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Discussion Starter · #1 ·
Hi folks,

Since I've chosen to use full-range speakers + midbasswoofers in my car instead of mids+tweeters, I have 4 5.5" Peerless HDS Exclusive midwoofers and 2 Peerless HDS tweeters 'laying around'.

I was thinking about building a pair of nice compact speakers with them.

According to WinISD, a ported enclosure of about 15 litres tuned at 60ish Hz should do a great job on 2 of those 5.5" Exclusives, what do you guys think?

Then there is the lay-out:
- MTM or TMM or even MMT (upside down TMM), what are the advantages? I like the looks of MTM but what does it do with the sound?
- port at the front or at the back, or maybe at the top/bottom? I see lot's of home-audio speakers have a port at the back, I like that idea (looks), but for car audio subwoofer boxes, I was always told it's best to put the port in the baffle and putting it at the opposite plain of the woofer is the worst thing you can do?

And last but not least: crossing things over:
Should I just keep it simply 2-ways and let both mids play everything untill the tweeter takes over, or should I go 2.5-ways and let 1 mid play midbass+midrange and the other one only help a little in the midbass region?

Please share your toughts, comments and sugestions.

greetz,
Isabelle
 

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Considering both mids are the same and therefore can handle the same frequency range equally as well, I wouldn't bother splitting them up to handle two separate frequency ranges. The HDS woofers have a broad frequency range of ~50 - 3500Hz and the full body HDS tweeters are safe to play down below 2000Hz. If you wish to get much midbass out of the 5.25's, you'll need to keep the power on them down to keep distortion to a minimum and utilize a low pass on the top end to allow the tweeters to take over. Since you will be applying less power to the mids, double the cone area handling the same frequency will aid in boosting the midbass response so you can get away without a subwoofer.

In addition, I prefer port to the front to increase the midbass output.

However, if you plan to run a sub, forget everything I just said lol.
 

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Discussion Starter · #3 ·
Well, that's something I don't know yet.
I don't even know what I'm gonna do with them since I already have a fantastic set of B&W DM2a's.

I have 2 Peerless 12" XXLS (the 'PR' version) subs and 3 Peerless 10" PR's laying around, I'll only use 1 sub in my car, sealed, so I can build a home audio subwoofer with the other one and 2 or 3 PR's.
I also have 2 Soundstream SS8's laying around so maybe I could build 3-ways speakers and use those as basswoofers, but since I am thinking about building something small, I prefer keeping it 2(.5)-ways, with or without a sub.

About crossovers, I was thinking 2.5-3kHz 12dB/oct for mid-LP and tweet-HP wich seems like a point that doesn't stress the mids nor the tweeters, and 60Hz 6or12dB/oct mid-HP to prevent them from unloading below port-tuning.

About the port, I don't like the idea of having a baffle with 3 units in it and a hole below/above/in between them. What if I took a 90° angled piece of PVC pipe with a piece of straight pipe on it to make the length right and shove that in the top of the enclosure so only the angled piece sticks out and the straight piece is inside the box?
I guess that would look pretty cool, but would it work?

greetz,
Isabelle
 

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Discussion Starter · #4 ·
I just played a bit with WinISD and came up with this:
Drivers:
2 Peerless HDS Exclusive 152's

Box:
20 liters (.7 cu.ft.) tuned at 60Hz

Protection filter:
Type: Butterworth: seems to cut off sharper than LR or Bessel so this allows me to reduce cone excursion below port-frequency, without loosing much output just above it
Frequency and slope: 2nd order 60Hz protects fine, 3rd order 55Hz protects just as well, but with less loss just above port frequency, 4th order at 50Hz would even be better, but the difference is small and I don't know how to build a 4th order passive crossover, I know a website that has an application to calculate up to 3rd order passive crossovers...

Crossoverpoint:
I already have speakers that require sitting at the sweet spot to sound good: B&W DM2a's (everything up to 3.5kHz is played by an 8"!).
I want to reduce that effect as much as I can by choosing the crossover point between midwoofers and tweeters at a point where the midwoofers don't beam a lot.
According to the frequency response (831882 | Tymphany), off-axis response at 30° off-axis nicely follows the on-axis response until 4kHz with only a difference of 4dB at that point.
Since the HDS tweeters can be crossed much lower, I'll take the 60° off axis response of the midwoofers also into account, wich seems acceptable untill 2-2.5kHz, wich is also the point where the HDS tweeters start to behave 'flat'.
Since I'll prefer a crossover that is not *too* steep if the drivers allow me, I think I'll go with a 2nd order type so 2kHz might be a bit low for the tweeters at higher volume levels, so I'll go with 2.5kHz.

What do you guys think?
 
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