Looking for Better Jitter Reduction in a DAC
A couple updates for all you kind gentlemen regarding my quest for better SQ from my digital. I’m now using shielded cables from the DAC and PWT into my Brickwall (which uses ferrite filtering), plus some PS Audio Noise Harvesters and the results are positive. With the HDMI (Cardas cable), sound is closer to "analogue." With SPDIF (Oyaide coax), the music explodes thru my speakers with increased dynamics, detail, and a huge soundstage, not to mention a lower noise floor. But, the sonics are still clearly from a digital source. I still believe my DAC lacks a high quality clock, so before I upgrade the DAC, I might give the Uptone SPDIF ISO Regen a try. @dlcockrum , I saw your negative review of the ISO Regen as used in your system. It could be that the clock in your Exogal Comet is so good, you don’t need an external timing device. Also using a Purist Audio USB from the Aurender may already have excellent synergy. As a side note, if anybody knows about the PSA Noise Harvester, the LED's are constantly flashing indicating that they are detecting and filtering noise entering the power conditioner. |
Hi lowrider, I just wrote about my impressions in my system and to my ears. That was how it fell. As you say, I suspect that a big part of my results were due to the excellent noise/isolation/jitter characteristics of thr Aurender/Exogal combo and the cables I use and intended to convey that in latter part of the writing. Sorry if it did not read that way. There are many positive impressions of the Uptone products held by others in their systems and to their ears and I hope to hear from them as rebuttal posts to that thread. I expect that the Uptone gear is as good as any out there for applications that benefit from their effect. Dave |
Dave, I believe the clocking performed by the FGPA in the Exogal makes a reclocker unnecessary. But, everyone of us would have still tried for that extra bit of perfection. I'll bet the Purist cable also is excellent. I have all Purist analogue cables and they are an integral part of my modest system. |
That was the posit from Jeff Haagenstad of Exogal when I solicited his opinion before trying the ISO Regen and I expect you are both right, lowrider. I gave it an honest shot which is, it seems, more than many often do before judging here in writing. The Purist 30th USB cable has ferrite filters around the 5v power lead (but not the signal conductors) and that, along with the Comet's prowess in that area, may have contributed to the lack of improvement from the ISO Regen’s galvanic isolation. The takeaway for me was that I never expected that the sound quality would lessen, only perhaps that it would not change audibly. But it did in my system to my ears and I felt that to be noteworthy. Dave |
http://https//www.head-fi.org/threads/gustard-x20pro-dac-es9028pro.824593/page-3 Hmmmmmm. You might risk being a Guinea Pig... Did you make an offer on the Comet for sale here on Agon? Dave |
Thanks for the info, Chris. I'm sure an external LPS makes all the difference. Dave, I've read user reviews of the Gustard X20 Pro and it seems the way to go is with the modded unit. Ric Schultz is charging about $400, which still makes it very affordable. But I don't want to be a Guinea Pig; I wonder who would service it after modding. That Comet SE looks positively "dreamy." But I don't have enough cash on hand, I'm still in the $1200 range. That's why I'm interested in the iFi. I'm thinking that if I go cheap right now with the reclocker, I could save for a major upgrade down the road. Thanks, Jim |
Offer $1200 and see...remember, no gadgets required for the Comet. Excellent power supply included too with that Plus model for sale. I have spoken with Ric in the past and I am not worried about his end, but very much so the firmware issues from the Gustard factory in China. You may not yet realize how maddening this type of thing can be. Ric was also modding the LKS DAC the last time we spoke. Another risky purchase IMO but may sound glorious. Alas, The LPS-1 would not work with my modem/router (the only place in my current system where it could improve on the existing external power supply). I am listening to the decent switching P/S, included with the LPS-1 as an "energizer", powering my router modem. Haven’t yet tried a sound quality comparison between it and the wall wart that came with the modem/router. Dave |
