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Discussion Starter #1
All of my infinity speakers came in today and I'm about ready to tackle them. I've been doing stereo work for 20 years now so don't think it will be a problem. Anyway, I pulled the A-pillars off today to check the ohm's of the factory tweeters since I''ll be replacing those next. The damn things don't read anything on my meter. There's a cap on them to cross them over but even with that I should get something. The wires leading to the tweeter have an ohm load of 2.5 if anyone is interested. My question is this. Infinity offers two different tweeters that I would probably go with. They have a 2 and a 4 ohm version. I'd like to use the 2 ohm Kappa series but don't know if that ohm load even with there supplied crossover may be to low for the factory amp. I reallly don't want the door speakers over powering the factory tweeter because I like the staging right now. I know that everyone has said that with the tweeters in the 6 1/2's in the door's has been bringing the staging down. (Other thread) One option is to not hook them up I guess but I would really like to replace the facory tweeters anyway. Any of you audio gurus have any input???? These are the tweeters I would like to use.

http://www.woofersetc.com/index.cfm?fuseaction=product.display&Product_ID=2937

Shane
 

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You'll be fine running 2 ohms. Tweeters don't require anywhere near the power a sub does to push. You may need some adjustment, but the crossovers should have a jumper/switch for that.
 

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Where is the factory crossover for the front stage? I was thinking of buying a 2 ohm component set from Image Dynamics and using the factory to push it, but I would have to cut into the full range factory signal before this crossover. Only problem is I have no idea where the hell it is...

Let us know how much more efficient the Kappa door speakers are than the factory tweeters. I don't want to use the Kappas and be unsatisfied with the front staging.

On another note (sorry for all teh questions!) do you know how much power the factory Bose amp is capable of at 2 ohms?
 

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Discussion Starter #4
IT looks like the signal coming out of the bose amp to the front doors is going to be crossed over between 100 to 150 hrtz. The signal going to the tweeter is basically just an extension off of the 6 1/2 in the door. It looks like the factory 6 1/2 is going to be around a 2.5 ohm driver and then when adding the tweeter to it with it's capacitor on the tweeter the factory amp is seeing around a 2 ohm load. With the tweeter being crossed over with the capacitor around 3500 hrtz the amp is not seeing much of a load with the tweeter added. Basically what I'm saying is the speaker wire going to the tweeter in the A-pillar is crossed over at 100 hrtz give or take just like the door speaker. I think I'll be ordering the Infinity reference 1011t (4 ohm) tweeters instead just so I don't have to worry about the Bose amps load. It's amazing how much more efficient the Infinity speakers are versus the factory Bose. I still haven't decided if I'll use the tweeter and the crossover for the 6 1/2's in the front doors or just use the woofer input at the speaker and not use the tweeter and crossover at all. Going to listen to it both ways and make a decision. I'll keep everyone posted with my finding.

Shane
 

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Hey Shane,

Can you make a little howto with pics on taking the pillars off and replacing the tweeters?

Cliff
 

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Gentlemen -

To properly measure impedance you need something like:

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=390-802

And this of course isn't the holy grail, just something I could find quickly.

I've done the car stereo thing for longer than I care to admit, as well as built many, many home speaker designs, active and passive, tube or not, bi, tri, and quad amped...I really don't care to admit the miserable failures of line arrays or successes of basement sized folded horn subwoofers. One of my best friends paid for his EE by actually designing drivers for OEM systems...trust me, an ohm meter across the terminals of ANY driver tells you basically nothing.

I know many like to believe (especially in the car audio world) that a simple ohm-meter will tell you the impedance of a driver - but it simply isn't accurate. There isn't enough engineer built into me to tell you why - buy I can tell you that I built a pair of 23 driver (per cabinet) line arrays (15 five inch midbass and 8 ribbon tweeters per side) and tried to create a x-over based on what I THOUGHT were 4 ohm midbass drivers (had the drivers, not the specs). It was a ton of oak, MDF, HDF, router work, soldering, drilling, gluing, sanding and finishing and ultimately - miserable failure. That was 3 years ago. I stuffed them into a corner, sad that I spent so much time on the project (not to mention money). Fast forward 2 years, and my EE friend asks me how the "pipe dream project" is coming. I give him the quick rundown...

He says "...give me one of your midbass driver's, I bet that's causing you the heartache in the (complex) crossover, not the design of the crossover (he designed it based on specs I gave him)..." Turns out those drivers that showed ~4ohm with a simple ohm-meter (and were labelled the same by Partsexpress) were actually 6 ohm drivers! Wire a bunch of those in series/parallel/powerloading configuration and build an x-over based on what you thought the total system impedance was and...well...it sucks!

About 2 months ago I dug them out, set them up, and bi-amped them with a pair of big ass Crown studio amps that I had laying around (don't ask). Ran them through an active crossover, and guess what? They are f'in incredible - awesome - and I'm trying to figure out where to stash them in the house now :D

OK - so serious threadjack - off now.

Shane -

I bet you find you like the Infinity tweeter as well. Possibly skip the entire tweeter circuit (if you can) and wire the components as you normally would from the primary (midbass) Bose amp circuit to the door?

Back to my regularly scheduled program of Fat Tire and Heidelberg news ;)
 

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CadV said:
Hey Shane,

Can you make a little howto with pics on taking the pillars off and replacing the tweeters?

Cliff
Shane and I are tearing apart my car tomorrow....A-pillars, doors, rear, you name it. Everything but the front seats. Extensive sound-deadening session and sub install.
Look for pics soon after our Meet.

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urbanski said:
Shane and I are tearing apart my car tomorrow....A-pillars, doors, rear, you name it. Everything but the front seats. Extensive sound-deadening session and sub install.
Look for pics soon after our Meet.
Awesome thanks
 

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I knew my EE degree would come in handy.

When you measure a speaker with an Ohm meter, it simply reads the resistance of the speaker coil.

Using Ohm's law: R=E/I

Speaker Impedance varies with frequency and the above formula no longer works. I won't bore you with any more formulas other than to mention that the Impedance formula includes frequency.

GT



 

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Any updates on the audio install?
 

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Discussion Starter #16
Urbanski's pretty banged up from the install. Poor guys hands look like they went through a meat grinder. The sound deadening he did caused a few cuts. Everything turned out great though and he'll post pics soon I'm sure. Oh, his car is very fast for N/A. For those on the fence about the UUC, after driving Urb's it will be one of my next mods. I was pretty happy with the factory shifter till I drove his also.

Shane
 

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I have the non Bose tweeters and on the back of mine they were marked 4 Ohm (they're still little paper suckers) anyway I too put in Infinity Reference component speakers with the 1" tweeters in the A-post. There is so much more brightness to the music just running of the stock amp (had to dial back the treble). Just purchased an MTX 4 channel 65W per channel 4 ohm amp, can't wait to see what this does to the system as the stock amp just doesn't haveenough lead in its ass to run those things past about mid volume without falling apart.
 
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