Amc 8 dac
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zingo
Posts: 11,258
Howdy friends! I have a lowly AMC 8 DAC which works pretty well and I have no complaints about. Does it have the best SQ on the market? Nope. Does it sound pretty good and cost me next to nothing when I originally got it? Yup. We audio DIYers know that you can upgrade the SQ of a component by upgrading the signal path. You can also gain some improvements by upgrading power filtering or anything that may be sub par or inadequate. Has anyone modded or upgraded a DAC? I don't think I have any specific goals here, I just like to tinker and increasing SQ is always a plus in my book. The attached pictures are: the DAC in all its underwhelming glory, two picture of the main board, the connections board, and the power board.
Post edited by zingo on
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That chip with JRC on it, I'm guessing it's an opamp. Maybe look at replacements. Otherwise, why spend time on money without knowing the outcome in advance?
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I would google that chip. I can't red the numbers from the pic, but if you can find it at onsemi, or digikey you could pull the data sheet. I am sure it is a 2 channel chip. It has to be. Most likely you can drop a BB/TI2134 in their, but I am just guessing not knowing the voltages. The Chip is only about $3:)That chip with JRC on it, I'm guessing it's an opamp. Maybe look at replacements...
BenPlease. Please contact me a ben62670 @ yahoo.com. Make sure to include who you are, and you are from Polk so I don't delete your email. Also I am now physically unable to work on any projects. If you need help let these guys know. There are many people who will help if you let them know where you are.
Thanks
Ben -
From the pics it looks like your options are very limited .It appears that the opamp is operated from a single voltage supply (+ only no -).This is not Ideal and many premium op amps will not play nice with single rail supplies or atleast will not be at their best.You could add a dual voltage supply and use a good opamp but IMO this very basic unit isn't worth the trouble as the digital section is not S0TA by any means.On a positive note they did use a 75ohm BNC connector.;)
I can't see the number on the regulator on the back board might it be an LM7812?
Im assuming the DAC chip is surface mounted on the bottom?Testing
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From the pics it looks like your options are very limited .It appears that the opamp is operated from a single voltage supply (+ only no -).This is not Ideal and many premium op amps will not play nice with single rail supplies or atleast will not be at their best.You could add a dual voltage supply and use a good opamp but IMO this very basic unit isn't worth the trouble as the digital section is not S0T by any means.On a positive note they did use a 75ohm BNC connector.;)
I can't see the number on the regulator on the back board might it be an LM7812?
Im assuming the DAC chip is surface mounted on the bottom?
I'm guessing yes, 7812, as the mainboard is regulated by means of a 7805.
Good point on supply rails. It's best to measure how the opamp operates in the current setup. -
Yeah the 7805 will be for the dac/logic chips and I suspect the regulator on the backboard is for the op amp as well as a pre reg for the 7805.as the mainboard is regulated by means of a 7805.Testing
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If it's anything like the AMC CDPs, the diodes of the power supply
would make a difference. Look up the part numbers and replace with
FREDs(fast recovery diodes). This will help the bass output."The legitimate powers of government extend to such acts only as are injurious to others. But it does me no injury for my neighbour to say there are twenty gods, or no god. It neither picks my pocket nor breaks my leg." --Thomas Jefferson -
Zingo, I use one of those in my office rig. All the weight comes from the face plat and the case-LOL.
I paid little to nothing for mine and it's decent. Better than most lower to mid level players. My Adcom GDA 600 smokes it and we put it up against a Rotel RCD 1072 and it pretty much smoked it as well.
They have next to nothing internally and are use a bit stream conversion chip if I remember correctly. It is quite nice for office duty and has lots of inputs and is much better than most sound cards.
BUMP
H9"Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul! -
Yes it appears to use Phillips bitstream DAC and I/O chips.and are use a bit stream conversion chip if I remember correctly.
Zingo,that chassis is quite nice and would be a good platform to install one of the excellent DIY dac boards available should you want to do that some time.Similar to what I did with this.
http://www.polkaudio.com/forums/showthread.php?t=72911
The board I used is not available but here is another option.
http://www.twistedpearaudio.com/digital/buffalo.aspxTesting
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