UCD180 questions

[paradigm]

Hi!

I'm at the final stages of building a UcD400 and a second UcD180 amp.

The first one does produce some hum, when hooked to a grounded outlet. (pin-1 bridged to chassi lug)

I know hum problems have been discussed earlier, but I can't remember, whether the pin-1 on the Neutrik chassis connector, should be bridged to the small ground lug, or not.
I don't seem to be able to find it either, so I hope you don't mind me asking about this again.

The shield on the wire, I have only bridged between pin-1 and housing lug, on the primary side, i.e. connecting the shield to the chassis of the preamp.

At least, this is how I remember it from the earlier discussions. I hope this is correct.

Grateful for any help on this.

BR
Roland

[Bruno Putzeys]

Originally posted by paradigm
Hi!

I'm at the final stages of building a UcD400 and a second UcD180 amp.

The first one does produce some hum, when hooked to a grounded outlet. (pin-1 bridged to chassi lug)

I know hum problems have been discussed earlier, but I can't remember, whether the pin-1 on the Neutrik chassis connector, should be bridged to the small ground lug, or not.
I don't seem to be able to find it either, so I hope you don't mind me asking about this again.

The shield on the wire, I have only bridged between pin-1 and housing lug, on the primary side, i.e. connecting the shield to the chassis of the preamp.

At least, this is how I remember it from the earlier discussions. I hope this is correct.

Where pin 1 goes (normally chassis, straight at the plug using the lug) is not so awfully important. More important is to make sure the connection to the source is made correctly. If you have an unbalanced source, pin 1 goes (via the cable shield) to the source's ground. Pin 3 is also tied to the source's ground through one of the two wires in the cable. Pin 2 goes to the signal through the other wire.

If the problem persists, could you give further details about the whole set-up?

[stef1777]

To help.

[paradigm]

Hi Bruno!

At the moment it's a mixed setup with some components unbalanced ( the pre-amp section of the H/K AVR5000).
From the CD-player I use optical SPDIF to to the balanced Behringer UltraCurve. From thera the signal is balanced, but converted to unbalanced as it enters the H/K and from there, the signal out is once again unbalanced, then the signal goes to the balanced Behringer UltraDrive (digital active X-over). The signal then goes balanced to the UcD180 and soon to some more UcD amps (Quadra-amping).

I know it's sub-optimal to swtch like this, but until I can find a reasonable priced, balanced multi-channel attenuator/preamp, I'm forced to try to do the best with what I've got.

BR
Roland

[paradigm]

Hi stef1777

Thanks for the pic. That's how I've done it, when going from UB to B.

BR
Roland

[Bruno Putzeys]

Can you check if the problem persists when the UD is connected to the amp but nothing else is? It could be that the ground loop problem is located elsewhere in the chain but that it only materialises when the amplifier is grounded.

[stef1777]

If you have a TV cable connected to the audio installation (thrue TV or DVD), disconnect the cable from the operator to check.

[ghemink]

Originally posted by paradigm
Hi Bruno!

At the moment it's a mixed setup with some components unbalanced ( the pre-amp section of the H/K AVR5000).
From the CD-player I use optical SPDIF to to the balanced Behringer UltraCurve. From thera the signal is balanced, but converted to unbalanced as it enters the H/K and from there, the signal out is once again unbalanced, then the signal goes to the balanced Behringer UltraDrive (digital active X-over). The signal then goes balanced to the UcD180 and soon to some more UcD amps (Quadra-amping).

I know it's sub-optimal to swtch like this, but until I can find a reasonable priced, balanced multi-channel attenuator/preamp, I'm forced to try to do the best with what I've got.

BR
Roland

Hi Roland,

Your solution is to replace everything between the CD player and the UcD with an DEQX PDC unit (www.deqx.com). I own one and I use it for my active 3-way speakers and I have it with the analog XLR output option. Sound is great in combination with the UcD modules. The DEQX has digital crossover that are phase-linear, it also corrects your drivers and if you want you can use EQ as well (personally I never use EQ). And sometime in the future you will have room correction as well, at least, that is what DQX promises :-)

Best regards

Gertjan

[UrSv]

Originally posted by ghemink



Hi Roland,

Your solution is to replace everything between the CD player and the UcD with an DEQX PDC unit (www.deqx.com). I own one and I use it for my active 3-way speakers and I have it with the analog XLR output option. Sound is great in combination with the UcD modules. The DEQX has digital crossover that are phase-linear, it also corrects your drivers and if you want you can use EQ as well (personally I never use EQ). And sometime in the future you will have room correction as well, at least, that is what DQX promises :-)

Best regards

Gertjan

I suspect his problem will be that the DEQX supports too few channels and costs almost 5 times what the DCX/DEQ setup does. The same problem I have actually otherwise I would already have one...

[paradigm]

In a day or two I will have to do some serious re-wiring at the back of my (heavy) rack anyway, when the UcD modules arrive and I think I will wait for that, to check out your suggestions, to see if they can make any difference.

But regardless, I would appreciate if you could tell me if I schould bridge the (balanced) pin-1 to the chassi-lug, or not on the amp. What would you prefer?

I would like to have the amps as ready as possible when the modules arrive, in order to be able to hook them up as soon as humanly possible, if you know what I mean.

BR
Roland