Mini DIY

[Zilch]

S'pose one wanted to make mini-4430 using 2404H-1. What would be the appropriate woofer to make a system that actually sounded good?

2118H wouldn't have extended bass.

Thinkin' Biradial Mini-Monitor here.... :)

[johnaec]

S'pose one wanted to make mini-4430 using 2404H-1. That thought was also going through my mind. I was thinking along the 115 series for LF...

John

[Zilch]

That thought was also going through my mind. I was thinking along the 115 series for LF....

Yup. 115H-1 looks right. Gotta look up the specs, now.

[Hee, hee....]

Giskard likes mini-monitors. He's probably tried this already.... :p

[mvaldes]

I bought a pair of 4312M last year during a business trip in Tokio
When I saw them I loved, but when finally I had hooked them at my home stereo I decided to keep them just as a "collector " item
Very nice to look, but not to listen.
Speakers are made in china and as stated by Anthony, very cheap.

But anyway, they look wonderfull

[johnaec]

Yup. 115H-1 looks right. Gotta look up the specs, now.Well, I did some relative measurements with the 2404 vs. the 2344, with a comparitive size of .4063. Scaling down a 4430 by that factor results in a cabinet that's smaller than L20T's, so they'd definitely be lacking in the low end. It'd still be fun, (and cute).

John

[Zilch]

That gets a 6" woofer, so we have that right.

Smaller than L20T, huh? That's PERFECT!

We'll make 'em deeper, if necessary. Nobody that doesn't have 'em knows how shallow 4430's actually are.... :p

L20T's crossed at 3 Khz. We're good to go! :thmbsup:

http://manuals.harman.com/JBL/HOM/Technical%20Sheet/L20t%20ts.pdf

I know where to get grille cloth. ;)

No compensation required for the tweeter, looks like:

http://audioheritage.org/vbulletin/showpost.php?p=60873&postcount=6

Tell us, please, Giskard, which crossovers to build for these.... :yes:

[johnaec]

L20T's crossed at 3 Khz. We're good to go! :thmbsup:We need to look at http://audioheritage.org/vbulletin/showthread.php?t=6368&highlight=ring+radiator+comparison #5, #6. It should be close enough for fun, maybe with a little HF padding...eve the 2404H-1 is good to at least 15K.

Edit: Sheesh - you beat me to it...

BTW - I think a moderator should move the last few posts to DIY - we've gotten kinda O.T. here...

John

[dancing-dave]

Well, I did some relative measurements with the 2404 vs. the 2344, with a comparitive size of .4063. Scaling down a 4430 by that factor results in a cabinet that's smaller than L20T's, so they'd definitely be lacking in the low end. It'd still be fun, (and cute).

John

Make it a 4435 so you can squeeze that extra LF from an added woofer.

I'm all about this :applaud:

[johnaec]

Prelim design: (mods - please move this mini 4430 stuff to DIY):

Edit: Thanks, mods!

[chad]

Was thinking of doing something quite similar :D .

Pair of 2404, 2118 crossed at 3k. Extended bass? Just an excuse to build another cabinet to use as a sub :).

[Zilch]

Prelim design:WAY cool, John!

Izzat cute or WHAT? :p

[Heh, heh.... :thmbsup:]

[dancing-dave]

To extend the LF do you think it would work to have this as a 3-way (in a 4435 configuration? Would it be too unorthodox to use a non-JBL woofer for this job? I don't want to be guilty of JBL-sin, but if the project is just about fun and getting the most from a small package, then it's the "feeling" that I think would be best to preserve.

Probably the best bump for the buck for the added bass in a 4435 configuration (6.5" high-excursion):
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=264-832

[johnaec]

Personally, I'm just sticking with JBL drivers - 'gotta have that "sound". ;) But by all means, anything is OK for fun.

John

[John W]

My Bel-Aire copies have been hooked up in the family room for about a month now, and I find them very listenable. These have 8 in 2110s matted with 2402 tweeters using a home built N2400 network. There is a subwoofer in the corner to fill in the low-end.
I have an extra pair of 2110s looking for a box, this looks like a great project for them. Does anyone have a pair of 2404s they are wanting to sell?:bouncy:

[Steve Gonzales]

My Bel-Aire copies have been hooked up in the family room for about a month now, and I find them very listenable. These have 8 in 2110s matted with 2402 tweeters using a home built N2400 network. There is a subwoofer in the corner to fill in the low-end.
I have an extra pair of 2110s looking for a box, this looks like a great project for them. Does anyone have a pair of 2404s they are wanting to sell?:bouncy: PM member Norealtalent, he can help.

[Robh3606]

That looks like fun!

Rob:)

[Zilch]

That looks like fun!Heh.

Rob's gonna cut some wood, sounds like.

[Time to dust off the Jasper Jig.... :thmbsup: ]

Anyone postin' pics of their Mini-4430's under construction here gets genuine JBL Monitor Blue grille cloth for them for free.

[Limited time offer; 2 sq.ft. max; good only while supply lasts.... :p ]

[pelly3s]

i thought of doing this a while back i just never got around to building it. or fixing the tweets that i have lol... the girlfriend keeps getting in the way of building things lol

[johnaec]

'Anyone have the width/height, (w/o base), measurements of the 4425? A"mini" would come out about the same size for the 4430 or 4425, (2404 doesn't change size :p ), but I'd like to see how the rest of the arrangement works out.

John

[Hamilton]

This looks interesting and fun, but....I'm wondering if they would end up being too similar to my 4206s to make it worth while? I've got brand new 2404s sittin' right here. :D

Zippy, what'cha think? And what'cha think about using the N4612B crossover?

http://www.jblpro.com/pages/recording/4200.htm

http://www.jblproservice.com/pdf/Cabaret%20Series/4612B.pdf

[Zilch]

Zippy, what'cha think?I'm bettin' Mini-4430's gonna be different from 4206, even if 4206 woofer (506G-2S) is used in lieu of 115H(-1). Widget, John, and I tested 2404 for polar response, and its power response is excellent:

http://audioheritage.org/vbulletin/showthread.php?p=60872&postcount=5

Compare to the other ring radiators immediatly above there.

