Bill Fitzmaurice

[quote name='Mr. Foxen' post='760362' date='Feb 28 2010, 08:22 PM']Fairly sure Wayne is going to be the next Alex Claber, so be afraid of the competition. The 5 or 6 fearful threads are fairly interesting reading. They do end up looking a lot like 'The Big One'. Critical analysis of post please?[/quote]The resemblance between Greenboy's and Alex's cabs is far more than cosmetic. Both buck the standards of cabs from the usual suspects in that they adhere to rather than ignore valid acoustical engineering tenets.

[quote name='waynepunkdude' post='760175' date='Feb 28 2010, 04:27 PM']Cheers mate, I'm a little unsure what all of that means if I'm honest.[/quote] And that's why you should not consider designing your own cab, or even choosing your own drivers for that matter. It's far more involved than it appears. For a beginner this is probably your best route, albeit a long one: [url="http://www.talkbass.com/wiki/index.php/Fearful"]http://www.talkbass.com/wiki/index.php/Fearful[/url]

[quote name='Ancient Mariner' post='758904' date='Feb 27 2010, 05:02 AM']I'm trying to use winISD for a speaker not listed in the database. There are some required parameters that I cannot find out for the speaker (a celestion BL12 100) and the program keeps locking up. Any ideas what I can do? Thanks[/quote]Let the program calculate them for you. Only enter Vas, Qes, Qms, Fs, Sd, Re, Xmax, Le, Pe. It will take care of the rest.

[quote name='tom skool' post='757243' date='Feb 25 2010, 11:27 AM']I do have a splitter box ( wired for either series or paralell) Could i use that somehow? have both cabs plug into the box and then run a lead from the box to the amp?[/quote] That should work fine. You could also try it with the cabs in series into the 16 ohm tap, you never know. Cabs in series tend not to work all that well, but it's worth a shot.

[quote name='tom skool' post='756829' date='Feb 25 2010, 05:12 AM']hi all I have got an old valve amp which has got one 8ohm output and one 16ohm output. Is there any way i can attach more than one cab for a bit more oomph? I'm guessing putting an 8 ohm cab to the 8ohm out and a 16 ohm cab to the other wouldn't be right for some reason.[/quote] The taps on a valve amp represent the maximum load that should be used with them, the opposite of SS amps. You can daisy chain cabs no problem, just make sure both cabs have the same impedance. A pair of 8 ohm cabs daisy chained is 4 ohms, so run them off the 8 ohm tap. The 16 ohm tap is pretty much of no value, as 16 ohm and higher cabs are no longer to be found.

[quote name='skankdelvar' post='754343' date='Feb 22 2010, 03:39 PM']A ground lift disengages the amps electrical earth.[/quote] Not quite. Amps of that era had no direct chassis connection to ground, as they used a two-wire connection to the mains. To provide noise filtering they connected the chassis to the ground wire via a capacitor. The problem lay in knowing which of the two wires was connected to hot and which was ground, as the plugs and outlets were not polarized. The ground switch toggled the connection through the cap from one wire to the other. When you powered the amp up you listened for noise and switched the ground switch to the quieter position. Of course when in the wrong position the chassis was connected to the hot wire, but since it was via a cap in the .1uF range it didn't get a full 60 Hz signal, just the higher harmonics. If you touched the chassis or anything connected to it, like your bass, and something that was grounded, like a mic, you'd get a benign but unmistakable reminder of why one should not play an instrument whilst bathing. The ground lift switch on modern gear lifts the ground from the signal direct out, not the chassis to mains ground. [quote]I had some work done on it a few years ago so the switch might have been by-passed but I cant be certain. Ill get it checked out[/quote]. If converted to UK power it should have a 3 wire connection, grounding the chassis and eliminating the ground switch. Unfortunately that would lop a few hundred quid off its value to a collector.

[quote name='Musicman69' post='754115' date='Feb 22 2010, 12:46 PM']Hi Folks, This is my old Bassman head, I bought it in 1980 for 50 punts (with cab) Just thought Id put up pics and maybe someone here might know its age. Looks very '60s to me. Any info appreciated.. thanks. John [attachment=43321:Bassman1.gif] [attachment=43324:Bassman2.gif][/quote] Take a look here: [url="http://www.ampwares.com/"]http://www.ampwares.com/[/url] It appears to be a 61-62, and it might be worth about 100 times what you paid for it.

