Converting 8 to 4 ohm 3 Way Cab Help

[churchpark]

I currently have this setup:

3 way cab
Two 8" drivers 16 ohms each for = 8 ohms
One 15" woofer 8 ohms

3 way Eminence crossover 400W HIGH MID WOOFER terminals 8 ohms

The cab is presently rating on my ohm reader at 6.7 and I am trying to get it at 4 ohms to take the advantage of my amp head. The amp head is 350W at 8 ohms and 500W at 4 ohms.

Can I make some magic by removing the 15" to the crossover terminal and wire it direct to the input jack to the cab to obtain 4 ohms of closer?

Here is what I am seeing. If stand alone the the two 8 drivers aong with the tweeter connected to the crossover is still a 8 ohm setup, as if it was a stand alone cab. Then say in the same manner daisy chaining it to a 15" 8 ohm cab making 4 ohms. Some what weird thoughts brings me here for help.

[bongomania]

The fact that your meter says 6.7 ohms suggests that the point where you are taking the measurement is only connected to one of the 8 ohm loads, not both. For you to be getting both loads, they would have to either be series (2.67 ohms) or parallel (4 ohms), there's no way to get 8.

Try using the continuity tester function to verify that the terminals you test at are connected to both sets of speakers.

[darius8]

This sounds very familiar... hmm

[B-string]

Sorry no magic to be had. If you want more sound (and power) add a second cab. A second cab will add more sound than just the bump in wattage alone, anyway you slice it.

BTW if you did try your suggestion the 4 ohm load would only happen at the passband of the mid drivers (like 500Hz to 2500Hz).

[B-string]

Originally Posted by bongomania

The fact that your meter says 6.7 ohms suggests that the point where you are taking the measurement is only connected to one of the 8 ohm loads, not both. For you to be getting both loads, they would have to either be series (2.67 ohms) or parallel (4 ohms), there's no way to get 8.

Try using the continuity tester function to verify that the terminals you test at are connected to both sets of speakers.

He is reading DCR through a crossover.

[churchpark]

B-string are your saying that the only change would be the frequency
Of the x-over would change but more power?

[B-string]

The impedance would drop (amp power would increase) only in the frequencies of the mid range drivers (up to the point the woofer can reproduce). So more power in the mids, no more power in the lows (very unbalanced sound output).

[churchpark]

Ok, I'll leave it as is.

[B-string]

Originally Posted by churchpark

Ok, I'll leave it as is.

Best idea Add a second cab, you'll be MUCH happier with the results.

[churchpark]

It's based on a combo setup. I'm a person
That likes to have full measure. It's a Carvin
R1015 Cyclops cab. In its original setup it had the two
tweeters linked with the original crossover using 8
ohms, however the 15 woofer was at 4 ohms. Weird
huh? However the only turn around was the matrix of
the amp head in which they used. It was a dual mono
block with individual power for the lows and the highs.
Carvin R1000 Redline series. I play at church and was in
need of a take away system for when I go visit other
churches.

[billfitzmaurice]

Originally Posted by churchpark

I am trying to get it at 4 ohms to take the advantage of my amp head. The amp head is 350W at 8 ohms and 500W at 4 ohms.

The difference would be inaudible anyway. Leave it alone.

[DogBone]

Originally Posted by B-string

He is reading DCR through a crossover.

Beat me to it.

Originally Posted by churchpark

Ok, I'll leave it as is.

Good call.

The "extra watts" wouldn't make much of a sonic difference anyway, just mostly additional heat.

Often a higher impedence cab can actually sound better and have more percieved "punch" as it puts less of a strain (output current load) on a given amplifier.

IMO, YMMV, etc etc etc.

Anyway, all I'm saying is sometimes less is more.

[churchpark]

Ok thanks!

[churchpark]

Ok thanks, but what about headroom?

[billfitzmaurice]

Originally Posted by churchpark

Ok thanks, but what about headroom?

What about it?

[BurningSkies]

Originally Posted by billfitzmaurice

What about it?

I like headroom. I didn't get any by moving from 350w to 500w though.

I went from 500w to +2400w. Of course, instead of limiting your headroom from your amp at that point, you're limiting from the speaker...which could really bite you in the ass if you're not careful.

[billfitzmaurice]

Originally Posted by BurningSkies

I like headroom. I didn't get any by moving from 350w to 500w though.

I went from 500w to +2400w

+1. If you need more headroom you get it by increasing the amp size by a factor of four or more, or adding a second cab. You don't get it by just lowering the impedance load, as whatever you gain in voltage swing you lose in current capacity.

[churchpark]

Ok, just another inquire. I am have one of those
super bullet tweeters rated 300W at 4-8 ohms attached to
a:
Eminence PXB33K5 PXB3:3K5 3 Way Crossovers Board 400W/500Hz:3.5k​Hz/12dB/8 ohms

2) 50W L-Pads one for tweeter, the other for the 2 8s for mids.

And lets not forget the speaker specs:

2) 8 inch woofer for MIDS linked to make 8 ohms 450W
1) 15 woofer 8 ohm 600W

Should I change the wattage of the L-Pad or in short, "What would be the genuine setup for this system?

[BurningSkies]

More than 50w for the tweeter? No.

Are you talking about variable L-pads? If so, I'm in the camp which says 'use a fixed L-Pad on the mid or none at all'.

[churchpark]

A fixed L-pad?