Bill Fitzmaurice

[quote name='Mr. Foxen' post='1146515' date='Mar 1 2011, 05:19 PM']Just put it somewhere else. The purpose of cabs is to put sound into a room first, amp stand second.[/quote] +1. Worrying more about how the rig looks or stacks instead of how it sounds should be left to guitar'd players.

[quote name='dannybuoy' post='1143155' date='Feb 27 2011, 06:37 AM']I've heard on numerous occasions that valve amps 'like' sealed cabs. Why is this? Do valve amps behave differently when connected to sealed/ported cabs?[/quote]It's not the sealed cab per se, it's the high Q drivers used in them. The result is a lower peak impedance than low Q drivers in vented boxes, which keeps the circuits happy. From a response aspect a high Q sealed cab tends to be more sensitive in the midbass than a vented cab, and that makes the rig subjectively sound louder, a plus with the generally lower power of valve amps. A very high Q speaker is how one can gig with 25-35 watt Ampeg Portaflexes. The downside to high Q sealed cabs is a thin low end compared to vented cabs.

The benefit is that the net volume of the cab, not including the second driver and plenum between them, is halved. The downside is that the output remains the same as that of one driver, and the driver cost is doubled.

[quote name='challxyz' post='1142194' date='Feb 26 2011, 06:28 AM']i'd like to use the 1x15 and the 410 but impedances are not matched,[/quote] In most cases you don't want them matched. The average 1x15 does not have either the thermal or the displacement limited capacity of the average 4x10, so if both are 4 ohm receiving the same power the 1x15 is the weak link in the chain. That's especially the case with a 410HLF Your positive experience with a 2x10/1x15 should be telling you something: it takes two fifteens to make a good match with four tens. The exception to this would be a high excursion 15, such as the Eminence 3015LF.

[quote name='Phil-osopher10' post='1141579' date='Feb 25 2011, 01:42 PM']I recently purchased a 20W combo made by a orange. Would it be fair to judge most orange amps and such on this amp ie. fundamental sound? rather than spending loads and loads trying figure out if they are for me or not?[/quote] You can't judge any brand by the least expensive product they produce, unless their least expensive costs more than what the competition charges for their better products. For instance, I wouldn't call Toyota a producer of bad cars based on the Yaris. But you can't buy a BMW at a Yaris price either.

[quote name='Dronny' post='1140938' date='Feb 25 2011, 05:48 AM']I'm unclear on whether the bass cab would be any use for this...[/quote]It will not, as it probably goes no lower than what the PA tops do. True subwoofers go at least an octave lower than bass cabs.

[url="http://www.ampwares.com/"]http://www.ampwares.com/[/url]

[quote name='fryer' post='1125710' date='Feb 13 2011, 04:54 AM']Hi, I have two 410 cabs. One is a Peavey, 450 w at 4 ohm, and the other is ( or soon will be ) an Epifani, 1,000 w at 4 ohm.[/quote]The power rating of the speakers is moot. Driver displacement determines how much power they can make use of, not the thermal rating. Too bad not one major manufacturer will reveal the displacement limited power of their cabs, though in deference that's partly because most of them don't know themselves. Should you need to separately adjust their volume you can only do so with an amp that has dual independent power amps.

[quote name='dincz' post='1123204' date='Feb 10 2011, 04:03 PM']I realise that vertical stacking reduces the vertical dispersion, but does it also widen horizontal dispersion?[/quote]It does not[quote]if there's less vertical spread then it has to go somewhere else.[/quote]It does, into the audience. Making the source higher extends further out from the source and further down in frequency the zone of the nearfield condition, where SPL drops at a 3dB per doubling of distance from the source rather than the 6dB of the farfield condition. Going from one cab to two doesn't extend the nearfield all that far, but it does extend it, four times further than with one cab to be precise.

[quote name='alexclaber' post='1121592' date='Feb 9 2011, 12:19 PM']Phil's explanation is correct but it's easily misunderstood because it's referring to ALL loudspeakers. If you look at the small subset that represent bass guitar drivers then there's plenty of room for 8"s to go lower than 15"s and 12"s to have more mids than 10"s.[/quote] True. The fact of the matter is that drivers created for use in electric bass speakers have similar specs, because they're all intended to work within the same bandwidth. And that being the case there's very little difference between them in how they function where performance is dictated by the specs. Dispersion is the exception, as dispersion isn't dictated by specs, it's dictated by the dimension of the radiating plane.

[quote name='alexclaber' post='1120399' date='Feb 8 2011, 01:35 PM']Except that I've heard plenty of Peavey 2x10"s and 4x10"s with more bottom and less midrange than many Peavey 1x15"s and 2x15"s. And so on and so forth... It's still bollocks. The old rule of thumb only holds up if you ignore the numerous exceptions - but they really are too numerous to ignore.[/quote] +1. When the exceptions are the rule there is no rule.

