ohm change and xovers

rptrsn2 · #1 06-13-2011, 10:32 PM

I have 2 old 215+horn cabs that are 8ohm each, I have aquired 4 15" black widows and want to put them into these cabs making then 4ohm cabs. What will be the effect on the Xover and horn in these cabs. I want to keep the horn as these will prolly be used for pa mains. Thanks.

DukeLeJeune · #2 06-13-2011, 11:50 PM

Without knowing a fair amount about your crossover, your old woofers, and your black widows, I can't say precisely what frequency response problems you will have. But I can say with confidence that if the crossover works well with the woofers that are in the cab now, it will not work well when you substitute different woofers with half the total impedance of the originals.

If you care at all about sound quality, I suggest you find another solution.

rpsands · #3 06-14-2011, 01:06 AM

If you know the characteristics of your horn there are some passable off the shelf crossovers available from a variety of sources.

Peavey might even sell you a couple of replacement xovers for their SP4 cabs if you call up and ask nicely. The low pass side is likely going to be suitable for the woofer at least.

No clue on the high pass side unfortunately. Peavey would be the ones to ask how to make those cabs work.

lbwdog · #4 06-14-2011, 05:56 AM

The "no cost" solution would be to first hook 'em up without the HF horns in the circuit. You might be satisfied with the results, unless you absolutely have to have tweeters.

If tweeters are a must have, then you would definitely need a 4 Ohm crossover for proper operation of the woofers. If crossed over high enough, the tweeters might perform good enough depending on your preferences.

(this is just my barely educated opinion. Duke, R.P., correct me if I'm way off.)

billfitzmaurice · #5 06-14-2011, 06:16 AM

Quote:

Originally Posted by lbwdog

The "no cost" solution would be to first hook 'em up without the HF horns in the circuit. You might be satisfied with the results, unless you absolutely have to have tweeters.

I believe that "these will prolly be used for pa mains" answers that question.
But on that point 2x15/horn cabs are probably the worst choice for PA cabs. The OP should reconsider that usage.

lbwdog · #6 06-14-2011, 08:52 AM

Quote:

Originally Posted by billfitzmaurice

I believe that "these will prolly be used for pa mains" answers that question.
But on that point 2x15/horn cabs are probably the worst choice for PA cabs. The OP should reconsider that usage.

OH S***! Didn't even read that! I'm thinking bass cabs.
Agreed on all counts in that case....

rptrsn2 · #7 06-14-2011, 09:32 PM

Quote:

Originally Posted by billfitzmaurice

I believe that "these will prolly be used for pa mains" answers that question.
But on that point 2x15/horn cabs are probably the worst choice for PA cabs. The OP should reconsider that usage.

Really, these are two old 1970 Kustom TnRs and we have people specifically comment on how clear and great they sound. The only reason for changing drivers is to use my amps potential. If lowering to 4ohms not going to work I will get a more powerful amp at 8ohm per channel. I also found out that 2 of the black widows are 12s. We went to look at some lights for sale and in the garage the guy had 2 mb2 and 2 sp2 speakers which i bought for $100 for all 4 together. One sp2 hs a blown horn but figured the drivers alone should be worth the $100

MuzikMan · #8 06-14-2011, 09:46 PM

If you like the way the cabs sound why would you change the speakers? That makes no sense, especially if your reason is to pull a few more watts out of your amps. You won't really notice a difference in volume and there is NO WAY your cabs are going to sound the same, not to mention that you need to change the crossover network. You are barking up the wrong tree my friend.

Guys, I'm going to need a little backup here!

will33 · #9 06-14-2011, 10:00 PM

Quote:

Originally Posted by MuzikMan

If you like the way the cabs sound why would you change the speakers? That makes no sense, especially if your reason is to pull a few more watts out of your amps. You won't really notice a difference in volume and there is NO WAY your cabs are going to sound the same, not to mention that you need to change the crossover network. You are barking up the wrong tree my friend.

Guys, I'm going to need a little backup here!

Good points. Aside from ohms and xovers just throwing different spec drivers in the box will be crapshoot. Might sound worse...might not but it'll damn sure sound different. It sounds good now so if it ain't broke.....

That said if you absolutely must mess with it, start at the crossover and hope it isn't a true 2-way xover. If it's just a HPF for the tweet you can put whatever woofers you want in there without redoing it. If it's a real xover you'll have to redo the lowpass side. Save all the old parts so you can put it back like it was when you figure out the whole mess wasn't worth it.