[rkt31]

I am not an electronics engineer but a bit curious about r2r and nos DACs. are all r2r dacs nos if not then how do r2r DACs implement oversampling? if nos DACs do not do oversampling then how nos DACs handle variable sample rates ? are all nos DACs r2r ? can anybody help in explaining in simple terms ?

 

[astrostar59]

I am not an electronics engineer but a bit curious about r2r and nos DACs. are all r2r dacs nos if not then how do r2r DACs implement oversampling? if nos DACs do not do oversampling then how nos DACs handle variable sample rates ? are all nos DACs r2r ? can anybody help in explaining in simple terms ?

Basically R-2R DACs handle 96K 18 bit. Some chips can handle more, but I have referring to the AD1865 which is in my own DAC. If I feed it samples over that rate, it truncates them but still plays music.
 
The creation of Delta-Sigma chips was to simplify the filtering of artefacts and out of band noise. The debate to which is best and to the logic of the 2 systems goes on, but if you dig around many of the top tier DACs are now R-2R. Some can do higher sample rates by using 4 or 8 chips, others like MSB and TotalDAC use more resistors for the extra resolution.
 
If you fancy doing a DIY there are boards available to build your own. Or the Audio Note kits for example which come with everything to assemble a complete working DAC.

 

[rkt31]

@astrostar59, thanks for the quick reply. now I understand that r2r DACs too don't updample and by default these take maximum 96khz sample rate.

 

[astrostar59]

@astrostar59, thanks for the quick reply. now I understand that r2r DACs too don't updample and by default these take maximum 96khz sample rate.

This applies to some chip but confusingly not all. The AD1865 is according so some the best sounding 'old style' chip.
 
Maybe your next step is get to hear an R-2R DAC? It may float your boat.

 

[rb2013]

I am not an electronics engineer but a bit curious about r2r and nos DACs. are all r2r dacs nos if not then how do r2r DACs implement oversampling? if nos DACs do not do oversampling then how nos DACs handle variable sample rates ? are all nos DACs r2r ? can anybody help in explaining in simple terms ?

Some NOS R2R like the TD1541 use no upsampling. But only do 16/44. Some like PCM1704 do 24bit 96k by using the companion DF1704 filter. It can actually handle 784k, with a different filter scheme. Native or upsampled.

 

[Articnoise]

I am not an electronics engineer but a bit curious about r2r and nos DACs. are all r2r dacs nos if not then how do r2r DACs implement oversampling? if nos DACs do not do oversampling then how nos DACs handle variable sample rates ? are all nos DACs r2r ? can anybody help in explaining in simple terms ?

 

Yes all NOS DACs are R2R. The DS (delta sigma) modulation has to be done in frequencies much high than native PMC/red book are recorded/playing at. 

 

R2R DAC chips are designed in a way that doesn’t require oversampling for the digital ->analogue conversion function, as all delta sigma does. That doesn’t mean that a R2R dac chip can’t be used to do oversampling. The difference is that oversampling or no oversampling can be chosen by the designer. In some case also by the user, as for example in Audio GDs Master 7 and 11 DACs.

 

A NOS DAC is always playing the native sample rate. The native sample rate is the frequency that the recording has, or in some special cases, that rate that the file has after upsample in a computer. If the sample rate is 44.1 KHz (red book) all dac chip can do that. If it’s higher it will depend on the specific digital to analogue chip and also the input limitation of the USB/SPDIF/AES. Most R2R dac chip that are used in modern DACs (that are sold new today) can at least play 96 KHz without oversampling. Some can play much higher thou.

 

The biggest difference IMO between a non-oversampling DAC and an oversampling DAC is in the filtering. A NOS DAC can be made without digital filtering, while all oversampling DACs use one to filtering out the artifacts that is left from the oversampling process. Even if most NOS DAC use digital or analogue filers they don’t need to be as profound as in oversampling or DS.   

 

[rb2013]

   

Yes all NOS DACs are R2R. The DS (delta sigma) modulation has to be done in frequencies much high than native PMC/red book are recorded/playing at. 

 

R2R DAC chips are designed in a way that doesn’t require oversampling for the digital ->analogue conversion function, as all delta sigma does. That doesn’t mean that a R2R dac chip can’t be used to do oversampling. The difference is that oversampling or no oversampling can be chosen by the designer. In some case also by the user, as for example in Audio GDs Master 7 and 11 DACs.

 

A NOS DAC is always playing the native sample rate. The native sample rate is the frequency that the recording has, or in some special cases, that rate that the file has after upsample in a computer. If the sample rate is 44.1 KHz (red book) all dac chip can do that. If it’s higher it will depend on the specific digital to analogue chip and also the input limitation of the USB/SPDIF/AES. Most R2R dac chip that are used in modern DACs (that are sold new today) can at least play 96 KHz without oversampling. Some can play much higher thou.

 

The biggest difference IMO between a non-oversampling DAC and an oversampling DAC is in the filtering. A NOS DAC can be made without digital filtering, while all oversampling DACs use one to filtering out the artifacts that is left from the oversampling process. Even if most NOS DAC use digital or analogue filers they don’t need to be as profound as in oversampling or DS.   

Great summary explanation.
 
