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LOL. I am not sure if anything that ridiculous will occur, but I could look into a Dual SAN 21" box that is a 16Hz tuned monster. Something sort of like a SKHorn or MAUL...
yes!! :D
 

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Discussion Starter #22
. Does anyone have measured specs from one of these JBL drivers? Ideally you want the semi inductance parameters included too. Those make a big difference. Not trying to be a downer here but it is what it is.

Found it! Matt measured one years ago. No semi inductance though.
Chris

I grabbed a pair of these just to check out, I thought I would share the T/S specs I measured on one after some break in:

* This data was exported from DATS the Dayton Audio Test System
* Manufacturer: JBL
* Model: CS1214
* Piston Diameter = 260.4 mm
* f(s)= 25.57 Hz
* R(e)= 3.439 Ohms
* Z(max)= 40.8 Ohms
* Q(ms)= 6.488
* Q(es)= 0.5972
* Q(ts)= 0.5468
* V(as)= 104.6 liters (3.694 cubic feet)
* L(e)= 3.16 mH
* n(0)= 0.2792 %
* SPL= 86.56 1W/1m (90.72dB 2.83v/1m)
* M(ms)= 147.4 grams
* C(ms)= 0.263 mm/N
* BL= 11.68

A few other thoughts, I would not use these past about 15mm as the spider really locks up beyond that point and audible distortion ramps up quite a bit when trying to push them further. But they are nice and quiet up to rated xmax. The 1260w/1262w followed a similar pattern. Likely designed with durability in mind to prevent over excursion and bottoming.
 

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WOW, you made the thread already, holy moly this project moves fast, LOL!

Again, awsome job on the enclosure, and the build thread, thank you so much for doing this :)

Not so great news from Ricci, but we will see when you fire it up, how it behaves. Can’t wait ;)
 

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Thanks...

I think the Dats includes the semi inductance specs in the full data file? Maybe he still has it? Seems like a popular driver itd be good to have it for the modeling
 

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Discussion Starter #27
Thanks...



I think the Dats includes the semi inductance specs in the full data file? Maybe he still has it? Seems like a popular driver itd be good to have it for the modeling
@mtg90
Matt, any chance you still have that info?

Thanks,
Chris
 

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@a77cj7

I've really enjoying this thread - I can't wait to hear your thoughts on how they work out. I would like to ask you a few build-related questions:

1. What kind of Kreg are you using?
2. What size/type screws are you using for the Kreg pockets?
3. How do you like the Kreg? I've never used one.

Thanks for the exciting work so far!

Dave
 

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Would be Wright parameters be what is needed? I forgot to include those previously.

* This data was exported from DATS the Dayton Audio Test System
*
* Manufacturer: JBL
* Model: CS1214
* Piston Diameter = 260.4 mm
* f(s)= 25.57 Hz
* R(e)= 3.439 Ohms
* Z(max)= 40.8 Ohms
* Q(ms)= 6.488
* Q(es)= 0.5972
* Q(ts)= 0.5468
* V(as)= 104.6 liters (3.694 cubic feet)
* L(e)= 3.16 mH
* n(0)= 0.2792 %
* SPL= 86.56 1W/1m
* M(ms)= 147.4 grams
* C(ms)= 0.263 mm/N
* BL= 11.68
* K(r)= 0.02195
* X(r)= 0.697
* K(i)= 0.0405
* X(i)= 0.6984
 

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in the spirit of community "interest"

@dasa2131

kregs in either 1/2 or 3/4 ply,
probably not in MDF
totally a way to go for the enthusiastic wood bender

1 issue for me and others more likely when using PL3 at the same time
as mentioned above-
kreg "kreep", usually in the range of a fat 1/16th
but annoying as H3LL
and for DIY audio, not likely to be a huge issue for the box,
it would be the room /placement and all of "THAT" that's creating optimum challenge

re-enforces the notion of dry mock up and the use of stabilizers, stop blocks, clamps, whatever it takes. .

Back to the original program . . .

Can't wait for it to be fired up . ..
 

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What does the excursion of this design look like in the 20-30hz range?

The response of this design looks very similar to the Quad GRS 10" 6th order series tuned bandpass sub I built a little while back. One of the main issues with that design was that the peak in the response (~105-110hz on mine) caused an amplification of the driver 3rd and 4th order harmonics in the 25-35hz range which just happened to coincide with the excursion maximum where such distortion was most prevalent.

The JBL's are likely cleaner but I'd watch for the same kind of rise in distortion in the 20-30hz range.

Edit: looked at my measurements again and it was just the 3rd order harmonics that got boosted.
 

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Discussion Starter #32
@a77cj7



I've really enjoying this thread - I can't wait to hear your thoughts on how they work out. I would like to ask you a few build-related questions:



1. What kind of Kreg are you using?

2. What size/type screws are you using for the Kreg pockets?

3. How do you like the Kreg? I've never used one.



Thanks for the exciting work so far!



Dave


1. K4 jig.
2. 1” coarse thread. Should have gone 1 1/4”, but was worried about poking through the 18mm ply. To compensate, I’m running 5/8 setting on the block, but 3/4 drill depth. Not ideal.
3. Besides the kreep, absolutely love it. Easy, fast, effective. The kreep can be minimized and mitigated with proper clamping or other methods as mentioned above.

Chris
 

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Discussion Starter #33 (Edited)
Would be Wright parameters be what is needed? I forgot to include those previously.



