Bill Fitzmaurice

[quote name='Marcus' post='263920' date='Aug 17 2008, 07:43 AM']Hi Guys, I think one of my 10' drivers is on it's way (centre is detatched from the paper cone) I need some advice on a possible repair..... (is it possible to glue it ? if so what type of glue)[/quote] Superglue. Put a bead around the joint, then spray it with cure accelerator.

[quote name='Sean.Robinson' post='263962' date='Aug 17 2008, 09:43 AM']Ok thanks for all your help, i have shifted the topic onto eden as you've advised ([url="http://www.eden-electronics.com/forum/topic.asp?TOPIC_ID=13332"]http://www.eden-electronics.com/forum/topi...?TOPIC_ID=13332[/url])[/quote] Changing to a toroid power transformer alone would have an imperceptable effect on hum level. A complete refurbishing of the power supply, incuding major upgrading of the filter caps, would be required. Basically what you want to do is to take a Ford and bring it up to Mercedes specs. While not impossible to achieve, you'd find it a far simpler matter to sell the Ford and buy a Mercedes.

[quote name='Sean.Robinson' post='263790' date='Aug 16 2008, 06:15 PM']Hi, not something ive really thought about correcting until now as im sure its normal, but my amp hums/hisses a little when nothing is plugged in and it is just turned on though nothing is plugged in or been played. Ive heard it on all amps so im sure its normal, but is there any way to reduce or even get rid of it all together, such as using balanced cables, or by some mods to the amp head?[/quote] Cables can't very well be the issue if the amp behaves badly when none are plugged into it. All amps make noise, how much is a matter of how well engineered they are, or are not, as the case may be. Reducing noise is possible, but not easy, a usual prerequisite to doing so being a EE degree.

[quote name='Protium' post='256462' date='Aug 6 2008, 11:50 AM']the shape of the waveform does not matter.[/quote] Not a whit. BTW, what happens when you push a driver past xmax? It creates clipped waveforms, in exactly the same fashion as do over-driven amps, or stomp-boxes.

[quote name='Protium' post='256141' date='Aug 6 2008, 07:05 AM']I am still going by the argument that the speaker does not care what shape the waveform is, as long as the mechanical limit (Xmax) of the speaker is not exceeded.[/quote] Exceeding xmax doesn't bother anything, it just makes for a dirty/compressed tone. Guitar players get their tone by exceeding xmax, and being able to do so in the midrange is why guitar drivers have small xmax values. Exceeding xlim OTOH has disastrous consequences.

[quote name='Welshbassist' post='253794' date='Aug 3 2008, 12:11 PM']So if it's okay, what was the point of the whole incredibly long BS explanation then? That just made things too complicated and hard to understand. I love my Epi UL, but they just went a little crazy there.[/quote]What it came down to is that they were trying to make it seem that if one wanted the best result from their cabs, which sell well, one needed to use one their amps, which don't. They got called out on it and tried to retract their statement without admitting that it was a load of BS to begin with. The resulting 'clarification' contained even more BS than the original statement. The incident left a very sour taste, rightfully so IMO.

[quote name='molan' post='253445' date='Aug 2 2008, 01:53 PM']Sounds like fun, might make a great reggae cab [/quote] Perhaps, if reloaded with modern drivers. Those used in the original weren't much, but in 1968 what was? Also, their first generation SS circuits were powerful but unusably noisy if you set the treble knob above 12:00, and even full off the hiss was still quite obvious.

[quote name='alexclaber' post='252092' date='Jul 31 2008, 10:10 AM']Though with modern technology it would only take two 10" speakers voice coils to dissipate that heat[/quote]It wasn't the heat, it was the excursion. The original 1969 SVT drivers were guitar drivers, with perhaps 1mm xmax. It took two of the 8x10 cabs to handle the 300 watt head clean. Longer xmax drivers were introduced in the early 70s and since then only one cab was required. [quote]On alt.guitar.amps there was recently mention of "hang time" in relation to driving speakers, the idea being that with a square wave into a woofer it would be possible to have the voice coil stationary for most of each half cycle, and that excessive power would be dissipated in the relatively low resistive load (?) of the stationary voice coil.[/quote]Complete utter total piffel. That never happens. Said post was not made by a competant transducer engineer. Railroad engineer, maybe.

[quote name='Fraktal' post='252047' date='Jul 31 2008, 09:06 AM']Thanks a lot for your insight, Alex, always good to learn new things. Unfortunately I think Im having a hard time to understand your response, do you have any graphics? Maybe it would be easier with a picture or 2...[/quote] Graphics in this case is a culprit. The 'underpowering' nuts show a picture of a square wave as it appears on an oscilloscope to bolster their case. Musical waveforms of that sort do not exist. A clipped musical waveform consists of a normal sine wave at the fundamental to which has been added an abnormally high level of harmonics. Those harmonics can result in overpowering of tweeters, and in extreme cases midranges. They have absolutely no effect upon woofers.

