Weird 2-8" Cab Idea...Opinions Please

GLUGSTER · #1 09-11-2010, 06:38 AM

I own a Crate BT220 bass combo and I'm very happy with it's gain channel. The stock speaker is pretty OK, but I had a really sweet Eminence Basslite 15" laying around, so I replaced the stock speaker and the 24 gauge speaker wire with this speaker and 16 gauge wire. Sounds better, to be certain, but I started to think about the frequency range of this amp, and how the speaker only goes to 2.5kHz, and that's all fine and good...but I always want to push this stuff a little further...

So this amp runs at 4 Ohms, but the manual has listed the use of another 4 Ohm cab will RAISE the overall imp. to 8 Ohm (look it up, it's strange, I know)...so the only acceptable cab has to be 4 Ohm. The wattage drops a but but nothing to crazy. Alright, I got to thinking...The 15" Basslite delivers the low end just fine with distortion channel, but since this amp has no horn (which is a GREAT thing with gain, IMHO), I thought that some smaller speakers might deliver a bit of presence to the mix, and not require to much power to get some air movin'!

Long story short, I decided to possibly make a 2-8" speaker cab as a companion to this nice sounding combo. I can get everything I need for it for just over a Hundo. The only thing I was thinking about getting for it that might spark some controversy is an inline 4 Ohm high pass crossover, it costs around $12 shipped, and it's specs seem to be perfect to cut Frequencies below 600Hz.

The cab design that seems suitable would be a sealed one, probably filled with polyfill. Internal dimensions would be 16"X9"X6"...strangely enough this calculates to 864 cu in. or EXACTLY .5 cu. ft. Each 8" incher wants between .18' to .25, so I think this might work out just fine.

Does anyone have any opinions on this plan? Should I avoid the High Pass Filter/X-over? Is this even a good idea? Should I just avoid this project? Does anyone think it's a GOOD idea? Any constructive tips or critique would be greatly appreciated. Thanks again in advance for any and all responses, I realize this is a huge wall of text and if you've made it this far, I'm proud of you!!!!

Crockettnj · #2 09-11-2010, 06:43 AM

"(look it up, it's strange, I know)"

The external speaker jack is wired in series. From the amplifiers perspective, you could add virtually any compliment of speaker to it since it'll be in series and not lower impedance.

how it will sound or if it'd be worthwhile is another matter.

GLUGSTER · #3 09-11-2010, 06:47 AM

Quote:

Originally Posted by Crockettnj

"(look it up, it's strange, I know)"

The external speaker jack is wired in series. From the amplifiers perspective, you could add virtually any compliment of speaker to it since it'll be in series and not lower impedance.

how it will sound or if it'd be worthwhile is another matter.

"how it will sound or if it'd be worthwhile is another matter."

Yeah, that's why I'm asking you guys your *opinions*. I'm contemplating this, and I think it might be pretty cool, but *maybe* someone has done something like this in the past, and has some idea if it "Sounds great, and was TOTALLY worthwhile!!", or not.

Crockettnj · #4 09-11-2010, 07:03 AM

consider-

your amp is providing full output to a 4 ohm driver. Connecting another cab will reduce power to the existing driver as well reducing available power overall (4 ohm to 8 ohm overall by adding the extension).

If you are looking to just add presence to the mix, I would not leave out a crossover, especially in your situation.

I havent done what you are considering, so I cant speak from experience, but it's also unlikely you need two 8" drivers to accomplish what you are after. A well chosen 5 or 6" driver would cost a similar amount and provide al the mid and high snap you'll likely want to compliment your basslight 15.

Good luck with it, and I'd wait to hear more voices before buying.

IMO dont skip the Xover for this mod unless you are adding another large, capable woofer.

GLUGSTER · #5 09-11-2010, 07:25 AM

Quote:

Originally Posted by Crockettnj

consider-

your amp is providing full output to a 4 ohm driver. Connecting another cab will reduce power to the existing driver as well reducing available power overall (4 ohm to 8 ohm overall by adding the extension).

If you are looking to just add presence to the mix, I would not leave out a crossover, especially in your situation.

I havent done what you are considering, so I cant speak from experience, but it's also unlikely you need two 8" drivers to accomplish what you are after. A well chosen 5 or 6" driver would cost a similar amount and provide al the mid and high snap you'll likely want to compliment your basslight 15.

Good luck with it, and I'd wait to hear more voices before buying.

IMO dont skip the Xover for this mod unless you are adding another large, capable woofer.

Excellent. The reason why I posted this is: A)this project uses PA type of drivers, B) you guys seem like you are very knowledgeable,
C) This is a cab that I will use in a live situation and
D) Many of you guys I have met over the years have made their own cabs at some point....

Stumbo · #6 09-11-2010, 01:47 PM

Seems you could use two 2 ohm inputs at the same time to get the 4ohms.

MNAirHead · #7 09-13-2010, 07:32 AM

I have a designed cab that's 1x12+2x8

Cool setup .. not sure I'd spend the time again to do all this time and expense.

IF you could find a used one, it may be worthy.. if not available, why not just pass?

GLUGSTER · #8 09-13-2010, 11:47 AM

So you say pass...to much time and effort. Yeah, I dn't think anything like this is gonna "come up" seeing as how it's somewhat specialized. anyway, does anyone else have their $0.02 on this thread?

billfitzmaurice · #9 09-13-2010, 12:00 PM

Quote:

Originally Posted by GLUGSTER

So you say pass...to much time and effort. Yeah, I dn't think anything like this is gonna "come up" seeing as how it's somewhat specialized. anyway, does anyone else have their $0.02 on this thread?

Read the fEarful threads.

Petebass · #10 09-13-2010, 12:58 PM

FWIW, if the mid drivers are behind a crossover, they won't affect the nominal impedance anyway. If it was a 4 ohm cab without the mid drivers, it's still a 4 ohm cab after you add the mids, provided of course the crossover is done right.

PunkSweeper · #11 09-13-2010, 07:27 PM

If the extension output puts the cab in series, any cross over you put on the 8's will be on the same circuit as the fifteen. In other words, there will be no bass.

An extremely small internal volume for the 2x8" might work for an acoustic excursion limiter (w/o XO), but that's still pretty far from ideal. That combo isn't worth the trouble anyways.

GLUGSTER · #12 09-14-2010, 03:10 AM

Quote:

Originally Posted by PunkSweeper

If the extension output puts the cab in series, any cross over you put on the 8's will be on the same circuit as the fifteen. In other words, there will be no bass.

An extremely small internal volume for the 2x8" might work for an acoustic excursion limiter (w/o XO), but that's still pretty far from ideal. That combo isn't worth the trouble anyways.

See I really like this combo for what I am doing. Anyhow, thanks for the knowledge about the crossover killing all the bass in both the 8s and the 15"...Are you sure about that? The way I'm visualizing what you are saying is that the X-over would be kinda like a cap connected to a tone pot...Am I picturing this right?

Petebass · #13 09-14-2010, 04:25 PM

Quote:

Originally Posted by PunkSweeper

If the extension output puts the cab in series, any cross over you put on the 8's will be on the same circuit as the fifteen. In other words, there will be no bass.

If it were me, I'd connect the 2x8 (with crossover), directly to the 15" speaker = parallel link. All speakers will work as they should.