cabinet frequency response

[Arjank]

If you go for a shorter gap with higher flux within the gap you'll get lower inductance (less metal near the coil) and less of the excursion will be reliant on the fringe field where the inductance variation is largest. Using a longer gap will push the inductance up and increase the variation with displacement so is more likely to need shorting rings to bring the THD back down.

You might guess that much of my R&D time over the last couple of years has been on the driver side of things!

+1

Well explained.

 

[AstroSonic]

Seeing the BL vs excursion curve of a motor (you can model it accurately with FEA) can tell you a lot about how a speaker will perform at high power. The other parts of the puzzle are the suspension non-linearity and the port non-linearity - all three aspects have to be considered to get optimum performance.

+1

It would also be helpful to have thermal compression curves as well. This will relate to both power handling and BL loss (which is a function of both excursion and voice coil resistance). This will be particularly important when compression is being used (by the musician, in the electrical signal chain).

Of course, for voiced cabs, someone with a good ear is required.

 

[alexclaber]

It would also be helpful to have thermal compression curves as well. This will relate to both power handling and BL loss (which is a function of both excursion and voice coil resistance). This will be particularly important when compression is being used (by the musician, in the electrical signal chain).

Yes, during the past few years the importance of thermal compression has become more and more clear to me - and it goes a long way to explaining the popularity of 4x10" and 8x10" cabs for such a long time. Yes, they tend to be sensitive but a good 6x10" would be no more sensitive than a comparable 2x15" from the same era. However, lower thermal power handling of the 2x15" due to reduced voice coil area would cause power compression to be greater so the cab's voltage sensitivity is diminished at high SPL.

The solution is to have big voice coils and well designed cooling systems when you have fewer speakers and then you can bring the thermal compression down - and for instance, make a 2x12" that can match a 4x10" on that front, as well as beat it on all others!

I'm not sure it's a great idea publishing that data for bassists though - that amount of depth to the tech stuff can be a massive distraction from actually playing music...

 

[svtb15]

Thank you.. It has always been one of my fave 115 cabs... I still have one and a custom Double 115 that i got from them in the early 80s.. Just too big to move by myself these days..

That cab is approx 160liters, pretty much optimal for the 3015LF, it'll work for sure. I guess the tuning will be around 40hz.

 

[12bass]

That cab is approx 160liters, pretty much optimal for the 3015LF, it'll work for sure. I guess the tuning will be around 40hz.

FWIW, this response concerns the 3015LF, while svtb115 had asked about the 3015, which is not the same driver.

 

[svtb15]

ooopsss you are right ^

 

[Arjank]

ooopsss you are right ^

damn, my fault!

well, the ideal cab for the 3015 is approx 120 liter but it will still work well in 160liters. There's allways a room for playing with these volume values. The larger cab wil probably give the 3015 a bit more oomph in the 35hz - 50hz region in return it will sound a bit more muddy(but not by much).

 

[AstroSonic]

Yes, during the past few years the importance of thermal compression has become more and more clear to me - and it goes a long way to explaining the popularity of 4x10" and 8x10" cabs for such a long time. Yes, they tend to be sensitive but a good 6x10" would be no more sensitive than a comparable 2x15" from the same era. However, lower thermal power handling of the 2x15" due to reduced voice coil area would cause power compression to be greater so the cab's voltage sensitivity is diminished at high SPL.

The solution is to have big voice coils and well designed cooling systems when you have fewer speakers and then you can bring the thermal compression down - and for instance, make a 2x12" that can match a 4x10" on that front, as well as beat it on all others!

I'm not sure it's a great idea publishing that data for bassists though - that amount of depth to the tech stuff can be a massive distraction from actually playing music...

Thermal compression: Yes, that's the idea. It may be better to distribute the thermal load amongst multiple drivers.

I understand what you are saying in the above post with respect to thermal compression, but the reference to cab formats (4x10, 2x12, etc.) may tend to stereotype them with respect to performance. They tend to be thought of as 'old school', using inexpensive drivers with low power handling and short Xmax, in big heavy cabinets. This is in contrast to modern cabs, employing advanced drivers (WRT thermal management, Xmax, power handling, etc.). Let's drop the 4x10 (blank by blank) terminology for a moment and think in terms of phased arrays of using advanced drivers in well braced light weight cabinets. For example, if we go with a '6-by' format, with 2 columns, with only one column active above a frequency chosen to maintain some specified beam width (and minimize driver interference), then add a line array of small mids centered between the 2 large driver columns, and connected with an appropriate crossover we will have something quite different form 'old school' multi-driver cabs. The multi-driver format allows the thermal load to be distributed as you discussed.

