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Adding 6" mid-range driver to cab

NicJimBass

NicJimBass

Flossin'? I thought your name was Munson!
Nov 22, 2004
3,990
2,227
46
Lancaster, OH
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#1
I have a pair of Avatar SB112, non-neo version, which have Eminence Delta 12's, as well as a tweeter. I find that the tweeter, for me, is fairly useless. I want to either add a 6" mid driver, making it a 3-way cab, or replace the tweeter with a mid driver, making it a 2-way cab, without the annoying tweeter-ness. After researching a bit, I've come to the understanding that I'll need a new crossover in order to add the mid driver.

Currently, I'm leaning toward the Eminence Alpha 6a and an Eminence PXB2:500 crossover. I've looked at the SPL levels of the 12 and the 6, and they are fairly close, at least on paper. My weak spot is frequency info. I know I love the low-mid boost/cut on GK heads, which they say is centered around 250Hz, so I figure going to 500Hz will allow the 12 to focus on frequencies close to what I like. There is also an 800Hz version of the same crossover, so I'm curious if that might suit me better than the 500Hz version. Sound-wise, I'm looking to have good, clean lows, but enough mids and highs to allow what I'm playing to be audible. I know this is impossible, but I guess I'm looking to get close to a fEarful cab, low end with clarity, but on a budget. Can anyone steer me in the right direction? Thanks! :bassist:
 
#2
i think your 12's are still omnidirectional around 800. if you cross them at 500 the cab will seem to lose some volume because the 6" cannot reproduce the 500-800 as efficiently as the two 12's. i would go with an 800hz crossover. i used to add 500hz to get that jaco flavor/tone. its midrange but it adds punch and i dont think the 6" would cut it. johnny a. staind
 
#3
NicJimBass said:
I have a pair of Avatar SB112, non-neo version, which have Eminence Delta 12's, as well as a tweeter. I find that the tweeter, for me, is fairly useless. I want to either add a 6" mid driver, making it a 3-way cab, or replace the tweeter with a mid driver, making it a 2-way cab, without the annoying tweeter-ness. After researching a bit, I've come to the understanding that I'll need a new crossover in order to add the mid driver.

Currently, I'm leaning toward the Eminence Alpha 6a and an Eminence PXB2:500 crossover. I've looked at the SPL levels of the 12 and the 6, and they are fairly close, at least on paper. My weak spot is frequency info. I know I love the low-mid boost/cut on GK heads, which they say is centered around 250Hz, so I figure going to 500Hz will allow the 12 to focus on frequencies close to what I like. There is also an 800Hz version of the same crossover, so I'm curious if that might suit me better than the 500Hz version. Sound-wise, I'm looking to have good, clean lows, but enough mids and highs to allow what I'm playing to be audible. I know this is impossible, but I guess I'm looking to get close to a fEarful cab, low end with clarity, but on a budget. Can anyone steer me in the right direction? Thanks! :bassist:
Click to expand...

Not much point in adding a mid driver to a cab loaded with full range woofers. The whole point of adding a 6" mid to a cab is to have it take over above the crossover point where dedicated woofers go lower, but can't go as high.

A 12/6 fEARful utilizes a 6" mid because the 3012LF is a monster low end woofer that needs the mid to carry on above it's limitations in the mids/highs. The 3012LF is not a full range speaker so it needs the mid. I understand the budget concerns, but in the long run, you'd get more building a 12/6 and selling the 212.
 
#4
Sundogue said:
Not much point in adding a mid driver to a cab loaded with full range woofers. The whole point of adding a 6" mid to a cab is to have it take over above the crossover point where dedicated woofers go lower, but can't go as high.

A 12/6 fEARful utilizes a 6" mid because the 3012LF is a monster low end woofer that needs the mid to carry on above it's limitations in the mids/highs. The 3012LF is not a full range speaker so it needs the mid. I understand the budget concerns, but in the long run, you'd get more building a 12/6 and selling the 212.
Click to expand...
That's part of the equation, but equally significant is the directional properties of a 12" driver, full range or not.

A very quick calculation (I could have a brain fart) tells me the 12" starts getting directional around 600 Hz, so a mid would definitely be useful for that purpose.
 
#5
Sundogue said:
Not much point in adding a mid driver to a cab loaded with full range woofers. The whole point of adding a 6" mid to a cab is to have it take over above the crossover point where dedicated woofers go lower, but can't go as high.

