I suppose this whole issue is really over semantics... but I really don't want to get into a discussion on the written word and how best to interpret it. I believe a lot of latitude has to be given on a forum and sometimes thing just don't come out correctly, or clearly.
'Or you can do what people do there: use to single OPA827 on a Browndog adapter.'
It's easy to interpret this phrase as a 'recommendation'. Or, you could simply believe it's a statement of what other people do here - as carl stated. A recommendation in an indirect way - and without expressly using the phrase, "I recommend you use this opamp..." I'll cut carl some slack here. I better understand the context now.
It's hard enough to sort out the real nuggets of fact in a thread, when everyone has their own, favorite pet, op-amp, chip-amp, discrete transistor flavor, capacitor and the list goes. So, the less educated have to sift through everything, and often ask dumb questions in the process to get to the truth - or should I say facts! Truth is one thing, facts are another.
Let's put this little flare-up behind us and move on with a list of progressive mods that make a 'real' difference in the sonic performance of this DAC - not just a nuance of more bass, soundstage integrity, or trying to squeeze another .001 unit from the distortion analyzer. When I say, 'a list of progressive mods...' I mean specifics, not generalities. Capacitor values for instance, brand names perhaps, which exact ones on the schematic to change, etc. I think you get my point.
'Or you can do what people do there: use to single OPA827 on a Browndog adapter.'
It's easy to interpret this phrase as a 'recommendation'. Or, you could simply believe it's a statement of what other people do here - as carl stated. A recommendation in an indirect way - and without expressly using the phrase, "I recommend you use this opamp..." I'll cut carl some slack here. I better understand the context now.
It's hard enough to sort out the real nuggets of fact in a thread, when everyone has their own, favorite pet, op-amp, chip-amp, discrete transistor flavor, capacitor and the list goes. So, the less educated have to sift through everything, and often ask dumb questions in the process to get to the truth - or should I say facts! Truth is one thing, facts are another.
Let's put this little flare-up behind us and move on with a list of progressive mods that make a 'real' difference in the sonic performance of this DAC - not just a nuance of more bass, soundstage integrity, or trying to squeeze another .001 unit from the distortion analyzer.
When I say, 'a list of progressive mods...' I mean specifics, not generalities. Capacitor values for instance, brand names perhaps, which exact ones on the schematic to change, etc. I think you get my point.
thanks,
nah it was the series of posts, as you say the first one by itself could have been seen as just saying that is what some people do here. then you did misunderstand, not could have but did and he did nothing to indicate that he actually meant AD827 in his next post, quite the contrary he mentioned OPA827 again and said that the price goes up as the quality goes up, which would indicate that he was saying it was worth the money and this is where I took issue, as i dont think at this stage of the build it is worth the money or wise and i see this type of recommendation on here regularly and I think its irresponsible.
I think he was actually using the price for AD827 on browndogs too, but wrote OPA827 again because it was in his head then and you had said opa827 too; because finding 3 x dual opa827 browndogs for that money would be nice to say the least. He was suggesting premounted soic8 adapters also, so i'll use a price from their site; a dual type browndog with dual OPA827 premounted is $36 at the browndog site and more elsewhere, so thats $108; the chips alone are $15 each at mouser.
but I didnt do that detective work at the time, just thought he must have a cheap source on ebay perhaps.
so to your question
so to your enquiry, although there are some guides that give such definite recommendations and perhaps even give percentage of improvement, I find these type of guides a bit silly, they dont take the synergy with other gear in the chain or personal taste into account and ones of that type are very unlikely (read almost never) to give you the quantitative measurements you desire. If you wanted such a walk through then you should have bought one of the ebay boards that has a very big thread with a guide, but then again measurements are unlikely.
i'm afraid this is where you have to pick up the ball and run with it yourself, or be happy with it how it is, which is also a perfectly reasonable option, sounds like you enjoy it already and it looks great.
We haved already mentioned the areas to look at, start with cheaper parts LIKE the AD827, OR OPA1642 and beef up the bypass caps (connects from each opamp +/- power pin->ground, read the opamp datasheet and/or schematic) at the power supply pins on the adapters, solder directly to or as close as possible to the pins if you can, a 100uf nichicon FP type polymer cap and a 0.1uf panasonic pps film, vishay polypropylene film or Kemet gold NP0 ceramic perhaps. beef up the main supply caps and then i would start looking at how the power supply and grounding is handled on this board and make sure the analogue parts of the dac output stage and the dac itself are separated from the digital section and have their own return to ground. these are the first 2 things that should imo be looked at and will give best bang for buck also.
i'm not going to do up a step by step guide just by looking at the schematic and i doubt anyone will, if the information doesnt already exist somewhere i'm afraid you will have to take some steps yourself to find what works for you. sounds a bit like you want to skip the diy part and thats ok, but you should make your purchase to suit.
good luck!
nah it was the series of posts, as you say the first one by itself could have been seen as just saying that is what some people do here. then you did misunderstand, not could have but did and he did nothing to indicate that he actually meant AD827 in his next post, quite the contrary he mentioned OPA827 again and said that the price goes up as the quality goes up, which would indicate that he was saying it was worth the money and this is where I took issue, as i dont think at this stage of the build it is worth the money or wise and i see this type of recommendation on here regularly and I think its irresponsible.
