UCD180 questions

[trango]

First of all, I would like to thank the guys at Hypex for providing such an outstanding amplifier. I'm using four channels of UcD180AD and two channels of 400AD and I'm extremely satisfied with their performance.

I have a question, I've tried to search the forum and the hypex datasheet without any luck and I hope I haven’t missed the answer somewhere...

I’m planning to drive the bases of my Linkwitz Orion with four channels of UcD180AD and use power JFET based amps for the mid and highs (PASS Zen version 9). The idea is to build 2 chassis that each holds 2 channels of Zen and 2 channels of UcD180AD. The problem is that the Zen will be very hot and I expect the case to hold a temperature of 60-65 degrees centigrade. Will such high temp damage the Hypexs or decrease their performance?

Any comments?

[axelarnold]

Hi,

just ordered the components for my UcD 180 dual mono setup and planning to start with passive preamp (High quality 10k log stereo Pot) and unbalanced RCA Source.

According the hypex application note http://www.hypex.nl/docs/wiring.pdf signal ground (Pin 2) is connected to pin 3 (signal negative) via chassis shield. Does this results in half gain?

Axel

[Kevin Haskins]

I'd recommend building the interface cable and wire the input of your amp with an XLR. The convention for balanced XLR wiring is:

Pin #1: Shield/Chassis

Pin #2: Positive input

Pin #3: Negative inverting input

This way when you have ground currents flowing between equipment it is carried on the shield of the cable rather than the analog ground reference.

I sell a cable kit that is a very affordable way of implimenting this.

http://www.diycable.com/main/product...roducts_id=609

Download the PDF directions and it gives very clear directions on how to make the interface cable.

[axelarnold]

Thanks, but i cannot see, how the cable concerns unbalanced input / pot / power questions.

At first i have unbalanced input and stereo pot, even with XLR at the amp.

Even if connecting shield and cold wire at the source - they are connected.

Does this results in half power or gain (only 1/2 of the balanced amp is used)?

Axel

[maxlorenz]

No.

[axelarnold]

Thanks Maxlorenz, realy happy about this (because of my costy Pot).

There was an former post, regarding the modify of buffer-gain (by changing one or two resistors Rg, Rf) when Attenuator is used. Out of your reply i think this doesn't mak sense?

Axel

[Kevin Haskins]

Sorry... I got in a hurry on my reply and hadn't read your questions carefully.

I'm partnering with John Chapman of Bent Audio and we are making an integrated version of our kit that will use a relay based stepped attenuator in passive mode. It has the advantage of offering a remote but anytime you use a normal stereo pot you have to convert over to single ended before the pot.

Wire the RCA input as per the Hypex documentation (blue, black wire + adaptor cable shield) into the ground connection on the pot. Use the red wire on the signal. Bruno recommends lifting the chassis safety ground and using double insulation techniques. I'm not keen on lifting safety grounds so I typically recommend that rather than using a stereo pot, buy a four ganged pot and you can then wire it for a true balanced input and use the adaptor cable as I suggested earlier.

In terms of gain don't worry about changing the gain (via resistor changes) unless you need it. If you find you need more it is easy to change a couple resistors on board to get extra gain.

[koldby]

Axelarnold, Kevin Haskins.

You do NOT have to convert to single ended just to use a stereo pot as volumen control. If you place a resistor in series with both the + and - input and use the pot to short circuit betwen the + an - at the UcD input.

This way you have a very good balanced volumen control.

For most applications you will have to increase the gain in the UcD modules to use a passive volumen control instead of a pre-amp. But it is very easy to do so.



Koldby

[Kevin Haskins]

Hmmm.... I can understand using a pot to control the ground to signal resistor. Do you have a link or something that explains what your talking about in more detail?

[Peter Daniel]

http://www.diyaudio.com/forums/attac...amp=1031349309