joz Posted June 22, 2017 Share Posted June 22, 2017 Hi all , Ive got this Cambridge Audio Dacmagic2 that's been sitting here for a while . Bought it to use as a modding project but it has just sat here since. So does anyone have any experience or suggestions about what to do or what can be done ? also what would any likely mods bring ? Mod or sell? Link to comment Share on other sites More sharing options...
unclekanus Posted June 22, 2017 Share Posted June 22, 2017 Hi Joz, Just had a look on the Vasiltech site to see what chip they use in your dac but couldn't see a Dac 1. Is it a DacMagic 1 perhaps? Cheers Chris Link to comment Share on other sites More sharing options...
joz Posted June 22, 2017 Author Share Posted June 22, 2017 9 minutes ago, unclekanus said: Hi Joz, Just had a look on the Vasiltech site to see what chip they use in your dac but couldn't see a Dac 1. Is it a DacMagic 1 perhaps? Cheers Chris Dunno what your talkin about its a Dacmagic2 I should really check what I have Link to comment Share on other sites More sharing options...
krebetman Posted June 22, 2017 Share Posted June 22, 2017 Feeling lucky, punk Joz? https://lickham.co.uk/pdfs/dacmagic.pdf 1 Link to comment Share on other sites More sharing options...
unclekanus Posted June 22, 2017 Share Posted June 22, 2017 3 minutes ago, krebetman said: Feeling lucky, punk Joz? https://lickham.co.uk/pdfs/dacmagic.pdf Bingo! 1 Link to comment Share on other sites More sharing options...
joz Posted June 22, 2017 Author Share Posted June 22, 2017 3 minutes ago, krebetman said: Feeling lucky, punk Joz? https://lickham.co.uk/pdfs/dacmagic.pdf Ta some good reading there, not sure whether I could take on the mods? I wonder approx how much the bits would come too? Well I suppose the worst thing that could happen would be a bin worth of scrap! Link to comment Share on other sites More sharing options...
unclekanus Posted June 22, 2017 Share Posted June 22, 2017 (edited) Looks like a good project to me. You could always start out by swapping out the opamps which is easy to do assuming they are in sockets and not directly soldered in. I have a few old Burson discretes that you could have a play with if you like. Based on previous experience you should get a good improvement in sound quality with the Bursons. Edited June 22, 2017 by unclekanus Link to comment Share on other sites More sharing options...
joz Posted June 22, 2017 Author Share Posted June 22, 2017 8 minutes ago, unclekanus said: Looks like a good project to me. You could always start out by swapping out the opamps which is easy to do assuming they are in sockets and not directly soldered in. I have a few old Burson discreets that you could have a play with if you like. Based on previous experience you should get a good improvement in sound quality with the Bursons. May have to take you up on it, soonish! I must mention I have never done this stuff before Link to comment Share on other sites More sharing options...
unclekanus Posted June 22, 2017 Share Posted June 22, 2017 No problem. You're welcome to give them a go. As soon as I get my young bloke into bed I'll shoot a pm your way Link to comment Share on other sites More sharing options...
kukynas Posted June 22, 2017 Share Posted June 22, 2017 I wouldn't bother with it, you might end up paying more in parts for very little compared to what you could get instead these days, those os-con and elnas caps aren't cheap even today, this mod has been good improvement back in the days where TDA1305 has been standard and not many other options available. If I'm you I would either sell it as is or rip off the board and replace it with something better, there's still lots of options if you are looking for NOS type sound such as TDA1387, AD1862, PCM1702 etc as ready made kits... just to add comment from John Westlake Quote Yes, the TDA1305 was designed as a budget DAC, its not great TBH.... I never liked the sound, I originally designed the Cambridge Audio units for a different DAC but then discovered a design issue with the silicon so we had to change the DAC vendor at the last moment - the TDA1305 was the only other budget DAC available at the time. That said the CA offered really great performance / value for money so I can still sleep well at night.... 1 Link to comment Share on other sites More sharing options...
georgehifi Posted June 22, 2017 Share Posted June 22, 2017 (edited) 20 hours ago, joz said: Hi all , Ive got this Cambridge Audio Dacmagic2 that's been sitting here for a while . Bought it to use as a modding project but it has just sat here since. So does anyone have any experience or suggestions about what to do or what can be done ? also what would any likely mods bring ? Mod or sell? Download the service manual from here and post up the section from the d/a converter to the rca outputs (the analog stage) http://www.eserviceinfo.com/downloadsm/37510/cambridge audio_DacMagic 2.html Cheers George Edited June 22, 2017 by georgehifi Link to comment Share on other sites More sharing options...
georgehifi Posted June 22, 2017 Share Posted June 22, 2017 Don't worry did it for you, change the dual AD712 for a 2 x OPA627 on a dual Brown Dog adaptor board, do not get the 2 x OPA627 from ebay as they are all fakes, get them from RS Components or Element 14. Cheers George 1 Link to comment Share on other sites More sharing options...
