2235H Vent Sizing Assistance

[Chas]

I am about to embark on building a modular pseudo 434X system approach consisting of some components I have at present and hopefully will have in future. I am planning on having two 15" JBL woofers in two separate enclosures per channel with a third housing the MF/HF/UHF drivers that will fit in between. This hopefully, will allow me to experiment with MF and HF drivers and horns, two way versus three way, etc. without having to build new woofer boxes over and over again, since I am not all that adept at building cabinets.

So, the plan for now is to use finished Parts Express style subwoofer cabinets and merely cut the approprite openings as needed and stack'em.

To begin with I will use 2235H woofers in two 3 cu. ft. boxes per side. I know this volume is not optimal for the lowest F3, but these will be used in conjunction with subs, anyway. I would have preferred to use 2234H's but I haven't got any at the moment.

My question to you T/S software guys is: What would the best recommended FB and venting size and length arrangement for optimum transient response? I have ordered some 4" adjustable vents for starters, trouble is, I am not sure what to ultimately tune the box to. They will likely be crossed over to subs at 40-50 Hz.

Anybody have some thoughts or recommendations?

Charles.

[grumpy]

best transient response = minimize slope & look for low phase variation vs freq? ...
e.g., bessel-like response (I'm asking a question here).

If so, looks like ~4ft3 sealed, or if you stick with 3ft3 and opt for a natural rolloff to meet
your sub... tuning to low 20's with a single, long 4" port (24Hz -> ~17" long port). :dont-know
-grumpy

[Chas]

best transient response = minimize slope & look for low phase variation vs freq? ...
e.g., bessel-like response (I'm asking a question here).

Yeah, that's what I was thinking. I am striving for best upper bass articulation without resorting to the 2226 type of punch.

Subs are SUB1500 in sealed boxes, they're done and work great!

Thanks.

[Robh3606]

How much lower are the subs going to get you than a single 2235 in a 5.5 cubic ft box tuned to 30hz?? I would not use 2235's with a sub unless you are going to get some real low end into the sub 20Hz region or if you are an LFE nut.

You should be able to get a decent low end out of them without the added amps and crossovers.


Rob

[grumpy]

pulling the mass rings & re-doing the dust caps might help, if that's an option.

I did set up a SUB1500 + 4430 system awhile back, and while it may not go a lot lower
than the 4430 alone, what's there certainly becomes more obvious/present.
Granted, my living room is not "normal" and seems to benefit from bass
power that might be excessive in another room (or for someone with different preferences).

There are certainly forum recommendations for 1200FE units when/if available as well,
if shooting for something closer to current technology and "transparency"... whatever
that means .

You should be able to get a decent low end out of them without the added amps and crossovers.

I certainly agree it's been done (including as a sub).

[Earl K]

,,,,snip,,,,This hopefully, will allow me to experiment with MF and HF drivers and horns, two way versus three way, etc. without having to build new woofer boxes over and over again, since I am not all that adept at building cabinets.

- I can understand not wanting to build cabinets over & over .
- That said, ( IMHO ) 4.5 cu' boxes are more usefull ( even le14(s) are useable in this size. ) .

- I looked at a 2235 in a 3.5 cu' enclosure ( looks like another usefull size of box ) ;
(i) Sealed, it had quite a nice banana style curve / who knows if that's really desired in your room. F3 seems to be @ 55 hz .

(ii) Tuned to 35 hz , a lot of bass energy ( surprisingly so ) was recaptured under the sloping curve, giving an F3 of just under 40 hz ( assuming that today my flaky software is working correctly ).
- FWIW, MacSpeakerz suggests achieving this tuning with; (2) 4" diameter ducts that are about 13.7" long .

[Chas]

Thanks Rob, yes - I know it might sound crazy, but I am actually using two SUB1500's with my 4345's! Crossed at 40 Hz, they really work well in my room. Maybe it's my room, I dunno?

I figure I could use two 2235's in two separate boxes per channel and run them 40(or 50)Hz to 300 Hz or whatever range I need. Thing is, I'd like to have them optomized for the most linear, best articulation in these 3 cu ft. boxes. I am not too worried about F3, since the subs will take care of things in that department.

Maybe I should try them sealed first? Although a year or two ago I ran a 2235 in a sealed 5 cu ft. box (JBL 4505) and the F3 ended up around 50 Hz if I recall correctly. Seems kinda high....

If I could run around 35-40 Hz vented as Earl has suggested, maybe that would be a good solution.

Thanks everyone for chiming in, I'll let you know what happens as I progress.

[Chas]

pulling the mass rings & re-doing the dust caps might help, if that's an option.

I did set up a SUB1500 + 4430 system awhile back, and while it may not go a lot lower
than the 4430 alone, what's there certainly becomes more obvious/present.
Granted, my living room is not "normal" and seems to benefit from bass
power that might be excessive in another room (or for someone with different preferences).

There are certainly forum recommendations for 1200FE units when/if available as well,
if shooting for something closer to current technology and "transparency"... whatever
that means .



I certainly agree it's been done (including as a sub).

I am surprised you didn't get much of an improvement using SUB 1500's with your 4430's. Mine can rattle pictures on the wall at 18 Hz effortlessly....I rather doubt my 4430's could do that!

[grumpy]

I am surprised you didn't get much of an improvement using SUB 1500's with your 4430's.

Didn't actually say that ... I did say, "what's there certainly becomes more obvious/present". It will be interesting to see what you come up with, regardless.

[Chas]

Didn't actually say that ... I did say, "what's there certainly becomes more obvious/present". It will be interesting to see what you come up with, regardless.

Ah, okay, I understand now.

[Chas]

- I can understand not wanting to build cabinets over & over .
- That said, ( IMHO ) 4.5 cu' boxes are more usefull ( even le14(s) are useable in this size. ) .

- I looked at a 2235 in a 3.5 cu' enclosure ( looks like another usefull size of box ) ;
(i) Sealed, it had quite a nice banana style curve / who knows if that's really desired in your room. F3 seems to be @ 55 hz .

(ii) Tuned to 35 hz , a lot of bass energy ( surprisingly so ) was recaptured under the sloping curve, giving an F3 of just under 40 hz ( assuming that today my flaky software is working correctly ).
- FWIW, MacSpeakerz suggests achieving this tuning with; (2) 4" diameter ducts that are about 13.7" long .

Earl, the more I think about it, two 4" vents sound like the plan to start with and I will attempt getting them tuned to around 40 Hz. I always felt my 5 cu ft. sealed boxes were a bad idea with the 2235, it always sounded strangled to me.

Anyway, once this is up and running, I'll be able to have some fun (Zilch is my role model) trying out different ideas and JBL products in the third box.

First up will be 2123H/2421A/2307/2308/2405 in a traditional arrangement.