For a while now I've had a VW T4 Caravelle (known as a 'Eurovan' to the yanks out there I believe)
The standard audio system it came with was actually not too bad but I've been tinkering with just about everything on the van including the sound quality.
I'm now running:
Nexus7 - CM11 - Poweramp (generally .flac)
¦
Bluetooth conection
¦
JVC KD-X50BT
¦ ¦
¦ Tweeters under windshield + 6.5"s in the doors on front channel
4" full rangers (HA!) in the rear headlining on rear channel.
(Hope that makes sense)
There was a rather large 'cabin mode' at 130hz but I've notched it out with Poweramp's EQ.
Constraints-
1st: This is the Caravelle so it has seats everywhere, I have four kids, and I use the van four work quite a bit (Tools, timber, random cr@p) So I don't have a lot of options of where to put a sub. The best option for me seems to be under the front console, in front of the gearstick. As HERE
That limits the volume to play with to around 22L (3/4 of a cubic ft)
2nd: I already have the driver from many years ago (bought to go in my first car, which, erm, crashed itself
)
It is a Kenood KFC-W2509:
RMS (Watts) 350
Vas (liters) 44.04
Fs (Hz) 35
Qts 0.42
Xmax (millimeters) 8
At the moment I can't justify buying another sub just to fill in the bottom end of the van stereo so this is what I'm using, along with a 260Wrms amp.
Now I'm no bass-head but I do enjoy 'ALL' types of music, including some which extend below 40Hz. I don't want to be competing with the Suped-up nova chavs in terms of volume but I'd like to be able to hear the music well over the engine/road noise which I'm thinking is maybe 75dB. Reducing cabin noise is in the pipeline too but down the line a little.
Digging out and dusting off my Hornresp and playing with CAD I came up with this:
Which I think I can make work with a little EQ-ing, but it worries me that the mouth is so small. I may be able to improve the aspect ratio (currently about 300 x 13 mm) but its still only 25mm2. am I really going to get much bass out of it?
And today I came across the transfer function concept which leads me to think that maybe I should be aiming for a response which drops around 12db between 60 and 30Hz. Or should I just EQ the cabin gain out and benefit from the reduced displacement?
As I say- I've put a lot of hours into this so far and now I'm feeling like I'm back to square one.
Any pointers from those more knowledgeable in these things would be much appreciated
The standard audio system it came with was actually not too bad but I've been tinkering with just about everything on the van including the sound quality.
I'm now running:
Nexus7 - CM11 - Poweramp (generally .flac)
¦
Bluetooth conection
¦
JVC KD-X50BT
¦ ¦
¦ Tweeters under windshield + 6.5"s in the doors on front channel
4" full rangers (HA!) in the rear headlining on rear channel.
(Hope that makes sense)
There was a rather large 'cabin mode' at 130hz but I've notched it out with Poweramp's EQ.
Constraints-
1st: This is the Caravelle so it has seats everywhere, I have four kids, and I use the van four work quite a bit (Tools, timber, random cr@p) So I don't have a lot of options of where to put a sub. The best option for me seems to be under the front console, in front of the gearstick. As HERE
That limits the volume to play with to around 22L (3/4 of a cubic ft)
2nd: I already have the driver from many years ago (bought to go in my first car, which, erm, crashed itself
)It is a Kenood KFC-W2509:
RMS (Watts) 350
Vas (liters) 44.04
Fs (Hz) 35
Qts 0.42
Xmax (millimeters) 8
At the moment I can't justify buying another sub just to fill in the bottom end of the van stereo so this is what I'm using, along with a 260Wrms amp.
Now I'm no bass-head but I do enjoy 'ALL' types of music, including some which extend below 40Hz. I don't want to be competing with the Suped-up nova chavs in terms of volume but I'd like to be able to hear the music well over the engine/road noise which I'm thinking is maybe 75dB. Reducing cabin noise is in the pipeline too but down the line a little.
Digging out and dusting off my Hornresp and playing with CAD I came up with this:
Which I think I can make work with a little EQ-ing, but it worries me that the mouth is so small. I may be able to improve the aspect ratio (currently about 300 x 13 mm) but its still only 25mm2. am I really going to get much bass out of it?
