Finally got my Xmas give away buffers rigged up (thanks Ray for relinquishing your allocation!).
Using them to replace the opamps on a JLE Sylph D200 3255 amp. They feed a 600:600 signal trafo for the SE to diff conversion.
Using one dual rail PSU but I made an little auxillary filter board to afford the channels maybe a bit more separation.
Set at 15v, offset is negligible.
Early days, but it's working!
Using them to replace the opamps on a JLE Sylph D200 3255 amp. They feed a 600:600 signal trafo for the SE to diff conversion.
Using one dual rail PSU but I made an little auxillary filter board to afford the channels maybe a bit more separation.
Set at 15v, offset is negligible.
Early days, but it's working!
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Neat application! I was looking at those little signal trafos on Aliexpress and wondering how good they sound. What’s your opinion? Neat to see you bypassed the on board opamps with flying leads. True electrical heart bypass surgery. 😂
I was interested in this 10k:10k one that might be easier to drive.
I was interested in this 10k:10k one that might be easier to drive.
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I used similar ones to those and 10k:10k on Ian Canada's passive IV. He thought they were not far off the SW if his Lundahls. I thought the 3255 might be better with 600ohm input. Maybe I'll try the 10ks. I have some 600:10k but that will give me a load of gain I assume.
For PFFB enabled amps, the native 3255 gain is 15dB. 5x gain is 14dB and the perfect amount to take it to 29dB allowing it to be used like any normal power amp.
I was going to use these as buffers out of my Denafrips dac as they said I could not drive a preamp and headphone amp with a splitter. Should I use 2 or would it be better with 4? What do you recommend as power supply on these? Do the need a excetually clean power supply?
They can drive 600ohm loads so, so if your combined preamp and headphone amp input impedances are greater than 600ohms you should be good. Most devices have input impedances on the 10kohm range. You definitely want at least a regulated PSU like your usual LM7818 and LM7918 for example. But nothing crazy low noise is needed. Another option is to use a tiny PCB mounted dual rail DCDC switching supply with 12v input (output: 80mA +/-15v) and follow it up with an CLC filter. You can get these from Murata, Meanwell, Traco, etc. These are MHz frequency switching and something like a 100uH ferrite core and 4.7uF X7R’s will clean them up nicely. Sort of like what I use on my BTSB boards for the built in PSU.
Here is a schematic of the filter used on the BTSB:
Murata MGJ2D121505SC DCDC
Here is a schematic of the filter used on the BTSB:
Murata MGJ2D121505SC DCDC
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