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Antelope Isochrone + ULN8/Model 4

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So received an Isochrone OCX this evening and hooked it up via an Apogee BNC wordclock cable to the Amarra Model 4. Well, let me cut to the chase.... Wow! Quite an unexpected change. I was told by sweetwater and a few others I probably wouldn't notice the difference until after listening for a while and then taking it away. Not so.... quite a big change top to bottom (I think a couple members here have commented that the Antelope DA had a great impact as a reclocker so was hoping for the same here). I've not spent a lot of time with it yet obviously, so will do so and report back. Easy to A/B as I just change the clock source from the interface software switch with the Model 4. The most obvious changes: (1) soundstage took a massive outward leap to the point of almost being disorienting at first. trying to sort out how I feel about it but there's no question its far more immersive and fun with the music I've just listened to. It's interesting, and not quite sure how to articulate this one, but I'm hearing different room reflections and response / timing (I have no idea if I'm hearing more of the room response from the original recording, or if a change in the sound is interacting in a different way to my own room's acoustics), (2) improvement in transparency. quite apparent when switching to the Isochrone, and very obvious when switching back to the ULN8's internal clock, which is veiled and flatter sounding in comparison. No increase in edginess or hash sound which I was on the lookout for (although the highs seem a little brighter on some material so far), (3) bass through midbass is more controlled and a little less emphasized, but need to listen to more appropriate listening material. The ULN8 is so well designed that I hesitate to mess with something that's so good on it's own, so will need to take some time going back and forth to see if some of the changes come at a cost of the great "natural" sound the ULN8 has on it's own (the changes noted above certainly have the potential of becoming a little fatiguing).


I will also try a couple different power cords on the Isochrone (just using the stock power cord), and will add some isolation feet as it's sitting flat without feet on the rack surface (rack mount style unit).


A practical downside of using this unit is the manual front panel switching required to change sample rates. It's not a big deal for me as the vast majority of my listening is 44.1 (haven't tried hi res yet), but I do have a bunch of hi res material but guess I'll have to contain myself to one sample rate at a time with that for now (perhaps Antelope will come out with a version with a remote control at some point). In this regard the Antelope DA is a lot more convenient when used with AES/EBU sources like the lynx card, etc.


UPDATE 2/7: well, having now spent the weekend living with it, I can say without hesitation his clock is remarkable and a wonderful pairing with the ULN8. It makes for a transformed listening experience. Will report back with the addition of the 10M add-on to see what relative impact it has.


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Silverlight I've been waiting for someone to externally clock the ULN-8 and report what they heard. This is cool to see so I have to thank you much for posting. I've read endlessly about external vs. internal clocking theory so I'm not making statements to argue or start a war about theory. I know theoretically external clocks add more jitter but from what I've researched and understand the amount of jitter clocking externally adds is so small that it's completely outweighed by the result of the sum of its parts just as we've discussed DAC design. I go with what I hear, and I'm extremely picky. My picky ears like what my master clock does very much so and from what I've seen some of the external clocks out there are simply better updated designs compared to many internal clocks being used currently. I'm a believer in external clocking via as short a BNC cable as possible (I've done comparisons with 3 meter vs. 1 meter with a noticeable change in quality for the better with 1M but I'd like to try one that's around 10" long for another comparison. Even Dan Lavry recommends the shorter the better with BNC. I use the Black Lion Microclock MKII master clock; a fantastic piece alone but a steal @ $475. It's cheap because it only has 3 outputs & a small basic stainless steel chassis vs. the 8+ outputs and fancy cases you see on most pro clocks. I'm going to order a linear supply for it in the near future. The company is small and humble focusing on quality for the audiophile and recording engineers without the expenses of a major one. They redesigned the Digidesign 192 box used for Pro Tools HD recording from the ground up and are using it at Black Bird Studios in Nashville. They compared their redesigned interface with top converters like Apogee and Lavry Gold and preferred the Black Lion redesign. Geoff I've recently changed setups (not on purpose) temporarily (couple months) so the Microclock is not in use. If you are at all willing I'll be glad to send it to you for a comparison to the Antelope. Also check this video out on youtube, a couple of different audio reviewers (one of them being Jay from 6moons) listening to the ULN-8 slaved to the Antelope Trinity + 10M combo:

So when are you going to step up to this ? ;) jokes


david is hear[br]http://www.tuniverse.tv

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Hey David - you joke, but after the improvement I've heard tonight with the OCX, it's damn tempting to add the 10M....

