Similost's Speaker Build - Watch this space for lots of laughs.

similost · Jan 21, 2010

OK, I decided to get out of the econowave thread, and start my own thread, since basically this isn't an econowave build, but rather a strange experiment in trying to make good stuff sound like crap. I'm sure I'll succeed..

First off, the parts....

Starting out with a beautiful pair of Barzilay cabs... I'm sure I'll screw these up some how and the beautiful description will no longer be valid. Here's a picture so I can remember what they used to look like after I'm done trashing them.

I'll be installing that big ass Lambda driver in there... I haven't bought the shoehorn yet though...

OH yeah.. I forgot the horn.... It's a BMS 4555 driver, on a JBL 1.5" throated wave guide... I'll eventually get pictures of those in here too...

And just to confuse matters, I'll be installing a 15" passive radiator in the rear. Not a single person around here has attempted that for a waveguide build. SO, I might as well be the one to try it, and drive everyone crazy as I try to make it work....

I'll be building a pair of Zilch's modified M19 crossovers. This is the one part I really believe I'll be able to do without trashing too much.. Thankfully I do know how to use a soldering iron, and read simple schematics... but stay tuned for trouble shooting assistance I'm sure I'll need

OK... So I ran some box simulations... I'm about to post some graphs that mean almost absolutely nothing to me.. so if someone could help me understand what I'm seeing... I THINK I'm seeing good stuff.. but I really have no clue...

similost · Jan 21, 2010

OK, here's the box modeling I've done....

I really am not sure WHAT the PR15 is I have as far as the piston weight. I ran this simulation at 1400g, but I can weight the piston all the way up to 1800g if need be, BUT, I need to try and figure out how I can weight the piston portion? Any help with that would be a massive help...

So here's the numbers, and the resulting graphs.. ANY and ALL help appreciated... I don't really understnad what the peak I'm seeing is... Is that good or bad? What the hell is this thing tuned to? What kind of response curve do you think I'll see off this is? Will I make it down to 35hz? HELP!!!

similost · Jan 21, 2010

Here's the last two...

similost · Jan 21, 2010

I think I see a problem... appears I will be driving my woofer past it's max excursion if I pump the full 500w into them?

RayW · Jan 21, 2010

Yup. You've got the PR tuned way too low (12Hz or so ). It's not taking up any slack from the active driver. Start dropping the weight until you get things up higher and see what that does for your power handling.

similost · Jan 21, 2010

Thank you Ray... I was REALLY hoping you would step in here...

I was told that these drivers were originally set up to use in a box between 4 and 5 cuft... My box measures 4.5cuft, so I know I am within the range they were supposedly sold as a set to use with...

I'll change my numbers a little here, and see what I get... BTW, how do I know where I am tuning them to? I don't see where you are picking that 12hz up from? Give me a few, and I'll get you some new graphs.

similost · Jan 21, 2010

Here's the graphs with the piston weighted at 430g, the lowest they sell. I'm not sure if that is what I have or not. There are no markings on the drivers to give me a clue what weight they are, and the person I got them from has no idea either..

Forgot this one....

epifanatic · Jan 21, 2010

....looks interesting :music:

similost · Jan 21, 2010

I'm glad someone thinks so.. because to me, it looks like a train wreck already.. but I really have no clue what I'm doing with this box modeling and a passive.. SO, hopefully the pros will tell me what I'm doing wrong.. or if I'm lucky.. maybe right..

Rygen · Jan 21, 2010

Wow. Awesome project. Most of this is over my head, but watching with great interest.

similost · Jan 21, 2010

Yeah.. over my head too..

Just another thought here too... The 128 L size of the box will be dropping too because of bracing I'll be putting in, and I guess area lost for cones and horns too...

SPL db · Jan 21, 2010

epifanatic said:
....looks interesting

Is this seat taken?

RayW · Jan 21, 2010

similost said:
BTW, how do I know where I am tuning them to? I don't see where you are picking that 12hz up from? Give me a few, and I'll get you some new graphs.

When you look at the impedance plot of a PR (or vented) enclosure, there will be 2 peaks. The lowest point between them is the tuning frequency. In your first sim, the PR's resonance is below 10Hz so it doesn't show up on the plot, but the flat spot at the bottom is at about 12Hz.

Or you could take the easy way out. The numbers under "Passive Radiator Box" show Fb = 12.37Hz.

Your 2nd sim looks to be in the low 20's. Getting better.

Try around 300g for the passive and you'll get maximally flat with an f3 of 45, f6 of 39 (usually a good estimate of "usable bass") and it drops like a rock after that. You'll have good power handling up to about 300W and it'll give 123dB at 300.

At 500g you'll get an f3 that's a bit higher, an f6 that's a bit lower, and the bass won't drop off a cliff until about 30Hz. Your power handling comes down to the 220W range and your max output is down to 122dB.

I'd go somewhere in between those 2, personally.

similost · Jan 21, 2010

LOL.. I sure didn't see that...

So... I guess that if these drivers are at the very least they sell 430g, then the only way I could get them lighter is to start drilling lightly into the back of the masonite to lighten it more.

If I get it lighter, how would I know what the free air resonance is to input that. How can I also tell how much the piston weighs? Probably only by taking it out of the frame and weighing it? I sure don't want to do that..

So basically what I am trying to get at here.. is from what I am seeing even with the numbers I'm using, these drivers are very usable in this box? I just need to work on the tuning point...

marantzfan · Jan 21, 2010

Good luck with this build James, I'll be watching.

RayW · Jan 21, 2010

similost said:
So... I guess that if these drivers are at the very least they sell 430g, then the only way I could get them lighter is to start drilling lightly into the back of the masonite to lighten it more.

Actually, 430g looks like it would be a very good weight for your project.

If I get it lighter, how would I know what the free air resonance is to input that. How can I also tell how much the piston weighs? Probably only by taking it out of the frame and weighing it? I sure don't want to do that..

You cheat a little. You remove some weight and input the new weight into your sim program and it will update the Fs. Or at least every one that I've used will. The problem in your case would be keeping the sawdust to weigh.

So basically what I am trying to get at here.. is from what I am seeing even with the numbers I'm using, these drivers are very usable in this box? I just need to work on the tuning point...

Yup. I'd look at using the PR's stock.

You do know that the "M" on the TD15M is for "midrange", right? Those really aren't intended for subterranian bass. They'll rock from 40 or so up and they'll play way up into the mids where 15's usually don't venture but they're not subs.

Jailtime · Jan 21, 2010

This is gonna be fun!

What software do you use for box modeling?

similost · Jan 21, 2010

Thanks Ray. No I didn't know that the M stood for midrange. Now that's making me think I may have to get a pair of the S's and build me a sub box too... It will be interesting to see how these sound though... I wonder how they would compare sound wise to my C36's with the D123's in them.. or do those actually play lower than these will?

I've been using Unibox... Zilch turned me onto it... http://audio.claub.net/software/kougaard/ubmodel.html

Took me about 2 hours to figure out what the hell I was looking at, much less how to use it, but then I went to the web site and said DOH!!!!

spartanmanor · Jan 21, 2010

Looks like a good project James.

squirrelnest · Jan 21, 2010

When you get your speakers up and running........turn up the volume so I can hear them play from by house or at least feel the base!

Similost's Speaker Build - Watch this space for lots of laughs.

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