Thank you! I'm going to have to take more time to sit down and plow through all that but certainly appears he put a great deal of money and effort into properly calibrating his system.
I followed your link and what you've posted looks like it will be a 'very interesting' task for you @ least! I (otoh), have been involved and studying "pro-sound audio" for a while ('former' professional live/studio electric bass player) and am just learning car audio since I've had my last two suv's within the last few yrs. It's like what you've said in your post about... "the more projects I complete, the more complex the questions I seem to run into"... That seems to be my experience as we speak, but for me, has always been that way because I enjoy learning so very much; I pity the day when I don't feel that way.
Greg, cheers
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My feelings exactly.. the beginning of wisdom, is, "I do not know"
Getting back to the subject of cabin gain, in the past I've done a number of installs in large 60 - 70s Ford/Mercury/Lincoln sedans. I never saw more than negligible gains related to subwoofer placement in those vehicles. The only exception was in vehicles with a very large trunk: placing the sub immediately behind the wheelwell and firing backwards into the taillights usually results in 3 to 6db gain. As I recall Bazooka more or less pioneered this configuration and as I'm sure we all understand, it is simply an example of corner loading.
The sound deadening materials used in the car's interior will affect sound travel and overall cabin gain to a degree but typically its only the highs and midrange that are absorbed. So placement of the midrange drivers and tweeters is more critical in vehicles with few reflective surfaces and better than average sound deadening.
I have a 2013 F150 crewcab. It has a 5.5ft bed. I'm going to either put a camper top on and connect via rear window removal or make a blow through with a bed cover. There is a considerably different amount of interior volume with these options. I'll be researching all the info thats already been provided and more. Woofers will be Cerwin Vega Stroker 18s.
Thats going to be tricky. I'd probably try to get advice from someone who's actually done a truck bed installation before. You have good taste though, gotta love that Cerwin Vega sound 😀
Hi Wendy'
I've incorporated quite a few C.V. 18" bass-horns over the yrs in some of my larger bass guitar rigs e.g., B-36A, SL-36, and some W-bins w/18" C.V. drivers in the chamber etc... but until now, I wasn't aware that they offered a mobile audio application. I just took a glance @ a few of their drivers (Stroker) and I was pretty impressed; definitely will be looking at them with future car projects in mind! Thx
rigtec, best to you
I have done this before in a 92' extended cab Silverado. I did a blow through with a bed cover on that vehicle (18" Strokers). But like I said earlier it was a 'build it and they will come' approach. I didn't measure cabin gain. I didn't even consider a camper top. I loved it. I guess what I'm trying to do is not leave anything on the table that could be beneficial. Every db of gain below 50hz is a good thing.
I love them. The Strokers I use are no longer in production but can be found used along with recone kits if needed. I credit them with starting the Xmax craze. They still are one of the most unique looking subs out there and are immediately recognized as first gen or 'Old School' Strokers.
Hi NW'
If you do a 'blow through' w/a bed cover, would you still require a box or is this more of a "free air infinite baffle" alignment? I tried to find the t/s parameters for the 18" Stroker but all I could find was the spec sheet; which doesn't include any X-max/mech lim or Qts data, except the fs which was 30hz. Judging by the way it's constructed (spider @both ends of the VC), it stands to have a great deal of excursion capability. Just out of curiosity, do you have a "wish list" regarding your ultimate f3 goal, and how many 18's/watts will you need to achieve it? I'd love to see the write-up!
rigtec, cheers
By 'blow through' I mean that the back wall of the cab and the front wall of the bed will be cut out and connected to allow the subs to play into the cab. There will still be enclosure(s) for the sub(s). I have at my disposal 4 Stroker 18s. They have dual 2 ohm VCs.
Free air resonance 31hz
Total Q 0.191
Mechanical Q 7.923
Electrical Q 0.196
Comp.Vol 5.78 cubic feet
Max Excursion 1.5"
Voice Coil Resistance 1.7 ohms per coil
Vol. Displacement .43 cubic feet
I haven't set any specific goals for the system. I want what everyone wants...the system to play impossibly loud at the lowest frequencies🙂. I want my bass response to undress my passengers😱. It very likely that I'll only use 2 of the Strokers but I do have 4 if I need them. If I had to pick a number/f3 it would be in that 30hz neighborhood. With what I'm reading on cabin gain that shouldn't be hard at all.
I once had the opportunity to crawl... yes CRAWL!! into the chamber of an enclosure built for a pair of 15inch strokers that took up the entire bed of the truck. It was big and ugly, but was rumored to have been VERY loud. From later research I found out it had been designed for the sole purpose of a few small bursts of somewhere between 40 and 60 hertz (long ago, forgot actual tuning point).
That aside, I used to drive a 1989 Jeep YJ, with a single 15, and a pair of cheap 10s just to get it to sound half decent. Needless to say, the location and even ANGLE of the enclosures were ridiculously critical.
That aside, I used to drive a 1989 Jeep YJ, with a single 15, and a pair of cheap 10s just to get it to sound half decent. Needless to say, the location and even ANGLE of the enclosures were ridiculously critical.
Well I don't want a one note system. I do want my cake and I want to eat it too. I want it to reproduce up to the crossover point ~80hz. I've modeled some pretty sweet 6th order enclosures that according to WinISD would play 30-80hz quite loudly. And before I consumed the entire whole bed I'd iso load them and use all 4. The box that I had in my Silverado fit under a Snuglid bedcover and took half of the bed. That was for a pair of DVC 4Ω 18" Strokers....and it was a simple ported enclosure.