I think he was actually using the price for AD827 on browndogs too, but wrote OPA827 again because it was in his head then and you had said opa827 too; because finding 3 x dual opa827 browndogs for that money would be nice to say the least. He was suggesting premounted soic8 adapters also, so i'll use a price from their site; a dual type browndog with dual OPA827 premounted is $36 at the browndog site and more elsewhere, so thats $108; the chips alone are $15 each at mouser.
but I didnt do that detective work at the time, just thought he must have a cheap source on ebay perhaps.
so to your question
so to your enquiry, although there are some guides that give such definite recommendations and perhaps even give percentage of improvement, I find these type of guides a bit silly, they dont take the synergy with other gear in the chain or personal taste into account and ones of that type are very unlikely (read almost never) to give you the quantitative measurements you desire. If you wanted such a walk through then you should have bought one of the ebay boards that has a very big thread with a guide, but then again measurements are unlikely.
i'm afraid this is where you have to pick up the ball and run with it yourself, or be happy with it how it is, which is also a perfectly reasonable option, sounds like you enjoy it already and it looks great.
We haved already mentioned the areas to look at, start with cheaper parts LIKE the AD827, OR OPA1642 and beef up the bypass caps (connects from each opamp +/- power pin->ground, read the opamp datasheet and/or schematic) at the power supply pins on the adapters, solder directly to or as close as possible to the pins if you can, a 100uf nichicon FP type polymer cap and a 0.1uf panasonic pps film, vishay polypropylene film or Kemet gold NP0 ceramic perhaps. beef up the main supply caps and then i would start looking at how the power supply and grounding is handled on this board and make sure the analogue parts of the dac output stage and the dac itself are separated from the digital section and have their own return to ground. these are the first 2 things that should imo be looked at and will give best bang for buck also.
i'm not going to do up a step by step guide just by looking at the schematic and i doubt anyone will, if the information doesnt already exist somewhere i'm afraid you will have to take some steps yourself to find what works for you. sounds a bit like you want to skip the diy part and thats ok, but you should make your purchase to suit.
good luck!
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To the contrary... I expect that those DIY'ers making improvements are doing so with some basis in fact, not a feeling about what may sound better. No one can make improvements based on 'other gear in the chain', because they don't know what other people have or even like! What I do expect - perhaps unwittingly so - is for the EE's in the community to look at the overall topology of the circuit and with their understanding where sonic improvements could be made, make recommendations of component replacements to affect that positive change. Is that really asking too much?
I'm not asking for a step-by step guide, just a bit more detail on where the improvements can be made and the reason for doing so. What you provided in your next to last paragraph was perfect - although you gave no reason as to why and what improvements can be expected - whether quantitatively or subjectively.
I may never embark on making the types or series of mods to boards often discussed within these threads. I get the fact that many people do and have no problem with that. I'm here to learn and threads like this help to enlighten me to the possibilities of improvements. All I was driving for was some degree of substantiation as to why the mod would help and why.
I can easily make the physical changes to components, solder, cut traces, etc., but I don't want to get caught up in redesigning a circuit (I'm totally unqualified for that!), or otherwise bastardizing a PCB for a limited amount of improvement. Perhaps my level of DIY'ing is different - and that's ok, as you say. I still value your input.
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hi redjr, AD1955? last year's diy DAC blind test that I've participated, AD1955 won beating AD1865, TDA1541S1, TDA1543, PCM63, ESS, AKM's etc with various output stages. I've asked the owner what op amp used, it was LM4562 can casing, US made ones, not Malaysian. Hope this helps.
btw, please visit my blog just sharing my dac toys
btw, please visit my blog just sharing my dac toys
Thanks. I'll look into the LM4562. Do you know off hand how compatible it is with the OP275? Drop-in replacement? Circuit topology may come into play here is as well using that chip.
I'd like to tell you that your comments on this AD1955 DAC, along with my interest in having a USB capable box, made me curious enough to find out more about it.
It seems I may order a package similar to yours: DAC + box + transformer (R-core in my case). It will be a different vendor, but only two seem to sell it on eBay.
It should take some time to get here, but it will be interesting to compare it with my AK4396.
I would have preferred it in kit form, but it's only sold assembled.
Thanks!
It seems I may order a package similar to yours: DAC + box + transformer (R-core in my case). It will be a different vendor, but only two seem to sell it on eBay.
It should take some time to get here, but it will be interesting to compare it with my AK4396.
I would have preferred it in kit form, but it's only sold assembled.
Thanks!
Thanks syklab. According to the datasheet it also comes in DIP-8, so would work nicely. I may give it a go based on ide2003's comments.
carl - I would have preferred a full 'kit' from the seller too, but as it turned out I pieced together the same 3 'modules' he ultimately suggested for what I was after. Yes, it would have been better to get the PCB as a kit, because it would have allowed for upgrading passive components as well. Not sure I would have gone that route to start with, but at least it would have been an option. I enjoy soldering PCBs, and I'm rather fastidious about it too.
