• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Isobaric cab?

#81
spwath said:
And it's worth the 15$ to get the plan instead of making one myself? I was planning on using a midrange driver, not a tweeter. Also, why not just build one myself using the dimensions from WinISD, and some internal bracing and such?
Click to expand...
I have a PhD in electrical engineering, so I have the background to understand the math and theory. I'm not a master carpenter and cabinet designer, so I while I could probably come up with my own designs I prefer to leave that to someone who is a master in that field. Also, the Simplexx 15 can be configured with either a 2000 hz tweeter or a 1200 hz tweeter crossover.
Its kind of like asking why Ford doesnt put Hemi or Vortec engines in their vehicles.
Click to expand...
They do offer more than one engine choice. :)
 
#82
Rick James said:
They do offer more than one engine choice. :)
Click to expand...

Not for free.
Yel_wink.gif
 
#83
spwath said:
Really, that high?
From what I found it said a standard bass goes down to like 50hrz, mine would go to 40. But I guess not. I'll do some comparing with my low c and a frequency generator.
But then I could probably make it smaller. Not isobaric, and sell the other woofer, or build another cab for it.
Click to expand...

Standard bass i.e. E is 41.2Hz. Low B is 30.87Hz. If you want to know harmonics just keep adding the fundamental.
 
#86
spwath said:
So then I would want a cab that goes to 40 and below.
Click to expand...
I'm sure @ficelles only meant your "standard bass goes down to like 50hrz" is actually 40.2 Hz (actually 41.2*) - he adds you can calculate harmonics by multiplying the fundamental by integers -, but the suggestion to aim for a strong (at -3 dB or higher) first overtone (AKA second harmonic) still holds: you may or may not want to have your lowest fundamentals (barely) audible (say -10dB), assuming your strings/pickups produce them at any significant level in the first place, but to shoot for having them at or over -3dB would be an extremely difficult task, with no serious pros and countless cons.


*fourty-one point two: if I feel the uncontrollable urge to go into know-it-all mode I had better be precise at least... :atoz:
 
Last edited:
  • Like
Reactions: ficelles
#87
spwath said:
So then I would want a cab that goes to 40 and below.
Click to expand...

If I crank up the volume with this, I need to wear a jock strap for low B. The driver is not efficient (93db @ 1W/1M IIRC), but that was not a goal for in house use. Ignore the absolute value of db, it's not accurate and doesn't matter. 10-20K pink noise at low volume.

pink-noise-png.png


Actually, if I crank up the bass knob and bass boost on the axe, better wear a cup.
 
#88
HaphAsSard said:
I'm sure @ficelles only meant your "standard bass goes down to like 50hrz" is actually 40.2 Hz (actually 41.2*) - he adds you can calculate harmonics by multiplying the fundamental by integers -, but the suggestion to aim for a strong (at -3 dB or higher) first overtone (AKA second harmonic) still holds: you may or may not want to have your lowest fundamentals (barely) audible (say -10dB), assuming your strings/pickups produce them at any significant level in the first place, but to shoot for having them at or over -3dB would be an extremely difficult task, with no serious pros and countless cons.


*fourty-one point two: if I feel the uncontrollable urge to go into know-it-all mode I had better be precise at least... :atoz:
Click to expand...
I dont see the cons other than a bigger cab?
 
#89
it's not a big deal people he wants deep bass it's ok to expect that. :)

problem is going to big with box volume can offer no further low end and greatly reduce power handling.

going big is ok people don't be afraid and yes the resonant frequency of the driver is in the low 30s so no you dont tune 25hz above
it lol. you tune at fs or 5/7 Hz above or below. that's it

anyways 90 to 115 liters is extremely common for 15s 115 on the larger side. basically 3 cubic feet or 4 if you don't know your conversion.

anyways 112/114 liters 38/40hz
all done
 
Last edited:
  • Like
Reactions: pie_man_25
#90
spwath said:
I dont see the cons other than a bigger cab?
Click to expand...
One situation in which you would benefit from all the bass you can get without needing to boost it from the amp (and reducing headroom) is outdoors with no nearby walls and no PA support; OTOH, indoors too much bass can be problematic - hard-to-predict peaks and nulls resulting from surface reflections, and mud overall - while large stages and PA support, either inside or outside, introduce a whole other set of potential problems: you'd typically either need a large cab or one pointed at you for monitoring purposes, but your bandmates might still need some bass, for clarity, in their floor monitors which would interfere with the lows from your cab, as would the sound coming from the PA subs (sound from the bass cab onstage doesn't magically stop at the edge of the stage), similarly creating peaks and nulls in different listening positions. Sure, you could cut bass when needed, but you can't leave half the cab at home then.

All this ignoring the engineering hurdles, as mentioned by others: big/heavy cab (up to an impractical point), which reduces mechanical power handling (less resistance to fart-out from the air mass), inefficiency so need for more power for the same volume target (assuming you have said power on tap, and assuming the driver can take it; less of a concern in your specific JBL case, but something to take into account in any case).
 
Last edited:
#91
lol and when sunn built the 2000s for noel Redding he had no complaints about his jbl speakers loaded in 114 liters per driver.

likewise acoustic didn't hesitate
with the 406 wide

and neither did ampeg with the svt 215e.

likewise since there all ported around 40Hz just like jbl I'm sure they all have better understanding of very basic reflex boxes designed for.........Bass lol

likewise when looking at your static little graph in winisd. your f3 means nothing people forget about the little shelf eq found on most bass amps called the "bass" knob. it's called eq and depending on the design can offer 12 to 36 db of boost. which you can simulate in winisd. apply 12 to 24dB of boost with a shelf filter and then tell me what your f3 is.
 
