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DAC tour

Just a note, a 5V PS (for charging) was not shipped with the ISO devices on this tour
A 5V PS of at least 1 Amp is needed (higher current output is better) - DC input on ISO devices is the same as other Ciunas devices, a 2.1mm socket.
Nor was a USB data cable provided - I'll see what I have available to send.
 
Ciunas Audio said:
Thanks Steve
Glad you liked it & told us the rest of your system - it helps with context

If anyone else is interested in the ISO-HUB I will send it to them next?
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As a point of reference my analogue section is LP12/Tranquility/Khan/Skale/Keel/nude Akiva/Ekos SE/Urika/Radikal, I've had the Plinth and lid since '84 and this has always been a reference for me. In many ways digital audio surpasses analogue now and the rejection of digital noise or whatever it is more correctly called is one of the biggest areas of improvement for me. Hi res can be great but Red Book done well is pretty wunnerful to these old ears!
I will be sorry to see the HUB return but know it will be replaced by the ISO-SPDIF very soon. Frankly, I can't wait.
 
Yes, Steve you're not the first to say this level of digital audio playback can surpass analogue
Addressing this noise & reducing/eliminating it reveals just what was always in 16/44 but was buried
To me it reveals the missing aspect that digital audio lacked when compared to analogue playback - sonic realism
I can't really explain what exact aspect is changed in the sound as it involves auditory scene analysis but I have my hunches
 
Updated Tour list:

AudioAl
Davidjt

JensenHealey
Divedeepdog?? (haven't heard from him)
busb

If no one else is interested in the ISO-HUB device I'll have Steve Taylor return it to me.
 
Ciunas Audio said:
Thanks Dave
Did you notice the difference when you used Foobar?
I hope you can write something about your impressions of the ISO-DAC?
Click to expand...

System:
Pi2 + IQAudio DAC+ with carefully optimised LPS
DIY Preamp/active analogue crossover
Leach LowTIM power amp (or KT88 PP amp)
Murphy CAOW1 speakers (with port blocked) for >100Hz
ZRB bass extenders with custom amplifier/correction unit for 10Hz to 100Hz

My first impressions on trying the ISO-DAC with USB from my Levono Windows 10 laptop running Groove music was of a pretty good sound with a clean, clear and slightly distant sound compared to the same FLAC file played through my Pi2/IQAudio DAC+.
John suggested that I try Foobar instead of Groove music and it did cure the occasional click sound which happened with GM. I can't say I noticed much difference to the sound quality though.
I also couldn't hear any difference if the DAC was being charged or not.

I also tried the Pi & DAC powered from the 7V "direct battery" ISO-PS, this was fed into the DC input terminals of my LDO reg (replacing the transformer/snubber/rectifer AC input). The sound was similar to that of the ISO-DAC which after further listening displayed a slight lack of grip and clarity, noticeable mostly on bass and treble but also apparent throughout the frequency range.

At this point John suggested trying the USB output of the Pi2. Result: the Pi2 is really not suitable due to the shared USB port causing occasional short bursts of white noise.
The next suggestion was to try the Amanero driver instead of the Windows 10 driver. This resulted in the music being played back too slow - which was actually very difficult to spot becuase when I compared the playback speed with the Pi/IQDAC it was exactly the same. It took me a while to fidn that the Laptop played through its own speakers at the correct speed and only when using the USB output was the mucis too slow. I still cannot fix this problem and cannot get the laptop to revert to the Windows driver :-(. Sodding computer audio!!!

So maybe I didn't get to hear the ISO units at their best and by modest un-optimisation of the LPS feeding my Pi I can certainly make it sound worse than the ISO kit. In the end though I couldn't get it to sound better than what I have and the functionality of a USB DAC is also a downgrade in my situation, so I will be sticking with what I've got.

Thank you John for the chance to try the units!! I will try to get them posted tomorrow, but certainly by Monday they will be on their to the next person the list (actually the PS is going back to John for some checks).

Cheers,
Dave
 
Thanks Dave
Dave had already told me his findings & I suggested that he post his honest opinion.

Yes, computer audio can require some work to obtain optimal results - you seem to have hit every bump & roadblock along the way :)
But I believe your issues are to do with ground noise issues arising from the replacement of your Pi/IQAudio+ DAC with the laptop/ISO-DAC/preamplifier

I suggested grounding these laptop/ISO-DAC/preamplifier to the same mains earth point as the amplifier to see if this changed matters but I don't think Dave tried this?

You are correct that the Pi connected to IQAudio DAC+ is a more direct digital communication channel than USB but it has one major weakness, AFAIK. Not saying the Pi/DAC+ doesn't sound great but I believe it could be improved.

When I looked into the Pi a long time ago, there was one weakness in this scenario which, AFAIK, still exists - the audio clocks couldn't be located at the DAC input & fed back to the Pi which is the lowest jitter configuration & makes a significant difference. Looking at the IQAudio DAC+ board I can't see any audio clocks on it so the I2S master audio clock (MCLK) is generated on the Pi (not sure how it's derived) & transmitted to the IQAudio DAC+

The ISO_DAC's Amanero USB receiver uses Asynch USB so the computer is not the clock master & the particular configuration I use locates the audio clocks right at the I2S inputs to the DAC chip, reclocking these signals synchronously & feeding these audio clock signals back to the Amanero board. I found this to be the best sounding configuration.
 
