Bill Fitzmaurice

[quote name='JTUK' timestamp='1395223111' post='2399818'] ok..go careful then. If they are in good working order, then £50 sounds ok, but I am not sure many produced 12" at 300watts 20 years with that manufacturing pressed plate. [/quote]A stamped frame doesn't indicate all that much, though from the picture it's not possible to be certain whether they're stamped or cast. The cast EV SRO from the 1960s looked quite similar. The lack of a vented pole piece is far more telling, but that still doesn't reveal potential power handling. Not that power handling in and of itself matters, T/S specs are what one needs to determine the driver suitability.

Google it, they're a major driver and speaker manufacturer in Italy.

Search locally for something like this: http://www.homedepot.com/p/TrafficMASTER-Black-24-in-x-36-in-Anti-Fatigue-Vinyl-Foam-Commercial-Mat-60-571-0900-20000300/202015909

[quote name='andrewrx7' timestamp='1394702213' post='2394103'] does this linear array set up all go wrong when you add guitar amps into the mix? Do you end up with the comb filtering effect again? [/quote]You don't, the guitar amps do.

Headphones have very flat response and a wide bandwidth, bass cabs don't. I wouldn't judge an amp based on what you hear through phones.

[quote name='andrewrx7' timestamp='1394640986' post='2393619'] On a cab that quotes a frequency response from 60Hz, presumably porting would not offer much of an advantage then, assuming there is little effect from the ports from 80Hz upwards (Bill's post #8)? As ever, interesting reading, and thanks to Bill for sharing his knowledge. Does he ever sleep?? [/quote]Most ported cabs are tuned to 45-50Hz, and the bulk of their output there is from the port. Another factor is cone excursion, which is at a minimum at the tuning frequency. That means a ported cab has even more of an advantage over sealed in the low end in terms of maximum output, as the sealed will reach its excursion limits far sooner. The difference can be 10dB, which is the equavalent of 1000 watts versus 100 watts. [quote]Does he ever sleep??[/quote]I'm five hours behind you. Besides, I cruise the web just as most of you do, while at work. For me work is at my computer in my livingroom, and I don't have to worry about the boss peeking over my shoulder to see what I'm up to.

[quote name='charic' timestamp='1394632727' post='2393525'] I thought that if a cab was rear ported and near a wall it was different? I'm probably wrong though [/quote]Only if it's within an inch or two of the wall. [quote]I always thought front ports had more "throw" but I'm hardly technical minded [/quote]Look up the definition of 'omnidirectional'. Not only is port output omnidirectional, so is that from the cones up to about 200Hz.

[quote name='andrewrx7' timestamp='1394629644' post='2393461'] Does porting actually do much, or is it 90% hype?[/quote]A ported cab can deliver on average 6dB more output in the lows than sealed.That's the equivalent of doubling the cab count or quadrupling the power. But that's only in the lows, and it assumes a properly configured ported cab. There's no difference above roughly 80Hz. [quote]Does it matter if the ports are forward or rear facing? [/quote]No. Port output is omnidirectional.

[quote name='6v6' timestamp='1394617815' post='2393287'] Interesting! I was under the (evidently misguided?) impression that for bass cabs you had to avoid them being too shallow, so as to avoid reflections from the back of the cab interfering with the response of the driver?[/quote]Reflections from the back of the cab are controlled by lining the cab with damping. Or they're supposed to be, some manufacturers have been known to leave it out as a cost cutting measure. [quote]I have an open back 4x10 guitar cab which is only about 9inches deep, could I seal the back of it and put a new baffle in it with, say, a 15" driver? Edit: Yes I know I'd need to model the cab wrt volume and the driver specs.. [/quote]You could. The Eminence Beta 15 specs well for a sealed cab, it's similar to those used by Ampeg.

[quote name='Musky' timestamp='1394583704' post='2393116'] Trace did a 3x12 guitar cab with the speakers all angled in different directions. Needless to say it never caught on. [/quote]It was doomed because it didn't come from the usual cookie cutter mold. Trouble is, if you only try cookies from the usual mold you might never taste biscotti.

The depth per se doesn't make much of a difference, but the volume of the enclosure determines how the speaker will perform. Too small and the low end will be choked off while the midbass will be boomy.

[quote name='andrewrx7' timestamp='1394540612' post='2392387'] Crikey, my lunch break isn't long enough to read all that link! Thanks for that, I'll see how much of it I understand! [/quote]Scroll down to [i]What if We Try a Different Type of Horizontal Array?[/i] to get to the meat of it. [quote]Sunn Beta guitar combo had cross-firing speakers[/quote]Cross-firing works. It's never been successful in the marketplace because 'it looks funny'. With bass cabs cross-firing reduces the internal volume of the cab, and that reduces bass response and output. Bass also has far less issues with beaming than guitar, so cross-firing isn't as beneficial as with guitar.

[quote name='andrewrx7' timestamp='1394528295' post='2392142'] Would not having several speakers slightly angled provide a more even sound to an audience? [/quote]It won't. This explains why. It's about PA, but the physics is the same: http://www.gtaust.com/filter/05/07.shtml The number one enemy of good horizontal dispersion is horizontally placed drivers. The number one reason why drivers are placed horizontally is 'that's how we've always done it'.

