400+ question

levis76 · #1 12-21-2010, 11:50 AM

Can I run a pair of headphones right off the preamp from the effects send if I turn the effect blend to 10 and master to 0? Not sure if there will be an impedance issue, the headphones are 55ohms and handle 3000mW. I know the V-Twin pedal has a mixer/headphone output on it, and this is basically the same preamp.

fenderhutz · #2 12-21-2010, 11:55 AM

When the amp is on it must carry a load from a cab. Didn't know if that was part of your equation.

RickenBoogie · #3 12-21-2010, 12:07 PM

+1 to the above, and no, I don't think the headphones wouold work anyway. Headphone out is a must, without adding other equipment to the process.

NecroticImbecil · #4 12-21-2010, 12:24 PM

400+ manual, top of page 3:

Quote:

...If you wish to use
only the preamp section of your Bass 400, you can use the Effects Send jack as a preamp
output; be sure to set the Effects Blend at 10 and the Master to 0. This will prevent signal
from driving the power section, so running the amp without a speaker or load resistor will
be OK.

Not that I'd ever actually try it myself.

http://www.mesaboogie.com/manuals/Bass%20400%20Plus.pdf

levis76 · #5 12-21-2010, 12:25 PM

Beat me to it Necrotic.

Just to be safe, I would leave the cabinet plugged in, but the master will be at 0 anyways, so no output. I think I might try it just to find out.

I haven't been able to find specs on the different outputs for the amp. I don't know what the ideal impedance for the effects loop out is or what kind of power. The headphones I have are rated for 3W at 55ohms.

BurningSkies · #6 12-21-2010, 12:26 PM

Quote:

Originally Posted by NecroticImbecil

400+ manual, top of page 3:

Not that I'd ever actually try it myself.

Yep. I know that's in the manual, but I've always questioned the reality of the statement.

NecroticImbecil · #7 12-21-2010, 12:32 PM

Could always call Boogie. Should be a phone number somewhere on the web site, though it can be tough to actually get someone on the phone.. tends to be "leave a message, we'll call back... eventually" which stinks if you have a job, or sleep, or what-not.

I'd imagine it would be possible to run the effects send into some device that accepts line inputs but has a headphone out, like a headphone amp, mini mixer, Korg Pandora, etc even if the headphones wouldn't work directly into the head.

Sounds like you have the right idea, keeping a cab plugged in just in case. Wish I had some actual helpful info...

levis76 · #8 12-21-2010, 12:37 PM

Looking at the V-Twin pedal, the headphone out is also a mixer out. The only thing close to a mixer out on the 400+ is the slave out, but that would require running the power section to get any output, which would defeat the purpose of running headphones. Hmmm, maybe I'll have to invest in a V-Twin pedal, which I could use anyways.

LiquidMidnight · #9 12-21-2010, 01:06 PM

Quote:

Originally Posted by BurningSkies

Yep. I know that's in the manual, but I've always questioned the reality of the statement.

+1

I'm pretty sure with the blend the whole way on, a minute amount of signal still goes through the power amp. Don't quote me, though, because it's been a while since I've done that with my 400+.

BurningSkies · #10 12-21-2010, 01:17 PM

Quote:

Originally Posted by LiquidMidnight

+1

I'm pretty sure with the blend the whole way on, a minute amount of signal still goes through the power amp. Don't quote me, though, because it's been a while since I've done that with my 400+.

I'd be less concerned about signal running through the power amp, and more concerned that without a load on the power side you're liable to take out your power transformer.

LiquidMidnight · #11 12-21-2010, 06:27 PM

Quote:

Originally Posted by BurningSkies

I'd be less concerned about signal running through the power amp, and more concerned that without a load on the power side you're liable to take out your power transformer.

I guess I should have been more clear. That was my point. There's signal going through the power section, which means a signal is hitting the OT with nowhere to go.

NecroticImbecil · #12 12-22-2010, 10:58 AM

Quote:

Originally Posted by levis76

Just to be safe, I would leave the cabinet plugged in, but the master will be at 0 anyways, so no output.

Looks like the OP shares these concerns and is planning on playing it safe. No idea though if plugging headphones directly into the preamp out would be safe, though.

Have you tried a VTwin with bass? I hated it, but then I was trying to use it more as an effect to add a little dirt than as a clean preamp. I found that it broke up too early and too much to be of use, but admittedly I did not spend a lot of time tweaking it.