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Ciunas Audio said:
I suggested grounding these laptop/ISO-DAC/preamplifier to the same mains earth point as the amplifier to see if this changed matters but I don't think Dave tried this?
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My system is 100% DIY. I know exactly how the grounding works and how it is connected to mains earth. With the laptop and the ISO-DAC running off their batteries I struggle to see where this alleged ground noise can come from.
The waveform I sent you was taken with nothing connected to the ISO-PS except my 'scope - which is earthed. No possibility of a ground loop and I cannot see any reason why the 'scope would generate ground noise with the ISO-PS but not with anything else I have ever used it for!

Ciunas Audio said:
When I looked into the Pi a long time ago, there was one weakness in this scenario which, AFAIK, still exists - the audio clocks couldn't be located at the DAC input & fed back to the Pi which is the lowest jitter configuration & makes a significant difference. Looking at the IQAudio DAC+ board I can't see any audio clocks on it so the I2S master audio clock (MCLK) is generated on the Pi (not sure how it's derived) & transmitted to the IQAudio DAC+
Click to expand...

I have had a KALI reclocker and Piano DAC with the Pi. The IQ DAC (with no reclocking) is markedly superior IMHO. I do understand that the Pi is a supposedly high jitter source. I also understand that the Pi2 powers the IQ through a switching regulator (the PIano was separately powered via a LPS) but it sounded better, much better in fact, than an Aurender server with SPDIF via a £1000 cable to an Aurilec Vega.
 
I don't know whether my experience helps....I went from a laptop to a fanless PC and realised a significant SQ improvement. My gut feel is that laptops are so very compressed physically that they give of huge amounts of RF with all those local power supplies being in such close proximity to each other. My Pi3 with DigiOne is very good but still not up to what the fanless PC can deliver. The Pi3 / DigiOne however is probably better than my laptop with USB.
 
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S-Man said:
My system is 100% DIY. I know exactly how the grounding works and how it is connected to mains earth. With the laptop and the ISO-DAC running off their batteries I struggle to see where this alleged ground noise can come from.
The waveform I sent you was taken with nothing connected to the ISO-PS except my 'scope - which is earthed. No possibility of a ground loop and I cannot see any reason why the 'scope would generate ground noise with the ISO-PS but not with anything else I have ever used it for!
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Dave, grounding is such a complicated area & introducing a floating PS into the mix as well as laptop & preamplifier it's very possible that you have introduced ground potential differences & a possibility for ground noise contaminating the signal ground. I'm no expert in grounding but I recognise its perceptual effects when present as I know how the ISO-DAC sounds.

My suggestion to try grounding was a fairly simple task, I thought, for both your listening & your measurements.


I have had a KALI reclocker and Piano DAC with the Pi. The IQ DAC (with no reclocking) is markedly superior IMHO. I do understand that the Pi is a supposedly high jitter source. I also understand that the Pi2 powers the IQ through a switching regulator (the PIano was separately powered via a LPS) but it sounded better, much better in fact, than an Aurender server with SPDIF via a £1000 cable to an Aurilec Vega.
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Yes, from this & what you told me via PM I believe that you have some ground potential issues but I may be wrong - it wouldn't take much to try what I suggested & confirm or otherwise, for yourself?

Anyway, if you post both ISO-DAC & ISO-PS onto AudioAl, I would be grateful, thanks
 
Ciunas Audio said:
Yes, from this & what you told me via PM I believe that you have some ground potential issues but I may be wrong
Anyway, if you post it onto AudioAl, I would be grateful, thanks
Click to expand...

I didn't mention that I had any grounding issues, if I did then sorry, it was a mistake. I've spent a lot of time (sad git!) experimenting with earthing and mains connection topology, I'm confident it's good.

Anyway, no problem I will send the DAC to AudioAl.

Ciunas Audio said:
I'm no expert in grounding but I recognise its perceptual effects when present as I know how the ISO-DAC sounds.
Click to expand...
I recognise the perceptual effects of hf noise upstream of a regulator supplying audio circuits. E.g. it's not difficult to hear the benefit of using a correctly dimensioned C-RC snubber on each transformer secondary.
 
S-Man said:
I didn't mention that I had any grounding issues, if I did then sorry, it was a mistake.
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I know you didn't say you had grounding issues, I just gleaned it from the various things you told me about your past experiences with various PSes & with the ISO-DAC.

I may have said it before but when signal ground is acting as a truly stable, noise free reference, the sound takes a jump in quality which perceptually affects the whole of the soundscape, not just one aspect of it like high frequencies or bass, although some aspects may be more noticeable initially
The soundscape becomes more realistic & more interesting, as a result - dynamics, soundstage depth, air & clarity improve.
This is not something noticed as lacking or distorting on existing system - it is only revealed when the noise is removed/reduced
 
Some info that that might be of interest?
- I experienced slow playback today (& lower perceived loudness) - it happened on a WIn10 OS with DS (DirectSound) output - when I changed to ASIO Combo output, speed was fine & perceived dynamics returned!!