I'm quite interested in what the LPS-1 does for your system. The LPS-1 is a definite improvement over the iPower supplied with the SPDIF Purifier. Bass is fuller, tighter and extended. Highs are extended and clean, not searing! Voices are natural and full. With the iPower there was a slight graininess to the sound. With the LPS-1 all graininess is gone and the background is blacker than ever. Nuances are easier heard, instruments are better separated and natural. Dynamics are improved and imaging is off the charts. I was very surprised at the results. With all of the iPower literature and hype I thought it would be a dead race but the LPS-1 proved to be a very worthy addition. My thoughts are the SPDIF Purifier is the last device to "work" on the signal before the DAC. Part of what it does is to clean up re-clock, and pass the signal galvanic-ally isolated. The digital signal is so fragile that any negative electrical abnormality will interfere. The LPS-1 offers a clean and pure power source so the SPDIF Purifier can perform at its best! At the cost of less than a power cord, pair of IC's, speaker cable, esoteric tweeks, and tubes, the LPS-1 is a a very solid addition/investment/ recommendation to any low DC powered component. Only drawback is that your limited to 3.5,5, and 7v. Hope that Uptone will make a larger version for 12v DC and higher gear someday. Chris |
I bought one of these and am very impressed with the build quality, finish, and overall heft of this power supply for 12V 3.5a : http://www.ebay.com/itm/Accubasston-Steady-Linear-Power-Supply-12V-15V-24V-DAC-Phono-Head-Amp-Steamer/172861338756?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 Dave |
Great idea, @dskinner. I went direct from DAC to amp and the sound is very pleasant. Still sounds like music is from a digital source, but nothing offensive at all. In fact, the amp is warm with nice tube bloom but is lacking the deep imaging that the preamp provides. Could the output of the DAC be overdriving the preamp? I have a single-ended system with a push-pull tube amp and an Atma-Sphere UV-1 pre. The DAC outputs 2.8V RMS (unbalanced). I will tube-roll the 6SN7's in the preamp and see if that is the cause of the harshness. My gut says no because I'm using 1950's RCA Blackplates. |
Dave, it looks like that LPS is one of a kind. Using Google, I haven't seen any others. I contacted Steve Nugent about a Synchromesh purchase and he recommended trying a few things first. He believes that so called "digital" power cables using filters can increase jitter. So I sent the JPS digital cable back and now I'm using quality shielded cables on my digital. I also bought a new 1.5m S/PDIF cable and a Lifatec Toslink. I had a financial setback due to some medical bills which makes it impossible to buy a new DAC at this time. I could afford the Mytek Stereo 192-DSD-DAC, which gets great reviews, but is 5 years old and does not have a Femto clock like the Brooklyn. So my next move is to give the iFi iPurifier a try and see if my preamp is causing problems. |
Hi lowrider, Very sorry to read of your medical situation and I understand that completely. I cannot speak to the JPS power cord from personal experience, but I do not see anything about it or any other quality power cord that could increase jitter. A cleaner AC feed can do nothing but good for a digital front end and should keep digital hash from returning to the AC source for the analog playback chain. Let your ears be your guide. Dave |
Yes I agree with Dave letting your ears lead you. The iPurifier will take about 100-200 hours to reach its full potential. Music Direct has a 60 day return policy so you should be good with respect to burn in. Going through some medical expences for the last couple of years too. It’s a b---- but part of life. Hope all goes well for you in that regard. Chris |
Dave and Chris, many thanks for the good wishes. My review of the JPS AC-X... Extremely effective and affordable as an all in one filter/conditioner power cord. In my case, I did not need such powerful filtering since I have dedicated lines and 2 upstream power conditioners. Even with the AC-X plugged directly into the wall from the DAC, the soundstage was compressed compared to my other PC’s. Using a shielded cable into a Brickwall provided the best results. The issue may be that my DAC doesn’t bleed any noticable noise back to the mains, plus I already have a very a very low noise-floor. Anyway, my digital harshness doesn't seem to be power related. I would recommend trying this cable in a system w/o clean power. BTW, the cable was burned-in by running an air conditioner thru it via an adapter for one week. |
Good feedback lowrider. I believe your results. Much better reason IMO than the advice of someone else. Can't say whether it was due to being a "digital" PC or not as I have had similar findings with some PCs that were not. I really hope that you are able to get the DAC of your choice eventually. Until then, I recommend you try the free samples of the Mad Scientist's Black Discus at various locations in your system to see if they help with the harshness. Dave |
