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Old 8th January 2012, 07:28 PM   #1
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Default Need help designing a 2-way system

Hello all,

Recently, I have been given the task to find a 200 euro-per-speaker compact 2-way system for in our living room.
I have built a couple of subwoofers before, but never a multi-way system. Therefore, I really need some help to do this properly.

First off, I need to explain the situation. In our living room there are two compartments. One compartment is being used as a sitting room and the other is right next to that. Back in the day when my father bought a new stereo set, he was not allowed by my mother to place those speakers in the sitting area, because they were too big. They’re KEF Q7’s connected to a NAD C370 amplifier. Therefore he placed them in the area next to the sitting area. This area later turned into a movie area where the KEF’s are being used as speakers during the movie. At that moment I convinced my dad to get a subwoofer for the special effects so I was allowed to build that. This is a Peerless XXLS-12 Alu 830952 (which, since it is my first, I would now design in a better way).
So last I was home for Christmas and I came up with the idea of placing two small speakers in the sitting area with a high WAF (wife acceptance factor), to be able to listen to music there better. He thought the idea was good and now I’m finding out what is possible.
Since I’ve never built one of these before, I would be thinking it’s probably best to start off with a design that’s ready to be built and maybe adapt that a little bit. I’m not afraid of doing some calculations, since I’m a MSc-engineering student (even though it’s civil engineering), but what I don’t have is measurement instruments. Btw: does anybody have a recommendation for a good book?

So, there are about two methods I can think of:
First is not to use the subwoofer and just place a vented bookshelf speaker. Second is to place a bookshelf speaker with a closed box and use the subwoofer to cover the frequencies below it naturally falls off. The subwoofer is placed in the far end of the movie area, far away from the sitting area. This gives that the low frequencies aren’t ideal in the sitting area, but they are very well spread (volume doesn’t differ a lot from place to place).
My plan is to come up with both designs so he can choose whatever he likes the most. Maybe even a couple of alternatives per design.

The first step would be to select a driver and try to find a kit with it. As it is a big room, I think that an 6,5” driver would be fair, unless there is a very well 5.25” driver or so. So far I’ve found kits that are within budget that have the following drivers:

Scan-Speak: Discovery 18W/8424G00 (Discovery 30)

Seas: CA18RLY (Troels Gravesen), CA18RNX (Seas Mimir, Troels Gravesen), U18RNX (Seas Idunn), L18RNX (Zaph Audio) and the H1333-08/06 T18RE/XFCTV2 (which is a coaxial driver)

Peerless: HDS-134 PPB (Troels Gravesen, 5.25” driver)

Vifa: PL18WO-09-08 (Troels Gravesen), 17-WP-200

Visaton: AL 170 (VIB170 Al, Bijou 170)

For some reason I think the Seas drivers seem the best. I haven’t read a single bad word about them yet. For the closed design, I think the CA18RLY design would be best. However, according to these tests: Zaph|Audio, the actual measured specifications deviate from what Seas give. If I give this a closed design with a Qtc of 0.707, the volume goes up from 20 liter to 40 liters! If I shrink it down to a reasonable 15 liters, the Qtc suddenly rises to over 0.9, so I have my doubts there. Most of the other drivers have their f3’s at around 80-100hz in a closed box. The most ideal speaker would actually be the Seas C16N001/F (E0051-04/06) coaxial driver, but with it being 220 euro’s by itself falls out of budget.
For an open box I really don’t know which driver delivers tight sounding bass which still fills the living room well enough (and goes down to about 40-45hz, since that is the lowest note on a bass guitar). That’s not something you can read from WinISD graphs.

So what do you think? What would be best, or do you have some complete other idea?

As long as the size of the speaker remains small, the sound still remains room-filling, it costs below 200 euro’s and it’s for sale in the Netherlands (see list of stores below), I’m open to any idea what is possible! The goal is of course to beat the KEF Q7’s in terms of audio quality.

Stores in the Netherlands:
Speaker & Co, RumoH - RumoH - Caps, coils and speakers, Speakerland and Europe Audio - Home page

Thanks!

Last edited by masser120; 8th January 2012 at 07:42 PM. Reason: Correction...
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Old 8th January 2012, 07:45 PM   #2
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Think I'd go for something small and cute using the new Alpair 7. For the size, they put out a decent amount of bass, and go all the way up in the treble, without the need for a crossover.

Makes the whole thing nice and simple, with lots of documented projects already out there.

