[Danny Richie]

Both units have stepped it up a notch or two now.

The DI/O up a couple of notches now using Wayne's power supply (Bolder Cable Co.). Wayne sent one of his digital cables (data link) and an in-line Bybee filter to use with the data link too. So several of his products were used this week.

First of all Wayne's DI/O mods were a huge improvement over the stock unit and his services are highly recommended. Kudo's as well for sending out his other products just for review.

With Wayne's power supply the noise floor dropped and the unit had an all round better sound over the special ordered Rat Shack unit that was also a nice step up over the stock DI/O power supply.

The power supply, cable, and Bybee filter was all plugged in together to burn in for several days of near constant play. So it was hard for me to say just which was the greater contributing factor to the greatly improved sound when occasionally dropping an ear in for a listen. It sure sounded great though.

The dAck is a simple unit that uses really good parts right from the get go and has little to mod. My only complaints about it before was the top end seamed a little soft and it lacked a little bit of detail in the highs. I also thought at times that the bottom end seamed like it lacked a little extension or tightness when compared to the bolder modded DI/O too. Not much though.

The dAck was using a pair of 2.2uF Auricaps in the output. So out they went, and in went some perfectly matched 3.0uF Sonicaps with .01uF Sonicaps as by-pass caps.

Oooooooh buddy, those highs sound good now. Detail and clarity was much improved and the highs really didn't sound soft anymore. Bottom end seamed to come around too.

I played the dAck for several days straight through too to put time on those caps.

The showdown came today (Saturday). Gary Dodd from Dodd Audio came up with Mark Nash and Roy Jackson. All audio geeks of coarse. Ex-hippy Roy Jackson is the laid back type with a full belly of Chinese food. Gary and Mark are serious listeners with good ears, also full of Chinese food. So was I.

They knew we were going to be comparing DAC's but had no idea what they would be hearing at any given time.

I placed a foam dampening panel up in front of the electronics so they had no idea what I hooked up or didn't at any time.

For the first few runs we listened to the DI/O with no Bybee and I switched back and forth between Wayne's data link and a pure Silver piece from Apature.

As they listened they barely noticed much at first. Differences were slight and were not quick to reveal themselves. In later listening between the two Gary and I both noticed Wayne's cable gave an acoustic guitar a fuller sound while the Apature cable had a little hotter top end. I give Wayne's cable the edge but longer listening sessions are needed to notice the differences in character.

I still did not identify what I was changing and for all they knew I may have been changing nothing.

Then I dropped in the Bybee filter.

Both Gary and Mark noticed a difference of some kind and they looked perplexed a little. It was a quick listen. I then quickly pulled it back out. They listened then again, then I put it back in. Then they both noticed a clear difference and felt the noise floor had dropped, imaging was better, highs were clearer, etc. All was better for sure. Gary, at that point was sure that the DAC's had been changed and that we were now hearing the battery powered dAck. Mark agreed.

I pulled the Bybee back out again. Then back again. Both agreed the dAck clearly sounded better and really liked it. They were really surprised when I told them they were listening to the DI/O the whole time.

Neither believed it claiming there was way too much difference in what they heard. They were then surprised again when I told them the difference they were hearing was the Bybee in the circuit.

The Bybee is the real deal. It didn't just sound different. It sounded notably better. As a Bybee dealer myself I knew what they could do, but this was the first time I heard one in a digital cable. The in-line Bybee design offered by Wayne is highly recommended! Big thumbs up here!

Next the Bybee came back out. We listened to the DI/O some more then I switched in the dAck.

There was no fooling them this time. Things sounded different by a lot. Gary said, that has to be the dAck it just got way quiet. He was right. The noise floor dropped big time. Highs were clearer, imaging great, vocals were more natural. Mark agreed. Norah Jones sounded so good I think Mark started to nip out. Gary was goose bumping too.

They liked the dAck to say the least.

More switching was done but there was no way to hide which was which. There was a pretty clear difference.

