Speakers, Ohms, amplifiers ITT!!!! Please help me!

[aflicted]

I have done extensive searching on multiple Benz forums too help me with my impasse. The stock amp in my bose system is wet the bed. (oh yeah it is a 98 C280 so no optical) The speakers are in great shape, I looked at them and they all sound great for my needs. I replaced the HU for an aftermarket so I could connect my sub with RCA, and get High/low filters etc.... I was thinking about wiring in some 2 Ohm resisters to bring the stock 2 Ohm impedance up. After digging around, I noticed that Best Buy has a 4 channel alpine amp that does 50w x 4 @ 2 Ohm for 83 bucks on clearance. This seems like a no-brainer really if my understanding of the system is correct. Are the fronts really 2 Ohm? I have seen conflicting data on that point. I know I can wire the rear doors/decklid speakers in parallel for a 4 Ohm load, and the amp will hand different loads for front and rear. Are the front speakers 2 or 1 Ohm? The crossover doesn't appear to be in the stock amp so I'm not worried about signaling or power, and they will never see the 50w the amp puts out. (I just don't jack my stereo like that) The local Fry's only has resisters up to 25w rated, but I picked up some 2 ohm to check my original no amp theory, and some 1 ohm in case the fronts are truly 1 ohm. I will order some 50w later if I decide to put the amp in. I am about 3 hours from my house right now, and w/o a multimeter to test the line impedance myself. (I will do this throughout my tinkering to insure stability though) Is there anything I missed? Any solid numbers on speaker impedance? I haven't had music in 6 months and is killing me! PLEASE HELP!

[benztec]

my friend...impedance and resistance are 2 different things. you cannot wire in resistors to change impedance. basically, impedance is when a circuit has resistance and reactance (a moving coil) involved in the equation. an 8ohm speaker is not always 8 ohms throughout its travel and different power levels. just replace all the components in the system. most of the older factory stuff is garbage anywway. you would probably overheat any resistor you would put in there anyway.

[aflicted]

My friend I fail to see where your logic flows from. Impedance is a measure of resistance. If you would like to dispute this simple foundation I implore you to divulge your earth shattering revelation for argument. I have discussed this ideal with multiple electrical engineers. I can vaguely decipher your discernment b/w the coil motion, but it is only in relevance to the amount of current shown the speaker. The factory stuff you can assume as garbage, but that is a purely subjective point, and up for endless debate. If the PE stamping engineers I have been discussing this with are wrong please divulge your revolutionizing idea so that the rest of us can enter the age of enlightenment. I'm sorry if this is harsh, but your first two sentences just seem... well, wrong. Thus your whole foundation of revelation to this idea is... crap

[benztec]

actually. i am an engineer. open a 1st semester electronics text before you go any further. impedance is not a measurement of resistance. trying to sound intelligent with your sarcastic reply just makes you look arrogant. but i see that a lot on these forums. so go find these "engineers" and actually listen when they explain impedance. its not resistance. look up what happens to the power in the circuit when you start wiring in resistors. any guesses? all of benz's factory sound systems were never that good until the current MOST/COMAND configurations of current models. on a 202 body car that is 10yrs old you think its logical to try and save part of a system. these setups usually result in subpar performance due to cheap speakers. No highs, no lows it must be Bose. write it down.

[adamsry]

Well the front 4 1/4 driver is 1.2 Ohm and the Tweet in the dash is 8, the drivers are wired where the present a 6 ohm load to the amp but here is the tricky part the bose factory amp uses a active eq that strips the base info from the L and R channels and then plays it on the rear deck subs in a blended mono system.The crossover is a variable one that actively adjusts based on volume and material being played. I believe this crossover is roughly 16,000 Khz to about 500 Hz

The rear door Twiddler thingies i'm unsure of the impedance but i suspect that they are 6 or 4 ohms. I believe this active crossover is roughly 750 Khz to about 200

The deck subs are 2 ohms i believe and they are on a weird amp switching and phasing system like every other cycle they are mono and the alternate to stereo this is done i presume to improve amp efficiency but still provide left to right base definition.

The rear subs have about a 130hz crossover nothing mid really comes through.

The tweets use a nokia driver "hummm.....?? " I thought it was a bose system ?? " dash tweets" and they have a simple inline capacitor that strips the bass info.

I will tell you this i have 2 Benz one that did not have bose and one that had a broken bose system i was able to retro a bose system in my 2000 c230 and repair the one in my 94. The system has been optimized to our w202 interior and presently there are no really satisfactory products that i have seen that dont require excessive butchering of your doors, or speaker mounts. Non bose speakers sound like crapola in the 2 L tuned ports.

