Need to replace a 12" bass cab speaker... What one do i get

[bob p]

Thanks. I guess this is all about not wanting to carry a refrigerator.

[bob p]

you know, i can't say that the quest for diminutive speaker cabinets makes all that much sense to me -- to get the size reduction you have to trade off efficiency. and the result is that you need obscene amounts of amplifier power to drive the efficiency-deficient cabinet to an acceptable SPL. the end result is that people start complaining that an amp like their 500W Ampeg pf-500 runs out of gas when they turn the master up past 12:00. invariably, the manufacturer tells them that they're abusing the equipment, and that they either need to buy more watts or more speakers. people who don't understand what's going on blame the manufacturer for selling them a bad amp. then when the threads get started, you get contributions from people who don't understand the principles of log taper ports who complain that the amp is poorly designed. i saw all of this transpire today in a thread at talkbass when someone got a response from Ampeg about the reliability of a Class-D Portaflex head:

Ampeg answers PF-500 question - TalkBass Forums

"At this point in time, the chances of one failing on you are less than 1%. I have personally been investigating many threads and have been seeing peoples settings. Most of the time they are running the amp at its limit and expect to go far beyond that. If you set your gain correctly, don’t go crazy with EQ, and do your best to keep the master no higher than noon. You will be OK. As a general rule of thumb, if you need to turn your bass amp past 12:00-1:00, then you need more power and or speakers. This is a 500 watt amp and no more than that. Many users want it to sound like a 1200 watt 4 PRO and it just isn’t capable.

Keeping the limiter on and properly using the compressor will also help to keep your amp safe."

The overwhelming majority of end-users responded by bashing ampeg.

it's unfortunate that end-users don't seem to understand that there is no free lunch. they have to choose between efficiency, size, & LF extension, and when they can't have it all, some people blame the manufacturer for producing garbage. I think their expectations are unreasonably high, as a Portaflex is supposed to be a small amp. it seems that people just don't seem to understand that under the new inefficient speaker paradigm, a 500W portaflex is a small amp.

unfortunately, the small/inefficient cabinet paradigm seems to create as many problems as it solves. sure, you don't have to carry a giant cab, but to make the cab work you have to drive it with a kilowatt of power, and the guys who have 500W amps start to complain that the amp isn't any good when driving the speaker load. worse yet, you have to be more careful today when it comes to matching a head with a cabinet -- you won't get far driving these inefficient cabs with any old-school "low power" amp. Another potential outcome might be that your small cab that sounds OK at low SPL might start to sound bad at high SPL when you drive it like hell with a kilowatt of power and push it to it's physical limits in a quest for SPL.

what makes matters even worse for a guy like me (who focuses on old-school amps with "conventional" amounts of power and efficient speakers) has to be really careful when shopping for a used cab. pairing-up a modern low-efficiency cab with a low-power tube head could end up having a rig that's just too quiet.

[RudeBoy]

... What im looking for is what 12" bass driver i should look at buying. I quick look online and i can see they are all 300-400watt
An old friend of mine (RIP) once told me that a Driver operates best when its being Pushed to its max.ie 100watt amp with 100watt speaker....Is there any truth in that?

Whats a good bass driver to get. any you bassist can recmd? I play mostly 60s/70s Bluesy rock with P Bass and Jazz and my trusty old EB3...

Ported or sealed? What is the internal volume of the candidate cabinet? Would you be willing to add a port and/or retune? What is the maximum power you expect to deliver to the driver?

[Randall]

Also today we have 900w amps in 4-5 lb packages, with XLR outs that can feed into 2Kw powered speakered PA systems that can add more bottom if needed. I don't think efficiency is as important as it used to be. Kinda like how RAM used to be.

[Steve Conner]

I'm aware that I might be treading into audiophile horn territory, but here goes anyway...

I think the new compact bass cabinets are all very well, but a physically bigger cabinet is always going to give a bigger, clearer sound. My reasoning is:

If a small cone wants to move a lot of air, it has to use a long excursion. All speaker motors and suspension systems are non-linear to some extent, so the more excursion you ask of them, the more distortion you get.

