Bill Fitzmaurice

[quote name='4-string-thing' timestamp='1446309701' post='2898522'] What I don't understand is why x4 the power makes no noticable difference. [/quote]Just because the Ashdown claims 4x more power that doesn't mean you were getting it. You'd only know for sure by measuring the output voltage of the two.

[quote name='fleabag' timestamp='1446302896' post='2898478'] So that guitarist was right ? [/quote]There's a first time for anything. [quote]1db is just noticable but only in the midrange ? [/quote]The midrange is what Bell Labs concentrated on, as their research was mainly related to telephone transmission, which in the 1920s was mainly in the midrange, for maximum intelligibility. They weren't so much concerned with audibility as they were transmission losses over long phone lines. Sensitivity varies with both frequency and with loudness, so 1dB as the threshold is by no means carved in stone.

[quote name='4-string-thing' timestamp='1446306541' post='2898501'] Any explanation why my 575w Ashdown Head is (seems) no louder than my 125w Acoustic head through the same cab? [/quote]To sound twice as loud as 125w you'd need 1250w. There's also the matter of maximum driver excursion. Once that's reached more power applied won't make it louder, it will only add distortion. If your cab is loaded with 40 year old drivers chances are they run out of excursion around 40-50 watts each.

The decibel scale was originally calibrated by testing a few hundred people to determine the smallest average variation that they could hear in the midrange at normal conversation levels. That variation is 1dB. 3dB is what you get with a doubling of power, 6dB is what you get with a doubling of voltage swing, while 10dB (ten times the power) is perceived as a doubling of volume level.

[quote name='4-string-thing' timestamp='1446301126' post='2898457'] This is why I find it fascinating, even though I don't really understand it.... If only it went up to 11..... [/quote]The volume control acts like a water valve. One may configure a valve to be fully open with 1/4 turn, 1/2 turn. 3/4 turn or for that matter with ten turns.

[quote name='4-string-thing' timestamp='1446291071' post='2898357'] 120 db from a 125w amp..... Maybe thats just marketing hype too? [/quote]If a cab has 100dB/1w sensitivity it only takes 100w to reach 120dB. [quote]And that it got no louder after about 3 on the volume pot![/quote]Google 'gain structure'. The position of the knob has no relationship with the output. If you were to change the volume pot value and/or taper you would change at what knob position full gain is achieved. [quote]I always thought a Watts were like a miles-per-hour rating, [/quote]They're the same as a horsepower rating. In that vein, which will go faster, a 200HP vehicle or an 800HP vehicle? That depends on issues totally unrelated to power. A 200HP BMW will go considerably faster than an 800HP tank.

[quote name='Nicko' timestamp='1446213371' post='2897790'] I'm pretty sure there is some correlation between wattage and sound power level (measured in dB). [/quote]Only in so much that with a given speaker as more power is applied SPL goes up. But there is no simple x watts= x dB calculation. [quote]The last thing we need is manufacturers confusing us with decibel ratings. [/quote]That's one of the reasons given by manufacturers as to why they don't produce measured SPL charts. It's a smokescreen for the real reasons, those being either they don't want you to see them, or they don't have them. Or both.

[quote name='cybertect' timestamp='1445424018' post='2891310'] Here's some actual testing data, that suggests there is no practical difference in the frequency response between Monster or any other cables (whatever claims they may make) [url="http://www.ovnilab.com/articles/cables.shtml"]http://www.ovnilab.c...es/cables.shtml[/url] [/quote]This is the significant point made, which is exactly what I've already said : [i]These charts demonstrate [b]that with a passive instrument [/b]a cable's capacitance has a direct correlation to the amount of high-frequency content it can carry effectively. [/i] [quote]turning the tone control down a little would achieve the same thing in a more controllable way. [/quote]Turning the tone control down a little duplicates the effect of a high capacitance cable, as it also puts a capacitive load across the pickup output. What differs is the value of the capacitor. Since a tone control is intended to roll off the highs at a fairly low frequency, 1kHz or so, the cap used has a higher capacitance value than one would usually find even in a particularly inferior cable.

