Altec pro-audio

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
Inductor

Inductor

Member
Joined 2006
GM said:

OK, but by itself doesn't mean much ;):
Click to expand...

So, ...you didn't designed the xover, and you are considering RC dampers and damping resistors already...? :dice:


As I am entering the 8W SET world I am looking for suitable drivers and although I have not eared yet any lowther one, their graphs seem a bit "unstable" at lower/mid regions undoubtedly with very nice SPL's. carcass :eek:
Click to expand...
 
GM

GM

Member
Joined 2003
Greets!

I miss your point. I mean the 8BX already has an XO and the SET's high output impedance will add a broadband hump in the response centered around Fs to help with baffle step loss, while the rolled off LF extension will help blend it to the room somewhat.

GM
 
C

carcass

Member
Joined 2006
arqz.net
Inductor said:

(...)to have some control on the impedance peak and Zmax you might have to shift the resonance upward by a predictable amount, ie. Fb@50 Hz. /B]
Click to expand...


As in changing the box properties (or xover?!) ? or am I loosing some, I guess that graph from GM was a TL ?

Only thing I have here is winisd :xeye:

Gotta grab those martin spreadsheets (and learn how to use them :D )

Bruno H.
 
Inductor

Inductor

Member
Joined 2006
carcass said:
As in changing the box properties (or xover?!) ?
Click to expand...

Any of them, we are only discussing speaker driver. If it pleases you for me it's fine. Is not a bad speaker after all. Not that it's the one I got. I got a plain 10" woofer, and I have another 12" high efficiency with Fs60Hz. It's a PA wide range but this is mounted in a bass horn what is just fine.

The coaxial (Beyma 8"BX) centrality it's a bonus.

carcass said:
Only thing I have here is winisd :xeye:
Click to expand...

It's really fine. You play with Xmax at the impedance peak of 50 Hz and see what the maximum power (Wrms) it says it can handle. Since you are not using it all (at full power)... We are talking about a Beyma 8"BX coaxial, you can use it in WinISD. Adjust the vent if you are using it, I am not sure.
 
GM

GM

Member
Joined 2003
Inductor said:


it doesn't have one, ...you have to buy...
...to have some control on the impedance peak and Zmax you might have to shift the resonance upward by a predictable amount, ie. Fb@50 Hz. (gotcha?) Ok, then, aren't you losing the bottom part of the frequencies under 50 Hz?
Click to expand...

Greets!

OK, but they have one available, so no need to design/build one. Why do I want to control them? I mean the amp's interaction with them is what creates some BSC. The bottom end is filled in by the ML-horn gain.

GM
 
Inductor

Inductor

Member
Joined 2006
GM, I see you were here:
http://www.diyaudio.com/forums/showthread.php?threadid=51031

also checking about:
http://www.cognitivevent.com/av_he12.html
(...for people with guts)

I am looking at this two (coaxials):

Selenium Pro Coaxial 12co2p
don't look at the logo, they have the "no logo model" (SLF without the selenium logo print), and
don't look at the dips (freq. output) because it have the wrong xover.
http://www.seleniumloudspeakers.com/site2004/catalogo/pdf/pro_coaxial_12co2p_12co2p-slf_new.pdf

Eminence Beta 12CX
http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=290-504&ctab=2#Tabs
 
GM

GM

Member
Joined 2003
Inductor said:

Is that a quarter wave?
Click to expand...

Greets!

It's basically a linear expansion horn, so has a 1/4 WL fundamental with both odd and even harmonics rather than just the odd harmonics of a 1/4 WL pipe (TQWT or ML-TQWT) and why there's so much gain below Fs without the 1/4 WL pipe's HF excessive 'ripple' response.

GM
 
C

carcass

Member
Joined 2006
arqz.net
So, doing a quick comparison of 3 drivers...

[URL=http://img137.imageshack.us/my.php?image=compareps8.jpg]
An externally hosted image should be here but it was not working when we last tested it.


I get this... although beyma's impressive 30Hz it's SPL doesn't reach too far, am I right choosing another driver then?

Please excuse me for asking this kind of questions, but this DIY world is slowly starting to me.

ps. GM, about your ML-horn, would you be so kind to point me towards some enlightening article(s)/picture(s) about that type of enclosures.
Thanks in advance
 
GM

GM

Member
Joined 2003
Greets!

Not necessarily, it depends on many factors, some of which has been mentioned. For sure, if you want a simple rectangular box, then a driver with an Fs around the lowest frequency you want to audibly reproduce is required and ideally you'll want it to have a Qts around 0.35 for use with a SET. Once you move into ML-horns though, your driver options open up a bit.

http://www.quarter-wave.com/

Note that MJK refers to them as ML-TQWT, which actually refers to a reverse tapered pipe, while the ML-horn is a positive taper like his design: http://www.quarter-wave.com/Project02/Project_2_Front.jpg

GM
 
GM

GM

Member
Joined 2003
Greets!

From data given me by the local Altec rep and now archived here: http://www.wmeckle.com/ASHLEY/Ashley.htm

21.4 Hz Fs
1042.89 L (36.829313 ft^3) Vas
4.0 Qms
0.292 Qes
0.27213 Qts
12.54 ohms Re
817.2693 cm^2 (126.677"^2) Sd
32.26 cm (12.7") dia.
0.6 mm (0.1524") Xmax
2.5 mH Le
18.01 N/A BL (17.1351 calc'd)
38.6 g Mmd
50.847 g calc'd
1.124E-03 mm/N (1.0878E-03 calc'd)
2.57% ref. eff. (3.373 calc'd)

Note that calc'd values are off enough to make one or more of the measured ones highly suspect, but it's all I have and I was pleased with the results long before I knew how to check them mathmatically, so as always YMMV.

Hard to say, but in theory not much once you loosen up the suspension (assuming the spider is still pliable).

GM
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom