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Vox 3012LF/Alpha 6A cabinet tests

#21
Greenboy, the K140 is a pretty beefy 15 from the TS specs I see. Fs of 30, ~5.1mm xmax, I calculate around 450vD. With its 98 db sensitivity rating, shouldn't a single one be slightly louder than a 3012LF (once you pour the watts on)?

This is what I am working off of:
Invalid Link Removed
 
#22
2 woofs and a mid would probably get you closer as would doing away with the really low 40something hz stuff. I'd go back to the model of the one you have now and cut the internal volume in half and see what it does to the lower end of the curve...see if it's something you can live with. A lot of cabs have that hump in the midbass and sound good but too much of it leads to boom and indistinct pitch on the low notes.

May want to experiment with a 45 and a 50hz port tuning on the current cab to see if it does anything about the farting. When something's tuned too high it makes the speaker start working again below the tuning frequency and excursion goes up real far real fast.

Just ideas....
 
#24
johnk_10 said:
well, i don't think that i'm doing anything wrong. the cab is tuned to 55 hz with 2.4 cu ft volume and there is no chuffing at all (vent mach .04).
Click to expand...

Two 3" ports in that size of box at a 55 Hz tuning means each port tube is around 3" deep. And you have enough cross section to drive strong LF content with about 50 watts. That combined with a tuning that's way too high... hmmm : |
 
#25
greenboy said:
Two 3" ports in that size of box at a 55 Hz tuning means each port tube is around 3" deep. And you have enough cross section to drive strong LF content with about 50 watts. That combined with a tuning that's way too high... hmmm : |
Click to expand...

yep, they currently are 3" deep, and the cab actually doesn't sound or feel like its tuned very high, but i may re-tune it to 45hz with two 3" x 5.5" vents instead.
 
#27
i modifed the baffle board today to accomodate two 3012LF's and the Alpha 6A and retuned the cab's ports to 45Hz. just waiting for the other 3012LF which is scheduled to be here wednesday evening. i'm going to start testing it with a 12dB/octave x-over with 750hz LP and 1000hz (or 1500hz) HP xo points, but i now have quite a few more coils and caps, so i can basically massage the XO wherever i want it to be.
i'll also might try crossing the 3012's over at 625hz and the Alpha at 1khz, both with 6dB slopes, to see if i like that better, as i sometimes prefer using a more gentle 6dB slope since it uses less components and, sometimes can sound smoother. after these mods, i expect the cab to be alot more comparable to my 2x15 JBL K140 cab.
 
#28
i thought i'd post an update on this cab now that the other 3102LF arrived.

i've only had a few minutes to test it before i might be disturbing my neighbors :eek:.

i built a new 2nd order x-over with a low pass freq of 850Hz and a high pass freq of 950hz and the cab sounds great now, and with just some minor eq'ing, i can make it sound very similar to the dual K140 cab. the JBL cab is still the 'magic' box for me, as they are noticeably more efficient and have a little more detail, punch, and fullness in the low end, but this little 2x12/6 is, surprisingly, almost its equal. i may install an attenuator for the Alpha 6A so i can dial it back just a tad, since the cab is just a teensy-weensy bit brighter than the JBL's, but overall, i'm very pleased with the results.

BTW, when retuning the 2x12 cab, i re-measured and re-calculated its cabinet volume and it has a volume of 2.7 cubic ft (i thought that it was 2.4), and by lengthening the ports to 5.65", it is now tuned to 42hz.

i spent a lot of time an money on this project/experiment, just to see what all the rave was about regarding these new neo 3012LF woofers, and while i really couldn't be much happier with the results, i still contend that the old JBL K140's have yet to be surpassed with modern technology. however, when you consider that this cab is less than half its size and weight, and sounds very close, all the work and expense has paid off.

i'm also hoping that the cab will end up losing a little of its stiffness once the drivers are broken in a bit.

i'll try to post a sound file tomorrow so those that have been following my progress can compare the two cabs again.

thanks to all of those for your suggestions!
 
#31
Before you call shenanigans on the K140's being surpassed, you should compare a single 3015LF to a pair of K140s :) Should be right about the same volume when pushed hard. The high output midrange is a lot more expensive than an Alpha though.
 
