Active Speakers?

Bestgear · Post by **Bestgear** » Sun 08 Aug, 2004 12:27

Hi Folks

Removed NSF speaker last night to measure up for replacements and was very surprised to see that it was active!

I have never seen this before - the speaker has a big heatsink attached and a two channel amp inside! This obviously powers both front speakers.

Question is, is the head unit a pre out model, and the rear must have an amp too, (somewhere!) or is this amp driven from speaker out levels?

The head unit I have is just a standard BMW Business RDS casette with changer control.

The amp is marker Harmon, and I know for sure the whole music system is stock BMW... I guess they just made it for BMW.

If the headunit has line outs, has anyone used it with another amp? I would like to retain the stock factory look in this case, plus it deters any possible hooligans..

On a slight aside, anyone seen the wiring diagram for this setup? The ETM just shows a std setup and the "full blown" Harmon install, nothin in between.

I guess someone is going to come back to me and say they are all made this way!!

Thanks Chaps...

David

muffles · Post by **muffles** » Sun 08 Aug, 2004 15:21

by lineouts on the headunit do you mean the pre-outs? i assume you do, just checking cos you used the two different words. anyway - if it doesn't have pre-outs, you can get convertor boxes that change speaker outs to pre-outs, if you really want to keep the original head unit.

Bestgear · Post by **Bestgear** » Sun 08 Aug, 2004 18:10

Hi

Yes, line outs/pre outs, I used them as interchangeable....sorry.

I was just so very surprised to find a wee amp where I did... I guess I will open up the head unit and check to see if it does have an amp or line out only.

I thought that some folks must have tried the stock head unit with another amp before... Many OEM head units sound far better when fed through aftermarket amps and speakers... and if this does have real pre outs its a bonus!

David

muffles · Post by **muffles** » Sun 08 Aug, 2004 19:51

yeah if it had pre-outs it would be good, i could actually install all my audio gear then! hmmm, what are the chances it has 3 pre-outs

Bestgear · Post by **Bestgear** » Sun 08 Aug, 2004 20:31

Hmm... 3 pre outs... we all wish!!

It is unusual, as the front speakers have the two channel amp fixed to the nsf speaker, the rears have no amp, ie wired as expected.

So, my guess is that the nsf amp is driven from speaker level outs from the head unit...

I will check it out (removed amp to check circuit) and will see from the TDA8563 data sheet.

I guess BMW must have done this as an interim sound upgrade rather than select a new head unit at more cost.

Can anyone with the same basic cassette/rds confirm if they have an amp behind nsf speaker?

David

Zmeagol · Post by **Zmeagol** » Sun 08 Aug, 2004 21:26

Wiring diagram: http://www.zroadster.net/leftfrontactivewoofer.jpg

Correct, but this wasn't an interim solution! Amplified signal feeds rear coaxials and also goes to front crossover/active setup. There's a 12-way plug going into the setup that as well as carrying the input signal, distributes the separated signals for the other footwell woofer and the door tweeters.

Upgrading rear speakers: http://www.zroadster.net/tim/custom/index.html I never got around to documenting the front speaker upgrade. Basically you have a choice of ripping everything out and starting again, or mounting replacement speakers onto the active setup, which was the route I took.

Tim

Bestgear · Post by **Bestgear** » Mon 09 Aug, 2004 10:56

Many thanks for the links - that is the very circuit diagram I was looking for!

That one is not in the ETM I checked... I guess there must be a few versions around. It also does not show rear speakers, which is strange.

So - it clears up the other question too!

The head unit is not a line level (pre) unit, as the amp is driven from speaker level outputs. That is a big shame!

Thanks for your help.

David