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2001 SLK 320 Sport
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Discussion Starter #1
Okay, so I'm replacing the factory radio in my 2001 SLK with a Kenwood unit from Crutchfield. This one, actually:

http://www.crutchfield.com/S-gC1hQeBOMeS/cgi-bin/ProdView.asp?g=300&I=113EZ900&search=Kenwood+VENDORID113&SearchDisplay=Kenwood

I am using the directions from Paul Lomba from www.slk32.com and have a few questions.

1. Will this radio work in my SLK?

2. I know the SLK does not have a front/rear fader so the left/right rear wires won't be used, but the car has 6 speakers total. Will simply connecting the left/right front wires to this unit acutally use all of the 6 speakers? Does the BOSE Amp split the sound accordingly?

Let me know what 'chall think!

Todd
 

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1999 SLK230 2009 E350
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The head unit will work. The install will be much easier if you use VW wiring harness adapter for your radio. Mechanically it will fit the SLK harness although the wire assignments are different between VW and Mercedes so just make sure you compensate for that.
 

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1999 SLK 230
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You are correct in that the Bose amp accepts only left and right inputs and it will correctly output to the 6 speakers. The proper way to interface to the Bose system is via an adapter such as this one: http://www.cardomain.com/item/PERSVEN2

When you pull the factory head unit you will see what look likes a speaker connector, with two pair of wires leading from it. These are not however speaker wires, they are differential Left and Right channel signals to the Bose amp. The factory Bose amp does not use RCA-type connectors or shielded cables as do most aftermarket systems.

You may be tempted to connect the speaker outputs of your head unit to these Bose amp inputs. This will work (you will get sound) but I don’t recommend it for several reasons. The volume control will be oversensitive. The reason is because of a signal amplitude mismatch. The Kenwood unit is rated about like most aftermarket decks: 22W into 4 ohms. That works out to a signal amplitude of over 9 volts at maximum volume. The Bose amp can take only about 4 volts maximum. So, if you connect this way, you can easily overdrive the Bose amp. Also, since you’re not loading the aftermarket deck anywhere near its rated load, you may get distortion.

If instead of connecting the speaker outputs you use the Kenwood deck’s preamp outputs, you will likely have the opposite problem. Note from the specs that the Kenwood preamp output voltage is 2 volts. The Bose will want to see about 4 volts for maximum volume. So, once again, this will work, but you will not get all the volume out of the system as you would with the stock head unit. Also, you will be connecting single-ended Kenwood outputs to differential Bose inputs.

I agree with the suggestion to use a VW connector.
 

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2003 SLK32 AMG Designo
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Ah - that explains the mystery! The Nokia hands-free car kit installed in my European-spec SLK320 worked perfectly, and also when the radio was off. The same Nokia hands-free car kit in my Bose-equipped SLK32 AMG was a devil to sort out and initially the volume was deafening. The installer eventually sorted that, but there is a lot more interference from various sources within the car when I'm using the hands-free, presumably due to the non-shielded nature of the Bose cables? Also, the hands-free speakers don't work with the radio off....[:(!]
 

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2001 SLK 320 Sport
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Discussion Starter #5
DickB - 1/4/2006 10:37 PM

You are correct in that the Bose amp accepts only left and right inputs and it will correctly output to the 6 speakers. The proper way to interface to the Bose system is via an adapter such as this one: http://www.cardomain.com/item/PERSVEN2

I agree with the suggestion to use a VW connector.
Thanks for this GREAT advice!!

Question about the adapter from cardomain . . . how does it interface with the VW connector? Also, would it connect to the left/right front speaker leads on the Kenwood or on the line outs?

Thanks for any help you can provide!

Todd
 

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nickwilcock - 1/5/2006 3:56 AM
The installer eventually sorted that, but there is a lot more interference from various sources within the car when I'm using the hands-free, presumably due to the non-shielded nature of the Bose cables?
Yes, probably.

Actually, if done properly, the non-shielded differential lines are less sensitive to electrical noise, which is likely why Mercedes went this route. There are two reasons. First, the higher voltage (4 vs. 2) provides more headroom over the noise. Second, the signal is transmitted as a difference, + on one line and - on the other. Induced electrical noise typically gets injected onto both the + and – wires (which are often twisted pair) and gets cancelled out.

If your installer simply connected RCA outs to the differential pair, he in effect grounded one of the signal pair, so injected noise does not get cancelled.
 

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Question about the adapter from cardomain . . . how does it interface with the VW connector?
You match up the pigtail out of the cardomain adapter to the pigtail into the VW connector – 4 wires spliced from one to the other – then just plug it in. Easier to picture than describe. Look up Scosche VW01 connector and compare with the cardomain picture – I think it will make sense.

