Want to build a horn box for my JBLs (Pics!!!)

[Zac_cutt]

Hey guys, I have a set of L88s from 1974 in amazing condition.

I popped out the subs, and wow... Quality.

Anyways, I was thinking about building horn boxes for these.

Would it be reccommended?

I don't have the specs of these so its hard to figure out the design for it and size. Anyone got something you think would work for it?

BTW, the model of the sub itself is 123A-1 the model of the speaker, (sub, box, tweeter combo) is L88... Just to make it clear.

Zac

P.S. Here are pics:

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

 

[chops]

Those are 12" drivers, correct? I believe they were best in something like 2.5-3 cu.ft ported enclosures. That is if they were anything like my brother's old JBL L112's from the early '80s.

What would you want to build a horn for, for just woofer duty or subwoofer duty? I only ask because I'm not too sure if they do/can extend down low enough to do an acceptable job as subwoofers.

I could be wrong though.

 

[Zac_cutt]

Hmm, true, the L88s only came with sub and tweeter, next model up, L100 came with sub tweeter and mid.

That makes me think, do these play in between mid and base?

Anyways, yes, they are 12"... I just want to get as much bass out of them as possible.

Zac

 

[PSz.]

T/S parameters are here:
http://www.jblproservice.com/pdf/Thiele Small Parameters/Theile Parameters.pdf

regards,
PSz.

 

[Zac_cutt]

Thanks.

I have been trying to enter it into WinSD however I cant get it to work I am missing some info.

I am mainly missing:

Hc, Hg and Pe
CMS
Dd
RMS


Everything else is filled in fine.


Got any ideas?

This is the problem:

 

[Zac_cutt]

I then re-entered all data in the suggested order but was missing those details.

After trying it all It auto calculated all those details, except RMS.

Anyone see problems?

Thanks,
Zac

P.S. I tried 150 RMS which is what I think may be right and it displayed the same problem notice...

 

[Zac_cutt]

I found this:

http://manuals.harman.com/JBL/HOM/Owner's Manual/L88om.pdf

I basically got from it that "a quality amplifier delivering up to 75watts RMS per channel will provide optimum performance."

So I plugged in 75 RMS and still the same error message.

Edit:

Just found this:

http://www.jbl.com/home/products/product_detail.aspx?prod=L88&CheckProduct=Y

Does this mean the unit is 50 RMS?

Edit2:

Found this:

http://www.bassreflex.de/index/JBL/jbl.htm

Edit3:

http://audioheritage.csdco.com/vbulletin/showthread.php?t=4961

Zac

 

[chops]

BTW, it's not a subwoofer, just a regular woofer.

 

[xstephanx]

you coudl probably make it a horn loaded subwoofer though because its got a fiar bit of xmax and a qes>7, and the fs will be ok cause bass horns never have too low a cutoff.

 

[Rademakers]

Your Vas is wrong (way to big) and does influence other parameters as well, so does Sd 0,05 in^2 seems a bit small (SPL and No are totally off). Perhaps you should check the units used in the sheet and change them accordingly in WinISD.

Rms is a mechanical parameter, it isn't and has nothing to do with the (rms-)powerhandling. However Pe is the electrical Powerhandling (in Wrms).

Hc, Hg aren't necessary, they're used to calculate Xmax, Xlim can also stay blank.

With kind regards Johan

 

[Zac_cutt]

I got it to work!!!

Yes, it was a problem with the units, but its all working and looking more real.

Here is a pic of the specs. Tell me your thoughts.

How do I select a horn box in WinISD??

Zac

 

[Rademakers]

You don't because it can't. Use Hornresp instead.

With kind regards Johan

 

[Zac_cutt]

LOL... Why did I do that all then? Can I use the driver file I just made?

Zac

 

[Zac_cutt]

I entered as many feilds as possible but it was only like 18% out of all of them... My schematic shows:

Rear Com. Chamber = 14L
Conical Flare Horn Seg. 1 = 11.947L
Exponential Flare Horn Seg. 2 = 79.858L

Is this right?

I was orignally aiming to build something like this:

http://www.speakerplans.com/index.php?id=1850horn

Would I follow those plans exactly? I thought the size of the box had to fit the parameters of the sub?

Would putting it in a box like above be a reccommended idea?

Thanks,
Zac

 

[Rademakers]

LOL... Why did I do that all then?

I was asking myself a similar question

There is allot of information on how to build horns and how to work with Hornresp in the diy audio wiki. I would suggest reading it all and anything else you can find on the matter.

A horn is usually designed for a specific set of parameters, not just any driver you happen to have. That's why it might work, might fail. However there is an approach that has proven itself but it's input fields are all there for good reason.

We did the trouble explaining most in the wiki, it should give you a kickstart.

With kind regards Johan

 

[Zac_cutt]

Thanks for the help, I will look into it.

Now do I use Hornresp if I want to make a "folded" horn like in the link above a few posts?

Zac

 

[Zac_cutt]

How do I get to "hypexdesigner" from the tools menu? It doesnt appear.

Zac

 

[GM]

I entered as many feilds as possible but it was only like 18% out of all of them... My schematic shows:

Rear Com. Chamber = 14L
Conical Flare Horn Seg. 1 = 11.947L
Exponential Flare Horn Seg. 2 = 79.858L

Is this right?

I was orignally aiming to build something like this:

http://www.speakerplans.com/index.php?id=1850horn

Would I follow those plans exactly? I thought the size of the box had to fit the parameters of the sub?

Would putting it in a box like above be a reccommended idea?

Thanks,
Zac

Greets!

I don't use Hornresp, so don't have a clue, but if you read the 'suitable drivers' note on the dwg., it's clear that your driver won't work well in it.

Plugging the specs into Leach's math for a 54-200 Hz horn:

Vr = 608.727"^3
Vf = 39.845"^3
St = 13.769"^2
M = 1.05

The problem though is it has a high compression ratio (Sd/St) of ~5.516:1, way too high for a typical cone driver, so its power handling will probably be very low, especially since it has such a 'weak' motor that makes it much better suited to a large BLH.

GM