Braun LV1020 Active Speakers- Restoration

[TellMeWhy]

Dear Friends,
Today I was lucky enough to acquire a pair of Braun LV1020 active speakers- huge, impressive beasts from the early 70's with internal tri-amping. They cost a fortune in their day, and seem to be in original and very clean condition inside and out.

But the sound is way of what you would I expect, which I am assuming is probably down to 45 year old electronics. I have done the usual clean up and deoxit, but it didn't effect any change. I have also checked and changed connection cables.

One speaker has a constant buzzing (mostly on the tweeter channel), even with no source plugged in, which I suspect is probably down to a bad transistor (BC157a), but I am no electronics ace, and it could be a bad cap or loose joint.

So my question is- is it worth giving the amps to my tech to recap and over hall them? The boards are easy to remove and to work on, but hard to test (without being plugged into the speaker units). I guess that would end up being quite an expensive operation.

Or do I get an active crossover, buy 3 new amps and use them like that?

Or do I try and find a similar used Braun or ADS crossover and see how that works?

What would you guys do- they are quite a stunning pair of speakers....

Nice evening,
Jon

 

[Drugolf]

Take them to your tech first and see if he thinks the fix will be easy enough. Will be difficult to find another Braun or ADS crossover/amp set-up.

 

[onwardjames]

Agreed with Drugolf. See what can be done with what you got. Nice find!
Pics if you have time, please.

 

[elcoholic]

Dear Friends,
Today I was lucky enough to acquire a pair of Braun PV1020 active speakers- huge, impressive beasts from the early 70's with internal tri-amping. They cost a fortune in their day, and seem to be in original and very clean condition inside and out.

But the sound is way of what you would I expect, which I am assuming is probably down to 45 year old electronics. I have done the usual clean up and deoxit, but it didn't effect any change. I have also checked and changed connection cables.

One speaker has a constant buzzing (mostly on the tweeter channel), even with no source plugged in, which I suspect is probably down to a bad transistor (BC157a), but I am no electronics ace, and it could be a bad cap or loose joint.

So my question is- is it worth giving the amps to my tech to recap and over hall them? The boards are easy to remove and to work on, but hard to test (without being plugged into the speaker units). I guess that would end up being quite an expensive operation.

Or do I get an active crossover, buy 3 new amps and use them like that?

Or do I try and find a similar used Braun or ADS crossover and see how that works?

What would you guys do- they are quite a stunning pair of speakers....

Nice evening,
Jon

AFAIK these are unique. I’ve heard them a few times and even after 30 years since the last time they are stunning. Please restore to original specs or pass them along to someone that will.

 

[nolasally]

I have the same set. Mine was missing one of those amps. I bought a set of ads L980 crossovers for them and pulled out the other amp. Crossover in 980 uses same driver components.

 

[TellMeWhy]

Thanks guys. Will definitely have them professionally checked over. Quick question in the meantime- the 7 pin DIN connectors... pin 1 and 7 are redudant as far as I can see, so it's fine to use regular 5 pin DIN or?

 

[baco99]

The LV-1020 or PV-1020?

 

[TellMeWhy]

The LV-1020 or PV-1020?

LV1020.... I also have CES1020 here...

 

[baco99]

LV1020.... I also have CES1020 here...

ok, your original post said PV-1020 and I had never heard of that model.

The LV-1020 is a very special speaker. I would highly highly recommend spending the time and expense to have the amp boards recapped, solder joints reflowed, and have the multi-pin connectors adjusted to make sure they make good contact. It's well worth it. There are schematics online. I assume from your location in Berlin that your tech reads German! The DIN cable to RCA cable adapters can be purchased online either from Amazon or Monoprice in the US.

 

[TellMeWhy]

Y

The LV-1020 or PV-1020?

Yep, exactly like that

 

[TellMeWhy]

ok, your original post said PV-1020 and I had never heard of that model.

The LV-1020 is a very special speaker. I would highly highly recommend spending the time and expense to have the amp boards recapped, solder joints reflowed, and have the multi-pin connectors adjusted to make sure they make good contact. It's well worth it. There are schematics online. I assume from your location in Berlin that your tech reads German! The DIN cable to RCA cable adapters can be purchased online either from Amazon or Monoprice in the US.

Sorry, was a typo, now corrected! Is it OK to use 5 pin DIN connectors rather than 7 pin?

 

[baco99]

Sorry, was a typo, now corrected! Is it OK to use 5 pin DIN connectors rather than 7 pin?

no, the pin out is different.

For the right and left speaker you will only use 3 of the 7 pins in each connector. but the alignment has to be right to get the polarity right. you will see in the schematic.

 

[TellMeWhy]

no, the pin out is different.

For the right and left speaker you will only use 3 of the 7 pins in each connector. but the alignment has to be right to get the polarity right. you will see in the schematic.

Oh I see, so they must be differently wired cables? Even a 7 pin cable wired pin to pin is not correct? I can see it in the schematic but never realised it would require custom wired cables!

 

[dr*audio]

What is the condition of the surrounds on the woofers?

 

[TellMeWhy]

What is the condition of the surrounds on the woofers?

Perfect. Like new- heavy duty rubber

 

[baco99]

Oh I see, so they must be differently wired cables? Even a 7 pin cable wired pin to pin is not correct? I can see it in the schematic but never realised it would require custom wired cables!

No, it doesn't require custom wired cables. A 7 pin to RCA adapter will have a L and R input. So you can use one type of cable. Just depends on whether you tap into the L or R on the speaker itself.

 

[baco99]

https://www.amazon.com/CablesOnline...d=1537706572&sr=8-5&keywords=7-pin+DIN+to+RCA

 

[baco99]

Perfect. Like new- heavy duty rubber

You are lucky. I have had both types, rubber and coated foam.

 

[TellMeWhy]

No, it doesn't require custom wired cables. A 7 pin to RCA adapter will have a L and R input. So you can use one type of cable. Just depends on whether you tap into the L or R on the speaker itself.

Ok, I am a little confused! But if I use 7 pin cables from the ces 1020 to the left speaker, a 7 pin din cable linking the speakers and a regular din to rca adapter into the ces, all should be fine?

 

[baco99]

I think pins 3 and 5 determine R or L.