I don't know how that compares to dome tweeters, but in your case, already having the 2404's, it'd be worth building up a pair just to find out. I'll be A/B-ing with 4401's I have.

If you find you like your 4206's better, another forum member will likely want your Mini-4430 boxes.

The crossovers are still undetermined. I'm hoping Giskard will have some suggestions. N4406 looks like a probable starting point. The final design will likely be biased and bypassed if the system warrants....

[John W]

'Anyone have the width/height, (w/o base), measurements of the 4425? A"mini" would come out about the same size for the 4430 or 4425, (2404 doesn't change size :p ), but I'd like to see how the rest of the arrangement works out.

John

Here is the tech sheet for the 4425:
http://www.jblproservice.com/pdf/Studio%20Monitor%20Series/4425LR.pdf
Its hard to read, but the dimensions are 16 x 25 x 12.26. The 2342 horn is 8.75 by 8.75, the 2214 is 12.25 in diameter, and the ports are 2.5 in

For an 8 in driver this scales alot nicer than the 4430. I think I will make mine .6 of a 4425, or about 9.5 x 15.375 x 8.5. This is a little deeper than the 4425, but I need the extra room.

[Zilch]

I think I will make mine .6 of a 4425, or about 9.5 x 15.375 x 8.5. This is a little deeper than the 4425, but I need the extra room.What 8" woofer would you use for Mini-4425?

[John W]

I have a pair of 2110s, which are the pro version of the D208. These are more full range than woofer, but I think I can get response down to 80-90hz which should be fine with a subwoofer.
I may look into replacing the aluminum dust caps with paper, one of them is a little dented anyway.

[kartsmart]

Any up dates on this neat little project. :p

[johnaec]

Any up dates on this neat little project. :pI'm hoping to clear a little space in the garage for using the tools. I hope to get some parts cut out next weekend...

John

[Zilch]

There's several of us seriously working on it, apparently.

I'm refining cabinet dimensions and scrounging up motors for my 2404 horns. :)

Gettin' the horns mounted at the top of the box per 4430 requires removing the "tire" from the 2404H magnet.

Maybe alnico 076 motors'd work, too.... :p

[johnaec]

OK - I modified the mini-4430 drawing somewhat, since without the tire on the 2404 they can be mounted much nearer the top edge. I also did a relative 4425. Since the 2342 horn is relatively smaller in the 4425 cabinet compared to the 2344 in the 4430, the resulting cabinet size is larger for the mini-4425, though this also equates to a better relative woofer match. I used JBL specs for scaling factors, even though the reality is slightly different:

John

[johnaec]

And because someone mentioned it, here's a mini-4435. Not nearly so cute, though... :p

John

[Robh3606]

I think the mini 4435 looks great!!

Rob:applaud:

[Zilch]

Hmmmm. What to build? :hmm:

I'm thinkin' the 4430's just too cute to pass up.... :yes:

[johnaec]

Hmmmm. What to build? :hmm: I've got a feeling we'll see all three... ;) The mini-4435 crossover might be a trick, though - (no 16 ohm 115H-1's). And I think it'd be really kool to have a little screwdriver adjust in front for at least the HF, ala factory...

John

[Zilch]

The mini-4435 crossover might be a trick, though....Naw, Rob's gonna work that one all out.

O.K., free grille cloth max is FOUR sq.ft. for anyone building Mini-4435, then.... :p

[Zilch]

Jus' need a coupla BOXES now.... ;)

[Ah-HEM!]

"Weed, whites, and wine,
And I'll be willin'...."

[That's one powerful little woofer. It shakes the bench, like WTPRO says....]

[Zilch]

Gonna use LE8T's for the Mini-4425's, probably, next project. :thmbsup:

Need some like 1/2" diameter slot-adjust knobs for the L-Pads.

Could make 'em, I guess, but if somebody can find a SOURCE, it'd help everybody buildin' these....

[johnaec]

Jus' need a coupla BOXES now.... ;)

[Ah-HEM!]

"Weed, whites, and wine,
And I'll be willin'...."

'Could use a little of that... :p Things got a little side-lined here, (out of state friend in town), and I ended up having to spend a bunch of time working on the office network today, ('have to go back again - :banghead: ), and band rehearsal tomorrow. :( I *really* am planning on getting on to them - I want a pair myself!

John

[Zilch]

I *really* am planning on getting on to them - I want a pair myself!Since these crossovers seem to work fine, I'll order up parts for a second pair, then.

I want to try a different LF inductor and layout using Solens and no bypass caps for comparison. Maybe set 'em up for passive biamp, too. Probably fit on the same 4" x 6" board.

Also gonna mirror-image the next set.

[Model "B". Heh.... :p ]

[John W]

I am glueing up my boxes now, I just need a crossover. Pictures tomorrow.
Zilch, what crossover are you using?
I switched woofers to the 506G and am thinking of basically a 4206 crossover with an added lpad.

[Zilch]

Hi, John.

These are N4406, an apparent good start. There's both a fixed and an adjustable L-Pad in the circuit, so they're easily tweaked to get the optimum balance. I looked at the comparable circuits, and this had the highest frequency.

I can't conclude anything or take decent measurements until the drivers are in boxes, of course, but they're good enough in bench testing I'm gonna build up a second pair for Johnaec....

[johnaec]

Zilch - I'm gonna' pick up some 1/2" birch on the way back from the office, (where I'm diligently working right now...;) ). The first sets I'm going to cut out are the mini 4425's - the drivers are much more accurately balanced size-wise than the 4430 combo. Is this OK with you? I plan on cutting out about 4 pair. I guess I could cut the mini-4430's out - it's just that I have to set everything up twice.

