ICs 9, 10, 11 and 12 form the IVYII stages. They are OPA1632. They can supply 150mA/channel.

Using an offboard with resistors would work fine. You could bypass the S/PDIF comparator circuit as you will have TTL voltage, then you can leave the on board terminators alone, as you won't be going through them.

Edited by user Wednesday, April 8, 2009 8:22:00 PM(UTC)  | Reason: Not specified

Opps, I now see the dumbness of my IC# question! I read what you said Brian, but didn't tie it to your PCB pic because I thought the chips with the dimples and thermal pads underneath were the OPA1632's. Can you comment on the function of the 4 unlabeled chips directly in line with both sides of the DAC?

Thanks again,
Tom

Edited by user Friday, April 10, 2009 7:00:43 PM(UTC)  | Reason: Not specified

One of the lateral ICs is a dual integrator which sets the common mode voltage for each of the op1632s on each side. The other is an extremely low noise low output impedance voltage regulator. :)

Cheers!
Russ

Hi Guys,

I've been studying the differences between AES3 (AES/EBU) and SPDIF and have a couple of questions please. It appears to be more than just a level and balance/unbalanced difference. While the audio data is the same, the channel status bits are completely different between the two. My primary question is what the ESS9018 will do when presented with AES formatted data (professional vs consummer), corrected for level differences. Does it ignore those channel status bits, or recognize them a AES format, or just reject the data?

If it's the latter, I have a couple of choices. The Lynx AES card I'm using has a format change option, but I have not confirmed whether it does more than just change the level. A second option is use the AES input to your 4:1 SPDIF Mux/Receiver card (X3 cards).

My second question is whether you believe the SPDIF receiver on the ESS9018 is superior to the Cirrus CS8416 for minimum jitter in clock reconstruction. The ESS White Paper is very persuasive with their approach.

I appreciate your thoughts,

Tom

Edited by user Wednesday, April 22, 2009 1:39:54 PM(UTC)  | Reason: Not specified

Russ,
this leads me to the following questions:

1) Are you saying that it is likely to be better to "bypass" the MUX with SPDIF sources?
2) Is this true also if the MUX and B32S are connected via SPDIF or only when they are connected via I2S?
3) Does the ES9018, like the B24, auto detect TTL level SPDIF even if jumper-configured for "non-SPDIF"?

Considering the decoding versatility and quality of the ES9018 maybe some kind of "mechanical" input selection device (SPDIF, AES, I2S, DSD...), a little more compact than a stack of OTTO's, would be a nice add-on. I love OTTO but a similar sized (or preferably) smaller 3:1 switch, or even 4:1 would be great!

Nic

1) Well all I can say is its definitely no worse. :)
2) If you use the MUX with SPDIF out it is a direct pass through.
3) Yes.


Cheers!
Russ

Hi guys!

I'm working up the parts and circuit to add AES inputs to three new Buffalo 32S cards. Not knowing the relevance of the comparator circuit on the SPDIF input, I think I would like to use it if it has benefit for AES levels. With the possible exception of using the DSD input capability at some future date, the cards would only ever be used for AES inputs. I have no requirement ever for the SPDIF input capability, so alternating component values or circuitry killing future SPDIF usage is completely acceptable.

With that said, is the SPDIF input circuit you are using lifted from the ES Evaluation board, and/or can you recommend a suitable input circuit for a transformer coupled AES source?

Thanks in advance,

Tom

I am planning to hock up the Buffalo 32 to a Lynx Two B sound card. This card can output both SPDIF and AES/EBU. Will there be any benefits using the AES/EBU over the SPDIF?

You don't have to wire the input side of the AES GND if you don't want to. But in practice I have never seen any harm.

Wall that the cct above does is shift the signal level down to consumer level. The protocol is still AES.

The benefit to balanced AES/EBU is that you will get less line interference because of the higher levels and balanced transmission up to the source. Other than that there really is no advantage.

Cheers!
Russ