Then the Bybee was added in line with the digital cable using the dAck. It was not as big of an improvement as it was with the DI/O but it was clearly easy to detect. The noise floor was now non-existing. I had never heard anything so quiet. No loss any details either. Everything was crystal clear.

I remember that at one point Gary shook his head and said something is really missing. He then looked over and said there is NO noise. Mark said yea really, go turn a fan on or something.

This was the favorite setup of the bunch. Any other combo we switched back to was a let down.

Mark said, damn every time we come over here we wind up speeding more money. Mark has to have a dAck with a Bybee filter now. Funny thing is he just bought an Alpha LS kit that same day, and now he is going to spend a little more.

I guess there is something to be said for a simple design. The dAck's no over sampling, no filtering, Battery power, and low jitter design really hit a home run today. I personally couldn't fault it now.

If I would have never heard it I would have been really happy with Wayne's modded DI/O. It sounded great too and had no weakness either, but when we switched to the dAck it was like switching to a great tube amp. Vocals got lush, gooey, smooth, and really natural. It sucked you in. Vocals had no sharp edge and could be listened to for hours.

The detail level and quietness between notes with the dAck was nearly scary.

Others may get a different opinion from these two units, and system synergy could change the whole thing, but today there were no split decisions here.

More thumbs up to Chris Own and his dAck.  

http://ack.dhs.org/

Special thanks to Wayne too for all his great mods, upgrades, and cable.

http://www.boldercables.com

Hopefully Mark and Gary will chime in too to give some further insight.

[Marbles]

Danny, what are you using as a transport, and has it been modded?

[Danny Richie]

I am using a Rega planet. It uses one of the magnetic clamping, top loading configurations.

It has been modded to accept an IEC power connector and has a MPC-12 cryo treated power cable on it.

Nothing else special about it.

[BikeWNC]

Danny,

Is the mod to the dAck! difficult to do?  Can someone with very little soldering skill perform the mod?

Andy

[Marbles]

Thanks Danny and wonderful comparison!

[Danny Richie]

Yea the Mod to the dAck was pretty easy. Just de-solder a couple of caps and solder in the new ones. All was pretty easy to get to. I couldn't use my big solder gun though. I had to use my small tipped soldering station.

The Sonicaps are also slightly less expensive than the Auricaps. Even with the .01uF by-pass caps they may still be cheaper.

I am sending some to Chris for him to try. If he likes them too then they might become the new standard in the dAck.

[jackman]

The dAck was using a pair of 2.2uF Auricaps in the output. So out they went, and in went some perfectly matched 3.0uF Sonicaps with .01uF Sonicaps as by-pass caps.

Oooooooh buddy, those highs sound good now. Detail and clarity was much improved and the highs really didn't sound soft anymore. Bottom end seamed to come around too.

Danny, GREAT review!  I like the fact that you hid the DAC's from your friends and did it as blind as possible.  You mention that Auricaps sounded better than the Sonicaps that were in the dAct, why did you choose the value you used?  Also, I have a Smart Dio (not the upgraded version you tested), do you think Sonicaps would be a step up from the caps used in the stock DIO?  Also, you mention that highs sounded clear and detailed and that bass was improved.  Unless the change is major, my memory is not good enough to remember something that I listened to hours previously.  How did you handle this test?  

Again, very good review.  I've got to hear that dAck.  I listened to the Scott Nixon DAC and thought it sounded good.  However, my system was not as resolving as it is at the moment.  It looks like I'm in need of another round of tests.

Take care,

J

[Jay S]

Jack,

I think Danny mentioned that the Sonicaps sounded better than the Auricaps (though with different values).

This is very interesting.  I've got a Scott Nixon TubeDac on its way to me.  Hantra made a point in another post that the dACK uses the TubeDac circuit board and adds a battery power supply.  I've also heard from the former owner of my TubeDac that a Siemens tube (which he also sold to me) sounds better than the stock Sovtek.  Should be fun!

