Stereo outs to a Mono in

[didle]

Hi All,
In my GNR tribute, some kind of chorus is pretty much mandatory. I found myself a Yamaha SPX90 in excellent condition a few months ago (as used by Duff McKagan in the original band). The problem I have is that the Yamaha has a pair of stereo outputs. It's two chorus settings don't have any option to pan both sides to one output meaning that unless I run two amps I can only get 1 side of the effect. This means that every few seconds part of my sound disappears.

I could quite easily knock up (or buy) a cable that would take both outputs from the Yamaha and feed them into the single input from my amp. Are there are issues with doing that other than an increase in volume?

Cheers,
Doug

[thepurpleblob]

I don't know anything about the SPX90 and you don't say what the outputs actually are. Personally, I would invest the 30-odd quid in a basic two channel mixer. What you don't want to do is to use a stereo-to-mono cable because they will just short the outputs together. That *might* work but equally well might break it or sound crap.

Failing that, it could be done with a few resistors or a pot but you really need to know the impedance of stuff - hence the mixer.

[BigRedX]

Are you sure that the SPX90 doesn't revert to mono if you only connect one channel (normally the left)? Most stereo effects do this.

[musophilr]

I think the SPX90 allows you to use the one o/p as mono so long as you don't put a plug in the other o/p. At least that's how mine is wired, and I don't notice any ill effects ('scuse pun).

[didle]

I would have expected it to revert to Mono if only 1 output is connected but I'm pretty confident it's not in this case. I can definately hear the sound level drop and then return - it's quite noticeable.

I'll try the other output later on - I'm not sure if I've tried that before.

The mixer idea sounds like a good one and isn't something I'd thought about before. I'll look into that once I've exhausted the other options.

Thanks!

[obbm]

[quote name='thepurpleblob' timestamp='1333531408' post='1602849']
What you don't want to do is to use a stereo-to-mono cable because they will just short the outputs together.
[/quote]

A proper stereo to mono cable should have mixing resistors. 22K is a good value, one in series with each of the stereo ouputs.

[BigRedX]

Looks as though the SPX90 is [url="http://uhaweb.hartford.edu/CETAAUDIO/manuals/spx90.pdf"]stereo only[/url]

If you go the mixer route you might need to find one with phase switches on the channels or make up some reverse phase leads as some of the effects could disappear when summed into mono.

[RandomProddy]

You meed something called a "line combiner", [url="http://www.thomann.de/gb/millenium_sml_21.htm"]http://www.thomann.d...nium_sml_21.htm[/url] but for TRS/TS connections.

Edited April 4, 2012 by RandomProddy

[paul_5]

two bass amps? Win!

[zero9]

I'm looking to do a similar thing to combine the output of a stereo instrument output to a single mono, but am considering using an A-B box to combine the stereo signal. Some will have individual volume controls as well, such as:

[url="http://www.gear4music.com/Guitar-and-Bass/Belcat-ABS-520-Dual-Input-A-B-Box-True-Bypass/FY4"]http://www.gear4music.com/Guitar-and-Bass/Belcat-ABS-520-Dual-Input-A-B-Box-True-Bypass/FY4[/url]

[thepurpleblob]

[quote name='obbm' timestamp='1333535472' post='1602961']
A proper stereo to mono cable should have mixing resistors. 22K is a good value, one in series with each of the stereo ouputs.
[/quote]

Sorry I meant "mono to stereo cable", which seem more common. I think you might have to make your own to be safe. I've never managed to find one advertised that admits to having the resistors.

Edited April 4, 2012 by thepurpleblob