If the amp is working correctly the system sounds extremely well the base is not ghetto and that suits my needs, maybe yours. One thing you have to watch out for is that if your amp has been popping screeching well you probably also have driver damage.

My rear deck subs did this fortunately one was spared the other magnet got so hot that it dam near burned my hand when i removed it ( Some reports on bose driver burn they have been known to ignite from this heat i mention)

I hear many people in her rave about there systems but i'm a stock kinda guy and thus far i have not heard that impresses me to the extent of replacing it. Most systems are pure base pore imaging and muddy midrange.

My recommendation is that you send your amp to bose to have them refurbish it which they will do for under 200 or find a junk yard and yank one for your self and a friend. I got lucky one yard here gave me the complete system for 60 buck i have a couple spares, the other yard sold me the amp for 30.

=)

My 10 cents worth.

[1995c280]

Radio - 15x4 watts, 6 Ohms

Front Tweeters - 8 Ohms, 9,000-20,000 Hz Frequency, Diameter 26mm or 1 inch

Front Door Speakers - 1 Ohm, 85-9,000 Hz Frequency, Diameter 114mm or 4.5 inches

Rear Doors Speakers - 2 Ohms, 180-15,000 Hz Frequency, Diameter 89mm or 3.5 inches

Rear Deck Speakers - 2 Ohms, 35-200 Hz Frequency, Diameter 167mm or 6.5 inches

Amplifier - 40x3 watts & 20x2 watts

[aflicted]

benztec, you actually got the drunken reply of said engineers. I apologize for the offensiveness, it detracts from the point of the thread.

Back on topic:

The speaker information is interesting. I thought the front components were split after the amp. The wiring diagram I found shows 4 input channels and six output channels (two of which being the rear deck speakers) This seemed to reaffirm my impression that they were split after the amp.

I actually just found a post on MBworld.org this morning while doing some more reading.

removed bose, kept speakers (http://forums.mbworld.org/forums/showthread.php?t=65833&highlight=replace+bose+amp)

There is a link to write up in the OP

Also I just got back from talking to the installers at Fry's and Best Buy who said they have put an aftermarket amp on the bose system with no problems. I bought the amp since I have 30 days to return it if I can't use it.

Could I add passive crossovers after the amplifier? How would I do that if the front door channels only have one set of wires for each?

[expo5.0]

many regular aftermarket amps will run the bose speakers resistances no problem- i don't know where this idea comes from that they won't (but it sure is all over the net)

a resistor inline will not have the desired affect- unless that desired affect is HEAT

[aflicted]

Originally posted by expo5.0
many regular aftermarket amps will run the bose speakers resistances no problem- i don't know where this idea comes from that they won't (but it sure is all over the net)

From everything I read, I got the impression that an aftermarket amplifier would run them no problem. (It does seem vague on that point though) I have a new alpine amp to install, but after reading a few of the posts ITT I have a few concerns. How will I manage the routing of the frequencies to the speakers? If the stock Bose amp had the crossovers built in, how is it directing the signal to the tweeter and driver over the same output line?

1995c280 listed the frequency handling of the speakers, and since I'm putting a sub in I will just forgo the rear deck speakers. I'm really only concerned with mid-range and high frequencies from the Bose speakers.

[benzonline]

What happens if you add a pair of 2ohm speakers to a 4ohm system? Somebody I know added a pair of Bose rear deck 2ohm speakers to their non bose 4ohm W202 system and it worked fine! Perhaps because the impedence of the rest of the system balances it out at the head unit? I dont know

[aflicted]

I think it depends on how he wired them into the system. If he added them to the rear channels wired in series (say the rear door @ 4 Ohm and then the 2 Ohm) it would be a 6 Ohm load seen by the receiver. This would be fine as most receivers will handle a 4 - 8 Ohm load. If he replaced the speakers with the 2 Ohm so that it was just a 2 Ohm load on that channel then it is my understanding that it will be damaging to the amplifier in the receiver. Thats what I'm trying to avoid with my system. The aftermarket receiver won't play well with the 2 Ohm Bose setup, but hopefully my 4 channel amp will.

[expo5.0]

yeah- the key is that not many aftermarket hu's internal amps are capable of not overheating/not running on the lower impedence of the bose stuff.

