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-   -   Dacmagic Mods (http://www.diyaudio.com/forums/digital-line-level/40594-dacmagic-mods.html)

Blue_Max 8th September 2004 03:23 AM

Dacmagic Mods
 
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.

JohnW 8th September 2004 10:17 AM

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

Blue_Max 8th September 2004 04:43 PM

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.

Nuuk 12th September 2004 02:36 PM

B-M, I am looking at these things the other way round!

I have a DAC and am looking for a Freeview box with an SPDIF out. Do you know of any? ;)

pinkmouse 12th September 2004 03:10 PM

Nuuk

There is a Humax model, (that has a built in hard drive used as a PVR )that has optical output for about £140, but I'm not sure about electrical. Perhaps some of the expensive Sony units might?

Blue_Max 12th September 2004 03:14 PM

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 12th September 2004 05:29 PM

Thanks for the answers guys. Anybody want a cheap Pace box? :o

Blue_Max 12th September 2004 05:33 PM

Quote:

Originally posted by Nuuk
Thanks for the answers guys. Anybody want a cheap Pace box? :o
Does it come with a S/PDIF digital output?! :D

Nuuk 12th September 2004 05:38 PM

Quote:

Does it come with a S/PDIF digital output?!
No - that's the reason for wanting to upgrade to one that does have SPDIF! ;)

brianuk 12th September 2004 05:42 PM

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&b...3,,btdigitaltv
(£65)


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