A Mysterious Cab

FriendlyFiver

FriendlyFiver

Dec 19, 2018
77
78
4,551
Sacramento
#1
Greetings TB Friends,

While perusing Craigslist with a mild case of GAS, I came across the "I dunno what it is but I'mma sell it" kind of post we all hope for. At least I think I did. Read on Gentle Reader, read on....

It was advertised as a 2x10" cab, with only a single 1/4" TS male jack, hardwired, clearly meant for cab & head service; the cable isn't even quite 30" (70 cm) long. An arrangement was made, payment transferred, I picked it up and brought it home.

Here's some pics:
Resized952019080395133901.jpg
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Four nicely-sized casters (the two in back are locking), decent cab shape, back plate is secured with no fewer than fourteen (!) 3" screws (thanks be for powered screwdrivers!).

The front screen has some damage, not much, and is still quite taut. Notice the distinctive fading of the front screen; it looks to me like there was some kind of decoration on the front at one point.

The cab appears professionally-made, it's super strong and has lots of handles and there are screw-holes evident where something was once more or less permanently attached.

"But what's inside?" I hear you ask. Well, I'll tell you:
IMG_7417.jpeg


What was sold as a 2X10" cab, is actually a 1x10" (JBL model K110, 8 Ohm) plus a 1x15" (ElectroVoice SP15A, also 8 Ohm) cab.

My PA won't drive it (requires active sub), but I did the 9V battery test, and boy-howdy, it wants to make some noise!

So, dear friends, I have three questions:

1. Clearly, this is a passive cab. How do I make it work with a PA that requires an active subwoofer?

2. The back panel is solid; should it be ported, and if so, in what manner?

3. Since I don't know what I don't know, what else should I know or ask?

Thank you for your patience, this is my first foray into the world of cabinets, much less used Mystery Cabs from the Internets.
 
#2
Pretty good score on those drivers, if you have a use for them! Unfortunately I don't think those will stand up to subwoofer useage, and definitely not while they are sharing the same box.

But to answer your questions, to make it an active subwoofer you'll need to get a power amp for it.

Porting is really out of the question here because the drivers don't match and are not designed for that enclosure.

Honestly, the best thing you can maybe do is replace the drivers with the proper size drivers, something more modern and designed for subwoofer use, and keep it sealed.
 
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#3
mmbongo said:
Pretty good score on those drivers, if you have a use for them! Unfortunately I don't think those will stand up to subwoofer useage, and definitely not while they are sharing the same box.

But to answer your questions, to make it an active subwoofer you'll need to get a power amp for it.

Porting is really out of the question here because the drivers don't match and are not designed for that enclosure.

Honestly, the best thing you can maybe do is replace the drivers with the proper size drivers, something more modern and designed for subwoofer use, and keep it sealed.
Click to expand...
Thanks for the input! Exactly the sort of thing I need to know!

So if it's not used as a sub, but instead as a cab with a head, would the drivers still need to be replaced? If so, then with what? The cab is clearly big enough for 2x15", but are there reasons to use matched 10" or 12" drivers?
 
#4
Yes the drivers would need to match since they are sharing the same air space. Right now they will just work against each other. This is a concern if you want to use it for low frequencies but not as much if you just use it for mids and highs.

Also another reason I say it won't make a good sub is because that EV driver is rated to handle only 50 watts so it's not a high power driver.

The cab might be big enough to hold a 15, but that doesn't mean there is enough airspace for 15's. I see a plywood spacer in front of that 15, and an obvious spacer for the 10. What size drivers was it made for orignially?
 
#6
mmbongo said:
Yes the drivers would need to match since they are sharing the same air space. Right now they will just work against each other. This is a concern if you want to use it for low frequencies but not as much if you just use it for mids and highs.

Also another reason I say it won't make a good sub is because that EV driver is rated to handle only 50 watts so it's not a high power driver.

The cab might be big enough to hold a 15, but that doesn't mean there is enough airspace for 15's. I see a plywood spacer in front of that 15, and an obvious spacer for the 10. What size drivers was it made for orignially?
Click to expand...
Well, as you know from reading my story, I have no idea as to the history or provenance of the cab. Perhaps it was a professionally-made box, and someone added their own drivers? I don't know how old the JBL 10" is, but it has a price tag of $99.00 (presumably USD).

I know next to zero about cab-building, but I can see how mismatched drivers might interfere with each other, strictly based on displacement in a closed environment.

So, what to do? Throw in a matched pair of 10"s? 12"s? If so I'll need new spacers.

Also, does anyone have any idea about the fading on the front screen?
 
#8
It won't take much to destroy both of those drivers.

IF the drivers are functional, they are both worth more as parts than the cabinet you have there.

The EV SP-15A was post SRO era and was higher power handling. It was quickly replaced by the EVM series which had a very long production life.

The JBL K110 is not "really" a woofer but more of a mid bass driver. It absolutely should not share the same air space as the EV driver. It's great driver for some specific applications but not for what you are looking for. The cabinet you have was modified to mount the driver in a terrible attempt to do something, but I have no idea what.

My suggestion is to sell what you have and buy something that actually works for your needs and is a finished, commercial production cabinet. That way you know what you are getting. The K-110 if it's in good condition is probably worth $100 on its own.
 
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#9
mmbongo said:
I'd like to hear thoughts from others though! My word is not gospel!
Click to expand...

I owned and gigged with an SP-15A driver for quite a few years. It lived in a couple of different cabs and I actually preferred it to either EVM15L and 15B for my purposes. What the OP's pics don't show is this:

SP15A_EV.jpg



The whizzer cone made it work pretty well in a smallish ported wedge cab under my workbench for general purpose testing of audio gear, but eventually I put it in a retuned TL606 cab and used it pretty happily that way for bass, guitar, keys, and general monitoring. I acquired it a a very long time ago, but IIRC it was rated for something like 150 watts. @agedhorse is likely to have better hard info on that though.
 
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#13
FriendlyFiver said:
So, I got it wired to the right channel of my PA (Yamaha 400bt, so passive channel), and WOW does it sound big! Both drivers work great, the sound is strong, effects are clean.
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Be careful, or you will end up with damaged drivers. If it's really 400 watts, you arecway over what the drivers can take in a shared air space (no matter what you may think)
 
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#14
The problem with any used cab is that you never know how it was driven and/or abused. Better if you know the seller who can vouch for how it was used. Otherwise, it really is a gamble.
 
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#19
The JBL is a very efficient speaker for guitar amps - not for bass. I don't know much about the EV.

The cabinet looks like a copy of a 60s Fender Bassman/Bandmaster cab. The real thing would have two 12" speakers and a board dividing the two drivers, to which the back would attach.

Truthfully, the cabinet without the drivers is hardly worth what you paid. Even the authentic Fender cabs of that design are not good for anything but looks and loud guitar players. But the drivers are worth a fair bit in the used market.
 
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#20
I’d have to say that cab or drivers will not do what you need it to do. At best you can throw some power at it and blow the speakers. At worst, the speakers are already blown from someone using the cab like that.

Test out the speakers, then sell them separately. Then sell the 2x15 cab separately. Then use that money and look for an oem purpose built sub for your PA.

I fear one or both speakers might be blown from being used in that manner in that cab, but if one of them isn’t blown, you’ll easily turn a profit from your $20 investment.
 
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