😉 I understood what was meant by 'blow through', just wasn't sure how you intended to optimize the drivers; F.A., B.R., or (S).I.B. What you've proposed as a possible goal is definitely do'able for you! With 2 or 4 eighteens on an isobaric baffle, 80 to 30hz should be a "walk in the park"! A lot of people believe they need to hit single digits to seize hearts and pulverise gutz! Truth is, just 50hz will do that when enough (clean) power is utilized. Like in some R&B or rock concerts you may have attended. The bass hits you sooo hard it'll have you 'seeing stars'. But most comm'l subs hover around 45-50hz and need to be configured in a "block" for a nominal (1/3 octave) extension, and the feeling may leave you... speechless! I think my f3 is @ 41hz (based on winISD sim results) but with my "miniDSP" peq/x-over, I have a lot of control over the curve so I can alter it to flatten the room (cabin) with plenty of headroom and gain to spare.
Well said
rigtec (Greg)
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Given that the Strokers don't lend themselves well to sealed enclosures my options are limited to vented or 6th order bandpass. I don't plan on building any type of horn for this application.
I've modeled a 6th order band pass enclosure. The sensitivity of the woofer is 96db 1w:1m. The response of the enclosure is 93db@80hz and 93db@29.5hz. The peaks are centered @ 97.6db@33hz and 97.8db@63hz. There is a dip centered at 93db @ 43.5hz.
My present plan is to employ an Audio Control EQX as the crossover. This unit has a half octave bass eq with bands centered at 31.5hz, 45hz, and 63hz. So I could flatten out the response by cutting ~1.5 db @ 31hz&63hz and boosting ~3db@45hz. This enclosure isn't perfect but definately doable. I'll be tweaking it to try and keep my f3@30hz but eliminate as much of that 40hz dip as I can.
If anybody reading this thread knows of a 'free' site that I can use to host pics please chime in. I tried to use Shutterfly but I can't post to the net from their site.
My present plan is to employ an Audio Control EQX as the crossover. This unit has a half octave bass eq with bands centered at 31.5hz, 45hz, and 63hz. So I could flatten out the response by cutting ~1.5 db @ 31hz&63hz and boosting ~3db@45hz. This enclosure isn't perfect but definately doable. I'll be tweaking it to try and keep my f3@30hz but eliminate as much of that 40hz dip as I can.
If anybody reading this thread knows of a 'free' site that I can use to host pics please chime in. I tried to use Shutterfly but I can't post to the net from their site.
Hi NW,
With regard to a parametric eq. Have you considered a "miniDSP in a box" Advanced 2way stereo xover, see image link:http://www.minidsp.com/images/stories/virtuemart/product/MiniDSP_2x4_RevB_4faa3e0e63676.jpg With it I have 6 bands of "configurable" filters on the L & R input stages; which means that I can set each center band to the frequencies that I need to change (from 10hz to 20,000 on each band), as well as the Q (bandwidth). Each band offers 15db's of gain and cut. The slope of the xover is adjustable e.g., 12db/oct LR, 24, 48 BW, etc and provides you with two channels (L & R), w/two discrete filters on each channel so you could have three different/adjustable xo points. I also have 6 additional (identical) peq filters on the 4 output stages Here's a "screenshot" link to the advanced 21: http://www.minidsp.com/images/stories/virtuemart/product/2_way_Advanced_2_505bd4ba35a0a.jpg
You don't control this eq from the dashboard like you would on a conventional eq. You set the desired parameters on your laptop, from home, or in the truck; in real time. You don't need the internet to adjust your system, you download the firmware to your computer, so it's yours. You connect the laptop (via usb) to the miniDSP in the truck, click the connect button, and make your adjustments. Once you're done and are satisfied w/the system's performance, you hit save, and unplug the usb. You can change the settings of the system as many times as necessary. And here's a PDF data sheet to thumb through if you'd like: http://www.minidsp.com/images/documents/Product Brief- 2way Xover 21 ADV plug-in.pdf I love this program because the hardware is only 2 inch (W) x 4 inch (L) x 1.5 inches (H), and has almost no limit to the EQ's flexability, so you can fix most all the peaks and dips in the sub's response. Let me know what you think,
Greg
AHHH! Sorry NW, I didn't see your last post until just now; guess I was still drafting my previous post when you submitted yours! If you are totally content with the "Audio Control" peq/x-over, then you can just ignore my last contribution; I thought you were seeking a lil extra control over those peaks. But now that I see what you're working with... CARRY ON!
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Here's a look@ my peq/x-over below. The one on the right is a representation of my chosen center freq's, which I've had to work on quite a bit to get it just right; it's not perfect (yet), but definitely very satisfying! On the left is a shot of the whole screen which shows the signal path and operating tools; just to give an idea of it's features.
cheers!
cheers!
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That is a very nice tool right there. If I end up using the modeled enclosure I'm going to have a hard time buying another piece as the bands are pretty much exactly where I need them on the Audio Control piece that I already have. If by chance I choose a different enclosure and could use the flexibility that the miniDSP offers I will certainly consider it. It does seem direct and to the point with no bullship. I like it. Here is the other thing though, my head unit will be an iPad. I'd be willing to bet that someone has put together an app for that.....maybe.
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