How should AJ-Horn be specified for BIB?

[freddi]

What is the proper input strategy for BIB type with AJ-Horn to get good simulation results?

[GM]

Greets!

Dunno, can it do linear expansion off-set driver horn? Or, a linear expansion vented that also allows a linear expansion vent be tacked on?

GM

[freddi]

hey GM - hows it going?

AJ allows driver offset down a BLH and also specification of a number of flares: parabolic, conical, exponential, hyperbolic, and a few more to get some ideas of what might happen. The expansion of whatever looks good can be saved as text file.

It looks to me BIB and others might not use ~Zero for their throat input alhtough the basic description in the manual seems to lean that way (?) results of a BIB looked waqy off whn I tried a small throat and moved the driver 0.69M down so I need descriptions of how to use this program and ideally half-space outdoors graphs of real loudspeaker.to see how compare.

There are AJ users but not seen the way they describe certain situations.

Cyburgs "Viech"

Armin Jost's input tor Cyburgs Viech rear loaded horn
http://www.aj-systems.de/sim/KT056_DasViech.gif

A simulation by me of 206E in Viech
http://img341.imageshack.us/img341/8...6viech1qz4.jpg

Comparison of Viech with 206E to RCA-Fan's littke hit box wtih 15"
http://img53.imageshack.us/img53/801...vsviechdc0.jpg

[Scottmoose]

Try giving the sim a small CSA for So. In MathCad, I tend to use the values GM advised: width of cabinet in inches x 0.125in, which works a treat.

Re the Viech, I thought it was an exponential flare rather than a conical (it's a while since I looked at it though, so I could well be wrong)?

Looking at the FR graph you've generated for it with the 206, and relating to what I've come across with BIBs, suggests that as is, it's too large -the dip between Fc and F3 is characteristic of an underdamped TQWT, and I doubt the different flare will change that a gread deal (though I could be way off there). Still, better too large a cabinet than too small, as I learned from GM -it just needs more damping.

[GM]

Greets!

My sinus infection is mostly dried up now, so much better! Just in time to spend the rest of this post-storm pretty afternoon cleaning up around the yard and drying out the workshop. At least my locale was spared any of the damage reported on the news. Anyway, hope yours is improving too.

I see Scott has clued you in on how to deal with the pointed end. What happens is the particles 'stack up' to create a finite area 'wall' to reflect off of. The flare should be half space linear (aka geometric?) rather than conic. Not sure which sim(s) you've compared, but for the 'standard' BIB, the length is 138" (3.5052 m) and driver down 30" (0.762 m).

Unfortunately, I've yet to see a half space BIB measurement, so not sure which program is most accurate, though it seems reasonable to me that however close the 'hit-box' is, so will be the BIB........

Please post the driver specs, cab dims you used to sim the 15" co-ax 'hit-box' and I'll post a MJK sim to compare.

GM

[freddi]

hey 'moose - whats "CSA"?

hey GM -

I'm not sure why Armin Jost specified Viech as conical (?)

here's the Eminence C15CX specs and dimensions for RCA-Fan's hitbox used in the sim above. There's ~70 liter rear chamber before the 0.9M long vent.

Hitbox dims
http://gallery.audioasylum.com/cgi/v...e=&w=628&h=583

M151 simulation in a different reflex vs real measurement with mic ~2M away and laying on the ground:


V-vent box simulation using RCA-Fan's imput - oops - botched throat area - should be 275 sq.cm. - probably didn't make a huge difference
http://img87.imageshack.us/img87/9868/sim151vkq6.jpg

ah - does make a difference - corrected throat area for V-vent with M151
http://img230.imageshack.us/img230/8788/betsimvyk1.jpg


V-vent box outdoors
http://img139.imageshack.us/img139/867/hawinv4ui.jpg

Eminence coax (- don't think specs are dead-on with my sample)

05-RE OHMS 6.39
13-FS HZ 56.80
06-LE MH .85
14-MMS GMS 53.10
07-QM 9.76
15-CMS mm/N .1479
08-QE .400
16-RMS NS/M 1.9423
09-QT .390
17-VAS LTRS 152.29
10-XMAX MM 2.90
18-SD SCM 856.34
11-BL TM 17.37
19-EBP 141.4
12-EFF % 6.70
20-SPL dB 100.3

[GM]

Greets!

CSA = cross sectional area (width x depth)

The expo expansion sim shown has a similar gain/broadband dip as AJhorn's and the difference using a conical or linear expansion just fractionally moved Fb around it's ~50 Hz Fb. The LF roll-off is much more gradual though, like your V-vent measurement. Apparently AJhorn doesn't sim the effects of summing the vent's output with the driver's above its mass corner, hence the lack of HF roll-off of MJK's model, so all things considered, MJK's seems the more accurate of the two.

GM

[freddi]

interesting - - I found RCA-Fan's curve outdoors for 2226 in the little hitbox


Simulation of hitbox (not dual v-vent box) with 2226 - I used Bill's input which is kinda cryptic for the vent's mouth - but can see it has little effect - he probably eyeballed the square root
http://img80.imageshack.us/img80/5662/hit2226simdz3.jpg

RCA-Fan's hitbox measured outdoors with 2226
http://img80.imageshack.us/img80/831...tcurvejyk9.jpg

oh - ps wonder what can be done on cheap to get listenable CD-based HE setup with solid-state amp? I use Samson but not thrilled with cd format

[GM]

Greets!

Good Q, the only Samson amps I'm familiar with are strictly sub duty SQ, so if still true, then there's no hope on wide BW combined with CD.........

GM

[freddi]

hi GM - FWIW used servo 260 and F1200 - weren't too bad although didn't have good reference - re:sub for those = 260 too weak, and 1200 can ratchet on bad loads which might work with old NAD (1200 fine with K and OB)

are there threads on getting semi-acceptable CD playback using consumer-grade solid-state amps/receivers?

Freddy