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Post by bennyboy on Apr 16, 2007 3:47:56 GMT
I've got a pair of duals I bought direct $140. I had them in a MSB link dac and they sounded incredible, a few months later I got a Entech dac. The entech only needs one op-amp. I installed the Burson in the Entech and once again the sound was incredible! This morning my arm rubbed the side of the entech and I noticed it was very hot! I opened it up and found burns on the board all around the rectifier. Turns out the descrete op-amp need a lot of juice. At this point I could put a bigger heatsink on the 317 but I also noticed some of the caps are bloating. So new Panasonic caps in the Entech and the return of the AD825's. The MSB had no problem with the Burson's(as it was on for about three months). I've sold the msb and I need money more than extra op-amps. If you want them? There in mint cond and I'll ship sell/them for $110. Benny. This pic shows one of the two. farm1.static.flickr.com/242/459157204_130505af7f_o.jpg
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Sol
100+
loves motorcycles !
Chief Technical Numpty
Posts: 135
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Post by Sol on Apr 16, 2007 21:55:07 GMT
Check your PMs Benny
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Post by bennyboy on Apr 18, 2007 3:42:02 GMT
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Post by PinkFloyd on Apr 18, 2007 10:50:03 GMT
Join the club man, am totally skint for the first time in years
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Sol
100+
loves motorcycles !
Chief Technical Numpty
Posts: 135
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Post by Sol on Apr 20, 2007 21:55:21 GMT
BennyBoy .. drop me an email / PM - you can consider them sold ... I can see the beginnings of a DAC mod session coming on.
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Post by bennyboy on Apr 21, 2007 4:17:18 GMT
Done, Thanks.
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Post by PinkFloyd on Apr 21, 2007 23:13:06 GMT
You couldn't be buying from a nicer guy Sol, let me know how the modules perform in your DAC Mike.
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Deleted
Deleted Member
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Post by Deleted on Apr 22, 2007 1:25:32 GMT
Re Output Buffers Has anybody with a transistor tester ever tried to make their own ? A very good buffer can be made using the schematic for the LH0002 I.C. Replace the 2 ohm emitter resistors with 4.7 ohms Use a transistor tester matched pair of around 300-350 BC549 and BC559(match VBE too, if possible). Use another matched pair of around 400-450 HFE BC549 and BC559 for the output devices. The 5Kohm resistors should be replaced with 2N5484 FETS (or similar) that have a drain current around 3mA with drain and gate connections used , but a 100 ohm resistor inserted between source and gate connections.(often used in Elektor audio designs) I have been using these buffers in an old Marantz CD65 as a plug in module for many years,with extremely good results. They work even better if included in the feedback loop of the preceeding opamp. Use a 47 to 68 ohm series resistor in the output. The FETs' constant current, keeps the buffer far more linear in it's operation. I have also used them in a preamp with excellent results. They are time consuming to build, and you really need at least 20 of each device to get some reasonably matched pairs. Incidentally , Silicon Chip magazine also used discrete versions of the LH0002 in a Video Switcher, but without the FET. SandyK
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Post by bennyboy on Apr 22, 2007 15:41:44 GMT
Excuse me! Your stepping on my add! I'm selling stuff here! Put your post in the correct area. Re Output Buffers Has anybody with a transistor tester ever tried to make their own ? A very good buffer can be made using the schematic for the LH0002 I.C. Replace the 2 ohm emitter resistors with 4.7 ohms Use a transistor tester matched pair of around 300-350 BC549 and BC559(match VBE too, if possible). Use another matched pair of around 400-450 HFE BC549 and BC559 for the output devices. The 5Kohm resistors should be replaced with 2N5484 FETS (or similar) that have a drain current around 3mA with drain and gate connections used , but a 100 ohm resistor inserted between source and gate connections.(often used in Elektor audio designs) I have been using these buffers in an old Marantz CD65 as a plug in module for many years,with extremely good results. They work even better if included in the feedback loop of the preceeding opamp. Use a 47 to 68 ohm series resistor in the output. The FETs' constant current, keeps the buffer far more linear in it's operation. I have also used them in a preamp with excellent results. They are time consuming to build, and you really need at least 20 of each device to get some reasonably matched pairs. Incidentally , Silicon Chip magazine also used discrete versions of the LH0002 in a Video Switcher, but without the FET. SandyK
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Deleted
Deleted Member
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Post by Deleted on Apr 22, 2007 20:59:00 GMT
bennyboy Seeing you are a technical type , I thought that you might be interested in a way to make some buffers .Not very many of the forum members would be able to do what is needed,that's why I didn't put it in as a normal post. Who knows, perhaps you could even sell some ? SandyK
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Post by bennyboy on Apr 25, 2007 4:09:23 GMT
SOLD to Sol!
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