First speakers - a little ambitious - curved array

[villain3g]

When I finally decided to build a pair of speakers, I knew that I wanted to do something different. I also wanted it to be relatively "simple". The first thought was a single full range driver in a transmission line but they look like conventional floorstanding speakers. My second thought would be a line array but they require a mixer to combat the combing effect. This is apparently due to each driver from center being a little further from the listener’s ear. So I figured, why not have every driver equidistant from your ear. This would create a pretty nice listening experience for focal point.

Keeping cost and final impedance as factors, I went with 16 peerless 2" full range drivers per channel. I arranged them in a curved line array with a radius of 12 ft. I used 3/4" mdf for the sides and internal bracing. Again for cost, I used hardboard for the curved front and back. I wired it up in a configuration to end up with 4ohms. Attached are some pictures.

Originally I was listening to them in a larger room. About 25' wide by 14' deep. In that room they were placed wider apart and I was sitting at the designed height. At first they sounded messy but as I listened longer the speakers started to fill the range. After they had broken in, I was surprised at how deep they were going. I’m not up with all speaker terminology but their presence seemed broad and quite realistic. I tested the speakers with a variety of music. They excelled with acoustic guitar, vocal, and smooth jazz. Where they seemed to fall off is with electric guitar as in heavy metal. The distortion in the guitar is muddled. Maybe I need an equalizer for the different types of music.

Unfortunately I have to move them to my bedroom. They don't have the same presence but its still ok. While in my room played some test tracks through them. I was surprised to hear sound all the way down to 30hz. Now I don’t have any instrumentation to measure the drop-off, but I'd say it was usable down to 40hz.

My next step is to stiffen the enclosure. Any advise from the seasoned veterans would be much appreciated. I plan on doubling the wall thickness to two layers of 3/4" mdf. For the curved baffles I want to use two layers of 1/2" mdf. I think it will bend enough. Flush mounting the drivers and back chamfering the baffle is on the list as well. I'll also round over the edges of the cabinet.

If all goes well with that, I want to incorporate a diy powered sub somewhere in the equation. Either one under a center channel or one under each the left and right speakers.

Quite the lengthy first post. Mostly filled with noobish comments but hopefully you enjoyed it and have some input on the topic. If anything they look sexy...

[villain3g]

55 views and no comments? I’m like Johnny 5... "input Stephanie"... need to know if I’m on the right track. They sound pretty good for the first iteration. Has anyone else had a setup like these?

[slim2fattycake]

love the curve design and the amount of speakers lol. any filters or crossovers? I don't have much knowledge on this. Just wondering.

Are you going to add a finish or leave it like that?

[tonyvdb]

What kind of internal bracing do they have inside? I would be more concerned about getting that right first before concentrating on adding more layers to the outside.
The look is interesting are they ported or sealed cabinats?

[Mike P.]

I'm new to the line array scene but have been considering them. Your design is giving me ideas. I'll need to read up on the curved baffle solution for the combing effect.

What did 32 Peerless drivers cost?

[robbo266317]

A very interesting design, are they all in seperate enclosures?
What sort of filling did you use?

[looneybomber]

If you do rebuild them, get the drivers closer together. The closer the better.

For internal bracing, get a brace that ties the two side walls together and a brace on that back wall...but being that it's curved, that'll help with rigidity.

[villain3g]

All drivers share the same enclosure. The filling is pillow stuffing material from the craft store. There is no crossover but I'm thinking of putting in a high pass filter around 80hz when I get the subs up and running.

In terms of internal structure, there are four diagonal braces. You can see their location in the pictures.

This is by no means the final product in terms of design and finish. I'll play around with port, although I don't think they will be necessary with powered subs filling in the low end.

Cost so far is around 250. My subs will bump that number up significantly. I'll start those in the next couple weeks.

[Mike P.]

What are your plans for subs? Do you have a design picked out?

[looneybomber]

villain3g wrote:

All drivers share the same enclosure. The filling is pillow stuffing material from the craft store. There is no crossover but I'm thinking of putting in a high pass filter around 80hz when I get the subs up and running.

Don't worry about adding a passive HP XO. Your receiver will highpass it for you.

[villain3g]

For subs, I want to incorporate them into the base of each speaker. They will be 8" powered subs. Im hoping to use the Dayton RSS210HF-4:

Specifications:
* Power handling: 280 watts RMS/500 watts max
* VCdia: 2"
* Le: .68 mH
* Impedance: 4 ohms
* Re: 3.3 ohms
* Frequency range: 27 - 1,000 Hz
* Fs: 28 Hz * Magnet weight: 50 oz.
* SPL: 86.5 dB 2.83 V/1m, 83.5 dB 1W/1m
* Vas: 1.14 cu. ft.
* Qms: 3.08
* Qes: .60
* Qts: .50
* Xmax: 9mm
* Dimensions: A: 8-1/2", B: 7-1/4", C: 4-3/4".

