RobWells said:
Like I said, you decide on the trade-offs and build what works best overall for your app. I have no experience with such an extreme BP alignment, but it's not one I'd even consider. The few I've done for others were low Q 4th order with a rising response and could be EQ'd flat enough with just the receiver's bass control. Not the last word in HIFI, but hardly one note boomboxes either that seem to pervade car audio.
Note that TPs/THs can be EQ'd somewhat with damping.
GM
Haven't tried to draw it out, so don't know how much effort it will take to make the drivers fit, but the Peerless in a clamshell isobaric can be tuned low with obvious rising response and a big dip around the cabin gain peak with some much needed gain above it in ~81.33 L plus all the internal baffling. Since isobaric doubles Xmax, the SPL is more than enough if you have a 200 W amp into 2 ohms. The peaking at Fp can be damped if it's obvious/objectionable:
GM
GM
Attachments
hi Eva - ya ever build Karlson boxes? - heres a forum to discuss K's
http://gainclone.com/Karlson/index.php?board=1.0
Freddy
http://gainclone.com/Karlson/index.php?board=1.0
Freddy
Hi GM,
That peerless horn does look like it would fit the cabin gain well.
I'm going to build a BP with the perfect 12.1's, and also have a look at building that horn aswell.
It will be interesting to see how they measure up to the sims.
Thanks for all the help so far GM and Eva.
Really appreciated.
Rob,
That peerless horn does look like it would fit the cabin gain well.
I'm going to build a BP with the perfect 12.1's, and also have a look at building that horn aswell.
It will be interesting to see how they measure up to the sims.
Thanks for all the help so far GM and Eva.
Really appreciated.
Rob,
Eva said:
Hmm, in my haste/whatever I see I over simplified to the point of misleading, sorry!
Down low, the increased box stiffness of isobaric yields a higher acoustic efficiency, i.e. greater gain for a given excursion, but as compliance increases with increasing frequency the gain rolls off, so the sim's rising response will flatten out on the top end. Hopefully not so much as to cause a major broadband dip in the in-SUV response.
GM
Ok I've finished up on a quick test box for the bandpass box.
Following are ground plane vs winISD model, a couple of pics of the box (yes it's ugly but made from off cuts etc..) and a groundplane vs in car plot. Looks like the huge dip at 60Hz is an acoustic problem, not something eq will fix.
Hopefully my mains will work down to 60Hz or so and fill in the gap.
Will do a test box for the tapped horn next and then take a break until my main speakers are fitted and measured.
Cheers,
Rob.
Following are ground plane vs winISD model, a couple of pics of the box (yes it's ugly but made from off cuts etc..) and a groundplane vs in car plot. Looks like the huge dip at 60Hz is an acoustic problem, not something eq will fix.
Hopefully my mains will work down to 60Hz or so and fill in the gap.Will do a test box for the tapped horn next and then take a break until my main speakers are fitted and measured.
Cheers,
Rob.
Attachments
Be careful because the front chamber becomes easily detuned inside the car. Are you connecting the ports to the cabin? You have to tune it in the final mounting arrangement and it will always ask for a shorter port than expected. Any surface near the front port mouth will reduce Fb and Q drastically.
If both measurements were done with the same scale, then note how higher frequencies become attenuated inside the car. There isn't a dip at 60Hz, it's just that everything becomes 10dB attenuated above 60Hz.
If both measurements were done with the same scale, then note how higher frequencies become attenuated inside the car. There isn't a dip at 60Hz, it's just that everything becomes 10dB attenuated above 60Hz.
Hi Eva,
The vehicle is like a large estate so there is no seperate boot to cabin. The box was placed behind the rear seats.
It's looking like I'm going to need a couple of parametric EQ's. Any ideas on good value used models?
I'm thinking I might get away with a phoenix gold basscube but it is only a single channel, boost only eq with 2 Q settings, wide and narrow. I'd have to use boost in the 60Hz region to do this.
Am also open to trying a small 8" sub in the glove box to do 40 - 120Hz with a very large box in the boot. I'd have to remove this completely and just use the 8" when camping.
Have started to make the tapped pipe this week.
Cheers,
Rob.
The vehicle is like a large estate so there is no seperate boot to cabin. The box was placed behind the rear seats.
It's looking like I'm going to need a couple of parametric EQ's. Any ideas on good value used models?
I'm thinking I might get away with a phoenix gold basscube but it is only a single channel, boost only eq with 2 Q settings, wide and narrow. I'd have to use boost in the 60Hz region to do this.
Am also open to trying a small 8" sub in the glove box to do 40 - 120Hz with a very large box in the boot. I'd have to remove this completely and just use the 8" when camping.
Have started to make the tapped pipe this week.
Cheers,
Rob.
