I plan on updating this thread with diagrams and filter info in the near future. I am currently enjoying an Alpine MRP F300 powered system from the HK head unit. I will include photo's etc.

Terry

 

So wait, this Alpine MRP F300 is a direct swap out for the HK amp ? Im not good with electrical, so wondering if its something i can swap out or should i just go to a local stereo shop

 

yea what he said, is that possible???

 

I doubt this will work.

 

According to the posts by this thread starter, it has worked. Read from the beggining. I'll keep reading up on this as no music in the car is driving me nuts

 

A few notes for those who want/need to do the same. I decided to do one, not because I had to but because I wanted to use the HU I took out of my last car; which got totaled, oh well at least I got to keep the HU. Credit where credit is due: I patched together the notes on NAM (with Liquid Yellow and CooperCooper) to get started, I credit my success to their work and GBMini.

Specs on the HK speakers (2005 convertible) as measured at the amp connector with a conventional multimeter:
Front tweeter 3.2 Ohm
Front midrange 3.2 Ohm
Rear midrange 2.4 Ohm
Rear woofer 2.4 Ohm

Following determined using the HK amp with a Bink Audio Test CD (and my ears)
Front tweeter/mid crossover at approx 2500 Hz
Tweeter maxes out at 12,500 to 16,000 Hz
Mid starts to kick in at about 125 Hz
Rear crossover doesn’t appear to be significant, runs from 50 to 8000 Hz

Replacement equipment:
Alpine digital media receiver (used, previous ride)
Mini adapter plate
Euro Antenna Adapter, OEM F to Motorola M
Alpine to Mini harness adapter
JL Audio XR650-Csi/570 PXO Crossover (purchased used)
Sony XM-4S 50W x 4 Thin Car Amp (it’s powerful enough and it’s mini so it fits in the original amp box with the x-overs)
You can figure out which parts are needed by letting the Crutchfield site "outfit" your car for a new HU and then buy it wherever you want. However, it won't pick up the crossovers, you'll have to find a pair either new or used. The ones I used work fine, $50 used for the pair. These are "marketed" for 5.75 to 6.5 inch woofers with x-over at about 2500, 4 Ohms. The install instructions from Crutchfield are actually quite nice.

Nutshell:
Connecting the rear voice coils in series results in a resistance that is within the range of the amplifier and since the amp has independent rear and front level adjusters it works fine. When I tested the two rear speakers independently of each other I couldn’t hear much of a difference in frequency response—not sure why they put in two on each side—it just cost more?. The crossovers were used without modification on the front speaker pair as you might expect. The crossovers and amplifier fit into the existing amp box located under the passenger seat. The threaded pins in the cover need to be removed and I simply screwed the amp down to the floor pan with two screws and then resealed them (for Mini boating of course) before reinstalling the cover. 12 volt power was run from the battery through the firewall near the steering column and then under the door trim without removing it. The ground runs parallel to this line where it skirts the amp box and is bolted to the chassis. I also used the ground from the original amp. Signal wires were run adjacent to the center console, to keep them far from the amp power line, after removing the front portion of the (shift) console and central down tubes. Everything was tested with the passenger seat out of the car but plugged into the cars sensor system; just lay the seat on it’s back and carefully feed the wires through the door jam.

The final configuration uses the HK front set of speakers with a crossover which then connects to the amp while the rear sets are connected in series and then connected to the amp directly, no crossover seems to be required. One could use a low pass filter on the rear set I suppose but as far as I know high frequencies won’t damage a woofer where as low frequencies will damage a tweeter, guaranteed.

For HK amp connections I used the data from GBMini at:http://www.gbmini.net/downloads/HKconnections.pdf

Results:
Results are good. The sound is great and at the moment I have the levels on the amp set to their lowest value for both the front and rear. The bass boost is up a little though. As far as I can tell there is no distortion and the music sounds as good as it ever did and I finally have the HU that I want. There is one difference I can detect though and it’s worth noting. I’ve played with the balance and fade using music as well as the Bink audio test and I can not recreate the sound balance that you experience with the HK “Driver” setting. After some experimentation I now know what the HK amp is doing with this setting. The HK amp has electronic crossovers and sends current to the 8 speakers without “wasting” power in a crossover. This means that you can make the amp smaller, use less power etc. This type of amp has another benefit that is a royal pain to get with a “normal” amp, namely you can send a DIFFERENT amount of current to each speaker.

In “Driver” mode I suspect that the HK amp is sending out power roughly as follows: Driver side front and rear approximately equal volume, passenger side tweet up, passenger side mid approximately equal/up, passenger rear speakers down. Yes, that’s correct the rear passenger side is attenuated. Turns out that speaker has a direct line of sight to the ears (more so than the one right behind you!) so if you adjust the balance to get the highs from the tweeter to come over from the front tweet then you notice the lopsided mid/lows coming from the passenger side rear. Gotta love that guy Bink for his nice test CD! So in a nutshell “Driver” mode uses a custom amount of power to each of the 8 speakers that’s probably been fine tuned using more than just fade/balance. It’s probably possible to recreate this effect but I’m not going to tackle that just yet.

PS, don't forget to remove your CD from the original HU before removing it--or else you'll have to fish a CANbus wire to get the thing to eject it!