This hasn't happened on my previous Win OSes, AFAIR although I hardly ever use DirectSound - it goes through the OS audio stack & is never the best sounding driver

- When Sman initially reported that he had experienced clicks during playback & that the sound was distant/not as dynamic as his RPi/IQAudio DAC+ I was suspicious that it was a grounding issue. I was reminded of similar experiences reported by users of the ISO Regen isolated USB device & posts on ComputerAudiophile reporting pops & clicks in some rare instances & degraded sound. The ISO Regen has an isolation defeat switch to address this - I have a grounding tab on my devices which deals with this but also deals with other ground issues.

Uptone (the ISO Regen guys) directed people to this post/explanation

As I said system grounding, with floating supplies in the setup can be pretty complicated & one eeds to be willing to try some grounding suggestions if clicks/pops or a sound that is lacking in dynamics.

It's worth extracting some parts of that post:
-
c) We believe the issue occurs because, with full isolation, EMI--in the air and from charges built up on the cables and around the casework--have no easy path to "drain" to. The charges build up (I think on the upstream side of the Silanna chip), and then discharge--right into the data stream coming out of the isolator chip. Those are passed along to the hub chip and to the DAC so you hear them.
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I believe this is only half the story but it's s good start. Currents will choose the lowest impedance route to ground & If this "drain" is the RCA shield from the ISO-DAC into the preamp's signal input & from there to ground, then you could well have the signal ground being disturbed, depending on the preamp design.

By providing a lower impedance path to ground from the ISO-DAC, this is the route that the current noise will take
 
As promised - second Press review is online & titled "Digital done Right"

Excerpt from the conclusions
I believe the isolation and reclocking/regeneration techniques used with the ISO products are a real step forward for digital replay at a relatively affordable price. The signature of the ISO devices is one of precision, detail and life.

For those with an S/PDIF DAC I can heartily recommend the ISO-SPDIF for those with a PC (Windows, Apple or Linux) to connect to their DAC. For those eschewing PCs then the Raspberry Pi has fully come of age with the addition of the Allo DigiOne S/PDIF board, ideally with power supplied via the ISO-PS.

There are many options; maybe one of these options will form the basis for enhancing your digital playback.

I have to say it again – digital done right!
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Good article, I don't understand the science but I certainly appreciate the result. I hadn't planned to change from my original Ciunas but very glad you gave us fishies the chance to try and I'm loving what the ISO-SPDIF does for my music.
Best wishes
Steve
 
Thanks Steve
The technology & how it's put together is in this block diagram which might explain things?
ISO_DAC_Technology_Chart_large.gif


What you see are essentially 4 elements before the DAC or SPDIF board:
- USB isolator board
- USB reclocking/reformatting HUB with 4 output ports
- one of these isolated/reclocked USB ports is feeding USB signals into the Amanero USB receiver which outputs I2S signals
- these I2S audio signals are reclocked in the I2S reclocker

All of this is powered by internal LiFePO4 batteries.
Each of these blocks is responsible for the final sound.
 
davidjt said:
Having read 'Enjoy the music's review, I can't wait. :)
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Sorry I pushed you down the list - I thought you hadn't got suitable listening setup until back in England - you are next in the list

List is currently
JensenHealey * currently auditioning
Davidjt
Divedeepdog
busb
Christray
 
So - my impressions. I am not a audio golden ears so reviews are not something that I feel well qualified to attempt.

Here is my experience.

I have a odd system. Marantz 7007 universal DVD player. Amp is a very late models Roksan K2BT (bought just before K3 came out), driving Gale 401A speakers (fully rebuilt by expert) in a semi-dedicated basement snug cum office. Well damped with low celiing, soft sofas and thick carpet. It is a very quiet ambience down here at night. I have no known electrical noise issues - no buzzing, radio breakthrough etc.

Lately I have been ripping CDs to an older model Innuous Zen ripper/server with a 2TB drive installed. I have a Cambridge Audio DAc100 which takes signal (digital COAX) from the Marantz although that is also directly connected by Phonos to the Roksan, an Optical link from TV and the USB from the Innuos.

Sounds great to me and I am not in upgrade-itus mode.

Dropping the ISODAC in place of the Cambridge Audio I could only use USB from the Innuos. Control is Ipeng on an old Ipad2.

Tested like this the ISODAC sounded a little less cluttered on more complex passages of anything. It was a very musical presentation and most enjoyable, certainly not dry or 'digital'. The difference was not night and day to the CA unit..after a few minutes you could easily forget which DAC was in circuit.

There was one odd difference. As the Innuos changed tracks the ISODAC emitted a slight audible 'pop' - (as though a muting circuit was engaging?) The CA does not do this. Minor quibble / comment.

Most enjoyable little trial - thank you for the opportunity.

The ISODAC will be packed up and moved along to the next tester - so Davidjt - it is coming soon! (what a great address BTW - beats ol' blighty!)
 
Thank you Martin
Glad you enjoyed the experience
Don't know what that pop is - I haven't heard this or had it reported before

John
 
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