[Rocket]

hi danny,

thanks for the great review.  

it really helps audiophiles and can point us in the right direction, especially an inexpensive one.

i liked the way you didn't let on which components you were using as that can often influence a person's perceptions of product.

regards

rocket

[jackman]

I think Danny mentioned that the Sonicaps sounded better than the Auricaps (though with different values).

I guess a better way of asking my question is "how much of the difference would you attribute to the difference in values?".  Also, I tried a Scott Nixon DAC on my system a while back.  Although it sounded very good, I can't say it sounded better than my Smart DIO.  Perhaps my system (which has since changed) had better synergy with the DIO.  Anyway, I hope to hear the dAck one of these days.

J

[Wayne1]

Danny,

Thanks for the review and great comments about the digital cable I make and the inline Bybee purifier.

Adding a Bybee to the digital input on a DAC DOES make a difference. It is up to each listener to decide if they like the difference. In the audition in Texas, it seems that each listener does like it

For the record, the DI/O that Danny has is just slightly modded above the smART DI/O level. It is using Dale/Vishay resistors in the filter circuit, instead of the Riken-Ohms on the MENSA level. The filter circuit caps in Danny's are also stock. I did add the additional power supply caps to Danny's, but that is about the only difference between it and the smART. So the review is comparing the smART to the dACK, not the MENSA.

I offered to upgrade the ART to MENSA for Danny, but he told me he just wanted to try one upgrade at a time.

So Danny, send the smART back to me and I will complete the upgrade to MENSA and you can try it again, if you wish.

The power supply could also be upgraded with a Bybee purifier in it, which would also lower the noise floor. Danny, since you sell Bybees, why don't you put one in series with the hot (black) wire on the output of the transformer and report back.

Jackman,

First off there is no room in the DI/O for Auricaps, Sonicaps or any of the larger boutique caps. The coupling caps have been removed from the output circuit of the smART. The dACK is using a tube output stage which requires capacitors to filter out the large amounts of DC present on the output of the tube. Op-amps usually do not have large amounts of DC on the output so there is no need of coupling capacitors,
 in most cases.

There are capacitors in the filter circuits on the input and output of the DI/O's op-amps. In the MENSA and MENSA + level mods these caps are replaced with the best caps that can physically fit in the very limited space that is left in the case. For the input filter, this means using WIMA polypropylene film and foil. For the output filter caps I use Rel-cap or Multicap Polystyrene film and foil.

As others have said, at this level of components, your preferences are a matter of personal taste and system synergy. I have compared the SN TubeDac to the MENSA in my system and I prefered the MENSA. Other folk like the dACK and SN better. Each and every system and listening room IS DIFFERENT. The only way to know for sure what will work in YOUR system is to compare them to each other, just like Danny.

[jackman]

Thanks Wayne.  I hope to get on the list of auditioners (is that a word?) for the Mensa/Bybee pack.  Hopefully, we can also check out the dAck and do a side by side comparison.  I totally agree with you about personal preference.  These designs are very different and seem to offer (according to Danny's description) very different presentations.  It usually boils down to personal preference.  

Thanks,
Jack

[markn]

You know how you read about people hearing things in their CD's that they never heard before?  Well, that had not happened to me much until yesterday at Danny's house!

The DIO sounded good, but when Danny added the Bybee filter, I thought he had changed to the Dack!  Big difference, not subtle!  Well worth the price, I will have to have one!

The overall winner for me though, was the Dack! !  I heard details that I had never heard before, and there just plain wasn't ANY NOISE!  I had not heard anything like that before.

Match Danny's speakers with Gary Dodd's amps, and the new Dack!  and you have magic in my book.

Mark

[Hantra]

I tried a Scott Nixon DAC on my system a while back. Although it sounded very good, I can't say it sounded better than my Smart DIO

Jack:

What was your system at the time, and what is it now?