IME/IMO there is just something about the sound of multiple driver cabinets. It is effortless, enveloping and massive. I suspect that it has something to do with mutual coupling, greater radiation resistance (than single 'super' driver cabs) and possible the nature of the wavefront. Don't know if this will even be figured out in my lifetime, but the tone quality difference between a single small driver and multiple drivers is as real (IMO/IME) as that between cabs that reproduce the fundamental and those that only cover the second or third harmonic (and up).

The smaller cabs can sound awesome and are definitely more portable, and are great for tight performing spaces. Bottom line: they are just a way more practical playing solution for a lot of players. Still, I'll bet many would be interested in an advanced, phased array cab.

 

[AstroSonic]

damn, my fault!

well, the ideal cab for the 3015 is approx 120 liter but it will still work well in 160liters. There's allways a room for playing with these volume values. The larger cab wil probably give the 3015 a bit more oomph in the 35hz - 50hz region in return it will sound a bit more muddy(but not by much).

Per the discussion in this thread, it should not exhibit more mud due simply to its deep bass extension... provided the T/S parameters (and therefore the cab alignment) remain stable. A player still has the option of overdriving the cab for increased spl and/or the resulting tone.

 

[David Jayne]

Still, I'll bet many would be interested in an advanced, phased array cab.

ME!!!
Hell, I'd like to learn how to simply low-pass one column of drivers in my 4x10 cab. Poor man's array.

 

[alexclaber]

Thermal compression: Yes, that's the idea. It may be better to distribute the thermal load amongst multiple drivers.

I understand what you are saying in the above post with respect to thermal compression, but the reference to cab formats (4x10, 2x12, etc.) may tend to stereotype them with respect to performance. They tend to be thought of as 'old school', using inexpensive drivers with low power handling and short Xmax, in big heavy cabinets. This is in contrast to modern cabs, employing advanced drivers (WRT thermal management, Xmax, power handling, etc.). Let's drop the 4x10 (blank by blank) terminology for a moment and think in terms of phased arrays of using advanced drivers in well braced light weight cabinets. For example, if we go with a '6-by' format, with 2 columns, with only one column active above a frequency chosen to maintain some specified beam width (and minimize driver interference), then add a line array of small mids centered between the 2 large driver columns, and connected with an appropriate crossover we will have something quite different form 'old school' multi-driver cabs. The multi-driver format allows the thermal load to be distributed as you discussed.

IME/IMO there is just something about the sound of multiple driver cabinets. It is effortless, enveloping and massive. I suspect that it has something to do with mutual coupling, greater radiation resistance (than single 'super' driver cabs) and possible the nature of the wavefront. Don't know if this will even be figured out in my lifetime, but the tone quality difference between a single small driver and multiple drivers is as real (IMO/IME) as that between cabs that reproduce the fundamental and those that only cover the second or third harmonic (and up).

The smaller cabs can sound awesome and are definitely more portable, and are great for tight performing spaces. Bottom line: they are just a way more practical playing solution for a lot of players. Still, I'll bet many would be interested in an advanced, phased array cab.

I could write a ton on this, and may find the time to write some stuff, but before I do so, have you seen what we make?

 

[AstroSonic]

I could write a ton on this, and may find the time to write some stuff, but before I do so, have you seen what we make?

Alex,

Your website is a treasure trove of information on bass cabs and bass reproduction for players and for those interested in cab design and construction. The articles for Bass Guitar Magazine were really nicely done.

You have added a few more products since I last visited, and your current product line clearly reflects your design choices. Glad to see the 2-by cabs and rather curious about the 69er.

I look forward to any comments you may have.

 

[Arjank]

I could write a ton on this...

Yup, me too. I could ramble on for quite some time on these topics.
My english writing is not as good as you guys so sometimes I may write things a bit awkward so the explanation is not 100% right. Most of the speaker stuff is in my head(all the time, hahahah), I visualize it.

I allways quote Nicolas Tesla; "Before I put a sketch on paper, the whole idea is worked out mentally"
80% of a design is done in my head before I put anything on paper. The cool thing is that it works. What I visualize in my head sounds that way in real life after I build it .

