I used your LAB16 specs in those sims. Here's what the low tuning from that 46cm long vent does with the larger volume:
Yes.....that’s just about what my free ‘speaker box’ app came up with.
So if I cross at 80hz or so (12db) should be decent no?
I can high pass the bottom if it’s gonna get into over excursion.
What do you think?
I really appreciate all the help btw
Bob
So if I cross at 80hz or so (12db) should be decent no?
I can high pass the bottom if it’s gonna get into over excursion.
What do you think?
I really appreciate all the help btw
Bob
David McBean's hornresp is free and am sure positive used by some of the pros.
you would probably be better off with a bass reflex - or maybe a tapped pipe as the little "horn" is just providing a nasty peak.
look what a tiny bandpass box might do:
xmax would not be hit it its passband with 1.6KW - it would just burn up.
Ask some of the guys who work with PA equipment what they would build withi your woofers.
Here's a good ol' bass reflex
you would probably be better off with a bass reflex - or maybe a tapped pipe as the little "horn" is just providing a nasty peak.
look what a tiny bandpass box might do:
xmax would not be hit it its passband with 1.6KW - it would just burn up.
Ask some of the guys who work with PA equipment what they would build withi your woofers.
Here's a good ol' bass reflex
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I need to get a windows based setup just for this kind of thing....as of now I’m limited to apps with a chrome book and a iPad.
Looks fairly flat down to 30hz which is as much as I’m gonna need and I’ve got dsp hp/lp on the amp (xls 2002) along with analog hp/lp on the reciever available also so straightening out the hump shouldn’t be too difficult.....should also push the upper resonance down -25db.
You wouldn’t build it?
Thanks again freddi
Looks fairly flat down to 30hz which is as much as I’m gonna need and I’ve got dsp hp/lp on the amp (xls 2002) along with analog hp/lp on the reciever available also so straightening out the hump shouldn’t be too difficult.....should also push the upper resonance down -25db.
You wouldn’t build it?
Thanks again freddi
that reflex looks good to me at around 100 liters internal volume - its not going to be too big/heavy - plus can hit almost any low frequency bass-drop in modern "music" It might need more vent area if hit with a kilowatt around 29Hz - but that's not likely.
Ok cool.....guess I got some reconsidering to do.
Size (just has to be shorter than 27”)or weight isn’t an issue as it’s going to be a semi permanent bottom for my main home system.
Might just test build the C15 just to see what it sounds like....then if need be go back to basic reflex.
Thanks man!
Bob
Size (just has to be shorter than 27”)or weight isn’t an issue as it’s going to be a semi permanent bottom for my main home system.
Might just test build the C15 just to see what it sounds like....then if need be go back to basic reflex.
Thanks man!
Bob
for space saving, that LAB15 woofer would work OK in a 1 cubic foot sealed box with 600uF series capacitor as long as the amp has low source impedance and the cap pretty good in quality (I have an xls2000 - great little amp)
Freddi I know you’ve got to better things to do, but my speaker box app doesn’t calculate the upper register like yours does....just goes flat on up.
If you can could you try everything else the same but 10” more port length?
Is there any issues with folded ports? I suppose that also reduces box volume?
Thanks.....I won’t bug you anymore after this!
If you can could you try everything else the same but 10” more port length?
Is there any issues with folded ports? I suppose that also reduces box volume?
Thanks.....I won’t bug you anymore after this!
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the deeper its tune, the worse things will get - the lower portion of response will probably be around 88-90dB and the long vent will have its own harmonics besides taking up more space. I have a 4th order bandpass box with similar vent and its got some bad spikes.
Just damp it !
(waterfall/wavelet are done from hornresp impulse sim unstuffed into REW)
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...dhhhoooo...cannot re-edit/delete last post. It only apply for low power ~<115db max 2pi that don't need that much big port (100cm²).
the way it was drawn: for home use I'd think it be better to make a simple bass reflex
C-15 with his LAB15 variant
C-15 with his LAB15 variant
Well looks like I might be beatin a dead horse with this one.....might just try them sealed @ 3cf (critically damped f3 58hz / f10 28hz) first and see what kinda room gain I get.
Thanks Freddi
And not quite sure what your working at papasteack ?
