Bill Fitzmaurice

[quote name='RandomBass' timestamp='1431283150' post='2769610'] Do any manufacturers state those specifications? [/quote]Barefaced.

Which has the highest excursion/driver displacement? That's what limits low frequency output. It's a bit of a trick question, since none of the listed examples tell you what their driver excursion limit/displacement is.

[quote name='Dad3353' timestamp='1431117538' post='2768051'] This is not a universal truth. Valve amps with o/p transformers need a cab connected, but most, if not all, solid-state amps are OK without. There may be[b] some, rare, exceptions[/b] I'm unaware of, of course. [/quote]Those exceptions would be transformer coupled first generation SS amps from the 1960s. They, like tubes, always have current flowing into the transformer primary, so a speaker load or a short circuit of the transformer secondary is required. With direct coupled SS if there's no speaker no current flows through the output devices and there's no problem.

Cabs don't hiss. Amps do. That's where you should be considering a change.

[quote name='robocorpse' timestamp='1430997509' post='2766664'] Would there be any sense in upgrading to HLF, or will a pair of HE do the job? [/quote]No, as that would create a chain in which the HE is the weak link. That scenario is one of the myriad of reasons why you should not mix cabs.

Get a second identical 410. Mixing cabs is a crapshoot.

[quote name='Marvin' timestamp='1430918386' post='2765920'] So does high cone excursion result in poor transient response, as implied by the 'pro' and said not to be the case by Alex Claber and Bill Fitzmaurice. Which is correct? [/quote]Note that I said that transient response isn't affected by excursion but by voice coil inductance. Some high excursion drivers also have high inductance voice coils. One could use a high excursion driver, notice that transient response was affected, and therefore conclude that it was the excursion that caused the loss of transient response. With an adequate engineering knowledge base one would not make that error. Also note that I said that musical instrument drivers don't have high inductance. Many PA drivers do. That's not an issue if the crossover from the woofer to the midrange driver occurs at a frequency low enough where the high inductance of the woofer has no effect. Well designed PA cabs, or bass cabs that use high inductance PA woofers and midrange drivers, do just that. But not all PA cabs or bass cabs that employ PA woofers are well designed.

[quote name='Sibob' timestamp='1430498850' post='2762124'] Yep, surprised it got the go ahead actually. TC Group supplies chips and drivers to a number of MI companies. Will be interesting to see how it plays out. [/quote]Probably no better those companies that were acquired by Loud Technologies. Small engineering driven companies seldom fare well once their direction is dictated by bean counters.

[quote name='Conan' timestamp='1430913167' post='2765823'] some people don't like to have their preconceptions challenged... [/quote]+1. When it's pointed out that the emperor is stark naked there is a faction who will insist that those who believe that to be true simply have not properly trained their eyes. As for the admirable auditory skills of various musicians, producers and engineers, most do the best they can with the tools that are at their disposal. Some do very well operating within that constraint. OTOH others come to the realization that sometimes what's required is a better tool.

[quote] I'm a bass player, songwriter & lyricist and (bad) singer. [/quote]No one I know of who's a good bass cab designer isn't a bass player. For that matter many of the better PA speaker designers are also bass players, Tom Danley being one example. We didn't learn the science as pure exercise in academia, we learned it because we wanted to know all of the hows and whys of how our gear worked. We didn't have to delve too far into the subject to find out that by using science we could do much better than what was already out there. In that quest the three of us, among others, have been supremely successful.

[quote name='Marvin' timestamp='1430834096' post='2765002'] Science explains what your ears are trusting. Your 'ears' and science don't live in different worlds. [/quote]+1. The beautiful thing about science is that it always works, whether you understand it or not.

[quote name='Jazzneck' timestamp='1430547688' post='2762435'] I have found that it makes no difference to my shot ears (and punters who have commented) on whether the cab is set horizontally or vertically. [/quote]It will make a differnce in the mids, and it will do so only off-axis. If you don't move from side to side on stage you won't notice it. If you don't have the cab tilted back or elevated so that you can hear the mids you won't notice it. If you don't have much in the way of mids, for instance with a raggae tone, you won't notice it either.

[quote name='xgsjx' timestamp='1430472398' post='2761690'] It depends on the 2x10 in question & how good it is at moving air. [/quote]+1. All ten inch drivers are not created equally, so neither are all 2x10s.

[quote name='alexclaber' timestamp='1430229342' post='2759200'] There's no link between high cone excursion and poor transient response - in fact the reverse is likely to be true because a driver which is operating within its linear region will have far better cone control than a driver whose voice coil is moving out of the magnetic gap on louder notes. [/quote]+1. Using the term 'slow responding' is an example of thinking within the realm of the speed of sound. If drivers operated under the constraints of typical mechanical devices this would be true. But they don't. The electromotive forces responsible for cone movement operate within the realm of the speed of light. What does affect transient response is high voice coil inductance (Le), because that is an electrical parameter, not a mechanical parameter. Very high Le drivers will have poor transient response in the higher frequencies. But musical instrument drivers don't have high Le values, nor is there any direct correlation between Le and driver size.