And today I came across the transfer function concept which leads me to think that maybe I should be aiming for a response which drops around 12db between 60 and 30Hz. Or should I just EQ the cabin gain out and benefit from the reduced displacement?
As I say- I've put a lot of hours into this so far and now I'm feeling like I'm back to square one.
Any pointers from those more knowledgeable in these things would be much appreciated
Functionally, your design looks more like a bass reflex than a TH. The exit port does appear to be quite small, it will probably chuff and have non-linear output, that is, not get as loud as predicted at the excursion predicted.
I'd suggest modeling a simple BR cabinet to see if the TH offers any more level in that small enclosure size. Also (not that it will make much difference in the response) use Par (abolic) to model TH using flat pieces of plywood with two parallel sides.
Although cabin gain will reinforce LF more than upper frequencies, better to have it and cut it than not have it and attempt to boost it. That said, no reason that the response has to be flat, an upward tilt is OK.
Hi, thanks for the response.
I have already done as you suggest actually and come up with this:
A decent looking response from a vented cab, IF the cabin gain kicks in as expected around 50Hz. looking at the Infinity plots for their recommended boxes the in car response seems to do just that -but about 60-70hz. However I've been using room mode calculators with the internal dimensions of my van (which is obviously rather larger than most cars) And the longest dimension (front to back) seems to produce a mode at 49Hz. Would I be right in thinking that is where the transfer function would take over?
The BR is obviously an easier build and would seem to be a fair bit more efficient unsurprisingly so I'm thinking this would be the one to go for initially.
I still find the tapped ...thing (horn) an nice concept though, if it can find an application. Maybe of interest to someone someday.
Incidentally the EXP(onential) flare used follows the contour as shown far closer than a parabolic would and gives the correct volume of air too, something that I have found to be an overriding factor in most cases I have simmed.
I have already done as you suggest actually and come up with this:
A decent looking response from a vented cab, IF the cabin gain kicks in as expected around 50Hz. looking at the Infinity plots for their recommended boxes the in car response seems to do just that -but about 60-70hz. However I've been using room mode calculators with the internal dimensions of my van (which is obviously rather larger than most cars) And the longest dimension (front to back) seems to produce a mode at 49Hz. Would I be right in thinking that is where the transfer function would take over?
The BR is obviously an easier build and would seem to be a fair bit more efficient unsurprisingly so I'm thinking this would be the one to go for initially.
I still find the tapped ...thing (horn
) an nice concept though, if it can find an application. Maybe of interest to someone someday.Incidentally the EXP(onential) flare used follows the contour as shown far closer than a parabolic would and gives the correct volume of air too, something that I have found to be an overriding factor in most cases I have simmed.
One more thing I just noticed:
Both of these are shown at xmax (over 30Hz) with the first supposedly giving around 112dB from 30Hz up and the second rising from 115dB at 30Hz to 125dB max.
Even without cabin gain (and as you say 'better to have and not need') I could EQ down the BR above 30Hz to flatten at around 117dB, and still be over the output of the first design.
Guess it's a no-brainer really...
Both of these are shown at xmax (over 30Hz) with the first supposedly giving around 112dB from 30Hz up and the second rising from 115dB at 30Hz to 125dB max.
Even without cabin gain (and as you say 'better to have and not need') I could EQ down the BR above 30Hz to flatten at around 117dB, and still be over the output of the first design.
Guess it's a no-brainer really...
Yes, with the BR being around twice as loud (+5 dB at 30 Hz, +13 dB at 100 Hz) as the more difficult to build TH (which probably won't perform as well as the sim), the choice is pretty simple.
Agreed. Mind you it sounds better than I expected before trying it, the main thing it seems to be missing is a bit of top end, and this is a van after all not my living room.
But I'll be reverting to the aux in (possibly via a JBL MS-2) as soon as I can get round to internally wiring it as I hate cables everywhere- the nexus is already built in the dash.
I reckon improving the sound deadening could be the single biggest SQ issue.
All a work in progress...
Thanks guys, the port shown is just for sim tuningpurposes. Playing with Linearteams online port calculator I have decided to use 3no 30mm ports, I forget the length as im not at a computer at the moment, something like 220mm, HR doesn't sim multiple ports though. I think a 4inch (78cm2) would tirn out to be too long to be practical and use too much chamber volume. Are there any downsides to multiple ports?
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