A compact speaker's low efficiency means far more heat generated in the voice coil for a given SPL. The resistance of copper increases with temperature, so you get a built-in compressor that you might not want.

Finally, a compact speaker system needs so much power that it more or less rules out tube amplification for rock gigs.

These are the same arguments that some audiophiles use to justify massive horn-loaded systems in their living rooms. Of course the disadvantages are relative and quickly get less important when you, say, move to a top floor apartment with no lift.

Finally, if you've ever wondered how small you could go...
http://bowlusblog.blogspot.co.uk/200...-shootout.html

[J M Fahey]

Nice thread

Steve Conner
I think the new compact bass cabinets are all very well, but a physically bigger cabinet is always going to give a bigger, clearer sound. My reasoning is:
If a small cone wants to move a lot of air, it has to use a long excursion. All speaker motors and suspension systems are non-linear to some extent, so the more excursion you ask of them, the more distortion you get.
A compact speaker's low efficiency means far more heat generated in the voice coil for a given SPL. The resistance of copper increases with temperature, so you get a built-in compressor that you might not want.

That's the point.
To which I add: those big heavy *long* (to get linear excursion) voice coils + thick heavy cones + tons (ok, grams ) of heavy Epoxy to hold everything together mean *mass* in a moving part: slow to start moving/slow to stop = no punch and definitely no highs.
So those compact modern cabinets add horns .
Which start "too high", speakers stop "not high at all", you have a huge hole in the middle.
The Bass sounds killer on its own , specially at the shop .... and gets drowned by guitar/drums at gigs.

Plus some Musicians are crazy: I *often* see bands where the guitar player uses a 4x12" (because it's a Guitar God classic, so he gets the same) and the bass player has a 1x15" (nowadays 2x10" are becoming popular) *combo* (not even separate head/cabinet).
What were they thinking?

I couldn't care less about the "brand" it has silkscreened nor that it's "500W Class D".
Of course, the *amp* is not the problem; if they were driving an 8x10" with it the Earth would shake.

bob p
you know, i can't say that the quest for diminutive speaker cabinets makes all that much sense to me -- to get the size reduction you have to trade off efficiency. and the result is that you need obscene amounts of amplifier power to drive the efficiency-deficient cabinet to an acceptable SPL. the end result is that people start complaining that an amp like their 500W Ampeg pf-500 runs out of gas when they turn the master up past 12:00. invariably, the manufacturer tells them that they're abusing the equipment, and that they either need to buy more watts or more speakers. people who don't understand what's going on blame the manufacturer for selling them a bad amp. then when the threads get started, you get contributions from people who don't understand the principles of log taper ports who complain that the amp is poorly designed. i saw all of this transpire today in a thread at talkbass when someone got a response from Ampeg about the reliability of a Class-D Portaflex head:
Ampeg answers PF-500 question - TalkBass Forums
Quote Originally Posted by Ampeg
"At this point in time, the chances of one failing on you are less than 1%. I have personally been investigating many threads and have been seeing peoples settings. Most of the time they are running the amp at its limit and expect to go far beyond that. If you set your gain correctly, don’t go crazy with EQ, and do your best to keep the master no higher than noon. You will be OK. As a general rule of thumb, if you need to turn your bass amp past 12:00-1:00, then you need more power and or speakers. This is a 500 watt amp and no more than that. Many users want it to sound like a 1200 watt 4 PRO and it just isn’t capable. Keeping the limiter on and properly using the compressor will also help to keep your amp safe."
The overwhelming majority of end-users responded by bashing ampeg.
it's unfortunate that end-users don't seem to understand that there is no free lunch. they have to choose between efficiency, size, & LF extension, and when they can't have it all, some people blame the manufacturer for producing garbage. I think their expectations are unreasonably high, as a Portaflex is supposed to be a small amp. it seems that people just don't seem to understand that under the new inefficient speaker paradigm, a 500W portaflex is a small amp.
..... your small cab that sounds OK at low SPL might start to sound bad at high SPL when you drive it like hell with a kilowatt of power and push it to it's physical limits in a quest for SPL.