However, most aftermarket (or even stock premium) external amps are capable of playing a quite wide range of impedences (but always check first)

-drew

[adamsry]

http://img244.imageshack.us/img244/8663/78134376zj0.gif


1 Circuit 30, F4-16
2 Ground (W6)
3 Right rear speaker (H4/8) (-)
4 Left rear speaker (H4/7) (-)
5 Right rear door speaker (H4/4) (-)
6 Left rear door speaker (H4/3) (-)
7 Right front door speaker group (H4/2) (-)
8 Left front door speaker group (H411) (-)
9 Right NF signal (+) from A213
10 Circuit 30, F4-16
11 Ground (W6)
12 Right rear speaker (H4/8) (+)
13 Left rear speaker (H4/7) (+)
14 Right rear door speaker (H4/4) (-)
15 Left rear door speaker (H4/3) (+)
16 Right front door speaker group (H4/2) (+)
17 Left front door speaker group (H4/1) (+)
18 Left NF signal (-) from A2/3
19 Control voltage from A2/3
20 Fader switch (R26) (-)
21 Fader switch (R26) (+)
22 Fader switch (R26)
23 -
24 Right NF signal (-) from A2/3
25 Center fill tweeter speaker (H4/11) (-)
26 Center fill tweeter speaker (H4/11) (+)
27 Left NF signal (+) from A2/3

[adamsry]

http://img252.imageshack.us/img252/7844/84933076yh5.gif

[adamsry]

http://img242.imageshack.us/img242/1443/128904011go9.gif http://img242.imageshack.us/img242/3160/128904009bv7.gif
http://img242.imageshack.us/img242/9532/128904008ka5.gif

These are the electrical wiring diagrams for analog Bose no optical amp to speakers which should be applicable for what your doing.

[adamsry]

The tweeter is a 8 Ohm Nokia that sits on the dash. The Bose ( HVC Helical Voice Coil ) Driver " Speaker in the door kick panels is 1.2 Ohm " They are wired in series and present a 6 Ohm load on the amp. The amp used in the 202's also is also similar in design to the one used in the CLK and SLK vehicles the primary difference is a couple of resistors are changed in the amp and viola you have a center channel speaker. It is theoretically possible to use a SLK/CLK amp in a 202.

[benzonline]

Bose writes about HVC Driver:

The Bose 4.5" HVC driver was conceived and designed to be utilized in actively equalized loudspeaker arrays with two design goals in mind. The first goal was to create loudspeakers that did not employ cross-over networks knowing that cross-overs can cause spectral anomalies in the vocal range. Utilizing an array of full-range drivers ensures a smooth frequency response over the entire operating range of the loudspeaker in which they are employed. Secondly, a 4.5 inch driver was an optimal size because a driver of that size can reproduce the desired frequencies with active equalization, all while allowing the enclosures to remain compact.

The voice coil of the HVC driver (helical voice coil driver) is made of aluminum edge-wound, flat wire as opposed to normal round wire. This allows more metal on the bobbin and in the gap to create a more efficient motor structure. The voice coil is sealed in a resin that actually hardens when heated. A plastic basket ensures all gauss is used only to move the voice-coil. The voice coil and bobbin are made of the same material ensuring similar heating characteristics.

With staggering peak power handling, and arduous quality testing during manufacturing, the Bose 4.5 HVC driver has the lowest published failure rate of any driver - less than 0.1% failure rate.

[aflicted]

The first part of that is really interesting. How does the frequency get stripped and actively passed to the driver when the tweeter and midrange are on the same output channel from the amp? The diagram provided (THANK YOU!) ITT shows they split along the way, but doesn't list if there is a crossover on that line.

The rest of that seems fitting with what I saw when I pulled the driver and its enclosure out. All of it seemed very robust, right down to the surround.

[expo5.0]

i'm sure they use simple 6db crossovers inline

-drew

[benzonline]

That description doesnt apply to the W202 or automotive in general...just mostly to the HVC driver which is used in literally all their products. If anyone knows the Bose 901 speaker it houses, 9 of these drivers each speaker...total of 18.

My parents have them in the living room and they move air like CRAZY!

Sorry, im just a audio/Bose freak.

http://img205.imageshack.us/img205/3208/hvcthulinnvf3.jpg

[aflicted]

My old man is a Bose freak too. He has their stuff all over the house, and a pair of their noise canceling headphones for when he travels (often). I am not such a huge fan of them, but I do like their in-ear headphones. I have a pair for my Ipod while I'm on campus.

The image you put up actually looks identical to the speaker I pulled out of my door. The cone was gray not blue though.

