Marshall IBS 3520 - How to Bi-amp?

[Billy Backbeat]

My first thread on Talkbass!

Bought an old 3520 quite cheap, partly because of the bi-amp feature. And now I can't figure out how to set it up to be able to use it in bi-amp mode. I have read the manual and it has some patching examples, but it's for the 3540 model (400w) (so I have tried to RTFM already) . None the wiser.

Do I need patch-cords? Links to schematics and manual below (schematics is wasted on me)

I have read threads here on talkbass that indicates that a couple of members in this forum has some experience of these old amps. The previous owner had not tried to bi-amp so no help there.

So: Can anybody me?

Gear:
J-bass (MIM) with flats, SansAmp BDDI, a TKS 1x12 (very small swedish one man company, sounds great) and a cheap used MAG115T (I want to use it as a "sub" and get the most of the sound/volume from the TKS 112)

(I'm Swedish so bear with me in the language department)

http://www.drtube.com/schematics/marshall/ibs.pdf
http://www.drtube.com/schematics/marshall/3520pre.gif
http://www.drtube.com/schematics/marshall/3520pwr.gif

[jastacey]

I had one of those amps years ago ... yes, you need patch cables, there are 2 separate built in amps @ 200 watts RMS, just follow the patching diagram, as a side note the Marshall IBS really didn't work well for me, to get maximum power you had to use 2 - 4 ohm cabinets, and if you used one of the built in amps for the bass, in BI-Amp mode it was kinda lacking. not enough power ... they use a really weird power transistor that is really hard to find, and that's how my amp meet the amp junk yard

[Billy Backbeat]

Originally Posted by jastacey

...yes, you need patch cables, there are 2 separate built in amps @ 200 watts RMS, just follow the patching diagram, as a side note the Marshall IBS really didn't work well for me, to get maximum power you had to use 2 - 4 ohm cabinets...

Thanks for the reply.
Sounds like you had the 3540 (2x200 watts)? If I had one of those (3540) i could easily follow the patching diagram but there are no diagrams/examples for the 3520 in the manual I have. The outputs in the back are different between the two.

...and yeah I have read about the power issue/problems with spare parts but i haven't had those problems (yet) as the band I'm in isn't all that loud (reggae with jazz people, I just try to keep up ) and I've only had it for a couple of months.

My technical skills are nonexisting so I will need more detailed help ("patch cable from A to B, speaker cable C in output D" etc.).

Anyone?