Bill Fitzmaurice

[quote name='LawrenceH' post='1063054' date='Dec 18 2010, 06:02 PM']I can see where you're coming from but a 45-year-old recording from the dawn of the roundwound, multitracking and close-mic-ing era is hardly representative of 'most' record producers I think they got with the program pretty quickly, and they were pretty good at getting acoustic jazz recordings down by the late 50s.
This true live sound, would be the same one that was on the typical low-xmax, undersized box pre TS speakers used by most artists of the day? With the need to be loud enough that's gotta be at least as limiting as the recording aspects.[/quote]All I know is that, with the exception of 'My Generation' where the bass solo would have been pretty silly sounding low-passed at 1kHz, the tone heard on 'The Who' recordings bore no resemblance to the Ox live.

[quote name='LawrenceH' post='1062972' date='Dec 18 2010, 04:13 PM']Getting a meaty bassline to jump out of a tranny radio without absolutely shagging the speakers places quite tight constraints on how you commit it to record! But most record producers are clueless? I wonder how most pop records were 'meant' to sound?![/quote]
There's two lines of thought there. One is the way the producer wants it to sound, the other is true to the band's live sound. Ent made it no secret about how he felt about the butchering of his tone, which was accomplished by low passing so severe that his RotoSounds ended up sounding like tape-wound LaBellas. It had nothing to do with modes of playback, everything to do with conformity, and most odd that Ent put up with it.

[quote name='TimR' post='1062593' date='Dec 18 2010, 11:01 AM']2). Soundman is not always your best friend - ideally you have your own who knows what you are supposed to sound like. Alternatively the venue soundman listens to your band playing and talks to you before even touching his PA and learns very quickly what you want.
In reality you get someone who is only interested in turning the system up to 1.1 gigawatts to show it off.

3). Bands don't have producers - Someone who listens to your tracks and says OK I know you like that fill there, or you like that bass tone, but guys - it's just doesn't work live.[/quote]When it comes to getting the bass right in the PA I'd say 90% of soundmen are clueless. Record producers aren't much better; I only heard the Ox's true tone on one track, 'My Generation'.

[quote name='Chopthebass' post='1062144' date='Dec 17 2010, 06:54 PM']Hilarious [/quote]
I though it odd that a thread about one myth, having too much power on tap, went so long without the even more pernicious myth, that of under powering, being raised. To have the same poster apparently believing both to be true: priceless.
No offense to the OP.

[quote name='Lozz196' post='1061620' date='Dec 17 2010, 09:36 AM']I would need to use both cabs all the time, to obtain the 450 watts at 4 ohms, [b][i]due to under-powered issues[/i][/b].[/quote]

[quote name='Phil Starr' post='1059843' date='Dec 15 2010, 01:35 PM']I agree with you about the speaker making not much sense as a piece of design. It just seems lazy to me, but I might be missing something.With a magnet giving Qts of 0.29 there's leeway for lowering the response or using a longer voice coil as this thing is still excursion limited.[/quote]
It probably boils down to money. You can get a lot more out of an eighteen than the Sigma will give, but the cost would put it beyond the price point that Yamaha can command.

Perhaps the cab design pre-dates the woofer, and it was originally loaded with a driver that need a larger box. That, or Yamaha wanted to go lower than what 175L allows. IMO an eighteen loaded cab with a 50Hz f3 makes little sense.

[quote name='Big Mick' post='1055329' date='Dec 11 2010, 02:52 PM']Ooohhh, the top is on, very exciting!!!

[/quote]Where are the braces???

[quote name='Raph' post='1054527' date='Dec 10 2010, 04:37 PM']Eminence BP102-4

Anyone have a cab using one or more of these? If so, any opinions?

I'm intending to make a 1x10" cab to use with 250-300W amps, not intending to use extension cabs therefore 4ohms.

It's rated at a rather weak hifi-esque 90.5dB/W/m but I've compared the freq curve to speakers rated at 98-99 and most of the usable frequencies are only 2-3dB down, and there's a big dip in the 500-2k range[/quote]
The answers to your questions are to be found on the SPL and Maximum SPL charts when you model the driver in the proposed cabinet and compare the result to other drivers. Manufacturer driver data sheet charts don't reflect results in an enclosure, only response above 200Hz, and they don't show maximum SPL.

[quote name='LawrenceH' post='1055428' date='Dec 11 2010, 04:25 PM']Not sure I get the sense of what you mean with the arrays though, crossover points there are more determined by the constraints of the vertical spacing with respect to the lows and mids.[/quote]
The vertical spacing doesn't enter into it, as the distance between the LF and mid elements of adjacent cabs in stacked arrays is less than the CTC distance between those within each cab. For example, the JBL Vertec VT4888. The woofer CTC is about 24 inches, which is 1wl at 565 Hz. The CTC distance from woofer to woofer in adjacent cabs is about 15 inches, 1wl at 900Hz.
The actual crossover used is 350Hz, well below the maximum allowable of 565Hz. That's all about system efficiency, as the direct radiating woofer sensitivity is only 98dB, whereas the horn loaded mid sensitivity is 102dB.