Hey I may be able to help, car auido is one of my specialties. When you model your stuff in winISD, remember that there is cabin gain. You can simulate it by assuming the car behaves as a leaky sealed box. Do it with a linkwitz transform, Both Qs will be 0.707, and the frequencies will depend on the vehical, in my case 20Hz and 60Hz.
I find that designing a flat box in winISD will sound bloated, and have an exagerated low end once its in a car.
This is a simple parallel tuned 6th order bandpass for 2 crappy audiobahn subs.
The end result was a clean sounding pretty loud system.
The ports are adequate, there is no port noise until just before the subs reach xmax...its an audible indicator to turn it down.
Its for in a truck.
If you can, try a tapped horn. Have it load against the rear of your vehical, essentially extending the horn mouth.
Hmm..thats all. I hope it helped a little.
PS I have had alot of luck with tang band 8s and passive radiators in open vehicals, by loading it off the hatch. a .8cuft box with a 12" radiator work really well. It was tuned to 34Hz
I find that designing a flat box in winISD will sound bloated, and have an exagerated low end once its in a car.
This is a simple parallel tuned 6th order bandpass for 2 crappy audiobahn subs.
The end result was a clean sounding pretty loud system.
The ports are adequate, there is no port noise until just before the subs reach xmax...its an audible indicator to turn it down.
Its for in a truck.
If you can, try a tapped horn. Have it load against the rear of your vehical, essentially extending the horn mouth.
Hmm..thats all. I hope it helped a little.
PS I have had alot of luck with tang band 8s and passive radiators in open vehicals, by loading it off the hatch. a .8cuft box with a 12" radiator work really well. It was tuned to 34Hz
Eva I have read the whole thread. Even the cabin gain stuff. I thought mentioning WinISDs ability to model cabin gain would be helpful.
Sorry if my post was a waste in your thread Rob.
By the way what levels of SPL are you looking for? If they are modest I am sure you can reach the levels with a simple ported box. I know it doesn't give you as much control over the frequency response, but BP can act much differently than predicted once they are placed in a car.
IMHO I can get an acceptable ammount of SPL and bandwidth from one 8" tang band in a passive radiator box. This is coming from a guy with 2 18s and an amp that puts out 117V RMS(and is stable down to 1 ohm ).
Anywho just PM me or something if you want me to stop posting. Just thought I'd put out another perspective.
Sorry if my post was a waste in your thread Rob.
By the way what levels of SPL are you looking for? If they are modest I am sure you can reach the levels with a simple ported box. I know it doesn't give you as much control over the frequency response, but BP can act much differently than predicted once they are placed in a car.
IMHO I can get an acceptable ammount of SPL and bandwidth from one 8" tang band in a passive radiator box. This is coming from a guy with 2 18s and an amp that puts out 117V RMS(and is stable down to 1 ohm
). Anywho just PM me or something if you want me to stop posting. Just thought I'd put out another perspective.
Hi Judtoff,
SPL wise a single 12" sealed would be fine. I was looking at BP's as a way of having the drivers safe from harm and this thread has developed from there....
Originally I was going to build my 2 infinity's into the rear trim panels 1 per side. Then I started thinking about the reasons I bought the vehicle and decided that the drivers may be vulnerable in that location, and also their grills would often have stuff blocking them. So I looked into a BP that had response like the sealed etc etc.......
I've also been looking at trying some different box types.
I'm still going to build a tapped horn to try aswell. Pretty certain it's going to be the isobaric one GM posted for the peerless drivers earlier.
I'm starting to think that an 8" sub in my glovebox up front is a good idea as it leaves the rear for camping gear etc, and then I could put a large pair of boxes in the back that have a quick release so I can remove them when I go away camping etc..
ie some usable sub all the time with some big bass for when driving around at home.
It's my 2nd vehicle btw - run a small car for commuting, so I'd like it to have a fun system in it.
Cheers,
Rob.
SPL wise a single 12" sealed would be fine. I was looking at BP's as a way of having the drivers safe from harm and this thread has developed from there....
Originally I was going to build my 2 infinity's into the rear trim panels 1 per side. Then I started thinking about the reasons I bought the vehicle and decided that the drivers may be vulnerable in that location, and also their grills would often have stuff blocking them. So I looked into a BP that had response like the sealed etc etc.......
I've also been looking at trying some different box types.
I'm still going to build a tapped horn to try aswell. Pretty certain it's going to be the isobaric one GM posted for the peerless drivers earlier.
I'm starting to think that an 8" sub in my glovebox up front is a good idea as it leaves the rear for camping gear etc, and then I could put a large pair of boxes in the back that have a quick release so I can remove them when I go away camping etc..
ie some usable sub all the time with some big bass for when driving around at home.
It's my 2nd vehicle btw - run a small car for commuting, so I'd like it to have a fun system in it.
Cheers,
Rob.
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