Post by optical on Aug 22, 2022 8:58:47 GMT
Just to update my DAC journey:
On my quest to find a DAC that (as near as possibly) 'does it all'. I've been trying out quite a few recently. My requirements may not be the same as eveyone I suspect but over the last few years it seems that valve DAC's get me 'closer' to my ideal. That's an ideal of textural realism, air and space between notes and an expansive holographic soundstage. Of course if accuracy, timing, realistic scale etc aren't there then I'm not going to plumb for a warm, woolly DAC at the expense of those things just because it sounds lush and romantic.
Truth is if my TDA1541 design DAC with C3G valve output stage played 24 bit depth I'd be absolutely happy to stick with that, it sounds awesome . . . but a lot of my library is 24 bit. Not that I think 24 bit sounds that much or even any better in a lot of cases, it's simply because when they were available I chose the higher bit depth because well, why not? I had a DAC that could play it at the time so it just made sense.
I could go and resample all my library to 16 bit and happily live with that DAC, but I'd rather have the option and if possible even improve upon that particular DAC.
What have I been through recently? Well I'll list them here:
Metrum NOS Mini DAC 'Octave'. - Unique output chips coupled directly to the output stage (well actually they kind of are the output stage) NOS design, lovely timbral texture on notes if a little laid back presentation, unfortunately the power supply was the lower spec version and wasn't as advertised so it went back. Also struggled on some material over 96k sampling rate.
Denafrips dac-8 pro mk1 - PCM1702 based. Lots of caps, big toroidal transformer. Great sound, could probably live with it but slightly less 3D that my TDA1541 (and that's what we're trying to beat here remember).
Audio GD NOS 19 DAC (not to be confused with 'DAC19') - PCM1704 based - Very well designed power supply, again similar sound to the denafrips with a welcome 'liveliness' to the sound without getting shrill or fatiguing. Loses out on texture and body compared to valve DAC's (again).....
So as my 'dac for every day of the week' journey continues, I happened across an interesting design. (It was becoming clearer that I do need that sprinkling of valve sound signature for things to sound textured and full bodied to my ears).
It's loosely based on an Audio Note design. Yes I know a lot of their kit gets scoffed at because it imparts a sonic signature ie colouration to the sound, their speakers certainly do but their DAC's get almost universal approval for sheer musicality, that's what I'm interested in here.
Using an AD1865 chip in a valve rectified circuit and going through a valve buffer, the design also gives me an opportunity to use a couple of my favourite valves. Namely a 6n23P in the buffer position and a 6X4 as a rectifier, specifically Reflektor and Tung Sol ones respectively.
As the circuit employs a chinese 6~4 valve as a rectifier originally, a 6~4 to 6X4 adapter is required. I use the same one that I used in my recent phono stage build/modification.
First listening impressions are remarkably favourable for my system. It's a very smooth listen but retains all the details that I can detect. Slightly recessed soundstage in width but it has good layering and depth poking out in front of and behind the speakers, a good sign indeed as with the potential mods all of these attributes can be improved upon to some degree.
Most important aspect is it's ability to play music, without worry of fatigue or shrillness in any department. I quite happily sat there for a few hours listening to it fresh out of the box with cheap Chinese valves and all the standard wiring and sockets etc.
Now to hack it apart and potentially mess things up and upset the balance . . . .
New RCA sockets for the outputs (not super expensive just CMC 'red copper' ones).
CCC wiring from board to RCA outputs.
Did away with the RCA digital coax input and hard wired a 75ohm Canare cable straight to the board.
As is standard procedure now with all DAC's/preamp's/phono stages etc, these tweaks should give an immediate lift in performance. Replacing cheap and poor signal carrying elements of a design as well as cutting out unnecessary connections is never going to be a bad thing and in my experience always has a large positive effect.
Now comes a bit of valve rolling. Initially I stuck a trusty Vohskod 'rocket' 6n23P valve in the buffer stage along with a Tesla 6X4 for the rectifier. Things sounded really good at this point but just out of curiosity (and as I knew the Tung Sol 6X4 is a 'better' valve) I stuck in a Reflektor 6n23P and the trusty Tung Sol 6X4WA.
