I just finished my BIIIse with IVY III output stage. I am only using the single ended output for now as my balanced amp in no where near being finished.

After about 8 hours of listening I feel that the resolution and level of detail is excellent perhaps even exceptional compared to anything I've built or modded to date.

However, the DAC seems bright and missing some low end. I tried it with my Dynahi 1.0 and my BH Crack. The crack tames it somewhat but it's still bright. Headphones used were HD650 and Headphile Darth Beyers V2 (Bass heavy). I intend to give it at least 100 hours of burn in but I suspect it will only mellow slightly. Basically I want to see what's involved in warming it up a bit and to see what others have done.

My first area to look at would be the opamp doing the BAL/SE conversion. Who has rolled the opamp? What did you use or settle on, and did you achieve better results without sacrificing detail or resolution. The second area would be to change cap values, and if so which ones? Also if I switched the resistors to an "audiophile" brand is 1% ok?

Page 4 of the manual shows the ones that would or could be changed, but I'd need direction on which ones to change and what values to use.

Edited by user Friday, August 1, 2014 5:01:33 PM(UTC)  | Reason: Not specified

Listening with an amp in between

I don't have a way to measure the signal but I don't think anything is faulty there.

I agree with you partly on burn in and psychological effects. With that being said I have built simple circuits in the past with generic parts and then built the same circuit with high end parts and there was a definite difference to me. That of course does not apply to this circuit but give a general direction as a possible way to go to tune the circuit to my liking.

I don't really need extra bass, it just seems like the sound is a bit brighter than I was expecting. The recording definitely effects it I'll agree. For instance Bob Marley's Legend sounds great, but Iron Maiden's Somewhere In Time is harsh on the higher frequencies where as with the analog stage of my CDP they are both great to my ears.

I think you're right. Are you connecting the headphones directly to the Balanced output? If so what connections go where such as +Left -Left go to Pin x and Pin x of the left balanced output.

This is why I don't want to change too much. Except for the opamp. I'm willing to experiment and would like to see what others have tried. The key spot for the passive components is the filter network as shown on page 4 of the manual. I'd like to see if anyone has adjusted those values or at least swapped an opamp.

Edited by user Friday, August 1, 2014 6:42:22 PM(UTC)  | Reason: Not specified

I changed the FIR to slow (turning 4 off on SW1)

This has made a difference. Definitely a step in the right direction

Did you match them to 0.1% ?

roger that!!!

If IVY has an option to solder DIP8 socket in place of bal>se opamp you could try different opamps as they are always affecting sound in that position. Replacing LM4562 with (almost) identical (in specs, but not sound) LME49860 will likely result in more bass, less forward and less bright sounding, although you'll still get that detailed and sharp high end all "LMs" are known for. There are other opamps of course, but to be sure you stay within technical specification it's the easiest choice so far.
P.s. I tried a few opamps in bal>se stage, including paired OPA827, OPA627 on adapter (similar to browndog) and while sonic results are usualy great - i'm yet to confirm with measurements if they perform correctly in that position, because some results are "too good to be true".
But overall - paired single opamps of such level simly feel faster and detailed while smoother, like switching from FullHD to 4K..
The most "warm" of the paired singles is OPA827, at least in Legato. It's bassy, dark/warm, with very delicate highs, completely un-fatigueing, maybe too much for some.

Edited by user Monday, August 4, 2014 6:01:40 PM(UTC)  | Reason: Not specified