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I've just measured the SE output of the IVY, one channel is 28.1k and the other is 14.6k  could someone please measure their output to see what theirs is? I thought the SE outputs would measure almost the same I mainly used Balanced out into UCD's but wanted to try the Buffalo and IVY with another amp which is SE only
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Hi Russ,
Just measuring the impedance from the SE to ground on both left and right outputs, I had some slight noise on the right output and through the amp with SE inputs the left channel seemed a little louder, wanting to check everything to be sure
All connections are correct
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There is no direct path through resistors to GND from SE Output. It would have to travel through the opamp, which is probably why you see the very high and inconsistent value. Double check that you have the correct values of resistors in their respective spots. If you still have noise I would start to look at your wire routing, both into and out of the IVY, both PS and Signal. :EDIT: in fact the only reference to GND is at the non-inverting input, and that would have to pass in reverse direction through the op amp to the input stage... Cheers! Russ Edited by user Tuesday, November 18, 2008 10:09:40 AM(UTC)
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Thanks Russ, that explains the possible difference in measurement:-) I have disconnected all wiring from the IVY which are short shielded cable.
Balanced out seems fine, I just wondered if the LM4562 may have gone a little noisy, it sometimes happens in batches of op-amps, obviously its not common but I once had a noisy AD826
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Sure, it is possible that somehow the opamp went bad. If you can manage the swap it, that may be worth while. Edited by user Wednesday, November 19, 2008 7:50:25 PM(UTC)
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Russ White wrote:There is no direct path through resistors to GND from SE Output. It would have to travel through the opamp, which is probably why you see the very high and inconsistent value.
Double check that you have the correct values of resistors in their respective spots.
I have the strange situation that on both left and right channel there is no (0,00 Ohm) resistance between SE and GND (measured with the IVY fully isolated from the other boards). The IVY has been setup for "Buffalo 1" with the notice that I received jumpers for R5-R8 and also for R17-R20 which latter I did not find in the specs. I mounted them anyway. Of course I checked for shortcuts. The board is version 2.01 Tried to play with it anyway  , but the hum is louder than the music hehe. What can be wrong here ? Thanks, Peter PS : Balanced measures normal to me; any change to misuse that for RCA (since I have the hunch we are not going to solve it) ?
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Is this measurement with the IVY off? When not powered, the SE outputs are shunted to Ground with the relay.
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If its happening when the IVY is powered than either the rails are too low, or there is something else wrong...
Brian hit it. Is it powered?
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Quote:When not powered, the SE outputs are shunted to Ground with the relay. I was kind of hoping for that, which is why I tried (playing) anyway. Hearing all that hum made me forget to check again.  Quote:If its happening when the IVY is powered than either the rails are too low I calibrated the +/- 15V without load. Was that wrong perhaps ? Either way, supposed it keeps shunted with power, can I crank up the V, and to which amount then (measured with load !!)? Sorry to be ahead of steps a bit, but I'm not at home right now and kind of eager to proceed when I'm back ! Thank you guys, Peter
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Oh, by now I saw that you guys enjoy a vacation. And indeed, "geek" enough to answer a question here and there.
Well, this is just a small update, and no requirement to respond !
Powered one channel measures 23 Ohm (SE-GND), and the other 12 Ohm. Hmm ...
Btw with load, there's still a neat +/- 15V, so no problems there.
I setup a balanced connection, and no difference (a real loud hum).
I guess I need some proper ground somewhere, which I will find ...
Thanks,
Peter
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