Eron,
impedance matching will help but it's not going to change the sonic signature of the stock model.
impedance matching will help but it's not going to change the sonic signature of the stock model.
thanks, ra7.
I am going to wait until the audipax and the super pro arrive, do a lot of listening and, if I decide to upgrade the dac, try to sum up what is needed (like, just the ap-amp and using batteries, for instance), and have a qualified technician to do the change for me. Nonetheless, this thread is great, thanks to you guys (danke sehr, martin!).
I am going to wait until the audipax and the super pro arrive, do a lot of listening and, if I decide to upgrade the dac, try to sum up what is needed (like, just the ap-amp and using batteries, for instance), and have a qualified technician to do the change for me. Nonetheless, this thread is great, thanks to you guys (danke sehr, martin!).
Hallo Eron!
Regarding impedance matching, there is no need to do that for the super pro dac! In stock form, there are already output caps with a capacitance of 47uF, and thanks to the opamp-based output stage the output impedance is very low and capable of quite high current delivery. So, you can easily drive both high and low impedance loads with the stock unit, be it a passive 10k pot or a active preamp of any kind.
Only reason I brought this up is that member Andrea mentioned you might go for lower value output caps because of the limited space (for example, a 4,7uF Mundorf Supreme cap is really huge!), and this is where one has to be careful. With output caps of, say, 1,0uF you will need a higher input impedance of the following stage (active pre or a 100k pot) to avoid any low frequency cut off.
One more thing: I listened to the super pro in stock form and after some mods, and then finally with the battery. And I would say that perhaps none of the tweaks I did brought the dac that much forward in sound quality than the battery thing. So I can give you the honest advice to just leave the dac as it comes and just add a decent battery supply (perhaps a 12V / 7,2Ah Panasonic SLA with charger), and just listen.
As Andrea once said, the stock opamp LT1364 is quite a good opamp, and the stock output caps (epcos smd, tantalums I think) also do a quite nice job after some break in.
I really think that the power supply is one of the most important parts. In the end, every analogue output signal is a somehow modulated form of the power supply's voltage and current. Therefore, wall wart adapters are very nice when you intend to power a small battery charger, a telephone, a wireless router or something like that, but not a dac or preamp!!
In this regard a battery has (at least) the following advantages:
- complete isolation from the mains ac
- less noise
- no regulation (neither series a la 78XX nor shunt!) needed
Enjoy!
Martin
Regarding impedance matching, there is no need to do that for the super pro dac! In stock form, there are already output caps with a capacitance of 47uF, and thanks to the opamp-based output stage the output impedance is very low and capable of quite high current delivery. So, you can easily drive both high and low impedance loads with the stock unit, be it a passive 10k pot or a active preamp of any kind.
Only reason I brought this up is that member Andrea mentioned you might go for lower value output caps because of the limited space (for example, a 4,7uF Mundorf Supreme cap is really huge!), and this is where one has to be careful. With output caps of, say, 1,0uF you will need a higher input impedance of the following stage (active pre or a 100k pot) to avoid any low frequency cut off.
One more thing: I listened to the super pro in stock form and after some mods, and then finally with the battery. And I would say that perhaps none of the tweaks I did brought the dac that much forward in sound quality than the battery thing. So I can give you the honest advice to just leave the dac as it comes and just add a decent battery supply (perhaps a 12V / 7,2Ah Panasonic SLA with charger), and just listen.
As Andrea once said, the stock opamp LT1364 is quite a good opamp, and the stock output caps (epcos smd, tantalums I think) also do a quite nice job after some break in.
I really think that the power supply is one of the most important parts. In the end, every analogue output signal is a somehow modulated form of the power supply's voltage and current. Therefore, wall wart adapters are very nice when you intend to power a small battery charger, a telephone, a wireless router or something like that, but not a dac or preamp!!
In this regard a battery has (at least) the following advantages:
- complete isolation from the mains ac
- less noise
- no regulation (neither series a la 78XX nor shunt!) needed
Enjoy!
Martin
RA7, don't humiliate me...
ra7, I am 55. When I was a teenager, I tried to build small amplifiers, a mixer channel for my band, and never ever succeeded. I used to joke, saying that the guys at the electronics stores sold me "stale colored beans". I gave definitively up when I tried to build a signal injector (to find out what went wrong in my projects), and it too failed!!!😕
What I mean is, I read your posts with a mix of admiration and envy (perhaps the same some people would feel when watching me on a stage, playing my bass - I mean, each one has a talent, right?).
