BOSOZ I/O and Switching Recommendations

[vdi_nenna]

Hey Guys,

I'm building the Balanced Zen preamp and need help or suggestions for switching between balanced input and unbalanced inputs; what switch to use.

I'd like to have 2 balanced and 2 unbalanced inputs. Also, I'd like to have both RCA and XLR outputs: one set of each.

Diagrams or example would be helpful. Switch recommendations would help too.

Thanks,

Vince

[vdi_nenna]

Anyone, anyone...Bueller?

[metalman]

I used this input switching arrangement on my BZLS. I have had a very minor hum issue with it, but after much trouble shooting I now believe that it is due to my overheating the switch during soldering a couple of connections.

I used a Grayhill switch from Digikey for both input and ouput switching, part number GH7104-ND.

I'll put together a sketch of my output switching / volume control arrangement for you, which has been working perfectly.

My arrangement is a little convoluted, but it removed any need for using jumpers at the XLR jacks when switching between balanced and SE connections.

Cheers, Terry

[vdi_nenna]

Sounds good Terry! Lookin forward to seeing it.

Vince

[lgreen]

My input switching and vol control is here.

I've used relays for switching and dual blue Alps pots for volume (replacing the standard output-side pots).

[vdi_nenna]

Terry, I just looked at the switching. I have to say that it's very clever!

Simple, yet elegant. I'm going to go with it.

Thanks very much!

Vince

[Fox]

Yo Folks,

Just my two cents about the lay out of Metal Man's grounding solution . The minor hum may be the result of the two channels being too far away from each other. That is, the two thermistors may cause a ground loop somewhere in the system. The signal grounds of both channels should connect before the thermistors. So, it should be best to use 1 thermistor between the signal starground and the chassis ground. I experienced a minor humm in my X-BLS also, which was gone when I reached the solution I just described .

Hope this helps,

Fox

[metalman]

Fox,

Thanks for adding your thoughts. I had the same idea along the path of trouble shooting and combined my grounds into a single star ground, but in my case it didn't make any improvement. Could be something about my specific layout in the chassis, but right now my leading suspect is the switch and my heavy handed soldering. I'll be testing out the theory this weekend, so I'll let everyone know if I'm right or not.

Terry,

[metalman]

And here is my output switching / volume control scheme.

Cheers, Terry

[Zapped]

Metalman, or anybody else who has figured this out:


Is it necessary to have a switched output (XLR vs single ended) ?

If you are going to use only one type or another at a time (for example, a balanced connection to an Aleph amp vs a single ended connection to a ZenV4) do you need a switch? If you don't use this swiitching arrangement, do you need to ground the negative output of the XLR connector, kinda like on the input XLR's if you didn't use a switch there?

Sorry. I've been puzzling over how to have both XLR balanced and Phono unbalanced inputs and outputs on my BOSOZ for some time, and still apparently don't get it. I guess my thinking is just unbalanced.