[ctviggen]

I use Ver. 1.x of the Ack Dack with my Pioneer Elite DVD player as transport.  I've not tried another transport (hmmm...Maybe I should hook up my ShengYa to see what happens).  I'm very happy with the original version, and getting room treatments has allowed me to more easily discern differences between the Ack as D/A and my Proceed AVP as D/A.  I may also do another test comparing the ShengYa with the Ack Dack, although I like the Ack Dack better last time.  

Anyway, I think you can get good results with some CD/DVD players as transports.  I wish I had a oscilloscope so that I could hook it up to my Pioneer Elite DVD player to see what the digital output looks like.

My only complaint about the Ack Dack is that you have to remember to turn it off.  I've left it one several times.  I'm going to program my Pronto Remote to warn me to turn off the Ack Dack.

[csown]

Anyway, I think you can get good results with some CD/DVD players as transports. I wish I had a oscilloscope so that I could hook it up to my Pioneer Elite DVD player to see what the digital output looks like.

Bob, I totally agree.  The problem is that they're so hit or miss and they get obsoleted so fast that I can't recommend them reliably.  I can't think of a player in recent times that's been active on the market for more than a year.  The higher end stuff tends to do better... Some members of the Elite line are quite satisfactory, as are some of Sony's ES line.

It's moderately easy to measure RMS jitter with a scope but you should have something that does at least 250 MHz to see anything useful on good transports.  Analog scopes tend to be more utilitarian here, which is good because they're cheaper.  When you're measuring, be sure to stick a 75ohm load on it or else it will look really odd.

My only complaint about the Ack Dack is that you have to remember to turn it off. I've left it one several times. I'm going to program my Pronto Remote to warn me to turn off the Ack Dack.

I thought about this - say sticking a little buzzer in the dAck! and having it count the hours for you before ringing.  I finally decided against it because the total play time is flexible, plus people don't want to hear a buzzer go off while they're listening to music and an unobtrusive beep or flashing lights would probably be non-effective.  It would be even worse to have auto-shutoff.  I suppose we could have a "midly obtrusive" buzzer go off after 10 hours or something...  what do people think of that?  (it would be pretty useless when your batteries start getting old and don't last that long anymore).

-Chris

[csown]

Oh, BTW I took a look at the data on the FP-SPR1 S/PDIF repeater/amp.  It only gives you 200ps for 200mV peak-to-peak signals.  The S/PDIF spec calls for 100mV so you're only going to get the 1ns RMS spectrum in 90% of cases except for some odd out-of-spec equipment.  Looks like the buffers need a really high slew rate input to catch that transition and buffer it out so the performance isn't as good as I'd have thought.  Well, it's probably still pretty good compared to a lot of toslink-coax converters out there and more versatile to boot.

-Chris

[doug s.]

Oh, BTW I took a look at the data on the FP-SPR1 S/PDIF repeater/amp.  It only gives you 200ps for 200mV peak-to-peak signals.  The S/PDIF spec calls for 100mV so you're only going to get the 1ns RMS spectrum in 90% of cases except for some odd out-of-spec equipment.  Looks like the buffers need a really high slew rate input to catch that transition and buffer it out so the performance isn't as good as I'd have thought.  Well, it's probably still pretty good compared to a lot of toslink-coax converters out there and more versatile to boot.

-Chris

doesn't most actual signal when music is playing exceed 200mv?  i thought that's what's important - the music signal.  this is what i observed, when hooking up a multimeter...

doug s.

[BeeBop]

I thought about this... or flashing lights ...  what do people think of that? ...

I have aversion 1 dAck!. I say go for the flashing light Christopher. It is unobtrusive, but people will be watching for it if they are concerned about this issue.

[bubba966]

Can a 12v trigger be added to the dAck! so that when your pre/cdp/whatever is turned off it turns the dAck! off as well?

[audioengr]

Chris - Why dont you do a version where it runs off the battery until it gets to a low voltage and then the charger charges it while an AC supply takes over for the battery.  Then when the battery is fully charged, the battery takes over again...a hysteresis loop.

