Bill Fitzmaurice

Most line drivers provide sufficient voltage to drive phones, but they won't handle a low impedance load. If you can find phones or buds of at least 600 ohms impedance it would be worth a try,

[quote name='mcgraham' post='84471' date='Nov 6 2007, 10:45 AM']I got the impression he was a violinist based on all his in class examples and in discussion examples, so perhaps a bit of classical prejudice there.

I am personally of the opinion that it does make a difference, but that the impact of construction/craftsmanship, pickup location and type along with amplification is greater. I'm not sure to what extent this is true (sometimes I'm not even sure it is!) but I'd perhaps venture out to say to a greater extent rather than a lesser extent.

What are your thoughts Bill? Feel free to tear me a new one if you think otherwise.

Mark[/quote]
They all factor in. Your lecturer probably based his bias on the concept that solid bodies don't have vibrating tops. The problem with that concept is that it's incorrect, solid bodies do vibrate and do have resonance signatures that contribute to tone. Those resonances aren't as potent in the final result as amp EQ or speaker coloration, but OTOH put mic'ed violin through an effects board and guitar amp and you wouldn't be able to tell a Strad from a Strat.

[quote name='mcgraham' post='84334' date='Nov 6 2007, 04:06 AM']I studied physics at uni but never got to discuss much about such things there, although I had a great chat with a lecturer about sound waves and resonances specifically pertaining to electric instruments and how (in his rather authoritative and professional opinion) there should be little to no effect on the sound of a solid body electric instrument as a result of the woods it is made from...
Mark[/quote]
Obviously not a player he, and IMO not much of an acoustician either. The mass and density of not only the body but all else as well makes as much difference with an electric as it does with an acoustic. One of Les Paul's early goals was to remove the body as a factor in tone, but early on he realized that short of using solid granite that goal was unacheivable. He didn't settle on a maple top over mahogany back just because of how it looked.

Continuous Power = Real World Rating (volts x amps= watts)
Program Power = Inflated Rating for Advertising Purposes
Peak Power = The Engineering dept has been sacked, only Advertising dept remains.
Peak Program Music Power = If You Buy This You'll Buy Anything.

[quote name='OldGit' post='84206' date='Nov 5 2007, 03:43 PM']So could the effect be achieved by any cab with the right eq settings?
It seems to be "more different" than that ...[/quote]
Here's what happens when you load a 4 cu ft cab with either one (yellow trace) or two Eminence (blue trace) 2512 twelves.

With two twelves sensitivity jumps above 80 Hz, but dies below that. Above 80 Hz the ear is literally twice as sensitive as it is below 80 Hz, so there is a major difference in the relative 'loudness' of the two cabs, despite their being the same size. The trade off is that it will take four times the amplifier power to get the same output below 80 Hz from the 2x should you wish to do so.

[quote name='OldGit' post='84189' date='Nov 5 2007, 03:18 PM']Bill can you explain how the Schroeder cabs allow us to be heard clearly all over the stage and venue at a relatively low volume?
It's intriguing
Thanks[/quote]
Search 'Fletcher-Munson' curves. The ear is more sensitive to midbass than low bass frequencies, and Schroeder cabs accentuate the midbass.

[quote name='fusionbassist1' post='84147' date='Nov 5 2007, 02:02 PM']I'm sure that more sound is usually thrown out of a cabinet (or set of cabinets) with a large speaker area than one with small area. as in a 8x10" cab on it's own has 80" speaker area and a 2x10 paired with a 1x15 has 35" speaker area, unless I'm missing some very basic math here.[/quote]
You're only thinking in two dimensions, whereas the maximum output of a driver is determined by the product of cone area (Sd) and maximum excursion (Xmax), the result being the three dimensional parameter of displacement (Vd). You can find explanations of driver parameters and how they affect performance here:
[url="http://www.eminence.com/resources_data.asp"]http://www.eminence.com/resources_data.asp[/url]

[quote name='gypsymoth' post='84016' date='Nov 5 2007, 10:29 AM']it doesn't hurt to have a high rated speaker,[/quote]Sometimes it does. Output is limited primarily by driver xmax. Where that's concerned a 150 watt Eminence Basslite S2010 will put out more than a 350 watt Kappa Pro 10. There are other pertinent factors as well, for instance the driver Qts. In the case of the S2010 versus the Kappa Pro 10 the very low Qts of the Kappa Pro chokes off its response over an octave higher than the S2010. In most cases drivers with very high power ratings are accompanied with low Qts values, so if you buy a cab with a very high power rating in the quest for more bass output the opposite may be the result.