Also, would it connect to the left/right front speaker leads on the Kenwood or on the line outs?
Either, but I suspect you might need to use the speaker outputs and adjust the cardomain attenuator to match the 4 volt maximum signal into the Bose.

Just to be clear, I have not actually used the cardomain adapter, so I can’t speak from direct experience.
 

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I used a similar product compared to cardomain. http://www.buy.com/retail/product.asp?sku=90119273&loc=111&sp=1
It seems to be OOS now but it was cheaper than cardomain. I was running my head unit with the Bose amp connected to the speaker wires on the harness. It works fine, but can damage the bose amp. I got irritated with the sensitivity of the volume so I got the adapter. (I had to listen to music on volume 2-3) My unit also has 2V preouts. It works when plugged in there (volume was normal) but there was a loud popping sound when changing stations or changing tracks on the CD. This might have been fixed by using a ground loop, but using the adapter was much easier.
Since the bose system is 2-channel, only the fronts were used. the VW harness made everything really easy, but don't forget that you also need an antenna adapter.

--Mike
 

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upstate engineer - 1/4/2006 6:53 PM

The head unit will work. The install will be much easier if you use VW wiring harness adapter for your radio. Mechanically it will fit the SLK harness although the wire assignments are different between VW and Mercedes so just make sure you compensate for that.
The wire assignment was the same on my install with the exception of the Ignition and Constants wires were switched. But double check it just to be sure.

--Mike
 

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2001 SLK 320 Sport
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Discussion Starter #10
toddwess - 1/4/2006 7:44 PM

I am using the directions from Paul Lomba from www.slk32.com and have a few questions.

Todd
Looking at the directions I have a question.

The Blue wire with the white stripe that is identified as "Amp turn on lead" . . . What does this get connected to on a new Head Unit?

Thanks!
 

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Discussion Starter #11
DickB - 1/4/2006 10:37 PM

You are correct in that the Bose amp accepts only left and right inputs and it will correctly output to the 6 speakers. The proper way to interface to the Bose system is via an adapter such as this one: http://www.cardomain.com/item/PERSVEN2

When you pull the factory head unit you will see what look likes a speaker connector, with two pair of wires leading from it. These are not however speaker wires, they are differential Left and Right channel signals to the Bose amp. The factory Bose amp does not use RCA-type connectors or shielded cables as do most aftermarket systems.

You may be tempted to connect the speaker outputs of your head unit to these Bose amp inputs. This will work (you will get sound) but I don’t recommend it for several reasons. The volume control will be oversensitive. The reason is because of a signal amplitude mismatch. The Kenwood unit is rated about like most aftermarket decks: 22W into 4 ohms. That works out to a signal amplitude of over 9 volts at maximum volume. The Bose amp can take only about 4 volts maximum. So, if you connect this way, you can easily overdrive the Bose amp. Also, since you’re not loading the aftermarket deck anywhere near its rated load, you may get distortion.

If instead of connecting the speaker outputs you use the Kenwood deck’s preamp outputs, you will likely have the opposite problem. Note from the specs that the Kenwood preamp output voltage is 2 volts. The Bose will want to see about 4 volts for maximum volume. So, once again, this will work, but you will not get all the volume out of the system as you would with the stock head unit. Also, you will be connecting single-ended Kenwood outputs to differential Bose inputs.

I agree with the suggestion to use a VW connector.
FYI - I bought and used the device you recommended in your post, and it made all the difference! Thanks for taking the time to help me with this issue. Now I have a radio that works just like the original! Thanks, Friend!!!

Todd
 

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This wire turns on the amp when 12 volts is applied to it. Almost all newer head units have an output wire labelled "Turn On" or "Power Control". There is also usually a "Power Antenna" lead, which will work too, but may poewr down if the head unit is not in Radio mode. You can test this if this is the only lead available (as is the case on older head units).
 

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'01 Mercedes SLK230 | '01 BMW R1100S
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If instead of connecting the speaker outputs you use the Kenwood deck’s preamp outputs, you will likely have the opposite problem. Note from the specs that the Kenwood preamp output voltage is 2 volts. The Bose will want to see about 4 volts for maximum volume.
Looking at this unit, Alpine CDA-9885 CD receiver with MP3/WMA/AAC playback at Crutchfield.com
it says in the specs "three sets of 4-volt preamp outputs (subwoofer output has bass level control)". This is exactly what the Bose wants (in addition to the adapter), correct?
 
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