied, what does it matter? They don't seem to be charlatans or scam artists, rather providing a good product and service.
Fran
This DAC is a commercial product - not a DIY offering. Its no surprise that they sand the ID off the chips. Nor is the fact that its closed unusual. I don't see DCS giving out any of their inhouse developed stuff either. I think its unreasonable to use this fact as a reason to say "I'll never even listen to it!".
Like many others here, I'm never going to buy it - but thats not because they don't give out all their secrets etc - its because I enjoy the DIY thing and would rather put together my own DAC.
Its a commercial product, they're making a few bob from it, they developed it etc. They are well within their rights.
And at the end of the day, if the customer is satisfied, what does it matter? They don't seem to be charlatans or scam artists, rather providing a good product and service.
Fran
I agree with woodturner-fran's conclusion, because I've spoken to the designer of the Octave on non-audio related topics on several occasions. His work isn't confined to audio and his expertise in other fields is valued by one of our customers.
My impression is that this is an enthusiastic, yet calm, man who has good listening skills. No doubt his products reflect some of his personality. From what I read in the reviews of the Octave is that it's a no frills design with very good value for money.
My impression is that this is an enthusiastic, yet calm, man who has good listening skills. No doubt his products reflect some of his personality. From what I read in the reviews of the Octave is that it's a no frills design with very good value for money.
The same experience with Cees, so a thick +1
Just a bit pity that his other real DIY stuff like electrostatic mid/high panels suffer under the huge interest in the metrum dacs.
It's funny people are using the word "they" when referring to Metrum. I get the distinct feeling that Metrum/Acelec Engineering actually mainly revolves around one man.
On Metrum's website and at the end of the Hifi Critic review the adress of Acelec Engineering is given. A quick look at google maps/streetview reveals this to be a residential area, not a business park.
No doubt he wasn't working alone during design and listening sessions and production is probably done by an OEM similar to the company I work for, but essentially Metrum feels like DIY gone pro.
With a limited budget, you're going to start simple, hence the limited sample rate. By Cees' own admission during a visit to our company, Metrum DACs had received way more positive attention than he had ever expected. Perhaps this holds a promising future...
On Metrum's website and at the end of the Hifi Critic review the adress of Acelec Engineering is given. A quick look at google maps/streetview reveals this to be a residential area, not a business park.
No doubt he wasn't working alone during design and listening sessions and production is probably done by an OEM similar to the company I work for, but essentially Metrum feels like DIY gone pro.
With a limited budget, you're going to start simple, hence the limited sample rate. By Cees' own admission during a visit to our company, Metrum DACs had received way more positive attention than he had ever expected. Perhaps this holds a promising future...
Last edited:
Time to report back. I found out that, apart from Metrum-Acoustics' webshop, there's also one dealer in this country where the Octave can be bought, but more importantly, auditioned. It happened to be at a doable distance from where I live, so I had a good listen to it today.
I took my Primare D20 with me as reference. When auditioning several CD-players 13 years ago, the shop had also included the D20, even though it was just outside my budget. Smart people, the D20 ended up being "the one" for me and has been ever since.
I'm not going to give a review like desciption of what the Octave sounds like, suffice to say it was up there with my reference musically and with the added benefits of better perception of dynamics and better detailing of treble. And I agree with pieter t that with brass instruments that becomes quite apparent.
Oh, and about NOS DA-conversion without any filtering: after having heard this one I'm of the opinion that oversampling and filtering are not necessary. The theoretical drawbacks remain just that: theoretical.
I understand. 192K is so fast and S/PDIF is so complicated that rearranging the bits to accommodate a different interface is beyond the capabilities of today's technology.
You have pretty much a one man outfit, who has come up with using some unusual industrial dac chips. He has managed to find out how to get the spdif stream into the dac chips using "glue logic". He has also managed to pack this into an attractive box and sell it to the mass market for a not outrageous sum of money.
All that can be done here is people whinge about this feature or that feature, or I will never allow it to pollute my ears instead of rejoicing in the lads success.
This fella should be given an award for having a go at a different means of making a DAC. It would appear that its something that his customers are happy with. Its not a scam, he doesn't make false claims for it and it does what it says on the tin.
Jeez, what more do you want! Oh yeah - the secret chips and I suppose the logic so you can go build one yourself?
I am not a customer, I haven't heard the metrum dac, I don't know the maker, but tell you what - I admire him for having a go. Yes, maybe he is making it in a shed at the back of his house. So what! If he was in a big factory with polished floors you can add another zero to that price.
Jeez, the negative posters here need to cop the hell on.
Fran
All that can be done here is people whinge about this feature or that feature, or I will never allow it to pollute my ears instead of rejoicing in the lads success.
This fella should be given an award for having a go at a different means of making a DAC. It would appear that its something that his customers are happy with. Its not a scam, he doesn't make false claims for it and it does what it says on the tin.
Jeez, what more do you want! Oh yeah - the secret chips and I suppose the logic so you can go build one yourself?
I am not a customer, I haven't heard the metrum dac, I don't know the maker, but tell you what - I admire him for having a go. Yes, maybe he is making it in a shed at the back of his house. So what! If he was in a big factory with polished floors you can add another zero to that price.
Jeez, the negative posters here need to cop the hell on.
Fran
That is just FOR YOU are not necessary. For people that don't like to hear fake alias products, is important.
I don't like to hear brass high-frequency sounds "folded" back into the bass section of the spectrum, you might like them.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.