Howdy,
I've been trying to decide on the compromises before I start buying drivers for a pair of OB's as only my third ever pair of DIY speakers. The main sticking point is probably size.
I'd like to go for a 15" (say the ubiquitous Eminence, although I have been thinking Beta rather than Alpha) but it may be too wide for a reasonable baffle size for both fit and WAF. So I've been considering a pair of cheap 12"ers versus a slightly more expensive 12" on its own (say, an Eminence 12).
I'm thinking of a simple full ranger plus woofer(s) crossed down around 150-300 Hz.
A question that has arisen in my mind is the comparison between dual and single woofers. My understanding is that dual woofers will give 3dB more relative output, same Qts, 1/2 the impedance and 1/2 the excursion when compared to a single of the same specs.
However, if the single is nominally ~6dB more efficient, is it mainly the excursion factor that is of concern when comparing? And I guess reduced distortion in the duals due to the cones staying closer to their linear range?
I'd welcome some comments. I'm a real novice on this stuff.
Cheers
Stuey
I've been trying to decide on the compromises before I start buying drivers for a pair of OB's as only my third ever pair of DIY speakers. The main sticking point is probably size.
I'd like to go for a 15" (say the ubiquitous Eminence, although I have been thinking Beta rather than Alpha) but it may be too wide for a reasonable baffle size for both fit and WAF. So I've been considering a pair of cheap 12"ers versus a slightly more expensive 12" on its own (say, an Eminence 12).
I'm thinking of a simple full ranger plus woofer(s) crossed down around 150-300 Hz.
A question that has arisen in my mind is the comparison between dual and single woofers. My understanding is that dual woofers will give 3dB more relative output, same Qts, 1/2 the impedance and 1/2 the excursion when compared to a single of the same specs.
However, if the single is nominally ~6dB more efficient, is it mainly the excursion factor that is of concern when comparing? And I guess reduced distortion in the duals due to the cones staying closer to their linear range?
I'd welcome some comments. I'm a real novice on this stuff.
Cheers
Stuey
Reading your question(s)
I believe it would depend on how low you'd like the system to go (baffle width, driver size, low Fs and highish Qts help here) and how loud do you expect to use them (might be louder than one driver can effectively handle).
Depending on application (room size, wall stand off, 70-80db SPl at the chair) a modest single 12" / FR can still surprise you.
R/
Jim
I believe it would depend on how low you'd like the system to go (baffle width, driver size, low Fs and highish Qts help here) and how loud do you expect to use them (might be louder than one driver can effectively handle).
Depending on application (room size, wall stand off, 70-80db SPl at the chair) a modest single 12" / FR can still surprise you.
R/
Jim
Thanks guys.
I forgot to say in the first post, the duals would be in parallel.
Yeah, I had thought that cone area must give that extra something to the party. I'm verging on getting the 15 and just dealing with how it'll fit in later.
I only occasionally like to crank it up. Most listening is at modest volume. But we all like to show off to the family when they come to see what you've built...
They'd be about a metre (3') from the wall.
I'd like reasonable output at say 40 Hz.
I've even considered the Peerless 830669 like used in the Manzanitas, despite its relatively low Qts and efficiency, as it seems to have acquitted itself well in this project. It does have a low Fs though.
As you've probably guessed, there are budget considerations here too. Big school fees are due for the kids. Mrs Stuey doesn't want me spending on frivolous hobbies right now. So I might even try a single quality 12 on a baffle capable of modification to a dual later on.
Decisions...
Stuey
I forgot to say in the first post, the duals would be in parallel.
Yeah, I had thought that cone area must give that extra something to the party. I'm verging on getting the 15 and just dealing with how it'll fit in later.
I only occasionally like to crank it up. Most listening is at modest volume. But we all like to show off to the family when they come to see what you've built...
They'd be about a metre (3') from the wall.
I'd like reasonable output at say 40 Hz.
I've even considered the Peerless 830669 like used in the Manzanitas, despite its relatively low Qts and efficiency, as it seems to have acquitted itself well in this project. It does have a low Fs though.
As you've probably guessed, there are budget considerations here too. Big school fees are due for the kids. Mrs Stuey doesn't want me spending on frivolous hobbies right now. So I might even try a single quality 12 on a baffle capable of modification to a dual later on.
