Converting guitar cab to bass cab

[matthabens]

Hello all,

I've acquired a Harley Benton 4x12 guitar cab for a tenner which I was going to convert to a bass cab. I've only just thought of crossovers etc in the conversion. Will it be as simple as to just replace the speakers or will I have to replace the crossovers as well? I bought it as I couldn't even buy the timber to make a cab for £10! I will be running it from a torque T2001EBH 200w head if you need to know the running gear.

Thanks in advance for any help

Matt

[Dad3353]

Good evening, Matt...

The HB cab has crossovers..? Normally they'd only be fitted if there was a tweeter in there; I don't think those cabs have tweeters (I could be wrong...).
Why do you want to change the speakers..? Are the originals 'shot'..? You'll not be able to transform this into a rival to the top-end cabs, but 'back then', guitar cabs, and 4x12s were very common. The structure and design of a 'standard' 4x12 doesn't lend itself to 'proper' bass use, so I'd suggest just using it 'as is', if the cones are OK, or fitting a set of decent 12" speakers that aren't too expensive. Don't go mad looking into top-end stuff; it'll be wasted in such a cab.
You could, of course, tart it up for guitar, sell it on as such and buy a bass cab..!
Just my tuppence-worth; hope this helps.

[matthabens]

Thanks for the reply and good point about the crossovers, no there are no tweeters. So the current speakers should be able to handle bass playing without too much trouble then? If I had a choice I'd be down my local shop and buying a new cab and head but I have my wedding coming up in august and need to keep costs down! I've been playing for about 9 months and my wedding is going to be my first gig so seemed a cost effective way of having something that's man enough for small venue work. As I'm not 100% with electronics I just assumed guitar speakers couldn't drop low enough to handle bass work but then again the badge does say 70hz to 5khz and 250w RMS so do think it will be ok through the 200w head?

[Dad3353]

If you read up a little, elsewhere in the forum, you'll learn that bass is not only about 'low'; in fact, it's hardly about 'low' at all..! The only real test is to try it and see. If you're not playing 'full tilt' with a sub-human drummist and a full stack guitarist, you'll soon enough know if the sound is agreeable to you (all...), or not. If it starts to distort, back off some, or reduce the bass part of the spectrum. If you're reasonable careful, it'll last the year, and you can save up in the meantime towards acquiring a more suitable cab. Don't bust it, though, or you won't be able to sell it on at a later date.
Good luck with it all; we all start somewhere, so make the most of it and enjoy.

[Bill Fitzmaurice]

There's far more to a bass cab than just using drivers intended for bass guitar. For one thing done correctly a bass cab will have roughly twice the internal volume of a guitar cab using the same size drivers. IMO don't throw away good money after bad, use it as is, when you're able to afford it get a proper bass cab.

[chris_b]

I'd leave this cab the way it is and rate it at half the watts for bass.

[Beer of the Bass]

I don't know the measurements of this cab but there can't be more than about 30 litres of cab volume per driver, which is small for a bass cab. If you can live with the bass response being fairly lean there are some drivers that would work in a sealed cab that size, but by the time you've fitted four drivers you're out by £200 minimum. That would be better spent on a secondhand bass cab or on building something more suitable from scratch.
I've played bass through unmodified 4x12" guitar cabs on a couple of occasions; if you don't push the low end too much they can actually sound OK and reach volumes you could use in a small venue. You don't have much to lose by trying this, given that you got the cab so cheaply.
If it distorts, you can either turn it down or have fun pretending you're JJ Burnel!

Edited February 9, 2015 by Beer of the Bass

[matthabens]

I'm very much still in the early stages i think! I hadn't considered any of the points you all mentioned! I think i will run it as is without pushing too much through it, in all honesty by the time i start seriously gigging i may be able to afford a better rig anyway, so i'll leave it and play through it, just clean it up, re castor it, re cover it etc so i can sell it on next year. No point plowing £200 into new drivers, like you said thats half a new cab anyway!
Thanks again to all for waking me up to a few points and i'll see how it runs

[Musky]

FWIW I've had a guitar 4x12 for bass duties for over 30 years. Other stuff has come and gone but the 4x12 has remained - admittedly it hasn't been gigged for the last 10 years but that's because it's a pain in the arse to shift! It was mostly gigged with an amp putting out 180W into the 200W cab with no ill effects, though someone did manage to damage one speaker (it needed a recone) when it was lent to a mate for his rehearsal studio for 6 months. Not to shabby considering I'd walked in there to see every control on the amp maxed out on one occasion.

Just don't expect any real bass from it and be aware that you may get a different result to me if you push it too far.

[Phil Starr]

Guitar speakers are designed with short voice coils, because they don't have to move too far and because it makes them louder (don't we know it) Bass involves moving further to move more air and this is what damages the speakers. Whether your HB's will get damaged depends upon their detailed design but this is all volume dependent, the speakers in your clock radio could probably handle 1W of bass. Feel free to play through a guitar cab at low volumes.

If you roll off the bass a little then 3dB of roll off will allow you to double the power you can use, then cutting some of the top will make it sound bassier and you might get a decent volume, any bass boost and you'll probably lose the speakers.

There are plenty of speakers that you could try in a cab like this which would handle bass better but will all cost £200 and upwards as you surmise. Most will give you an old school style bass hump in the upper bass and little low bass, the cost of putting speakers in a cab which is too small. If you want to build a project then great, we'll help you, but honestly you are probably better off using it as it is, controlling the volume and bass controls. £200 will buy you a decent second hand cab especially if you are prepared to lug something like a 4x12 around.

Edited February 10, 2015 by Phil Starr

[Dan Dare]

Following on from Bill's point, why not use fewer drivers, say 2 proper bass 12s, place diagonally with the unused holes blocked off? That'll give you the volume you need. Port it (you can buy ready made port tubes I a variety of sizes) and could work well.