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Tuned custom Bass Cab build?

K

kingwilliam

Apr 30, 2012
3
0
#1
Hi, firstly I'm new here, did a little search couldn't find anything already going, so have started a new thread.

Ok, I'm a music Tech BA student, completing my dissertation, and any help would be grand :)

I've designed and built a custom Bass cab' with the intention of making it 'Tuned' (in a fashion) to the four fundamentals of the a bass guitar (This being the 4 open strings) Now, me and a few educated guys have established that in theory, using the correct length/diameter bass-reflex tubes, in relation to the cab volume etc is should be achievable to enhance the freq' of the fundamentals, and increments of.
Now, I'm no expert in said matters, as I'm in education, but will believe this may work. (At least if it's doesn't I've had a good go at testing the theory ;)

Now, lets assume this works. My question will be, why has no one though of this idea? Or...perhaps they have, and it is unsuccessful. Or...no one has though of it.

I understand this all sounds pie-in-the-sky, but any debate on this would actually be of great help.
Can't beat some real time market research
As mentioned, this has been constructed, just not tested as yet....:hyper:

Many thanks for letting post here.
 
#3
I'll take a shot as to why it hasn't been tried before.

Why would you want to tune the cab to the open strings? I would think that open strings count for about 10-25% of the notes a bass player plays on a given song (depending on bass player and song).

Maybe I am missing the point, so enlighten me as to why this is an advantage.
 
#4
kingwilliam said:
Hi, firstly I'm new here, did a little search couldn't find anything already going, so have started a new thread.

Ok, I'm a music Tech BA student, completing my dissertation, and any help would be grand :)

I've designed and built a custom Bass cab' with the intention of making it 'Tuned' (in a fashion) to the four fundamentals of the a bass guitar (This being the 4 open strings) Now, me and a few educated guys have established that in theory, using the correct length/diameter bass-reflex tubes, in relation to the cab volume etc is should be achievable to enhance the freq' of the fundamentals, and increments of.
Now, I'm no expert in said matters, as I'm in education, but will believe this may work. (At least if it's doesn't I've had a good go at testing the theory ;)

Now, lets assume this works. My question will be, why has no one though of this idea? Or...perhaps they have, and it is unsuccessful. Or...no one has though of it.

I understand this all sounds pie-in-the-sky, but any debate on this would actually be of great help.
Can't beat some real time market research
As mentioned, this has been constructed, just not tested as yet....:hyper:

Many thanks for letting post here.
Click to expand...

Missing the point. Box tuning isn't about the individual frewuencies of the notes, but in general, shapes the low frequency response of the system and controls cone movement down there while providing more low frequency output over a sealed box.


Read this:

http://www.talkbass.com/forum/f15/a...overunderpowercabs-diy-techtalk-links-166225/
 
#5
Thanks for your replies. As mentioned, I am in education, and not assuming I'm correct on these matters, this i why I've come to a specialist forum.

Ok, so, I've been looking at it from a 'Harmonics' point of view.
'Harmonic frequencies are equally spaced by the width of the fundamental frequency and can be found by repeatedly adding that frequency. For example, if the fundamental frequency is 25 Hz, the frequencies of the harmonics are: 50 Hz, 75 Hz, 100 Hz etc.'
Therefore, any Fundamental will contain a range of Harmonics, IE: All the other notes. Do you think this is correct guys?
So if the Fundamental is enhanced, so will be it's harmonics, (The others notes)
I suppose another way to look at this, is why port a cab to enhance, lets say '50hz' for example, (or what ever a said cab might drive to) what benefit does that have to any notes that are played?...

As mentioned, a nice helpful debate is what Im after, to assit me in my dilemas.
Many thanks :D
 
#6
will33 said:
Missing the point. Box tuning isn't about the individual frewuencies of the notes, but in general, shapes the low frequency response of the system and controls cone movement down there while providing more low frequency output over a sealed box.166225/[/url]
Click to expand...

yes, this makes sense to me, but could it not be possible to shape the low freq' of the box to a value you chose? Such as the fundamentals? So the 'Low frequency output' is actually the figure you chose? (open strings, and the partials off)

...just a thought....
 