It is quite easy to go down the garden path with digital. There are a lot of variables, even when using a transport, including jitter, digital filtering in the DAC and DAC output stage and power system. Any of these can make it sound "digital". The best way I have found to approach this challenge is to focus on one thing at a time and optimize it, eliminating that effect as a cause. The first thing is to eliminate jitter. Trying to do this by selecting a particular DAC just confuses things. Most DACs with resampling in them change the jitter and thereby the sound, but never never eliminate jitter, or even reduce it to inaudible levels. The source must be optimized in order to do this, whether its a transport, USB converter, server, computer or network renderer. With most transports, the best solution is a reclocker, unless you are willing to spend $20K for a transport, which is IMO ridiculous. Optimizing the DAC digital filter is harder. There are several approaches: 1) DAC that has discrete D/A implementation and custom filters 2) NOS or ladder DAC that has NO digital filtering 3) DAC that has selectable filters Optimizing your choice in output stage has several options: 1) tube output stage 2) discrete transistor output stage 3) minimum # of op-amps in the output stage 4) active output stage with feedback that linearizes the behavior Optimizing the DAC power system is much harder. With some DACs that have external power supplies, you can upgrade and improve this. Adding an AC voltage regulator like the Plasmatron from VHaudio.com helps a lot, but not inexpensive. IMO, trying to use cables or filtering to make it sound more analog is the wrong garden path. It ultimately sacrifices dynamics and detail. Steve N. Empirical Audio |
I appreciate your comments, @audioengr . I contacted you recently regarding a Synchromesh purchase and appreciate your no-pressure-to-buy attitude. I'm following your advice and focusing on each element one at a time. First, I addressed the power delivery and chose a good quality shielded cable as suggested, rather than the cable which uses ferrite filters. As for my source, I'm concentrating on Redbook playback first and am using a PSA Perfectwave Memory transport. This unit outputs a signal which has been reclocked from a buffer and not from the spinning CD. I actually don't hear much difference in sound quality between the HDMI (I2I) signal and the optical or 75 ohm coax. I'm now using a 1.5m BNC coax which presents deeper imaging and more low-end extension than the other formats. I took the advice to remove the preamp from the chain, and the result is a much smoother presentation without harshness. I believe the DAC's output of 2.8V RMS is overdriving the unbalanced inputs of the preamp. In any event, the sonics from a DAC-direct hookup is still not what I would call "analogue-like." |
If the jitter is truly low from the transport, then the problem is likely the DAC. If the DAC does not have a good volume control technology in it, this could be the problem too. Perhaps not that much better than the preamp, just different. I want you to try modifying the CD disks themselves. This will lower jitter even more. There are several steps you can take: 1) get a really good treatment solution from Jena Labs and treat the disks. Spray it on and then rub with a lint-free cloth outwards. I believe they provide the cloth. 2) try putting the disk under a fluorescent light, up close for 20 seconds before you load it 3) use a degausser, like those used to erase the older cassettes on the top of the disk - this removes charge 4) the best treatment is actually to put a rubbery coating on the top of the disk, avoiding the center where it is chucked Another thing you can do is rip the CD and then rewrite it to a Mitsui Gold audio master blank disk, after treating the blank disk. It's actually must simpler just to rip the disk and then play it back using a computer audio solution, like USB or Ethernet. I also makes your entire library more convenient and you don't have to listen to tracks that you don't like. Jitter will be much lower than any transport too. Steve N. Empirical Audio |
Looking forward to reading your results from this advice lowrider. I have all of.these tweaks (Jena labs CD polish, AVM, Acoustic Revive CD degausser) from years of trying nonsense and would be glad to loan them to you as I found them to be a complete waste of time and money. You already have a great transport that buffers and reclocks so none of this makes any sense excepting a better DAC which I suspect to be Steve's endgame anyway. He does make a good one. Best of luck to you lowrider. Dave |
I bought this plastic spray from Home Depot and put a shield over the disks I made from thin card stock to protect the center hub. This rubbery coating makes a BIG difference. You used to be able to buy rings made of similar material and glue them to the disk. The other things make a small difference, but audible if you have a resolving enough system. Steve N. Empirical Audio |
@audioengr , thanks for your interest and advice, Steve. The PS Audio transport gets high marks for jitter control from users online. My PSA DAC is their budget model which uses ESS Sabre chips (no detailed info available), and does not use a FPGA device like their other DAC’s. So, I think there may still be some value to trying a reclocking unit. It does use passive filtering and casts a 3D soundstage with excellent dynamics. The superb sonic characteristics is why I’m trying to make it work in my system. As for as computer audio, I do have a Mac with CD rips and downloads, but currently it is not running certain apps like music players. There are some system extension errors and I need to get it serviced. FYI, I still enjoy collecting CD’s and vinyl, especially imports. And I am an obsessive collector :-) I will attempt to treat some CD’s; it’s interesting that you believe a disk can hold a magnetic charge. I think that the plastic coating may be capable of holding a static charge. Many thanks, Jim |
