stevebasshead Posted May 7, 2015 Share Posted May 7, 2015 I've got an old Marshall 1x15 cab (late 70's I think) and I'm toying with getting a new front baffle made up and fitting either 4x10's or (if I can squeeze them in) 4x12's. I know WinISD can be used to design a cab for the specs of a given speaker but is there any software that can do the reverse? As in, I know my cab's internal dimensions - how do I choose an appropriate set of drivers for it? Quote Link to comment Share on other sites More sharing options...
Balcro Posted May 8, 2015 Share Posted May 8, 2015 (edited) Hi stevebasshead, Once you've fitted the new empty front baffle and secured it against battens or whatever, what (height x width) dimensions remain? Can you still fit two 10" speakers side by side and still leave room for some wood between them? If that's possible, then divide the internal volume by 2 or 4. That gives you the possibilities for volume per drive unit. Some, not all, loudspeaker manufacturers publish data showing a suitable volume for their speaker drive units on the product page. Check their web-sites. For others you'll have take the t/s parameters and run them through winISD to see if the volume is appropriate. Also:- 1. What are you trying to achieve? 2. What is the existing internal volume? 3. Why change from a 15" drive unit? Balcro. Edited May 8, 2015 by Balcro Quote Link to comment Share on other sites More sharing options...
stevebasshead Posted May 9, 2015 Author Share Posted May 9, 2015 Hi Balcro, The baffle does indeed fit against battens and the baffle size within the battens is 63.5cm High (25") x 65cm Wide (25.5"). 4 x 10's will definitely fit but the within-batten area is just about enough for 12's. I think it will leave enough wood between the cutouts for structural strength. To answer your questions in more detail: 1. I want to move more air/achieve greater volume through a greater surface area of speaker (1x15 = 176 sq in -vs- 4x10 = 314 sq in -vs- 4x12 sq in) all things being equal in the speaker sensitivity stakes of course. I love my Marshall Super Bass, the sound I get from it is wonderful but the new band I'm in doesn't put bass through their PA (it distorts) and I'm running out of headroom on the Marshall. I'm looking to get more volume without driving the Marshall too much into distortion. I like a bit of grind but without PA support I'm running it too hard to get sufficient volume and having to sacrifice headroom and that sound doesn't work on all our songs. 2. 5.36 cu ft 3. As 1 Cheers, Steve. Quote Link to comment Share on other sites More sharing options...
PlungerModerno Posted May 9, 2015 Share Posted May 9, 2015 Have you considered a 3 or 2 way split? It could be cost prohibitive, depending on the crossover and drivers used, but it could provide the huge power handling boost you're looking for. Here are some plans for that kind of thing: [url="http://greenboy.us/fEARful/"]http://greenboy.us/fEARful/[/url] Of course the problem with this is you've already got 5 sides of the cab completed. Quote Link to comment Share on other sites More sharing options...
stevebasshead Posted May 9, 2015 Author Share Posted May 9, 2015 I appreciate the idea, thanks, but on balance I'm aiming to keep it simple and relatively low cost. I suspect I'll have enough on my hands finding speakers that will work in my cab (a very shallow, traditional old Marshall design) and having to factor in crossovers might fry my man brain... Quote Link to comment Share on other sites More sharing options...
PlungerModerno Posted May 10, 2015 Share Posted May 10, 2015 Well as long as it's safe (I'm talking electrically) and can be returned to stock (I assume you'll be keeping original components with it) it should be an interesting, and hopefully successful project. I agree a crossover is an expensive idea, probably more suited to deeper cabs with more internal volume (and used with serious excursion sub drivers) for the massive power handling the 2 and 3 way designs are known for allowing. You should still be able to get a pretty noticeable increase in volume by adding more speaker area, provided the drivers are of greater or equal efficiency! Quote Link to comment Share on other sites More sharing options...
JTUK Posted May 10, 2015 Share Posted May 10, 2015 New speakers are going to cost you a minimum of £200, I'd say...plus wood etc, plus aggro.. Could you not buy a decent 410 with that and the money you'd get for the 115..? Not sure the cab will fit 4x12's in any sense, tbh Quote Link to comment Share on other sites More sharing options...
Balcro Posted May 10, 2015 Share Posted May 10, 2015 (edited) Hello stevebasshead, I've had a look at a few 10" options and there is no shortage of speakers to fit in as a 4x10. Some are pretty weak and others look really great with lots of power handling. Also don't be surprised by a difference in tonal balance. However, as jtuk says , you have to look at the cost. Four new speakers (in general) can cost from £200 to over £325. By the way, what speaker is fitted in the box at the moment? Balcro. Edited May 10, 2015 by Balcro Quote Link to comment Share on other sites More sharing options...
tauzero Posted May 10, 2015 Share Posted May 10, 2015 [quote name='stevebasshead' timestamp='1431176264' post='2768508'] 1. I want to move more air/achieve greater volume through a greater surface area of speaker (1x15 = 176 sq in -vs- 4x10 = 314 sq in -vs- 4x12 sq in) all things being equal in the speaker sensitivity stakes of course. [/quote] It's not just the area of the cone that counts, it's how far the cone moves. Quote Link to comment Share on other sites More sharing options...
dincz Posted May 10, 2015 Share Posted May 10, 2015 [quote name='tauzero' timestamp='1431284542' post='2769641'] It's not just the area of the cone that counts, it's how far the cone moves. [/quote] Exactly. Think in cubic inches rather than square inches. Quote Link to comment Share on other sites More sharing options...