This type of conveniece is worth money to people.  I believe that TI or Maxim makes controllers that will do this.

[Daniel]

I like Steve's idea.  I'd pay extra for that, though you'd have to be clever to find a way to prevent endless charge discharge cycling of the battery if it were left on for days....

I have a bass unfriendly pre-amp with only 10K ohm input impedance.  I plugged a dAck! version 1 into it and there was just no bass at all.  Any chance for me with version 2?

[JohnnyLightOn]

Worrying about forgetting to shut off the unit is something that would be nice not to have to do.  I would pay a bit more for an automatic solution if one could be implemented.  A reminder light or buzzer would be a decent alternative as well.

[BeeBop]

I like Steve's idea.

Me too!

[csown]

Hi Guys,

Have a few minutes of fresh air out from the manufacturing cave.  Thought I'd catch up on forum posts.  

Doug:

doesn't most actual signal when music is playing exceed 200mv? i thought that's what's important - the music signal. this is what i observed, when hooking up a multimeter...

The datastream is spec'ed at 100mV peak-to-peak.  That is the S/PDIF standard, and it does become attenuated some by the time it reaches the receiver.  Some pro and esoteric equipment uses higher amplitude signals and the dAck! can take up to about 12V peak-to-peak.  That is monstrous and I don't think there is any equipment out there that does that.

Daniel:

have a bass unfriendly pre-amp with only 10K ohm input impedance. I plugged a dAck! version 1 into it and there was just no bass at all. Any chance for me with version 2?

It sounds like your preamp is not really 10K, or you were using a really old version of the dAck! (with the smaller output caps).  Perhaps your pre is nominally 10K at 1KHz and has some very strange impedance issues in the bass.  The dAck! should easily drive a 10K load, and in fact there is a tiny low bass hump in the 2.0 when unloaded.  The 2.0 has much faster quicker bass so it could possibly appear even lighter in your configuration.  With a purely resistive 10K load, the 2.0 is +/-0.1dB down to 15Hz so the arrows seem to point ot the pre or cabling.


Anyway, about the auto-off with optional AC-powered mode...  Back when I first designed the dAck! I had vinyl lovers in mind - they are used to intimate interaction with their gear.  I think this is a great thing... you have a vested interest in the health of the piece and it becomes a somewhat symbiotic relationship.  But I do recognize that a lot of CD-only listeners are not used to this.

Can a 12v trigger be added to the dAck! so that when your pre/cdp/whatever is turned off it turns the dAck! off as well?

And why would I ever want to turn off my transport?  .  Seriously, though, if somebody has trouble remembering to turn off the dAck!, he/she would probably forget about the transport too.  LOL

I always thought the best way of remembering to turn off the unit is to simply count the number of discs you've played.  But there definitely is something to be said about a reminder system; a small percentage of people will just need it... I'll take this feedback to heart.

About the switching to AC power source, I recognize its utility but power delivery has a heck of a lot to do with the sound. I voiced the piece to be used with batteries and most certainly did not voice it to be used with a cheap standby PSU.  I cannot offer the piece at this price (and size) if I needed to include a decent power supply.  If I were to do it, it would be done properly or not at all so that's really the bottom line.  Of course that doesn't mean it wouldn't ever be done in the future but it definitely cannot exist in this product at this price point.  I want to make this level of sound available to people who don't necessarily have the big bucks, so one has to compromise somewhere (and not in sonics!)...

Back into the cave...
-Chris

[doug s.]