Did you happen to have any Bybees in your system at the time?

B

[Danny Richie]

Also, you mention that highs sounded clear and detailed and that bass was improved. Unless the change is major, my memory is not good enough to remember something that I listened to hours previously. How did you handle this test?

I listened to it for a while, then switched the caps out and listened some more. Even before the caps were burned in the tighter bottom end was apparent.

I was also told by Chris Own and Gary Dodd that a larger cap value there would pick up the bottom end. So it was expected.

Hantra made a point in another post that the dACK uses the TubeDac circuit board and adds a battery power supply.

I am pretty sure Chris spent a chunk and had his own circuit boards made.

The dAck is not or does not use a tube output. That would probably run down a battery supply like nobodies business.

I guess a better way of asking my question is "how much of the difference would you attribute to the difference in values?".

The difference in the bottom end is directly related to the large cap value.

The added clarity and detail in the highs is due to the Sonicaps. I have and have used the Auricaps. They are good caps, but not quite to the level of the Sonicaps. The Sonicaps are more neutral, less colored, cleaner all around. So what happened in the highs was no surprise either. By-passing it with a .01uF Sonicap value didn't hurt either.

Also, I tried a Scott Nixon DAC on my system a while back. Although it sounded very good, I can't say it sounded better than my Smart DIO.

Even though there are obvious similarities between Scott Nixon's DAC and Chris Own's dAck, I don't believe there are as alike as you think.

Chris says his is different and sounds better too. You'll have to get the specifics from him and decide for yourself.

Adding a Bybee to the digital input on a DAC DOES make a difference. It is up to each listener to decide if they like the difference. In the audition in Texas, it seems that each listener does like it .

No doubt about it, the Bybee defiantly worked well in this application. It wasn't hard to decide if we liked the quiet noise floor or more noise, or if the improved imaging was desirable or not.

I decided this morning though that I would not be using a Bybee in-line with my digital input though, at least not this way. As cool as the little unit looks and as great as the Bullet plug is on it and whatever high quality input it had, for the dAck there was a better way.

There is plenty of room in the chassis to mount the Bybee in-line on the inside of the unit. I dropped one in right in between the inside of the input and the circuit board. It fit cleanly and nicely in there and soldered it right to the back of the input.

Sounds GREAT too.

This is one bad to the bone mod!

The power supply could also be upgraded with a Bybee purifier in it, which would also lower the noise floor. Danny, since you sell Bybees, why don't you put one in series with the hot (black) wire on the output of the transformer and report back.

As soon as I get a chance I will try that.

My guess is that used in power supplies might be "thee" best application for the Bybee's.

I must admit though that the cost of Chris's whole battery pack, charger and all is about the same as the retail price of one Bybee filter, and it sure is clean. No high quality cables needed either.

I especially like that the charger can be left on or plugged in all the time, and when you turn the dAck on it disconnects the charger from the circuit and when you turn the dAck off it automatically starts charging again. That is really cleaver and trouble free.

I wonder if the DI/O can be powered from one of these battery supplies and what the benefit might be if any?

The dACK is using a tube output stage which requires capacitors to filter out the large amounts of DC present on the output of the tube.

No tubes in the dAck.

Op-amps usually do not have large amounts of DC on the output so there is no need of coupling capacitors, in most cases.

That is true and Chris mentioned that if my pre-amp could handle it I could direct couple the outputs on the dAck.

Gary said, No!, that my tube pre-amp did not use any eternally and that I needed to leave some type of coupling in the dAck.

The dAck also uses some .22uF bypass caps for the power supply caps. I may change those out to Sonicaps or by-pass them with .01uF Sonicaps too.

More fun ahead maybe and can it get any better? I can't wait to find out.

Either of these two DAC's we compared can easily stomp a new one in a lot of high dollar DAC's out there I guarantee it.

One might be a favorite but both units get a high recommendation from me.

[Hantra]

Even though there are obvious similarities between Scott Nixon's DAC and Chris Own's dAck, I don't believe there are as alike as you think.