Listening to the DAC now with these upgrades was an absolute joy. Honestly I mean everything is there. Timing is absolutely spot on, it's snappy but smooth, very extended on both low's and highs but also has that ability to not show it's entire hand all at once. Most DAC's don't do it but the best I've heard have this ability to have you listening along thinking 'yeah that's a really great sound' then suddenly BAM! It reaches even lower/higher/hits harder and plunges new depths of performance you really weren't expecting. Demonstrating a rare ability to present new elements of songs you know inside out. A huge delight.
Here we reach a tipping point, do I:
A) Enjoy this surprisingly good DAC for what it is (a really great sounding piece of equipment regardless of price)
or
B) Carry on modding it and really start to go to town . . . .
I think you know which option I chose (otherwise the thread would be finished right here) so without further adoo . . . .
Out with the old . . .
In with the new . . .
Smoothing caps for the regulators aren't terrible but there are better available for relatively little outlay, so picked up some much better spec and slightly more capacitance ones from Wurth.
Main power supply caps have also been upgraded by ones with better spec although same capacitance. Some nice ones from cornell dubilier, although I also bought some bigger (in value) Nichicon ones to replace the standard Nichicon ones if need be but went with the better spec ones.
Lastly the output coupling caps were replaced with some very neat Amtrans ones (not seen these before) they look really nice and will be a definite upgrade over the WIMA ones that come as standard. As space was a factor here they fit the brief absolutely perfectly I would say.
So some fairly major work undertaken . . . even with all that taken into account I wasn't prepared for what I heard upon first switch on . . . . dry, flat boring sound. Could have been listening to any cheap DAC to be honest. Not a hint of the airy space between instruments ot textural 'tone' previously provided by the same DAC.
Okay time to calm down, as Oli and others have told me caps can take ages to 'burn in'. I myself have experienced this many times but never have I heard such a drastic change in equipment after changing any component, be it caps, power supply, valves etc etc.
Having said that all the caps and valves were brand new when I first listened to the DAC, so how could replacing them with all better spec ones result in a massively inferior sound?
I stuck with it leaving it on for a few hours at a time then allowing the caps to properly discharge before turning it on again, I was hoping the 'skin' effect would gradually improve the sound doing this over a couple of days . . . .
Came to listen to it again the next day after leaving it playing through the night, no change. Flat and boring presentation. The 'snappiness' was gone, no foot tapping what so ever.
Okay so I hadn't given it anything like the 100 hours (or whatever amount of time it can take for caps to break in) but surely after 20+ hours if there was going to be any change there should be 'some' improvement?
So, I had another look at all the connections, traced the signal path for any bad joints or potential crosstalk/signal bleed etc etc. Everything looked fine . . . .
The only thing I noticed (and it was only when I gave it a little wiggle) was that the chassis ground (which was connected to one of the RCA output ground's) came away quite easily. The joint actually looked okay but you never know with these CMC sockets as the outer (ground/negative) part of the assembly is so thick it's hard to get a good connection. As you can see from the pic I actually sometimes wind the exposed wire around the nub and solder it from there (as it holds the wire on anyway) then cut away any excess exposed cable.
Well, I re-soldered it anyway even though I didn't think it was causing any issues as although it came away quite easily it was still 'connected' as such.
NO WAY, I thought as I listened to the first note out of the thing after doing that.
It's back, it's back with a bang and with new found authority.
Perhaps the connection was too resistive, perhaps it was not connected 'enough', well whatever the reason, it transformed things back to how they were before. Well no actually I could now hear all of the upgrades I had just made to the thing.
It wasn't the same impact changing the wiring/connectors/valves had initially, but it was back to that sound signature (which i was hesitant to change anyway) but with more. A bit more texture, a bit more bite. Bass was deeper and incredibly smooth; I'm talking spread around your room like it's being poured out of a large paint tin 'smooth'.
At this point I don't care if it improves any more or not (although I suspect it will a little as the caps still only have 20 something hours on them as do the valves to be fair).
In summary, I'm happy. Happy that I didn't f*** up a lovely sounding DAC (well not for that long anyway) and happy that I appear (for the time being) to have found a cheap DAC that does everything I want it to do, and perhaps even a little bit more.
All in including all parts/valves/sockets/caps etc it doesn't owe me much more than £250.