I also still have to assemble a drill press, (it's been in the box for months...), but you've really got me psyched up for this. I can probably squeeze around the saw, but it's still gonna' take me a few days...

John

[Zilch]

Sure, John. Either one is fine. We can recut the baffles on one pair for LE8T later, if desired.

The important thing is to get in some listening time with the requisite refreshing beverages.

[If I had a house guest, I know who'd be assemblin' the drill press while I was at work.... :p ]

[johnaec]

'Too late to get the wood tonight. I also realized we can use 5/8" - 3/4" thickness if desired, (but more expensive), since these won't have any free-standing front lip edges that would need to be thickness scaled.

We have four choices - 1) MDF, (need to veneer), 2) baltic birch, (need to veneer), 3) solid pine, (could likely be nicely finished with a dark walnut stain) or 4) real solid walnut, (??). I'm not real concerned about rigidity, the cabinets are so small and can still be braced if desired.

What do you think?

John

[Zilch]

:hmm: I'd say go with MDF for boxes, and birch for the front baffles, for extra strength there. That seems to be standard construction.

Whatever thickness is appropriate. We can rout out a little recess on the underside of the top for the 2404 magnet as required. JBL does that commonly....

[johnaec]

'Gonna see what's up with the wood on my way to band rehearsal today. 'Also just ordered an adjustable hole cutter for the drill press today - 'makes cutting these smaller holes much easier than setting up a router jig. 'Should be here in a couple days. And what with daylight savings time, maybe I can get some stuff done after work now.

'Any ideas on a good local source for some thin walnut veneer?

John

[Zilch]

'Any ideas on a good local source for some thin walnut veneer?Sure. MacBeath here in Berkeley:

http://www.macbeath.com/

[Look out for the elephant, tho.... :p ]

[John W]

Here are my 4425 minis mid-finish. The black fronts are just primed and I need to stain and oil the sides. They are built from 3/4 mdf with a wavy grained cherry venneer. I made a rabbet cut front and back to scale the sides like the original.
The parts for the crossover are on order.

[dancing-dave]

Here are my 4425 copies mid-finish. The black fronts are just primed and I need to stain and oil the sides. They are built from 3/4 mdf with a wavy grained cherry venneer. I made a rabbet cut front and back to scale the sides like the original.
The parts for the crossover are on order.

You are my hero.

[Robh3606]

Those look great!! Good selection on the woofer, that makes it look even more like a scaled down version. Can't Wait to hear how these mini's sound.

Rob:)

[Zilch]

SUPER, John W!

PM me your mailing address for your grille cloth for them.... :thmbsup:

[Zilch]

1) 2404H-1 #1 impedance
2) 2404H-1 #2 impedance
3) 115H-1 #1 impedance, Q/Fs
4) 115H-1 #2 impedance, Q/Fs
5) 4406 network impedance, unboxed drivers connected

[johnaec]

I found I have some 12-ply 5/8" baltic birch pieces in the garage - 'probably enough for 2 cabinets. What I'm thinking is that since these are so small, we can use mitre joints at the 4 outside edges, since those are the only important ones concerning clean seams. That way, the grain could be stained walnut, and eliminate the whole veneer thing. I think they'd look great, (the grain is nice), - what do you think?

John

[Zilch]

6) 4406 circuit simulation
7) Actual network voltage drive, 8-Ohm dummy loads
8) 2404H-1 performance on network RTA
9) 2404H-1 performance on network MLS

Approx. 10 - 12 dB additional HF attenuation required to balance....

[johnaec]

Here are my 4425 minis mid-finish.Way kool! Now I'm really getting excited! :bouncy:

John

[Zilch]

I found I have some 12-ply 5/8" baltic birch pieces in the garage - 'probably enough for 2 cabinets. What I'm thinking is that since these are so small, we can use mitre joints at the 4 outside edges, since those are the only important ones concerning clean seams. That way, the grain could be stained walnut, and eliminate the whole veneer thing. I think they'd look great, (the grain is nice), - what do you think?That'll work too, I betcha. :)

[John W]

What I'm thinking is that since these are so small, we can use mitre joints at the 4 outside edges, since those are the only important ones concerning clean seams.
This is basically the method I used. I veneered these prior to cutting the miters since the veneer was a little wavy and I wanted to make sure it was clamped tight.
One suggestion is to try and have lots of clamps on hand for the glue up. 4 front and 4 back on the corners.

[norealtalent]

You guys are amazing :thmbsup: Nice work! :yes:

[johnaec]

Zilch - I've calculated the internal dimensions of the L20T, (maybe I'll see what I can come up with for the 4406 also). Anyway, the L20T is 704.32 cu. in. gross inside volume. (I'll calculate the depth of the mini's based on this). I'm also roughly calculating the 2404 at about 30 cu. in. greater internal displacement than the 035Ti - I'll also compensate for this. The port is 1.875" inside dia, and 3.875" in length. Can this be broken down to two ports for the same 704 cu.in. volume, so that we might be able to fit them on the front? Otherwise, I think a single port will have to go on the back, like the L1's.

John

[Zilch]

Hi, John.

It seems to be tuned to 60 Hz. Two 1.5" ports 5.85" long (maybe less) will do the same job.

Now that I have the volume, I can play with the numbers a bit in BB6P.

I also want to see what can be achieved with heavy damping, which wants rear porting. PM me the final volume, please....

[johnaec]

PM me the final volume, please....?? I was just going to use the same volume, plus 30 cu. in. more for the extra space taken by the 2404 - so ~734 cu. in., (which would equate to the same 704 cu. in. with the 2404). I just need to calculate the depth to end up with that...

John

[Zilch]

Yup, that's what I'm using. Let me know if there's any "adjustments," is all, like from 4406 measurements....

[johnaec]

I actually calculate slightly less/equal volume for the 4406, so I suggest we just go with the 704 cu. in. of the L20T.