[quote name='mcgraham' post='82236' date='Nov 1 2007, 08:38 AM']there is a limit to the number of laws of physics that Jorg can break, and he's already broken his quota.[/quote]
Au contraire, his cabs do exactly what the laws of physics demand that they will. In this case it's Hoffman's Iron Law. When you make the cab volume that a driver operates in smaller sensitivity rises, at the expense of low frequency response. It sounds louder, but doesn't go as low. If you want to go both loud and low you must go larger as well.

[quote name='billynoband' post='84091' date='Nov 5 2007, 12:18 PM']The best thing you can do with any 2x10 cab is to build a BFM Omni 10 , take the speakers out and put them in the homemade cab. Its the only BFM design that you can use any bass speaker in.[/quote]I wouldn't go that far. It's not a very demanding design of the driver used but the garbage in garbage out rule still applies.

[quote name='fusionbassist1' post='83985' date='Nov 5 2007, 09:41 AM']ah ok then, i was just thinking in terms oh looking at cabs via tinterweb before trying them out and in turn purchasing them.[/quote]
Whilst manufacturers provide wattage ratings as the primary guide to performance said ratings are the least reliable indicators of same. And, since the indicators you need to make valid comparisons from specs only are not available, your only recourse is to get thee into Ye Olde Music Shoppe and try until you find what you want to buy. Then you find the best deal, which, BTW, may not be on the internet. Web salesmen can't cut deals.

[quote name='fusionbassist1' post='83976' date='Nov 5 2007, 09:19 AM']Thanks for that Bill.

Just one thing, to get the best performance possible out of a bass cabinet and amplifier, should the power handling be as close to, if not over what the amp's able to shed out. If I've understood correctly this should keep the speakers a decent distance away from it's maximum travel limit.

Have I got this correctly?[/quote]
Ignore the cabs power rating. If it goes as loud as you need without distorting it's powerful enough, if not chances are you need a larger or better cab or a second cab. As far as cab to amp power ratios are concerned, thanks to the volume control you can never have an amp that's too powerful. Having plenty of reserve power at hand is never a bad thing.

[quote name='Crazykiwi' post='83964' date='Nov 5 2007, 08:52 AM']Bill, what would be your take on a situation where you have a 400w valve amp that sounds fine with one Acme 2x10 cabinet but the lower frequencies distort when two 2x10 cabinets are plugged in? Are the cabinets testing the amp, or is the amp testing the cabinets?

The amp has been serviced and checked out by a trusted amp tech who says that the amp is fine and putting out roughly 360W.

The cabinets have worked fine with solid state amps.[/quote]
Short of using testing gear that you probably don't have the best way to see if amp headroom is the culprit is to drive the second cab with a second power amp of at least equal power. If two amps works better you know that insufficient power is the problem.

[quote name='gilmour' post='83761' date='Nov 4 2007, 06:41 PM']To my understanding that means if it the only speaker cab connected it should be ok as the amp is 250 watts @ 8 ohms. I think - but I've always been a bit confused with this stuff.[/quote]
The power ratings of both amps and speakers is not what matters. If you overpower speakers they will blow, but you'll almost always have warning well short of doing so in the form of distortion. Amps are capable of long term output well above their rated power, and short term surges of at least four times their rated power, but it will be a distorted output. Here again that distortion will tell you that you've gone beyond the bounds. Ignore that warning at your own peril.

The power rating of drivers is a thermal rating, and does not reflect real world power handling capability. For electric bass that is usually defined by displacement, how much power may be applied before the cone reaches the end of its travel limit, and that is usually only 25 to 40% of the thermal rating.
In the vast majority of cases if you exceed the displacement limit there will be a lot of distortion, and the cure for doing so is simple. Turn it down. If you don't apply enough power to create distortion, by either overpowering the drivers or pushing the amp beyond its limits, the likelihood of blowing drivers is remote.

[quote name='far0n' post='83557' date='Nov 4 2007, 10:49 AM']Right ok, so if that's the case why would Markbass manufacture the same cabs but in rear and front ported formats ? Seems a bit odd to me ![/quote]
The internal volumes of the cabs are different, the rear ported being smaller. The ports were put on the rear as they wouldn't fit on the front. Response of the larger cabs is better in the low end, because they are larger, not because of the port location.