My son just joined the army, and will become an electronics specialist in the air force. How is that for a sweet revenge? In the Israeli air force, no less?🙂
That being said, I landed in this thread because I want a low cost DAC to improve the sound in my system. I was an audio journalist back in Brazil, and I have heard many battery-powered systems, so Martin's claims make perfect sense - and I feel confident I am capable of pulling out this level of intervention.
I know what an op-amp is, but I never heard of "OPT". Please educate me.
And please excuse me if I am verbose: the fact is, I love to write!
ra7, I am 55. When I was a teenager, I tried to build small amplifiers, a mixer channel for my band, and never ever succeeded. I used to joke, saying that the guys at the electronics stores sold me "stale colored beans". I gave definitively up when I tried to build a signal injector (to find out what went wrong in my projects), and it too failed!!!😕
What I mean is, I read your posts with a mix of admiration and envy (perhaps the same some people would feel when watching me on a stage, playing my bass - I mean, each one has a talent, right?).
My son just joined the army, and will become an electronics specialist in the air force. How is that for a sweet revenge? In the Israeli air force, no less?🙂
That being said, I landed in this thread because I want a low cost DAC to improve the sound in my system. I was an audio journalist back in Brazil, and I have heard many battery-powered systems, so Martin's claims make perfect sense - and I feel confident I am capable of pulling out this level of intervention.
I know what an op-amp is, but I never heard of "OPT". Please educate me.
And please excuse me if I am verbose: the fact is, I love to write!
Super Pro and Women - best eaten plain!
Danke, danke, Martin!
I will definitely do as you suggest, and do it timely. What I have learned from my experience as equipment reviewer is that you have to go slowly when adjusting a system.
If we really love the music, we don't go like crazy adding this and that, because doing so you lose the perspective, what "this and that" really do to what is really important: the music.
Es freut mich sehr, dich kennengelernt haben! Translation: "DIY Rules!"😉
Danke, danke, Martin!
I will definitely do as you suggest, and do it timely. What I have learned from my experience as equipment reviewer is that you have to go slowly when adjusting a system.
If we really love the music, we don't go like crazy adding this and that, because doing so you lose the perspective, what "this and that" really do to what is really important: the music.
Es freut mich sehr, dich kennengelernt haben! Translation: "DIY Rules!"😉
Eron,
You and I are not too dissimilar. I too have not great soldering skills, and the dac with OPTs (output transformers) I had, was a friend's. I have to get my own and do the mod, which I am dreading.
Like Martin said, try the batteries. But the OPTs, because I have heard them, are such a stunning improvement. They will totally change the sound and take to another level.
And I agree about your opinion on changing too much too fast in your system.
Best of luck!
You and I are not too dissimilar. I too have not great soldering skills, and the dac with OPTs (output transformers) I had, was a friend's. I have to get my own and do the mod, which I am dreading.
Like Martin said, try the batteries. But the OPTs, because I have heard them, are such a stunning improvement. They will totally change the sound and take to another level.
And I agree about your opinion on changing too much too fast in your system.
Best of luck!
Hi guys,
If you want something a little easier to mess with (a LOT easier) get yourself the big cs4398 dac board and get a small case for it. You can swap opamps all day long if that is what you want, and adding OPTs is a cake walk. And you wont go blind doing it. It's a step above the Super Pro by any measure. Ive tried 8 different OPTs so far and could live happily with most of them.
Just my two cents.
Best, Bill
If you want something a little easier to mess with (a LOT easier) get yourself the big cs4398 dac board and get a small case for it. You can swap opamps all day long if that is what you want, and adding OPTs is a cake walk. And you wont go blind doing it. It's a step above the Super Pro by any measure. Ive tried 8 different OPTs so far and could live happily with most of them.
Just my two cents.
Best, Bill
Hello Bill!
Do you have a link to a website where are theoretical aspects of output transformers for audio are explained, like how to wire them up, which type of transformer to use, impedance ratios and so on?
I googled around a bit and tried the search function of the forum but wasn't able to find something real useful.
I'm a total newbe when it comes to OPTs. Is it true that one can wire them directly to the output pins of a dac chip? And if so, does it have to be a v-out dac or a current-out dac, or is both possible?
Is it also possible to use OPTs for a very simple dac circuit like the TDA1543, insetad of it's passive i/v conversion?
Thanks a lot!
Martin
Do you have a link to a website where are theoretical aspects of output transformers for audio are explained, like how to wire them up, which type of transformer to use, impedance ratios and so on?
