[BobM]

Here's my new Monica II DAC you can find out more details on the DAC kit itself here: http://www.diyparadise.com/dackit/1545dackit.html



Rather "liquid" sounding DAC, if I do say so myself.



I used commercial grade vinyl floor tiles to damp down the tin box. It's not a perfect container, but I just couldn't resist implementing it this way. That's the 12V sealed lead acid battery in the back. I can run the DAC using the battery, or by plugging in a 12V DC wall wart. I've implemented a double throw, double pole switch, with a center "off" position to switch between the battery or AC wall wart if I need to.

Rather unique, don't you think? More details to follow.

Enjoy,
Bob

[BobM]

Here's the DAC input and audio output RCA's on one side (insulated from the chassis itself):


And the DP-DT center off switch and battery charger input jack on the other side:


I've got a 12V red LED to indicate power on, and a second green/blue LED to indicate lock on the digital signal.


Bob

[BobM]

Here's more of a close-up of the insides (sorry, I thought the picture was a bit brighter when I took it, to show more details). That curled up wire in the middle is the jack for the AC wall wart, in case the battery is drained and I need to run the DAC on AC.



Enjoy,
Bob

[jermmd]

That's really cool, Bob.  I think it would go very nicely with PhilNYC's Blue circle lady.


Joe M.

[BobM]

That's really cool, Bob.  I think it would go very nicely with PhilNYC's Blue circle lady.
Joe M.

Lets see if I follow this thought ...

A lady drunk on Glenfiddich (so she's got good taste in liquor) ...

... who's also into audio (so she's got good ears, although they're not visible with that hat on her head) ...

... willing to be surrounded and put up witha bunch of geeky audiophiles in their native environment (HE 2005) ...

... but that hat and dress!!! OK, so she's got no taste in clothes.

Enjoy,
Bob

[dwk]

Okay, cool DAC, but really - can it play anything other than bagpipe music now

[mcgsxr]

Nice work, and I assume that it does a great job on rim shots...  

[Panelhead]

The unit looks great. How does it sound?

                       George

[BobM]

This is my first taste of an Non-Oversampling DAC in my system. It's a fun and inexpensive test for me to see how NOS sounds. So I'm remaining open in my opinions at this time as to how it's all gonna shake out in the end.

Overall it is very liquid sounding, which is why I thought the case was most appropriate. Smooth and enjoyable. Not as defined or punchy as my oversampling modded ART DI/O, but definitely musical. I would say, as have others, that NOS DAC's are probably most appropriate for systems that tend to brightness, are overly clinical sounding (hi-fi), or are horn based. This DAC would smooth them out nicely. I would like to try eventually it in several friends systems that sounded top end heavy to me.

Unfortunately for me, my system is slightly more on the laid back side than the bright side. That should put my comments on "Glen-Monica's" tonality into context for you'all -- YMMV.

I've got about 100 hours on "Glen-Monica" now and the top end is getting better. I was getting a wee bit worried that it would continue to sound rolled off on top, but I guess these Black Gates really do have a slow burn-in. I'll give it another week and hope it continues opening up some more.

I think the bottom end is a little soft too, but more time could help there too. It's not as punchy or as well defined as I'm used to, although a 16Hz organ pedal bass tester track that I have went all the way down. It's more the kick of the drum or the snap of the bass guitar that doesn't quite snap all the way (the leading edge transients are a bit softer). Many people believe this is actually more natural, overly defined bass being wrong - perhaps it is. Battery vs AC doesn't seem to make a difference, so it's getting all the power it needs either way.

I played with the AC vs battery powered options last night. Battery power  definitely makes a subtle but very real difference. All the remarks about the background noise dropping away now makes more sense to me. Nothing changed in the notes or tones themselves, but they just seemed to stand out more - like the background dropped away a bit (duh), making it more 3D (sort of). Hard to describe but if you hear it you'll know.