'Just waiting for the rain to stop so I can clean out some space and assemble the drill press. It's really too crowded for me to do without being able to shift stuff around outside while making room.

John

[Mr. Widget]

Hey when you guys are done please put together a picture thread of your Minis... most of us are only here for the pretty pictures.:applaud:


Widget

[Zilch]

Heh. We'll look forward to seein' your machined MDF curved-cabinet mini version there.... :D

[It's time you replaced your Brand-X rear surrounds with something neato DIY, anyway....]

[John W]

Here is the foilcal I plan on using.
I'm printing the image at 1/3 scale on the photo printer

[John W]

All done, but grills

[John W]

Here is the crossover I went with

[John W]

I started off with a 1mh coil for the woofer, but this caused more of a dip around the 3khz point, so I removed and uncoiled it down to about .8.
The Lpad is at about the -7db point. It might be a good idea to modify the fixed resistors to trim this a bit more.

Listening to the babies it is no surprise that they don't fill up the room with sound like their parents. But they sound quit good as a near field monitor.

[norealtalent]

SWEEEEEET!!!!:thmbsup: :thmbsup: :thmbsup:

[johnaec]

Way kool! What was the process for the foilcal once you printed it? Are you interested in printing a couple more? Zilch and I would likely be interested.

John

[mech986]

JohnW,

Your mini's are outstanding! A question on your 4425's - Are those also DIY units since there are no foilcals or level adustments?

Regards,

Bart

[John W]

I found a matte finish photo paper that seemed to work good. I printed it on the photo paper and once printed it was a little too dull. I then sprayed it a couple coats of clear lacquer and it came out about right.
I would be glad to work up a couple more if you would like. Just let me know the dimensions and if you would like any changes to the layout.

[John W]

The 4425 are copies too, built with info from the Quick and Dirty thread. Here is the original thread of these:
http://www.audioheritage.org/vbulletin/showthread.php?t=7110&highlight=DIY+4425

[Steve Gonzales]

Outstanding, as usual and as humble as you are talented, well done!!!

[Hamilton]

John, that is very nice.

[Zilch]

Oh, man, those are little BEAUTIES! :applaud:

[OLDGEN]

fro this time i am thinking that only in Japan can make minis:bouncy:
but now i have change my opinion:applaud:

[Zilch]

Testing 2nd generation biamp-able crossover with LE8T-H.

Solen caps, no bypass.

~12 dB fixed attenuation is required for 2404H-1.

It'll go into closed-box Mini-4425.

[I need a Mini-B380 to go with.... :) ]

[boputnam]

Not to go too far OT, but wrt Zilch's shot of the LE8T-H:

Zilch: I constructed a similar two-way with the LE20. It was interesting, but not sonically compelling. Anyway, those LE8T-H's look like the NOS that occaisionally appears on eBay - I had many. Check the surround join to the cone-edge - it seems with age (in the box) the surround was decrepitating and/or poorly glued, and separates easily from the cone-edge. Every single one I had needed to be resurround (since the spiders were unused they seemed in factory condition).

[Robh3606]

Hey Zilch if your are going to build a mini B380/go with a sorta half size 480 and use a 2214 as the 2245 substitute.

Rob:)

[duaneage]

I am amazed that these excellent projects came out of a photo in someone's office and a Japanese catalog of mini speakers for mini houses.

All we need now is a L250Ti mini project to top it off.

[Zilch]

Anyway, those LE8T-H's look like the NOS that occaisionally appears on eBay....Exactly, but these were purchased direct during the final production, "B" stock. One of the tinsels needs a bit more Moyen, but other than that, they're fine.

I've also tried an older pair of Alnico LE8T's with new surrounds, but find either, as you say, usable, but unexciting. CLIO has found some anomalies right smack in the 3 kHz crossover region, as well.

So, now I'm working with an old pair of 116A with new surrounds, which are doing nicely. Like 115A, they have a nasty peak, these at ~3480 Hz, but I've succeeded in notching that out (below). The performance is quite good, now, enough so to probably warrant hunting down some 116H-3's for more power handling and perhaps no peak to correct.

Other suggestions for 8" drivers welcome. :)

The 2404H-1's I'm using are of indeterminate provenance, and not performing as well as Johnaec's as measured by Widget. I have some new 2405 diaphragms to go in another pair of motors, which are on the way, so I'll soon be able to compare.

I don't believe JBL ever mated 2404H with a small woofer in a production two-way monitor, but it seems to work. There's a huge cost disparity, of course, in comparison to 035TiA and other dome tweeters they typically use, for example, but that's where DIY has an advantage; we don't have to give a whit about marketability.... :p


Hey Zilch if your are going to build a mini B380/go with a sorta half size 480 and use a 2214 as the 2245 substitute.Hmmm ... a Mini-B460. Now THERE's a project worthy of full-on pursuit! :applaud:

[jbl4ever]

How about the 4612 components with a 2118H

[Zilch]

and figure out what to do with the 4425 driver, horn and crossovers that I have

That one's easy - find another, of course.... :p

Or get a few more and build a 4435 mini....

Gotta love collaboration. ;)

Lessee: 8.75"/12.5" = 0.70

0.70 x 15" = 10.5"

So, pairs of anybody's favorite 10" or 12" woofers would make Midi-4435's using 2342 horns that'd potentially sound better'n merely good.... :thmbsup:

[Zilch]

Johnaec did the cabs,
I did the crossovers,
and JBL did the drivers.

[Still gotta find some more knobs.... ;) ]

Heh.

[John W]

Those are great Zilch. I like the proportions of a little larger woofer.
What is the woofer, and are they sealed or is there a port in the back?

[Zilch]

Hi, John,

They're 116A's, and the boxes are sealed.

(Prototype response curve above.)

Still looking for other 8" options to try.

As jbl4ever suggests, 2118H would work, but they'd almost certainly require a sub.