[quote name='jimcroisdale' timestamp='1430142810' post='2758337'] It's been a couple of years since I used Win ISD, but I have been having a look in the last hour or so, yes. :-) [/quote]When you model you need to consider not just the sensitivity charts but also the Maximum SPL chart. That's actually more important than sensitivity, as it considers sensitivity, thermal and displacement limited power handling. In the vast majority of cases you'll find ported to be superior to sealed cabs.

[quote name='jimcroisdale' timestamp='1430131211' post='2758164'] Is it fair to say that even a small cab (16x16x12in) would be better with a port then, given the use of an Eminence neo such as the Kappa/Delta/Basslite? [/quote]Have you software modeled both options? That's the first step in the design process. To be blunt, if you don't know how to use modeling software you can't design a speaker with any better result than you can playing darts while blindfolded. Through sheer luck you may make the occasional bullseye, but more often than not you'll do well to even hit the board at all.

[quote name='Stylon Pilson' timestamp='1429274337' post='2749920'] If this was a Hollywood movie, the plucky bootsy666 would build his bass cab anyway. There'd be a montage scene with lots of screwing and glueing and tolexing. And then there'd be a final climactic scene where his bass cab would face-off with one of Bill's, and blow it out of the water, and Bill would admit defeat and pass the mantle to the spunky young underdog. [/quote]This scene would be more apropos, and I'm not the one with the sword: https://www.youtube.com/watch?v=anEuw8F8cpE

[quote name='bootsy666' timestamp='1429266251' post='2749786'] If there were two sets of four speakers in this cab, both same impendance and watts, but different frequencies. Four of the the same in the centre four holes, and the other four in the top two and bottom two, with a horizontal baffle inside dividing the eight speakers into two sets of four, would it sound better? [/quote]Please don't take offense, but posing questions like this one point out why you should not be trying to design your own speaker. One must learn to crawl before learning to walk, and where the science of acoustical engineering is concerned you're still in the pram. Whatever time and money you have invested in this project should be chalked up as a loss, the cost of a learning experience. Go back to square one and read, read, read. The sources are out there.

[quote name='bootsy666' timestamp='1429121886' post='2748301'] Celestion have told me that the tf1525 is for PA and electric bass. My other option is the 1530e? [/quote]You have literally dozens, if not hundreds, of options for drivers. But before you even think about designing your own speaker you have to start with the basics of understanding how speakers work and how they're properly designed. This resource is a good starting place: http://techtalk.parts-express.com/showthread.php?219617-The-Speaker-Building-Bible

To be brutally honest, nothing about that cab configuration is as it should be. It will put out a fair amount of low end, via sheer brute force with a sufficiently large amp, but the same low end output could be realized using two good fifteens in a properly engineered cab. The midrange dispersion will be horrid. My best advice to the OP is that if you haven't bought the TF1525 yet, don't. They're supremely unsuited to electric bass. Believe me, if I coud find any basis to lend encouragement here I would, but there is none.

[quote name='chrismuzz' timestamp='1429046239' post='2747434'] Apparently you can't if your amp has a valve power stage, but I don't know why [/quote]With SS if there's no speaker no current flows from the output devices, so no harm. With tubes current flows from the tubes to the output transformer primary windings whether there's a speaker or not. As current can't flow from the transformer secondary windings if there is no speaker bad things happen.

[quote name='leonardobass' timestamp='1428414103' post='2741039'] i can't really find any reviews for this brand on that particular use. [/quote]Reviews don't matter. T/S specs and measured response charts do. With those you can accurately predict results and cab compatability. Without them you have no way of knowing what you'll end up with. By the same token, when it comes to building a cab you can't just toss a driver into a box. No matter how good the driver is if the cab isn't properly matched to it, and if the cab isn't properly constructed, it won't work well.

[quote name='yondergo' timestamp='1428242799' post='2739481'] Thanks again Bill, that's made a big difference to the plan, I'm going to look at sealing the existing 4" baffle hole and porting the sides of the cab now, once I subtracted the volume of the ports and winISD recalculated the length of the ports I was almost butting up to the back of the cab. Should have done this work earlier, probably would have decided to buy a different cab and scrap the peavey enclosure. Oh well, we soldier on. [/quote]You can keep the ports behind the grill, just add 90 degree elbows to the ducts. The effective duct length is measured on the centerline.

[quote name='yondergo' timestamp='1428132343' post='2738273'] One other concern was how much clearance I would need inside the cab where the end of the port approaches the back of the cabinet, it's looking like i'll have probably an inch and a half between the port end and the foam damping, is there any negative effect to be expected from this? [/quote]You need approximately the port diameter distance to the back of the cab, otherwise the air mass between the cab back and port entrance can add to the air mass in the port, lowering the tuning.

[quote name='yondergo' timestamp='1428095685' post='2738133'] I was hoping to use 2 4" ports, would your point about 4" ports not being suitable apply to using multiple ports or is it 4" ports in general? [/quote]There's nothing wrong with 4" ports, but that's insufficient area to use with a 15" driver. Two would be OK.