I just finished listening to some hi res 192 and 176 material. it's just incredible what this clock has done to transform the sound. Now that my ears are / have adjusted, its quite remarkable. It really has transformed the experience - the instruments just sound more darn real, and I'm hearing the space of the recording site/location like I never have before.

I went with a 3' BNC cable also with the idea to keep it as short as possible. Had you done some research into your BNC cable selection? I just went with the Apogee b/c that's the best one I saw at Sweetwater.

Thank you for the kind offer to test the Black Lion, I'll PM you follow up.




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It's not a pass-through of the digital audio signal like the Antelope DA (reclocker), it's just a master clock that provides a word clock source for the ULN8. Just need one wire (75 ohm BNC cable from the OCX's word clock out to the ULN8's word clock in). Then in the ULN8's software interface you tell it to switch from Internal word clock source to external word clock. As mentioned, if you're using the BADA, you'd definitely want to go the route of the Antelope DA as it will auto sample rate change I believe (and the BADA doesn't have a word clock input, a topic discussed quite a bit on this forum in a while back).


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My understanding is that the pass-thru AES interfaces on the DA don't actually de-jitter anything -- according to the Antelope guys, it's just a buffer, which I suppose could be very helpful if the source has a lot of jitter (eg, a computer). Given the rave reviews of the DA, my assumption (which received a shrug when I mentioned it in conversation with the Antelope guys, but admittedly, not with the designer whom would actually know) is that anything in the buffer then must be clocked out again, but this time, using their rather superior clock. However, it could well be a FIFO buffer, with no clocking whatever. No idea, but worth finding out.


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I would think that, via Firewire with the Metric Halo set as sync source, the MH local clock should outperform an external clock. In this configuration the MH should be an isochronous system slaving the computer data rate to the MH clock. Having the controlling clock right next to the DA converters should offer higher performance than an external clock. Can someone comment on the quality of the Metric Halo clocks?





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Alan, in my experience and many others, once you've heard a good external clock the theory just goes out the window. This became clear to me when I clocked a DAC with acclaimed great jitter performance externally and went whoa! From what I understand (Gordon or others please chime in if need be) internal clocks theoretically perform better from STRICTLY a jitter standpoint. We are talking picoseconds here. As we've discussed before with DACs the result in sound is the sum of its parts, not just one particular implementation. A.r.t says clocking via Word Clock, the majority of external clocking methods used, greatly reduces jitter in itself. From what Dan Lavry has said most manufacturers just don't spend nearly enough time if any on the implementation of the internal clock; they use something with good specs on paper, throw it in and say voila! Look at what Gordon has said very recently about the Sabre chip used at CES with many well known companies claiming they have great designs with low jitter but after speaking with them about their implementation said umm not quite. So basically why people are getting great results with external clocking is due to the fact that most internal clocking even with great converters is not up to snuff with the rest of the design. You could get a tiny amount of jitter more with the external clock compared to the exact same design of an internal one, but if superior to the internal one it renders that tiny amount of jitter obsolete when the result in sound simply speaks for itself. I know I've been guilty of it but I think we've become way too hung up on internal vs. external when in reality designers need to step it up and focus much more attention on an absolutely critical aspect of DAC architecture, the clocking.


david is hear[br]http://www.tuniverse.tv

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said that the Anetlope Isochrone clock is beating the internal clocks of every DAC he uses, including Digital Audio Denmark AX24 , etc. Big $$$ DACs. Dunno, but David's explanation (and Geoff's obvious feedback) seem to point to something magical about external clocking...even a $1k clock.


