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Bose B1200

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CJS-90 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote CJS-90 Quote  Post ReplyReply Direct Link To This Post Topic: Bose B1200
    Posted: 19 October 2015 at 3:05pm
Hello!

So I'm no expert with amplifiers hence this post.

I work for an IT recycling company and we've just had 2 x Bose B1200 amplifiers arrive.

I have a small PA setup myself so I used my speakers/mixer to plug everything in to test.

Now, when I test them:

1 x amplifier appears to be set up just for bass bins (as there is absolutely no treble, just punchy bass & a little bit of mid that comes out of my speaker)

1 x amplifier appears to be set up just for tops (there's literally no bass at all, only mid & treble).

This test was done with the same cables, same song (just playing from my phone) and speaker (only 1 plugged in). It's also the same with both channel inputs/outputs on each amplifier.

My question is: Were they like this from the factory?... because apart from a couple of small yellow stickers, there is visibly no difference between the amplifiers.

Any help would be greatly appreciated!

Kind regards,
Chris.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cravings Quote  Post ReplyReply Direct Link To This Post Posted: 19 October 2015 at 3:26pm
doesn't sound right.

these amps are MC2 made, think T1000.

what is the speaker you're using to test? there's no way it's a biamped speaker and you're somehow connecting to one set of pins and then the other? not using the middle out of the amp, just a / b?

those amps don't have any filter, so there's a problem somewhere.

check your speaker lead is 2 core, check it's joining pins +/-1 at each end on the speakon.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote James Cotton Quote  Post ReplyReply Direct Link To This Post Posted: 19 October 2015 at 4:32pm
Googling around it looks like there were filter cards available for these amps, maybe yours has them installed.
 
Looking at this ebay ad.....
 
 
There's a sticker on the back showing a 402 eq card installed on the A channel.
Any sign of stickers like these on your amps?
 
Not sure if the eq cards just applied a little eq to fix the Bose sound or if they were a full crossover card but it's worth a look.
Maybe whip the lids off and see if the cards are there?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote CJS-90 Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2015 at 1:36pm
To update this

I've just opened them up. One of them that appears to only provide lows looks to have a "Panaray MB/02" card, and the one that provides mides & highs has a "MA12 II Stacked" in there.

Does that mean anything to anybody on there? Google doesn't bring up much.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote CJS-90 Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2015 at 1:37pm
I thought I'd also add, I contacted Bose themselves and they didn't really give me much information. I just got passed around and given a few email addresses who never really gave me a clear answer, but kept forwarding to other people in different departments.

Thanks
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Post Options Post Options   Thanks (0) Thanks(0)   Quote imageoven Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2015 at 11:08pm
Iirc pull the cards out and you will have full range amps back again. There may be jumper links I'm not remembering - a photo would help
Keep pushing on, things are gonna get better.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 06 November 2015 at 11:48pm
Originally posted by CJS-90 CJS-90 wrote:

To update this

I've just opened them up. One of them that appears to only provide lows looks to have a "Panaray MB/02" card, and the one that provides mides & highs has a "MA12 II Stacked" in there.

Does that mean anything to anybody on there? Google doesn't bring up much.


The Panaray MB4 and MA12 are install components of a column array speaker system they have, I expect the crossover would be around 250-300hz. As suggested just pull the cards out and see if the amp passes fullrange audio, if not you may have to fabricate some jumpers to complete the circuits.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote simonp1100 Quote  Post ReplyReply Direct Link To This Post Posted: 07 November 2015 at 11:23am
Put up a photo of the inside of the amplifier and a few pics close up of the input cards.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bass*en*mass Quote  Post ReplyReply Direct Link To This Post Posted: 07 November 2015 at 12:20pm
i`ve had one of these amps years ago, also fitted with some PIP cards, if i remember correctly its really as easy as suggested, take the cards out and possibly switch a DIP..
(not sure on the DIP, once opened you will see it or not, its been a while since i had mine open)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Natedub Quote  Post ReplyReply Direct Link To This Post Posted: 03 December 2015 at 8:01pm
The Bose B1200 is a hybrid of the mc2 t1000 with the t1500 transformer. The crossover cards can be removed easily as suggested, cant remember the exact details but I contacted Mc2 at the time for help and they were very helpful.
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