Box design for JBL 2205A

[acmv]

Hi,

Recently, just aquired a pair of JBL 2205A. Now, I want to build the enclosure for the drivers. Can some kind soul recommend to me some box designs? Thank You.

Looking at horn bass design, but I am open to suggestions. Thanks for the feedback.

[LE15-Thumper]

Hi,

Recently, just aquired a pair of JBL 2205A. Now, I want to build the enclosure for the drivers. Can some kind soul recommend to me some box designs? Thank You.

Looking at horn bass design, but I am open to suggestions. Thanks for the feedback.

Search the old library, you'll find plenty of options there.

[speakerdave]

Hi,

Recently, just aquired a pair of JBL 2205A. Now, I want to build the enclosure for the drivers. Can some kind soul recommend to me some box designs? Thank You.

Looking at horn bass design, but I am open to suggestions. Thanks for the feedback.

As I recall the 2205 was first an Alnico design (2205A/B) which, after the switchover to ferrite (2205H/J) because of external reasons, soon morphed into the 2225H/J with what changes I do not know. You might be able to deduce some of them by studying the T/S parameters. For rear-loaded horn the C34/4530 style enclosure would be OK for that driver.

Also, for bass reflex for hi fi use decide what kind of alignment you want and use one of the enclosure design software programs to get dimensions and porting details.

For SR use the JBL Pro Enclosure Guide will provide data. (GI)

[Ruediger]

The relevant Thiele Small parameters for the 2205A are:

fs = 30 Hz
Qt = 0.21
Vas = 297.3 liter

Qt will become a bit larger when a passive crossover is used. The combined resistance of amplifier, cables and the crossover’s series inductors determines Qt. See below for details.

Of the alignments in Thiele's tables only two are feasible with this driver.

No. 2, QB3, f3/fs = 2.28, f3/fb = 1.32, Cas/Cab = 7.48, Qt = 0.209
No. 3, QB3, f3/fs = 1.77, f3/fb = 1.25, Cas/Cab = 4.46, Qt = 0.259

There result the following boxes.

No. 2, f3 = 68.4 Hz, Vab = 39.7 liter
No. 3, f3 = 53.1 Hz, Vab = 66.7 liter

Any Qt with 0.209 <= Qt <= 0.259 is feasible, You need to do a non-linear interpolation between Alignments No. 2 and No. 3. For that You need Thiele’s tables. Somebody with a good design program could do that for You.

Alignment No. 3 will supply good midbass with punch Depending on Your taste You may need a sub then.

This post contains the "formula" how to calculate the resulting Qt.

http://audioheritage.org/vbulletin/s...&postcount=105

The data for the 2205A is:

Qa = 5
Qe = 0.22
Re = 5.5 Ohms

Ruediger

[acmv]

Thank You for the replies. But being an amature in speaker building, I am unable to understand the phrases used here. Things like Q values, alignment, etc.

So please pardon me. Is there any thing that I can read up, or maybe a few suggested designs that I can follow? Your effort will be most appreciated. Thank You.

[Ruediger]

Thank You for the replies. But being an amature in speaker building, I am unable to understand the phrases used here. Things like Q values, alignment, etc.

So please pardon me. Is there any thing that I can read up, or maybe a few suggested designs that I can follow? Your effort will be most appreciated. Thank You.

You can either build:

a rearloaded horn which will be 60 cm x 60 cm x 110 cm. Plans are readily available, for example JBL 4530. This will not supply really deep bass.

or:

a vented box, ca. 70 to 75 liters net volume. This will have a -3dB frequency of ca. 53 Hz. That is plenty of bass from a very small cabinet. For really deep bass You will need a subwoofer.

Make up Your mind, then we can proceed.

Ruediger

[speakerdave]

Use this enclosure guide: here's the link: http://www.jblpro.com/pub/manuals/enclgde.pdf

Here's the first page: Build #6.