It would be worth checking the output on a scope to be sure you are not getting oscillation. There is a lot of parasitic capacitance and inductance added there, not to mention antenna for picking up RFI/EMI.

I'm not saying it's not good and not possible, just use an abundance of caution.

I've just bought some Sennheiser HD 600 headphones and want to drive them from the Ivy III in a balanced setup. Most people seem to use 2 3-pin XLRs or 1 4-pin, with shield ground not used.

Would it be worth using 2 cables - 1 for each driver and each with the shield connected at the Ivy III end? I actually already used 2 lengths of Mogami 2893 to re-cable my Grados (both cables going into a 1/4" jack). Most seem to use 24AWG starquad and split it - using 2 cables makes the split unnecessary.

Either way I assume I connect the chassis XLR socket to the balanced outputs of the Ivy III? As a noob, I'm a little confused as to how connecting just the - and + of the balanced output is different to the signal and ground of the SE output. Also, why are XLRs always used? Could one not use 2 RCAs?

Thanks Russ but I'd like to keep the original cable for when I need to use them with a TRS plug (or if I sell them). I quite enjoy making cables anyway, plus I've already bought a pair of the Cardas plugs for the headphone end.

You can really use any connector you want. The main reason for not using something like RCAs is to prevent connection errors later... if you connect a regular SE-input stage to you balanced outputs, it would typically connect the grounds, which in this case would actually be the balanced signal's - out, and that would be bad. A unique connector means no mistakes.



SE outputs (typical RCA connectors for example) use one wire for signal and one wire for ground. Balanced signals (XLR connectors) use one wire for ground and two wires for signal, + and -. the two signal wires are identical, but 180-degrees out of phase. Picture a sine-wave, and call that the + signal. The - signal would look identical, but when the + goes up, the - goes down. Here's some additional reading: http://en.wikipedia.org/wiki/Balanced_audio

I'll preface this by saying that in many cases I don't think that going balanced provides huge benefits, but......



Sure, but speaker wire is a pair of wires to each speaker. You don't run the ground from a single connection on the amp, to one speaker, then to the other speaker. But this is essentially what you are doing in unbalanced headphones.



This could be important with respect to the Buffalo.

Running balanced, each individual driver is powered by a single OPAMP. Plenty of power, and no unnecessary steps.

Running unbalanced, both drivers are powered by the same OPAMP. Less power, and the signal goes through this extra OPAMP.

It all makes perfect sense to me now.

When I considered building the Buffalo II/Ivy III it was mainly to use as a DAC/pre-amp. It's just a great added bonus that it's a fully balanced headphone DAC/amp as well.

When I consider everything it can do, it just seems like better and better value for money.

Just to confirm my understanding (before I start ordering parts), if I add a volumite controller, I can then have a second set of wires coming from the single-ended IVY III terminals going to a headphone jack. If I do this, can I run separate headphones out of the IVY and my headphone amp at the same time?

Also, can I power the Volumite from the same Placid that is powering the BII and Toslink module?

Thanks

So what is the consensus on the output resistance (i.e. jumper or not) for a part-time amp-connected output and part-time headphone-connected output?

I am looking to have 3 output connectors: SE via RCA and TRS in parallel and Bal via 2 XLRs.

95% of the time the connection would be XLR to amp. Occasionally, i would unplug the amp, and connect my bal-cabled HD600s. The SE would be rarely used.

Seems like it would be best to leave the jumpers out?

You could add the resistors, then wire two sets of outputs: one for headphones (to the resistor pads) and one for a pre (to the output termials), then leave them both live all the time.