A 12/6 fEARful utilizes a 6" mid because the 3012LF is a monster low end woofer that needs the mid to carry on above it's limitations in the mids/highs. The 3012LF is not a full range speaker so it needs the mid. I understand the budget concerns, but in the long run, you'd get more building a 12/6 and selling the 212.
Click to expand...

Not sure if it matters either way, but according to Avatar's website the 12 is a "Eminence Delta LF speaker". I can't recall the exact model number, but it can get pretty low without breaking up.

EDIT: I believe [Invalid or Expired Link Removed] is the driver used.
 
#6
Your Avatar cabs are good candidates for the addition of a 6" mid driver. Your biggest hurdle is going to be adding a separate chamber for the mid in a pre-built cab. I can't tell if there is room to do this but it is necessary. I got around that problem in my past projects by adding a closed back mid so the mid chamber was unnessesary.

It is my understanding that 12" drivers are fairly non-directional up to about 2kHz. I think 800Hz is a good safe bet when crossing a typical 6" driver with a 12" driver but I have gotten good results anywhere between 500Hz and 1.6kHz. The crossover is more dependant on individual components than tonal goals. In my above case I chose 1.6kHz because the closed back design can have some nasty artifacts below 1kHz and my woofer is capable of decent mids up to that point. Once you decide on the drivers you will then be able to make an informed decision on the crossover.
 
#8
The 12 won't start beaming 'til 1k or so. 800 is a good spot for the alpha6 as it runs 95ish db from 1k up, 93 or so below that. The issue is the prebuilt xover. Neither driver is 8ohms at that frequency and their curve will rise some when the coils heat up. They're close enough it'll work for driver protection but rolling your own will work better. You can use a dogfood or cereal bowl with stuffing inside for a mid subchamber if building a box within the box is too much PITA. That volume must be subtracted from the space the woofer has to work in. Might require retuning, might not.
 
#9
Sundogue said:
Not much point in adding a mid driver to a cab loaded with full range woofers. The whole point of adding a 6" mid to a cab is to have it take over above the crossover point where dedicated woofers go lower, but can't go as high.
.
Click to expand...
I believe the Avatar is loaded with Delta 12LF; I hope so, as the Delta 12 is horrid for electric bass. And the overwhelming reason for a midrange driver isn't extension, it's dispersion.
The Alpha 6 wouldn't be my choice, as it needs a separate enclosure, I'd do a Alpha 8MRA if it will fit, a LA6-CBMR if it won't, crossed over at 1kHz to 1.6kHz. There's no advantage to going lower, even with Delta 12LFs. I'd use the PXB2:1k6. Be sure your cab is 8 ohm, you can't use the PXB with a 4 ohm woofer set. You'd have to high pass the mid only with no woofer low pass if the cab is four ohms.
 
#10
I have a "F'avatar". Faital Pro 6 for the mids, Avatar 12 neo-extended xmax for the lows loaded in a fEarful 12.6 cab - the 12.6 is very to the SB112 cab. Currently, the cab is biamp only and I'm using 800 as the x-over point. It sounds great - more or less like my existing fEarful12.6 but with a less massive low end. Less 'heft'.

So another alternative for you would be using the CBG 800 hz crossover for the 12.6 available from SpeakerHardware.com or to source the CBG 12.6 xover parts and DIY.

BTW - I use the AlphaLite 6 in my 12.6 cab and like it a bunch. If you want to save a little weight, that would be an option. The Faital I bought here from the GFS. Not sure what they cost new but it's a nice sounding speaker. The B&C MD638 is another really nice driver for your application. My original 12.6 used that one. The top end goes higher than the Alpha and it's way smoother up top. t has a much 'sweeter' sound.
 
#11
billfitzmaurice said:
I believe the Avatar is loaded with Delta 12LF; I hope so, as the Delta 12 is horrid for electric bass. And the overwhelming reason for a midrange driver isn't extension, it's dispersion.
The Alpha 6 wouldn't be my choice, as it needs a separate enclosure, I'd do a Alpha 8MRA if it will fit, a LA6-CBMR if it won't, crossed over at 1kHz to 1.6kHz. There's no advantage to going lower, even with Delta 12LFs. I'd use the PXB2:1k6. Be sure your cab is 8 ohm, you can't use the PXB with a 4 ohm woofer set. You'd have to high pass the mid only with no woofer low pass if the cab is four ohms.
Click to expand...

