amp noisy - when in switcher

[one less than none]

I have a Mesa Boogie Dual Rectifier Rackmount head fed from a Sound Sculpture Switchblade GL (fantastic bit of kit).

Unfortunatly the Boogie is very noisy when fed from the switchblade, if i plug my guitar direct into the head all the noise dissappears (well except on mega high gain settings and even then it is much much quiter).

But i dont want to do this as all my pedals and fx are in the switchblade as well as my other amps.

Does anyone know why the head might be noisy when it is in the switcher ? and yes i have checked the cable (and replaced it) my other amps (marshall JMP-1 and EL34 power amp) are fine

(Edited by one less than none at 8:09 pm on Oct. 8, 2001)

[Gresh]

Get on the phone with Mesa Boogie, they will totally hook you up with what could be going on...their customer service is legendary...

[Platypus]

Does the Switchblade really work with instrument signals? I thought it's just used to switch effect (in the effects loop) in and out of the signal chain.

[one less than none]

yeah the switchblade works fine at instrument level.

The sound sculpture website for more info on the switchblade GL if you are interested. it does have 4 switches for fx loop on/off and channel switching but it is mainly a signal router and distributer.

All my other gear has become quiter since going in the switchblade, i can't understand why the boogie has done the opposite......

[7 Dying Trees]

The thing to have a think about is how much noise the switchblade produces. Anything electronic is going to up the total amount of noise in the signal path, and nothing is going to change this (pretty much something you have to deal with), but what is especially important is that anything that produces noise should be placed after any kind of preamp. Preamps are very high gain, and will not only amplify your signal, but any extra noise introduced. As you've said that the meas is OK without the switchblad in it's path, and goes noisy with it makes me think that the switchblade is adding enough noise to your signal for you to notice it. If possible put anything noisy after any preamp stage...Switches are inherently noisy devices, so you might find it's a problem that's very difficult to get the desired solution out of. Try maybe doing some electrical/elctromagnetic isolation on your entire rack to stop signal interferance between all components (I think JP has his done in some way to minimise interferance).

Hope this made some sense...

[one less than none]

doh ! i used the word noise instead of hum !

sorry the amp hums.....

i have everything in my rack connected to the same power supply, so i dont thing it is ground loop hum.

anyway switchblade specs :

the THD level is 0.006% and crosstalk is -90db, while dynamic range is 106db.

so i dont think the noise should be coming from there ...... maybe it is ground loop hum

I have seen a samson powerbrite power regulator for £75 maybe that would help ?

Or is it the cableing

i have emailed boogie and sound sculpture to ask them about the problem.


(Edited by one less than none at 11:00 am on Oct. 10, 2001)