AudioCircle
Industry Circles => Empirical Audio => Topic started by: audioengr on 15 Jun 2011, 08:05 pm
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For those that don't subscribe to TAS, the review of the Peachtree iDAC in the July/August issue is very interesting.
http://www.avguide.com/review/peachtree-audio-idac-tas-214 (http://www.avguide.com/review/peachtree-audio-idac-tas-214)
Steven Stone concludes that the digital source is actually more important than the DAC itself. When the iDAC and the W4S DAC's were driven with his Off-Ramp 4, not only did they each sound a lot better, they sounded almost identical. No surprise to me :thumb:
This is all the more reason to invest in a really good digital source, with the best clock you can get. Anyone know where to get one of those? :wink:
Steve N.
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Congratulations, Steve. I think you're quite right about the importance of clocking. It is, after all, the essential aspect of digital signal transfer fidelity. What else does digital fidelity concern?
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Hi Steve,
At some point I was thinking about getting a miniDSP 4x8 since I actively tri-amp my speakers. Do you think the off-ramp would be a good fit with something like that?
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Congratulations, Steve. I think you're quite right about the importance of clocking. It is, after all, the essential aspect of digital signal transfer fidelity. What else does digital fidelity concern?
I put analog distortion from compression as #2. Eliminating the preamp improves this.
Other principal digital things that affect fidelity are:
1) digital filtering - use it sparingly or not at all
2) D/A conversion technique - affects resolution and S/N ratio - use modern D/A chips, but avoid switched-capacitor techniques
3) digital cable - make sure it's 1.5m long and low-loss
Steve N.
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Hi Steve,
At some point I was thinking about getting a miniDSP 4x8 since I actively tri-amp my speakers. Do you think the off-ramp would be a good fit with something like that?
The Off-Ramp provides a low-jitter digital source for any system. What is a miniDSP?
If it's like a DEQX, then this will work well. A number of my customers use the Off-Ramp to drive DEQX.
Steve N.
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Details here - http://www.minidsp.com/onlinestore/detail/7-minidsp-kits/flypage/73-minidsp-2x8-kit?sef=hcfp
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Thats good news Steve. How about usb cables into the off ramp? Is it insensitve to change on the computer side of it ? If so you could possible have the first audio streamer thats also the starting gate in an audio chain. :thumb: All you want to hear is differences in file resolution and thats it imo.
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Thats good news Steve. How about usb cables into the off ramp? Is it insensitve to change on the computer side of it ?
I have not done this test since I updated the voltage regulators. I previously had to use a Polestar with the Off-Ramp 3, but I have found that a 16-foot Belkin is fine with the Off-Ramp 4. It probably does make a small difference however. I had one report from a customer to this effect, but he did not have the latest voltage regs.
Steve N.
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I put analog distortion from compression as #2. Eliminating the preamp improves this.
Other principal digital things that affect fidelity are:
1) digital filtering - use it sparingly or not at all
2) D/A conversion technique - affects resolution and S/N ratio - use modern D/A chips, but avoid switched-capacitor techniques
3) digital cable - make sure it's 1.5m long and low-loss
Steve N.
Hi Steve, With regards to the digital cable length - Should it be less than or equal to 1.5m long or is there something special about 1.5m in length? Also, how does one determine if a cable is "low-loss"?
Thanks for your response!
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Hi Steve, With regards to the digital cable length - Should it be less than or equal to 1.5m long or is there something special about 1.5m in length? Also, how does one determine if a cable is "low-loss"?
Thanks for your response!
1.5m is the minimum length. I would try to keep it shorter than 3 meters.
Low-loss means low dielectric constant in the insulation, such as Teflon, expanded Teflon, or air. Also, to mininize skin-effect, conductors should be 26 gauge or less.
Steve N.
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Just for grins, I measured a new (no break-in) Off-Ramp 4 with Turboclock and USB Hynes reg and BNC output for P-P jitter.
It comes in around 170 psec for overall worst-case jitter on the S/PDIF output now. This is a reduction of about half due to the USB Hynes reg.
Nice. I think the Off-Ramp 5 should measure even a bit lower due to the additional Hynes regs that are designed into that one.
Steve N.
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Just for grins, I measured a new (no break-in) Off-Ramp 4 with Turboclock and USB Hynes reg and BNC output for P-P jitter.