[quote name='LawrenceH' post='1055062' date='Dec 11 2010, 10:43 AM']Second, regarding the more complex comb filtering that one gets at greater-than-1/2-wavelength spacing, I wonder about allowing full-range signal to (or exit from) only a subset of the drivers in the stack, it's an obvious idea so it must have been implemented in some systems in the past. Even considering the typical 4x10 though, I wonder how much difference it really makes in practice to perceived (rather than measured) tonal consistency. Ears tend to be a lot more forgiving of changes to electric instrument sounds than, say, vocals.

I must say I've not heard the PJB stuff, I would be interested to.[/quote]I can't say what PJB does, but to work as well as possible they should have the outermost drivers low-passed at their 1 wavelength center to center distance, the next set lowpassed at their 1wl/CTC, etc., culminating in a center row run full range. This is a commonly seen scheme with horizontal TV center channel speakers, and for that matter it's how the crossover points are determined with multiway PA line array cabs with with woofers outermost, the tweeters in the center and the mids between the two. The short CTC distance of the PJBs is no panacea. The result of using a number of drivers horizontally placed without appropriate filtering can be seen in applets such as those found here:
[url="http://www.falstad.com/mathphysics.html"]http://www.falstad.com/mathphysics.html[/url]

A 4x10 done correctly would low-pass one vertical pair of drivers at the 1wl/CTC frequency.
A friend built a 4x12 for his guitar playing son, including what he called a 'sweet switch'. The son greatly prefers the sound of the cab with the switch engaged. Unbeknown to him so doing turns off one of the vertical driver pairs.

[quote name='billyapple' post='1054707' date='Dec 11 2010, 04:35 AM']So would having two 410's (or indeed an 810) on top of each other be like having two vertically stacked 410's next to each other?[/quote]I think you meant to say two pair of vertically stacked 2x10s next to each other, to which the answer would be yes if the horizontal driver spread is the same. IMO there's no reason to need more output than what three 2x10s will give, and they could all be vertically stacked. If the form factor allows it the amp could be placed beneath the uppermost cab for ease of access.

[quote name='Big Mick' post='1051078' date='Dec 7 2010, 04:45 PM']Although Bill's plans are pretty comprehensive with regard to cutting lists, component selection and assembly drawings, they don't provide some of the useful little tips, like what order to assemble the spacer and tee nuts in.[/quote]That's because I recommend using screws. A 4kg driver doesn't need the strength of bolts, and screws into 24mm of material have all the holding power one could need and more.
[quote]It's Evo-Stick Serious Stuff ultimate strength adhesive, £7.95 at B+Q. Not sure it it's the same as the PU stuff that Bill uses[/quote]It doesn't appear at all the same. PL Premium expands to triple volume.

[quote name='fretmeister' post='1053960' date='Dec 10 2010, 07:55 AM']So - does it actually work, or is it another DFA thing like on the Accugrooves?[/quote]
It will work if the driver has dual voice coils.

[quote name='jonthebass' post='1053221' date='Dec 9 2010, 02:07 PM']Am I right in thinking this is why the two 2x10" cabs stacked vertically is pretty much the ideal setup?[/quote]Yes, that way you don't reduce horizontal dispersion, you do reduce vertical dispersion to limit the output wasted going to the floor and ceiling, and you can hear your mids better as they pass closer to your ears rather than below the waist. Maybe not ideal per se, but for sure the best way to employ 2x10s. This explains why many players prefer a vertical 2x15 to a 4x10. Even though the individual tens have wider dispersion than the individual fifteens the 4x10 configuration squanders the potential offered by the tens.

[quote name='jonthebass' post='1053099' date='Dec 9 2010, 12:32 PM']I use two modern 1x15" cabs and the sound is all there up to 4kHz.[/quote]Not if you move over a few feet. At 4kHz the average fifteen is down 20dB at 45 degrees off-axis, compared to 10dB for the average ten. Of course if you put two tens side by side their dispersion is halved, so with that configuration they work no better off-axis than one fifteen anyway.

[quote]Really, none of these generalisations apply to modern cabs. But a lot of old cabs are still being made[/quote]They didn't apply to vintage cabs either. If they did then all cabs loaded with tens would sound the same, as would all cabs loaded with twelves, fifteens, etc., and we could weed out 98% of the cabs out there as unnecessary duplication.

