Stock HK amp crossover frequency?

[tigerdog2000]

I've read about a zillion posts and used the search function, but I have not been able to find the following information:

• Crossover frequency (and ideally, slope) between front kick-panel speakers and door midtweets?
• impedance of door mid/tweet speakers

Does anyone know this info offhand?

[delvec]

I don't know the crossover but The door tweeter is 4ohms at 4 watts and the mid is 2 ohms at 20 watts.

[tigerdog2000]

I don't know the crossover but The door tweeter is 4ohms at 4 watts and the mid is 2 ohms at 20 watts.

Thanks for this info. Are the power figures the speakers' power rating, or the power output of the HK amp in the trunk?

[delvec]

Thanks for this info. Are the power figures the speakers' power rating, or the power output of the HK amp in the trunk?

It's the actual power rating for the door speakers.

[tigerdog2000]

It's the actual power rating for the door speakers.

Thanks, Delvec. One of my mids has died. I will replace with something suitable, but without knowing the co frequency and slope, it's a little challenging to make an educated selection.

[Solarphil]

Let us know if you find a replacement for the door mids - it’s a really unusual size. I’m usually pretty good about searching, cross referencing specs and massaging larger speakers into stock locations, but I was stumped trying to find a replacement for the mids. I wound up keeping the stock mids even though I swapped every other speaker in the car. Not ideal, but the best I could do.

Happy hunting....

[tigerdog2000]

... I wound up keeping the stock mids even though I swapped every other speaker in the car. Not ideal, but the best I could do..

I was thinking of replacing the door mids and tweets with a small wide-range speaker. With car background noise, and my ears, anything above 10-12K is wasted anyway. Something linear from 2-10K might be OK. But I really wish I knew the crossover characteristics... I'll let you know what I settle on.

[tigerdog2000]

Related question: can the door mid/tweet panel be removed from the outside, or do you have to remove the door panel to replace the drivers?

[z3forlife]

You’ve got to pull the card off. There’s a screw holding the speaker pod in the door card. The grill has tabs bent over so I doubt you remove it without pulling the card off.

[tigerdog2000]

You’ve got to pull the card off. There’s a screw holding the speaker pod in the door card. The grill has tabs bent over so I doubt you remove it without pulling the card off.

Great info. Thanks for the quick response! I guess I need to buy some plastic trim removal tools now...

[Trademark1]

Just had mine apart - here is the back of those speakers in case helpful for you to visualize (including what I think is screw holding grill on). 4CCD47D9-16B2-4B8A-A9B5-52964EFF857A.jpg

[tigerdog2000]

Just had mine apart - here is the back of those speakers

Wow, thanks for this! Now I can see exactly what I'm up against.

[cyberman]

But I really wish I knew the crossover characteristics.

Didn't notice this recent post. I don't think the stock amp has any crossover characteristics at all. I think it just pumps everything to the speakers and they adjusted relative power (output level) by using differing resistances (2 ohm in the small door-mounted, 8-ohm in the larger door-mounted and 4 ohm for the kick panel speakers.

In the kickpanels, I just threw in some 4 ohm el cheapo BOSS BE524 I picked up for $30 at autozone because they owed me $20 and just as an interim fix until I get around to replacing everything audio as the OEM speakers sounded really muddy. Now, I'd read earlier posts saying that one shouldn't put in component speakers in the kick panels since the built-in tweets couldn't respond as there was no power in their frequency ranges. But I tried it anyway, and guess what? They're pumping out very high frequencies fed from the amp as good as or better then the smaller ones in the door.

I'm not getting as much bass as the unusable OEMs, but that bass was so awful that it made the system horrible. The doors sound fine still, but I can't see anything that would make me say the OEMs were "blown", i.e. no physical damage is apparent. They look fine, but obviously either something is wrong with them or the factory setup was worse than I can imagine.

I'm coming up with a new, lower cost plan. I may just replace the head unit if an adapter to the existing wiring harness can be found. I'll jettison the in-trunk CD juke box (or give it to someone). I never forgot the sound of my 1974 pioneer 3-way 6 X 9's in my MG mounted behind my torso in the trunk/cabin cardboard divider. They had all the range and bass I needed. Since the top lid of my storage compartment is blown, and I want to retain my "cosmetic" rollbar that only serves to hold a wind-deflector, I'll remove it and build a box to hold two 6 X 9's. Then I'll get a small amp (~100 Watts), put in the trunk and splice into the head unit's kick-panel output to and use the little amp to power my 6 x 9's. I don't know if the newer head units with a harness adapter supply line level to the stock amp, but assuming they do, I'm in business. So, in the end, the stock amp will keep supplying the existing speakers and the new second amp will power the bigger ones in the back.

[rasmuw]

I'm not getting as much bass as the unusable OEMs, but that bass was so awful that it made the system horrible. The doors sound fine still, but I can't see anything that would make me say the OEMs were "blown", i.e. no physical damage is apparent. They look fine, but obviously either something is wrong with them or the factory setup was worse than I can imagine.

When I purchased my M, the only speakers that made sound were the kick panels and the small speaker behind the seats. I found out that it was the head unit, the original C43, was powering those speakers. The solution to my audio problems began with finding a used stock amplifier, as the original was literally fried. While they were still available, I purchased the Bavsound upgrade. Upon replacement, I found the mids behind the seats had cones with no connection to the frames. The kicks made a huge difference as well. Like you, Claude, my stock speakers showed no damage, but they couldn't hold any bass. I haven't yet removed the door cards to replace the tweeters there with the Bavsound version. I've since removed the C43 for a CD43 (wish it didn't skip on big bumps). Do I wish the amp didn't have so much distortion and that the subwoofer had more oomph? Yes, but what I do hear now is so much better for the amount of time and money I've put into the system.