#32
I was concerned John that you might linch me for even suggesting this mod...

I have spent too much time in the reading room lately and have been thinking about ordering up a pair of 3015LF's or maybe even 4015LF's for one of my AMPEG 215's.

I was thinking if I cut a big circle out of the divider it would act like one big cab.

I wonder if that would be a foot stomper?

BOB
 
#33
yeah. at the amps' same volume setting, its a little less efficient than the 2x15, but the gk 1001RII head that i'm running it with has plenty of power to make up for the difference. now with two 3012LF's and with the cab tuned lower, i pushed it pretty hard for a moment and didn't notice it farting out like it did before.

in a blind test, with a little eq adjsutment, tone-wise, i think that alot of people might have a hard time distinguishing which cab is which. and being a non-tweeter/horn/x-over guy, having just the one Alpha 6A is perfect for my taste. i may even dial it back a hair, but its pretty good the way it is, when i twist the eq knobs, the whole cab is very reactive to it. i also like the idea of the mids- highs coming thru a small paper cone as opposed to a horn or tweeter.

in doing all of these tests, it just confirmed for me just how great the K140's are (for my taste). its very hard to describe, but they just have this full range clarity, almost HiFi-ish smoothness and fullness that no other speaker has ever captured. even though JBL's spec sheet says that they only go up to 2500hZ, all six of mine easily go up to 4-5k khz and don't require a mid or tweeter to get their transparency.
 
#34
johnk_10 said:
i spent a lot of time an money on this project/experiment, just to see what all the rave was about regarding these new neo 3012LF woofers, and while i really couldn't be much happier with the results, i still contend that the old JBL K140's have yet to be surpassed with modern technology.
Click to expand...

But have you compared a dual 3015 cab to a dual K140 cab?

Alex
 
#35
rpsands said:
Before you call shenanigans on the K140's being surpassed, you should compare a single 3015LF to a pair of K140s :) Should be right about the same volume when pushed hard. The high output midrange is a lot more expensive than an Alpha though.
Click to expand...

it might have the same output, but IMO, it'll never get the transparency or the tonal voice' of the gerbils (JBLS). every eminence speaker that i've owned and/or still own (and i have quite a few of them), while i like and use some of their models, they're just a bit cloudier by comparision. i haven't had a 3015LF. but i did have a pair of 3015's in the beatle cab and they sounded loud, but harsh to me, then i installed the K140's and it was like love at first sight, and a whole new (old) world opened up. IMO, they have a bigger soundstage that is way better balanced throughout their entire frequency range.
 
#36
rbonner said:
I was concerned John that you might linch me for even suggesting this mod...
BOB
Click to expand...

actually, i want to thank you. in the back of my mind, i was kinda heading that way anyway, but i didn't want to go there if i didn't have to (yeah, like that was going to happen :rolleyes:).

its a great cab now, and i can't wait to really spend some time with it tomorrow, at band rehearsal this sunday, and on the gig in a week.
 
#38
johnk_10 said:
two 3015's? yes. (i didn't like them)
two 3015LF's? no.
Click to expand...

it have the same output, but IMO, it'll never get the transparency or the tonal voice' of the gerbils (JBLS). every eminence speaker that i've owned and/or still own (and i have quite a few of them), while i like and use some of their models, they're just a bit cloudier by comparision. i haven't had a 3015LF.
 
#39
rpsands said:
Greenboy, the K140 is a pretty beefy 15 from the TS specs I see. Fs of 30, ~5.1mm xmax, I calculate around 450vD. With its 98 db sensitivity rating, shouldn't a single one be slightly louder than a 3012LF (once you pour the watts on)?

This is what I am working off of:
Invalid Link Removed
Click to expand...
The low Qts chokes off response below 100 Hz.
i did have a pair of 3015's in the beatle cab and they sounded loud, but harsh to me, then i installed the K140's and it was like love at first sight, and a whole new (old) world opened up.
Click to expand...
Purely the result of age and use. Older drivers sound smoother simply from being very well broken in. With accelerated break-in over the course of a few days the initial harshness of new drivers can be fixed. Or you can just play them for a few years.
 

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