I used to mod DACs, about 20 different ones. They all had strengths and weaknesses and many had poor design features that were obviously copied from another manufacturer that knew little about it too, even Sony did this. The most common thing I found was insufficient power decoupling for the D/A chips and the op-amps. Another thing I found was ground-planes that were broken-up, sliced and diced by traces, causing crazy current return paths. Another is too many op-amps in series. These things usually lead to an un-dynamic sound and a thinness, even harshness. This is the deficiency with most preamps and amps too. Another typical thing they do is put a 50 ohm BNC for the 75 ohm S/PDIF input connector. Duh!! Steve N. Empirical Audio |
Steve, interesting stuff about some DAC designs. This problem I'm having makes me keep thinking about grounding issues due to the harsh sound. As far as outside the components, there are no grounding issues; I've tried different IC's (single-ended system), changed PC's, and checked for broken grounds and ground potential with a meter. What is very curious about all this is that the I2I signal doesn't sound any better than the other connections; the ground and data travel separately in I2I. The reason I purchased an optical cable was to test it against grounded connections. Now I'm wondering about the quality of the output from the transport. It is a refurbished unit with warranty and I did send it back to PS Audio for a transport upgrade and I have tried 2 different versions of firmware. Maybe borrowing a DAC is the only way for me to perform a proper test. |
Ground-loops don't generally cause harshness, only HF background noise. Some reclockers provide galvanic isolation, so eliminates ground-loop. Cables make a big difference and you should be using the best I2S or the best S/PDIF you can get, without breaking the bank. The problem with virtually ALL transports is that the S/PDIF output signal has a fairly long risetime. This makes it jitter-prone at the receiving DAC, and makes the requirement of at least a 1.5m long cable. Faster risetime from a computer converter or a reclocker will reduce added jitter, but requires a really good impedance match at driver and receiver and the cable. Steve N. Empirical Audio |
Try this... https://www.mutec-net.com/product_mc-12.php https://www.mutec-net.com/product_mc-3-plus-usb.php These unholy units interconnect anything to everything and have super clocking systems. I know you say USB is secondary, but these system's drivers ensure bit-for-bit transfer through Windows kernel. I have the 1.2 on order..... I am connecting an Accuphase DP55v CD player with digital ins to my computer (Foobar, bit-for-bit library from a home server). I contacted Accuphase a long time ago and they noted their unit does not re-clock the incoming signal so I need one of these. Long history.... I used an Audio Alchemy DTI Pro 32 for computer to DAC interface but these new Mutec units are far superior in their jitter is lower, connect more things, and pass more sampling rates. The unit has plenty of in/out options.... It looks like I can use it to A/B tons of grear as a side benefit. Peace Bruce in Philly |
Bruce, the 1.2 looks like a great unit and it's affordable. The reason I said USB is not a priority is due to the fact that my Mac has some bugs in it and is not running any music player software. It will go into the shop soon. Plus, I would like to get CD running smoothly since I just bought the PSA Perfectwave. |
Actually, I just purchased the 1.2 from eBay for $190. A great deal IMO. If anyone cares, I have a few moments to type..... I had an old laptop running Windows XP as my player. This PC sat in my equipment rack and was a real challenge to get bit-for-bit out of it... XP was not that sophisticated and I had to remove some of Microxoft’s kernal programs... anywho.... I took the SPDIF out to an M-Audio converter to optical... then to the Audio Alchemy, then to my Accuphase (Accuphase has both optical and RCA ins). Foobar’s kernal streaming driver worked well. Since the Accuphase is both a DAC and player, I could put a CD in the tray and A/B the exact same bit stream from my computer...... I got it 99% there.... jitter was a big problem so I understand your real needs. Then I dumped that whole rig and purchased a Benchmark DAC1 with native USB port and one that touted no jitter. Life got way easier. I was using a pair VTL 300 Deluxe tube monoblock amplifiers and one just died... so I just received my new PrimaLuna HP intetgrated amp.... I chose an integrated so I could hook up more than one source..... so now I could pull out my Accuphase and A/B with the Benchmark... and hook up some old stuff like a tuner etc... Now I am back to using that Accuphase... it just sounded so much better than that dead