The only factor purely attributable to cone size is dispersion. Everything else is based on driver specs. Well explained here:
[url="http://www.eminence.com/resources/data.asp"]http://www.eminence.com/resources/data.asp[/url]

[quote name='Musky' post='1051102' date='Dec 7 2010, 05:24 PM']Ampeg moved most of their production to Vietnam over two years ago now. I've not noted any negative comments about reliability with the new stuff, but then again I can't say I've really been looking for them.[/quote]
Word is the gear is OK, but mismanagement by LOUD may result in their bankruptcy, and Ampeg is currently on the block.

[quote name='Mr. Foxen' post='1045155' date='Dec 2 2010, 09:51 AM']Basically, the box probably doesn't suit the blue driver that well, it will probably suit a neo even less[/quote]Not necessarily. What specs I've seen of Blues show them to have such high Qts and Vas that they can't possibly work well in a smaller box. Or even a large one, for that matter. Many neos have far lower Qts, and more significant lower Vas, than even good drivers of prior generations, allowing them to work very well in smaller cabs. You'd want to model a few to see what works best in the cab in question, of course.

[quote name='Phil Starr' post='1044858' date='Dec 2 2010, 06:37 AM']Have a look in Dickason or a look at Gunther J Krauss, AES Mar1990. "Low frequency Transient Response Problems in Vented boxes".[/quote]
We've gotten a fair bit along since 1990. The very notion of different alignments (second order Bessel, second order Butterworth assorted Chebychev, QB3, BB4 etc) has been rendered obsolete. They date to the days of hand calculation; with modern software an infinite number of 'alignments' are easily realized, including vented which virtually duplicate sealed within a desired passband.
[quote]I am hoping that you can add to the debate with your experience of how these theoretical problems work out in practical situations.[/quote]
I have no time for debating, I'm too busy designing speakers. I offer the benefit of my professional expertise. Accept it or reject it as you see fit.

[quote name='wotnwhy' post='1044990' date='Dec 2 2010, 08:07 AM']are the eminence gamma 15's one of the recommended drivers?[/quote]
It would work, but with only 3mm xmax the Gamma 15 is marginal for electric bass usage.

[quote name='4 Strings' post='1044469' date='Dec 1 2010, 06:07 PM']The Thumpinator sounds great but for that price I could buy a pretty good speaker.

Is there a cheaper way to hit the rumble? If I wanted to put a cap in line I could solder something to the crossover board.

Any ideas on values etc? Also, would it be in parallel across the speaker?[/quote]
A cap alone won't work, you need at least cap and coil, and the price would be far more than a Thumpinator.

[quote name='Phil Starr' post='1043367' date='Dec 1 2010, 04:27 AM']Clearly sealed cabs offer better transient response and ... with a given driver, smaller size. The ports create problems of wind noise and manufacturing spreads in drive units mean that unless each driver is tested individually the tuning is a bit hit and miss.[/quote]That's the conventional wisdom, but it's not true. For every driver where that scenario does apply you'll find six where it doesn't. IME the only drawback to a vented box in general is the potential for driver over-excursion below the intended passband, and that's cured with a couple of capacitors in the signal chain to limit the LF bandwidth of the amp.
[i]"would that be where sfx's Thumpinator would come in handy?"[/i] Or that. Not mentioned yet is that, while a sealed cab naturally controls below bandwidth excursion, it does nothing to relieve the amp of the load that amplifying below bandwidth content creates. Even with a sealed cab the sound will be cleaner and the amp will have more headroom when below bandwidth content is filtered.
[quote]why shouldn't another designer exploit the same things in developing a sealed design?[/quote]The main obstacle is the lack of suitable drivers.

[quote name='Phil Starr' post='1037460' date='Nov 26 2010, 04:50 AM']I've found that spurious sounds from sources other than the strings (such as banging the guitar) can creep into the signal chain and cause some alarming excursions with some set ups.[/quote]
The downside of a vented cab is that excursion rises below the tuning frequency, and below bandwidth string thump noise can be a major problem. That's usually compensated for by a high pass filter in the amp, most have them, but not all. This thread explains:
[url="http://www.talkbass.com/forum/showthread.php?t=714170"]http://www.talkbass.com/forum/showthread.php?t=714170[/url]

With sealed cabs excursion decreases as frequency decreases, so high passing is seldom required. But sensitivity and therefore output also decreases, so it's not the best route to eliminating below bandwidth noise and driver over-excursion.

[quote name='LukeFRC' post='1041797' date='Nov 29 2010, 06:11 PM']ashdown heads.... how were the speaker cables plugged in? I found this too.

Plug both cabs into a socket on the amp..... and the volume drops.

Plug one speaker into the amp, then daisy chain the other cab in, and it will be louder.[/quote]
The amp outputs were either series wired or mis-wired with inverted polarity. The new G-K MBE210 combos came from the factory with the extension speaker jack reverse-polarity, so it does happen.