Gieseler Audio Posted June 22, 2017 Share Posted June 22, 2017 (edited) Hi George, great info & advice! Hey what is with R27 & R30? Looks like they are trying to increase channel cross talk or maybe playing around with the imaging. Edited June 23, 2017 by Gieseler Audio Link to comment Share on other sites More sharing options...
georgehifi Posted June 22, 2017 Share Posted June 22, 2017 (edited) 2 hours ago, Gieseler Audio said: Hey what is with R27 & R30? Looks also like the trying to load down the impedance the dac sees, to 20kohm, as they go to ground also via another 10kohm Could try to lifting (disconnect) one side of of R27 and R30 and see how it sounds. If indeed it ruins the cross talk it can artificially give better centre image, but ruin the image width, ie outside the speakers I did this on a dac once to improve old recordings, just on the output with a 1kohm resistor (switchable in or out) from left to right and it made the old ping pong recorded cd's like Beatles, sound more like vinyl, with a fuller more defined central image, as vinyl has at best 30db channel separation. Cheers George Edited June 23, 2017 by georgehifi 1 Link to comment Share on other sites More sharing options...
Gieseler Audio Posted June 23, 2017 Share Posted June 23, 2017 Hi George - sounds like a good plan. It would definately be interesting to see how the image is effected after lifting those two resistors. OK Joz better get your soldering iron warmed up & remove the two original output ic's. Maybe fit sockets in their place so you can easily try a few different types there. I'm with a George tho on the OPA627 - excellent choice. This thing is about twenty years old now so maybe time to replace all the electrolytic caps in the PSU & around the op amps too. Panasonic FM or FC types are pretty good & reasonabley priced. Buy all the parts from RS or Element14 & then you know they will be genuine. 1 Link to comment Share on other sites More sharing options...
joz Posted June 27, 2017 Author Share Posted June 27, 2017 On 6/23/2017 at 8:30 PM, Gieseler Audio said: Hi George - sounds like a good plan. It would definately be interesting to see how the image is effected after lifting those two resistors. OK Joz better get your soldering iron warmed up & remove the two original output ic's. Maybe fit sockets in their place so you can easily try a few different types there. I'm with a George tho on the OPA627 - excellent choice. This thing is about twenty years old now so maybe time to replace all the electrolytic caps in the PSU & around the op amps too. Panasonic FM or FC types are pretty good & reasonabley priced. Buy all the parts from RS or Element14 & then you know they will be genuine. Thanks Clay, I almost wonder whether I should just grab one of yours. But.... @unclekanus I may just take you up on lending a hand with having a play with this thing, but I'm gonna be tied up until mid /end July. Link to comment Share on other sites More sharing options...
unclekanus Posted June 27, 2017 Share Posted June 27, 2017 No worries Joe, let me know when you're ready to be untied... Link to comment Share on other sites More sharing options...
rockeater Posted November 12, 2019 Share Posted November 12, 2019 On 23/06/2017 at 6:09 AM, Gieseler Audio said: Hey what is with R27 & R30? Looks like they are trying to increase channel cross talk or maybe playing around with the imaging. These things are designed by engineers, not audiophiles, and no engineer would ever want to increase channel cross-talk. Or play with imaging for that matter. I think this might be done to feed out of phase signal to the negative input of an op-amp to reduce/cancel distortion. Anything present on one and not on the other will be cancelled and not present on the output. Commonly done. BTW. I am fixing one of these and need input section diagram. Anyone has it by any chance? cheers Roman Link to comment Share on other sites More sharing options...
Guest Muon N' Posted November 12, 2019 Share Posted November 12, 2019 (edited) Seeing as these are V-out DAC chips why not just do away with the op amps completely and take the signal from v-outs through some quality caps to RCA sockets. Edit: or use line transformer instead of caps, just need an appropriate resistor load on the primarys and a r/c filter on the secondary. Edited November 12, 2019 by Muon N' Link to comment Share on other sites More sharing options...
rockeater Posted November 12, 2019 Share Posted November 12, 2019 1 hour ago, Muon N' said: Seeing as these are V-out DAC chips why not just do away with the op amps completely and take the signal from v-outs through some quality caps to RCA sockets. I am not an engineer so I cannot answer with any authority but reducing the noise/distortion would be one reason. I would get rid of RCA sockets and use XLRs as most DAC chips for a long time now are balanced and bastardising them with single ended output is just a travesty. Link to comment Share on other sites More sharing options...