Decisions...
Stuey
Stuey , even with 4 of those 12inch woofers if I want high SPL in those frequencies below 35Hz ( ie more than 105dB ) I'm going to have to use subs activelly crossed at 40. and then I will need three or four 15inch subs to keep up.
But most of the time I'll probably be happy with 5 watts and 100dB
But most of the time I'll probably be happy with 5 watts and 100dB
What's that from Bunnings; plywood? Or MDF? I was going to use ply as I've had enough of MDF dust for a while.
Regarding the width, I'd already thought the it might not be able to be too much narrower with the 12's to maintain a bit of LF response. Hadn't put a figure on it, but I'd thought any bit narrower would help the WAF. The appearance of a 15 is a bit intimidating, too, for a non-speakerphile missus!
I'm going to knock up a cardboard facsimile 45cm x 100cm and see how it looks, while watching the wife's face...
Thanks fellas.
Stuey
Regarding the width, I'd already thought the it might not be able to be too much narrower with the 12's to maintain a bit of LF response. Hadn't put a figure on it, but I'd thought any bit narrower would help the WAF. The appearance of a 15 is a bit intimidating, too, for a non-speakerphile missus!
I'm going to knock up a cardboard facsimile 45cm x 100cm and see how it looks, while watching the wife's face...
Thanks fellas.
Stuey
If that query was for me, I use 450mm as a compromise between cost, effectiveness and good WAF, and luckily that cheap MDF I posted about earlier is close enough at 440.
Stuey i used to think that MDF on its own was OK, then I thought chipboard and ply, lately I've been using MDF glued to chipboard, and If i want the look of timber a face of Luan ply.
Go for 450 X 900mm or 450 X 1200mm because that is a standard sheet size
Stuey i used to think that MDF on its own was OK, then I thought chipboard and ply, lately I've been using MDF glued to chipboard, and If i want the look of timber a face of Luan ply.
Go for 450 X 900mm or 450 X 1200mm because that is a standard sheet size
No, Ted, it was for gainphile. He mentioned Bunnings standard sheets. I buy my MDF there and wondered about their plywood (I've never looked for it so don't know what sort of quality they have).
Thanks for that info - I didn't know they were the standard sizes.
That MDF of yours is a great find. I bought a big sheet of 25mm from Bunnings which cost $88 - I think it was 2400 X1200. Bloody pricey!
I'm looking at using some decent timber veneer on these. I was looking at about 14" (~35cm) for the 12's, but for the 15's it'll be up around 45 I guess.
Cheers
Stuey
Thanks for that info - I didn't know they were the standard sizes.
That MDF of yours is a great find. I bought a big sheet of 25mm from Bunnings which cost $88 - I think it was 2400 X1200. Bloody pricey!
I'm looking at using some decent timber veneer on these. I was looking at about 14" (~35cm) for the 12's, but for the 15's it'll be up around 45 I guess.
Cheers
Stuey
Stuey the plywood sold by bunnings is simply not good enough for building speakers, quality is uneven, full of voids and the glue isn't that great.
Here in Oz we need to buy the local hardwood Marine grade ply, 12mm is avaiable but if you can afford it go with 16mm, I haven't priced marine ply in a long time.
Here in Oz we need to buy the local hardwood Marine grade ply, 12mm is avaiable but if you can afford it go with 16mm, I haven't priced marine ply in a long time.
Yeah, I have Xlbaffle and The Edge and a few others. I haven't used them much, but I will be now.
I thought Bunnings' ply would be rubbish. Most of their timber is.
I think I can get my hands on the waterproof ply they use on building sites, which I believe is marine ply (used for formworks). Some of my family work in the trade.
I might have to see if that contains voids and is any good. I've got a few offcuts out in the shed and one big one over my pool filter.
Thanks
Stu
I thought Bunnings' ply would be rubbish. Most of their timber is.
I think I can get my hands on the waterproof ply they use on building sites, which I believe is marine ply (used for formworks). Some of my family work in the trade.
I might have to see if that contains voids and is any good. I've got a few offcuts out in the shed and one big one over my pool filter.
Thanks
Stu
Do try the T-bass circuit by Mr. Graham Maynard when the OB is ready.
Now I consider it essential for any OB (dipole) bass.
Now I consider it essential for any OB (dipole) bass.
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