Using more than one input at the same time.

[The Rage]

On my SWR I often use both inputs at the same time, but the manual states that is safe.

 

[Lizooki]

I know what the active side is for.
I did read the manual, but it did not reference them other to say one was padded, the other isn't.
I do have a more than average understanding of electronics and I also saw the block diagram which is WAY too simplified. It also shows both running through the pad.
I really didn't think it would hurt anything, but figure more experience minds would have a better idea.
I'm pretty sure the Acoustic combos are engineered to be idiot proof for the most part.

 

[agedhorse]

It probably won't hurt anything but it probably won't help anything either.

 

[zombywoof5050]

Ok, sorry if this is considered a thread hijack, but it is related (using both inputs) so I thought to ask here.

I have an Alembic F-2B preamp, and I came up with what I thought was a great idea.
The Alembic F-2B has two channels (A & B) each with 2 inputs (input 1 is normal and input 2 is -6dB).
I plug my pedal board into Channel A input 1 (signal from pedal board is unity gain with volume of bass), and the Channel A output goes to the poweramp of the stage rig. Then for a DI, I run a short cable from Channel A input 2 into Channel B input 1 (this is just to get the same signal going into the inputs of both channels). Then I go from the output of Channel B into a Radial JDI for FOH. Before I tried this, I assumed that running the cable from the A to B inputs might cause a signal level drop, but it doesn't and it works perfectly. The beauty in all of this is I can change the volume/EQ on my stage amp (Channel A), and it has no effect on the volume/EQ going to FOH (Channel B), and the signal going thru the F-2B into the JDI is acting just like a good tube DI (with EQ capabilities too).

I don't gig much at all, and I've only run it like this a few times, but it seems to work beautifully.

My question is...Am I hurting anything by running it this way?

[Invalid or Expired Link Removed]

 

[zombywoof5050]

Oh well, looks like I killed another thread, sorry.

 

[Mechayoshi]

Peavey stuff will say in the manual that you're free to use both, only both will be the lower padded volume.

Those labels are lies. There is no direct correlation between presence of a battery in your bass with output level.

Always try the 'passive' input first with every bass. Only use the 'active' input if you get unwanted distortion with the 'passive' one.

Exactly. And I've yet to have an input distort even with very hot instruments anyway.

 

[butterfingers1]

Say I have 4 passive bass guitars, and I want all 4 plugged into the passive input, just so I don’t have to plug/unplug every time I switch bass. Is this possible? Surely there must be simple adaptors for this, like home electric outlets.

 

[agedhorse]

Say I have 4 passive bass guitars, and I want all 4 plugged into the passive input, just so I don’t have to plug/unplug every time I switch bass. Is this possible? Surely there must be simple adaptors for this, like home electric outlets.

No, the pickups will load each other down and the results will be horrible.

 

[Redbrangus]

You'd need some way to isolate the load (impedance) of the unused instruments from the passive pickups of the instrument in use. That takes active components, or a resistive network that would significantly and adversely affect the already miniscule signal of a passive instrument. Short answer: no.

Late edit: I see @agedhorse weighed in, so.... there ya' go.

 

[butterfingers1]

Thanks.

 

[butterfingers1]

So if I just plug 2 (passive) bass guitars in the 2 inputs (active passive), playing only one at a time, this should be fine, any disadvantages?

 

[Redbrangus]

Hmmm... I guess if the volume control for the bass not in use was turned all the way down, that would work. The one plugged into the active input would be obviously quieter, but there are ways to compensate for that, I guess. And of course, the two "inputs" are sharing the same EQ and the rest of the signal path. I'd say test it out and see if it works for you. It's not like you could blow something up or anything.

 

[agedhorse]

There will still be loading issues on most circuits.

 

[SteveCS]

...and you know: a car has so many 'inputs' for liquid stuff --- why not put gasoline in all of them...vrrroooom....!

or ......Boooooom!

 

[JRA]

 

[butterfingers1]

There will still be loading issues on most circuits.

Even if only one bass is used at a time, the other having its volume off? I would do this to avoid frequent plugging/unplugging to switch guitars.

 

[agedhorse]

Even if only one bass is used at a time, the other having its volume off? I would do this to avoid frequent plugging/unplugging to switch guitars.

Yes, with the volume turned down on the bass, the input sees a short circuit looking at the bass.

Even with the pad resistors in place on a typical 2 input amp, it will load down the other input.

There are exceptions, but they are fairly rare.

 

[Redbrangus]

Well there you go...straight from the horse's mouth. So to speak. I hadn't truly considered the effect of the shorted input on the other half of the circuit. It sounds like an argument for buying an A/B/Y box; they're cheap.

 

[beans-on-toast]

I’ve seen custom built A/B/C/D/… buffer switch boxes from Pete Cornish. Multiple in one out.

 

[butterfingers1]

There are passive and active ABY pedals, any recommendations? I’m looking at ART Pro Audio.