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The question becomes: are these "obvious" changes, like the soundstage taking a "massive outward leap", etc. improvements or simply changes.


Very often I find certain devices result in what might initially appear to be "added detail" but in the long run, proves to be added distortion as the "new" sonics are not contained in the source material but are generated as a result of the device.


One easy hint is when a characteristic of the sound is noticed on all recordings. In my experience, more often than not, this is a coloration as the preponderance of masters I've heard all sound very different from each other. The converse of course, is that the device that reveals the greatest differences between recordings tends to be the more neutral one.


I wonder about the switch back to the "ULN-8" (by the way, is it a ULN-8, from Metric Halo or a Model 4, from Sonic? they are the same and they are not the same, as Sonic modifies the software) sounding "veiled and flatter by comparison" and if it is a function of comparing something that is "brighter, etc." by comparison. I'm not saying this is the case as I have not heard the comparison myself. But there is a phenomenon, well known to mastering engineers, that I call "getting lost in A/B Land", where comparing a bright source with a neutral one makes the neutral one sound "dull" by comparison.


Further the comment that "the changes noted above certainly have the potential of becoming a little fatiguing" is something I'd be curious to hear a follow-up on in time. Personally, I've never heard a true increase in neutrality to suggest, much less become, fatiguing.


My experience so far with external clocks has been that they help when the internal clock is bad. With a good internal clock, the best they can do is equal the sound and more often than not, they don't.


But... personal preference and sensibilities may also come into play.

I know some folks have talked about third-party power supplies for the '8 too and what I've heard so far has either been a degradation of the stock supply or at the very best, to my ears, the equal (i.e. not detectable difference - other than an extra, large box at extra expense).


I'd be very curious to hear a device that improves what I see as the already quite impeccable clock in B.J.'s design.


Looking forward to hearing more comments as the hours spent with the device increase.


Best regards,






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Couple of thoughts Barry. Now having spent some time with the Antelope in use, is that it's definitely not fatiguing in any way. It was just such a meaningful change that I needed to acclimate. My first post was deliberately overly-balanced, which is my general approach to things. I don't make strong statements unless I really mean it :) What I'd say about soundstage now is that the music is far more immersive and live ("you're there" sound), but that gets me to the second point, and you touch on it. The degree of change in the sound has varied widely with the music source (this is very different than my experience with another popular leading DAC I had where I noticed a HF characteristic and sounstage expansion that was consistent and always there and less natural in comparison to the ULN8 but a sound signature that many people like). A few albums had very little difference while others were enormous. I have 100% conviction that adding the clock has dramatically improved my personal listening experience, and when I switch back (either A/B, or after an hour and go over the same songs), I'm really missing something. So can report it's no longer a first impression for me. I'm giddy-excited to get the 10M atomic clock hooked up tonight to see if it has further impact, and will post feedback.


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Hi Geoff,


So is the 10M a replacement for the Antelope OCX or does it work in conjunction with the OCX? Thanks for sharing your experience with the OCX. Might be my next upgrade. Seeing that we have the same speakers, it's fun to see your experiences with the various upgrades you are trying out.


So no Cary preamp in the chain anymore?




Sonore Music Server>MSB Platinum Signature DAC IV>MSB M202>Eficion F300 Speakers

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Barry - wanted to also say that you know how much I love the ULN8/Model4 and BJ is definitely in the genius category for this. The comments I've made about the impact on the clock are in no way meant as constructive. They're purely there to share the exciting possibilities of a high quality external clock with this or any other DAC with a word clock input. Between these two clock devices, I think I've invested over $7k, which exceeds the cost of the DAC itself (which by itself shouldn't be taken as an indicator, but perhaps that suggests the possibility of better clocks being available than what's built into the DAC's we all use, implementation aside and another matter entirely as discussed above).


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@Barry - thanks, will do!


@ Chris - good to hear from you, and hope you're enjoying the F300's! The OCX works in conjunction with the 10M. The OCX has an atomic clock input on the back. In it's presence, it will then switch to or slave to the Rubidium clock instead of using it's internal crystal clock (pls don't ask me the physics behind it...).