Im hoping to use these for both music and home theater. I want to keep the encloseres fairly small and port them as low in frequency as possible. I also want to angle the front baffel to give the illusion that the subs are on axis like the rest of the drivers.

Any recomendations?

[Mike P.]

I want to keep the enclosures fairly small and port them as low in frequency as possible.

This is what a single RSS210HF-4 is capable of. A pair wired for an 8 ohm load could be powered by a 240 watt plate amp. The issue here is not knowing what kind of SPL levels the line array is capable of when crossed over at 80 hz. You would want to be sure a pair of RSS210HF-4's would be a good match in output for the line array.

[villain3g]

so your saying I should build an enclosure for both the subs? My goal was to keep them separate and have the arrays mounted on top. Each sub would be powered by a Dayton SA240 plate amp. They say it puts out 240w at 4ohms.

What program is that? Looks like a valuable tool to have.

Can you recommend a relatively inexpensive testing equipment to find the spl of the speakers?

[Ricci]

It's Winisd. It's free an quite popular. There is also Unibox which is a bit better but you need excel or an emulator. It's free too. there are others as well.

[Mike P.]

so your saying I should build an enclosure for both the subs?

No, the above model is one RSS210HF-4 in 2.5 cu.ft. It would only take 50 watts to reach Xmax with one sub, both could be powered by a single 240 watt plate amp.

[villain3g]

I just ordered a pair of Peerless 830452 XLS 10" Subwoofers and a pair of Dayton SA240 240W Subwoofer Amplifiers. The subs had a much lower frequency than the other ones i was looking at. Down to 19hz supposedly. Im going to start with a simple sealed boxes. Once I get bored with them, Ill add some downward firing ports.

[Mike P.]

What size enclosure are you considering?

[villain3g]

Im thinking 1.5 cubic ft. I tried winISD. It seemed like volume didn’t affect the freq response too much. I pick the dimensions based purely on aesthetics within relation to the speakers. I’ve got the tuned freq to 19hz. That puts the difference in volume from loudest to softest about 6db. I don’t know if that’s noticeable. Is there a better design to get a flat freq response? Can I have a second port tuned to 30hz? Maybe a transmission line or a passive radiator. Have you had any experience with them?

[Mike P.]

You don't have the Re, BL, and the Vas is wrong in your file.

This is 1.5 net cu.ft. tuned to 20 hz with a slot port that is 1" high, 7" wide and 29" long. Input power is 240 watts with a high pass filter at 18 hz.

Here is the driver file, save it to the Drivers folder in WinISD

Peerless 830452.wdr

[villain3g]

now thats a much nicer curve, Thanks!

[slim2fattycake]

Mike's the man. He'll always help out.

[villain3g]

Now I just wish I could get to work... Im kind of on vacation and away from home. It tough having all these ideas in your head and not being able to implement them. Also, I miss listening to my new speakers. Monday will be a fun day.

[ampire]

One of those on its side would make a sweet center channel probably depending on room size.

[villain3g]

The first one was set up as a center until I got the other one finished. It created a strange sensation that the sound was inside my head. Weird but thats the only way I can describe it. Once I get these subs done, Ill make a center channel just like the fronts. Ive been kicking around some bipole/dipole surround ideas. Maybe similar in design to the fronts but have 8 drivers on the front and 8 on the back. I dont know, We'll see.

[villain3g]

Subs are done. They wound up to be about 1.25 cubic ft internal volume with a rectangular port thats 11 x .75 x 33. I filled it with some polyfill and spray glued 1" foam the the interior walls. Theres a brace going from top to bottom and one going side to side. Construction material is 3/4mdf and the front baffel is doubled up. As you can see in the pictures, I was limited in size due to aesthetics. I think the came out well.

The greatest improvement came when i bought my new recieiver. Its a denon 1709. Picked it up for $200. I couldnt pass that up. I chose it not only for the price but it also comes with audessy. I figured i needed some equilization for the arrays to sound right. Overall they sound great. I have them crossed over at 60hz. The bass is well controlled. Not boomy at all. I had a 15" klh sub and these blow it out of the water. There is some port noise. Maybe rounding over the port will solve that. The greatest impact is with movies and explosions. you can feel the bass more so with these that my klh.

Next step is redoing the front and back baffels on the arrays. Then going on to the center channel and surrounds. Also thinking of wiring up a selector switch on the fronts to run them at 8 or 4 ohms. The goal is to run the amp bridged for the left and right arrays.