Phase switcher doobie firkin

[Kiwi]

Dave

I've got two outputs on my Trace V8, one is a jack, the other is an XLR. I've got an issue where the output of two speakers is considerably lower than when one is plugged in and its been suggested that there might be a phasing issue.

I'm wondering if the XLR cable is wired so that the cabs are out of phase. Do you know of any quick (ie. solder free) ways to change the phase relationship between speakers being fed by the amp?

[Stewart]

Easiest would be to make up a cross-wired jack plug and socket (to reverse the phase of the jack output)

[DHA]

[quote name='Crazykiwi' post='87854' date='Nov 13 2007, 01:55 PM']Dave

I've got two outputs on my Trace V8, one is a jack, the other is an XLR. I've got an issue where the output of two speakers is considerably lower than when one is plugged in and its been suggested that there might be a phasing issue.

I'm wondering if the XLR cable is wired so that the cabs are out of phase. Do you know of any quick (ie. solder free) ways to change the phase relationship between speakers being fed by the amp?[/quote]

A quick way to check if it's a phase issue is to point the speakers at each other and move them towards each other, if they are out of phase they will lose volume as they get nearer. Not easy to do if the speakers are in the same cab I grant you! If this is the case then you need to check how the speakers are wired visually or with a meter. There should be a + and - tag on each speaker.

The XLR cable should be wired 1 to 1 so I don't think it would be that. But first we need to find out if it's a phase problem.

Dave

[DHA]

[quote name='Stewart' post='87872' date='Nov 13 2007, 02:23 PM']Easiest would be to make up a cross-wired jack plug and socket (to reverse the phase of the jack output)[/quote]

It's not a bad idea but you need to be careful as by doing this the outside (metal part) of one of jacks will be positive with respect to earth. At 400W this is 120Vac into 4 ohm so this will mean touching the jack will make your eyes water for a while.

Dave

[Mr. Foxen]

I read, but don't do it till someone confirms they will take blame, that you can check speakers are in phase by touching a 9v battery across the jack , and if they don't all stick out or all suck in its wrong.

[Kiwi]

[quote name='DHA' post='87874' date='Nov 13 2007, 02:25 PM']A quick way to check if it's a phase issue is to point the speakers at each other and move them towards each other, if they are out of phase they will lose volume as they get nearer. Not easy to do if the speakers are in the same cab I grant you! If this is the case then you need to check how the speakers are wired visually or with a meter. There should be a + and - tag on each speaker.

The XLR cable should be wired 1 to 1 so I don't think it would be that. But first we need to find out if it's a phase problem.

Dave[/quote]

OK, looks like I'll have to give it a blast next rehearsal, the issue only happens at performance volumes and my neighbours probably wouldn't appreciate 400w of tube amp rattling their cutlery.