[quote name='Mr. Foxen' post='251309' date='Jul 30 2008, 08:28 AM']run your amp into clipping and put a square wave dc current into your speakers[/quote]Said 'square wave DC current' falls into the same category as Medusa, Chimera, Unicorns, Hercules and Fiscal Responsibility in Government.

[quote name='waynepunkdude' post='248875' date='Jul 27 2008, 07:50 AM']I played with a band a few weeks back, the bass player had the same cab as me (Ashdown 4x10) so we decided instead of stacking them we set one up on each side of the stage and it sounded amazing, not much help but I'm never much help.[/quote] There probably were some places where it sounded amazing, but they would have been exceeded by those where it sounded worse than if stacked. A visual representation of why using spread low frequency sources is a bad idea found here: [url="http://www.falstad.com/wavebox/"]http://www.falstad.com/wavebox/[/url] BTW, the same destructive interference that occurs at low frequencies with cabs placed more than a few feet apart occurs in the mids and highs when drivers within a cab are horizontally mounted.

[quote name='bass_ferret' post='248504' date='Jul 26 2008, 12:03 PM']But is wide dispersion always desirable?[/quote]Dispersion is not a constant, it varies with frequency. No matter how a cab is oriented low frequency dispersion (roughly 400 Hz and below) is 360 degrees. Going higher in frequency the dispersion angle narrows as frequency goes up, so the cab sounds different depending where you're standing. The wider the dispersion angle is maintained with increasing frequency the more uniform it sounds within the listening area.

[quote name='bass_ferret' post='248346' date='Jul 26 2008, 06:55 AM'] Your'e a glutton for punishment The fallacy that the "bass" cab goes on the bottom and the "treble" cab goes on the top when they are both reproducing the same signal (unless they are actually being bi-amped) is an extension of the fallacy that a stack has to have 15's and 10's.[/quote] It's not a matter of both reproducing the same signal, it's a matter of dispersion. Even if the 15s and 10s have exactly the same frequency response chances are the tens will have wider dispersion in the midrange, so better to have them on top where that dispersion can be put to good use. [quote]The cabs on their side bit arranges the drivers vertically. This is because of another bit of science that may or not affect the sound (in your opinion) etc etc. Horizontal arrangement of drivers causes something called comb filtering or lobe filtering, where phase cancellation causes peaks and troughs in SPL depending on your position relative to the cabs.[/quote]The existence of comb-filtering isn't a matter for debate, it's a phenomena well known for at least 75 years. Those who deny its effect should also consider memberships in the Flat Earth Society. OTOH elimination of combing is not the overriding reason for vertically aligning drivers. Expanding the width of the horizontal plane of dispersion, as Alex explains above, is. Second to that is the narrowing of the vertical dispersion pattern, placing more sound in the audience, unless you're playing to dust mites on the floor and bats in the belfry. As a benefit of vertical alignment the elimination of combing comes in third.

[quote name='labougie' post='247261' date='Jul 24 2008, 03:47 PM']I'm coming back to bass-playing after many years away from it. I've got a pair of 1225e Celestions (300w, fs 61Hz, Xmax 3.3mm, XMech 12mm). Would I be banging my head against a brick wall trying to build two 1x12 cabs with these, driving them with maybe 250 watts of Peavey and expecting to get enough bottom end to do small pub gigs with?[/quote]You won't knock walls down but they'll do for a small club. 3.3mm xmax is about average for OEM drivers. Do the cabs right and you'll likely be better of than with commercial 1x12s.

[quote name='stevie' post='245674' date='Jul 22 2008, 03:52 PM']The SRX series is shown using the 2226H on the current JBL Pro website. [url="http://www.jblpro.com/pages/mi/srx/srx.htm"]http://www.jblpro.com/pages/mi/srx/srx.htm[/url][/quote] Check the publication date on that obsolete link. As opposed to this one: [url="http://www2.jblpro.com/catalog/general/ProductFamily.aspx?FId=10&MID=3"]http://www2.jblpro.com/catalog/general/Pro...Id=10&MID=3[/url] Also consider getting a life.

[quote name='alexclaber' post='245200' date='Jul 22 2008, 06:09 AM']curved sided cone, and concentric ribbing around the cone, all of which allow the cone to flex Alex[/quote]Those refinements are intended to make the cone stiffer, to reduce flex and along with it break-up. So doing allows a lighter cone material, and the benefits of same, which includes a higher response. The ribbing is similar in look, but not function, to Altec bi-flex drivers, which incorporated a surround in the cone that allowed more independance between a stiffer/lighter inner cone and softer/heavier outer cone.