I googled around a bit and tried the search function of the forum but wasn't able to find something real useful.
I'm a total newbe when it comes to OPTs. Is it true that one can wire them directly to the output pins of a dac chip? And if so, does it have to be a v-out dac or a current-out dac, or is both possible?
Is it also possible to use OPTs for a very simple dac circuit like the TDA1543, insetad of it's passive i/v conversion?
Thanks a lot!
Martin
Bill,
are you talking about one of the ebay dacs? Can you provide a link? I would like to get one of those.
Thanks!
are you talking about one of the ebay dacs? Can you provide a link? I would like to get one of those.
Thanks!
Hi Bill,
thanks for the heads up.
are you referring to (something like) this(?):
http://www.diyaudio.com/forums/digital-source/107932-cs4398-evaluation-board-universal-dac.html I confess I found it pretty complicated...
Or is there a "big cs4398 dac board" kit?
thanks for the heads up.
are you referring to (something like) this(?):
http://www.diyaudio.com/forums/digital-source/107932-cs4398-evaluation-board-universal-dac.html I confess I found it pretty complicated...
Or is there a "big cs4398 dac board" kit?
I guess Bill is referring to something like this:
Gigawork 24/192 Up-sampling DAC DA CONVERTER w/ USB kit bei eBay.de: CD Players Recorders (endet 29.03.10 10:00:30 MESZ)
Or that:
Hi End 24/192 DAC DA CONVERTER CS8416+CS8421+CS4398 USB bei eBay.de: CD Players Recorders (endet 31.03.10 10:00:26 MESZ)
Gigawork 24/192 Up-sampling DAC DA CONVERTER w/ USB kit bei eBay.de: CD Players Recorders (endet 29.03.10 10:00:30 MESZ)
Or that:
Hi End 24/192 DAC DA CONVERTER CS8416+CS8421+CS4398 USB bei eBay.de: CD Players Recorders (endet 31.03.10 10:00:26 MESZ)
Hi Martin,
The Jensen Transformers website has quite a bit of info, maybe too much, but they have many different trafos that can be used. Look through their white papers and application notes for a thoroughly confusing wealth of information.
Almost any dac chip can use trafos but the requirements of voltage out dacs and current out dacs are quite different. Differential V out chips like the 4398 are the easiest to implement. Each output leg has a DC voltage riding on it but there is no potential difference between them, so the trafo is happy as a clam, and can be directly connected to the chip so long as it does not overload the dac chip. When low impedance trafos (600ohm)are used a resistor is inserted in each output leg to limit current flow, anywhere between 250-1kohms can be used. With high impedance trafos, they can be directly connected, but you can run into trouble downstream with impedance matching to the preamp. They are all generally 1/1 ratio as most chips have a plenty high signal output voltage, just not much current, so keeping the cables short is important.
At some point one of the trafo companies will start stocking units for these chips because the ideal impedance is around 2kohms. Some custom 2k trafos have been made that are fabulous but I haven't gotten my hands on any yet.
The current out chips are the exact opposite, they basically want to see a dead short so a trafo with a 50 ohm primary and 1/18 or 1/20 ratio for voltage gain is needed to have a usable signal. That of course depends on the current available, a chip with 4ma out can make more voltage than one with 1ma out.
I'm nowhere near an expert on this stuff and I have oversimplified the explanation. I hope the real experts don't flame me if they read this post.
Oh, something you can do easily with 1543s is stack a couple to increase the output current.
The Gigaworks upsampling DAC board is the one I have personally, but I've repaired a couple others for forum members.
I probably forgot something, but I'm always around.
Best, Bill
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Hi Bill!
Thank you very much, I will do my homework and have a close look on the Jensen-site!
Besides, I'm absolutely convinced that a decent and well chosen OPT is a far better solution than any opamp. But, one thing is the implementation (more difficult than just swapping some opamps), and another one is the price (and the size, too!).
But then, diy is about learning, and I think I will have to learn more about OPTs ;-)
Regards!
Martin
Thank you very much, I will do my homework and have a close look on the Jensen-site!
Besides, I'm absolutely convinced that a decent and well chosen OPT is a far better solution than any opamp. But, one thing is the implementation (more difficult than just swapping some opamps), and another one is the price (and the size, too!).
But then, diy is about learning, and I think I will have to learn more about OPTs ;-)
Regards!