All I'm saying is the DAC was first built with Nixon's DACKit boards.  If he now has his own boards, that's great, but the similarities have to be startling if they are based on the DACKit. .

B

[byteme]

If I would have never heard it I would have been really happy with Wayne's modded DI/O. It sounded great too and had no weakness either, but when we switched to the dAck it was like switching to a great tube amp. Vocals got lush, gooey, smooth, and really natural. It sucked you in. Vocals had no sharp edge and could be listened to for hours.

The detail level and quietness between notes with the dAck was nearly scary.

Others may get a different opinion from these two units, and system synergy could change the whole thing, but today there were no split decisions here.
..

These findings echo my experience with an oversampled and a non-oversampled comparison.  As I said, the DIO would be my choice had I never heard a non-oversampled dac.  However, that combined with the quality implemenation and bare minimum of "stuff" in the circuit path just makes things SO much better and more natural sounding I can see why there was no split decisions.

Give a quality implementation of a non-oversampled dac a shot for a week or so straight and I bet you don't go back.

[nature boy]

Well it looks like Danny beat me to the punch with a review of the Bolder Cable Company modified ART DI/O and the Chris Own dAck.  For the record, my comparison consisted of the Bolder MENSA modified ART DI/O (a step up from the SMART DI/O unit Danny listened to) and stock dAck unit (Danny modified the caps).  

I used the Bolder Cable M-80 cryo digital cable, but kept my Groneberg Quattro Reference IC's in for the comparison as I preferred the sound compared to the M-80 interconnects.  My system is listed in the system section.  An extensive listening comparison of ~ 30 hours total during the last week was performed, in between yard work, fall cleaning, and completing my "honey do" list during the second week of my summer vacation.

I have to say that in general, my observations are very similiar to Danny's with a couple of exceptions which I'll note below.  Suffice it to say, these two DAC's are simply put "great products which offer cheapskate audiophiles a chance to step into the big leagues of digital sound reproduction with a decent transport or dedicated CD player."

My extended listening test were also completed on Saturday, as a Sunday listening session with fellow Audio Circle members vanished with various scheduling conflicts.  

My listening was done in system using my Audible Illusions M3A preamp as well as DAC's link up directly to the DNA LA-100 (Don Nance modified ART SLA-1).  BTW, this is a very nice amplifier which I'll be posting additional comments about shortly.  I generally listened to a full CD using the MENSA then switched out for the dAck keeping sound levels as close together as possible with a RAT Shack decibel meter.  

As previously noted and oberved by Danny, the inline bybee is the real deal.  I found it performed best with the MENSA unit more so than with the dAck.  In my system, I felt the stand alone dAck w/out the bybee filter sounded a bit more realistic.

MENSA Observations

Includes MENSA unit and Waynes special power supply w/ intermittent use of an in-line Bybee filter.  

Fully agree with Danny's comments - a huge improvement over the stock unit and his services are highly recommended. The audition kit with in-line bybees, M-80 cryo and standard cables and three types of power cords provided for an almost Christmas like atmosphere in my listening room.

The in-line bybees added more smoothness and increased detail.  A four thumbs up rating        
Same for the nitro power cord.  I have been using the type 1 and type 2 cords in my system for over a year.  The nitros, well they are a major step up.  Hearing is believing.

With Wayne's power supply the unit has a low noise floor and much better sound than the stock power supply provided with the ART DI/O.

The end result - a very detailed and resolving sound that had me thoroughly engaged in all types of music - jazz, orchestral, pop, etc.  An extended airy treble combined with a deep, clear powerful bass response.  These are two areas where I thought the MENSA bettered the dAck, keeping in mind that my dAck unit has the stock caps.  As previously noted, the in-line bybees just made things better, a touch smoother, more refined, and quieter.          

dAck Observations

The dAck is a simple unit, just a nice stainless steel case and battery charger.  I should note that charging the battery after use was simple and did not eat into my listening time.  I had the unit on a couple times for extended listening and break in (12-14 hours straight).  During these lengthy periods it took no more than 1 hour to fully recharge.  Shorter listening sessions took 10-15 minutes.  

