Bill Fitzmaurice

[quote name='Balcro' timestamp='1506262963' post='3377399'] Check the label on the side of the Deltalites and the 15"unit. It may make the mating of the 1x15 and the 2x10 even more impracticable. [/quote]Not when bi-amped.

[quote name='xgsjx' timestamp='1506095062' post='3376467'] Though to answer your question, it's 3db. at a really low volume, you will hear a difference, but at normal playing volumes, it's a negligible amount. [/quote]3dB is audible, but not significant. If you add a second cab that will give you an additional 6dB, without touching a knob, and that is significant. But if you have a 4 ohm cab chances are you can't add a second cab, which the the #1 reason why you shouldn't consider a 4 ohm cab. #2 is that in the vast majority of cases the limiting factor on speaker output isn't power, it's driver excursion. If a 4 ohm and 8 ohm driver have the same excursion limit they also have the same maximum output. FWIW loudspeaker engineers seldom consider watts at all, while volts are key.

[quote name='Maude' timestamp='1506154448' post='3376734'] Wondered about the option of an 8ohm single speaker cab that you could flick a switch on that would put an 8ohm resister in giving a 4ohm load to the amp to get the most from the amp.[/quote]You could, and half of what the amp produced would be burned off in the resistor. It's as logical as driving with your brakes always on so you can get the most power out of your engine. [quote]I know it's pointless, but many pointless things have been made and sold. [/quote]And elected...

The power handling required of said resistor makes it impractical. That's why you don't see it done. Besides, you should never need more than two cabs, and if they're both 8 ohms there's no problem running one or the other or both. OTOH buying a 4 ohm cab is usually a mistake, unless it's large enough that you'd never need a second cab.

Solid wood is not a suitable material for large speakers. I'll use it for hi-fi speakers where the smallest dimension is no more than eight inches, but not for any professional cabs.

[quote name='aitkenaudio' timestamp='1506005715' post='3375840'] those are the two best plans you can get but if you wanna keep it simple the tl606 design is tried and tested [/quote]The TL606 came out forty years ago as a first generation T/S design, crafted around drivers that haven't been produced in 15 years, constructed with building techniques that haven't been used for even longer than that. Tried and tested yes, but also old and tired.

[quote name='Conan' timestamp='1506005186' post='3375831'] But the amp will only produce its "full power" (300W @ 8 ohms, or 500W @ 4 ohms) if it is run flat-out with all controls maxed. How many of us ever do this? [/quote]That, plus the cab power rating doesn't necessarily reflect how much power it can actually make use of before the drivers run out of excursion. More often than not that's at less than half the rated power. Also, to sound twice as loud requires ten times the power. The flip side of that is at 1/10 the power it doesn't sound 1/10 as loud, it sounds half as loud. In short, the quest you so often see of "I want to get all of the watts out of my amp" is usually at best misguided, at worst delusional.

Grammas claim to fix something that isn't broken. Cabs don't cause stages to vibrate, resonant stages cause cabs to vibrate. Preventing that doesn't require an expensive piece of kit, a piece of yoga mat is all you need.

[quote name='Ghost_Bass' timestamp='1505906766' post='3375098'] I do notice loss of the bass coupling but i gain definition and can lower the volume. [/quote]At that height there's no loss of coupling to notice. What you will notice is being able to better hear the mids and highs, which can subjectively seem like a loss of lows.

[quote name='Jack' timestamp='1505847881' post='3374771'] But if we took a driver out, filled in the gap and then ported it, we'd have a 66l, ported 1x10" cab? [/quote]Since the OP intends on bi-amping with a 1x15 for the lows and the 2x10 for the mids and highs there's no reason to change the 2x10 from what it is. If he wanted to spend some $$$ to create a useful 2x10 or a pair of 1x10 then ported is the only way to go with his tens, but he doesn't want to.

Where coupling is concerned that happens when the cab is less than 1/4 wavelength from a boundary, be it floor or wall. 1 meter is 1/4 wavelength at 85Hz, so you won't lose low end coupling with even a tall stand.

[quote name='B.Flat' timestamp='1505817955' post='3374482'] Thanks again Bill, but tell me as the volume per chamber appears to be around double the Eminence advised max [/quote]That's how small a cab they may be used in, not how small they must be used in. [quote]wlll a port not have any beneficial effect over 100hz?[/quote]None.

I usually have my 1x12 on the floor, but tilted back so that I'm directly on axis with it to hear the mids and highs. If the stage is so small that I can't tilt it back enough I put it on a stand to get it up near ear level.

If you're using it with a 15 to handle the lows leave it sealed, cross it over between 100-150Hz.

