Which drivers for my next open baffles?

[CLS]

The Eminence APT tweeter sounds quite good. It does not has those exteme details in treble like drivers with metal diaphragms, but very smooth and can extend quite high.

Choose a proper mid to work with it though. APT can not sing very low, only 3.5~3k with 2nd order xover I think.

You may get it with lower price elsewhere. Within its limit, you can't go wrong with it.

 

[fredex]

To Gary P

Hey thanks for the great DIY photo! Tells a story, nice looking work in progress, a Sonic Impact, drill etc etc. Makes me want to do something!

Cheers

 

[SimontY]

Gary, that's one purposeful looking speaker!

Pan: yes, I want that one!

I cannot easily fit a 15" woofer in, never mind two, which is how I arrived at 12 + 15" - it was the way to get the most possible driver in my small room.

But it looks like 2 x 12" is probably more sensible, and easy to move around etc.

I think I'll order these drivers today

Thanks for tweeter comments guys, I'll try this as it's something very different and I can see a PA horn tweeter coming closer to real cymbals and triangles than the typical dome... and for a cheap price. I can always swap it out later and put in a Seas Excel etc.

I've always been curious about PA drivers, mainly woofers, because some clubs sound so fantastic.

Simon

 

[SimontY]

I'll look for the Hi-Vi tweeter but I suspect $100 might translate to £100 and for now, that's out of my budget. I have a lot of drivers to buy and limited funds.

Ooh, they're only £60 + vat actually, not terrible for what looks like a very impressive driver. It will have to wait though.

Never seen this shop before:
http://www.bmm-electronics.com/Product.asp?Product_ID=6968

Simon

 

[SimontY]

The initial driver line-up, unless someone tells me today it's flawed, will be:

* Eminence APT-80 horn-loaded tweeter (£16.65)
http://www.amazon.co.uk/Eminence-AP...3?ie=UTF8&s=electronics&qid=1227089939&sr=8-3

* Eminence Beta 8 mid (£33.03)
http://www.amazon.co.uk/Eminence-Be...6?ie=UTF8&s=electronics&qid=1227090097&sr=1-6

* Eminence Beta 12LTA (£39) (x2)
http://www.amazon.co.uk/Eminence-Be...7?ie=UTF8&s=electronics&qid=1227090097&sr=1-7

The spec of this woofer is the best I've seen for a 12" destined for an open baffle:

* 97.7dB (96 in the bass!)
* 45hz Fs - not ideal but I think it could be reduced
* 0.51 Qts - in the ideal range I think
* 3.2mm xmax - should be plenty with 4 in a small room

Simon

 

[Moondog55]

Looks good on paper' and running the woofers in parrallel will give reasonable power handling, have you modelled running woofers in series?? lose 3db but perhaps worth it to lower "Q" on second woofer.
Just a thought perhaps not even workable.

 

[SimontY]

Looks good on paper' and running the woofers in parrallel will give reasonable power handling, have you modelled running woofers in series?? lose 3db but perhaps worth it to lower "Q" on second woofer.
Just a thought perhaps not even workable.

Hi moon,

I've not modelled anything yet! The drivers should work based on others using them and the specs (so I hope ).

Now then, why would I want to lower the Q? Qts=0.5 looks about good to me. My current ones are 0.4 and I'm "getting away with it". These will run on a slightly wider baffle with slightly longer wings.

Also the series coil will be massive if I make the woofers 16 ohm, I can't quite see your thinking here yet. Another plus of parallel is the whopping output it'll give, which will make matching to the other, high efficiency drivers, easier. This should make for a high efficiency open baffle with big output and cracking DYNAMICS.

I will start a new thread for the speakers, shortly, which I'll try to keep as a neat, short thread!

Simon

 

[Moondog55]

WHOOPS, my mistake Thats "Raise Q " by adding the resistance of the preceding woofer . Sorry I keep forgetting that you are going passive with this.

 

[SimontY]

WHOOPS, my mistake Thats "Raise Q " by adding the resistance of the preceding woofer . Sorry I keep forgetting that you are going passive with this.

I think a coil to roll-off the woofers (high-pass) at about 100hz should get some decent bass, and then comes in another 6dB at resonance courtesy of T-Bass.

I will look at active (well, hybrid active/passive) later but I can't honestly cope with that much change at once. I need to get a project moving by starting with things I understand first.

FWIW I think the benefits of active are diminished a bit in an open baffle, because you no long need to control the woofers so tightly as you do in a box.... OB still works with high DCR coils in series. And a low-DCR ferrite cored coil is cheap anyway. For über-quality a transformer type inductor might be ideal... and a nice 300VA toroid for each T-bass cct.

Simon

 

[Moondog55]

Yes Graham sent me the details of his "T-bass" circuit, while it looks good I don't think my woofes will benefit as much as some low "Q" drivers.
I'm trying to think of an arrangement that will allow me to use 4/6 woofers per side in a WAF factor =1 baffle, may have to investigate these "Ripole" arrangements.

