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View Full Version : Enclosure for 8's & 6.5's



ShayneF
10-09-2013, 01:17 PM
I have done a lot of reading on this forum, and like most average music listeners, sometimes this raises more questions than it answers. So I have a lot to get sorted.

My first issue is that I want to build an enclosure to fit two 8inch subs and also two 6.5's as well. I do not want the 6.5's in the rear doors unless absolutely necessary, that will be a last resort. We have a lot of info on here about sub boxes, and I have the specs supplied by Alpine for box size, so that should be a good starting point. But I have not found any info about putting other speakers in the boxes as well.

Home audio speakers do this of course, but a car is a different environment, so the parameters change. So I guess the first question is what is the best option?

A. Enclosure containing 8's and 6.5's
B. Enclosure for the subs, and two separate boxes for each 6.5.

If keeping them separate is the best (or easiest) option, then what info is available for design of a box for a 6.5 mid?

Not sure if this will be relevant at this stage, but I will provide some vehicle and system info below:

I am after sound quality not big power and volume. My old Alpine 6081 subs are only 100w RMS each, and in a previous vehicle they did all I needed. I like a nice balanced sound, and most passengers in my car never knew I had subs until I told them. My last box was sealed and worked well I think. My understanding is that ported boxes need to be very well designed - no margin for error. If I have enough space then I may try ported, but that is not known at this point (see below for vehicle info). If space is not enough then I may have to go sealed again, which I understand allows more freedom of box size to get a reasonable result.

The 6.5's are a Focal split set (75W RMS), rated at . I have a second set of Focal 5-3/8 splits (60W RMS) in the front - mids in the doors and tweeters on the a pillar.

HU : Alpine CDA117E
Sub amp : Alpine MRD501
4 Channel amp: Boston GT4100

The vehicle is not sold in the US (Nissan Patrol), but it will be similar to a Toyota Tundra dual cab when completed. It is being modified from a wagon, so a new rear firewall will be constructed. So at this point exact measurements are not known. Enclosure will go on this firewall behind the back seat, and will house the speakers and have the amps and crossovers mounted there as well.

So what are your thoughts on a single or separate enclosures, and what are the requirements for a 6.5" mid range speaker box?

Cheers,
Shayne

ShayneF
10-11-2013, 05:24 AM
No comments????? Maybe it is a bad idea?

If that is the case I will use a separate enclosure for the subs. Seeing as I don't want to put the 6.5's in the doors, what size enclosures should they be mounted in to operate at their best?

naughtyca
10-11-2013, 08:34 AM
i suggest 2 boxes 1 for sub and the other one for the 6.5, if you can do 4 6.5's, either 1 long box or 2 box with 2 6.5 on each, it will soudn better and look better

run 2 amps, 1 for sub amp and one 4 channel for the 6.5.

bbeljefe
10-11-2013, 08:57 AM
Acoustics on the front side of the cone are indeed different in car audio but on the back side (or, inside the box) they don't change. That said, loudspeaker mids are either closed back or they have their own enclosures inside the speaker box so as to separate the backs of the different driver's cones.

So yeah, you can run the Focal mids in the same box as the subs... just make sure you partition the inside of the cabinet so that different drivers don't share air space.

As for volume for the mids, they're designed to mount in doors or rear decks, which are infinite baffle locations, so you would want a large amount of air space for them. I would think .5-.75ftⁿ if you can spare it.

ShayneF
10-11-2013, 09:19 AM
Thanks for the info. Ok, so separate will be easier to design I think, and keep the subs on their own.

When you say .5 -.75ft I assume you mean cubic feet for each mid? Isn't that a lot less than the average door? Would more be better, given that doors and decks aren't sealed?

Now you have me wondering whether they need to be mounted in something open. :confused:

bbeljefe
10-11-2013, 09:43 AM
Thanks for the info. Ok, so separate will be easier to design I think, and keep the subs on their own.

When you say .5 -.75ft I assume you mean cubic feet for each mid? Isn't that a lot less than the average door? Would more be better, given that doors and decks aren't sealed?

Now you have me wondering whether they need to be mounted in something open. :confused:

Yes, more would be better but I was recommending minimums. And you don't need them in an open enclosure... just a large one.

If Focal publishes the TS parameters for these drivers send me a link to it and I'll be happy to model some ported enclosures for them.

