Can I connect balanced output straight to Quad 405?

[Mr.Ian]

I have a range of custom built leads but to be honest the cheap xkr to rca adapter plugs from ebay have always worked well for me apart from the space needed to fit them

[Ali Tait]

Yes agreed Ian, have used those also, never had a problem.

[Barry]

I cant really see what difference the plugs and sockets make, it is the cct configuration which matters.

Agreed, Figures 3 and 4 are equivalent and show the correct way to do it.

Depending on whether the balanced output of the source has a series resistors fitted, you may be able to use the cables available on eBay, Amazon etc., but if series resistors are not fitted, then connecting pin 1 and 3 together will short one half of the output, with possible damage.

[HarryCrumb]

Thank you to all of you for this advice, it is such a massive help. I've got tonight and tomorrow free to ingest it all. It's not an ideal setup but it's serving a purpose.

...one day audio will make sense to me, perhaps.

[Ali Tait]

Agreed, Figures 3 and 4 are equivalent and show the correct way to do it.

Depending on whether the balanced output of the source has a series resistors fitted, you may be able to use the cables available on eBay, Amazon etc., but if series resistors are not fitted, then connecting pin 1 and 3 together will short one half of the output, with possible damage.

How would that damage anything?

[Barry]

How would that damage anything?

Because if a series resistor is not fitted, there will be a direct short across one half of the output. That could well damage the output driver.

But several, if not most, sources having a balanced output are fitted with such resistors so the cables from Amazon et al. are sufficient (I have used similar cables between the balanced output of my Levinson preamp and a Quad 405-2). However there are some units which do not have output protection, so to be on the safe side I would recommend connection as shown in Figure 4 of the above cited reference.

Without looking at the circuit diagram of the OP's Behringer amplifier, I can't say if that is necessary.

[Pharos]

I am not familiar with your feeding device, but;

In general signal sources IME are not in danger when shorting their O/P because there is sufficient O/P impedance to prevent damage, but this is certainly not the case when power is involved.

Examples IME, O/P of a preamp, O/P of a tape recorder, O/P from a preamp to a tape recorder.

[Barry]

The user manual of my dual-mono balanced output preamplifier, says that if one wishes to connect it to a power amplifier having an un-balanced input, then pins 1 and 3 of the XLR connector can be connected together. This is because the output impedance of the preamp is finite at 10 Ohm. I have used such a preamp with a Quad 405, using the above arrangement, without incident.

But I have other balanced output devices which use a transformer on the output, and I would not like to short out one half of the secondary winding. In fact the instructions state that the minimum load is 600 Ohm.

[HarryCrumb]

Without looking at the circuit diagram of the OP's Behringer amplifier, I can't say if that is necessary.

I’m struggling to find a cable diagram of the unit. Best I can find is a quick-start guide with the specs in. There is a sister unit which is similar but with a different layout and the outputs are labelled as balanced/un-balanced. The unit I’m working with though is balanced only.

I’ve been reading though all the links that have been posted. I struggle with the finer detail but essentially I can see what I need for the job. If I make myself a cable with no connection/cold to pin 3, having hot on pin 2 and shield on pin 1, I should be ok. I have some nice Van Damme RCA to XLR cables at a good length but they are too nice to butcher and the XLR is male. I wondered about making up some short sex-change cables wired as per diagram 4b so I could utilise the Van Damme cable, but I think it might be better to just make the cables up in one piece. Out of interest, would that idea work? The van dammes are wired - pin 2 - hot to tip; pin1 + 3 shorted to sleeve.


Now, that Rane document that I have been referencing does advise sticking to 3m max length unbalanced cables. I won’t be running these across a busy stage floor so do you think I could get away with 5m? Possibly 4 at a stretch…? They’ll be a good few feet away from any mains cables.

[Barry]

I’m struggling to find a cable diagram of the unit. Best I can find is a quick-start guide with the specs in. There is a sister unit which is similar but with a different layout and the outputs are labelled as balanced/un-balanced. The unit I’m working with though is balanced only.

I’ve been reading though all the links that have been posted. I struggle with the finer detail but essentially I can see what I need for the job. 1 If I make myself a cable with no connection/cold to pin 3, having hot on pin 2 and shield on pin 1, I should be ok. I have some nice Van Damme RCA to XLR cables at a good length but they are too nice to butcher and the XLR is male. I wondered about making up some short sex-change cables wired as per diagram 4b so I could utilise the Van Damme cable, but I think it might be better to just make the cables up in one piece. Out of interest, would that idea work? 2 The van dammes are wired - pin 2 - hot to tip; pin1 + 3 shorted to sleeve.


Now, that Rane document that I have been referencing does advise sticking to 3m max length unbalanced cables. 3 I won’t be running these across a busy stage floor so do you think I could get away with 5m? Possibly 4 at a stretch…? They’ll be a good few feet away from any mains cables.

1 Yes, that should be fine. As shown in Figure 4.

2 I would break the connection between pin 1 and pin 3, so the return/shielding is connected to pin 1 only. Again as Figure 4.

3 You can probably get away with a 4 - 5 metre length, provided the cable has good shielding (i.e. has a good optical coverage). A braided shield is best, or if lapped, has a supplementary foil layer.