Wellll....
After a "few" hours of searching here and other places(and off and on for the past 20 years...yeah long term project). I have come to the conclusion that I might *actually* have a somewhat original idea. Or I am just too foolish to know when to quit... Here is what I have and what I want to accomplish.
Vintage pair of JBL GTi 1500 car audio subs that were based off the 2226 pro audio drivers also from JBL. I have attached the spec and T/S sheet for reference.
What I would ideally like to do is build a relatively simple front loaded single fold on axis horn(coffin style) for each driver. WHY??? Because I have this silly idea of using them not only in my home system, but also in the bed of my truck (with a camper shell and the rear glass removed for a window "blowthrough" with a rubber boot to the cab of the truck, and the enclosures lying on their "backs" with the driver and port facing up).
I am *not* looking to build an SPL system, I just want the best(read flattest) low end extension from these two old subs that I have had forever(but never used...no they are not for sale, sorry). In fact the enclosures will only be in the truck for special events...most of the time they will be inside being run off a Crown PSA-2. I would be happy to get a band pass from say 30-100Hz, I know I am pushing both the upper and lower limits there, Fs is 35Hz and the Xmax is only 5.46mm.
Obviously enclosure placement and tuning will be all different between the two uses. In the truck as mentioned they will be side by side firing up into the fiberglass campershell area. Creating a rear horn loaded 4th order???maybe?? The campershell space being the front chamber and the window boot being a port of sorts...at least that is how I see it in my mind.
In the home system they will be corner loaded in a smaller room, with ever changing main speakers and most likely a lower upper band pass frequency...say 60hz or so.
Regardless, I am prepared to make some sacrifices to use what I already have.
I tentatively played around with HornResp, but I feel like I am missing a bit too much to invest too much time, so here I ask for help, advice, constructive criticism.
My only real space restrictions(in the upright "inside" home position) are the front width(total of 40 inches for both, 20 for each enclosure) and the depth at ideally 16 inches. The "front" will have both the driver and the port. The height can be adjusted for proper port length(I came up with 96.85 inches total) which I have guessed to be somewhere between 48 and 56 inches but up to 72 inches if need be...please dont shoot me for not using metric...I still have 1728cu.in branded into my old brain, just wont go away...smdh.
Straight, flared, tapped, conical....all have been before my eyes. Confusion is setting in strong... Too many variables from inexperience. I have built plenty of different kinds of enclosures over the years, but none this complicated or intended for dual use, if that is even possible.
I reread this twice. Not sure if continuing to edit it will make it even more confusing... Thanks for at least reading this far, even if you are shaking your head.... 🙄
After a "few" hours of searching here and other places(and off and on for the past 20 years...yeah long term project). I have come to the conclusion that I might *actually* have a somewhat original idea. Or I am just too foolish to know when to quit... Here is what I have and what I want to accomplish.
Vintage pair of JBL GTi 1500 car audio subs that were based off the 2226 pro audio drivers also from JBL. I have attached the spec and T/S sheet for reference.
What I would ideally like to do is build a relatively simple front loaded single fold on axis horn(coffin style) for each driver. WHY??? Because I have this silly idea of using them not only in my home system, but also in the bed of my truck (with a camper shell and the rear glass removed for a window "blowthrough" with a rubber boot to the cab of the truck, and the enclosures lying on their "backs" with the driver and port facing up).
I am *not* looking to build an SPL system, I just want the best(read flattest) low end extension from these two old subs that I have had forever(but never used...no they are not for sale, sorry). In fact the enclosures will only be in the truck for special events...most of the time they will be inside being run off a Crown PSA-2. I would be happy to get a band pass from say 30-100Hz, I know I am pushing both the upper and lower limits there, Fs is 35Hz and the Xmax is only 5.46mm.
Obviously enclosure placement and tuning will be all different between the two uses. In the truck as mentioned they will be side by side firing up into the fiberglass campershell area. Creating a rear horn loaded 4th order???maybe?? The campershell space being the front chamber and the window boot being a port of sorts...at least that is how I see it in my mind.
In the home system they will be corner loaded in a smaller room, with ever changing main speakers and most likely a lower upper band pass frequency...say 60hz or so.
Regardless, I am prepared to make some sacrifices to use what I already have.
I tentatively played around with HornResp, but I feel like I am missing a bit too much to invest too much time, so here I ask for help, advice, constructive criticism.