Enjoy,
Bob

[tianguis]

Bob:
       Nice work. However, I believe it would sound better in a Macallan 25-Year box.
       You mention a lack of snap. I've been messing with digital cables on my battery Nixon DacKit and find cables make a big difference in attacks (and other areas, of course). Additionally, I've found that a battery bank (Pana FC's, 25 v., 5400 uf) placed across the terminals of my SLA nicely increase snap and dynamics of both the DacKit and modded T-Amp.

Regards,
Larry Welsh

[doggie]

Bob:
       Nice work. However, I believe it would sound better in a Macallan 25-Year box.
       You mention a lack of snap. I've been messing with digital cables on my battery Nixon DacKit and find cables make a big difference in attacks (and other areas, of course). Additionally, I've found that a battery bank (Pana FC's, 25 v., 5400 uf) placed across the terminals of my SLA nicely increase snap and dynamics of both the DacKit and modded T-Amp.

Regards,
Larry Welsh

I have found the same as Larry. I just added more capacitance to both my battery run DakKit and my battery/modded SI. The extra capacitance after the battery gave the system better pace and better transient resonse. I also have been playing with digital interconnects. So far I have tried two Cardas cables, an RG59 handmade job, an RG59 Rat Shack cable, and a Redwine Audio RG59/75ohm cable. I have an RCA on the input and a 75ohm connector on the DAC side. So far the RedWine cable sounded the best, although the cheapo RS cable was not too bad.

[yeo]

hi guys!

i don't think digital cables make much of a difference. it will make hell lot of difference for those "non-asynch reclocked" dacs. as with the case of monica2, i think very subtle difference. but try it, and hear for yourself.

caps between sla or better still, just at the input power jack of your monica2 chassis, is a good idea. i wouldn't know how much to try. just try and listen to it.

however, a word of caution. the 1545 and 1541 are not known for their dynamic qualities. the 1543 is clearly more dynamic in the systems i have compared all 3 dac chips. that said, try it and let us know how it works out!

err, bobm, nice box you hv there! one of my customers has the monica2 in an altoids box! you 2 got the "wildest" chassis i hv seen so far for monica2. keep up the good work!

yeo

[tianguis]

Yeo:
       Your point about cable differences in a re-clocking DAC is valid. I guess my brain was asleep. I'd expect cables to have less of an effect on your DAC than one which doesn't re-clock (although I've been messing with some surprising, non-audiophool digital cables, and they may surprise you, also!). Of course, the difference is in the listening. I'm hoping to hear BobM's Monica soon. I may have to build a Monica, though!

Regards,
Larry Welsh

[BobM]

I found a 6800uF 25V cap lying around, bypassed it with a .01uF poly cap and soldiered it onto the board where the power supply leads connect.

The results are definitely better snap to things than before. Micro dynamics and leading edge transients. I'm also hearing better macro dynamics when called for too, although, like Yeo said, its not an overly dynamic chip compared to my DI/O (which is pretty dynamic).

The top has opened up a lot more not that I've got 100+ hours on it. It probably will open up more in the next 100 hrs, but I believe the power supply cap has already helped there too, making those tinkly things better defined than before.

My battery (5ah) finally ran out of steam after about 60+ hours of constant use, so it's recharging now. It's nice that I don't have to recharge it after every listening session like the Ack DAC owners do.

Thanks for the tips everyone,
Bob

[BRN]

I picked up the Monica 2 a couple of weeks ago and it is still breaking in. I did have a scare when I moved the LED from the board to the front of my Radio Shack box. I guess my soldering iron was to hot and I damaged the lead that goes to two of the power regulators for the CS8414 and XO chip.  I was able to jump power to the regulators and get the DAC working again. Thanks to Yeo I was able to discover the problem and fix it. I have not added the caps to the battery, but will give it a try. I did pick-up two Lundahl transformers that I'm using to inverse the phase and step-up the output to 1:2. When I first hooked-up the DAC with the transformers I noticed that there was more air and distinction to individual instruments and vocals, but the high frequencies were not that smooth, a little bright. The transformers really made a positive difference to the sound. I now have about 50 hours on the DAC and transformers and DAC are really sounding much better. The highs have smoothed out and the mids are more detailed and natural sounding. I’m very pleased with the DAC so far and can’t wait for it to be fully broken in.