I can add a rear port at any time for others, if required.... :thmbsup:

[Should I put mini-spikes on 'em? ;) ]

[Zilch]

O.K., where's the pic of the transparent red L250's from down under?

That's how I wanna finish these.... :yes:

[Zilch]

All right, I ain't tellin' how they sound then.


:baby:

[Real 2404H's (not H-1's) running in them now.... :thmbsup:]

[Zilch]

1) Parts Express #091-1247 input terminals are staked through 3/8" thick hardboard then mounted from inside on the rear baffle. Recessed 3/4", they end up flush.

2) Crossover board then mounts on 1/2" standoffs with input terminals running through (upper right) making a direct connection.

3) A layer of R-13 on top adds up to ~50% fill. Still determining what's optimum damping for these.

4) Nearfield low frequency response, L & R. I don't know what's happening at 2 kHz there; not part of the design, for sure. It doesn't appear in the midfield response, next.

5) Full system response, both sides playing, mic at acoustic center ~2 M from each. I play the orange HF response mostly.

Note smoother and more extend VHF response of 2405 diaphragms in comparison to "H-1" with 2402 in post #81, above.

So, is it possible to make "listenable" minis?

Absolutamundo.... :thmbsup:

[johnaec]

'Looks good, Zlch! (I see you found some knobs. :) ) Now, a little stain, the foilcals, and some grilles.....

John

[johnaec]

I finally got to listen to Zilch's mini-4425's today, (mine are still in the construction phase), and have to admit - they sound pretty good! While bass is somewhat rolled off at the very low end, they're surprisingly smooth sounding speakers. Hopefully, mine will be together soon, and we can see how ported 115H-1's sound compared to Zilch's sealed 8 inchers... The high end is definitely really nice and smooth. :)

John

[Zilch]

BB6P says I should be doing better at the low end than I am, with usable bass down to 36 Hz. I'm up around 45 to 50 Hz right now, according to the nearfield measurements (above).

It's difficult to find 116's (A or H) with ACTUAL Fs = 28 Hz, as many have been refoamed, and I suspect the spiders are now stiff, too. Looks like recone's the only good answer.

Audivex is helpin' me with that. :bouncy:

[Still gotta tweak the box damping, apparently, too.]

In the meantime, they're mighty pleasurable listening.... :thmbsup:

See Dickason's LDC6 Studio Monitor project in Loudspeaker Design Cookbook for more on the closed-box design approach to Minis.

[johnaec]

I've been working on putting my 4425 mini's together this weekend, but remembered I had some pics of putting Zilchs' cabinets together.

I cut out parts for 5 cabinets, (1 spare just in case). These were made from 3/4" birch ply, with full mitered corners and rabbeted fronts and backs. But after the hassles of dealing with cutting and gluing up clean miter joints, I'm going to the nail gun and veneer from now on. :o:

The first pic shows the parts for 2 cabinets, including the extra pieces for adding the additional baffle depth behind the horns.

The second pic shows the clamps required - I used even more on the next cabinet!

3rd pic shows the raw cabs, front and inside, before mounting and trimming the extra horn baffle.

4th pic shows the completed cabinets, (backs removed), ready for staining and components. Zilch has already posted pics with his components installed, and JohnW was kind enough to provide us with really nice foilcals for the finishing touch!

I think I'm going to leave my pair in plain birch finish, with a clearcoat. Using the JBL bule grillecloth, I think they'll look pretty modern/contemporary. :) I'll be trying both 115H-1's and 706G-1's, (as in L1's, etc.). The 706G-1 actually looks to have a slightly larger magnet.

I'll post pics when I finish mine, but I'm sure it'll be at least another week. It's 113 degrees in my yard today, and 90 inside - 'way too hot to do much work - I can barely sit here and type... :flamer:

John

[Zilch]

There was a recent post in these forums regarding design of Project Array discussing that the slot orientation was selected based on the fact that pattern control and smoothness in biradial horns was not as good from the diffraction component as from the radial, and since horizontal dispersion was more important than vertical, the slot should be oriented accordingly, i.e., sideways.

That tells me that the optimum orientation should be as shown below, yet in Project Array, the slot is oriented "in the vertical plane," according to the text descriptions. I can't see it (the slot) in any of the photos. Can someone link to the post I'm referring to, please? I cannot find it now, of course.... :banghead:

The 2404H spec sheet seems to indicate that this "hourglass" orientation is, indeed, better. I THINK the beamwidth chart shows vertical is flatter above 5 kHz, tho I can't quite read which is which there:

http://www.jblpro.com/pages/pub/components/2404.pdf

The off-axis response drops off more quickly beyond 45° in the vertical, which would reduce (attenuate) sidewall reflections when the horn is rotated 90 degrees, and would seem to be the better orientation so long as the floor is not reflective.

No? :confused:

[Earl K]

Zilch ;


There was a recent post in these forums regarding design of Project Array discussing that the slot orientation was selected based on the fact that pattern control and smoothness in biradial horns was not as good from the diffraction component as from the radial, and since horizontal dispersion was more important than vertical, the slot should be oriented accordingly, i.e., sideways.

That tells me that the optimum orientation should be as shown below, yet in Project Array, the slot is oriented "in the vertical plane," according to the text descriptions. I can't see it (the slot) in any of the photos. Can someone link to the post I'm referring to, please? I cannot find it now, of course....

- I'm pretty sure that somewhere you've misinterpreted G.Ts' words ( plus I believe you may be mixing planar horn surfaces ( conical ) into your thinking .

- I've always found that the 2344 measures better in the horizontal axis ( with vertical slot ). For instance ; 16Khz does a great job diffracting past that fairly sharp edged vertical slot .

- Don't know the referenced thread offhand / though , I may look it up for you / use your CLIO to settle the question .

:)

BTW ; cute little speakers you guys are making / very nice . :applaud:

[Zilch]

BTW ; cute little speakers you guys are making / very nice . :applaud:Thanks, Earl. :thmbsup:

Would only you could hear their ground-shaking bass and window-shattering highs!!!