sounding Benchmark.... I dumped the Audio Alchemy but could never part with that wonderful Accuphase... now I need something back again with native USB interface with Windows 10 hence the MUTEC (temporarily, I am using the M-Audio Transit product that I will retire.) An interesting lesson here...... the Benchmark DAC 1 was generations ahead of the Accuphase but it didn’t sound as good. The lesson here is that just because there are newer chips out there does not mean the old stuff sounds worse...... as we old guys know, it is all in the details of implementations and the subtly of designs. The Accuphase used four stereo DACs in some goofy configuration that sounds beautiful.... I have no idea what they were doing but they did it right. There is more to this story (more like a journey), so some of the equip configurations above may not make sense... lotsa stuff came in and out over the years, but I thought I would share the highlights. Peace Bruce in Philly |
Bruce - often older D/A chips sound more musical because of the limited digital filtering and ladder-DACs used etc.. I used to sell a tubeDAC called the Spoiler with ladder DAC in it. Very musical The problem with them is that they don't render the HF transients very well and they don't support hi-res. Need a newer D/A technology for this. To get the beauty of the older chips and the speed of the newer chips in the same design, it requires a really good designer and implementation, including excellent power delivery. PD includes power supply, wiring, ground-plane correctness, regulation and decoupling. All of these are critical, particularly with D/A chips. Very few designers have a good grip on all of these aspects. Steve N. Empirical Audio |
Interesting....... I plan on dragging that older Accuphase to a good store and comparing it to some of these modern units.... I am rooting for the Accuphase simply because it sounds so much better than a Class A rated DAC, the Benchmark DAC1. Again, the design of the Accuphase is that it uses multiple stereo DACs..... who knows, maybe these guys discovered something great. From their manual: "The MDS (Multiple DeltaSigma) principle em-ploys several deltasigma type convertersin a parallel configura-tion which results in adrastic precision enhancement. The delta sigmaprinciple combines oversampling with noise-shaping (a kind of digital feedback) which projects the amplitude information of the digital signal onto a time axis for precise conversion.Figure 1 shows several delta sigma converters which are fed with the same signal and whose outputs are combined to arrive at the overall waveform. " Sounds good to me. Peace Bruce in Philly |
I find it very odd that SPDIF coax, i2i, and optical from transport to DAC all sound the same. I’m using the highly rated Lifatec glass optical cable and an Empirical Design 1.5m coax. I’m starting to wonder if the problem is the output of the DAC. I'm using the unbalanced output from a fully-balanced DAC. Preamp and amp are both SE. DAC output is 2.8V RMS (unbalanced). |
@bruce_philly How old is the DAC1 you are comparing to the Accuphase? That DAC1 runs pretty hot. I think it might need a recap after 10 years possibly due to the internal heat causing aging of the caps. You should be comparing to the DAC3 these days. The DAC3 uses 512 delta sigma DACs over several ESS Sabre 9028 chips. Basically this design is a hybrid between a ladder R2R and a single delta sigma 1 bit DAC. This type Sabre chip is where performance minded DAC conversion is heading - the best of both worlds - high linearity (from 1 bit delta sigma) and low noise (of ladder style design) - achieving 9 bit resolution and extremely low noise a far cry from old single 1 bit sigma delta methods of the 90’s. |
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@shadorne , I'm now wondering about the SQ of the output stage. I don't think it's a matter of taste, it's more that the DAC produces the typical digital artifacts we expect to be corrected. There are so many positive reviews, both pro and user, that state how smooth this DAC can sound when fed a quality stream such as from another PS Audio device. I've even been on the PSA forum regarding my issue. There is a passive analogue output filter in the design, but as Steve N. has pointed out... There are a lot of variables, even when using a transport, including jitter, digital filtering in the DAC and DAC output stage and power system. Any of these can make it sound "digital". I have taken the advice from the PS Audio forum and installed a PSA power cord and am using a Blue Circle passive conditioner. Noise floor is so quiet and soundstage is wide and deep. As per Steve's advice, I stopped using ferrite filtering in my power conditioning. For analogue output, I have changed IC's and PC's, checked for open grounds with a meter, and now I'm going direct from DAC into Amp. But I still wonder if the high output voltage could be the cause (specific to my system). I have reached out to The Cable Company regarding a DAC from their lending library. They only have a PS Audio and a Chord Hugo available. |