 

[svtb15]

Would a BAREFACED 15 be equal in out put to my old BagEnd S15B-d deep cab...? The one one i spoke about above....
Its the deep cab 24" not the small cube thing that everyone has

 

[seamonkey]

Funny after pages of discussion there turns out to be no published data that could help you in your comparison. A few objective measurement could help anyone confirm or correct their subjective opinion on what they're hearing versus reality. If you know what you have, you can know what you want.

 

[alexclaber]

Would a BAREFACED 15 be equal in out put to my old BagEnd S15B-d deep cab...? The one one i spoke about above....
Its the deep cab 24" not the small cube thing that everyone has

At lower frequencies you're excursion limited so the Compact would have more output even though the sensitivity would be lower down there. At higher frequencies you're limited by the product of sensitivity, thermal power compression and power handling, so the Compact would have more output. The only exception would be if your amp power is on the low side.

 

[svtb15]

Thank you...
I have been looking at the Barefaced for a while. I just dont know anyone that has one...

 

[Mr. Foxen]

And neodymium magnets reduce harmonic distortion too because they're conductive, unlike ferrite magnets.

Did alnico magnets do that too?

 

[Arjank]

Did alnico magnets do that too?

Alnico is electrically conductive.

 

[alexclaber]

Thermal compression: Yes, that's the idea. It may be better to distribute the thermal load amongst multiple drivers.

Really it comes down to your voice coil area and then the mechanisms to cool that. But that's one reason why our Big Twin performs better with less powerful amps than our Big One did, despite the sensitivity being similar - the Big Twin has twice the voice coil area and therefore half the power compression at any given power input, which means you get more SPL from less power and thus even less power compression.

For example, if we go with a '6-by' format, with 2 columns, with only one column active above a frequency chosen to maintain some specified beam width (and minimize driver interference), then add a line array of small mids centered between the 2 large driver columns, and connected with an appropriate crossover we will have something quite different form 'old school' multi-driver cabs. The multi-driver format allows the thermal load to be distributed as you discussed.

Our '69er uses a similar format but with one of the 10"s as the mid/treble driver. The issue I've found with cone midranges in musical instrument cabs is that they sound clearly different to cabs without them - yes, they improve polar response but they don't do so without changing the character of the cab. You can't just go sticking mid drivers in cabs, even with really well thought out and carefully designed crossovers and expect everyone to like the end result.

IME/IMO there is just something about the sound of multiple driver cabinets. It is effortless, enveloping and massive. I suspect that it has something to do with mutual coupling, greater radiation resistance (than single 'super' driver cabs) and possible the nature of the wavefront. Don't know if this will even be figured out in my lifetime, but the tone quality difference between a single small driver and multiple drivers is as real (IMO/IME) as that between cabs that reproduce the fundamental and those that only cover the second or third harmonic (and up).

I'm not sure it's so much multi-driver cabs as cabs with a larger amount of radiating area. I believe there's also a big deal with inductance - lower the inductance and you improve the front half of the transient response. Another key part of the puzzle is the ratio of moving cone mass to airload on cone - the closer the characteristics of the cone to that of the air it's moving, the greater the efficiency of the system, the more quickly any cone resonances are damped by the air, and the more 'real' the cab tends to feel. That's easy to achieve with very big cabs with very low power handling but once you turn up loud the upsides of the greater acoustic coupling become insignificant compared to all the sonic downsides of huge distortion due to over-excursion. So if you want a cab that you can gig in loud bands and still fit in your car you need to do some careful balancing of compromises.

I'll just add that I think anyone focusing on F3, F6 and F10 without considering the sensitivity of the system and both forms of power handling is somewhat missing the point. If you have two cabs of equal size, one with 96dB sensitivity and F6 at 45Hz, one with 93dB sensitivity and F3 at 45Hz what's the difference in the low frequency ability? Then consider the duty cycle for bass guitar (and indeed all recorded music): Yes there can be big peak power down at 50Hz and below but it's rarely sustained for long. The peak power will be just as high at 100Hz but the average level will be much higher.

Further investigation shows that at very low frequencies the limiting factor is almost entirely down to excursion limitations (both speaker based and port issues). At higher frequencies the sensitivity and thermal power handling dominate. Raise the sensitivity where the duty cycle is most demanding and you lower the voice coil temperature, giving the amp more power to use. Then EQ back in the deepest lows because you have the amp power to push the cab and the excursion to handle that power down there.