60 cycle hum

Ludwig

I am using the driverack PA to manage my home speaker system-
tri amped custom

TAD 4003 high freq driver-horn
TAD 12\" mid freq
TAD #2 15'' drivers- low freq/sub

the high and mids are driven by BAT VK200 amps
the low end by Crown macro reference amp

I am getting an annoying 60 cycle hum via the midrange outputs of the Driverack PA, switching speakers and amps has no impact and the high and low outputs seem to be clean. lifting the ground or swithing various power line in options is no help including filtered UPS system.

I don't see any reference to this as an issue in documentation or other posts.

Is this a problem anyone else has encountered?

On another note does anyone know if the BAT amps behave as any of the preset amps and same question with the Crown macroreferance.

many thanks

Dra

To be clear... are you saying that the hum does NOT follow the amp? Have you swapped cables from DRPA to amps? Does the problem move?
Obviously, you are not hearing 60 hz in your mids. It has to be a harmonic.
Try setting up a 3-way, but set each band of the cross-over to be from where-ever the x-o point was for your mid band to out. Connect the low output to one side of a BAT VK200 to a mid speaker and the high output to the other side of the amp to the other mid speaker. If there is no hum then move the cable from high or low to mid and see what happens.

Good luck and report back.
DRA

Gadget

If, however there IS a hum still.. then a ground loop is at fault... I know nothing of these amps.. are they grounded? Some Crown amps use a grounded bridge configuration, does the hum go away with the Crown disconnected from the setup? There are numerous possibilities here since we are blending consumer and pro audio equipment. The rub here is that consumer equipment doesn't always have a ground plane and Pro audio equ. does. This can cause havoc. Each piece needs to be added or subtracted till the problem is identified. Sometimes the cabling needs to be modified to isolate a problematic piece... with Balanced and unbalanced sources we sometimes need to remove the shield in order to remove a ground loop... If you are not familiar with these processes we need a LOT more info in order to provide schematics and further troubleshooting... no detail is too small in these types of problems...

gadget

Fanman20

Are all your pieces of equipment connected to the same power source? (Plug all equipment into the one power point!) Most of the \"hum\" problems that I see are related to equipment plugged into 2 or more power points.

Ludwig

Many thanks for the feedback-
I did a lot of systematic troubleshooting and I find that in fact I was unjustly blaming the DRPA. I was getting the harmonic sound via the mid channel only based on the frequency and crossover- obviously.

The problem turned out to be twofold-
1- one of the BAT Amps had a blown fuse internally (and the channel still functions!!) These are fully balanced signal path amps with no neg feedback circuitry- internally there are 2 circuit board fuses per channel and on 1 of the amps a single fuse had blown and the only obvious sonic problem was the introduction of a noise harmonic.

2- My DISH HD sat receiver introduces noise into the system at a much lower level then the blown fuse but still a problem. The noise is present even with all other inputs disconnected- particularly the sat coax lines. Switching circuit input and commonality with other components makes no difference. I will try the optical out signal as soon as I pick up my Rotel preamp today from its service
I'll be speaking with the DISH people about this.


again I really appreciate the feedback and I am pleased that the problem turns out not to be the DRPA

Thanks
Ludwig