DDDAC 1543 MkII USB

DDDAC 1543 MkII USB

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While looking for a case for my compact chip amp I came across the hammond 1455 enclosures.

These extruded cases have internal grooves to hold circuit boards, which by happy coincidence hold a DDDAC board perfectly...

A plan was born....

Here is what I came up with

 

 

Step 1  The single module DAC

The case although width wise is right, is not available with the correct height for a DDDAC module. However in the larger widths it has a slide off panel. This I took a drill, junior saw and a set of miniature files to to "open up the bonnet" 50's Hot Rod style.

I fashioned holes the right size and shape for the DAC's cooling tower.

From light alu sheet I cut and brushed a strip which folded makes a vanity screen/shield for my chips. I am going to work on the shape of this further.

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For Stage 1 I deliberately placed the DDDAC module to the front of the case.  This left space for more modules to be added in future.  As you can see from the picture, the measurements just about allow for three DDDAC towers plus the USB receiver. 

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Later, in August 07 I added a second DDDAC tower. Doing so was easy-ish.  I just drilled, sawed and filed out a second Hot Rod style hole. 

 

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The pictures show the construction of the DDDAC pretty well.  Generally I am pleased with the overall look.  However squeezing a third tower in that case is going to be a little tight.  I am pretty sure that i am going to change case styles when I get to that stage. 

I suppose I must make my first admission...

Some clumsiness, I had an issue with clearance in my tower. In fact I have mounted the usb module too high. I tried to shorten the highest point on the board, The metal tag on the lm8706. Of course I broke it.

Hidden in those pictures is an off board lm317 which I rigged up to replace the 7806. Works fine though getting the right values from my resistor collection was a challenge! If I am going to squeeze in a third module, I would have to lower the usb section and fix up the back plate.
I am pretty sure that i am going to change case styles when I get to that stage. 

 

My first listen was with a single DAC tower installed.  Immediately I was delighted with this DAC. It replaced my Cambridge Audio DAC1 (OK perhaps a dated piece of equipment) and was sweeter, more musical, more definitely more dynamic. I cant really express by how much, but a lot!

I am using it with a Skynet 8080 SMPS. I get these at real good prices via an EBay contact. It seems a good PSU. NUUK at Decibel Dungeon recommends it for chip and D class Amps. It seems to fit the DDDAC well. I was on a budget and I don't think I did badly.

I used Sonicaps bypassed with Vishay 1837 0.01ufcaps on the output. This seems to give me a sound I really like. This plays through 4 a gainclones into my Mission 753's in a passive bi-amp setup.

I am gradually re-ripping my music collection to loss-less. The difference in quality is suddenly transparent. Mpegs don't cut it with this DAC. You know instantly you are listening to compressed music. Loss-less on the other hand sounds amazing. The conversion to loss-less seems a never ending task. I keep listening and re-listening to every one each track.

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So how does it sound with a second tower?


Second admission. In my excitement to get the second stage up and running I tried out the dac before I had completed the mod to the case to allow the lid to be put on.

I auditioned the dac first with one stage then with the second. I immediately got more detail with the second stage installed. however I found the top end was a bit confusing, it seemed as if there was too much detail. The top end also had become hard sounding. Dynamics seemed to have suffered as well. I racked my brains for a while as to what could have caused this. I reckoned it was either the change to metal film resitors in the IV stage or the system needed to bed in.

I left it powered up for a day and a half (My girlfriend expects to see me occasionally) and came back with less tired ears.

Still the top end was the same. The dynamics seemed a little better. My ears were telling me though that the extra detail was not coming from the recordings. I had a better idea where the problem lay.

I got to work on the case lid. Cutting out the aperture for the tower using my bench press drill and the miniature files. Popping it on the sound immediately and dramatically improved. The noise floor dropped back down and the dynamics that I love from the dddac reappeared. Most dramatic of all was the top end detail. High hats became softer, more realistic and beautifully detailed.