I guess my (admittedly flawed) thinking was that with a crossover at a lower frequency, the mid driver would produce more of the mid to high-mid frequencies, and the LF would produce everything below that. If it's simply going to produce the same frequencies as the tweeter, it would, to me, be a waste of time. Is my understanding correct?
 
#12
I have a SB112 that does admirable duty as an end table or speaker stand. I sometimes consider dropping in a 3012LF and some kind of closed back mid, re-doing the crossover, maybe adding a bit of bracing and having a 12" nEARful for the efforts.

What ends up stopping me is the expense and effort of doing this only to have something that's "near".

If you start adding up the parts and time you're not that far from the real deal, and only to get something that's not really ideal in any of the aspects.

-'close' box size.
-'maybe close' porting
-'possibly passable' crossover
-'not great but not awful' closed back mid


Eh. It always looks like more than I want to spend for a gamble, and not a 50/50 bet either.
 
#13
The mid driver is crossed over lower and doesn't go as high as the tweeter so the two don't reproduce the same frequencies. As Bill mentionned earlier, the mid driver will give better dispersion of the upper mids and low treble frequencies which will make the cab sound more even off axis. Those upper mids and low treble will also probably be smoother with less breakup (than if reproduced with a 12" driver) and will affect the voicing in that region. A 12/6 cab is a well balanced configuration that sounds very good but will sound different.
 
#14
NicJimBass said:
I guess my (admittedly flawed) thinking was that with a crossover at a lower frequency, the mid driver would produce more of the mid to high-mid frequencies, and the LF would produce everything below that. If it's simply going to produce the same frequencies as the tweeter, it would, to me, be a waste of time. Is my understanding correct?
Click to expand...
Which driver reproduces the frequencies in question is moot, as twelves are perfectly capable up to at least 1.6kHz. But two twelves will handle at least eight times the power at 500 Hz as one six, so there's no benefit to crossing over there. Above 1kHz the mid driver has wider dispersion than twelves, so above 1kHz is where it's worthwhile running it. With only one mid driver I'd stay higher, 1.6kHz, to be able to keep up with two twelves. As for the tweeter, it does nothing below 4kHz, while the twelves have no useful output above 2kHz. The mid fills in that response hole.
 
#15
billfitzmaurice said:
Which driver reproduces the frequencies in question is moot, as twelves are perfectly capable up to at least 1.6kHz. But two twelves will handle at least eight times the power at 500 Hz as one six, so there's no benefit to crossing over there. Above 1kHz the mid driver has wider dispersion than twelves, so above 1kHz is where it's worthwhile running it. With only one mid driver I'd stay higher, 1.6kHz, to be able to keep up with two twelves. As for the tweeter, it does nothing below 4kHz, while the twelves have no useful output above 2kHz. The mid fills in that response hole.
Click to expand...

I'm starting to understand... thanks for the lesson!
 
#16
BurningSkies said:
I have a SB112 that does admirable duty as an end table or speaker stand. I sometimes consider dropping in a 3012LF and some kind of closed back mid, re-doing the crossover, maybe adding a bit of bracing and having a 12" nEARful for the efforts.

What ends up stopping me is the expense and effort of doing this only to have something that's "near".

If you start adding up the parts and time you're not that far from the real deal, and only to get something that's not really ideal in any of the aspects.

-'close' box size.
-'maybe close' porting
-'possibly passable' crossover
-'not great but not awful' closed back mid


Eh. It always looks like more than I want to spend for a gamble, and not a 50/50 bet either.
Click to expand...


I spent several weeks researching a fEarful build, looking at pricing, sourcing materials, etc., and it all became too much, ESPECIALLY since I'm trying to do things on a budget. I was able to get 2 SB112's from a fellow TB'r at a price I was more than happy with, and for what I play, they do well... my whole goal it to take good and make it better, not take good and make it fEarful (despite what my original post may have implied). What Bill has suggested seems like it'd work, for me... there are lows, some mids and the tweeter... there is a hole that I'd like to close up, and I feel I can do it on a limited budget. Not looking for perfection, just looking for improvement.
 

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