[quote]The argument about cables affecting tone is pretty bogus -[/quote]I discovered the difference that cables make circa 1966, when high capacitance coiled cords (telephone handset type wire) came along and very nearly took over the market. At the time I knew nothing about capacitance, or why it could cause high frequency roll-off bordering on extreme with passive pickups, but the difference in tone was obvious and undeniable. With straight cords capacitance tends to be less of an issue, but high capacitance tone killing straight cords do exist, the Monster Bass being one example. [quote] "Tone wood" is a complete fallacy in solid electric instruments and just another device used to part the unwary from their cash. [/quote]It made a very large difference in the basses and guitars that I've built. A few decades of experimentation led me to my final choice, all rosewood neck-through with semi-hollow body chambers similar to Rickenbacker. Tone wise a solid rosewood body is even better, but the weight is too much. One might not be able to identify whether a body is made of basswood or poplar or ash without seeing the grain, but the tonal difference is considerable.

[quote name='Ghost_Bass' timestamp='1444823522' post='2886358'] My drummer is a light hitter and i love it that way. Much more comfort on stage and i don't finish my gigs with my ears ringing. We use a PA (x2 15" subs + x2 12" tops - RCF) and we send almost everything to the mix. Drum kit is mic'ed on the drums and hit-hat (no snare or cymbals), the rest is all in the PA and mixed according to the venue. This helps us keep a low on-stage volume and we can enjoy the gig better, hearing everybody, and not getting a headache. I also would say that the sound we feed to the audience is more balanced and with better dispersion doing it this way. A decent PA for pubs isn't very expensive and with class-D/Neo is small and light to carry. It will improve the band's overal sound and help you do your job better, with more quality, and win you more gigs. [/quote]I agree. The backline, including the drums, need only be loud enough to hear on stage, with the PA covering the room. For that matter I run our guitar player though the stage monitors as well so that we can hear him, since he plays a1x12 combo at sensible levels. Huge backline played at crazy levels made some sense when there was no such thing as good PA, but that hasn't been the case within the lifetimes of most players today.

The point is that the average club band doesn't have a big enough system. They need to get the most possible out of the least amount of gear. That very much takes cardioid sub arrays and freestanding subs off the table.

[quote name='ironside1966' timestamp='1444164850' post='2880888'] I personally don't see the point in putting the subs at the back [/quote]The reasons for not placing subs out front is the resulting cancellation notch from Allison Effect, and the loss of boundary loading. It's true that the vast majority of users don't wall load their subs, and they split them left/right under the mains. Those are the two most often seen errors in subwoofer placement, by users who don't know what Allison Effect, boundary loading and the power alley are. I wouldn't put them on stage, I'd put them to one side or the other. As for the rumble, since the output of subs is omni-directional it won't matter much to the band if the subs are in front of or behind them. That's also why off to one side or the other will work equally as well as directly behind.

Subs in the back, or off to the side but still close to the back wall, is what you want. But only subs, running no higher than 100Hz, not full range cabs.

[quote name='Tdw' timestamp='1444071221' post='2880091'] Out of interest, what sort of cable would you suggest between a passive bass and a valve amp? A short one, or is it more than that? [/quote]As short as possible with the lowest capacitance you can find and 100% shielding. There are capacitance specs available from various wire manufacturers, like Belden, Canare and Mogami.

[quote name='PaulWarning' timestamp='1444066723' post='2880026'] reminds me of the great speaker/connect cable debate in the world of HiFi. The cynic in me tends to believe that charge someone enough money for something and they'll convince themselves they've not been ripped off, but, like I said I'm a cynic, and one with hearing damage as well [/quote]Hi fi interconnects and speaker cables are a different beast entirely, and yes, there's no justification for high prices there either. But they differ in that they don't have to deal with high impedance pickups driving relatively low impedance loads, ie, valve amplifiers. It's that particular combination that demands very low capacitance cables for best results. That's not the the case with interconnects between line level devices or speaker cables, or low impedance mics, nor for that matter active basses.

[quote name='discreet' timestamp='1443982901' post='2879212'] I currently believe that a one-piece maple neck on a P has a sound all its own [/quote]It does. All of the wood parts have their effect, based on their density. A maple versus rosewood fretboard won't make as much difference as an ash versus poplar body, but there will be some.