[Heh, heh.... :D ]

[Zilch]

LE8T-H gets a final old college try. Kinda dull, clinical-sounding, like music appreciation class. Usable bass (-10 dB) only down to 48.6 Hz. They want plainsong played through them, not R&R.

Minis should be "ballsy," I think. 116H-1 (pic in #94, above,) certainly gives them that in these small closed boxes. Qtc is downright embarassing. [Think L100.... :p ]

Also tried perf-frame HTI8 woofers with butyl surrounds and coated aluminum cones. They're fine, but the stamping is made for rear mounting which also seals to the surrounds. I'd have to devise some custom rings and clamps to install them confidently from the front. Nearfield LF response reveals them as a compromise between LE8T-H and 116H-1.

HTI8 crossover (bottom, left) is symmetrical 18 dB/octave at 2.5 kHz and works well. Ordered parts to build up a pair with better caps and coils. It buries 116H-1 response anomaly at 3.5 kHz; no supplemental notch filter required. :thmbsup:

Same circuit as Control 128W here: http://www.jblproservice.com/pdf/Control%20Contractors%20In-Wall%20Speakers/Control%20128W.pdf

I'll post the revised schematic and parts list with tweaked Zobel and 2404H(-1) attenuation after testing my DIY version. Maybe I charge-couple the HF, too.... :hmm:

[4313B]

Gulliver's engines (http://www.machinedesign.com/ASP/viewSelectedArticle.asp?strArticleId=60688&strSite=MDSite&Screen=CURRENTISSUE&CatID=3)

[Zilch]

Way COOL, Giskard!! :thmbsup:

[Hamilton]

Man, that Knucklehead sounds better than my Twin-Cam. :( :D

[Zilch]

Re: My post #94, above, here's the citation:

http://audioheritage.org/vbulletin/showpost.php?p=108972&postcount=12

[Lemme read it again. :p ]

O.K., I'm still confused by this. K2 slot is horizontal. Diffraction controls the vertical dispersion like in Smith horn, no? This would be optimal.

Whereas, in 4430's 2344(A), the slot is vertical, and the diffraction controls the horizontal dispersion, i.e., not optimal, according to the theory.

I'm also thinking about PH-316 studies (also vertical slot,) where rotating the horn 90° gives better (more controlled) horizontal polar response.

"What Greg Timbers discovered is that the diffraction slot is more effective in maintaining uniform polar and amplitude response in the vertical plane than the compound geometry is in maintaining uniform response in the horizontal plane."

That's with a horizontal slot, then? The straight edges of the slot are doing (controlling) the dispersion? :dont-know

[spkrman57]

Man, that Knucklehead sounds better than my Twin-Cam. :( :D

Wonder how much it would cost for one of them motors???

Ron

PS: sorry for OT!

[4313B]

Wonder how much it would cost for one of them motors???Alot - http://www.replicaengines.com/


PS: sorry for OT!Yeah, Zilch's photo of the LE8 reminded me of how many of them I killed running them in the rear decks of various daily drivers back in the 70's.

[spkrman57]

Neat as hell though!

Ron

[Zilch]

18 dB/octave factory HTI 8 crossover, left.

Biased HF DIY version, right.

Circuit sim voltage drive, bottom.

Maybe Earl'l tell us what's going on there.

Kinda silly puttin' all this effort into Minis.

['Til ya hear 'em.... :D ]

[johnaec]

Mine are finally all trimmed down, (for some reason, yours were much easier, Zilch - I think my pieces may have warped a little bit sitting around so long waiting for assembly). They're now ready for black paint on the fronts, finishing, and filling out. 'Coming soon...

John

[Zilch]

Well, you're gonna hafta go into production on cabs, John, 'cause I have two spare sets of woofers, tweeters, and crossovers, and plenty friends and relatives wantin' their own "Minis" now.

[I COULD rework these AR4xs, I guess, but they're not mirror-imaged, and they lack Mini-panache.... :p ]

[Zilch]

Comparison of nearfield LF response of the two crossover topologies.

HTI-8 18 dB/octave filter buries the 3.5 kHz peak -30 dB. :thmbsup:

So much for L100 midrange voicing, tho. :hmm:

Well, maybe there's a wee bit left -- still got the midbass bump.... :p

AutoEQ says I'm 4 dB too "hot" at 800 - 1 kHz, bottom.

Zobel tweaking time, maybe.

[Purty close, tho, +/- 2.5 dB overall. Normally, I'd quit, but I can hear the difference on these.... ;) ]

[Earl K]

Hi Zilch


HTI-8 18 dB/octave filter buries the 3.5 kHz peak -30 dB.

- I haven't been paying close enough attention I guess / but what is a HTI-8 network ? & where is the schematic ?


Maybe Earl'l tell us what's going on there.

- I'm lost in the ozone here / hard to offer any insights , since I don't even know the topic . :D

- The above curve looks " nice " . Where did the 3K peak go ? ( Or was that the question that I was supposed to guess an answer to ? )

- Anywho,,, as the AM series of networks clearly indicate / one can use a series LCR ( strapped in parallel ) after the main LC elements. In that position ( posterior position ) , one will get the expected "notching" . The "R" value is dictated by 2 things; the impedance one finds in that part of the circuit ( I call it the "loop" impedance / it needs to be measured or calculated ) and the amount of desired attenuation. Using the simplified db 20 Log formula for impedances ( which you gave me ) / one can get a good ballpark "R" figure to start tweaking with ( or one can guess at it easily enough ) .


:blah:

[Zilch]

- I haven't been paying close enough attention I guess / but what is a HTI-8 network ? & where is the schematic ?Heya, Earl. :D

HTI-8 is an 8" woofed JBL Consumer in-wall (i.e., closed box) home theater speaker. The similar Pro version is Control 128W, which uses the same crossover network, but has slightly different woofer parameters. I linked to the schematic here:

http://audioheritage.org/vbulletin/showthread.php?p=115420&postcount=97,

and built up a pair to install at #105.

