Bill Fitzmaurice

[quote name='Crazykiwi' post='278929' date='Sep 6 2008, 09:11 PM']The Eden forum would have you believe that neo magnets are more susceptible to heat fatigue and have a shorter life.[/quote] Only because they were the last to get on board, and with what appear to be Eminence OEM at that. Now let me guess, do they claim they waited the extra five years so that they could 'get it right' ?. No surprise there, when they still blatently lie about the frequency response of their cabs.

[quote name='Mr. Foxen' post='278816' date='Sep 6 2008, 03:58 PM']Gonna be soon, totally impractical as I have trouble lugging mine around as it is[/quote]A proper bi-amped rig is not larger than others. A well engineered one is smaller. That's because the top cab can be at least 75% smaller than a full range cab as it doesn't have top carry any bass frequencies. Finding a well engineered bi-amp rig is another matter, no one I'm aware of makes one.

[quote name='DaveSetchfield' post='278822' date='Sep 6 2008, 04:12 PM']Are there any problems associated with neodynium magnets, which aren't being spoken about?[/quote]No. They've been used almost exclusively in top of the line touring PA for some ten years now. It's not new technology. [quote]I would have thought that if a way of making cabinets much lighter came along it would be snapped up and introduced by manufacturers across the board, but this hasn't happened, why not?[/quote]It has, in the higher price ranges. Most OEM drivers are lower priced models, and that's not where neo is most beneficial, as the weight savings there are only a few pounds. Neo dominates where the old ceramic magnet models weighed twice and more what the neo versions do.

[quote name='jensenmann' post='278595' date='Sep 6 2008, 09:11 AM']Only exception from that are very modern line array PAs with cardioid subs. They will throw the bass only into the crowd, not on stage. Here you need something bigger than 10" speakers.[/quote] Those venues will have a full complement of monitors, both wedges and sidefills, as well as in-ears in many cases, so Uber cabs aren't required. This side of the pond tens remain the #1 driver size seen on tour w/major acts. The problem venues are those large enough to require PA support but not sensible enough to provide it. But even then four tens vertically aligned are enough to do the job, which is providing adequate output for the stage and the first 50 feet or so of room. If there's no PA to cover beyond that it's the promotors problem, not yours.

[quote name='fretmeister' post='277885' date='Sep 5 2008, 09:49 AM']I had never thought about stacking them 4 in a line though - other than getting them up to ear level, are there any other benefits?[/quote] The dispersion angle on the horizontal plane is wider, so everyone can better hear what you're playing, while the dispersion on the vertical plane is lessened, placing more output in the audience rather than aimed toward the floor and ceiling.

[quote name='david_l_perry' post='277634' date='Sep 5 2008, 05:14 AM']Forgot to add that unfortunately the Omni 10.5 and Titan 39 combo didn't record well, and to be honest it sounded (to me at least) no bigger/better than the Omni15. Could have been room related, but it didn't do a lot for me. Shame[/quote]It shouldn't sound all that different from the O15 at normal levels, taken into the back yard and cranked to the max the difference would be obvious. The advantage to the O10.5/T39 lies in being able to leave the T39 at home when not needed, or using it for the PA sub when there's no useful house PA.

[quote name='fretmeister' post='277764' date='Sep 5 2008, 07:56 AM']At the moment I have a LM2 and the 102HF 2x10. It sounds ace. I want to get the amp running at full output... and I just like a big amp! So I am in 2 minds whether to get another 102HF to have a virtual 4x10... or a 151HF for that classic mix. I have no idea which way to go... and I can't find a shop that has all in stock to try it out. What say you?[/quote] The result of mixing different cabs is always unpredictable. If you like the tone you have add another 2x10, be sure to stack them on end so the four tens are on a vertical line.

[quote name='Protium' post='277354' date='Sep 4 2008, 03:36 PM']Cheers mate, should it be wired parallel or in series with the woofer?[/quote] [url="http://www.partsexpress.com/pdf/piezo.pdf"]http://www.partsexpress.com/pdf/piezo.pdf[/url]

[quote name='The Funk' post='276136' date='Sep 3 2008, 06:30 AM']From the For Sale forum, a 4 ohm Mesa 6x10" (which Alex points out could be rewired to 16 ohms)... [url="http://basschat.co.uk/index.php?showtopic=22354"]http://basschat.co.uk/index.php?showtopic=22354[/url][/quote] Rewiring is probably not necessary. Unlike SS tubes are comfortable with lower impedance loads, and uncomfortable with higher impedance loads, than the nominal transformer rating.