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" the Anetlope Isochrone clock is beating the internal clocks of every DAC he uses, including Digital Audio Denmark AX24 , etc. Big $$$ DACs. Dunno, but David's explanation (and Geoff's obvious feedback) seem to point to something magical about external clocking...even a $1k clock."


damn, just when I thought the budget was about to recover. :)


And if I understand the setup configuration, this device has no chance of making it's improvements by reducing AC or other types of noise (as with the Antelope DA).





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Well, have spent an hour listening to the Isochrone OCX with the 10M added to the mix. I don't even know where to start. I had to leave the room just to write this and walk off my reaction (I'm even loving the heck out of recordings I'd put in the bucket of lower quality, where I'm actually able to hear the artist or instrument emerge realistically from the compressed bits and bytes). The change is immediate, and it's big. No need to keep describing. I LOVE this hobby....


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Geoff, I know that John Hughes from VRS uses the OCX and 10M with his ULN-8/Model 4 and I recall him telling me they made a nice improvement. Would be cool if Barry could try the combo so he could weigh in with his impressions...any chance of you two reuniting for a demo? This also heightens my interest in the soon to be released Antelope Zodiak DAC line, especially the top of the line which will sport a very well designed analog output stage with volume control.


Mac Mini / Pure Music > Firewire & USB > Metric Halo LIO-8 > Hypex NCORE 400 > Geddes Abbey Speakers > Rythmik Servo & Geddes Band Pass Subs // DH Labs Cables, HRS MXR Isolation Rack, PurePower 2000, Elgar 6006B

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No surprise at all that you were overwhelmed by the OCX+10M combo because I had that same experience when I came over to my friend's place about 2 months ago. He had an OCX+10M feeding his RME ADI-8 QS and RME souncards. The soundstage was at least doubled in depth with the addition of the OCX and further doubled with the addition of the 10M. More significant was that the improvement of the 10M is not only a matter of quatity but actual improvement of quality in terms of details, tone colour, timbre of instruments, image everything. Everything was so right that we thought it couldn't be better. And we tried the combo on my Prismsound Orpheus and we get a similar result. So I have to surrender and buy the Antelope clock but instead of buying the OCX+10M I decided to buy the Trinity+10M because it is said to be the fourth generation running on 64bits and can go up to 384. When my clocks arrive a month later I took the Trinity to my friend's place and did an AB of the Trinity+10M to OCX+10M. To all our surprise the Trinity+10M brought us to an even higher level that is as significant as what we initially experience by adding a 10M to the OCX. As a result my friend has to upgrade his OCX to a Trinity. That was only last month when all these happen to us here in Hong Kong. Although we are not using Metri Halo or Amarra I believe the RME and the Prismsound are of comparable quality so I just share our experience here on this thread.


One more experience to share is the BNC clock cable. This is very important. We have tested Apogee, Cordial, Acoustic Zen and Oyaide and also the ordinary cheap stuffs. Our conclusion is that one cannot save here and we strongly advise using pure silver BNC cables. The Oyaide silver coaxial cable together with the pure silver BNC plugs also from Oyaide is excellent and also has good cost performance ratio(about US$120 for a 1 metre). I only use 1m and 1.5m. The Acoustic Zen BNC cable is also good but more expensive and has a character of its own and should not use too many in the setup. Tha Apogee is only fair in comparison to these silver cables because it can only achieve a result of only abouy half of what one can get from these silver cables. You've got to try it out !! Cheers!!


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That's great additional feedback. I was wondering about the Trinity vs OCX sound quality and was being told by a couple folks no difference but this probably just reflects their assessment of the comparative spec sheets in the context of 2 ch audio playback.


You described the sonic improvement of both units very well. Its a massive improvement in soundstage, but the shear realism and accuracy / improvement in tonal quality of instruments, voice is really remarkable and quite surprising. It really blows me away what redbook CD is capable of now!


I will track down some silver BNC cables as I figured this would probably be a weak link in the current setup.


Appreciate the suggestions!


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