I'll double check a couple of the sellers I like on eBay. Many times - even on assembled only items - further down in the description they state you can get it as a kit, just by asking. They're usually a few buck cheaper too.
I guess it's a moot now if you've already ordered your stuff. carl - Here's a different board in kit form and does support USB - using the AD1955 DAC. Appears the op amps are on Browndog adapters and socketed making swapping them out easy.
I've ordered something else from this seller (zoe_tsang), but it has not arrived yet. Unfortunately it was not something I needed right away, so it's literally on the slow boat from China! I think I can expect it in about 15 days or so.
I've ordered something else from this seller (zoe_tsang), but it has not arrived yet. Unfortunately it was not something I needed right away, so it's literally on the slow boat from China!
I think I can expect it in about 15 days or so.
Hi redjr, like it or not there are differences in sound of LM4562, depends on its package, best is US can, some reports 100hrs break in time.
Hi,
You are most likely right but the US made T05 type is so much more expensive than the Dip8, even the Malaysia made T05 is already 25US$ each which is 5 times the Dip8. Element14 carry few of them.
I have tried the following during the last few days:
LM4562NA/NOPB
LME49860NA
OPA2134PA
OPA2132PA
OP275
I feel that 4562 is the best and followed by49860. I only try one opamp at the last stage, don't know if it is call a buffer stage or addition stage. If I have to spend 25US$ for one single 4562, I would rather try a 6922 tube buffer stage.
Thanks, I also found that same AD1955+WM8805 kit. But that one is ONLY sold as kit, and there are plenty of SMD parts that come unsoldered. Not something I want to.
That is the seller I ended up buying a kit similar to yours, with even a better price than the other seller. Bought board + transformer + case.
Unfortunately he quoted a very high price for the AD827s that I also wanted to try, so I got them from a different vendor.
Now everything is (literally) on a slow boat from China, particularly because of Brazilian customs that are working slowlier for things coming from there.
Carlos
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I like you build syklab. Looks neat and clean. I think I'm going to order some 4562HA (CAN) and put them in some Browndog adapters. BTW, Newark has them on promo for $16 each. I may consider beefing up the e-caps too.
The 4 PS Caps were changed to PANASONIC - ECA1VAM472X 4700UF, 35V
The 2 E CAPs on the analog side were Panasonic 2200uF 16V
The 2 caps before the 4562 are Elna Tonerex 47uF 50V
The next thing will be those decoupling caps around the op amp.
Your upgrades seem interesting, particularly using an external block to screw the terminals to.
But after seeing the circuit the vendor send to me, same as the uploaded here on another page, there are a few changes I will perform:
1) If you are adding external stuff, I would recommend splitting the capacitance (or double it) adding a series resistor in between. That is adding CRC filtering before the regulator. That would mean unsoldering the diodes on the pcb and putting them before the first capacitor on the CRC. That should help the regulator deal with the ripple. I will design a pcb to hold it all and fit in the available space.
2) Change the LM 317/337 adj bypass capacitor. This is very important. IMHO the designer did the opposite of what should be done. They put a larger (too large) capacitor at the output and a small (too small) capacitor to bypass the adj leg. Check these measurements carried done in TNT-Audio:
Simple Voltage Regulators Part 2: Output Impedance
Best value for adj cap seems to be 220uF. That's what I will put on mine.
OTOS, the output capacitors (1000uF) has already been recommended on this Forum to be a similar value (220uF) BUT... preferably not being a low-esr type. If you are going to use one, you should add a 0R5 resistor in series with cap.
Unfortunately that can't be implemented on the external board I'm planning, so it will require some unsoldering.
The original diodes, if you prefer to, can be left where they are and just solder the wires from the external pcb to the existing cap terminals. More details on this when the time comes.
Even if currents are quite low, one thing I will check is the LM317/337 dissipation. You should check if they run just warm.
Carlos
Carlos - Just a heads up. Many of the DAC kits I looked at from the China sellers already had the SMDs soldered on. I'm not ready to tackle SMDs just yet either, that's why I looked. Be sure to check-out all the pictures of the PCB shown in their listings. You will note many have the SMD already mounted even though it's a kit, so that's a plus! I'm not saying the kit you ordered did though. Do you have a link to the one your bought?
Yes, I'm aware many of China's kits already have the SMD parts soldered on. I bought my AK4396 kit like that, with no other parts.
This time I tried to get the parts, even if I didn't use them, but this kit is solely sold assembled.
The link for my kit is this DDIR9001 + AD1955 + PCM2704 DAC decoders G-2 | eBay.
Got the R-core transformer, not the toroidal one.
For a start I will perform those supply mods I mentioned above, with an external raw-supply board. Also I'm looking for a digital transformer for the S/PDIF input, and I got the AD827s to try on the output.
Carlos
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