Guest Muon N' Posted November 12, 2019 Share Posted November 12, 2019 So you don't know and are assuming why it can't be done with success. I would suggest that op amps are cheaper than quality line transformers or high quality capacitors, is the main reason. Look up voltage out DAC's using line transformers, the same can be done using capacitors in place of transformers. I along with a huge amount of other guys did line transformer output replacing conventional op amp output stages, there is a big thread on diya using a cheap kit based on the CS4397, the thread is dominated by us all using audio line transformers. I ended up using cinemagCMOQ-2H transformers in my kit. https://www.diyaudio.com/forums/digital-line-level/137976-experience-diy-dac.html Same can be done successfully with AKM v-out dac chips. So, just maybe the same can be done with this v-out dac chip. Link to comment Share on other sites More sharing options...
rockeater Posted November 12, 2019 Share Posted November 12, 2019 16 minutes ago, Muon N' said: So you don't know and are assuming why it can't be done with success. Depends on what you mean by success. What is a success to you or some DIYers is not really an achievement for an engineer. Engineer knows what can or cannot be done and why. I am merely a technician and I know my limitations. One thing I can tell you is that in my book line transformers are silly thing to do on an output. The only reason one would ever do them is for impedance matching and should be avoided whenever possible. Capacitor out of DAC might work for you and for your system but not in a commercially sold equipment. An item you buy in the shop should work with any system it is connected to. The mere fact that some guy has modified some item by fitting Delund capacitors and it sounds good to him, does not mean anything. If the product is so good, he should make 500 of them and see if anyone will buy them. Then it is a success. 1 Link to comment Share on other sites More sharing options...
Guest Muon N' Posted November 12, 2019 Share Posted November 12, 2019 (edited) 1 hour ago, rockeater said: Depends on what you mean by success. What is a success to you or some DIYers is not really an achievement for an engineer. Engineer knows what can or cannot be done and why. I am merely a technician and I know my limitations. One thing I can tell you is that in my book line transformers are silly thing to do on an output. The only reason one would ever do them is for impedance matching and should be avoided whenever possible. Capacitor out of DAC might work for you and for your system but not in a commercially sold equipment. An item you buy in the shop should work with any system it is connected to. The mere fact that some guy has modified some item by fitting Delund capacitors and it sounds good to him, does not mean anything. If the product is so good, he should make 500 of them and see if anyone will buy them. Then it is a success. So you agree that it is a decision based on cost and profit, at it's basic fundamentals....mass marketability. Edit: at this point I need to point out that AMR (Thorsten Loesch, designer)use transformers in the output stage of their DAC, and Gieseler Audio (Our own talented Clay Gieseler, designer) Uses transformers in his very good and very affordable DAC's. Maybe that book of yours needs revision. Edited November 12, 2019 by Muon N' Link to comment Share on other sites More sharing options...
rockeater Posted November 12, 2019 Share Posted November 12, 2019 2 hours ago, Muon N' said: So you agree that it is a decision based on cost and profit, at it's basic fundamentals....mass marketability. Yes and No. Marketability yes but meaning that an item must work in any system with any input or output impedance. Transformers, being devices that transfer electrical energy by means of induction in secondary circuit have tons of disadvantages, with very little to show on advantage side. In audio, they are mainly used as matching impedance of tubes to speakers, (because tubes are not really suitable for audio, even though a lot of companies use them for marketing reasons mainly) and for some other minor duties (Toslink, fake balanced circuits etc). 2 hours ago, Muon N' said: Edit: at this point I need to point out that AMR (Thorsten Loesch, designer)use transformers in the output stage of their DAC, and Gieseler Audio (Our own talented Clay Gieseler, designer) Uses transformers in his very good and very affordable DAC's. The fact that some competent people are doing something does not make it right or good. C.E.C. makes belt driven transports which is a an idea as silly as it gets and some people even buy them and swear by them. But it is still silly and substandard with all the disadvantages of it and nothing to show for it but high price and reduced usability. 1 Link to comment Share on other sites More sharing options...
Guest Muon N' Posted November 12, 2019 Share Posted November 12, 2019 (edited) It appears you see things that are not there, so I'll have to remain in a state of disagreement on this. Edit: just to add a couple more! PSAudio use output transformers in their top of the line Direct Directsteam $9k DAC, and Linn also use them in their $37K Klimax DSM streamer. Edited November 13, 2019 by Muon N' Link to comment Share on other sites More sharing options...
Recommended Posts