Martin
They aren't as large as you're thinking, but the SuperPro is pretty tiny. You can move the guts into a bigger case if it comes to that. You should be able to find sources for new and used trafos in your country, Studer has made and used zillions of them for their tape decks and consoles over the years.
Best, Bill
Best, Bill
Learning about OPTs should be a basic part of every audio experimenter's toolkit. It's a fundamentally important subject. Hell, transformers are fundamentally important. OPTs are very simple passive devices, much easier to understand than op amps, some of which can be devilishly complex active circuits (not that understanding a black box's internals is germane to understanding what it does in a circuit). And, yes, properly implemented OPTs sound better in an audio circuit than just about any op amps (I'm not about to go on a limb and say this is true for all op amps forever--I'm sure better ones are to come). OPTs are more expensive, sometimes much more expensive: Jensens, Lundahls, and Cinemags--to say nothing of old Altecs--are going to cost ya.
One warning: Don't use a "normal" VOM to measure continuity in a typical mic output transformer. You might very well ruin it by magnetizing it by saturating the core, or even opening it (like a burnt fuse) because the fine wire can't handle the relatively high current. I didn't learn about this danger until recently. I suppose a VTVM with its high impedance might be okay.
I use either implementation, depending on the application--it depends on what parameters are important to me. For this cheap DAC, I'd be hard-pressed to go beyond the usual "musical" op amps. If I were going to be ambitious and (re)build a DAC from the chassis up, I would definitely order a couple of Cinemags (though I've had rather gruff and discourteous service from them--seems they don't value chump change non-OEM customers).
I'm thinking about getting the Super Pro DAC and not bothering with any "upgrades" at all, with the exception of hooking up a 12V gel cell with trickle charge. It seems like a great deal; I get into building phases, but right now I'd rather listen to good music. I've scored a ton of vinyl lately--and my new DL-103 has just started to break in. And I want to listen to some digital too, having gotten some Mercury Living Presence CDs, so this DAC is on the shopping list, so thanks to all of you for contributing to this interesting thread.
One warning: Don't use a "normal" VOM to measure continuity in a typical mic output transformer. You might very well ruin it by magnetizing it by saturating the core, or even opening it (like a burnt fuse) because the fine wire can't handle the relatively high current. I didn't learn about this danger until recently. I suppose a VTVM with its high impedance might be okay.
I use either implementation, depending on the application--it depends on what parameters are important to me. For this cheap DAC, I'd be hard-pressed to go beyond the usual "musical" op amps. If I were going to be ambitious and (re)build a DAC from the chassis up, I would definitely order a couple of Cinemags (though I've had rather gruff and discourteous service from them--seems they don't value chump change non-OEM customers).
I'm thinking about getting the Super Pro DAC and not bothering with any "upgrades" at all, with the exception of hooking up a 12V gel cell with trickle charge. It seems like a great deal; I get into building phases, but right now I'd rather listen to good music. I've scored a ton of vinyl lately--and my new DL-103 has just started to break in. And I want to listen to some digital too, having gotten some Mercury Living Presence CDs, so this DAC is on the shopping list, so thanks to all of you for contributing to this interesting thread.
Interesting stuff, Martin. The output caps in my SuperPro (photo somewhere up the thread may show) are AVX, btw (tantalum, as you say) -- these:
Digi-Key - 478-3936-2-ND (Manufacturer - TAJD476K020RNJ)
Still toying with the idea of dropping in some Nichicon Muse ES (nonpolar) 47uF that I have, maybe with polypro bypass.
I did upgrade the power-supply cap, to 390uF/35V, I think. Panasonic FC (sorry, Martin). Worthwhile, but not at all a major difference. That board is hard to work with (tiny eyelets, and for the cap, there are eyelets on both sides of board).
Okay, I'm listening to my Pro DAC707 right now, Monday night, after ordering it on Friday from Cryo-parts. That's some fast service! Listened for an hour or two using the stock 12V, 4A p.s., then got antsy and rigged up my 12V battery. Very satisfying. I might open it up and swap out some caps in the future, but I'm not inclined to do anything to this tiny music maker for a good long while. Dunno if it sounds any better than the Beresford TC-7520 that I burned up recently, but then my long-term audio memory ain't all that great. Definitely not fatiguing or annoying. . . .
Let it burn in for quite a while with the stock power supply to get used to the sound. Then switch over to the battery. Only this way you will get an idea of what kind of improvement this makes!
I would normally try what you suggest, but I'm not interested in that right now. I just want to listen to music! There is no doubt it sounds better battery powered.
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