My only real space restrictions(in the upright "inside" home position) are the front width(total of 40 inches for both, 20 for each enclosure) and the depth at ideally 16 inches. The "front" will have both the driver and the port. The height can be adjusted for proper port length(I came up with 96.85 inches total) which I have guessed to be somewhere between 48 and 56 inches but up to 72 inches if need be...please dont shoot me for not using metric...I still have 1728cu.in branded into my old brain, just wont go away...smdh.
Straight, flared, tapped, conical....all have been before my eyes. Confusion is setting in strong... Too many variables from inexperience. I have built plenty of different kinds of enclosures over the years, but none this complicated or intended for dual use, if that is even possible.
I reread this twice. Not sure if continuing to edit it will make it even more confusing... Thanks for at least reading this far, even if you are shaking your head.... 🙄
Attachments
I had looked at that before, but that is for a more traditional car audio sub. The drivers I have, have the same basket/motor(for the most part) as the JBL pro audio 2226 with an accordion cloth surround, but with a heavier cone and 4 ohm nominal impedance.
Most of the T/S parameters that seem to matter from what I have gleaned from several different threads seem to point to this being a decent driver for a basic folded horn: Honestly I was hoping someone might see something in them that I may be missing and point me in the right direction. I have found a few different calculators, but none have worked so far.
you might ask Weltersys if the Keystone is in that size range. With a small mouth, I'm not sure how low you'd want to go
rough example 2M and 2.5M long
rough example 2M and 2.5M long
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you might ask Weltersys if the Keystone is in that size range. With a small mouth, I'm not sure how low you'd want to go
rough example 2M and 2.5M long
Thank You so very much!! I was just reading about keystone restricter plates, seems like a good thing to be able to switch out, especially with my wacky idea of using both for mobile and home audio. I would like to go as low as possible but really do not want to damage the driver, big reason it wont spend much time in the auto environment either. I actually have two of the Crown amps, so I will have to be careful with the volume for sure. By no means will these be the final sub solution for my main home setup, but for now...it will be nice to use these after all these years.
Your graphs are alot different that what I was getting, so I am not sure what was going on. Most likely user error on my part, but I knew things werent looking right.
I also realized I was using a very, very old version of HornResp, so I got that updated after reading about some of the compatibility issues. Still user error though probably....smh.
I will definitely give this all another good go in the morning when I am a bit more awake and refreshed. Thanks again for the help! 🙂
you should be able to beat my rough try - maybe Brian Steele has a sheet to help pack that into the form you want (?)
poking such a horn in a good solid corner would help flatten its response
poking such a horn in a good solid corner would help flatten its response
Couldn't sleep, go figure. Must of been that diaphragm displacement of the 2.5M you showed me. Thats the calculated excursion (Xmax)? Gets a bit out of spec below the highlighted 46.86Hz.... Oh well, still might be a fun build. There is plenty of stuff I listen to that doesnt get anywhere near that low. Mostly acoustic stuff. The teenager inside me still wants(and will someday get) that flat to 20, no questions asked. Either you can feel it or you cant.
Yes I was looking at Brian Steele's Excel books earlier, struggling with a few(locked inputs?), but I think I can figure it out....eventually. Just needed a nudge in the right direction. And to know that the driver was at least fairly suited to these types of enclosures, pretty sure I will build at least one now. Two if I am lucky... 🙂
If you've got a USB soundcard and a couple of adapters, it's worth double-checking the T/S parameters before committing to a build.
As a sanity-check, what does a ported box give you?
Chris
As a sanity-check, what does a ported box give you?
Chris
Yeah... I have a couple different usb sound card options, plus a really old handheld RTA. I have some performance mics, but nothing calibrated. Havent pulled T/S parameters manually in decades, but you are right, every speaker has it's own values. Especially the compliance and "break in" effects, at least so I have learned.
As for the sanity check...well, more of a skills check...smh...
I would love to blame lack of time, but I gave modeling a vented closure a "quick" try and didnt have much luck with HornResp. It has been years since I used the older version, and yeah...I hate excuses...Time to reread the tutorials and what not available.
Thank You all regardless...I dont give up easy and didnt want to ghost this thread.
here's an 85 liter 42Hz sim in hornresp at 2V drive
Thanks for the hint.. 🙂 I do believe I am overthinking the software a bit. I do tend to jump into the deep end first though. Time to swim I guess...
When I 'run the numbers' I get a 500 L net compression horn, which converted to parabolic, while smaller, looks horrible, or ~450 L net TH, leaving TTQWT the only viable horn @ ~148 L net to compare to the reflex.