PPS:
Since the HU becomes a “conventional” HU when it is not connected to the HK amplifier it is possible, using the pin outs from GBMini, to connect the HU directly to rear speakers using the following strategy. Connect the rear speakers in series as described above using a jumper wire between the appropriate pins. Now connect the left rear speaker pair to the left radio output (pins 30 and 38) being sure to get your polarity correct! Do a similar set up for the right side. I haven’t done this with the Mini HU but I have done it with my new HU (before I got the amp) to test the speaker/crossover arrangement. You won’t get much sound out of the speakers but you’ll get some. You can do the same thing for the fronts if you use a crossover and it might work with just the front midrange alone.

Last step: sell your amp, but the HU is barely worth shipping costs.

 

* After posting the above description I realized I could have been more verbose, not everyone has spent hours piecing together all the info. If you have a blown amp you have 4 options:
1) Keep the head unit and all of “its” functions by buying a used (up to $400) or new ($1000) HK amp. Of course you retain the HK speakers. This is the easiest and will take less than 1 hour.

2) Keep the HU and lose many of its functions by buying a 3rd party amp that has speaker level inputs (the Sony above has speaker level and audio signal level inputs). NOTE, the Mini HU is a 2 channel HU, left front and right front ONLY. But how do you currently get fader you ask? That’s in the amp. Yes, the Mini HU is kind of crappy on it’s own (BTW, it’s made by Alpine or so the tag on the bottom says). The HK amp takes the data from the HU and takes care of fader and balance. So the HK amp is a signal processor, electronic crossover as well as an amplifier—it’s pretty sophisticated so it’s no wonder it should cost more than an off the shelf amp.

Long aside, so: take the pin connecting info from the Hkconections PDF and connect the right speaker outputs from the radio to the right side speaker level input of the amp. I’m guessing that you can simply combine the front and rear channels but you won’t have any fader control—double check with the amp manufacturer about combining the inputs. On fader; you might not really need it since you can adjust it on the amp before you cover it all up. Mine seems good in the center. If you are keeping the HK speakers as I did complete the install by installing a crossover for the front channel and connect the rear voice coils in series as detailed above. You now have a new amp that probably ends up costing you as much as a used HK amp but takes longer to install. And now you don’t have active fader control. Personally I would not go with this option, spending decent money on a real HK amp (option 1) is NOT a bad investment if you like your current system and don’t want a new HU or lots of work. It may even be worth the $1000 they charge for a new amp.

3) Lose the HU and the HK amp but keep the HK speakers. That’s what I described in the above post. The stock HU is rather crappy and I dislike having any car manufacturer force me to use their radio, nav etc. The Mini HU is a 2 channel HU and is only worth anything because it has a decent signal processing amp connected to it. The amp has more brains than the HU. Also, if you want MP3 player input, Bluetooth etc. on the HU then you might as well replace the HU as well. Clearly this option takes a lot longer than option 1 (you’re not going with option 2 at this point right?). This install took me probably about 8 hours, after piecing together all the data.

4) Replace everything, amp, HU and speakers. You’re on your own. It’s identical to option 3 but going to require taking the doors apart as well as the rear panels. Lotta work. Get a free weekend a buddy and lots of pizza and beer. The Crutchfield install instructions (as well as the web) will be very helpful here.

 

Below is the diagram of an amp and head unit (HU) replacement that I completed in my R52. I've also made the same diagram but for the connections when keeping the stock Mini HU. Lastly is a diagram for how to get sound with crossovers only using only the stock Mini HU and the front speakers--no crossovers if you use the rear speakers. Sound without an amp will be suboptimal. I did test the "no amp" configuration with front crossovers using my new HU before installing the amp and yes it does work, just not great. This was done to test the crossover's crossover frequency. Anyone please feel free to chime in if you notice any errors. Many thanks to the previous posters for sharing all the information that made this possible.

Matt

 

Thank-you!!

This little gem of a tip got me some passable tunes for the time being!!

 

I just wanted to add some more info to this as i'm sure there are still R53 owners out there struggling with a dead HK amp.

I ended up finding an "open box" deal on an Alpine MRP-F300 locally for approx $50 USD. I grafted it into my 2006 R53 in place of the HK amp using the existing speaker wiring, and am currently driving the OEM HK speakers while I wait for Amazon to deliver a full set of new Alpine speakers to replace the HK ones.

Essentially all I did was carefully remove all of the leads from the HK amp plug, and put the door tweeters and mids on the pair of channels, and the rear mids on another pair of channels. I connected the HU front speaker outputs from the HK plug to the speaker level inputs on the amp, sharing the signal between the front and rear channels (balance left to right works, but fade is to the front). Amp signal was from the white wire in the HK plug. I taped off the HK power, ground (initially; read on) and K-Bus leads. The full compliment of HK speakers are now "speaking". All things considered, the sound is actually pretty decent albeit temporary. Its not perfect, but more than passable with some crossover tweaking on the amp. Frankly, if I hadn't already bought the new Alpine speakers, i'd be hard-pressed to yank the OEM speakers.

Lastly, one other point worth mentioning. Initially I had some horrendous alternator whine even with the HU off. How bad?; I drove a few blocks and then got out and actually pulled the amp fuse. The whining was despite the Amp "+" lead connected directly to the battery positive, the "-" lead connected to the battery negative chassis ground under the trunk cover, and observing the spacing between leads and speaker wires etc. After reading posts here regarding creating a grounding loop when the amp and HU are grounded in different locations, I simply untaped the brown ground wire from the HK amp plug and connected it to the amp ground terminal (along with the larger ground cable to the chassis ground).... instantly solved the whine. Crystal clear now.

Anyway, many thanks to the forum.