[quote name='redstriper' post='244949' date='Jul 21 2008, 06:44 PM']would like to hear from people who have actually heard all 3 in the flesh[/quote] I've heard those and perhaps 100 more fifteens over a 40 year span. IMO for a single driver cab the 3015 is unexcelled. The 3015LF is even better in extension and power handling but should be used along with a midrange driver, although for raggae and dub one might get along without it.

[quote name='stevie' post='244815' date='Jul 21 2008, 04:12 PM']The off-axis performance of a 2226H is a function of its diameter. It is no better or worse (and its response doesn’t drop off any faster) than any other 15 inch driver.[/quote]Off-axis response as a function of cone diameter assumes that the cone operates as a single pistonic radiator. In the case of extended range musical instrument and pro-sound drivers the dome acts as an independant midrange radiator, and the response both on and off-axis is not a function of cone diameter alone. [quote]JBL uses the 2226 in its current SR-X series[/quote]The SRX715 and SRX725 have used the 2256 neo magnet woofer since 2004.

[quote name='stevie' post='244655' date='Jul 21 2008, 01:19 PM']The JBL 2226H... good quality extended midrange.[/quote] On-axis plots may give that indication, but off-axis response is what matters. At 45 degrees off-axis the 2226 drops like a stone above 1kHz, and is down (and out as it were) by 16dB at 1.5kHz. [quote]I checked, and the 2226H is actually a current model.[/quote]Still in production, but hardly current. The telling point is that JBL no longer uses it in their current pro-sound cabinet offerings. JBLs top of the line drivers have been neo for nigh on a decade, but they are not sold as separate components.

[quote name='Hamster' post='242135' date='Jul 17 2008, 03:48 PM']A tweeter is just a small kind of loudspeaker designed to reproduce higher frequencies. It's personal preference really as to what sound you want. Generally for a brighter sound you need tweeters, for a dub reggae sound you don't. A 12" bass driver won't be that good for anything above 5kHz. Hamster[/quote]A 12 isn't much good above 2kHz, irrespective of what's claimed, as those claims are for on-axis response. Move off-axis by two feet and the high end disappears. The trouble is that tweeters don't go to 2kHz. Most don't go below 4kHz. What you end up with is no mids and a lot of hiss. What works best with a 12 is a midrange that covers up to 5-6kHz or so with uniform off-axis response. But it's a more expensive option, so very few manufacturers offer it.

[quote name='beerdragon' post='241853' date='Jul 17 2008, 11:11 AM']as i said i haven't a clue about this, neither its seems does our keyboard player.[/quote] That's usually a good reason to leave well enough alone. Newbies, speakers and soldering irons are a combination that can lead to blown amps.

[quote name='alexclaber' post='241763' date='Jul 17 2008, 09:01 AM']The 2226H looks more comparable to a 3015LF (though has less Xmax and weighs a lot more) in that the treble extension is very limited and thus really needs a midrange speaker unless you only play dub/reggae. Alex[/quote] +1. As good as the 2226 was when introduced it's day is long over. Consider that even JBL has not used them in their high end products for years. As a standalone driver the 3015 has twice the useable bandwidth, while as a pure woofer the 3015LF at half the weight has twice the displacement limited power input capability. If all you desire is a simple cabinet the horse's mouth can be found at [url="http://www.eminence.com/resources/cabinets.asp"]http://www.eminence.com/resources/cabinets.asp[/url]

[quote name='beerdragon' post='241774' date='Jul 17 2008, 09:21 AM']i was a bit sceptical.[/quote] As well you should be. It's not possible to rewire a 4 ohm 2x10 to 8 ohms. If indeed the meter reading went from 4 to 8 ohms it could only do so if one of the drivers was disconnected. BTW, a meter would not read either 4 or 8 ohms, as it measures the voice coil resistance, not impedance. The DCR measurement is on average .7 the impedance. I assume you took that into consideraton with your results.

[quote name='phatbass787' post='204501' date='May 22 2008, 02:17 PM']Yup good idea, the superfly 48 cab does the same thing it has 2 x 4 ohm inputs, so full power into one little cab! So you can take one cab to the gig![/quote] Perfectly logical, assuming that a 4x10 can actually make use of more than 500 watts. AFAIK none can. Most can't make use of more than 200 watts, so powering them with 500 is more than adequate. The number of cabs of any configuration that can make use of more than 500 watts can probably be counted on one's fingers.

Buy two Neutrik Speakon connectors and the length of 14 ga (2mm) wire you desire and assemble it yourself, no soldering required.