[tigerdog2000]

Didn't notice this recent post. I don't think the stock amp has any crossover characteristics at all. I think it just pumps everything to the speakers and they adjusted relative power (output level) by using differing resistances (2 ohm in the small door-mounted, 8-ohm in the larger door-mounted and 4 ohm for the kick panel speakers.

I find this difficult to imagine - sending a full-range signal to that 1/2" dome tweeter would fry it in an instant... the 2 ohm impedance would simply allow more current, frying it faster. If I had an easy way of running spectrum analysis, I'd feed a white-noise signal into the head unit and measure them myself... but I would need to cobble together such a setup. Part of me thinks it would be more effective just to replace the HK amp with something contemporary, either with electronic XO or DSP or both. But that's probably more bucks than I want to drop into the system.

Head-unit replacement is simple, especially if the replacement head unit has DIN pinouts (e.g., Kienzle, Blaupunkt) because DIN-->BMW adapters are available pre-made if you search ebay or amazon. Alternately, the mating connector for the chassis harness is also available and can be mated to whatever connector comes with the replacement.

[cyberman]

and the small speaker behind the seats

You're lucky: you've got those holes/speakers. My first year model just has the kick panel speakers and two speakers in each door. So, I'm at square one of getting decent sound. My rear storage box lid was cracked beyond repair so it's been removed. My first thought was to build a new lid with a top mounted speaker or two as I have a much wider lid on mine than later models with provisions for built-in roll bars. But, I'd prefer speakers pointed towards me rather then the sky. My preference is for classic rock which doesn't require the booming bass of a true subwoofer, just reasonably low frequency response obtainable from 6 x 9's in spades. Part of my problem is that I have a "cosmetic" roll bar that has a cross member immediately above the storage lid (or the place where the top storage lid would be if I had one.

I find this difficult to imagine - sending a full-range signal to that 1/2" dome tweeter would fry it in an instant

Maybe the speakers in the doors have some kind of cross over setup in the stock amp. But, at least in my case, the kick panel speakers are getting a full range and the little "mid" and "tweeter" mounted in those speakers are responding and putting out a glorious sound, albeit maybe too bright. I agree that replacing the stock amp is a better idea in the long run, but for me cost is a big factor right now, and my plan would allow replacing the stock amp down the road. That decision will come based on cash flow and the sound I get from the 6 x9's, as well as how long that stock amp works. I'm amazed that after 25 years it works, but nothing lasts forever except death and taxes. Thanks for the info on the head units and harness adapters. So, I figure I can squeeze out a new head unit, small amp for the 6x9's, a harness adapter and misc. hardware for $400-$500, at least for now. Then, if I want better sound, a new amp to replace the stock amp and my add-on amp, maybe another $150 or so... that said with no research. This project (the Z3 as a whole) is one of continuous improvement. Today, for example, I have to break out my bore scope to inspect and figure out how to cure a nasty rattle in the driver's side door - probably no cost except in time. And thanks to the pandemic, I've got more time than cash in my bank.

[cyberman]

Revising my plan after driving an hour with the new speakers which are clear enough to "explain" the problem. That stock amp is a piece of shit and I can hear it's distortion starting at moderate volume levels. And, as the volume is raised, it produces a screeching crescendo that is simple breathtaking in its ability to turn music into something akin to a roof falling on an orchestra.

So, for now, new head unit, new amp and my 6x9's. New components highlight the weaknesses in old components (as happened today), so I'm sure the door speakers will eventually meet the doom of the garbage dump.

[tigerdog2000]

Still looking for diameter of door speaker holes (yellow) and mounting point centers (blue). Bueller?z3speakerHoleSizes.jpg

[s8ilver]

Still looking for diameter of door speaker holes (yellow) and mounting point centers (blue). Bueller?z3speakerHoleSizes.jpg

I'll grab these measurements later this evening for you. I'm about done with my retrofit.

Grills removed due to disintegrated cloth material. Thinking up solutions, and whether or not to source a new midbass for the 1 7/8" speaker (hint: that's about the size of the larger opening).

[z3forlife]

I’ve found that my MBQuart tweeter is more than enough by itself and fits the midrange hole perfectly. I removed the grill and inserted from the front. I left the stock tweeter installed but not connected. It’s more than “bright” enough

[tigerdog2000]

Did you replace the tweeter (left)? If yes, what did you use? Also, does the HK system run two sets of speaker wires to this array, or just one with a passive crossover (cap, etc.) in the back?

[df925]

Frequencies (dunno if it is correct or not)
STwt 1" - 3.5K - 20K(Passive X-over)
LTwt 2"- 1.5K - 3.5K
Door Panel 5.25" - 100 - 1.5K
Behind the Seat 3" - 200 - 1.6K
*info from http://www.mz3.net/articles/070.html

Since we are talking audio, any thoughts on JBL DSP4086?, 8 channel DSP

[z3forlife]

I did not replace the stock tweet and did not connect to my new system. My tweet fits in the mid hole. There are separate pairs to both speakers so you could conceivably install a 3 way component speaker kit for the 2 pod and 1 kick panel speakers but they may be a bit pricey. The crossover for the component setup would go in the trunk near the amp/harness. Of course you would have to cut the harness or salvage a plug from a stock amp to make a adapter.

[s8ilver]

Speaking of stock connectors, procured some Coupe amp plugs. My plug and play vision is coming to fruition.

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[IndianaRoadster]

Speaking of stock connectors, procured some Coupe amp plugs. My plug and play vision is coming to fruition.

Sent from my SM-G975F using Tapatalk

That reminded me of an old saying "where there is a will, there is a way".