Out of the box the first thing one notices about this DAC is what is lacks - any noise.  This is absolutely the quietest piece of audio gear I have ever heard - or more accurately not heard.  This created an almost eerie listening experience, especially in the late evening or early morning, and imparted a very special quality to the music.  

My only complaints about it before was the top end seamed a little soft and it lacked a little bit of detail in the highs. I also thought at times that the bottom end seamed like it lacked a little extension or tightness when compared to the bolder modded DI/O too. Not much though.

The sonic signatures of the MENSA and the dAck are different.  On vocals, jazz, and pop recordings the dAck has an edge on the MENSA unit.  With vocals in particular, the dAck invokes a special quality approaching some of the very finest vinyl playback (my personal reference) that I have ever heard in the digital realm.  This is the first time I have ever heard digital playback in my system approach the quality of a top notch reference vinyl recording.  I also have to give this unit four big thumbs up        

I moved into orchestral and opera recordings, the dAck exposed its weaknesses IMHO.  The highs simply did not match the extension and clarity of MENSA.  I my deep bass torture test, in went the Gladiator sound track, a couple of organ recordings, and some classic orchestral pieces.  While the MENSA excelled with a deep, quick, and clear bass (w/good distinction between instruments) things got a little murky with the dAck.  

I think that Danny's cap modification to the dAck accounts for differences in our observations about this unit.  Any observations from Danny, Chris Own or others would be welcome.  

Round Up

That said, I am at a bit of a loss to say which DAC I liked the best.  To my ears the MENSA sounded more tonally accurate across the full frequency spectrum - maintaining a cleaner and clearer deep bass and upper treble response.   If you listen to a lot of classical music, this may be the DAC for you.

If you listen to jazz, vocals, or more intimate music the dAck may be more to your liking.  The dAck's no over sampling, no filtering, battery power, and low jitter design really imparts a special quality to the music.  If the deep bass and treble response can be improved with different caps, I would be hard pressed not to recommend this DAC to anyone - period.

I also agree with Danny's observation about the dAck.  Listening to it reminded me of when I first heard a good tube amp (Quicksilver) with Vandersteen speakers.  The glorious mid-range just "sucked you in".  As Danny mentions there is something to be said for a simple design.  Vocals got lush, gooey, smooth, and really natural. Vocals had no sharp edge and could be listened to for hours.

Others may get a different opinion from these two units, me I am hoping Chris Own will incorporate the cap changes recommended by Danny as I view his product "almost sonic nirvana but just needing a tighter, cleaner deep bass and more extended treble. "

Again my congratulations to both Wayne W. and Chris Own for not only making some great products, but also providing an opportunity through the MENSA audition kit and dAck in home trials for folks to listen to these top notch DAC's in their own systems where it really counts.

Chris Own dAck
 
http://ack.dhs.org/

Wayne W. Bolder Cable Company  

http://www.boldercables.com

FYI, your mileage and listening pleasure as always may vary.

[gld]