[quote name='AndyMartin' post='752944' date='Feb 21 2010, 11:35 AM']. I would think that thing would have some sort of crossover in it.[/quote] I doubt it. Between using drivers so close to each other in size, placing them on the horizontal plane, having the cab far too small to support acoustic loading of the drivers and not having a driver in there capable of wide dispersion in the mids why would they screw up things by doing one thing right in using a crossover? [quote]Still pointless though. It looks like a promotional gimmick to me.[/quote] Absolutely.

[quote name='Musicman20' post='752834' date='Feb 21 2010, 09:45 AM']I dont really think Tecamp would make a cab that doesnt work..[/quote]And I don't think companies sell 'male enhancement' drugs that don't work either. All the existence of this monstrosity proves is that even a company with reputation for offering well engineered products like Tecamp isn't above offering a POS if the money is right.

[quote name='Ancient Mariner' post='751416' date='Feb 19 2010, 05:17 PM']So tell me - are open cabs a no-no for bass use?[/quote]An absolute no-no.

[quote name='thisnameistaken' post='746689' date='Feb 15 2010, 06:27 PM']The other bands want to use my amp, which is an LH500 into a 1212L.[/quote] Two things you never loan out: Your rig and your girlfriend.

[quote name='Mr.T' post='738013' date='Feb 7 2010, 07:42 AM']Driving home from a gig last night, I was thinking.... If you took a 2x10 cab and made two 1x10 cabs out of it, each being half the size (and having half the port area) of the 2x10 .......would it sound the same?[/quote] Yes.

[quote name='Smash' post='737133' date='Feb 6 2010, 07:56 AM']Hi does anyone know what the deepest sounding 4x10 bass cab is on the market around the 25Kg weight.[/quote] The largest. Low frequency response is directly proportional to cabinet volume.

You can search out old Fenders and what they've been selling for here: [url="http://www.ampwares.com/"]http://www.ampwares.com/[/url] Fender Bassman 100s were decent enough amps, but their speakers were quite horrid.

[quote name='richrips' post='728174' date='Jan 28 2010, 05:13 PM']This is my rig, 2 x BFM jack 12's [url="http://basschat.co.uk/index.php?showtopic=60932&hl="]http://basschat.co.uk/index.php?showtopic=60932&hl=[/url] and an ovation magnum or stingray[/quote] My rig is one J112, loaded with a 2512, so yours is better than mine. You should be able to do stadiums with those cabs, so something in the amp setup is out of whack. Be very sure the cabs aren't out of polarity.

Make sure the EQ isn't the culprit. I get enough output from a 1x12 on one channel of my Superfly, but only using my own EQ presets. The factory presets were all set to less than unity.

[quote name='bumnote' post='726635' date='Jan 27 2010, 01:01 PM']are you saying the orange 2x12 is only as loud as a single 10? can you explain a bit more[/quote] That's a bit off, an isobaric 2x12 will have the same output as a standard 1x12. The second driver allows the cab to be made smaller with no sacrifice in response, but that bit about there being no such thing as a free lunch reigns true to form, so what is sacrificed is output. The same two twelves in a larger cab would go louder.

[quote name='geoffbyrne' post='720101' date='Jan 21 2010, 08:40 AM']I think BFM said recently, that you shouldn't be able to see the back of the speaker if you look through the port(?)!! G.[/quote]Correct. If you can see the cone then midrange waves can exit the port, which you don't want. Aside from that caveat the port can go anywhere.

[quote name='ViVi' post='719671' date='Jan 20 2010, 06:24 PM']Assuming venting the box, will there be any significant difference betwen the Kappalite and BL15-400X?[/quote]The BL-15 400X has specs close enough to use it sealed, but a 3015 vented will have a lot more low frequency capability than the BL-15 400X either sealed or vented. 40 to 45 Hz tuning will give the best result.

[quote name='Mr. Foxen' post='719431' date='Jan 20 2010, 01:50 PM']Is there a spreadsheet or a way of extracting all the T/S characteristic from WinISD into a spreadsheet, so you can sort by the characteristics you are looking for? Cause once you know stuff like Bill says, you still have to look at every driver to spot them.[/quote] There's none I'm aware of. But if you know how to design speakers you also know how to check driver data sheets and wean out unsuitable drivers literally at a glance.