...About the switching to AC power source, I recognize its utility but power delivery has a heck of a lot to do with the sound. I voiced the piece to be used with batteries and most certainly did not voice it to be used with a cheap standby PSU. I cannot offer the piece at this price (and size) if I needed to include a decent power supply. If I were to do it, it would be done properly or not at all so that's really the bottom line. Of course that doesn't mean it wouldn't ever be done in the future but it definitely cannot exist in this product at this price point. I want to make this level of sound available to people who don't necessarily have the big bucks, so one has to compromise somewhere (and not in sonics!)...

perhaps you could rig it up cheaply so someone could, at their option, insert the ac p/s of their choice.  that way, it could be the end-user who decides the quality of the p/s he's gonna use as a back-up, if he even decides that he wants to go that route...

regards,

doug s.

[viggen]

Why not make an external ac psu as an option?  The average person can afford the dac first then splurge on the psu later.  

I just sold my tt set up because I don't like the fuss of changing lps every 20 minutes.  Needless to say, I wouldn't want to have to pamper my dac.

[rmihai0]

Hi,

I am just wondering why your are keep insisting with a 16-bit only version Chris. I already have half of my CD collection recorded in 20-bit and 24-bit 192khz. From what I understood from you, your DAC won't be able to decode that signal. So, I am not talking here about upsampling. I am talking only about decoding. PLese let me know, and let us know if you plan to launch a new version, 3.0, that will be able to decode 24-bit 192khz signal.

Thank you

[csown]

Viggen and Doug - good suggestions, thanks.  I will think about a solution carefully.


rmihai0:

I am just wondering why your are keep insisting with a 16-bit only version Chris. I already have half of my CD collection recorded in 20-bit and 24-bit 192khz.

There is no advantage to storing your CD collection at 24-bit/192KHz unless you are sampling from media recorded at that rate.  There is no improvement in resolution in resampling redbook to a high rate and you are likely throwing away a very large amount of disk space.  The fact of the matter is that the vast majority of music is stored in redbook format and, given some apparent flaws, there is still quite substantial life left in the format.  Until there is a considerable body of music that is only available in the high data rate formats, we will simply not pursue it.  At this time high data rate converters for PC are for the most part a marketing gimmick with very little practical utility ("value-added feature", per se).  There is very little media recorded at that rate and due to poor SNR, consumer grade computer equipment is utterly unequipped to yield any tangible improvement from higher bit depth.

The dAck! will decode 20 or 24 bits but will truncate to 16 of those bits.  Depending on the algorithm that converted the data to 24, one may get some loss of very low level information, so it is not recommended to pass this type of data to the dAck!.  It will convert data at up to 96KHz which will cover the vast majority of PC-synthesized sound effects and music.

Best,

-Chris

[peakrchau]

perhaps you could rig it up cheaply so someone could, at their option, insert the ac p/s of their choice.  that way, it could be the end-user who decides the quality of the p/s he's gonna use as a back-up, if he even decides that he wants to go that route...

regards,

doug s.

Doug,
I've been experimenting with a adding a minimal circuit so that I can generate crappy DC for the purposes of just burning-in the unit only. I think it has gotten me to a point whereby I can appreciate the voicing of a fully burned in unit (Rev 1). It is not bullet proof and you can cause damage    if not careful with its usage.

As Chris points outs...there is a camp that will want to put in a proper external supply and ...it costs $$$ to do it right. This is similar to what Monolithic Sound offered as an upgrade supply for MSB DACs. Minimim requirement is a 3 wire connector to some internal points in the dAck. Simultaneous usage with the battery charger needs to be sorted out and will probably void   your warranty.

There is a middle ground   in an alternative "bullet proof" design in which you can use a transformer with two secondary windings to provision crappy DC.  These are going to be more expensive than a cheap AC Walwart unit but not much more. . With this design there is no chance of damaging the unit providing you can source and correctly hook up a spare battery connector. I'm sure Chris can get a part number on it if enough interest is shown. I probably like to order a few myself as an accessory.

P.S. Curious...How much would you pay up to for such a "crappy" supply? How much for a good one worthy of standing side to side with your battery pack  ?

regards,
PeAK





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[doug s.]

Doug,
I've been experimenting with a adding a minimal circuit so that I can generate crappy DC for the purposes of just burning-in the unit only. I think it has gotten me to a point whereby I can appreciate the voicing of a fully burned in unit (Rev 1). It is not bullet proof and you can cause damage icon_sad.gif if not careful with its usage.