BobM I like the case you used for the DAC. Looking at it makes me want to sit back in a comfortable chair with a drink and enjoy some music. I think that my next project will have to use some type of unique case. I will now think outside the box (LOL).  

Thanks,
Brad

[BobM]

Does this DAC invert polarity? What does that actually mean to me, sonically? Is this the same as "phase" (I believe that's what is being referred to - correct me if I'm wrong)?

I've heard 2 things about polarity/phase on CD's (a little conflicting in each philosophy):
 - every commercially produced CD alternates polarity, track by track, due to the burning process. So even tracks are in phase and odd tracks are out of phase.
 - most CD's are a crap shoot with regard to polarity. Some are in Phase, some are out.

So putting in transformers to reverse the phase/polarity really wouldn't be an "absolute" need, if either of the 2 statements above is correct. Although it would be nice to have a switch that allows me to flip phase when needed.

Am I off base here or mixing metaphors or something?

Thanks,
Bob

[BRN]

I had read a post about the Monica 2 that stated the DAC inverts phase. I then confirmed it with Yeo that indeed the DAC inverts phase. I do not know anything about the burn process so can not answer that question. I did not put a switch in, but it can be done, something I can do later.

Brad

[BobM]

I've got more than 150 hours on the DAC now and I have to say you all were correct about the Black Gates taking their sweet time. The top end opened up nicely. It's expanded and detailed with decent soundstaging and deep bass.

I haven't done a real head-to head yet between the Glen-Monica and my modded DI/O to really nail down the praises of each. I'll wait a little more until I know for sure that the break-in is complete. But my early impressions are that the Glen-Monica is not as tight in the bass or as precise in the soundstaging placement of instruments as my upsampling DI/O. It's musical, for sure, but the PRAT thing isn't as "boogie-worthy". The addition of the power supply cap absolutely improved things in that department, as well as the dynamics, so I would highly recommend that mod.

Enjoy,
Bob

[BobM]

Here's an update after a lot of time spent with the Glen-Monica. I did add the extra diode to the end of the string, and that made a subtle improvement. I also added a rather large (6800uF) poly-bypassed (.01uF) cap to the power connection on the board, and that improved both macro and micro dynamiocs.

Overall I prefer my opamp (LT1362) modded ART DI/O, but this is a very subtle thing. The Monica is just a bit sifter (leading edge transient speed) than the DI/O. And the DI/O definitely edges it out in macro dynamics.

However, we did an informal shootout last night at our audio club meeting between the Glen-Monica (everyone loved the case), a transformer output Di/O (using Edcor transformers right off the DAC chgip - a bit softer than the op-amp output version IMO), and a Benchmark DAC.

Well almost everyone agreed that the Benchmark was way more bright and forward than either of the other two. More detail and deliniation for sure. But on less than pristine recordings it was not enjoyable. Basic digital jitter feeling, like ants up my spine, and not very musical at all. Probably exactly what most reviewers like about it is its transparency and so called "truth".

The DI/O was far more musical, but lost out in brief A-B switching to the Benchmark due to the initial "wow" factor. Longer term listening might prove otherwise though.

The surprise of the evening was the Monica II NOS DAC that I recently built. Very musical and enjoyable on almost everything. Now I know it is also softer than my opamp LT1362 version of the DI/O (which I prefer overall). But in that system, last night, with the recordings we played (both audiophile and common commercial rock) it surpassed the other two DAC's in just about everyone's opinion. Perhaps it was the non-oversampled nature of it, or the internal reclocking - who knows.

Enjoy,
Bob

[albee]

Back to inverting phase . . .  does that mean your speaker cables should be reversed at one end?  Not sure.  Would you have to do that everytime you switch back to a different source?