ShayneF
10-11-2013, 09:56 AM
Sorry for my ignorance, but a "TS parameter" is something I have not heard of before. I have some specs for them, but nothing that sounds like that.

sweety
10-11-2013, 01:33 PM
I own a Nissan Terrano 2.7 TDI R20 again not sold in the US, I replaced the 5x7" speakers with 6.5" up front & 5.25" in the rear doors which was quite easy once I made up some MDF baffles & ao run a 10" sub in the back. Not sure if this helps any;) Love the Patrol just can't aford to run one with the UK fuel prices at 6 British pounds a gallon & it's going up again:rage:

ShayneF
10-12-2013, 12:04 AM
The Patrol doors are not a good spot to mount speakers in due to the profile of the door and the seating position of the passengers. Manual window winders also get in the way, but I do not like electric windows in 4WD (4X4), as dust and vibration eventually stuffs them. So the rear doors are an absolute last resort. Not a good idea.

I am wondering though whether my plan to put them in an enclosure on the rear firewall is a bad idea. I have the 5-3/8 mids in the front doors, which work well. But with the frequencies that the 6.5 mid will put out, I am concerned that if they are partly obscured then the sound will be compromised.

Any thoughts on this guys? Where would you put them?

ShayneF
10-12-2013, 01:21 AM
Hey bbeljefe, I just found an old post of yours where you mounted a sub in a custom console. Great idea and a great job!

Be a nice spot to mount my 6.5 mids to keep them out in the open for sound quality, but I think volume would be too small from what you told me.

bbeljefe
10-12-2013, 03:51 AM
TS stands for Thiele Small and essentially, those are the numbers one needs to determine the amount of air space and type of enclosure a given driver will work best in.

Personally, I don't like the idea of sound coming from the rear or, any rear fill at all. Bass isn't localizable so sub placement isn't critical but to create an accurate sound stage, the midbass and up drivers should be in front and, in a perfect world, at ear level to the listening position.

If it were me, I would concentrate on deadening the front doors and getting the most I could from that location and I would forget about the rear fill. I also wouldn't mount mids in a console, as it will cause time delay issues that will complicate stereo separation.

And thanks for the nice words. :-)

calebkhill
10-12-2013, 07:44 AM
Those speakers mounted back there will take away any SQ you hope to get.
Think about it... Speakers.... behind you.....

ShayneF
10-12-2013, 11:16 PM
I found those specs actually, didn't think I would but I got lucky. This is copied from another forum.

Fs: 83.24hz
Vas: 0.242 ft3
Qts: 0.83
Qes: 0.9
Qms : 10.72

Speakers in the rear is something I am used to, because most basic installs like factory stuff do it. But I know that when I look at most professional installations that you never see it. They always try to get the sound stage up the front. No doubt the best option if you can do it.

I have the 5-3/8 mids in the front doors. Would there be any advantage to putting the 6.5's next to them? Not sure if it can be done with my vehicle though. Last vehicle they were in the rear doors, but I guess that would be about equivalent to putting them in the console.

calebkhill
10-13-2013, 12:16 AM
best to replace the current ones with 6.5's

bbeljefe
10-13-2013, 10:12 AM
If you can, replace the 5.25" mids in the doors with the 6.5"s.

ShayneF
10-14-2013, 01:02 AM
I had to do a fair bit of work to the doors to get the 5-3/8's in there. I had to cut some steel out and weld some back in, move the window track a bit, and make a spacer for them, and there is no room in the cabin to build a pod that sticks out. The 6.5's are a lot bigger so I don't think it is possible to fit them in the same spot.

This vehicle is a bit unusual in some respects. It is a big vehicle, but the cabin layout is not spacious due to a very large trans tunnel. There is not even room to fit a crossover in either of the kick panels!

ShayneF
10-14-2013, 01:02 AM
I had to do a fair bit of work to the doors to get the 5-3/8's in there. I had to cut some steel out and weld some back in, move the window track a bit, and make a spacer for them, and there is no room in the cabin to build a pod that sticks out. The 6.5's are a lot bigger so I don't think it is possible to fit them in the same spot.

This vehicle is a bit unusual in some respects. It is a big vehicle, but the cabin layout is not spacious due to a very large trans tunnel. There is not even room to fit a crossover in either of the kick panels! So I have some restrictions to what I can do. This is a 4x4 so it has a lot of design built into it for that purpose, such as a compressor mounted under the rear seat etc, so it is not a dedicated audio build like a lot of members of this forum do.

Unfortunately, I just can't do what would be the best option, so I have to compromise. My head unit has time correction ability, so I will have to mount them in the rear I think, and use settings to get the best out of them. So a rear enclosure foe each one, mounted up above the rear seat height, might be the best option.

Would time correction issues be much different between the rear firewall and the console? Maybe the console idea is still a good one.