Cheers
Link to DAC for those interested:
www.ebay.co.uk/itm/225097948868
On my quest to find a DAC that (as near as possibly) 'does it all'. I've been trying out quite a few recently. My requirements may not be the same as eveyone I suspect but over the last few years it seems that valve DAC's get me 'closer' to my ideal. That's an ideal of textural realism, air and space between notes and an expansive holographic soundstage. Of course if accuracy, timing, realistic scale etc aren't there then I'm not going to plumb for a warm, woolly DAC at the expense of those things just because it sounds lush and romantic.
Truth is if my TDA1541 design DAC with C3G valve output stage played 24 bit depth I'd be absolutely happy to stick with that, it sounds awesome . . . but a lot of my library is 24 bit. Not that I think 24 bit sounds that much or even any better in a lot of cases, it's simply because when they were available I chose the higher bit depth because well, why not? I had a DAC that could play it at the time so it just made sense.
I could go and resample all my library to 16 bit and happily live with that DAC, but I'd rather have the option and if possible even improve upon that particular DAC.
What have I been through recently? Well I'll list them here:
Metrum NOS Mini DAC 'Octave'. - Unique output chips coupled directly to the output stage (well actually they kind of are the output stage) NOS design, lovely timbral texture on notes if a little laid back presentation, unfortunately the power supply was the lower spec version and wasn't as advertised so it went back. Also struggled on some material over 96k sampling rate.
Denafrips dac-8 pro mk1 - PCM1702 based. Lots of caps, big toroidal transformer. Great sound, could probably live with it but slightly less 3D that my TDA1541 (and that's what we're trying to beat here remember).
Audio GD NOS 19 DAC (not to be confused with 'DAC19') - PCM1704 based - Very well designed power supply, again similar sound to the denafrips with a welcome 'liveliness' to the sound without getting shrill or fatiguing. Loses out on texture and body compared to valve DAC's (again).....
So as my 'dac for every day of the week' journey continues, I happened across an interesting design. (It was becoming clearer that I do need that sprinkling of valve sound signature for things to sound textured and full bodied to my ears).
It's loosely based on an Audio Note design. Yes I know a lot of their kit gets scoffed at because it imparts a sonic signature ie colouration to the sound, their speakers certainly do but their DAC's get almost universal approval for sheer musicality, that's what I'm interested in here.
Using an AD1865 chip in a valve rectified circuit and going through a valve buffer, the design also gives me an opportunity to use a couple of my favourite valves. Namely a 6n23P in the buffer position and a 6X4 as a rectifier, specifically Reflektor and Tung Sol ones respectively.
As the circuit employs a chinese 6~4 valve as a rectifier originally, a 6~4 to 6X4 adapter is required. I use the same one that I used in my recent phono stage build/modification.
First listening impressions are remarkably favourable for my system. It's a very smooth listen but retains all the details that I can detect. Slightly recessed soundstage in width but it has good layering and depth poking out in front of and behind the speakers, a good sign indeed as with the potential mods all of these attributes can be improved upon to some degree.
Most important aspect is it's ability to play music, without worry of fatigue or shrillness in any department. I quite happily sat there for a few hours listening to it fresh out of the box with cheap Chinese valves and all the standard wiring and sockets etc.
Now to hack it apart and potentially mess things up and upset the balance . . . .
New RCA sockets for the outputs (not super expensive just CMC 'red copper' ones).
CCC wiring from board to RCA outputs.
Did away with the RCA digital coax input and hard wired a 75ohm Canare cable straight to the board.
As is standard procedure now with all DAC's/preamp's/phono stages etc, these tweaks should give an immediate lift in performance. Replacing cheap and poor signal carrying elements of a design as well as cutting out unnecessary connections is never going to be a bad thing and in my experience always has a large positive effect.
Now comes a bit of valve rolling. Initially I stuck a trusty Vohskod 'rocket' 6n23P valve in the buffer stage along with a Tesla 6X4 for the rectifier. Things sounded really good at this point but just out of curiosity (and as I knew the Tung Sol 6X4 is a 'better' valve) I stuck in a Reflektor 6n23P and the trusty Tung Sol 6X4WA.
Listening to the DAC now with these upgrades was an absolute joy. Honestly I mean everything is there. Timing is absolutely spot on, it's snappy but smooth, very extended on both low's and highs but also has that ability to not show it's entire hand all at once. Most DAC's don't do it but the best I've heard have this ability to have you listening along thinking 'yeah that's a really great sound' then suddenly BAM! It reaches even lower/higher/hits harder and plunges new depths of performance you really weren't expecting. Demonstrating a rare ability to present new elements of songs you know inside out. A huge delight.