Here is more info for those curious:
http://www.mother-of-tone.com/conversion.htm
http://funwithaudio.blogspot.com/2012/01/today-in-electronics-everything-is-made.html

 

[astrostar59]

 
 
 
Recently bought an ex-demo (like new, not SE version) AMR DP-777 DAC here in the UK. It is for use in my second system which is Stax 007A headphones, KGSShv Carbon and Mac Mini server.
 
I fancied trying the AMR after talking to owners and reading various reviews. It has 2 chips, one that does NOS R-2R bit perfect, the other a more common DS chip. I am not interested in the DS chip, and will use only RedBook native files. I will feed it SPDIF via my M2Tech stack and Mac Mini USB output.
 
Trouble is I can't hear it yet as waiting for the DIY Carbon. It looks very well built and you can see the valves lit inside. I will report back once I have my amp in place. Be interesting to hear how it compares to my recently sold Audio Note Kit DAC 4.1 which was heavily modded. This DAC cost me less so some wiggle room. I will lug this DAC back to Spain with me as a fall back to my main system.
 

 

 

 

[Luckbad]

Starting to think about downsizing in cost and space. Going to mention to you folks here before I list it that I might have a Sonic Frontiers SFD-1 MK-II going up for sale shortly. Gold face with matched pair of 6N23P-EV from Parts Connexion and I believe a matched pair of JJ as well. Inputs are AES, TOSLINK, and coax S/PDIF.

 

[Joeybgood]

Question...... Theta DS Pro Gen V - A / Sonic Frontiers SFD-2 MK II.... both highly regarded R2R DACs from the mid 90s... both MSRP'd for approx the same price. Not looking for people's preference or impressions, just wondering if you think that an even up trade of  these two DACs is a fair trade? Thoughts?

 

[doctorjazz]

Don't know how they compare sonically, but the Theta sells used for quite a bit more, at least when I've seen it listed. I've read great things about both.

 

[Joeybgood]

Don't know how they compare sonically, but the Theta sells used for quite a bit more, at least when I've seen it listed. I've read great things about both.

Do you recall approx what price you've seen the MK II listed for by chance? I've just recently started to look around at the MK II as I'd like to experience a nice R2R tube implemented DAC and the AN DAC 5 Special and SIgnature are a weeeee bit out of my range. There is currently one listed on Ebay for $1795 which is comparable to, if not even a bit higher than, what Ive seen Theta Gen V-As going for. I'm guessing this $1795 listing is on the rather high side?

 

[doctorjazz]

It's been a while, but I think the prices for the Sonic Frontiers have been around there, $1500-2000. I have seen the Theta for considerably more (the Gen V), but I wouldn't swear to these numbers.

 

[astrostar59]

It's been a while, but I think the prices for the Sonic Frontiers have been around there, $1500-2000. I have seen the Theta for considerably more (the Gen V), but I wouldn't swear to these numbers.

My worry with gear this old is it may need a recap. Also it may have been messed with or had multiple owners. Some of the challenges in finding great condition gear this old IMO.
 
Personally I would rather go for a new Audio Note Kit DAC where I know everything is brand new and has warranty, or a very good condition and not so old DAC.
 
I recently bought a used Audio Note DAC 5 Special V2 which is 2008/9 but is in great condition. The Audio Note KIT DACs are MUCH cheaper and can be upgraded in a logical manner to become giant killers, and the circuits are pretty simple to work with, no tiny components. I recently sold my DAC 4 Kit which was heavily modded and it sounded  fantastic. I wish I could have kept it but I need the funds to go towards the DAC 5.
 
The other units to think about may be some of the more recent Lampizator units (PCB ones, not hard wired). They can also be tweaked up, though I think the Audio Note kits are better performance v cash spent.

 

[Joeybgood]

  My worry with gear this old is it may need a recap. Also it may have been messed with or had multiple owners. Some of the challenges in finding great condition gear this old IMO.
 
Personally I would rather go for a new Audio Note Kit DAC where I know everything is brand new and has warranty, or a very good condition and not so old DAC.
 
I recently bought a used Audio Note DAC 5 Special V2 which is 2008/9 but is in great condition. The Audio Note KIT DACs are MUCH cheaper and can be upgraded in a logical manner to become giant killers, and the circuits are pretty simple to work with, no tiny components. I recently sold my DAC 4 Kit which was heavily modded and it sounded  fantastic.
 
The other units to think about may be some of the more recent Lampizator units (PCB ones, not hard wired). They can also be tweaked up.

Tks again Julian.. those are Definitely options I am exploring as well... I just don't want to drop TOO much as I would love to snap up a sweet deal like you did with your AN, but even a SWEET deal is not inexpensive, of course. The vintage Theta I own was inspected and thoroughly scoured over by a long time Krell Audio tech and  everything tested out well within specs and he replaced the front panel toggles so I was comfortable pulling the trigger on it. It's sounds amazing.. truly.. but I really don't wish to have 2 vintage 20+ yr old DACs(5 dacs total) so I'm leaning towards selling and/or trading my Theta Gev V-A for a highly regarded NOS R2R tube DAC. Hope I don't regret it!! Thanks for all your input on this as always!!!