As Chris points outs...there is a camp that will want to put in a proper external supply and ...it costs $$$ to do it right. This is similar to what Monolithic Sound offered as an upgrade supply for MSB DACs. Minimim requirement is a 3 wire connector to some internal points in the dAck. Simultaneous usage with the battery charger needs to be sorted out and will probably void icon_redface.gif your warranty.

There is a middle ground icon_idea.gif in an alternative "bullet proof" design in which you can use a transformer with two secondary windings to provision crappy DC. These are going to be more expensive than a cheap AC Walwart unit but not much more. . With this design there is no chance of damaging the unit providing you can source and correctly hook up a spare battery connector. I'm sure Chris can get a part number on it if enough interest is shown. I probably like to order a few myself as an accessory.

P.S. Curious...How much would you pay up to for such a "crappy" supply? How much for a good one worthy of standing side to side with your battery pack ? icon_rolleyes.gif

regards,
PeAK

hi peak,

i personally, would want a set-up with only external connectors for the dc power supply of my choice.  i'd like it so that, when the batteries went below a certain output, the ack! would automatically switch to my outboard p/s, whilst the batteries would start recharging.  then, the batteries wouldn't kick back in until they reached a certain level.  (or perhaps not until they were fully recharged?  i'd leave this up to chris.)  

i personally wouldn't pay more than $100 for a dc power supply.  this is because these are readily awailable on ebay - you can get an instrument grade hewlett-packard, lambda, etc., power supply far better than the $350 monolithic sounds p/s you mentioned, for $100 or less.

regards,

doug s.

[JoshK]

Doug, such a setup would be very easy to tailor oneself in the aftermarket.   Chris really needs to focus on what the majority of the audiophiles want, not really esoteric requests, and you have to admit most of Chris's market is not going to go buy industrial grade DC PSUs off of ebay.  

If Chris made his battery supply DAC with a trickle charge, charge on off or whatever, it would be very simple to put a switch after the battery that switched to DC PSU and a connector in the back for this.  One doesn't even have to know anything about electronics really to get it done.

[ctviggen]

What kind of power supply do you recommend?  Personally, I've left my Ack Dack on multiple times because I forgot to turn it off.  I also listen longer than 4 hours and have to switch to using my Proceed AVP as a DAC.  I'd love to be able to throw in a power supply and turn on/off the DAC (or just leave it on 24/7).

[doug s.]

Doug, such a setup would be very easy to tailor oneself in the aftermarket.   Chris really needs to focus on what the majority of the audiophiles want, not really esoteric requests, and you have to admit most of Chris's market is not going to go buy industrial grade DC PSUs off of ebay.  

If Chris made his battery supply DAC with a trickle charge, charge on off or whatever, it would be very simple to put a switch after the battery that switched to DC PSU and a connector in the back for this.  One doesn't even have to know anything about electronics really to get it done.

hi josh,

well, i am not so sure about "what the majority of audiophiles want..."     any audiophile wanting a battery-powered dac, that *also* wants the ability to switch to a wall-powered dc supply, may well consider an industrial-grade p/s - as well as any more conventional *upgrade* p/s, such as that offered by msb, etc...

i agree that if chris made his dac w/a built-in trickle-charger, 95% of the work is done.  all i was suggesting is an outboard tap for the p/s of your choice.  it could be a wall-wart, a lab-grade p/s, a typical audiophile-mfr-approved p/s, etc.  

the only reason i brought up the lab-grade p/s was in direct response to peak, re: his question about how much *i'd* be willing to pay for a quality outboard p/s.  i bought a hp p/s for my origin-live dc motor kit on my oracle turntable (for ~$100) that was a substantial upgrade over the stock p/s that came with it, & i am sure it is also a lot better than o-l's upgrade, which they charge something like $400 for...

regards,

doug s.