Well, I must say it was a very delightful Saturday at Danny's this weekend. Myself and 2 friends got to listen to the modified DIO and the new Dack Danny has. I will say that the Dio has come a long way since Danny got it over a year ago. I used it for a week when he first got it, and I thought it was just OK. As time went on the mods done to it have improved it to the point where it has become a really good piece of hgih end gear. The mods done by Wayne at Boulder have made this a killer DAC. A week or so ago Danny called and told me of this new dac called the Dack. He was very impressed with it, and so the trip to Whichita Falls had to be made.When we arrived at Danny's it was food time, so we filled up on some good chinese food. We went to Danny's house and sit down for some serious listening, Danny had told us before hand that we would not know what he was changing in the digital portion of his system. we listened first and I knew it was the dio, (i had listened to it many times before) then he made a change. It all got quieter and it had better resolution thru out the entire range. Turns out all he did was add a BYBEE inline with the cable. What a difference that made! I know now the BYBEE's do work! There was absolutely no doubt when he put in the Dack, we knew it right away, somethings wrong, there was NO NOISE it disapeared. This thing was very involving, it grabbed you and drew you in. So clean and revealing.The highs were excellent,the midrange was as good as I've ever heard, and the bass was awsome. Danny told us that he changed the caps, so we didn't hear it as it came to him.I was very impressed by the sound of the Dack. It's truly amazing how much of the microdetail that is masked by the noise. This thing didn't miss any of it, it was all there and it was very realistic and natural. Great job Chris Own!!! I would highly recomend this Dack for anyone who wants simplicity and ultra high end at an affordable price. It may not be as good in all systems, but I beleive it will make big improvements in most. The ART DIO is also a very nice addition to any system, although the Dack won my vote for sure. Thanks again Danny for giving us the chance to listen to a really nice, new product

[csown]

Hi Folks,

Thanks to all of you who have given kind words about my product.  I'm glad it has been received well.  

This'll be my first post on AudioCircle - I usually don't like to do too much talking and prefer to let the product speak for itself at in-home auditions.  However, there are a few things that I wanted to clarify or comment on, because some myths seem to have been propagating about the dAck! and this Sonicap thing has been getting a lot of attention.  This'll be my one long message.


1. Mix-up with Nixon's unit:

The Nixon unit is similar to the dAck! only in that it is a non-oversampling DAC and that both are aimed at the extreme value market.  The dAck! uses a dedicated PCB that is completely dissimilar to Nixon's unit and is engineered from the ground up.



A very early development revision of this converter used Nixon's basic board as a platform on which to perform the fundamental conversion operation.  The basic circuit of all digital filterless units is roughly identical, and Hantra may have seen a photograph of the Nixon unit being used in this capacity during the early development stages.  There's a hell of a lot more to digital design than tacking on a pair of batteries!

The Nixon DAC and dAck! follow extremely different design philosophies and, in an absolute sense, are not in the same playing field.  I do not agree with Scott's method of grounding, the way he throws Black Gates at the problem, and his method of supply decoupling.  The receiver and DAC chips are different from those in the Nixon units - the TDA1545A is a continuous calibration unit similar to the venerated TDA1541A DAC used in many of the best CDPs and DACs in the past.  The Nixon DAC and dAck! do not sound much alike, other than that they share that special non-oversampling midrange.


2. Some technicalities:

It is not surprising that the Bybee made little difference with the dAck!.  Non-oversampling units will be quite insensitive to timing errors in the signal.  Digital noise rejection with the dAck! is about the best you will find anywhere, which allows users to spend less on transports and expensive cables (and filters) while maintaining the same level of performance, and use the excess to buy more music!  Of course, it always helps to have the best datastream you can get, so a multi-$K transport is not out of the question.


3. Will it work in your system?

Feedback from customers has described a noticeably specific trend.  The dAck! loves music-making systems.  Tubes are a big plus, as is generally PRaTty gear, such as Dynaudio, Merlin, and NAIM.  Analytical systems (for example, Levinson/B&W) will restrain the dAck!'s abilities.  Danny makes speakers voiced for music, and Dodd's amplifiers are top-notch in the musicality department.  That review system is one of the best systems one could hope to put the dAck! into.  


4. About the Sonicaps:

Danny wanted more in the high frequencies so I suggested to him  that the decoupling could be changed out for Sonicaps.  During the design of the dAck! long ago, I got a pair from Danny and I had found them too hot on the top.  The circuit has matured and with all the interest in the "mod", I will definitely be re-visiting them.  I knew he liked their response and that they would tip up the HF's in an acceptable way, so this was the obvious thing for Danny to try.  