PlungerModerno Posted May 11, 2015 Share Posted May 11, 2015 +1 to the suggestions above - the choice of drivers is all about their efficiency at turning Watts in into sound energy out, and at what frequencies they can do that job. The speaker area is only part of it. Everything from port design, internal cab volume, driver excursion & frequency response are all vitally important at different frequencies. A great full range driver may make a mediocre sub-woofer and a great sub driver will likely do poorly at anything else. To get an increase in output volume from the cab (from the same energy in) requires increasing it's efficiency. This can be done by replacing the driver with a similar driver that's more efficient or another arrangement of drivers that overall is more efficient. Depending on the specific details this may be challenging. A more achievable goal from my understanding of the situation at hand is to seek increased power handling. Increase the efficiency somewhat and increase the power handling by quite a lot (for example, replace a 250W RMS 15" driver with 3 200W RMS 12" drivers) and you should be on the train to loudersville. Only thing is, you need a surprising jump in actual sound energy to get a noticeable increase in volume. I can't explain fully it in simple terms but my understanding is that to get a doubling of perceived volume you need to put 10 times the sound energy out. Here's a link that could be useful: [url="http://www.sengpielaudio.com/calculator-levelchange.htm"]http://www.sengpielaudio.com/calculator-levelchange.htm[/url] Quote Link to comment Share on other sites More sharing options...
stevebasshead Posted May 11, 2015 Author Share Posted May 11, 2015 (edited) [quote name='JTUK' timestamp='1431259084' post='2769287'] New speakers are going to cost you a minimum of £200, I'd say...plus wood etc, plus aggro.. Could you not buy a decent 410 with that and the money you'd get for the 115..? Not sure the cab will fit 4x12's in any sense, tbh [/quote]Yep, quite possibly and it's a route I'm also investigating, but still toying with the idea of converting the 1x15 as another option. [quote name='Balcro' timestamp='1431266247' post='2769401'] Hello stevebasshead, I've had a look at a few 10" options and there is no shortage of speakers to fit in as a 4x10. Some are pretty weak and others look really great with lots of power handling. Also don't be surprised by a difference in tonal balance. However, as jtuk says , you have to look at the cost. Four new speakers (in general) can cost from £200 to over £325. By the way, what speaker is fitted in the box at the moment? Balcro. [/quote]Thanks Balcro. The original 15" (a Celestion Powercell) was coming away from the surround when I got the cab. I couldn't find anyone to recone it and so I'd (embarrasingly) repaired it with superglue instead of something more compliant. It lasted fine but another area of the cone started to part company with the surround so I took the speaker out and replaced with a Celestion Truvox 1525 (300w 8ohm) at the suggestion of Blue Aran. [quote name='tauzero' timestamp='1431284542' post='2769641'] It's not just the area of the cone that counts, it's how far the cone moves. [/quote] True indeed [quote name='PlungerModerno' timestamp='1431330651' post='2769937'] +1 to the suggestions above - the choice of drivers is all about their efficiency at turning Watts in into sound energy out, and at what frequencies they can do that job. The speaker area is only part of it. Everything from port design, internal cab volume, driver excursion & frequency response are all vitally important at different frequencies. A great full range driver may make a mediocre sub-woofer and a great sub driver will likely do poorly at anything else. To get an increase in output volume from the cab (from the same energy in) requires increasing it's efficiency. This can be done by replacing the driver with a similar driver that's more efficient or another arrangement of drivers that overall is more efficient. Depending on the specific details this may be challenging. A more achievable goal from my understanding of the situation at hand is to seek increased power handling. Increase the efficiency somewhat and increase the power handling by quite a lot (for example, replace a 250W RMS 15" driver with 3 200W RMS 12" drivers) and you should be on the train to loudersville. Only thing is, you need a surprising jump in actual sound energy to get a noticeable increase in volume. I can't explain fully it in simple terms but my understanding is that to get a doubling of perceived volume you need to put 10 times the sound energy out. Here's a link that could be useful: [url="http://www.sengpielaudio.com/calculator-levelchange.htm"]http://www.sengpiela...levelchange.htm[/url] [/quote]I've a good understanding of speaker sensitivities and excursions and other tech stuff etc. etc. but that site was too much for my man brain lol!...But yes, I do understand the basic point you're making about the choices of speakers. It's pretty much why I started this thread, I was hoping someone would know of a "WinISD in reverse" to help me choose the appropriate speakers for the existing cab dimensions rather than designing a cab around a given speaker compliment. But it seems the only real way to do it is to do as Balcro suggested, measure my cab and feed that into WinISD and compare to speakers available on the market for ones that match closest. I've got a lead on a Marshall VBA400 and VBC412 going for a quite reasonable price...more than I want to pay for converting my cab but too tempting to not at least go and have a play...so for now I might put the conversion idea on hold until I've had a chance to go and see the beasts... So thanks all, for now, much appreciate the advice Edited May 11, 2015 by stevebasshead Quote Link to comment Share on other sites More sharing options...
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