Again quite to the point.
When everybody around here started day dreaming about "real Ampegs" , which also were compact and inexpensive, (PF500), I started worrying it would hurt or kill the sales of my meat-and-potatoes B300, which usually is mated to a 4x10" or a two by 15". (Never ever a single 15", simply it's not enough, not even if it's "1000W", "Neo" or whatever).

After the initial scare, I sleep like a baby again.
The regular 300W/4x10" one beats any 2x10"/single 15" it's met with the exception of the very good SWR 2x10" (¿Mini Goliath?) which has 2 *VERY* good PAS speakers and a horn, probably OEM made by Fostex (it looks like it) .... and it's a 350W rated cabinet, which often is destroyed by people driving it with a big Hartke (3500 or larger) / SVT Mosfet / GK700 / Eden 500.
What are they thinking?
I get them with open coils/a roll of burnt wire inside the magnet/a thumbnail sized hole in the kapton or fiberglass former.

And for the guys who wanted more power, thinking that "500W Class D" (the new standard) is louder than 300/350W Class AB , I initially made a 2 x 300W head but then, for a guy who couldn't afford a doubled head and doubled cabinet complement, I made a somewhat larger 4 x 12" *fat* cabinet (I had to measure a couple typical home doors to make sure it went through) ..... it works like a charm.

So, as they say at the car races: "there's no substitute for cubic inches".

Which does not mean cabinets *have* to be heavy, Neo magnets and light structural cabinets can save up to 50% of weight, a lot.

[Steve Conner]

I'm looking forward to carbon nanotube voice coil bobbins wound with carbon nanotube wire. They should be super-light and impossible to burn up since the whole thing is already made of carbon.

[J M Fahey]

I'm looking forward to carbon nanotube voice coil bobbins wound with carbon nanotube wire. They should be super-light and impossible to burn up since the whole thing is already made of carbon.

Following the same reasoning, I offered my girlfriend a ring with a little piece of coke on it, saying it's actually the same as a diamond, both are 100% carbon.
She married somebody else

She got so angry that she also told me my **** was a nano tube, go figure

[RudeBoy]

...So those compact modern cabinets add horns .
Which start "too high", speakers stop "not high at all", you have a huge hole in the middle.
The Bass sounds killer on its own , specially at the shop .... and gets drowned by guitar/drums at gigs....

There is a certain class of modern, sort of high end bass guitar cab being made now that uses a high xmax sub woofer crossed over to a cone mid driver around 800 Hz. Some have a tweeter above that. The crossovers are more complex than was typical in previous designs. There is no hole in the response. Using neo drivers and 12mm plywood they are light weight. Though thermal compression issue is still a factor, the designs can handle a few hundred watts before excursion limiting the driver.

I built one using a Eminence 3012LF crossed over to an 18sound 6"mid in a 2.2 cuft box using Okoume 12mm plywood. It weighs 36lb completed and works well enough with about 275W of drive. After considering the complication of its design and test, and the discovery that I don't actually play with much stage volume, were I to do it again I would make a cabinet with a single Faital Pro PR12300. It has decent efficiency and upper extension (99dB/4kHz), and the lower extension would be adequate for my playing style as well (no drop tuning). I would have saved many dollars, many hours, and perhaps a few pounds in the finished design.

[bob p]

Finally, if you've ever wondered how small you could go...

How about the new 5 kW Fender bass amp? Ultra-compact. Ultra-portable.

[bob p]

on a more serious note:

If a small cone wants to move a lot of air, it has to use a long excursion. All speaker motors and suspension systems are non-linear to some extent, so the more excursion you ask of them, the more distortion you get.

A compact speaker's low efficiency means far more heat generated in the voice coil for a given SPL. The resistance of copper increases with temperature, so you get a built-in compressor that you might not want.

I was talking to a subwoofer designer about these topics, not long after he lost a patent lawsuit on one of his designs. Our discussion mirrored your concerns.