[quote name='nedsbeds' post='83325' date='Nov 3 2007, 05:46 PM']nor does he design direct radiators though![/quote]
Actually, I do, but mainly those are home theater line arrays. As to the location of the port, its location makes absolutely no difference whatsoever. The frequencies radiated from the port do so in a completely omnidirectional pattern, so it makes no difference which way the port faces. Rear ports and walls are only problematic if you slam the cab flush against the wall and seal the resulting joint airtight.

[quote name='Jack' post='83236' date='Nov 3 2007, 02:56 PM']Are they that much cheaper?[/quote]Less than a quarter as much. At manufacturer's cost the difference is perhaps a pound. Multiplied by a few thousand units used in a year's production that pays for a week or two on the Cote D'Azur for the CEO. Which is of no great consulation if it's your amp toasted for the lack of Speakons.

[quote name='Jack' post='83195' date='Nov 3 2007, 01:23 PM']Speaker signals shall not go anywhere except unto speakers!

Glad to hear things arent totally FUBAR, it would suck to lose two amps like that. [/quote]
And the Lord looked down upon the World and Saw the folly of using the Quarter Inch Jack for both the Input and the Output, and he was filled with sorrow. And so he spake unto Neutrik and sayeth he: "Fix it!"
And Lo was created the Speakon.

[quote name='Gwilym' post='82878' date='Nov 2 2007, 03:00 PM']as long as it handles a low B adequately, then I'm happy[/quote]
That's quite at odds with a true 'vintage' tone; my 65 Fender Bassman wouldn't go below G before going apoplectic. But todays drivers aren't so anemic. An OTop 12 will handle a low B, the question is whether you'd need a 1x12 or 2x12 to get the levels you want.

[quote name='Gwilym' post='81947' date='Oct 31 2007, 05:06 PM']hi Bill,
thanks for your thoughts - pretty much exactly what Steve explained to me too . Now I do like the idea of this cab, and if I can get up to Northampton and Steve has one built, I would love to try it. But! I'd still like to keep the bottom end if possible. Which of your cab designs would you recommend on that basis? thanks! [/quote]
That depends on what your definition of a good bottom end is.

[quote name='Gwilym' post='80991' date='Oct 29 2007, 04:17 PM']BFM Omni 12 Top (maybe without the tweeters) as recommended by Thumper[/quote]
If he has one I'd give it a try. 'Vintage' translates to weak bottom, strong midbass and midrange, and a weak high end. That's the way cabs of the 60's sounded because that's what the drivers and cabs of the day were capable of. The OTop 12 and 15 are PA tops by design, meant to be used with subs, and that means a weak bottom, strong midbass and midrange, and, when built sans tweeters, a weak high end. The result is very much a vintage tone, but between using modern drivers and cabinet technology a lot louder than their 1965 counterparts. Very different animals from the more hi-fi Omni models.

[quote name='ZPQ' post='80224' date='Oct 27 2007, 03:02 PM']If you only have one monitor mix you could have the subs from an aux and the tops in stereo.[/quote]True, but never buy to suit only your current needs, always plan for future system expansion.

[quote name='fusionbassist1' post='80147' date='Oct 27 2007, 10:48 AM']If anyone has absolutely any muses about 18" speakers to share pelase do as i'd much appreciate all the info I can get. I haven't had much response in other topics so i'm still a bit overwelmed. Anything at all...honestly....Thanx a lot everyone,

FB1[/quote]My main advice with respect to an 18 is don't use one. Modern drivers don't have to be so large to deliver what you need, and as far as electric bass is concerned there's no need for an 18 whatsoever. Beyond that, response, sensitivity and usable output are determined by the combination of the cabinet and driver, and they must be precisely matched to work correctly. You can't separate the function of the one from the other, so if you're thinking about loading a new driver into an old box you'll have to use a speaker design program to find out what will work best in that box.

[quote name='Boy Thunder' post='80195' date='Oct 27 2007, 01:18 PM']My band has the same stage snake setup... 16/4

I have the crossover on the stage with the effects so I run 2 sends for that.. my other 2 sends run the monitors..ope thats a help...[/quote]
With the crossover on the stage you can't run an aux feed to the subs, which is far more versatile. Get the 6 returns or get a few extra mic sends, all you need to convert them to returns is an XLR gender adaptor.

[quote name='BassBalls' post='77749' date='Oct 22 2007, 10:38 AM']Im not sure i totally understand what your saying. :wacko: So basically, i need to have a separate lead coming out of my speaker outputs on my head, put these both into an active frequency crossover "box," then have two outputs going into the separate cabs?[/quote]
That is what you would do with a passive crossover. An active crossover takes the output of a pre-amp, splits it to high and low outputs, each feeding a separate power amp to drive the cabs individually.