GM
GM
sorry on the expansion. This cabinet fits those constraints - maybe eyeball its hornresp input - if looks good - buy the plan.
https://i.imgur.com/0sLjk.jpg
https://i.imgur.com/0sLjk.jpg
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GM - does this sim of the above horn image look correct as far as flare goes? My health is shot and it takes a lot of explaining as to how to do things. I think the baffle opening would be a 13.3" hole.
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No biggie, but since you didn't export your file I didn't vet it and only knew that the hyperbolic I did outperformed yours till I converted it to parabolic, so just wanted to compare 'apples to apples'.
My eyes probably aren't much, if any, better than yours nowadays, so without the plans I really don't know if for no other reason than have never had the need to do complex folding to make a horn fit a specific 3D space. That third 'D' can really be a PITA, so the few I needed done I had someone with [early] CAD skills do it and with no simming capability can only say they measured good enough to meet the needs of the app.
Regardless, if its build complexity poses no problems for the OP, then on paper it looks to be the best performer overall; otherwise my simple one fold TTQWT.
GM
??? Sd = 877 cm/S2 = 175 cm = 5.011:1 CR! Combined with what appears to be a relatively tiny low pass [front] chamber [S1-S2] preloading it, it won't take many watts to 'choke' the driver down low, so if this is per the above 'plan', then TTBOMK not a good one.
GM
I don't know of a service to store the text files - FWIW - here it is pasted, Your pipe reaches real low. The horn does more in its midbass area but looks pretty complex to build. Is the flare usually parabolic for a constant width expansion within two parallel walls? (I see conic descriptions often for segments)
ID=48.20
Ang=0.5 x Pi
Eg=2.00
Rg=0.00
Fta=7.17
S1=50.00
S2=175.00
Par=22.00
F12=0.00
S2=175.00
S3=1155.00
Par=270.00
F23=0.00
S3=1155.00
S4=2376.00
Par=56.20
F34=0.00
S4=0.00
S5=0.00
L45=0.00
F45=0.00
Sd=877.00
Bl=13.49
Cms=1.73E-04
Rms=4.53
Mmd=104.59
Le=0.98
Re=2.50
OD=1
Vrc=55.00
Lrc=15.00
Fr=0.00
Tal=0.00
Vtc=0.00
Atc=0.00
Pmax=100
Xmax=5.5
Path=0.0
Mass=0.00
Re'=0.00
Leb=0.00
Le=0.00
Ke=0.00
Rss=0.00
Rms=0.00
Ams=0.00E+00
Fr1=0.00
Fr2=0.00
Fr3=0.00
Fr4=0.00
Tal1=100
Tal2=100
Tal3=100
Tal4=100
Comment=Horn Guess
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
FILTER
0 0.01 0.0 -1 0 0.01 0.0 -1 0 0.01 0.0 -1
0 0.01 0.0 -1 0 0.01 0.0 -1 0 0.01 0.0 -1
100 25 0 0
40.50.50.5
0.50.50.50.5
SSSS
0111
1011
0022
1111
111
000
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ID=48.20
Ang=0.5 x Pi
Eg=2.00
Rg=0.00
Fta=7.17
S1=50.00
S2=175.00
Par=22.00
F12=0.00
S2=175.00
S3=1155.00
Par=270.00
F23=0.00
S3=1155.00
S4=2376.00
Par=56.20
F34=0.00
S4=0.00
S5=0.00
L45=0.00
F45=0.00
Sd=877.00
Bl=13.49
Cms=1.73E-04
Rms=4.53
Mmd=104.59
Le=0.98
Re=2.50
OD=1
Vrc=55.00
Lrc=15.00
Fr=0.00
Tal=0.00
Vtc=0.00
Atc=0.00
Pmax=100
Xmax=5.5
Path=0.0
Mass=0.00
Re'=0.00
Leb=0.00
Le=0.00
Ke=0.00
Rss=0.00
Rms=0.00
Ams=0.00E+00
Fr1=0.00
Fr2=0.00
Fr3=0.00
Fr4=0.00
Tal1=100
Tal2=100
Tal3=100
Tal4=100
Comment=Horn Guess
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
FILTER
0 0.01 0.0 -1 0 0.01 0.0 -1 0 0.01 0.0 -1
0 0.01 0.0 -1 0 0.01 0.0 -1 0 0.01 0.0 -1
100 25 0 0
40.50.50.5
0.50.50.50.5
SSSS
0111
1011
0022
1111
111
000
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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