Thanks Freddi
And not quite sure what your working at papasteack ?
bass reflex - you could pick one like 6th order - I think that alignment is considered to be critically damped for a reflex
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Thanks (0) Thanks(0) Quote _djk_ Quote Post ReplyReply Direct Link To This Post Posted: 01 August 2010 at 1:09am
The classic B6 assisted alignment is best with a Qts=0.312
This requires a high=pass filter of a Q=2 at Fb, and the Fb=Fs.
Because the moderate boost is at Fb, cone excursion doesn't go up a lot, and distortion is low.
The quick calculator fudge (Qts=0.312) is Vas*0.4 = box size.
For different Qts values, use (Qts^2)*Vas*4.5 = box size. Fb should be (Fs/Qts)*0.312
Trick:
If the Qts is a bit low, just pretend it is a bit higher (no more than 20% or so). This works because you are pretending the motor is weaker than it actually is (obviously doesn't work the other way if the Qts is too high). Also, when driving hard the Bl goes down and the cabinet is now correctly tuned!
The quick B4 calculator fudge (Qts=0.4) is Vas*0.8 = box size, Fb=Fs.
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0.*3.4Joined: 23 November 2004
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Thanks (0) Thanks(0) Quote _djk_ Quote Post ReplyReply Direct Link To This Post Posted: 01 August 2010 at 1:09am
The classic B6 assisted alignment is best with a Qts=0.312
This requires a high=pass filter of a Q=2 at Fb, and the Fb=Fs.
Because the moderate boost is at Fb, cone excursion doesn't go up a lot, and distortion is low.
The quick calculator fudge (Qts=0.312) is Vas*0.4 = box size.
For different Qts values, use (Qts^2)*Vas*4.5 = box size. Fb should be (Fs/Qts)*0.312
Trick:
If the Qts is a bit low, just pretend it is a bit higher (no more than 20% or so). This works because you are pretending the motor is weaker than it actually is (obviously doesn't work the other way if the Qts is too high). Also, when driving hard the Bl goes down and the cabinet is now correctly tuned!
The quick B4 calculator fudge (Qts=0.4) is Vas*0.8 = box size, Fb=Fs.
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Here you go - 69 liter bass reflex tuned to 22.8Hz. This would be good IF you can get a good vent in there - maybe right angle - or top to bottom exiting at the floor with box elevated a bit ??
also 6dB of Q=2 peaked 2nd order highpass filter would make it ~ flat to 22Hz
its tuned about a Hz high in the sim as the 76sq.cm. vent was a half meter long at that point
And here's that 69 liter box with EQ
also 6dB of Q=2 peaked 2nd order highpass filter would make it ~ flat to 22Hz
its tuned about a Hz high in the sim as the 76sq.cm. vent was a half meter long at that point
And here's that 69 liter box with EQ
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Here you go - 69 liter bass reflex tuned to 22.8Hz. This would be good IF you can get a good vent in there - maybe right angle - or top to bottom exiting at the floor with box elevated a bit ??
also 6dB of Q=2 peaked 2nd order highpass filter would make it ~ flat to 22Hz
its tuned about a Hz high in the sim as the 76sq.cm. vent was a half meter long at that point
[/QUOTE
I used your figure of 3CF for that comparison. The 69 liter ~23Hz tuned vented box is attractive to me without EQ - look at that post to see what EQ does for it. Those formulas (assume Don Keele Jr.) work.
here it is again -seems like a little assisted - boosted 6th order vented box like so would be best with maybe an 18" passive radiator
you can see I set the EQ for 5dB peaking at 22Hz rather than 6 - and it pumps up the input power - in that one rather
narrow region. In the days of turntables, that underdamped 2nd order highpass filter was great as got rid of a lot of useless
cone excursion below the useful range of the speaker.
here it is again -seems like a little assisted - boosted 6th order vented box like so would be best with maybe an 18" passive radiator
you can see I set the EQ for 5dB peaking at 22Hz rather than 6 - and it pumps up the input power - in that one rather
narrow region. In the days of turntables, that underdamped 2nd order highpass filter was great as got rid of a lot of useless
cone excursion below the useful range of the speaker.
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the way it was drawn: for home use I'd think it be better to make a simple bass reflex
C-15 with his LAB15 variant
What I had in mind in the first place was this configuration and if I set the lp on the xls2002 at 80hz (12db) would that not bring the hump down to where I could meet it with the hp on the reciever (160 on down)
Or is that just not gonna work like I think it is?
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