It comes in around 170 psec for overall worst-case jitter on the S/PDIF output now. This is a reduction of about half due to the USB Hynes reg.
Nice. I think the Off-Ramp 5 should measure even a bit lower due to the additional Hynes regs that are designed into that one.
Steve N.
Steve, any idea how this compares to some of the competition? And what is meant by "worst case"? 170 psec seems kind of high, IIRC the Northstar USB DAC measured somewhere around 170ps.
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Steve, any idea how this compares to some of the competition? And what is meant by "worst case"? 170 psec seems kind of high, IIRC the Northstar USB DAC measured somewhere around 170ps.
Take a look at JAs measurements in the Nov/Dec issue of Stereophile. He reviews the Off-Ramp.
Its important to draw a distinction between RMS and P-P jitter
Steve N.
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What I'm wondering is how Audiophilleo is managing to get 15ps p-p jitter for their devices. Are they not measuring their S/Pdif output?
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What I'm wondering is how Audiophilleo is managing to get 15ps p-p jitter for their devices. Are they not measuring their S/Pdif output?
I dont believe it. Even on the bench, just measuring the clock alone driven from the very best power supply, you will not get 15psec.
It is best to make the decision based on sound quality anyway, not measurements. Even JA realizes this now.
Steve N.
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What do you make of this measurement, comparing the Audiophilleo1 to a specialized, ultra low jitter clock, and a Grimm Audio CC1 master clock? The AP1 is right in league with these devices, suggesting that Audiophilleo is not making up their jitter measurements. I'm not making claims about sound quality, indeed from what I've read from owners it seems like the OR4 is among the very best sounding converters out there. It's just that 170ps p-p jitter on the output (or 300+ without the USB regulator) just doesn't seem that impressive of a result.
(http://cdn.head-fi.org/3/32/32fc5b59_TrimbleGrimmAudiophilleophasenoise.gif)
Stereophile recently measured Simaudio's Moon Evo CD player for example at 69ps p-p on its output. Granted it costs $8K, but that includes dealer markup, and its also a CD player which adds more than a little to the cost of its internal digital circuitry.
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This is a pretty interesting thread about jitter.
http://www.computeraudiophile.com/content/Timing-errorjitter-reduction
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The plot looks good, however the different signal levels is concerning. Is this really apples to apples?
Are we comparing clocks to clocks or S/PDIF data to clocks?
BTW, a customer in Australia who has Audiophillio just got his Off-Ramp 4 with Turboclock, no USB Hynes reg. He says it beats the Audiophilleo. He is sending it back for the USB Hynes upgrade too.
Steve N.
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I think this test was measuring the clock of the AP1 vs. the other two, rather than the usual S/Pdif output. AP's specification of 15ps p-p using their WaveCrest I think was done with S/Pdif. I've heard from a few people that using bus power seems to reduce the performance of the AP quite a bit, despite the "regenerative" internal power supply. I'm amazed that the $2900(!) Sonicweld Diverter HR continues to use bus power. They obviously go to herculean lengths to try to clean it up but, why bother with all that when you can just use either batteries or a nice linear supply? I don't get it.
Do you know of any comparisons of the OR vs. the Berkeley Alpha USB? These are the two I'm most interested in. Even if the Diverter solves all of the USB power issues, the price is so high that it's silly. If you're going to spend nearly $3,000 you might as well just skip the converter altogether and buy a USB DAC.
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I think this test was measuring the clock of the AP1 vs. the other two, rather than the usual S/Pdif output.
That's what I suspected. My clocks are just as good if not better.
I also have a NEL clock that I can put on my Turboclock which measures phase noise at -128dB at 10Hz. When comparing this to my current clock from Crystek, the audible difference is small. The Crystek is -155dB at 10kHz.
AP's specification of 15ps p-p using their WaveCrest I think was done with S/Pdif.
This may be at 10kHz. At 10Hz, the plot puts the RMS jitter at about 500psec, and this is just the clock alone.
I've heard from a few people that using bus power seems to reduce the performance of the AP quite a bit, despite the "regenerative" internal power supply. I'm amazed that the $2900(!) Sonicweld Diverter HR continues to use bus power. They obviously go to herculean lengths to try to clean it up but, why bother with all that when you can just use either batteries or a nice linear supply? I don't get it.
Me either. Whats the point? Make it simpler and then charge $3K??
