Bridging 2 Tube Amps

[Staccato]

Who uses (or tried) a bridge connection for 2 tube amps for gigs, or practice? Alternately, some connect a stereo pedal to 2 amps. Some do this for added stage volume?

Bridge: Connecting bass/guitar to amp that is equipped with two inputs. Second patch cord runs from input #2 to input of second amp.

The example below is NOT a bridge connection!
Serial: Output of one amp to input of another amp. (It can spell disaster, quick!)

[JimmyM]

my band's guitarist does this on the road when he's supplied two amps. i have no idea why, though. he does nothing special with it, and it only gets him dirty looks from bowzer.

[brendanbassist]

I didn't know connecting the second input to another amp would work. I always assumed there was a buffer circuit to prevent whats connected to one input from interfering with the other.

[BassmanPaul]

While you can bridge two identical tube amps it's a little complicated to do. Bridge is connecting a stereo power amplifier to operate both its channels into a single cabinet. What you are describing is running two amps in parallel. If the amps are identical you'll be fine. If not you may well be plagued with phase problems if one amp inverts the signal and the other does not.

Paul

[BassmanPaul]

Originally Posted by JimmyM

my band's guitarist does this on the road when he's supplied two amps. i have no idea why, though. he does nothing special with it, and it only gets him dirty looks from bowzer.

Sounds like Bowzer give out a lot of dirty looks!!

Paul

[silvertones]

AND double the wattage = 3 Db BFD

[BassmanPaul]

Originally Posted by brendanbassist

I didn't know connecting the second input to another amp would work. I always assumed there was a buffer circuit to prevent whats connected to one input from interfering with the other.

To a certain extent you are right. Some amps feed their inputs into independent buffer stages but most use a simple resistive divider which will give out a reduced version of the input signal.

It's just as easy to use a y cable. The OP might have ground loop problems but that's about it.

Paul

[edbass]

Originally Posted by JimmyM

my band's guitarist does this on the road when he's supplied two amps. i have no idea why, though. he does nothing special with it, and it only gets him dirty looks from bowzer.

Hmmm... maybe you answered your own "why".
It might be the same satifaction I get from the look on a FOH mixer's face when they see me plugging a microphone in the DI lead they laid on my rig.

[JimmyM]

Originally Posted by BassmanPaul

Sounds like Bowzer give out a lot of dirty looks!!

yeah, very true. he really doesn't want to hear anything but himself at excruciatingly loud volumes. not that i care so much...what i hate is getting blamed for being loud when it's obviously from the subs and my amp is nearly off.

[JimmyM]

Originally Posted by edbass

Hmmm... maybe you answered your own "why".
It might be the same satifaction I get from the look on a FOH mixer's face when they see me plugging a microphone in the DI lead they laid on my rig.

negative reinforcement is better than being ignored? could be.

[BassmanPaul]

Originally Posted by JimmyM

yeah, very true. he really doesn't want to hear anything but himself at excruciatingly loud volumes. not that i care so much...what i hate is getting blamed for being loud when it's obviously from the subs and my amp is nearly off.

I hear you! I got fired from a band when the leader bought himself an acoustic Telecaster. He was feeding back all night and kept telling me I was too loud. At the time he finally fired me my bass was turned completely off!

Paul

[Staccato]

There must be some weird stories over the years from guitarists plugging the wires every which-a-way...