Randall distorts

[T-bone]

hi people, can i get some advise on a randall rb 200x bass amp that distorts @ high vol, low vol dosent seem to worry it, but anything above 3 and it distorts bad.
cheers T-bone x

[Steve Conner]

You need to tell us more, in particular about "distorts bad" and "3".

Bad distortion for Stanley Clarke would be squeaky clean for Geezer Butler.

3 might well correspond to full output power if the amp were being driven by a high-output active bass. If the amp has an input pad or high/low input sockets, try those. If there are two volume controls, try the master wide open and regulating it with the preamp volume.

[T-bone]

cheers

thanks steve for your response. sorry i was so limited in info. this amp has duel inputs, for active and passive bass systems. it also has a seperate compression cuircit and eq section witch can be turned off. input gain @ min with active bass in active input with both compression and eq cuircit turned off, will still produce BAD distotion @ around 3-4.

HAVE TRIED PREAMP SECTION WITH DIFFERANT CABNETS, STRILL SAME OUTCOME! anyone got any pointers whwere i might5 START looking?

THANKS, T-BONE

[T-bone]

COFFE

Meant to tell you, input gain min is around 4-5 have adjusted these input gain and master a mutitude of ways, and it seems that @ very low volume, whether the compression & eq section is turned on or not, no problem, still get nice bass sound. But as soon as you turn the master up for more output, it starts distorting bad, not a hissing bad, but a blurting bass end bad heh heh if you can picture that.
Sounds like speaker prob to me, but ive tried it with differant cabs but still same, any ideas?

T-bone.

[Steve Conner]

Does it have preamp out and power amp in jacks on the back? If so, try plugging your active bass into the power amp in jack, and see if it'll go louder without distortion that way.

If it won't, then either your power amp is faulty, or the bass EQ on your active bass is turned right up. I've seen active basses that can be adjusted to put out enough bottom end to distort anything. I nearly exploded a little 15 watt practice amp that way, when trying out a Warwick in a music shop

If you do get a better tone this way, then either the preamp is faulty, or you don't like the tone of the preamp, or the bass EQ on your bass is turned right up as above...

[T-bone]

rock!

cheers steve, will try your suggestions. thank you so much for your response!

tbone

[T-bone]

distorted bass combo!! help.

hi people unfortunantly steve, this amp dosnt have a preamp out and power amp in, just an effects loop & footswitch inserts. turning the bass active cuircit down dosnt help lessen the distortion from the output, the more you turn the master up the more distortion you get, its almost like a distorted chanell from a guitar amp. any ideas were i should start looking mate?

t-bone

[Steve Conner]

Oh, well try plugging the bass into the effects loop return, and see how that goes. If it still sounds bad, then I'd take it to a repair place and ask them to check it out, and make sure the power amp is delivering the full 200 watts.

It wouldn't hurt to ask Randall for advice, if they're still in business.

One more thing, did you try a new speaker cable? Maybe it's shorted or has a loose connection.

When you tested with other cabs, were they the right impedance for the amp? Some amps go into protection mode with a 2 ohm load and make a weak, sputtery tone.

[T-bone]

distorted randall

thanks steve, this randall 200 watt bass amp is my amp that a freind gave to me, i want to try to fix this for myself as an electronics project. fixed quite a few amps previously, mainly just small things main caps replacement faulty transistors, bad ics etc, but my signal generators gone on the flck, so im wanting some ideas from anyone who has come up against this particular problem before, maybe give some possible checks so i can isolate an area just to save me some time! ive checked the amp against other bass quads of a similar confiquration, still same outcome. out put is 22.2 mv.appreciate some help with this project!!

[mac1amps]

It sounds to me like you may have the "Bass Combo" scenario. As convenient as it is, having everything in one unit, when you closely subject the electronics of the amp to the speaker vibrations of a Bass amp, it's just a matter of time before you start having loose connection issues. This is especially true with the way most "factory" soldering is done. Get out your soldering iron and check your power amp/ supply boards!