It looks like standard three-pole plus LF Zobel topology to me; I was hoping you could offer insight as to the humps and dips both sides of the 2.5 kHz crossover frequency there: Chebychev?

In any case, in switching to 2.5 kHz crossover point from 3 kHz and using steeper slopes, this buries the 3.5 kHz bump in 116(H-1) response effectively without a notch filter, so I'm now looking at what additional tweaking to consider. It's playing about 4 dB too hot at 800 Hz - 1 kHz. See GEQ curve after AutoEQ, above.

I've got the fixed HF padding dialed in pretty well, looks like. There's just 1.5 dB excess with the adjustable pad full on, leaving a little headroom for an absorbent listening space. I may give it just a bit more.

*****

Jeez, these sound good. :thmbsup:

I'm playing them with LE14H-3 subs right now....

*****

Edit: Zobel tweak'll do it, looks like (blue). Just hafta make an "empirical" determination of the optimum values, now.

[Wearin' out the T-nuts on these little boxes tryin' all this stuff.... :bouncy: ]

[Earl K]

Hiya,


It looks like standard topology to me; I was hoping you could offer insight as to the humps and dips both sides of the 2.5 kHz crossover frequency there: Chebychev?

- Oh,,, the peaking . Anytime I see that, I assume the filters' poles have come closer together than what a typical Butterworth transform calls for .
- IOTW ; a bump filter has been created.
- In a 2-pole setup , one can't bring the poles closer together than an octave spacing before peaking/resonance/gain starts to occur.
- ( Bessel = 1.5 octaves / LR = 2 octaves in pole spacing ).
- I had wanted to talk about this in my thread called "Bump Filters" ( or something like that ) but it didn't go anywhere. All the old stuff that uses 2307 horns have significant "Bump Filters" in them / artificially supporting the lower end response of those weenie horns ( or so say my calcs. ) . This does have relevance to you guys wanting to "squeak" out a bit more lower end response from those PT wavequides ( even the 2344/4430 "cheated" a bit in this regard ) .

- I've got to go now , it's BBQ season . :D :)

[johnaec]

OK - first little teaser stuff. Cabinet fronts are finally painted, but I still haven't decided whether to stain the cabinets or leave them natural for that "modern" look. They'll have JBL Blue grilles either way.

I'm going to try the 6.5" 706G-1 LF speakers from the L1 series first. I attached a couple pics showing the difference between these and the 115H-1's, which are my other option. As seen in the pics, the 706G-1 has a ribbed paper cone, and its magnet is also about 1/8" deeper than the 115H-1, (magnet diameters are the same). Both speakers use the same mounting and bolt holes.

The last pic shows one of the cabinets with only the drivers mounted, (excuse the dust!). I still need to mount the crossovers and binding posts Zilch provided, install the port tubes, attach the foilcals provided by JohnW, and assemble and mount the grilles, (and decide on the finish).

I'm going on vacation starting next Thursday for about a week and won't get anything more done on them before I return - 'too much other stuff I need to do before leaving. 'Just wanted to provide an update.

John

[Zilch]

OK - first little teaser stuff. Way COOL, John!!

[Minis are proliferating.... :thmbsup:]

[Zilch]

Top:

1) Nearfield LF response before tweaking (red).
2) Zobel compnents adjusted per sim, above (green). It did just what the Spice sim said, between 400 Hz and 2 kHz.
3) Full range response afterward (violet).
4) For those thinking to use 2118 (orange) before tweaking, but it's a "J" so ignore the low pass response at the high end there.

Second:

1) Full range RTA response 4 Pi freefield (violet).
2) Same, 2 Pi, about 4" from wall (white).

So, useable bass response (-10 dB) is good to ~25 Hz.



Remaining 3.5 kHz peak is apparent, but it's clearly not (much) coming from the woofer anymore. :dont-know

[I'll see what AutoEQ says after installing the mods in the second speaker....]

Edit:

Third: AutoEQ result after adjusting the Zobel on both. Now +/- 2 dB. It sees the remaining HF peak as 3 dB between 3150 Hz and 4 kHz.

Bottom: RTA with AutoEQ (red) and with no EQ (orange), raised 10 dB.

I'm about to invoke the DIY Credo on these: [I]"Hey, that sounds good enough to me. My system is done dude!"

[Just 'til I figure what else to try, of course....:p ]

[Zilch]

My 8" woofer, closed-box Minis went to Mr. Widget's for an audition today. Results, playing freespace:

1) Major points for cuteness.

2) Bass has good tonality.

3) A midrange peak.

4) 2404H tweeter is a bit harsh.

Overall: Fun.... :thmbsup:

[Mr. Widget]

My 8" woofer, closed-box Minis went to Mr. Widget's...Zilch had asked me to comment, but I was AWAL earning a living... or attempting same.

We put the little Mini's on makeshift stands next to a pair of stand mounted mini-monitors that I use in my "upstairs" system. We fired them up and it was surprising how tuneful the bass was. I doubt it would satisfy any fans of organ music or contemporary electronic music, but for "normal" music the low end sounded flushed out, had a nice snap to it, and sounded "right".

I thought the mids were a bit harsh and in your face. They were also not terribly revealing or detailed... more or less what you would expect using a doped cone 8" woofer up to 2-3KHz.

I have never been a fan of the 2404 and sure enough the VHF was missing, there was a lack of a sense or air or space, and what was there was a bit hard and abrasive. Comparing it to an aluminum domed direct radiator tweeter in my mini-monitors, even the designer commented on the harshness. :)

Since "cute" is the primary design goal, the option of changing the tweeter which could remedy most of the system's sonic short comings isn't an option. It'll be nice to see them in walnut with some JBL blue grilles.