[quote name='TomRichards' timestamp='1443962606' post='2878978'] My local shop made me two cables about a year ago, and one of them was "bad". We tested them on the bench, and they both had the correct outputs. However, when we plugged them into the amp, one lacked all the higher frequency and top end. [/quote]That's an indication of high capacitance. It's very odd that you got different results with two cables cut from the same spool. The good news is that you need not spend more than a pound per foot for cable with the lowest capacitance and highest degree of shielding possible. Don't believe claims made for better performance from cables costing more than that, not even a hundred times more. If anything high priced exotic cables tend to have poor capacitance. Monster Bass cable is one example. It's capacitance is so bad that any reputable company would consider it defective and not sell it at all. Monster, however, is not reputable. [quote]But do cables have a major influence on tone? In my opinion, no[/quote]A good cable will have no effect, but a bad one will, and not in a positive way.

[quote name='lowhand_mike' timestamp='1443621142' post='2876325'] nothing like a bit of light reading for a wednesday afternoon, and thats nothing like a bit of light reading can you give us the concise version please bill? [/quote]http://barefacedbass.com/technical-information/speaker-size-frequency-response.htm

[quote name='JTUK' timestamp='1443608928' post='2876117'] My take...and it may not be the kiondest... is that players and bass players in particular, are stuck in the 80's... [/quote]More like the 30's. The answer to the basic question posed can be found here, published in 1940. http://www.introni.it/pdf/Olson%20-%20Elements%20of%20Acoustical%20Engineering%201940.pdf

[quote name='tauzero' timestamp='1443445768' post='2874712'] Does a rear port make any difference to that?[/quote]You shouldn't place a rear port tight to the wall, but three inches or so of air space is sufficient. [quote] A little thinking (which is possibly less than the minimum required) suggests that it would actually exacerbate the problem as the out-of-phase sound from the rear port would be additive with the sound from the front. [/quote]The sound from a port is not out of phase, at least not within the cabs intended pass band.

[quote name='discreet' timestamp='1443395071' post='2874406'] So it could be the case that I actually like the sound of a sealed cab, albeit one that just happens to have 10" drivers in it... [/quote]+1. For the most part sealed cabs do sound different than ported. It would be interesting if Ampeg had gone with twelves or fifteens instead of tens with the SVT. AFAIK the only reason they did go with tens instead of twelves was that they wanted to use 32 ohm drivers so that they could be parallel wired for a 4 ohm load, and there weren't any 32 ohm twelves available.

[quote name='geoham' timestamp='1443388155' post='2874367'] Presumably the 2.8 feet is measured from the back of the cab? [/quote]From the front.

[quote name='discreet' timestamp='1443354523' post='2874030'] I really don't understand why Alex comes in for so much flak on here and elsewhere. [/quote]It's because Alex tells it like it is, and people don't like having their pre-conceived subjective notions countered with factual objectivity. If the big manufacturers were concerned with anything but sales numbers they'd all have something similar to this on their websites: http://barefacedbass.com/technical-information.htm The fact that none do is telling. Where driver size is concerned this is pretty much definitive: http://barefacedbass.com/technical-information/speaker-size-frequency-response.htm But the ranks of those who'd rather cling to unfounded myth is legion, in any field.

[quote name='Musashimonkey' timestamp='1443295666' post='2873708'] My understanding is the wavelength will vary depending on notes played etc, but what's a good rule of thumb for how close to be to a wall for boundary reinforcement? [/quote]The general rule is to keep the cab as tight to the wall as possible. When the distance from the wall to the front of the cab is 1/4 wavelength you get a cancellation dip at that frequency, as the original and reflected waves meet 180 degrees out of phase. If the cab is, for instance, 16 inches deep that puts the 1/4 wavelength frequency at about 210Hz. Pulling it out further lowers the 1/4 wavelength frequency. There is a circumstance where you might want to pull it further out, that being a boomy stage. If you match the 1/4 wavelength frequency with the resonant frequency that causes the boom you can use the one to cancel the other. Boom generally takes place around 100Hz, where 1/4 wavelength is 2.8 feet, so that's a good distance to try.

[quote name='Chienmortbb' timestamp='1443034535' post='2871740'] Yes if you put it on a chair you will ruin the mutual coupling effect that the floor gives and loose a lot of the bottom end. [/quote]Only if raised by at least 2.8 feet. Still, I prefer a combination of tilting and lifting to aim the cab at your head. Tilting alone with a small cab can aim the mids above the audience. BTW, 'mutual coupling' is the technical term for when two cabs are placed together. Boundary reinforcement and space loading refer to when the cab is placed less than 1/4 wavelength from the floor and/or walls.