Vox 3012LF/Alpha 6A cabinet tests

[johnk_10]

i've been playing around with the crossover points on my vox (3012LF/Alpha 6A) cab today and after trying a few different X-O freqs, i've decided that i'm going to try crossing over the 3012LF at 900Hz, and the Alpha at 1150Hz (and also try1400Hz). i was playing around with eq'ing the cab and it seems that it was just too strong for my taste in the 1k-1.3K range. just trying to scoop it out a little in the middle rather than have to use EQ to correct it. i should have the new coils and caps by monday afternoon.

here's how it sounded last night as compared to my super beatle cab, loaded with two K140's. (the 3012 cab is the first 4 bars and the JBL is the second 4 bars).

http://johnkvintageguitars.homestead.com/3012LFJBLK140_test_two.wma

 

[rpsands]

My computer speakers are nothing special but the sound isn't magnificently different to me. The 3012LF sounds a LITTLE deeper but not amazingly so

I am really impressed with the Alpha 6a's sound. Makes me wonder if a pair of those and a pair of 3012LFs would be a better way to go for a 2x12 cab than a 6nd410 (about half the price for a few pounds of weight).

 

[johnk_10]

i'm actually happy with it, but i'm going to tweak it a little more. the JBL's just have a little more growl and are a little less pronounced in the mids and mid bass. but the 3012LF cab does have alot of immediacy and punch. i'm just trying to get it to sound as close to the big 2x15 cab as i can, but it does put out a surprising amount of bass for a single 12" and i can feel the wind coming out of the vents when i push it.

 

[rbonner]

JOhn, is there room to put a second 3012LF back in the hole and wedge in the 6A? That would boost the bass and also tame the 6a down a bit, just a thought? Just read RP's post... I dont think the second 6A would be necessary though.

BOB

 

[johnk_10]

John, is there room to put a second 3012LF back in the hole and wedge in the 6A? That would boost the bass and also tame the 6a down a bit, just a thought?

that's funny Bob. i was thinking the same thing today. two would fit , but i'd have to make a new baffle board for it, and i really don't know if i want to go that far with it. its actually very close to what i want to get out of it right now, i think that i just have to massage the x-o points more to my liking.

 

[johnk_10]

just ran a few more crossover tests with only the caps and coils that i have on hand. i tried it with a 1st order XO (6dB/octave roll-off) crossing the 3012LF over at 670hz and crossing the 6A over at 1400hz and its just about exactly what i want. getting more caps and inductors on monday and will try a 2nd order crossover (12dB/octave) at 700/1250 and see if i like that better.

 

[rbonner]

that's funny Bob. i was thinking the same thing today. two would fit , but i'd have to make a new baffle board for it, and i really don't know if i want to go that far with it. its actually very close to what i want to get out of it right now, i think that i just have to massage the x-o points more to my liking.

OK I'm going to crank on you. As much of a perfectionist as you are.... You should do it even if it is just a test, leave the grill cloth off until afterwards, but I bet it would be a great box.

 

[DukeLeJeune]

Johnk, it sounded to me like your 2x15 cab (from the other thread) may have an upper bass hump so the first two overtones are quite strong, but the fundamentals themselves are probably not as strong.

My guess is the single 3012LF is fairly "flat" down to somewhere in the upper to mid 40's, which doesn't really mimic the response of the 2x15... but might come close with a bit of EQ. Have you tried that?

Adding a second 3012LF may not be the fix, or at least not the whole fix, but without knowing the internal volume and tuning frequency I can't say for sure.

 

[johnk_10]

Hi Duke,
the internal volume is 2.4 cu. ft. and the ports are round 3"x3" each, so IIRC, its tuned it to 55hz. its getting closer with the 670hz/1400hz 6dB/oct. x-over. i think i may build another xo but with 12db/oct. & a volume control for the 6A.
i have tried eqing it and it does get closer, but i'm trying to get the cab to sound closer to the way i want it without using eq.

 

[johnk_10]

well, after running alot more tests, i have found that there is NO way that a single 3012LF is going to have anywhere near the output or fullness when compared to the two K140's, so my next plan of attack is to get another 3012LF (thanks alot Bob-sarcastically ) and mount it next to the one that's in there. i can actually use the same baffle board but will have to flip it upside down, cut a 6" hole for the Alpha 6A, re-brace it to the back of the cab, and reposition the Vox logo on the front. i'm just going to use one Alpha since, for me, it has way more than enough high end, as compared to the JBL's, and i already have a 750hz/1500hz x-over with an adjustable mid control so i can further dial in the 6" mid driver to my taste.

in summary, IME, for those that think a single 3012LF can compare to the output of two JBL K140's, you may want to rethink your plans as well.

here's a pic of my new plan for the baffle modification:

many thanks to DukeLeJeune for corresponding with me via email and helping me with this!

 

[rpsands]

I would suggest that a single 3015lf would compete with. Two 140s

 

[rbonner]

See the problem RP is he had a two 12" cab just sitting there awaiting massive modifications.

