Hi Guys,

a few questions around the Ballsie and it's application with a Buffalo32S.

1. I ordered a balanced Placid with the intention to make that the balanced Power supply for the Buffalo and use the existing LCBPS for the Ballsie Lite. Does that sound reasonable?

2. Would you connect the grounds on the Placid and the LCBPS if you go this way?

3. Can I take the balanced signal on the output of a balanced Joshua Tree and feed it into the Ballsie to have the volume control apply to both? Will that degrade the sound of the balanced output?

4. Can I drive headhpones with the output of the Ballsie lite? What is the voltage swing and what impedance headphones would work well.

Cheers

Thomas

Edited by user Friday, October 30, 2009 8:57:15 AM(UTC)  | Reason: Not specified

#1: I intend to do the same when I receive my Ballsie. Beefy is correct in his reply also.

In going the extra step of perfection, I'll be using the LCBPS that I have to run the spdif mux and toslink to also drive the Ballsie, and leave the Placids just for the Buffalo.

#2: In grounding you want to take care to avoid ground loops. I have a 14awg ground wire in a star configuration that connects to the power supplies and all the other boards. Since the ground planes on the Buffalo32S are connected on the board, I have a single ground connection to the board. Or another way, you can run a ground wire from the Ballsie GND terminal to the LCBPS and then connect that to your Placid or Buffalo.
#3 Others are better qualified to answer this than me, but here's what I think is true. From the Ballsie schematic, it looks like it has a high enough input impedance to not cause distortion. The op amps are high input impedance devices.
#4 I intend to use Ballsie for this purpose as well. Looking at the LM4562 specs, it says it drives 600 ohm loads easily. The OPA2227PA can also drive 600 ohm load. My plan is to start with the volume very low and then turn it up and until my ears melt, then back off a little from there. If your headphones are very sensitive to the volume, you can increase R9 & 10--assuming you are only driving headphones from the ballsie.

RossG

On my system, each board has only one ground connection to a common single ground wire. This helps to prevent ground loops. On simple systems with little more than a couple power supplies and a B32S board, then one may be able to get away with connecting the power supply grounds to each of their respective terminals on the B32S board. On the other hand, I have 2 TOSLINK modules, a S/PDIF mux, the B32S, the Ballsie, and 4 power supplies (and maybe a future audio controller and OTTO switch). With all these devices I had to be wise in making the ground connections to prevent ground loops. Previously, on my B24 in order to get it running as quickly as possible, I had a number of ground connections to the Buffalo board. A high frequency oscillation developed, and was heard through my speakers during certain sections of music with lots of high frequencies (ex. violins). Proper grounding solved the problem.

Ross

If you use the S/PDIF output of the MUX, it is transformer isolated, so grounding becomes irrelevant between the two devices. If you use I2S, you can link the grounds of the two supplies (Buffalo VD and Mux), or even share the same supply, then leave the I2S ground link out (it is there to be sure the TTL voltages are of the same potential).

Grounding of the analog stages can use a similar approach. In fact, I would probably share to power supply between the Buffalo VA and the Ballsie. If you have a dual mono setup for the Buffalo, you can add a third supply for the Ballsie and link the ground as close to the supplies as possible.

Running all the grounds together to a central ground is not a bad idea if you are using several supplies. Keep in mind that the Buffalo's VA and VD grounds are connected on the ground plane of the board, so using the keep it close to that.

I would leave earth ground out of it, by using a ground breaker between the start ground and mains ground (earth) to keep it "out of the loop" unless there is a fault.