BTW, I discovered that my new Hynes design actually outperforms LifePO batteries. I put both in the OR4 and compared them.
Do you know of any comparisons of the OR vs. the Berkeley Alpha USB? These are the two I'm most interested in. Even if the Diverter solves all of the USB power issues, the price is so high that it's silly. If you're going to spend nearly $3,000 you might as well just skip the converter altogether and buy a USB DAC.
Agreed. I dont know anyone that has one yet, only the review in July/Aug TAS. Pflaumers background is not really digital design according to the review. Harley compares it driven by a Mac compared to a Lynx card in a PC, which is not interesting or particularly useful IMO. It's really too bad that Steven Stone did not do this review. He would have put it head-to-head with my Off-Ramp 4.
Steve N.
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Thanks Steve. A somewhat unrelated question - how important is the USB cable with the latest OR4/5, and do you have any plans to carry cables from another provider? The Acoustic Revive cables seem really impressive, and are the only ones I've seen described as comparable with Lee's cables.
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Thanks Steve. A somewhat unrelated question - how important is the USB cable with the latest OR4/5, and do you have any plans to carry cables from another provider? The Acoustic Revive cables seem really impressive, and are the only ones I've seen described as comparable with Lee's cables.
I'm convinced that any cable differences are small and due to the common-mode noise, not jitter in the signal. I have customers that swear that cables dont make any difference and others who do. It may just be the AC outlets that they are plugging into causing ground loop noise.
I made a filter for this noise and it does improve things, but that test was done when I had my Mini plugged into one AC circuit and the Off-Ramp into another. Need to try this again now that everything plugs into the same AC circuit.
Steve N.
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Just got my Stereophile, congrats Steve on a great review.
Chris H.
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Do you know of any comparisons of the OR vs. the Berkeley Alpha USB? These are the two I'm most interested in. Even if the Diverter solves all of the USB power issues, the price is so high that it's silly. If you're going to spend nearly $3,000 you might as well just skip the converter altogether and buy a USB DAC.
the only one I've seen:
http://www.stereo.net.au/forums/showthread.php/41477-Bryston-Berkeley-Alpha-And-Off-Ramp?highlight=berkeley+ramp
Ok - the Alpha. Tried it with my Metrum. I think it is above the Audiophilleo but maybe with a slight milkiness. Hooked up the Off-Ramp - entirely different class - afraid it blows the Berkeley away. More analogue like, richer, greater detail, total lack of any milkiness. Everything I have tried against it is the same - the Wavelength and now the Berkeley come the closest - I rate the Berkeley about the same as the Wavelength from memory. Considering its cost I would have expected it to be closer but there you go.
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Cool. It outclasses the Berkeley and the Audiophilleo. The only one left to beat is the new Diverter at $2800.00. :thumb:
The test unit did not have the USB Hynes reg in it either.
BTW, I did further testing of my USB cable filter. Makes a huge difference, even if the Mac Mini is plugged into the same AC outlet as the Off-Ramp or Overdrive. I'm sending one to JA at Stereophile to try along with his USB Hynes upgraded Off-Ramp 4.
Steve N.
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Steve,
Will the HotRod dac be based on an OR5?
If yes how come there is such a small price difference with the addition of a complete dac section.
Roger
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Steve,
Will the HotRod dac be based on an OR5?
If yes how come there is such a small price difference with the addition of a complete dac section.
Roger
It uses the USB module of the OR5, and a one of the power supplies. These typically cost $350 and $300. This leaves enough for the D/A part and output stage. It will not have Turboclock. A stock OR5 is $1299.00. This should come in about $1499.00. Just an estimate.
Steve N.
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Will turboclock be an option?
Roger
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Will turboclock be an option?
Roger
I doubt it. I dont think it will fit anyway...
Steve N.
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nevermind
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nevermind
See the new thread:
http://www.audiocircle.com/index.php?topic=103563.0 (http://www.audiocircle.com/index.php?topic=103563.0)
Steve N.
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Just got a Meridian Explorer and am wondering if Off-Ramp 4 or 5 would do anything. Any advice?
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Just got a Meridian Explorer and am wondering if Off-Ramp 4 or 5 would do anything. Any advice?
I'm afraid not. Its already got a USB interface. If it had a S/PDIF input, the OR5 would help.
Steve N.