The bass performance of the dAck! is optimized for preamplifiers with input impedance in the 10's of Kohm or higher.  Danny's system plays extremely low, so he is really pushing the limits of the stock capacitor's specs.   Most people who are going to spend $400 on a source component don't have -3dB at 30Hz like those wonderful Alpha LS.  In the low bass, it is easy to detect a couple-dB shift in bass, and the listeners definitely heard this in their comparison.
 
The stock capacitor is specified with the constraint that the -3dB point must be nominally 15Hz for a 5kohm input impedance in the average production unit.  In the worst case scenario, it will not surpass 20Hz, however, the rolloff of course begins in the audible range.  If you use a high-input-impedance tube preamp, you should have little concern about the bass; if you use a poorly-designed SS unit, you *might* run into some roll-off problems, but probably not.  In general, the 3.0uF value Danny used will give a bit better bass response, especially in systems with really, really deep extended bass like Danny's.  

With D/A's that are flat to almost DC, the dAck! cannot compete.  However, it was not meant to (see topic 6).


5. dAck!s with Sonicaps?

Several of you have inquired about the issue of dAck!s "upgraded" to SoniCaps.  I value very much Danny and others' input on the matter of the capacitors, but I can't change the product if I haven't had a chance to properly investigate their effect.  The sound of the dAck! is a synergistic whole of the design process and each component was carefully voiced to give a balanced listening experience.  Adding new capacitors will require rigorous testing of both short-term and long-term effects.  I will be able to say more in a few weeks and I'll keep everybody posted both on my website and on this forum.

Review readers please keep in mind that analog cabling can easily alter what you hear through the system.  I voiced the dAck! using a silver tri-braid cable similar to the Kimber KCAG.  Quite extended highs without being forward, midrange detail without fault, and excellent bass.  It's a lively cable, and may be quite different from what Danny is using.  Some of my listeners think the dAck! is hot, some think there is not enough detail.  It's up to you to decide - but remember, you have some control with those little wires that go out from the source and into your pre.


6.  Regarding the high frequencies:

The unit is voiced for midrange performance.  Being from a musician's background, the tonal texture and harmonic structure of the sound is of utmost importance.  I was a musician before an engineer, and listening always takes precedence over measurement.  Correction of the high frequencies using an analog post-filter results in some phase distortion which completely alters the soundstaging and transient dynamics.  The dAck! is the champion in midrange detail, and I will never compromise that for enhanced high frequency response.  The latter is overrated in this field.  You can continue to push the high frequencies up, but you will continually lose magic in the midrange.  This is a compromise you have to accept with non-oversampling.  

Additionally, the dAck! was designed for vinyl lovers and was intended to be quite similar to that of the best vinyl reproduction.  In addition to the "glare" you hear in conventional digital audio, the HF of high-end digital reproduction always contains an artificial air and ambience.  This is quite well-documented and a widely-accepted digital artifact.  The fact that this is not present in the dAck!'s playback sometimes makes strict CD listeners feel like something is missing (it's true of course!).  However, vinyl listeners never complain about this; in fact they welcome that it's gone from CD playback.  The high frequencies are rolled off - that is an artifact of non-oversampling that I specifically have not compensated for (see Stereophile measurements of Shigaraki DAC) - but also some of the perceived loss of high frequency you may hear people talk about is due to this lost artificial "sparkle" in the highs.


For those intrigued, when you get the chance to listen to the dAck!, the first time go ahead and listen for those classic things such as imaging, frequency response, and detail.  But keep in mind that this is a different ball-game - this is design for long-term listening satisfaction.  If you do become an owner, I wish for you not to sit there analyzing the space around instruments and checking if you can hear those lowest organ fundamentals every listening session.  I want it to accompany your day-to-day activities.  I want it to keep you up late at night because you want to put in CD after CD.  I want it to always give you goose bumps when that soft voice begins to sing.


Best,

Chris
Ack!Industries