[quote name='alexclaber' post='275673' date='Sep 2 2008, 01:10 PM']I don't know of a difference between ported and vented, they're synonymous nowadays. Alex[/quote] The officlally recognized term for a direct radiator which is not sealed is VB, for Vented Box. Precisely how it's vented is another matter entirely.

[quote name='Zerofret' post='275502' date='Sep 2 2008, 10:20 AM']I think if I was in your shoes, I would build a substantial plywood cabinet and fit something like an Eminence 15" Legend 1518 which has an SPL of 102.2dB Steve[/quote] The sensitivity ratings for raw drivers apply to above 100Hz, so that in and of itself says nothing about sensitivity where demands are highest, from 40 to 100 Hz. As for the Legend 1518, it's a guitar driver. In a typical cab sensitivity below 100 Hz averages only 92dB, and its 0.8mm xmax limits its average power handling in the bass range to only 20 watts. Sensitivity ratings given by speaker manufacturers are outright piffel and are useless for comparison purposes. But the more drivers one uses the higher the system sensitivity, as there are more driver motors utilizing the power. For that reason a lot of tens will give a better result compared to a smaller number of twelves or fifteens in the same overall pack space. With the same input two 2x10 cabs will have 6dB more output than one, and that 6dB is the equivalent of going from 50 to 200 watts. With the price of watts as low as they are today using a small amp with lots of cabs isn't the most size efficient route, but it can work if you so desire.

[quote name='tom skool' post='274979' date='Sep 1 2008, 04:41 PM']yeah perhaps but i hadnt even got halfway. I had the volume, it just didnt sound that great more farty than nice overdrive. Being all valve i should be able to drive the hell out of it without any worries right?[/quote] The main difficulty with so little power is that it takes a lot of speaker sensitivity to get a lot of clean output. In the simplest terms getting high sensitivity meann using lots of drivers, so a pair of 2x10 at the least is in order. The speaker's power rating is almost meaningless.

[quote name='alexclaber' post='274718' date='Sep 1 2008, 11:37 AM']That doesn't make sense - you are overlooking that as sensitivity goes up displacement limited power handling diminishes proportionally. Alex[/quote] Model a typical MI driver in WinISD Alpha Pro using two box sizes, same tuning, then look at the Maximum SPL chart. If the box is already at optimum size then going larger won't be of any benefit, but the number of commercial electric bass cabs which are optimum size can probably be counted on the fingers of one hand, and then after one has lost three of them in an accident. With the typical undersized alignments used going larger or smaller can make a significant difference in the low end.

[quote name='alexclaber' post='274643' date='Sep 1 2008, 10:37 AM']Also note that although the HF cabs will produce more bottom with equal power they still have the same maximum low frequency output as the HR cabs because the limiting factor is the speaker displacement[/quote]-1. Maximum low frequency output is the product of sensitivity x displacement limited power. The larger cab will go louder in the low end, assuming they use the same drivers.

[quote name='doctorbass' post='264123' date='Aug 17 2008, 02:46 PM']Has anyone played the 410 or 115 and able to give an opinion on either?? I know they have a pretty huge power handling!![/quote] Power handling is the most quoted spec to imply performance, but it's also the least significant. Those specs which are significant are not available from any manufacturer, so it still boils down to trying before buying to be sure of a happy result.

[quote name='Sean.Robinson' post='264142' date='Aug 17 2008, 03:10 PM']how much would the work you previously stated cost then to have done[/quote]More than the value of the amp. That's why if you aren't happy with the amp's inherent signal to noise performance you're better off to find a better one. BTW, I had a Hartke 3500 that was rated for S/N at 78dB. While about average for a bass amp, that would be considered unusable for PA or hi-fi. In those genres 90dB is considered the minimum acceptable, 100dB being a really good figure.

[quote name='Sean.Robinson' post='264067' date='Aug 17 2008, 01:37 PM']having looked through the forums on hiss and hum is there any chance the old tubes (16 years old) could be causing the hum/hiss, i was considering some mullards or telefunks anyhow so will be replacing them at some point but would like this clarified first please[/quote] Tubes are seldom the source of hiss. In a tube amp it's primarily the resistors, in SS the SS devices themselves, which is why tubes tend to have less hiss than SS. Tubes that aren't biased correctly can contribute to hum. Old Fender designs had what they called a hum control. The only tools required were a screwdriver and your ears, you simply turned the control until the hum was at a minimum.

[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.