Chris
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Old 8th January 2012, 09:00 PM   #3
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Quote:
Originally Posted by chris661 View Post
Think I'd go for something small and cute using the new Alpair 7. For the size, they put out a decent amount of bass, and go all the way up in the treble, without the need for a crossover.

Makes the whole thing nice and simple, with lots of documented projects already out there.

Chris
Those seem nice too! I'll throw them in there.
Very easy too build that's for sure and pretty cheap compared to our budget. They won't be able to handle high-volumes though, not much more than a couple of watts. But the design would be very compact and easy.

Any other suggestions? Any audible differences between the other drivers? Are there any in between there that may sound a bit warmer (or can you make them warmer)? Why the big difference in specs between the CA18RLY's?
A reason to go for a two way would of course also be to learn from it.
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Old 14th January 2012, 05:45 PM   #4
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How does the Alpair 7 to the Alpair 10?
The latter one is just a bit larger. Large enough to give a better bass response (big room) and to be able to handle some higher volumes than only 90dB (limited bij xmax at least, or am I talking BS right now?). But how are the high's on these? Just as good or close enough? The alpair 10's in the US are about 1.5 times the price of the 7'ns while here in Holland they're about twice the price, si I'm wondering whether it would be worth it.

Stil, how do these small full range speakers compare to a similar priced 2-way system?
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Old 15th January 2012, 07:58 AM   #5
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IMO, a decent FR driver will, through the midrange, beat a conventional 2-way easily.

They do the midrange thing so well that many of the FR guys are happy to let cut down the bass and treble requirements. I added subwoofers
The Alpair 7.3s (latest version) filled a room of 10m by 20m (on ~20w/ch) with bass support (see my sig). Without bass support, the volume would have to be restricted.

The Alpair 10s will be a more capable driver in terms of bass output, though if you want to go reasonably loud in a big room, I'd consider these or the 7.3s, and add sub(s). This is, however, heading away from "compact", unless you could hide the subwoofer...

Chris
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Old 15th January 2012, 01:33 PM   #6
sreten is offline sreten  United Kingdom
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Hi,

A sealed version of https://sites.google.com/site/undefinition/diy/amiga
might be worth considering, both drivers are good value from europe audio
and may be the cheapest combination of quality 6.5" / 1" dome around.

rgds, sreten.
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Old 15th January 2012, 08:28 PM   #7
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Thanks for the answers!
Adding another sub probably won't be an option (allthough it would be usefull). There is already one in the room at the far other side. I could use that, but the distance to the point (or rather area) of listening is pretty far away compared to the location of the speakers.
Volume fortunately doesn't have to be high so the 7's might work.

The Amiga also looks really nice too! I'll throw it in there, thanks.
However: the Dayton RS180S-8 might not be available here, the Dayton RS180-8 is. I'll mail the stores, but will the latter one work also?

I'll tell him the options and I'll here what the answer will be.
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Old 16th January 2012, 05:14 AM   #8
AllenB is offline AllenB  Australia
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Quote:
Originally Posted by masser120 View Post
Adding another sub probably won't be an option (allthough it would be usefull).
If you use more than one sub, you can place them so that the bass blends better with the room. The frequency response will improve, as will the consistency between listening seats.

If you can only use one 'sub', then running full range mains that produce their own bass is almost like having three subs.
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Old 16th January 2012, 09:29 PM   #9
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Click the image to open in full size.

This is a schematic overview of my living room. Middle-left is the sitting area. Right is the movie area and far left is the dining area (which doesn't have to a lot to do with anything).

I've recently changed the position of the subwoofer over to the right, because I feel the sound is better there (also the Peerless XXLS sub still tends to clip at high volumes (making a really load tick...), so I put it closer to the couch (so the volume has to be less) and it doesn't make the closet with glass rattle anymore).

What I could do is place the sub back (another position isn't allowed by the wife of the house) and listen carefully to the bass response. The sub however is aiming towards the right (see arrow) and somehow the bass response on the back of it is a lot less, there is also a big couch in the way of it which seems to dampen the sound.

So as far as it looks I've got two options, either of those with one suboption.
First option is to place the subwoofer back and use it for frequenties below 80 - 100hz. In that case I would need a sealed Alpair 7's or a sealed or small 2-way system.
Second option is not to use the subwoofer and use either vented alpair 7's or vented 2-way system.

Maybe it would also be possible to leave the sub where it is and use it from there. The sound towards the sitting area feels somewhat equal. However, this would mean that the sound is different when you're close to the speakers from when you're further away from the speakers...

What would you think is best?
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