Last edited:
#92
BogeyBass said:
it's not a big deal people he wants deep bass it's ok to expect that. :)

problem is going to big with box volume can offer no further low end and greatly reduce power handling.

going big is ok people don't be afraid and yes the resonant frequency of the driver is in the low 30s so no you dont tune 25hz above
it lol. you tune at fs or 5/7 hHz above or below. that's it

anyways 90 to 115 liters is extremely common for 15s 115 on the larger side. basically 3 cubic feet or 4 if you don't know your conversion.

anyways 112/114 liters 38/40hz
all done
Click to expand...
Yeah, jbl recommend 85-285l for that woofer. So I'll probably go 100-150l.
 
#93
BadExample said:
If I crank up the volume with this, I need to wear a jock strap for low B. The driver is not efficient (93db @ 1W/1M IIRC), but that was not a goal for in house use. Ignore the absolute value of db, it's not accurate and doesn't matter. 10-20K pink noise at low volume.

pink-noise-png.png


Actually, if I crank up the bass knob and bass boost on the axe, better wear a cup.
Click to expand...

I would venture to guess that everything below about 40Hz on that plot is inaccurate, full of artifacts and noise.
 
  • Like
Reactions: spankdaplank
#94
agedhorse said:
I would venture to guess that everything below about 40Hz on that plot is inaccurate, full of artifacts and noise.
Click to expand...
I dunno, sir. I did it for fun. Maybe it's where the mic falls out? I did it with an old University Sound dynamic mic, one of 6 I liberated from work. That to a mic preamp to an ART RCA in to USB. Input comes out of USB to ART to effects in. I noticed eq had little effect on 35 Hz down, and figured that was the limitation of the mic. Also couldn't eq 5KHz. Volume was pretty low because pink noise drives me insaner. I do see a hump come up around 30 with a low B with eq flat. I couldn't find anything on the old mics, other than you can buy them used for $5. So I don't know what they have for frequency response. It could be something in the path or the software itself. Who knows. Don't have anyway to test it that I can think of and have no justification to spend money on something calibrated.
 
#95
IME below cab tuning there is a distinct point where vent noise and artefacts begin to overcoat the actual tone.
This point can be easly figured by listening to a gradually dropping sine wave.
Even a calibrated mic doesnt't relate to the SNR (signal to noise ratio) so a published -10dB reponse point tells nothing about sound quality.
With average ported cabs I would not expect a decent "clean" tone around 40Hz still less below.
Any measurement of pure low-response SPL is a different animal cause it does not directly include SNR considerations.
As an example a 40Hz sine wave may produce nothing but artefacts/noise. But as there is no THD demand on the measured signal means that the measured SPL "noise" caused by 40Hz sine "input" can be anything.
(it's kinda confirmation of marketing department goals).
 
Last edited:
  • Like
Reactions: spankdaplank
#96
Rick James said:
They do offer more than one engine choice. :)
Click to expand...

But some times you just have to have a HEMI. Doesnt matter if you really like the F150, you still wont find one with a HEMI on the lot.

Passinwind said:
Not for free.
Yel_wink.gif
Click to expand...

Also, exactly this.

spwath said:
So then I would want a cab that goes to 40 and below.
Click to expand...

The majority of the output from your bass is not in the fundamental frequency. Hitting 40hz for a drop C tuning isnt really advantageous depending on the other priorities in your design. You started out looking to build a cab that was smaller in size.

If that is out the window, then you should just load your drivers in to a true folded horn design.

Titan 48

You will need a cross over, something to pick up the mids and highs, the right power amp to drive it all, and probably some DSP to make it all work, but you would have some pretty decent bass.
 
#97
CL400Peavey said:
But some times you just have to have a HEMI. Doesnt matter if you really like the F150, you still wont find one with a HEMI on the lot.



Also, exactly this.



The majority of the output from your bass is not in the fundamental frequency. Hitting 40hz for a drop C tuning isnt really advantageous depending on the other priorities in your design. You started out looking to build a cab that was smaller in size.

If that is out the window, then you should just load your drivers in to a true folded horn design.

Titan 48

You will need a cross over, something to pick up the mids and highs, the right power amp to drive it all, and probably some DSP to make it all work, but you would have some pretty decent bass.
Click to expand...
I care about weight more. Back loaded horn would be to heavy, and to hard to build
 
#99
Ahhhhh I failed to mention it's a sealed cab. So I may have confused the post. I have alwys thought of snr as an amp spec. I don't think OPs drivers are good candidates for a seald cab so he needs to deal with tuning and possibly an hpf.

ThisBass said:
IME below cab tuning there is a distinct point where vent noise and artefacts begin to overcoat the actual tone.
This point can be easly figured by listening to a gradually dropping sine wave.
Even a calibrated mic doesnt't relate to the SNR (signal to noise ratio) so a published -10dB reponse point tells nothing about sound quality.
With average ported cabs I would not expect a decent "clean" tone around 40Hz still less below.
Any measurement of pure low-response SPL is a different animal cause it does not directly include SNR considerations.
As an example a 40Hz sine wave may produce nothing but artefacts/noise. But as there is no THD demand on the measured signal means that the measured SPL "noise" caused by 40Hz sine "input" can be anything.
(it's kinda confirmation of marketing department goals).
Click to expand...
I
 

Latest posts

Top Bottom
Back