Here we reach a tipping point, do I:
A) Enjoy this surprisingly good DAC for what it is (a really great sounding piece of equipment regardless of price)
or
B) Carry on modding it and really start to go to town . . . .
I think you know which option I chose (otherwise the thread would be finished right here) so without further adoo . . . .
Out with the old . . .
In with the new . . .
Smoothing caps for the regulators aren't terrible but there are better available for relatively little outlay, so picked up some much better spec and slightly more capacitance ones from Wurth.
Main power supply caps have also been upgraded by ones with better spec although same capacitance. Some nice ones from cornell dubilier, although I also bought some bigger (in value) Nichicon ones to replace the standard Nichicon ones if need be but went with the better spec ones.
Lastly the output coupling caps were replaced with some very neat Amtrans ones (not seen these before) they look really nice and will be a definite upgrade over the WIMA ones that come as standard. As space was a factor here they fit the brief absolutely perfectly I would say.
So some fairly major work undertaken . . . even with all that taken into account I wasn't prepared for what I heard upon first switch on . . . . dry, flat boring sound. Could have been listening to any cheap DAC to be honest. Not a hint of the airy space between instruments ot textural 'tone' previously provided by the same DAC.
Okay time to calm down, as Oli and others have told me caps can take ages to 'burn in'. I myself have experienced this many times but never have I heard such a drastic change in equipment after changing any component, be it caps, power supply, valves etc etc.
Having said that all the caps and valves were brand new when I first listened to the DAC, so how could replacing them with all better spec ones result in a massively inferior sound?
I stuck with it leaving it on for a few hours at a time then allowing the caps to properly discharge before turning it on again, I was hoping the 'skin' effect would gradually improve the sound doing this over a couple of days . . . .
Came to listen to it again the next day after leaving it playing through the night, no change. Flat and boring presentation. The 'snappiness' was gone, no foot tapping what so ever.
Okay so I hadn't given it anything like the 100 hours (or whatever amount of time it can take for caps to break in) but surely after 20+ hours if there was going to be any change there should be 'some' improvement?
So, I had another look at all the connections, traced the signal path for any bad joints or potential crosstalk/signal bleed etc etc. Everything looked fine . . . .
The only thing I noticed (and it was only when I gave it a little wiggle) was that the chassis ground (which was connected to one of the RCA output ground's) came away quite easily. The joint actually looked okay but you never know with these CMC sockets as the outer (ground/negative) part of the assembly is so thick it's hard to get a good connection. As you can see from the pic I actually sometimes wind the exposed wire around the nub and solder it from there (as it holds the wire on anyway) then cut away any excess exposed cable.
Well, I re-soldered it anyway even though I didn't think it was causing any issues as although it came away quite easily it was still 'connected' as such.
NO WAY, I thought as I listened to the first note out of the thing after doing that.
It's back, it's back with a bang and with new found authority.
Perhaps the connection was too resistive, perhaps it was not connected 'enough', well whatever the reason, it transformed things back to how they were before. Well no actually I could now hear all of the upgrades I had just made to the thing.
It wasn't the same impact changing the wiring/connectors/valves had initially, but it was back to that sound signature (which i was hesitant to change anyway) but with more. A bit more texture, a bit more bite. Bass was deeper and incredibly smooth; I'm talking spread around your room like it's being poured out of a large paint tin 'smooth'.
At this point I don't care if it improves any more or not (although I suspect it will a little as the caps still only have 20 something hours on them as do the valves to be fair).
In summary, I'm happy. Happy that I didn't f*** up a lovely sounding DAC (well not for that long anyway) and happy that I appear (for the time being) to have found a cheap DAC that does everything I want it to do, and perhaps even a little bit more.
All in including all parts/valves/sockets/caps etc it doesn't owe me much more than £250.
Cheers
Link to DAC for those interested:
www.ebay.co.uk/itm/225097948868
, I will question the direct coax connection, not the direct part but the cable, since I've generally found silver cable to be better for digital signals, although I don't know how easy it would be for you to try a different cable the way you have done it. Well done anyway. 
