2235 subs - standard ported alignment Vs EBS

[Doogster]

Hi chaps

I'm planning on building a pair of "subs" for hi-fi use, each using 2 x 2235 15 inch drivers. The word "subs" is a little misleading because I want to use them all the way up to around 500Hz when they will cross over to 2441s in large conical horns. I intend driving these subs with 500W power amps. Crossovers will be active tube devices I am currently homebrewing.

I've modelled the 2235 pairs in standard ported boxes using Boxplot and WinISD, and I figure I need approx 10 cu ft. That's with the tuning at about 30Hz. Response is nice and even, with rolloff starting at 40Hz. -3dB point is 34Hz.

An EBS alignment would require a much bigger box - 15 cu ft or bigger. However, I could then tune down to Fs, which is 20Hz. There is also an earlier rolloff, but the rolloff slope is very shallow.

My question is whether it is really worth it going with the EBS alignment. Is that extra 10Hz or so I'd be getting noticeable? What are the subjective differences between reflex and EBS? I like bass, but my listening preferences are jazz and classical - not exactly drum'n'bass!

Any thoughts appreciated. Many thanks. Doug

[paragon]

I will make a sim with this. Will take a few minutes ??

Eckhard

[paragon]

Simulation with two 2235 in a 400 L enclosure with a 21x20 cm duct 40cm long.

Eckhard

[Steve Gonzales]

Have you seen this?

http://www.lansingheritage.org/html/jbl/reference/technical/1983-subs.htm

[Chas]

Very intersting,
By EBS, I am assuming you mean active EQ? I haven't run the T/S numbers (due to lack of apprpriate S/W) but your 10 cuft data looks odd to me. I would think that the F3 ought to be around 28 Hz maybe even lower.

I am working on putting 2235's into boxes that are about 8 cuft. You're making me worry about whether or not I am making a good decision. Currently, the boxes house a pair of Altec 414z 12" and I can get (near field) to 28 Hz, no sweat.

[paragon]

The same with 225 L enclosure.

Eckhard

[Doogster]

Very intersting,
By EBS, I am assuming you mean active EQ? I haven't run the T/S numbers (due to lack of apprpriate S/W) but your 10 cuft data looks odd to me. I would think that the F3 ought to be around 28 Hz maybe even lower.

I am working on putting 2235's into boxes that are about 8 cuft. You're making me worry about whether or not I am making a good decision. Currently, the boxes house a pair of Altec 414z 12" and I can get (near field) to 28 Hz, no sweat.


Hi Chas

By EBS I mean making the box a lot larger than necessary, and tuning lower than usual. I do not intend using active EQ unless I need to.

Don't take my words too seriously - I am a strict newby when it comes to speaker design and construction.

I've only modelled my JBLs using WinISD and Boxplot (shareware), which apparently aren't the last word in accuracy.

Are you planning on pairs or single 2235s in that 8 cu ft box?

Cheers. Doug

[Chas]

I am using two per box and am intially using four 4" ID ports, 10" long per box as a starting point. My baffles are cut and I have all the hardware, I'm just waiting for JBL to ship my gaskets.:applaud:

[jbl]

Chas
Why not try (1) 2245 in that 8 cu.ft. box? Two 2235's will see 4 ft3 each.

Ron

[Doogster]

Have you seen this?

http://www.lansingheritage.org/html/jbl/reference/technical/1983-subs.htm

Yes I have, thanks. Doug

[Chas]

Quote: Chas
Why not try (1) 2245 in that 8 cu.ft. box? Two 2235's will see 4 ft3 each.

Ron

Only becuse 2235's are what I have. I am also planning to augment them with a pair of sub1500's in separate enclosures. Should be fun, six fifteens........!!!:banana: :dancin: :rockon2: :rockon1:

[Doogster]

Simulation with two 2235 in a 400 L enclosure with a 21x20 cm duct 40cm long.

Eckhard

Thanks for that Eckhard. I didn't realise it would roll off so much above around 100Hz. Perhaps I'll stick with the non-EBS model? Cheers. Doug

[paragon]

The roll of above 100 Hz maybe not correct. I will check this. Maybe i set the impedance of drivers to high.
Will post later.

Eckhard