* This data was exported from DATS the Dayton Audio Test System

*

* Manufacturer: JBL

* Model: CS1214

* Piston Diameter = 260.4 mm

* f(s)= 25.57 Hz

* R(e)= 3.439 Ohms

* Z(max)= 40.8 Ohms

* Q(ms)= 6.488

* Q(es)= 0.5972

* Q(ts)= 0.5468

* V(as)= 104.6 liters (3.694 cubic feet)

* L(e)= 3.16 mH

* n(0)= 0.2792 %

* SPL= 86.56 1W/1m

* M(ms)= 147.4 grams

* C(ms)= 0.263 mm/N

* BL= 11.68

* K(r)= 0.02195

* X(r)= 0.697

* K(i)= 0.0405

* X(i)= 0.6984

Thanks Matt! I’m impressed you still have the data.

Not in any form I recognize. I’ve used semi inductance for modeling, but am not familiar with the calculations behind it.
@Ricci?

Chris
 

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Discussion Starter #34
What does the excursion of this design look like in the 20-30hz range?



The response of this design looks very similar to the Quad GRS 10" 6th order series tuned bandpass sub I built a little while back. One of the main issues with that design was that the peak in the response (~105-110hz on mine) caused an amplification of the driver 3rd and 4th order harmonics in the 25-35hz range which just happened to coincide with the excursion maximum where such distortion was most prevalent.



The JBL's are likely cleaner but I'd watch for the same kind of rise in distortion in the 20-30hz range.


Not sure on HR’s displacement modeling on this one, as mentioned. But, on 1000w input:


Chris
 

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Discussion Starter #35
Minor updates tonight. Enclosures are now complete and awaiting drivers to arrive. Should have them on Friday.

Chris
 

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Would be Wright parameters be what is needed? I forgot to include those previously.

* This data was exported from DATS the Dayton Audio Test System
*
* Manufacturer: JBL
* Model: CS1214
* Piston Diameter = 260.4 mm
* f(s)= 25.57 Hz
* R(e)= 3.439 Ohms
* Z(max)= 40.8 Ohms
* Q(ms)= 6.488
* Q(es)= 0.5972
* Q(ts)= 0.5468
* V(as)= 104.6 liters (3.694 cubic feet)
* L(e)= 3.16 mH
* n(0)= 0.2792 %
* SPL= 86.56 1W/1m
* M(ms)= 147.4 grams
* C(ms)= 0.263 mm/N
* BL= 11.68
* K(r)= 0.02195
* X(r)= 0.697
* K(i)= 0.0405
* X(i)= 0.6984


Crap...Wright model won't work. Do you still have the measurements saved? If you do can you export the free-air impedance curve and the added mass curve as text or zma files. We can get them from that information with Bolserst's calculator spreadsheet.


Edit: Need the amount of mass used too!
 

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What does the excursion of this design look like in the 20-30hz range?

The response of this design looks very similar to the Quad GRS 10" 6th order series tuned bandpass sub I built a little while back. One of the main issues with that design was that the peak in the response (~105-110hz on mine) caused an amplification of the driver 3rd and 4th order harmonics in the 25-35hz range which just happened to coincide with the excursion maximum where such distortion was most prevalent.

The JBL's are likely cleaner but I'd watch for the same kind of rise in distortion in the 20-30hz range.

Edit: looked at my measurements again and it was just the 3rd order harmonics that got boosted.
Excellent point made here that bears repeating. This is why I generally try to avoid large peaks in the response as much as possible or at least try to push them out of band as much as possible. 100Hz peak boosts the 3rd harmonic of 33Hz, 4th of 25Hz etc, where excursion and distortion is usually getting large. A 200Hz peak on the other hand is the 3rd harmonic of 67Hz and the 4th of 50Hz. Excursion and distortion is usually lower at higher frequencies. With subs the 3rd harmonic is usually the one I watch for the most followed by the 2nd and 4th at a little lower priority.
 

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Discussion Starter #38
Crap...Wright model won't work. Do you still have the measurements saved? If you do can you export the free-air impedance curve and the added mass curve as text or zma files. We can get them from that information with Bolserst's calculator spreadsheet.


Edit: Need the amount of mass used too!

@Ricci

Chris @Chris Popovich took these measurements. Top is un-broken in driver, bottom is broken in with added dust cap.



Significant difference from @mtg90’s.

Chris P is going to try and find a broken-in driver and take a new measurement.

Chris
 

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Discussion Starter #39
Excellent point made here that bears repeating. This is why I generally try to avoid large peaks in the response as much as possible or at least try to push them out of band as much as possible. 100Hz peak boosts the 3rd harmonic of 33Hz, 4th of 25Hz etc, where excursion and distortion is usually getting large. A 200Hz peak on the other hand is the 3rd harmonic of 67Hz and the 4th of 50Hz. Excursion and distortion is usually lower at higher frequencies. With subs the 3rd harmonic is usually the one I watch for the most followed by the 2nd and 4th at a little lower priority.


Sorry for being a complete noob here, but...

How does the 3rd harmonic distortion present? Is it an artifact of the driver’s distortion at the peak frequency, or is it dependent on the distortion at the 3rd harmonic? Does reducing the peak via eq reduce this effect, or is it inherent to the acoustic properties of the box?

I currently run Mini Devastators loaded with 18ds115’s in my theater. They have a huge peak in response. Model vs close-mic:

Subjectively, these are the cleanest subwoofers I’ve heard. Of course, the 18ds115 is a very low-distortion driver. And I am running with the peak significantly eq’d down.

Chris
 
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