[quote name='ViVi' post='719226' date='Jan 20 2010, 11:37 AM']Hi all, I am reconstructing my “old vintage cabinet” (nice piece of furniture) and would like to replace the driver. I went through this forum and the best option seems to be Eminence KAPPALITE 3015 or Celestion BL15-300X/BL15-400X. The cabinet is sealed, approx 160 litres and the intention is to use it standalone. I run it through WinISD and it seems that the Kappalite has more midrange response. Will it lead to more clarity? The Celestion BL15-300X seems to be half price of the Kappalite. Will the difference in sound be important or negligible? Many thanks for opinions ViVi[/quote] Neither are well suited to sealed alignments, which typically require a driver Qts higher than .50 and EBP less than 75. WinISD does not predict midrange, it's only accurate up to roughly 200 Hz.

[quote name='goingdownslow' post='717917' date='Jan 19 2010, 09:59 AM']Could this speaker cable be referred to as being coaxial? [url="http://www.canford.co.uk/Products/33-250_CANFORD-HPS-CABLE"]http://www.canford.co.uk/Products/33-250_CANFORD-HPS-CABLE[/url][/quote]It is speaker cable, but IMO not a good choice. Signal loss in speaker cable is through capacitance, and the capacitance of a coax cable is much higher than side by side conductors. The reason for using coax cable is that the shield minimizes noise pickup in instrument cables, speaker cables are immune to this sort of noise pickup.

[quote name='Sumbabba' post='717586' date='Jan 19 2010, 05:58 AM']Hi! Anyone know where in London I can buy a coaxial speaker cable for my lovely new Warwick Hellborg rig?[/quote] Speaker cables aren't coaxial, instrument cables are.

[quote name='Mr. Foxen' post='714033' date='Jan 15 2010, 12:14 PM']What about them? There are factors other than driver diameter at play. They don't sound good because there are 10s and 12s,, they sound good because they are designed taking all the factors into account (or at least getting them right inadvertently).[/quote] [quote]I asked TC about their cab matching, and they said all their artists bar a few chose the 210/212 because it just works. They designed them to work how they do[/quote] I seriously doubt that. They look to be reasonably well designed and constructed, but no more so than cabs from a few dozen other companies building bass reflex cabs loaded with Eminence drivers. There is one fact of audio physics that's never mentioned by any manufacturer: virtually any two cabs together will sound better than either alone. So while the TC 210s and 212s might sound OK together so will most of the 210s and 212s from any other manufacturer. The pertinent question is whether paired TC 210s or 212s would sound better than one of each. That one can only determine by trying all three permutations side by side. On a side topic the TC 2x cabs do place the drivers vertically, and that is infinitely better than side by side, so that much they got right. But they have a traditional 4x10 in the line up as well, so they're not above sacrificing engineering concerns to the gods of marketing.

[quote name='Al Heeley' post='713969' date='Jan 15 2010, 11:25 AM']If thats the case then why do all the major companies sell same impedance 410's, 210's and 115's, designed to be used in pairs?[/quote]Your question is its own answer. Cab companies build and promote what they think will sell, and the vast majority of players buy their cabs based not upon the engineering within but rather on how they look and who uses them. Mixing drivers to cover the same bandwidth is not good engineering, but it is successful marketing. If you must succumb to the lures of that marketing a 1x15 and 2x10 are a reasonably good match. A 1x15 and 4x10 isn't. [quote]Some cabs are made so that they can be mixed, with time aligned, phase coherant and excursion matched cabs, but probably not many.[/quote]I'm not aware of any. If any of the usual sources possessed the technical know-how to do that you can rest assured that they wouldn't keep it a secret. AccuGroove tries to make it seem that way in their ad copy, but their level of technical incompetence was tellingly revealed in the AccuSwitch debacle. The only significant engineering that I'm aware of where mixed cabs is concerned lies in making the footprints the same for stacking. More than a few 1x15 and 4x10 cabs share not only the same footprint but the exact same cabinet save the number of holes in the baffle. That should set off alarm bells, but curiously it doesn't. The stacking of the two looks very pretty, so it sells.