With only two speakers driven at any one time the cab will sound terrible. Not designed to work that way.
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A/B Switching Safe?
- Thread starter CliftonBonney
- Start date
Rick Auricchio
Registered Bass Offender
I would have no idea how to do the rewiring. Plus, it's not that important to me. I appreciate the suggestion though.
I'm now confused by the parallel inputs on my cabinet. What exactly does this mean?
My MarkBass head has two outputs. If I were to get another cabinet, I thought I would send one of the outputs to my 4 x 10 and the other to the new cabinet. Is this not necessary with the parallel outputs? In other words, do I just plug the amp into the 4 x 10 and then use the other input on the cabinet to connect to the new cabinet?
Thanks!
I'm now confused by the parallel inputs on my cabinet. What exactly does this mean?
My MarkBass head has two outputs. If I were to get another cabinet, I thought I would send one of the outputs to my 4 x 10 and the other to the new cabinet. Is this not necessary with the parallel outputs? In other words, do I just plug the amp into the 4 x 10 and then use the other input on the cabinet to connect to the new cabinet?
Thanks!
It means you can do this:
Parallel outs on the head and parallel ins/outs on the cab mean you can hook it up any number of ways. Two outs from the head, a single out from the head, in and out of the cab, or you could even do two outs from the head and run two pairs of cabs in parallel for 4 cabs total as long as you keep it at the correct impedance.
Actually, the XLR connector did used to be used for speaker-level conections occasionally. But that was before everyone moved entirely to speakons right? Totally? Good.
No, XLR has never been used to speaker level connections. There's no point in balancing a signal like that. Before Speakons, everyone just used 1/4 jacks. And of course by no means has everyone moved entirely to speakons. Nearly every cab available now has both speakon and 1/4, and newer amps very often still have 1/4 in addition to speakon as well.
Rick Auricchio
Registered Bass Offender
At one time some live-sound cabinets did indeed use XLR connectors. The early SVT used a four-pin Cannon connector; technically that was also an XLR. (The extra two pins completed a circuit that allowed the head to come out of standby.)
The name XLR applies to all connectors of that style: "Originally the "Cannon X" series, subsequent versions added a Latch ("Cannon XL") and then a Rubber compound surrounding the contacts, which led to the abbreviation XLR." The name XLR has nothing to do with the pin count, however, we usually assume that XLR refers to the common three-pin version.
This is incorrect. XLRs were used a lot in pro sound and studios. The B15 used a 4 pin XLR to connect to the cabinet. Very few pro sound companies used 1/4" phone jacks. They simply were not reliable enough.
Paul
SS amps are OK with open loads (infinity ohms). Tube amps ARE NOT. Tube power amps have an output transformer, and the bias current from the tubes runs through the primary of the transformer. With no secondary load, this is a bad situation. Blown OT or tubes or power supply.
Modern SS amps almost always have short-circuit protection, and don't have output transformers (unless it's some esoteric thing). So the open- and short- circuit issues are not a problem. I wouldn't recommend short-circuiting it for fun.
A passive A/B switch with no load is a bad idea. I'd second the Radial recommendation. You need a load for the tube amp always. If you want it to be happy, and I think that you do.
Some other random thoughts:
* Parallel jacks are not the issue here. It's two amps running into an A/B, then out the A/B into one of the jacks of the cab. No one is suggesting shorting the outputs of the amps together. A OR B, not A AND B. Though some A/B switches have an AND function. That would be bad.
* If you have a passive A/B with two solid state amps, and the switch is break-before-make, then all is well. Make-before-break would possibly cause problems with poorly-protected amps.
Modern SS amps almost always have short-circuit protection, and don't have output transformers (unless it's some esoteric thing). So the open- and short- circuit issues are not a problem. I wouldn't recommend short-circuiting it for fun.
A passive A/B switch with no load is a bad idea. I'd second the Radial recommendation. You need a load for the tube amp always. If you want it to be happy, and I think that you do.
Some other random thoughts:
* Parallel jacks are not the issue here. It's two amps running into an A/B, then out the A/B into one of the jacks of the cab. No one is suggesting shorting the outputs of the amps together. A OR B, not A AND B. Though some A/B switches have an AND function. That would be bad.
* If you have a passive A/B with two solid state amps, and the switch is break-before-make, then all is well. Make-before-break would possibly cause problems with poorly-protected amps.
Huh? Sorry, the SABDDI does not accomplish what the OP wants to do. He has two heads that he wants to switch them back and forth to one speaker cabinet. How does a DI do this?
This [Invalid or Expired Link Removed] was my rig throughout most of the 90's. It came with a pair of XLR speaker cables. I didn't know why or much about it at the time but the head and the jackplates on the cabs had XLR and 1/4" jacks. I really don't know if the XLR's used heavier guage wire than a typical mic cord or not, I barely new what an ohm was.
This [Invalid or Expired Link Removed] was my rig throughout most of the 90's. It came with a pair of XLR speaker cables. I didn't know why or much about it at the time but the head and the jackplates on the cabs had XLR and 1/4" jacks. I really don't know if the XLR's used heavier guage wire than a typical mic cord or not, I barely new what an ohm was.
The issue with speaker cables vs. instrument cables is shielding and insulation. Speaker cables don't need to be shielded (because they're high voltage and not being amplified further, so hum pickup isn't an issue) and if they were, shorts between the conductor(s) and shield would be bad news. The conductors in speaker cables have thicker insulation in general than instrument cables, too. To prevent shorts.
