Advice please!

[sunita]

I have a gallien krueger 1001rb m1 which i used with my mb112 extension speaker. The head has given me a few problems in the past and this time I was told the transistors had blown. The repairers suggested the speaker could have caused this however i use it all the time with my mb112e combo and other heads and have never had a problem. Any suggestions as to why the transistors blew up?

 

[Alex1984]

How many cabs did you hook up to it?

 

[sunita]

just the gk mb 1x12 cab (90w/8ohms)

 

[Slowgypsy]

Wow... that's a lot of amp for that speaker. What are your amp settings? And did you purchase this amp new or used?

 

[billfitzmaurice]

Any suggestions as to why the transistors blew up?

No, but I do suggest you find a more qualified repair shop.

 

[sunita]

Purchased the head new 9 years ago, used it less than 10 times. Amp settings - gain 1 o'clock, woofer volume slightly more. Used the jack input instead of speakon..

 

[Slowgypsy]

Purchased the head new 9 years ago, used it less than 10 times. Amp settings - gain 1 o'clock, woofer volume slightly more. Used the jack input instead of speakon..

I'm having a hard time accepting the combination of that amp, those settings, and that cab... speaker would have blown early on. That's a waaaay powerful amp into a itty-bitty cab. I actually own that cab, and it would not take that kind of volume.

Is this the first time that amp has been brought to a shop?

 

[Eric Moesle]

My first thought is that it sounds like a short in the speaker cable could have caused that damage.

Where you using a proper speaker cable, or were you using an instrument cable? If you used an instrument cable between the amp and cab, the foil shielding inside the cable could have melted under that much power causing a short, which could have fried your transisitors (maybe).

Just brainstorming here.

 

[Slowgypsy]

just the gk mb 1x12 cab (90w/8ohms)

Do you mean the GK MBX112 which is the extension cab for the MB150E combo?

 

[BassmanPaul]

Purchased the head new 9 years ago, used it less than 10 times.

Amps, like all things electronic, need to be powered up on a regular basis. I feel that your speaker cabinet had nothing to do with your amp failing. I'm thinking the lack of use caused the problem.

 

[Jay2U]

Maybe the coil of the speaker got overheated, so that some of the insultion material has molten. This would short circuit some of the windings, reducing the impedance and eventually killing those power transistors.

Keep on playing subsonically!

 

[WhoDidTheElf]

Purchased the head new 9 years ago, used it less than 10 times. Amp settings - gain 1 o'clock, woofer volume slightly more. Used the jack input instead of speakon..

Less than 10 times in the last 9 years? That might be your problem. Amps like cars can't just sit unfortunately.

Also, I have a good feeling your cab is blown. Those settings on that cab must have blown it.

Have you tried a different cab or different cable? Different bass? Try all of those first.