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My Beresford DAC project

A

Ant

pfm Member
Back to the beginning - For my PC based music I had a Beresford TC-7520 DAC doing the duties, a week or so after the purchase I opened it up for a looksy. Within a week I'd replaced the usual Burr-Brown PCM1716 DAC chip for the Wolfson WM8716, DAC analogue caps for Muse KZ's, direct output op-amp to LM49720HA tin hat and LM4562NA for the variable, together with Muse Bi-Polar for coupling. That lasted a few weeks and then I thought about linear PSU's, one for 5v and one for 12v, a pair of TeddyRegs became available and that was it... No going back.

I didn't want a 'separate' box for the PSU's nor did I want to buy a pre-built case, I wanted to do it DIY style - a quick play and I came up with this as an idea and it stuck:

final.jpg



To the left on the render is the standard size of the 7520, to the right is my prospected case.

That was it, I was off.... I gave myself a few days off so my desk could become a workshop/mill/dump. 3mm aluminium sheet was ordered pre-cut to my requirements and Oak was in hand, so on I went with the drilling/routing/cutting/filing/sanding.


First up the 'desk' press:

bcase001.jpg



Next the materials (on the left):

bcase002.jpg



A few markings:

bcase003.jpg



The Oak was precision cut top and bottom to allow the 3mm plate to fit flush (thanks dad):

bcase004.jpg



Top and bottom fixed:

bcase005.jpg



At this point I'd like to add that I required the 'whole' case to be fixed with zero glue or permanent fixings, ready for disassembly come paint time.

Braces in:

bcase006.jpg



Front panel fixed, 5mm overhang all round:

bcase007.jpg



Bottom 'peppered' ready for all the M3/M6 allen bolts:

bcase008.jpg



TeddyRegs in place using the base plate as a heat-sink.

bcase009.jpg



Drilling the rear panel ready for filing the square USB/Toslink/Fused-switched IEC and 6 RCA's:

bcase010.jpg



Almost there:

bcase011.jpg



Ready for drilling the LED holes:

bcase012.jpg



All fixings are black M3 allen bolts on the underside, M6 for the feet and trannys and black screws throughout.

I painted the case myself and not blowing my own but it's flawless - 8 etch primes and 12 satin blacks later and it's mint, I am pleased. Just the Oak to sand and oil and the laser cut decals to apply but here it is:

bcase013.jpg



The back:

bcase014.jpg



Old on top, new below:

bcase015.jpg



Now for the inside the box...


After my initial plan of using a 18.5v-0-18.5v toroidal was thrown out and 2 separate transformers were recommended:

I have a 9v EI tranny centre tapped -- 2 x 8A Hexfreds -- Kendeil 6800uF -- TeddyReg set to 5v supplying the Wolfson DAC chip.

15v EI tranny centre tapped -- 2 x 8A Hexfreds -- Kendeil 6800uF -- TeddyReg set to 12v supplying the op-amps/leds.

It's early days but wow, what an improvement - Super wunderba, I'm chuffed to bits.


A few piccys:

bcase016.jpg


bcase017.jpg


bcase018.jpg



All I need to do is wire-wool the Oak, oil and fit the laser cut decals and the jobs a good one.




I would like to thank misterc6 (Malcolm) for helping me with the TeddyReg resistor values, without him and his knowledge I would have been truly stuck, also to Martin Clark and his super site acoustica for all the info on PSU's.


Well, that's me done (for now)


Cheers folks,
Ant
 
Uncanily close to the box design I just ordered ally for today, very timely :) what are the fixing you have used for the front panel?
Stefan
 
Very nice job you did there! I might copy some of those mods..

Just a quick question, - Did you ever think of changing those non polar coupling caps with film caps instead? I did that in my Caiman using some mylar film speaker caps (in parallel with some Wima FKP1 foil and film popyprop bypass caps to warm up the sound). Its pretty bulky, but doing that, you eliminate the hysteresis the electrolytic caps produce and the detail becomes better (things are less smeared sounding). Its a very good upgrade, but can be pricey as you need quite a lot of high value film caps. I had some spare mylar film caps from some Magnepan crossover boxes available to use so it did not cost me much (only the price of the Wimas from Maplin)

I note that Beresford is coming out with a new DAC soon (the "bushmaster") which is a DC coupled design and uses no coupling caps. An technical friend of mine told me to be a little vary though s DC coupled designs can sound too dry. So if I buy one I will not be selling my modified caiman until I hear the Bushmaster first.

Cheers,
Colin
 
Well done Ant, superb job!

Note the novel approach to mounting the psu capacitors!

malcolm
 
Brilliant presentation, what does it sound like?

I think you should fit a clear top so everyone can see your work, or a camera showing the insides.....Only joking.
 
Swap those Hexfreds for Qspeed diodes and add a choke to the PSU and you're done. ;-) That looks awesome, what an upgrade.
 
Hi, Ant

DON'T wire wool the oak any bits left will react with the tannin in the oak and go black, use a scotchbrite pad, that’s what I use.


Pete
 
Keep coming back and looking again and again, such a nice job. REALLY want to know where you got the fasteners for your front panel from......pretty please....

Stefan
 
Thanks all for the thumbs up.

I'm very pleased with the result, it took a while but I think it was worth it. I spent many many hours searching the web for ally sheet and fixings only to find that it was all available on my doorstep.

The aluminium was cut to my requirements 5 minutes from my house by Locate Supplies who did a stellar job for very little cash and was exact in measurements. They also have a waterjet which I'll bear in mind for future projects as the bevelling/drilling/chamfering/filing by hand took a long time to get a perfect result. Well worth having a look at their site if you're planning a build of any nature.

The Oak came from the wood-yard 10 minutes down the road, cut to square and my dad routered the 3mm recess with precision (top job Dad)

The fixings were a pain as I wasn't sure what I wanted - allen/torx/countersunk/flat/button/shallow-head/security/snake-eyes/PZB/stainless/anodised/black etc etc... you get the idea. Luckily Bapp is also 5 minutes from my house and unbeknown to me, they quite literally stock and sell pretty much any fixing you can think of. They even gave me access to their gigantic stores so I could peruse at my leisure to which the owner/director came down suited and booted to help rummage through the boxes - now that's customer service. I still couldn't decide what I wanted so I took 30 of pretty much everything and would decide when I came to put the case together. I was expecting a big bill but it came to under a tenner for the whole 5kg bag of screws/bolts.

The front fixings were a different matter - I spent hours upon hours searching the web for the 'exact' thing I wanted, I just couldn't find them anywhere... Then I found the blighters... yep, 5 minutes from my doorstep.... I feel a trend coming on ;) I'm not saying where they came from or what they are - it's my little secret, although if you do try to find them - good luck :D

The switch/socket holes were drilled 2mm oversize to allow for bit chattering with enough overhang to align without the worry that they wouldn't line up.

I must say I'm a self confessed perfectionist so the smallest mistake would have rendered the case in the bin, luckily everything went as planned and there isn't a single error anywhere - Relief :cool:

As for swapping the caps and diodes - I'm quite happy to leave this one for now and enjoy the music.

Pete MB&D - Many thanks for the tip.



So that's it, thanks again folks
Ant
 
Lovely work and attention to detail in what look like challenging workshop conditioms. :D
Top job to be proud of.
Tony
 
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