BOB

 

[rpsands]

Yar, I guess what I'm getting at is there's really no reason to think that a 3012LF would keep up with a pair of K140s. A K140 has very close to the same vD as a single 3012LF by itself and 3db more sensitivity (despite possibly being more sensitive down at the very bottom).

Two K140s then is going to have probably 6-9db more volume than a 3012LF.

On the flipside a 3015LF has almost twice the vD of a K140 and a higher sensitivity, so definitely a better choice as a replacement.

If you've got 12" cabs, you've got 12" cabs though, so make of it what you will.

 

[johnk_10]

before i installed the JBL K140's in the large beatle cab, i first tried it with two 3015's (non LF's) and the cab didn't sound any more efficient, just a bit louder in the mids, which i thought was okay, until i took them out and tired the JBL's in it. to me, the JBL's sounded so much better, i immediately sold the 3015's. the 3015's were harsh and cloudy by comparision.

if a 3012LF is anywhere near similar to a 3015LF, i still think that one 3015LF would fart out before the two K140's will, because the single 3012LF does it way before the pair of 140's does, at a much lower SPL.

 

[rpsands]

A Kappalite 3015, if JBL's posted TS specs are correct, has right about the same amount of excursion as a K140 but 2-3db more sensitivity. So I would not expect it to do anything but perform at least as well and weigh like 1/3rd to 1/5th as much - the difference in volume would not be terribly noticeable outside of the mids (if at all).

The tone is a sculpting/preference thing so I can't comment on that.

A 3015LF however, is slightly more sensitive and has almost twice as much excursion as a K140, so you can expect it to be as loud as two K140s, if crossed over correctly so you don't deal with that MONSTROUS upper mid peak, and if you run a high output midrange.

3015LF vs. 3012LF - 3015LF is 3db more sensitive and has roughly twice as much peak displacement. It will get almost as loud as a pair of 3012LFs (with sufficient wattage).

 

[greenboy]

Yar, I guess what I'm getting at is there's really no reason to think that a 3012LF would keep up with a pair of K140s. A K140 has very close to the same vD as a single 3012LF by itself and 3db more sensitivity (despite possibly being more sensitive down at the very bottom).

A lot of that is immaterial when you have a dedicated mid driver anyway, further compounded by all the variables you can introduce intentionally or not when working with a handful of crossover components. All that stuff is tremendously interactive, reactive. Like any LCR stuff, it gets wicked.

 

[greenboy]

i still think that one 3015LF would fart out before the two K140's will, because the single 3012LF does it way before the pair of 140's does, at a much lower SPL.

You must be doing something seriously wrong then, with cab tuning, or you don't have enough vent cross-section to keep chuffing out of the picture. I used to work with a lot of the classic JBL drivers and they in no way can deal with low end like the Kappalite LFs.

 

[johnk_10]

You must be doing something seriously wrong then, with cab tuning, or you don't have enough vent cross-section to keep chuffing out of the picture. I used to work with a lot of the classic JBL drivers and they in no way can deal with low end like the Kappalite LFs.

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). when pushed hard, all the farting is coming from the 3012LF driver itself

let me say that i'm not knocking the 3012LF drivers at all. i mean, i just bought two of them and i've never heard a single 12" put out so much low end. its just that, IMO, while a 3102LF might outperform two K140's in spec's on paper, it definitely hasn't come even close in my 'real life' tests.

 

[will33]

I don't know if I'm getting your plan but if it's to put 2 drivers in the same box that now has 1, it'd be the same as putting 1driver in 1.2 cu.ft. or a little less as the second driver would take up a little space too. Then the 40's and 50's hz stuff would be gone and there'd be a big hump above that. There would also be the need for more port area to keep chuffing at bay, maybe 4" pipe or a 3rd 3".

If you're talking about making a second box like this one, the 2 would sound the same as your one does now, just louder.

2 woofers and just the 1 mid and it'd be like taking the one you have now and 3-6db boosting everything below the current crossover point or 3-6db cutting everything above it.

 

[johnk_10]

I don't know if I'm getting your plan but if it's to put 2 drivers in the same box that now has 1, it'd be the same as putting 1driver in 1.2 cu.ft. or a little less as the second driver would take up a little space too .

yep, that's my plan.

Then the 40's and 50's hz stuff would be gone and there'd be a big hump above that. There would also be the need for more port area to keep chuffing at bay, maybe 4" pipe or a 3rd 3".

its not chuffing now, but i might go with 4" ports with two 3012LF's.

If you're talking about making a second box like this one, the 2 would sound the same as your one does now, just louder.

yeah, i know. i'm just going with a single 2x12 box.

2 woofers and just the 1 mid and it'd be like taking the one you have now and 3-6db boosting everything below the current crossover point or 3-6db cutting everything above it.

that sounds just about exactly what i'm looking for. the mid driver is too loud for me right now.