Big open baffle project

[Pano]

Salut Hugues
A friend of mine in California builds O.B. projects often, and has for 20 years.

His latest project was a big one. 2 Eminence 18" drivers per side for the lows, the Eminence Beta 12LTA fullrange for the mid and ScanSpeak 8200 for the tweeter. (Great tweeter, but the price has gone way up )
All passive filters for everything. Only needs about 100 watt amp to play really loud.

I have not yet head them, but they broke hearts and scared the guys at the last Northern California DIY speaker meet.

I can ask for details if you are interested.

[el`Ol]

Originally posted by MuaDibb
Look at the Bastanis website, this is similar to what you are looking at. From what I have researched people seem to think it is a modified Eminence Beta LT which runs to about 10,000Hz where it naturally rolls off and gets picked up by the tweet. It sits on top of a sub and looks quite nice. I have thought of building something similar.

www.bastanis.com
www.baulsaudio.com

For a Bastanis-like 100dB thing I could also imagine a 12" Beyma. A person in a German forum operated the whizzer out and found the sharp PA-sound was gone.

[hugobors]

I've found a 15" driver with this T&S :

Fs 32Hz
Qes 1,82
Qms 4,04
Qts 1,26
DCR 6,8R
Xmax 3,6mm
Vas 428,78
Mms 98,49
SPL 89dB

I simulate it and gives me 35Hz 0dB whithout EQ, around 10Hz less than alpha 15 with a bigger magnet....

What do you think???

[el`Ol]

I would combine it with Visaton B200 with correction or Ciare HX132, if high sensitivity is not needed.

[hugobors]

So you think it can be a good candidate, maybe better than alpha15"????

[el`Ol]

I`m not sure. Apart from sensitivity Mms is also an issue, especially to have good punch in the 60-80 Hz region that is important for percussive instruments.

[hugobors]

So better with Alpha15, with fs 41Hz???

[el`Ol]

You could contact Rudolf, he is experienced in OBs with bass augmentation and very active in several forums.
http://www.dipolplus.de
I don`t claim to be an expert.

[Rudolf]

Hugues,

a high Qts will give more bass, yes. But Qts as high as 1,26 seems indicative of a rather cheap (=poor?) driver. Since your are prepared to filter actively with eq for bassloss, I would recommend to stay with a driver Qts<0,8.

BTW, smaller magnet usually means higher Qts, but less control of the amplifier on the cone. That probably leads to a unsufficiently subdued resonance at fr, which you don´t want to have.

Do yourself a favour and look more for a sturdy basket and a properly vented motor than for a high Qts. And of course - Xmax is determening how loud you can go.

Rudolf