Sometimes subwoofer designers cheat. They resort to dirty little tricks like adding mass to the drivers, knowing that it causes distortion, and not really caring about it because distortion in LF bass content is very difficult to notice with the ear. Compression in XLF subwoofer content is also something that most listeners can't recognize. The result is that these tricks add up to kilowatt powered subs that have really nasty distortion specs, but provide XLF performance that people tend to oogle about. The embodiments are sonically impressive, but they are most definitely not HiFi.

One "problem" that I've recognized with the trend toward compact bass cabinets is worsening distortion that you CAN hear. Every time I hear a compact rig that's cranked up to the point that it "growls", I find myself thinking, "That guy's speakers are distorting."

Some guys like the tone of a compact rig just because it distorts the way it does.

[bob p]

These are the same arguments that some audiophiles use to justify massive horn-loaded systems in their living rooms.

Check it out -- world's largest horn. *Sixteen* 18" drivers.



ROYAL DEVICE Hi-Efficiency Loudspeakers Audiophile speaker systems High fidelity systems Sistemi di altoparlanti hi-end HiFi ed Alta Efficienza Lautsprecher Diffusori acustici stereo Enceintes acoustiques

[loudthud]

There is an interesting design called the Double Chamber Reflex. It works amazingly well, I tried it with a JBL D140 and a University C15W. I thought is was patented, but I can't find any reference to that now. I built it in a 2x12 Bassman cabinet.

One article (pdf) from an old JBL engineer can be found here: Augspurger Double Chamber Reflex w/ JBL D216

There is another article in Speaker Builder #3 (March 1980). Couldn't find it online. In that article the builder used a pair of JBL 10 inch drivers (D110?) and used it for bass guitar. David Weems also featured it in one of his books.

There is a little bit of additional info in this thread on diyaudio: article about double chamber speaker enclosure - diyAudio

[J M Fahey]

There is an interesting design called the Double Chamber Reflex. It works amazingly well, I tried it with a JBL D140 and a University C15W. I thought is was patented, but I can't find any reference to that now. I built it in a 2x12 Bassman cabinet.

Interesting article.
I don't think it works the way he says it does, there's a couple holes in his explanation (no pun intended), as in not explaining the 2:1 chamber relationship which he pulls out of the blue, whatever does the internal inter-chamber tube, because I think it does not affect speaker coupling by the large chamber vent, which *always*vents freely to the outside, etc. , *but* that I don't understand it does not mean it doesn't work, even more based on your experiment, so whenever possible I'll build a double chamber 2x10" bass cabinet and experiment.

Of course, since I'm a boring Engineer who believes in measurements and side by side tests, I'll also build another, same size and external vents, but with no internal wall (so in theory both must have same deep bass response) and switch back and forth, both with pink noise and an actual Bass player to see whether it works as advertised.

I would expect (from the article description) same deep bass but much "fuller" sound .

Thanks for the ideas and experiments

[eschertron]

Interesting article.
I don't think it works the way he says it does, there's a couple holes in his explanation (no pun intended), as in not explaining the 2:1 chamber relationship which he pulls out of the blue, whatever does the internal inter-chamber tube, because I think it does not affect speaker coupling by the large chamber vent, which *always*vents freely to the outside, etc. , *but* that I don't understand it does not mean it doesn't work, even more based on your experiment, so whenever possible I'll build a double chamber 2x10" bass cabinet and experiment.

Of course, since I'm a boring Engineer who believes in measurements and side by side tests, I'll also build another, same size and external vents, but with no internal wall (so in theory both must have same deep bass response) and switch back and forth, both with pink noise and an actual Bass player to see whether it works as advertised.

I would expect (from the article description) same deep bass but much "fuller" sound .

Thanks for the ideas and experiments

The author states the 2:1 relationship is based on his criterion to design the Helmholtz resonator (the smaller chamber) to be tuned an octave above the larger chamber. Personally, I'd design my acoustic resonating chamber to complement or correct the frequency response of the driver, and allow the size of the larger chamber to dictated by the overall goals of the cabinet design.