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View Full Version : ALTEC LANSING ELECTRONIC CROSSOVER BIAMP MODEL 770



butthead
01-13-2007, 09:04 PM
I just got this unit. It says it a electronic crossover biamplifier. It is apparently two amps in one unit. It appears that you power your woofer with the 60 watt section and the tweeters with the 30 watts. Does anyone know much about these? Any clue to its worth? Any help would be appreciated.

johnaec
01-14-2007, 07:33 AM
'Sounds similar to the 771: http://www.lansingheritage.org/images/altec/specs/pro-systems/1209a/page2.jpg

I used to own a couple Altecs that I believe included the 770/771, ('looked the same). 511B and 421A drivers. We eventually replaced some onboard capacitors with a different value, (don't ask me which ones - it was an electronics tech that figured it out), because the stock ones would cause a very harsh "snapping" if the amp was overdriven - this change somehow resolved that.

We used them for years, with no other problems at all. I finally sold the pair, (complete cabs/amps), for $300, (didn't know any better... :banghead: ).

Here's a pic, (that's me in the green hat - mid 80's):

John

arawak1969
01-22-2007, 10:09 AM
I just got this unit. It says it a electronic crossover biamplifier. It is apparently two amps in one unit. It appears that you power your woofer with the 60 watt section and the tweeters with the 30 watts. Does anyone know much about these? Any clue to its worth? Any help would be appreciated.

The Altec biamp units wer offered in the home hifi and pro speakers in the early to mid 70's. I have 2 pairs of 771b's and 771BX's. They have tow amplifiers inside and a 12db electronic crossover that is switchable between 500hz, 1200 or 1500z.
The unit you have should have an RCA input jack instead of 1/4" jack.
If you are not aware of the benefits of baiamping, I would suggest you read up on it. It basically seperates the HF and LF electronically and reduces interference between the two resulting in cleaner sound.
I have 9846's and 878b's now and the difference is stunning in the clarity and detail.

There is another 770 on ebay right now. Is that yours?
Drop me a line if you have any questions.
Peter:dj-party:

NEVER_SELL_THEM
02-08-2007, 02:12 AM
I own a pair of 9846As and always wondered how would I go about bi-amping. Would one have to pull out the crossover unit or drill holes to pass the speaker leads, or what? Is there a clean solution? I read about external active crossovers, but that poses the same problem. I'm concerned about keeping the 9846 as original as possible. I do find that they lack low frequency power (at low power, normal perhaps?) and read that bi-amping is the solution. Any suggestions about what amps or gear to use will be appreciated.