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-   -   Before I start out, I need some direction (http://www.diyaudio.com/forums/multi-way/103721-before-i-start-out-i-need-some-direction.html)

buggsson 17th June 2007 11:46 PM

Before I start out, I need some direction
 
I need some advice so that I know which direction to take with my project (my first).

1. CAE software: I know, I guess this has been up many, many times but my searches came up with nothing about SPEAK. The only alternative that is reasonably cheap that can handle 5 drivers on the baffle is SPEAK, as far as I know. I don't know about lspCAD Stnd, but lspCAD Stnd seems to be too limited in features. Anyone who has used SPEAK? Is it any good? What about support, I sent an enquiring e-mail some weeks ago, still no reply? Speaker Workshop is not an option. Maybe I want too much?

2. What is the easiest to implement, a three-way speaker or a two-box solution with a sub unit that has a two-way on top of it? I was thinking the two-box, then it will be easier to do changes/upgrades in the future?

My plan is using four, or maybe two 10" or 9" woofers in isobaric configuration coupled in push/pull. Any reason to have one vs. two chambers in the sub-box?

3. Can I concentrate on the sub-box and leave the two-way for later?

4. I have considered the following woofers:
Dayton RSS265HF-4
Scan-Speak 23W/4557T00 9"
SEAS Excel W26FX001 E0026
SEAS Prestige L26RFX/P H1209
because: Fs lower than 25 Hz, no PP-cone, no foam surround, EBP not much higher than 50.

5. The room is 30-35 m^2 and 2.26 m high, and opens up to an additional 10 m^2.

6. The test box, what is mandatory of a test box, that is, how close to the final box does it have to be? Which factors are of importance?

planet10 18th June 2007 04:19 AM

Re: Before I start out, I need some direction
 
Quote:

Originally posted by buggsson
2. What is the easiest to implement, a three-way speaker or a two-box solution with a sub unit that has a two-way on top of it? I was thinking the two-box, then it will be easier to do changes/upgrades in the future?
2 way with a sub is easier i'd say. Even easier is a 1 way with active sub.

dave

maxro 18th June 2007 08:41 AM

Er, Planet10, perhaps you could move this into the general loudspeaker forum and out of the fullrange section. I suspect more replies will come of it.

planet10 18th June 2007 07:15 PM

Quote:

Originally posted by maxro
Er, Planet10, perhaps you could move this into the general loudspeaker forum and out of the fullrange section. I suspect more replies will come of it.
Good idea... done

dave

sreten 19th June 2007 10:17 AM

Hi,

In a 2 way + sub all BSC correction is done in the 2-way.

In a 3 way the options for BSC implementation are numerous, most
of these options are not understood (e.g. partial BSC in the mid
driver + some back up from the bass unit), depends on the drivers
used and are impossible to design without decent simulation before
the drivers are chosen (IMO).

:)/sreten.

buggsson 21st June 2007 02:39 AM

So I guess that I will stick with a sub + a two-way system.

For the sub section, any advantage/disadvantage to have one large chamber for all four drivers, or two chambers for each pair? (If I will need all four drivers for desired response, output etc)

I really would like some input about CAE software an in 1. Especially if anyone have had experience with SPEAK. Sure, I can use it in demo mode, but I would like some input from someone knowledgable that has had experience with it. Now that I have decided on the major design of my project, I need to decide on which software to use, so that I can start some simulations to pick the drivers.

For now, I plan to go active all the way.

I have started to collect info about what other DIY folks say are nice tweeters and midwoofers. What are you to look for when matching a tweeter to a midwoofer, more than that they have some overlapping frequency responses?

sreten,
what is BSC standing for? Audio lingo can be hard as it is, abbrivations even harder..........

planet10 21st June 2007 07:42 AM

Quote:

Originally posted by buggsson
For the sub section, any advantage/disadvantage to have one large chamber for all four drivers, or two chambers for each pair? (If I will need all four drivers for desired response, output etc)
Build 2 push-push subs. Stereo woofers have big advantages over a single woofer. And push-push is even more advantageous.

Quote:

really would like some input about CAE software an in 1. Especially if anyone have had experience with SPEAK.
I can't recall ever running into anyone using SPEAK... the high price is a deterent for most diyers.

Quote:

what is BSC standing for?
Baffle Step Compensation

http://www.t-linespeakers.org/tech/b...intro-bds.html

dave

sreten 21st June 2007 02:13 PM

2 Attachment(s)
Hi,

Attached are basic sims of two Daytons in a box.

Due to your driver selection criteria vent tuning frequency is low.

If the boxes are too big you could consider one driver with 1 or
2 passive radiators per box. Note that a mono sub amp driving
two seperate boxes gives better room drive than one box.
Its very arguable about having "stereo" low bass.

Personally I'd go sealed two box push push with those sort of drivers.
Sub amplifier with adjustable low bass boost would be a good idea.

:)sreten.

buggsson 22nd June 2007 02:57 AM

I don't know if I wasn't clear enough initially, but my plan was/is to build two sealed subs, isobaric and coupled in push/pull, using either two or four drivers per sub.

I am mearly brainstorming at the moment and the knowledge is scarce, so my view was that going with the rather smallish 9" or 10" drivers, I might be able to get a desired SPL or whatever, using four drivers rather than two per sub. I really do not know what I need in my room, I just felt that I had to start somewhere.

Would four drivers per sub be overkill?

Regarding SPEAK, as far as cost is a consideration, it is, but it is the least expensive software I have encounterd that can handle 5 drivers on the baffle, which is where I want to go, eventually.

I have read the link about BSC and it was interesting reading, but digesting it will be a while. I'll learn as I go along.

Box size is certainly an issue, so they cannot be to large, the dreadful WAF is a powerful force, and I am surprised that I got the OK for this project. My former speakers was a pair of Totem "Sttaf" and they were rather large, I was told. I would guess 50-60 litres for the subs would max it.

sreten, thanks for the graph. Is the different Qtc values due to varying box volumes? Is the responses to strive for, similar to the green response? Name of the software?

After all this time, it feels like I have finally begun. Software next so that I can mess around myself a bit.

What determines how low your speakers will go? I mean, I have a couple of 12" drivers I've been looking at, but they do not have much different Fs values, all else the same, would they by any reason what so ever, go lower than the 9" and 10"? If not, the smaller drivers will give a smaller box, and therefore higher WAF.

sreten 25th June 2007 09:27 AM

Hi,

Going isobaric halves box volumes and doubles amplifier power and driver costs.
Basically will not do anything for bass extension or maximum levels.
Given the sort of drivers your considering, isobaric is not a good idea.

Push Push in force cancelling mode is your best bet, 50 to 60L per pair.

Qtc depends on box volume and stuffing, target 0.6 to 0.7 IMO.

Green is not the target, red is better but these are vented, not sealed.

Basically the bigger drivers in bigger boxes will go louder, with similar
parameters the smaller will go as low in smaller boxes but with lower
efficiency.

Sub amplifier with adjustable low bass boost would be a good idea.
This will determine "how low they go".

Try Win ISD PRo or some other sub simulator.

:)/sreten.


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