Dacmagic Mods

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Any Dacmagic users here?!
An illustrated 3-page article in the Jan 1999 edition of Hi-Fi News & Record Review covered modding a Dacmagic II Mk 2.
It can be downloaded as a .pdf file at
http://lickham.co.uk/pdfs/dacmagic.pdf (922k)
Kit of parts mentioned in the article is no longer available. But should be able to source them from RS, Farnell, AD, etc.

I am sort of tempted. Has anyone tried modding one of these?
With later designs such as M-Audio SuperDAC 24/96 and ART DI/O available is it still a worthwhile mod?

Model History
DacMagic was designed by John Westlake, former Pink Triangle Tech, and digital conversion is accomplished by a pair of Philips TDA 1305 "18-bit" hybrid chips (the Naim CD 3.5 uses one).

DacMagic 2: Dual Philips TDA1305 hybrid DACs with symmetrical dual differential circuitry. Three separate transformers feeding 19 independent power supplies. DacMagic 2 is an improvement over the DacMagic 1.

DacMagic 2i: Many significant improvements. Design revisions resulted in reduction in distortion by as much as 50 per cent, gold-plated printed circuit boards and connectors, and better quality low-noise transformers.

Dacmagic 2 Mk II: same as Dacmagic 2i but with AD 712 JN output chips (about £1 each).

DacMagic 3: was the last of the series.
 
In the ending “credits” of the article, Andrew Harrison thanks me – unfortunately, I’ve never met or spoken with Andrew Harrison – not to mention know anything about the article before it was published.

Changing the electrolytics to better quality types such as OSCON’s will always help, but don’t waste money changing C115, the 100n SPDIF input Cap to Polypropylene as recommended in the article.

Unfortunately, the designs biggest weakness is the TDA1315 – the SPDIF input receiver. The TDA1315 has very poor jitter performance – despite claims otherwise from Philips, by the time this was realised; the front panels and casework had already been manufactured (the front panel has LED’s for sampling rate and copy protection). Changing the design to the better performing CS8412 was not an option, as the CS8412 has no direct method to drive the front panel sampling rate LED’s – and the budget was already very limited (original retail price was £149).

If possible, modifying the unit to “clock-lock” with the transport will bring enormous improvements – then the quality of the Dac becomes the limiting factor.

The first pre-production version of the design used Burr Brown devices (I seem to recall the PCM1710), I much preferred the sound of these DAC’s over the TDA1305’s, however the Burr brown DAC’s had a STUPID design fault that prevented them being used in dual differential mode.

The Burr Brown devices internal mute circuit was designed to detect all zeros – and not “change of data”. During “Mute” in dual differential mode, one Dac receives “all zeros” – and the second Dac “all ones”. This meant one side would go into Mute – while the other side still operated – resulting in DC offset on the outputs during “Mute”. As a result was that I was forced into using the TDA1305 as there where no other good performing “budget” DAC’s on the market at the time. Still many liked the sound of the TDA1305 – but Naim using it their CD3.5 is really stretching it way too far – these are BUDGET DAC’s – limited by there internal digital filtering. They have a very muddled Bass heavy sound, with poor sound stage – possibly, why Naim selected them?

My best DAC design for Cambridge Audio was the HDCD ISOmagic – if you can get hold of one, then it’s a unit worthy of modifications!

If you have an ISOmagic or CD4SE - don't let go of them - or you will find yourself regretting it later - just ask those who have...

John Westlake
 
It is great to get a response from the designer himself. :) Thank you.

Modern CDPs may have better DACs built-in but many mid-range models still appear to gain from an external DAC. Unfortunately with the exception of expensive DACs from Musical Fidelity, hi-fi industry appear to have given up this market segment.

With the ever increasing popularity of universal DVD players/recorders, FreeView and satellite boxes, there might still be a viable niche market for a modern DAC that can accept outputs from different sources and function as a central unit between a stereo amp.
 
Many sets claim digital outputs but only few have electrical and not optical. I use a Nokia Mediamaster 221T. It has electrical digital output. Also a card slot for the TopUp TV. Many boxes do not. Nokia Mediamaster is not the cheapest but has a good reputation. I live in a fringe are but it picks up all stations. Price was down from £130 to £90 last time I saw.

Have a look at
http://www.digitalradiotech.co.uk/freeview_rx.htm
http://www.radioandtelly.co.uk/freeview.html
http://www.radioandtelly.co.uk/cgi-bin/forum/YaBB.pl
http://forum.digitalspy.co.uk/board/index.php
 
Nuuk, go for a netgem!
I paid £50 from macro and even came with the keyboard, it can do usb too and has modem built in, very clever.