#9
kingwilliam said:
I've designed and built a custom Bass cab' with the intention of making it 'Tuned' (in a fashion) to the four fundamentals of the a bass guitar (This being the 4 open strings)
Click to expand...

How are you doing this? Simply using four different port lengths in the same box won't do it, as you'll still only have one tuning frequency. Run an impedance curve and you'll see what I mean.

kingwilliam said:
Now, me and a few educated guys have established that in theory, using the correct length/diameter bass-reflex tubes, in relation to the cab volume etc is should be achievable to enhance the freq' of the fundamentals, and increments of.
Now, I'm no expert in said matters, as I'm in education, but will believe this may work. (At least if it's doesn't I've had a good go at testing the theory ;)

Now, lets assume this works. My question will be, why has no one though of this idea? Or...perhaps they have, and it is unsuccessful. Or...no one has thought of it.
Click to expand...

There are at least three reasons why what you're describing is not being done:

1) Selectively enhancing the fundamental of each open string would be solving the wrong problem. All of the notes are equally important, to most bass players anyway.

2) It's not really practical to do. You'd have to use four different woofers, each in its own separate chamber, each tuned to a different frequency. The net result would approximate a low-Q resonance instead of the higher-Q resonance of a cabinet with a single tuning frequency, along with some net loss of energy due to the port outputs not adding perfectly in-phase. It is possible that, depending on the specific characteristics of the woofers you're using, this multi-chamber multi-tuning approach might sound a bit better, but with a high-quality woofer such is unlikely to be the case.

3) From a perceptual standpoint it's not the fundamentals that matter most anyway, it is the first overtones. See the thread will33 linked to in post #7 above.

What the designer does have to do is juggle tradeoffs. For instance, he has to juggle strong output in the region where he needs it the most (first overtone region) vs fartout due to over-excursion, which is most likely to happen if the cab is tuned too high but can also happen if the cab is tuned too low.
 
#11
Also, repeating something that was said earlier but the OP seems to still be missing: the four open notes ARE NOT "the four fundamentals of the bass". Those are just four out of the 80 or more fundamentals. Each note up and down the fretboard has its own fundamental, and basses nowadays may have 5, 6, 7, even a dozen or so strings. Say you have a 12-string ERB with 24 frets, that's 288 fundamentals! (depending on tuning and other particulars) And even if you cling to the old-school 4 strings and 20 frets, that's still 80, an awful lot of different fundamentals.
 
#12
bongomania said:
Also, repeating something that was said earlier but the OP seems to still be missing: the four open notes ARE NOT "the four fundamentals of the bass". Those are just four out of the 80 or more fundamentals. Each note up and down the fretboard has its own fundamental, and basses nowadays may have 5, 6, 7, even a dozen or so strings. Say you have a 12-string ERB with 24 frets, that's 288 fundamentals! (depending on tuning and other particulars) And even if you cling to the old-school 4 strings and 20 frets, that's still 80, an awful lot of different fundamentals.
Click to expand...



" cling to " ???














:D

+1...good points.
 
#13
Well, if you want to get nitpicky, there are a lot of doubles in there. Example, the D on the A string, 5th fret and the open D string will have the same fundamental and harmonics, but they'll be in a different relationship to each other in the individual frequency levels due to the different string guage and it's vibrating over a different length, but good points anyway.
 
#15
Ports in cabinets aren't there to tune the cab to any musical note or fundamental. They are there to tune the cabinet's frequency response in relation to the frequency response of the driver (speaker) to control the output curve of the system. The SYSTEM is the combined components working together.

Once you put a speaker in a box you will get an interaction of the speaker and the box - BTW the box is already a system comprised of the physical box, it's materials and its bracing, and the volume of air contained therein.

So you don't tune the system to "E" because that's the lowest note on the 4 string bass, you tune it to control the resonance of the system to gain low end extension and tame uneven responses of the loudspeaker system. Tuning to the instrument that will be played will pretty well guarantee that the overall system response will be horrid.

Oh, just in case you are thinking it's just my opinion, I was the designer and builder of high end audio speaker systems. Not any more though. Rather play than listen......
 

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