Ableton Forum

I have a Saffire Pro 40 and 4 pieces of equipment which use unbalanced outputs.

If I use a balanced TRS cable from the pro 40 to whichever equipment (effectively connecting the ground of the mixer to the ground & -ve of the unit) I get no noise. With an unbalanced cable (which effectively connects the -ve and ground of the mixer to the combined ground and -ve of the unit) I get noise.

Should I be using a balanced/unbalanced adapter to isolate or "lift" the ground and connect the two negatives?

I have see balanced and unbalanced adapters but 8 of them would be massively expensive!

An alternative would be to use an ADAT I/O which has unbalanced inputs however I cant find one.

ADAT is a digital format, so noise on a cable isn't a concern (at least this much noise.)

try everything you can.
- make sure all your gear is on the same circuit. (same circuit breaker.)

- try making your own cable. refer to wikipedia to see what get connected where. currently you're using a system that ties both the negative signal and the ground of the balanced cable to the ground on the unbalanced cable. it might work to only connect the ground, leave the minus signal floating.

- buy ONE of those converters and see if it helps.

- find the source of the noise and kill it.


until then you can use a GATE plug in in Live to cut out the noise from your gear. just set the threshhold to just above the level of the noise.



hth.

Sorry I wasn't clear. Its the analogue inputs that are creating the noise.

Regarding the IO I just wondered if there is an IO that has unbalanced inputs rather than balanced which seems to be the standard.

Unbalanced/balanced adapters include transformers I believe which is what makes them expensive hence the interest in an unbalanced audio interface which could utilise the ADAT or optical input on my Pro 40.

The main question remains:

joewalch wrote:
Should I be using a balanced/unbalanced adapter to isolate or "lift" the ground and connect the two negatives?

joewalch wrote:
Should I be using a balanced/unbalanced adapter to isolate or "lift" the ground and connect the two negatives?

I just connect V+ to V+, V- to gnd and gnd to gnd. you can use a transformer, but it's not required, that's just one way to do it.

this looks to be a good paper on the electronics of balanced vs unbalanced.
http://www.jensen-transformers.com/an/an003.pdf



hth, pretty busy at work, can't dig much further.

I'd try this before spending out money on any adapter box:

XLR to 1/4" mono jack via twin screened cable.

XLR is wired in normal balanced fashion.

1/4" jack is wired so that the cold (-) wire goes to the jack's barrel/sleeve connection. The hot (+) goes to the tip of the jack. The cable screen (which is the XLR's ground) mesh or bundle of wires should be cut back and insulated to prevent it from touching the barrel of the jack plug or anything else.

This quite often does the trick.

Synthbuilder wrote:I'd try this before spending out money on any adapter box:

XLR to 1/4" mono jack via twin screened cable.

XLR is wired in normal balanced fashion.

1/4" jack is wired so that the cold (-) wire goes to the jack's barrel/sleeve connection. The hot (+) goes to the tip of the jack. The cable screen (which is the XLR's ground) mesh or bundle of wires should be cut back and insulated to prevent it from touching the barrel of the jack plug or anything else.

This quite often does the trick.

I had the same thought, I think its called "lifting" the ground. I think I will make up some adapter cables for this. Will let you know how I get on.

The biggest culprit is a Juno 106. I had considered changing the existing output to balanced but I'm not sure if this is possible.