NOTE:Sound isnt great for music and probly wont be for any freeview box but films on tv have been great piped into my sony optical in and surround generated, in fact Messiah on tv the other week was great, made me :bigeyes: at times!

BT also sell it rebranded.

http://www.netgemdirect.com/ (shows £130!)

http://www.shop.bt.com/invt/011613&bklist=icat,3,,btdigitaltv
(£65)
 
NOTE:Sound isnt great for music and probly wont be for any freeview box

I can confirm that sound out of a Freeview box isn't great but I have been told by somebody that I trust that when the signal is taken from an SPDIF and played through a decent DAC/hi-fi, it is actually better than DAB.

Does that Netgem have an electrical connection to a DAC or an optical? Specification is very sparse on those links. :xeye:

Swap one for a GC? I wish that I could turn them out for that sort of money! ;)
 
Yes u r spot on, theres a good uk site that compares bit rate of DAB and freeview. DAB is awful (rip off) Britain has the worst bitrate in the world for DAB, I wouldnt have one if u paid me. Sky and Freeview are siginificantly higher.

DAB's are so expensive too and then u get poor quality, cant believe its happening!

Nuuk -
I hope its optical cos thats where its plugged into my Sony! :cool: ;)

If you want good radio buy a good FM, nothing beats it in the UK - yet.

But the netgem is ok, i listened to the proms last night (just to test it u understand!) and it was fantastic with the surround on, not sure my scottish neighbours here in aberdeen appreciated a bit of "da da da da da da daaaa daaaaa (altogether now) Land of Hope and Glory...". They arent Brits theyre Scots.

Oh and then the conductor did it all again, so i had to turn it up some more :hot:
 
Sound (or rather the sound signal) from Freeview is indeed better than DAB. That is because BBC sqeezed too many channels into DAB and lowered the bit rate. See bit rate table at
http://www.digitalradiotech.co.uk/index.htm#bit_rate_table

S/PDIF digital output is marginally better than optical. But you will notice it only in genuine hi-fi applications such as between a CDP and a DAC. Not with Freeview.

If you buy a DAC with S/PDIF digital output and optical, you would want to use S/PDIF for CDP or DVD and optical for Freeview. Very few DACs two S/PDIF digital outputs.

If you want to know more about the DAC world come over to HiFi Choice Forum at http://forum.hifichoice.co.uk/
 
If you want good radio buy a good FM, nothing beats it in the UK - yet.

Don't worry Brian - I have my trusty (modified) Nad 412 here and it is very good (hence I was totally unimpressed by the Freeview sound).


But the netgem is ok, i listened to the proms last night (just to test it u understand!)

No need to apologise. The Proms are an excellent source of music and a good excuse to feel good about being British! ;)

I will keep my search down to a Freeview box with an electrical output to my DAC.
 
TDA1305 I/V, biasing its internal op-amp into class A

I have a Dacmagic 2 to which I have made many modifications and with which I am very happy. However there is one modification which I am keen to try but about which I have reservations. It is biasing the internal TDA1305 I/V op-amp into class via a constant current source on its output. My reservations are to do with how much this might raise the temperature within the TDA1305.

Has anyone tried this with the TDA1305?
How much current draw was introduced?
What were the results with regard to temperature?

Thanks for any help,
Tim.
 
Significant gains in the performance can be made by using a device such as Monarchy Audio DIP 48/96 Upsampler between the DAC and the source.

DIP 48/96 Upsampler isolate the DAC from the transport (blocking hum and RFI), boosts incoming signal, de-jitters (timing errors) and then re-clocks using its high precision clock. It also dithers, increasing the bit rate from 16 to 24 bits and then upsamples the frequency from 44.1kHz to (user selectable) 48kHz or 96kHz.

http://www.monarchyaudio.com/upsampler.htm

An externally hosted image should be here but it was not working when we last tested it.


Price from Wollaton Audio, the UK Distributor, is £399 plus delivery charges. :eek:

It is now on special offer for USD299 including shipping. Even abroad to UK! They will wire it FOC for UK voltage, if you ask.

VISA exchange rate was 2.7% below market rate and I paid £160.64p in all :)
Free delivery, no import duty, VAT or admin charges. :)
If anyone want to know how to go about buying one, PM me.
 
Soft recovery diodes made a big improvement on my friends DACmagic

Possibly one of the biggest improvements we got out of all kinds of tricks were replacing all the diodes to I think BYT53.
Be careful with plugging the digital input in and out. Always switch off if ever comparing cables. The dacmagic easily popped the SPDIF CD input buffer....
 
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