[quote name='Phil-osopher10' post='1119991' date='Feb 8 2011, 07:45 AM']So looking at cabs and the different configurations that you can get, it got me thinking what are the difference in the sizes of the speakers? Do they produce different wave lengths and thus produce different sounds? I just don't get it.[/quote]In and of itself the only factor influenced by driver size alone is the angle of dispersion. The larger the driver the lower the frequency where beaming takes place. Nearly everything else is determined by the driver T/S specs. [url="http://www.eminence.com/support/understanding-loudspeaker-data/"]http://www.eminence.com/support/understand...udspeaker-data/[/url]

[quote name='basses' post='1117798' date='Feb 6 2011, 11:00 AM']Are these drivers in some way unsuitable?[/quote] They're very good drivers. Whether they're suitable for your cab is a different question entirely. Ideally they'd have the same or very close to the same T/S specs and midrange response as the drivers you replaced.

[quote name='rubis' post='1115694' date='Feb 4 2011, 01:13 PM']What would be a suitable replacement or upgrade speaker...[/quote] One with the right T/S specs and midrange response. Brand, size, wattage and most of the usual considerations given when choosing drivers tend to be irrelevant. T/S specs explained here: [url="http://www.eminence.com/support/understanding-loudspeaker-data/"]http://www.eminence.com/support/understand...udspeaker-data/[/url]

[quote name='Bloc Riff Nut' post='1109968' date='Jan 31 2011, 02:54 PM']I don't know how to cut 100Hz using the EQ of my Markbass CMD 102P.[/quote]Unless you have a graphic or parametric EQ you can't cut one frequency. Even with those you can only cut a band of frequencies centered at or near 100 Hz.

[quote]Putting casters on a cab should decouple it from the floor, right, so is there a reason NOT to do this?[/quote]There is no such thing as mechanical coupling, so don't worry about that. But less than perfectly level floors can result in the cab being tippy, or one caster not having any load on it, and it may then rattle. Carry some bits of foam rubber in your kit to put under the casters in that case.

[quote name='2008escottp' post='1100314' date='Jan 23 2011, 06:47 PM']Might be a stupid question but I'm a novice with this. If I have a 500watt amp and want to run 2 separate speaker cabs, do they both need to be at least 500watts?[/quote]Preferably. That's because most speakers will only take half their thermal rated power, if that, before reaching their maximum output capability. It would be nice if manufacturers provided both the thermal rating and the displacement limited power rating, but not a single major manufacturer does. Ampeg is the only major manufacturer that consistently has very conservative thermal ratings, which are close enough to the displacement limited ratings so that you can safely assume them to be accurate and useful.

[quote name='GUI101' post='1098200' date='Jan 21 2011, 06:06 PM']I checked out their websites and they don't do 18inch speakers unless you are a manufacturer and buy in bulk. anyone have any ideas or advice??[/quote]Buy one from a retailer.

[quote name='icastle' post='1095871' date='Jan 19 2011, 07:45 PM']Unfortunately, 50KΩ is not a preferred value so you're not going to find it in Maplins.[/quote]100K will do in a pinch.

[quote name='willyf87' post='1088179' date='Jan 13 2011, 10:39 AM']Got a little giant 1000 and a schroeder cab on the way. I see there are 2 pin and 4 pin speakon cables out there, which do i need and can anyone tell me the difference?[/quote]Whatever the respective owner's manuals say you need.

[quote name='fretmeister' post='1084722' date='Jan 10 2011, 02:44 PM']So disconnect at the "non-tweeter" end of the wiring?[/quote] Disconnect the high-pass filter.

[quote name='icastle' post='1084688' date='Jan 10 2011, 02:26 PM']No other wiring needed - just disconnect it (make sure you don't leave bare wires or connectors floating around inside the cab though). [/quote] That leaves the potential for the amp to see a dead short at the filter corner frequency. The disconnect should take place before the high-pass filter.

[quote name='bassman2790' post='1082948' date='Jan 9 2011, 05:18 AM']How much 'real' volume difference is there between 450W and 170W or even between 300W and 170W?[/quote]Not enough to be concerned with, because for the most part watts are moot. What does limit output is driver displacement. Going from a total of eight tens to two reduces displacement by 75%, which combined with the 75% reduction in power handling reduces maximum potential output by 12dB. In simple terms a 2x10 will sound somewhat less than half as loud as two 4x10s. You're probably best off going to a pair of 2x10s , that way you can use the one if the gig is small enough to get away with it, both when it isn't.

[quote name='TimR' post='1081637' date='Jan 7 2011, 06:16 PM']As Bill intimated earlier. The power output is not linear. This is why you get power compression at the top end of the amplifiers range.[/quote] Linearity in audio is rare. It isn't with speakers, it isn't with amps. If I designed amps for a living instead of speakers I'd have the reason for this particular non-linearity at the tip of my tongue, but it lies too far back in the recesses of my memory to retrieve it.

[quote name='flyfisher' post='1081561' date='Jan 7 2011, 04:57 PM']Hmm. Not sure. PSU inadequacy seems, to me, to be an economic issue rather than a purely technical issue, i.e. the limitation [u]could[/u] be eliminated by design.[/quote]I believe that it's not the PSU, it's the output devices. Somewhere in my files I've got the reason why amps can't double their full power output when the load impedance is halved. Of course I can't find it when I need it. If it could be done you'd see it done, and it isn't.