Connecting Speakers Question

[DiazRomero]

My amp (SVT-3Pro) has two 1/4" speaker output jacks. Ocassionally, depending on the gig, I will use two 8 ohm cabinets. My question is should I run a cable from each jack on the amp to each cabinet or should I daisy chain the cabinets to each other? One cabinet is a 4X10 the other is a 2X10.

 

[DeluxeRed]

It makes no practical difference as they are both wired in parallel on both the amp and the cab. I always prefer shorter leads, fwiw. With my 3P, I use the speakon, which requires daisy chaining, as there is only one port on the amp but two on the cabs.

 

[imkelvis]

If you daisy chain those cabs you're running them in series. That's a 16 ohm load. I don't know how your Ampeg would feel about that. I had that same (Great!) head for years and always ran 2 8 ohm cabs, one off each output for a total 4 ohm load. Worked great and got the most power out of the head. It' also a good idea if your speaker cables are the same length. I don't know how much difference it makes if you have a 3' and 4' cable but you don't want a 3' and a 20'. You get into a phase (cancelling?) issue at some point.

 

[Slevage]

Unless the 1/4" jack are specifically wired to be in series (which would be unusual), your speaker cabinets will be in parallel. Same connection at amp output or cabinet.

john

 

[DeluxeRed]

If you daisy chain those cabs you're running them in series...

That is NOT correct. Daisy-chaining Ampeg (and 99% of other cabs) puts them in parallel, reducing the total Ohms.

From the Ampeg product manuals (for the 8ohm cabs):

"The Speakon and 1/4" jacks are wired in parallel, allowing for easy daisy chaining from one speaker to another. Each of the jacks can be used as an input or a through connection."

 

[imkelvis]

Well, you can't argue with the manual. color me corrected.

 

[billfitzmaurice]

If you daisy chain those cabs you're running them in series. That's a 16 ohm load.

-1. The jacks are parallel wired, not series.

I don't know how much difference it makes if you have a 3' and 4' cable but you don't want a 3' and a 20'. You get into a phase (cancelling?) issue at some point.

Electricity travels at about .7 x speed of light. Phase differential between even a 1 foot and 1,000 foot cable would be in the mega Hz range at least. But for current and voltage drop issues using longer cables than necessary isn't the best idea.

It makes no practical difference as they are both wired in parallel on both the amp and the cab.

There is a difference. With the cabs separately connected both cables carry only the current load to their respective cabs. With daisy chaining the current to both cabs passes through the one cable connected to the amp. Most of the time it's not a concern, but with very high power into low impedance loads and smaller gauge cables it could be.

 

[David Jayne]

Yes, it's very, very unusual to see series connections on speaker cabs.

 

[DiazRomero]

Thanks for the info, Guys. I kind of suspected that. I just needed the confirmation you provided.

 

[wildhorse]

Some mfg like Acoustic advertise that they have 2 jacks so that you get full output power. It's just a marketing scam imho and really there is no practical reason to do it one way or the other. Go with which ever way gives you the shortest cables as previously suggested.