 

[SimontY]

Those look good but they do force a low crossover point, due to resonances.

 

[Stuey]

..........in a WAF factor =1 baffle.......... [/B]

Hmmm...my issue exactly. I discussed (with Mrs.) the baffle width needed for a 15" or two, and just got that LOOK...I'm sure you know the one...?

I'm even more interested now Simon! The Alphas aren't available here in Aus, but the Beta 12's are. We're cursed by a small-ish market here.

How do you reckon one 12 per channel would cope? (Not sure I can extend to two at this stage, just before the Christmas purge of my wallet).

Keep up the rapid progress!

Stuey

 

[SimontY]

Hmmm...my issue exactly. I discussed (with Mrs.) the baffle width needed for a 15" or two, and just got that LOOK...I'm sure you know the one...?

I'm even more interested now Simon! The Alphas aren't available here in Aus, but the Beta 12's are. We're cursed by a small-ish market here.

How do you reckon one 12 per channel would cope? (Not sure I can extend to two at this stage, just before the Christmas purge of my wallet).

Keep up the rapid progress!

Stuey

It depends how loud you like to listen and how far you sit from the speakers. I currently use 4 x 7" (must be roughly a little more than 1 x12") and I have to play it stupidly loud to make the woofers reach high excursion, and to make the mid unhappy. I've never heard loud distortion noises from any of my drivers, which flies in the face of people saying a mid needs to be steeply filtered and you need loads of surface area on the woofer..

So I'd say it comes down to the size of the room, your distance from the speakers and how loudly you play. If the room's not huge and you don't play loudly and don't intend to do crazy EQ a single 12" could work nicely IMO.

Simon

 

[Moondog55]

HMMM!!!!!!!!!!!!
THE "LOOOK" pursed lips, squinty eyes crooked nose?
Not usually but when I started measuring a baffle 2200 X 960 in the loungeroom, yes I know the "LOOOK"
Actually tha baffles would be the same size as a pair of Ikea bookshelfs and we already have 4 of those, i have a maximum size i'm allowed it's 1800 X 720mm and no deeper than said bookcases

 

[SimontY]

HMMM!!!!!!!!!!!!
THE "LOOOK" pursed lips, squinty eyes crooked nose?
Not usually but when I started measuring a baffle 2200 X 960 in the loungeroom, yes I know the "LOOOK"
Actually tha baffles would be the same size as a pair of Ikea bookshelfs and we already have 4 of those, i have a maximum size i'm allowed it's 1800 X 720mm and no deeper than said bookcases

lmao

Seriously though, most people can only get away with baffles/speakers half that size!!!

Simon

 

[Moondog55]

Cecile (SWMBO) likes music and "da BASS mon gotta hab de BASS"

I'm seriosly thinking of using my quad of Vifa P13's with these woofers and using the P11's in the "Blackwood" clone

 

[croat47]

Goldwood for Bass?

Simon,

Been following this and your dipole experiment. Thanks for the open development and to all who have saved me future funding waste. Perhaps I am crossing my threads, but were the Goldwood drivers mentioned somewhere?

A pair of these could get you to 90dB. And an F3 around 40Hz with a 12" baffle. That is my estimation though.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=290-325

The price is right. There is also a 4-ohm version at the same price that is listed as 91dB efficient. Running them series does not buy you SPL, but gets you more SA.

http://www.parts-express.com/pe/pshowdetl.cfm?&Partnumber=290-320&scqty=2

 

[SimontY]

I didn't mention Goldwood but they do tend to come up in these OB threads!! They have wonferful OB specs but could they sound "tight" and detailed?

My main problem is I'm not prepared to order from the States - it takes too long to arrive, costs a packet in shipping and you can get stung for import duty. You're lucky having cheap and easy access to parts like that IMO!

Simon

 

[Pano]

Glad to see that Gary P chimed in.
It's the Beta 8A drivers in his system that impressed me so!

Gary has a clean, clean, super clean system going there.
Proabably the cleanest dynamic driver system I've ever heard, and that includes some of the multi kilo-dollar systems on the market.

Not sure about using the Beta 12 LTA as your woofer. You may have to EQ the hell out of it. I have heard it used as a midrage with an 18" woofer. Sounded great that way.

 

[SimontY]

Not sure about using the Beta 12 LTA as your woofer. You may have to EQ the hell out of it. I have heard it used as a midrage with an 18" woofer. Sounded great that way.

I was hoping just T-bass would do, with a good baffle including wings. And of course ultra-low crossover with just a coil/inductor/choke - this would counteract the falling response and I feel there's plenty of energy to throw away like this.

Do you have any better ideas for a 12" woofer? I'm close to ordering, getting itchy fingers. FWIW I am hearing great sound from my 7" woofers, and no active EQ. I intend to take this new design further, and the 12" LTA can only be better (bigger, higher Qts).

Simon