Expo : I was thinking they had to have some type of crossover inline. I guess I'll wire in this amplifier this evening when I get home from class and see what happens. I hope it sounds good, and doesn't destroy anything.

[adamsry]

the tweeter has a tiny capacitor that filters out base frequency it is a cost cutting measure a inline cap can filter bass it is a cheep real cheep crossover actually you can see it on the back of your tweet looks like the size of an eraser on a pencil.

[adamsry]

The automotive bose driver has a fabric canvas surround to prevent foam rot also the paper is treated with i believe some kinda asphalt/rubber material to make it resistant to moisture but as time progresses the organic material degrades and the driver fades from black to more of a tan color. You can steel the drivers from Audis they are the same impedance and material combo.

The particular driver in our cars are more rigid and are centered around a very tight suspension in the speaker coil so the frequency response is VERRRY midrange.

I suspect the driver can comfortably drive 200hz to about 3800khz and the tweet picks up 4000khz to 16000khz. When our stereo was developed bose at that time did not offer car tweeters now the newer E Classes 97 up bose did so that's why they actually have genuine bose tweets opposed to the w202 which has the Nokia tweets.

Think of this bose driver as the most versatile for example 2 of them are used for the Bass Box in audi's , in a bandpass enclosure. The outer surround instead of being canvas is rubber to provide grater movement and improved bass handling.

The really big wave radio the one the size of a brief case uses one of these drivers to provide all the bass sound the rest is enclosed in transmission line to push certain frequency's.

.....

[benzonline]

Last summer I replaced the front HVC drivers with the newest silicone version as something happened to one of the original ones. Sound is unchanged but the driver is much more durable.

http://img99.imageshack.us/img99/6981/1605071738xw0.jpg

http://img214.imageshack.us/img214/425/1605071737he9.jpg

http://img401.imageshack.us/img401/7786/1605071818ja4.jpg

Original:
http://img293.imageshack.us/img293/5846/bosew202hvcpe2.png

By the way, any info on the rear woofers? How many HZ do those reach down to?

[aflicted]

Are those rubber surrounds on them? They look good. I'm hoping that these will hold up a while, but at 10 years old who knows.

I won't be overdriving them, this amp is modestly powered. I have the low frequencies covered so I really just need decent mid and high end. How much were the new ones? If you don't mind my asking.

[benzonline]

The new ones were about $45-50 each speaker, from Bose. They arent rubber, but some silicone type material all around.

If yours arent damaged leave them...wont make a difference, these can outlast the whole car.

[aflicted]

I'll leave mine till they go south, and I suppose I'll find out after I hook this amp up tomorrow. That is the firm deadline for it, and I'll post my final setup and results tomorrow evening. If I do kill them though it is good to know there is an attractive alternative out there. Though powering them will once again become a concern.

I suppose if I somehow kill the speakers, but not them amp then I'll just cough up the dough for new speakers and custom made adapters for them to mount to. I'd rather not spend the cash on it. The car has 175k miles and I'll likely add a newer E class to my driveway to replace it when I get out of Uni this semester. I plan on always having this car though as it represents my first love for the "three stars" Plus everything about the car is solid as a rock (Bose amp not withstanding) so I might even drive it for a few more years before adding another one to the herd.

[c55m8o]

awesome info already; nothing worth adding from me.

One thing I can do -- now I'm not sure when I'll be able to -- is to use my AudioToolbox to measure the impedance at the rear connector across the frequency spectrum reflected back to the amp. This way we'll all know exactly what the amp sees through-out the frequency range. Can't get to it this weekend; hope next.

[aflicted]

Originally posted by c55m8o

One thing I can do -- now I'm not sure when I'll be able to -- is to use my AudioToolbox to measure the impedance at the rear connector across the frequency spectrum reflected back to the amp. This way we'll all know exactly what the amp sees through-out the frequency range.

This would be awesome. I have been trying to find this out for quite awhile but lack the tools to do it.

It is supposed to snow here this evening or tonight sometime. I may or may not put that amp in. Just depends on how much daylight I have left after class and how cold it gets.

Edit: Well I'm in the middle of installing the amp, but my bose harness is not quite what adamsry posted earlier. It actually fit this description. I used Adamsry's speaker labeling diagram and paired it up with the schematic to determine the coloring for each speaker. ( http://www.club202.com/forums/editpost.php?s=&action=editpost&postid=144027 )
Also I found this good ouline for routing the source wires to the head unit ( http://www.club202.com/forums/showthread.php?s=&threadid=6838&highlight=amp+install )