[quote name='Ghost_Bass' timestamp='1394451692' post='2391390'] Fender Rumble cabs (1x12" and 2x8") are only 250W RMS, don't mind the "programme" numbers, only the "continuous power" ratings. [/quote]The wattage ratings are fairly meaningless, whichever you look at. Output is limited by the total driver displacement. A pair of eights that you might find in a Rumble have perhaps 150cc of displacement. One ten in that price range will have around 140cc, one twelve around 230cc.

[quote name='LukeFRC' timestamp='1392833657' post='2373287'] How long before we see a spate of cabs all looking like your simplexx range I wonder... [/quote]What makes them different is what's on the inside anyway.

[quote name='Torben Hedstrøm' timestamp='1392819561' post='2373062'] But if companies like MarkBass, Genz Benz (R.I.P), SWR (R.I.P), EBS, Glockenklang etc. Don't have engineers doing actual optimizations for both cabs and amps, I would be very surprised !. [/quote]I wouldn't. I could tell you of a number of companies who have no engineers, because I've done designs for them. I could, but I won't, because that would violate the first thing that they make you sign before embarking on a project, which is a non-disclosure agreement. More than a few companies would be severely embarrased if it was known that they don't do their own R&D. Some don't even hire outside engineers. You'd be amazed at how many companies arrive at their designs by simply copying others. You'd also be shocked to know how many don't build their own cabs. There are a number of independent cabinet building companies who build cabs for many companies all under the same roof.

It won't bother anything, but it won't sound good, mainly because of the speakers. Guitar speakers are made to distort at low output levels, bass speakers are made not to distort.

[quote name='Torben Hedstrøm' timestamp='1392805588' post='2372866'] Don't get me wrong, I am sure that their products are excellent, but they are measuring themselves against corporations with million dollar R&D budgets, [/quote]When those comparisons are made it's the corporations with 'million dollar R&D budgets' that come up short. First off, no bass cab manufacturer spends that kind of money on R&D. For that matter, a very small percentage of their budget is devoted to R&D with respect to technical improvements. Most of it is spent on market research for what really sells cabs, which isn't how they sound. It's how they look.

[quote name='famine43' timestamp='1392803163' post='2372829'] I've done some research and am currently torn between the Eminence Beta 10A or the Celestion BL10-200X. [/quote]How did they compare to each other after you modeled them in your cab with speaker modeling software and you compared the high frequency response on the manufacturer driver data sheets?

[quote name='bass2345' timestamp='1392000774' post='2363476'] What do you think? Does it matter if I play an open D string instead of fifth fret on the A string, for example? [/quote]Yes. The fundamental to harmonic intensity ratio is greater with the longer string length. But from a playing standpoint I don't consider that over the ease of fingering. I take the shortest route from note to note. That means I may play the same note on two different strings during a song if that's what results in the least amount of hand movement. The difference between the sound of the two is apparent when playing alone, but in the context of with a band it gets buried in the mix.

[quote name='leosep' timestamp='1391781745' post='2361213'] Thanks bill, yes i know drivers and cabs must be matched, using speaker modeling software, i have WinISD. Just wanted to know if these spekers that i already have could do the job, at least for a practice cab. I think i need to buy new ones then. I dont have the cabs done yet. [/quote]If you already have them you've got nothing to lose, and it gives you the opportunity to experiment without making a huge investment.

This is one of those "if you have to ask" scenarios. Drivers and cabs must be matched, using speaker modeling software, like WinISD Alpha Pro, which will accurately predict the low frequency response and maximum output, while results above 200Hz can be seen on the driver data sheet SPL charts. If you had the necessary skills to design your own cab, or to driver swap with an existing cab, you wouldn't be asking this question, and acquiring these skills literally takes years. If you're just learning start with tested designs using the drivers recommended for them for the first few builds; when you really start to understand how speakers work then you can start experimenting on your own. As to those drivers, the first and last I'd avoid because you don't get the quality you need at those prices. The second looks OK, but the mids are weak, so it would best be used in a three way design. It's more of a PA driver than electric bass.

[quote name='Roland Rock' timestamp='1391204312' post='2354662'] Would playing them too cold mean lack of optimum performance, or actual risk of damage? [/quote]I've had raw drivers that I left in my workshop overnight at 40F measure nearly an octave above spec. If you were to play though them in that state and try to get them sounding normal you might damage them. It's like a car, you don't want to start it cold and go to cruising speed before the oil has come up to temp. Not that you know what cold is, a Scotsman might.

[quote name='Marvin' timestamp='1391180164' post='2354244'] I'd like to keep the character of the cab, it's got a lovely amount of of low end. [/quote]You'd have to match the T/S specs and response of the drivers, and Ampeg won't give you that information, nor will Eminence as it's a proprietary OEM driver. I can tell you that the OEM drivers weigh only 6.7 pounds each, so you'd save very little, if any, weight with neos.

[quote name='NancyJohnson' timestamp='1391188361' post='2354424'] I suppose I have concerns over speaker degradation and bring the cabinets from a cold environment into a warm/moistish one. [/quote]That concern is valid. Cold speakers don't work to spec, and it takes a long time for them to warm, as the insulation inside them works like a cooler. So long as they're stored above freezing you're OK, but I wouldn't store them where it goes below freezing unless they'll have a few hours to warm up before using them.