wiring a center channel in d'appolito

beat · « **on:** 7 Feb 2003, 04:17 am »

another wiring problem, this time I have two 8 ohm woofers and a 4 ohm tweeter. I wired the whole thing in parallel and got 3.7 ohms at the jacks. What I did to boost the resistance was passed the power straight through the first woofer before reaching the crossover (there is no low pass filter in the cross). So everything gets power after being passed through the first woofer..Is this ok? It sounds fine I guess but is not as loud as before. On the bonus side the resistance is now up to close to 12 ohms. Will this arrangement cause fidelity loss?

JohnR · « **Reply #1 on:** 7 Feb 2003, 06:21 am »

Quote from: beat

Will this arrangement cause fidelity loss?

Most likely... why are you doing this?

beat · « **Reply #2 on:** 8 Feb 2003, 04:35 am »

I tried wiring it like that to boost the resistance to make the amp happy. It asks for 6 ohms or more but with the wiring arrangement as I have it it is at 4...two 8 ohm woofers wired in parallel..do you know of another option? Where are you in berkeley john? that is my old stomping grounds..I miss the coffee I'm an old peets head

JohnR · « **Reply #3 on:** 8 Feb 2003, 10:59 am »

I am (quite literally) over the hill! Just off Tilden Park.

It seems rather odd that an amp should insist on 6 ohms or more. Especially since a lot of center channels will be 4 ohms nominal. Well, if it sounds OK, cool, but I think I would be looking for another amp... or more likely I would just run it at 4 ohms and see if it blew up

(not recommending the above, just saying what I would do

)

beat · « **Reply #4 on:** 8 Feb 2003, 05:59 pm »

tilden park...nice. I miss the "blazes" I'd go on with my buddy up there. That was what we'd call a motorcyle ride. So John you think I'd be fine running it at 4 huh? And you think most are that anyway? I'm modeling these after the def tech 2000 which is what the drivers actually are. The website claims they are 4-8 ohms (whatever that means) I don't see how they couldn't just give one value.

JohnR · « **Reply #5 on:** 8 Feb 2003, 11:31 pm »

Um, don't do it because I said so! I take absolutely no responsibility

My advice is to get a better amp

What amp is this anyway? What exactly does it say about the 6 ohm business?

beat · « **Reply #6 on:** 9 Feb 2003, 06:27 pm »

its a new marantz 7300. It just states as most do..right by the speaker jacks, "right, left, center, rear, 6-18 ohms" or something to that effect. I've never given those tags much attention but I've never kicked down 1000.00 for an amp before either.

greve · « **Reply #7 on:** 9 Feb 2003, 07:52 pm »

Quote from: beat

The website claims they are 4-8 ohms (whatever that means) I don't see how they couldn't just give one value.

The resistance/impedance varies with frequency, so a speaker will (should) for example be rated as 3-8 Ohm. Your amp should be fine with a minimum 4 Ohm, but if your speakers are excessively below this value for a large part of the frequency spectrum, you might run into trouble with your amp.

You can't calculate the resulting speaker resistance/impedance curve unless you have the data per drive unit and then it depends on how you wire them up and your x-overs are part of the equation as well.

beat · « **Reply #8 on:** 9 Feb 2003, 08:52 pm »

Greve, thanks for that info, it makes sense. Did you catch first part of my post? Where I mentioned how I ran the wires and got quite a bit more resistance? Will I lose sound quality this way? Do you have a suggestion on how to wire this beast? What other info would one need?

greve · « **Reply #9 on:** 9 Feb 2003, 11:03 pm »

beat, I did read that part as well, but unfortunately my electrical engineering degree only taught me to calculate resistance, nothing about sound quality

Hopefully someone else can help on that matter...

beat · « **Reply #10 on:** 10 Feb 2003, 04:48 pm »

thanks greve, I'll get it figured out. Nice system you have there, when I get mine all set up I'll post some pics.

markC · « **Reply #11 on:** 13 Feb 2003, 06:41 pm »

I do not profess to know a ton about speaker builing, but it would seem to me that running the power straight through the first woofer couldn't help but mess up the sound. With no low pass x-over b4 the woofer,I believe it would be exposed to the full frequency range. If you look at the magnitude vs. frequency chart for most woofers, you will see that most get way out of whack beyond about 2.5khz - 3.5khz.