The 2510 shouldn't be used in a sealed cab, the specs aren't suitable. Your f3 will be around 95Hz. That's fine for guitar, NFG for bass. A 33L per driver cab is much too small for the 2510. The ideal volume is 60L per driver, and that's not inclusive of the port. You can get a good result with as little as 45L per driver, but again, that's net, not including the volume of the port. In short, the cab size you have would be suitable for one 2510, but not two.

I cannot, because an easy calculation won't tell you port velocity. If it's too high, because port area is too small, you'll have chuffing noise. If the port area is larger than required to prevent chuffing the ports will be larger than necessary, making the cab larger than necessary. The speaker modeling software I use for ported cabs is WinISD 0.7.950 http://www.linearteam.org/

A 102mm port has an area of 8167 square mm, two 50mm ports a combined area of 3925 square mm, so the answer is no. For the same Fs the 50mm ports would be much shorter. However, they also might chuff. Your speaker modeling software should show you port velocity at maximum excursion, which you want no more than 20 meters per second within the cab pass band. It will also show you what port area and length you can get away with to meet that requirement.

[quote name='alexclaber' timestamp='1505310789' post='3370935'] There's definitely a bigger issue in North America because they only have half as much voltage coming out of the wall. Yay for proper 220V+ power (we have the most here in the UK). [/quote]It's not an issue where bass amps or club size PA is concerned, nor for that matter with pro-touring sound, where the power amps typically run on 220v.

A fan would make the amp position irrelevant, whereas convection cooling can require specific orientation of the amp to function.

The possibility exists that it could reduce the effectiveness of the amp's cooling mechanism, especially if it's passive and not fan driven.

[quote name='Kevin Dean' timestamp='1504770251' post='3367123'] But He doesn't have this problem with my front ported cabs , To me it's obvious that the low end would also be louder to him with the rear port . [/quote]And again, the science is never wrong. As I already noted the main reason why some cabs are rear ported is that they're too small for the ports to fit on the front. Smaller cabs have higher Q than larger cabs, resulting in boomy response, and that's why what he hears with front versus rear ported cabs is different, not the port location. The difference will be less obvious to you, as the boom is masked by the mids and highs that you can hear because you're in front of the cab, and he can't, because he's behind it.

[quote name='Kevin Dean' timestamp='1504723659' post='3366923'] If I've had my rig in front of a drummer Ive had complaints when using rear ported cabs that the lows were too loud muddy sounding . [/quote]Look at the polar chart I posted. Of course it's muddy when the cab is in front of him, all he can hear is what's below at best 300Hz. To his side is better, but if he's going to hear the entire bandwidth you must either be in his monitor or you need two cabs, stacked vertically, with the lower cab aimed at him, the upper cab aimed at you. The science of audio always works, whether you believe in it or not. The problem when you don't learn the science is that when issues arise you won't know what causes them, so you can't know how to fix them.

[quote name='Ghost_Bass' timestamp='1504710670' post='3366821'] I stand by my words, having the port aimed to the front gives something more to the sound [/quote]Watch this, particularly from the 1:00 marker to the 5:10 marker, although almost every member here would benefit from watching all of it: [media]http://www.youtube.com/watch?v=BYTlN6wjcvQ[/media]

[quote name='Ghost_Bass' timestamp='1504690139' post='3366542'] Isn't it possible that those freqs might reflect inside the cab and leave through the port along with the bass and that may translate in to [i]something more[/i][/quote]It is possible, with a cab that's defective. One of the reasons why well designed and built cabs have internal damping is to prevent that. A few years back G-K brought out a line of cabs that were not damped, and poorly braced. They made the claim that they sounded better without damping. That claim was revealed as piffle when owners of them added bracing and damping and found they sounded much better after so doing. Not surprisingly Generation II of that line of G-K cabs were better braced and internally damped. By the same token there have been rear ported cabs that placed the ports where midrange cone radiation could make its way directly out the port. That as well is a design defect. [quote] Don't give me text book answers please, i'm not a sound engineer, but i'm a very practical person and this makes scense to me [/quote]Where the behavior of sound is concerned text book answers are a necessity, because what intuitively makes sense is usually wrong. Besides, you're a bass player. You're supposed to be the brains of the band. There is a different position for blokes who lack any clue as to how the gear they use to make a living with music works: guitar players.

[quote name='Ghost_Bass' timestamp='1504626354' post='3366161'] imagine a kick drum, stand behind it (next to the drummer) and listen to the sound. Now move to the other side, in front of the kick port, and listen to it. Isn't it different? [/quote]It is, but not in the lows. This is a polar pattern of a typical large speaker: The output pattern is 360 degrees to 80Hz. Port output is centered at the speaker tuning frequency, which generally runs between 40 and 50Hz. You will hear a difference with any source based on where you are, but it won't be in the lows.