Widget

[Zilch]

Thanks for your review, Widget! :thmbsup:

I'll work more on the mids; Audivex gave me some suggestions today.

But we're SOL on the tweeter 'til I find a small Ti dome or re-entrant Mylar to mate with the 2404 horns. :p

[Zilch]

O.K., fixed the midrange hump per Audivex suggestion:

1) Untweak the Zobel

2) Add notch filter

Tried parallel notch first, but additional inductor impedance in series with the woofer pulled down the entire midbass response. Sounded like L100. Kinda nice, actually, but puts the woofer more at risk.

Series notch (in parallel with the woofer) levels out the response (blue). Zobel's gotta stay, looks like.

See post #110, above. Same game; bigger and lower than what I could achieve tweaking the Zobel, is all.... ;)

[Zilch]

Johnaec provided an additional closed Mini box for testing of 8" woofers. Kinda backwards working with a fixed box size, but that's the project.

Here's the nearfield LF response of the variety I have tried here:

1) 116As and 708G-1s (Org, Lt. Grn)

2) 116H-1s (Red, Grn, Gry,) LE8s (Blu, Vio,) and LE8T-Hs

3) D216s, 2118J, Control 128W and HTI8

Face-mount D216s were, uhmm, problematic. ;)

The in-box numbers (measured with WT2) tell the tale:



Fc, Qtc116A = 71.51 Hz, 1.03
116H-1 = 74.28 Hz, 0.94
708G = 69.26 Hz, 0.84
LE8T-H = 82.20 Hz, 0.95
LE8 = 85.77 Hz, 0.90
D216 = 110.33 Hz, 0.57
2118 = 111.23 Hz, 0.70
128W = 73.79 Hz, 0.82
HTI8 = 72.51 Hz, 1.00

I am reporting the measured Fs and Qts of the woofers mounted in the box as Fc and Qtc here. It takes less than 5 minutes to do the measurement on each using WT2. :thmbsup:

Dickason characterizes Qs in the vicinity of 1 as having "a warm, if somewhat robust, quality that audio marketing people describe as 'saleable.'"

"Lower Q values around 0.8 sound more detailed (due in part to improved transients) and, by comparison, somewhat shallow. Qtc = 0.5 is usually regarded as excessively taut and overdamped. Some authorities, however, still consider this value (0.5 - 0.6) to be optimal."

Use 708G-1 or 128W for the somewhat flatter bass response of Qtc just above 0.8. LE8(T), too, but they don't play as low, by ~10 Hz. See the first set of curves comparing 708G-1 vs. 116A for the difference between Qtc 0.8 and 1.0 presented graphically. Yes, the 116A's 2 dB "hump" at 100 Hz. in this alignment matters, and yes, the difference in bass response is really, really audible. Think L100.

My personal main pair are currently running 116As with the notch filter posted above to tame the mids (400 Hz - 1.2 kHz) a bit. They've got good extended bass with 2 Pi boundary reinforcement; no sub required. Note that these have the highest Qtc of all those tested. Minis should play "Big," I say. :p

Zilch's DIY 8" closed-box mini builder recommendation (bottom): HTI8 with rubber-surround polymer-coated aluminum cone, available lately in pairs from Harman on eBay for under $100 including crossovers ($549 on their website, $579 list.) L-pad down the HF ~12 dB for 2404H(-1). You get two bonus Ti Lam Dome tweeters (Made in China,) and plastic in-wall frames to play with. :)

Harman lists them with a space before the "8", so search for "HTI 8". There's typically two one-day auctions running continuously. Check completed auctions to see what they've been going for....

[Note: HTI8 requires a slightly larger than JBL standard baffle cutout, and mounting bolt locations are different as well. Pay particular attention to achieving a good seal to the limited available flange area between screws without warping the stamped frame; Parts Express #269-300 sealing caulk will do it.]

[Zilch]

May be hard to find HTI8 in all of that, so here it is separately:

1) MLS nearfield response of two HTI8 woofers, blue and light blue. Unit #2 on JBL factory HTI8 filter, red. Midfield response at 1M, grey and orange. Filter knocks the 5 kHz peak down 30 dB.

2) Same midfield on filter, but measured sinusoidal instead of MLS. Could use a notch between 400 Hz and 1 kHz, a familiar tweak from above.

3) RTA of full system response with 2 Pi boundary reinforcement. Less boomy than 116A version, but still good down to 35 Hz and below.

[Not that I mind Mini boom, of course.... :p ]

Edit:

4) With notch filter, nearfield (red) and midfield (orchid).

Peak at 300 Hz is today's room thing, looks like.

[What Zilch did today.... :) ]

[Zilch]

JBL SP8 titanium laminate woofers, cheaper than HTI8, even.

Why these models? They're from "In-wall" products, i.e., closed-box; EBP 65 and 66, respectively.

Yup, these work too, 4406B Xover, 3 kHz, but it took two notch filters to tame them, left.

[LOOK cool, tho.... ;) ]

[johnaec]

...but it took two notch filters to tame them, left.'Obviously caused by the "mini-port" below the horn with wires coming out of it... :p

John

[Zilch]

HEY!! :hmm:

It's about time we got YOUR Minis down here for measurement and test, John. ;)

[AND, about 5 more cabinets, so's we can A/B/C/D/E/F/G them.... :p ]

[demon]

hey!

great old thread i found here... i really like that idea -because i got the same a few months ago. but i was also thinking about the big theater 4675 (http://www.jblpro.com/catalog/General/Product.aspx?PId=77&MId=1)http://www2.jblpro.com/BackOffice/ProductPicturesSmall/80ec668a-390a-4425-b6a4-db7a51816fa2.jpg wich could have been a really really really tiny desktop machine. proportional and acoustically fitting "15"bass" might have been troublesome though...

anyway: late congrats on those 4425 minis!! they look fun!
any updates since last post here?

cheers,
mikey

[Zilch]

anyway: late congrats on those 4425 minis!! they look fun!
any updates since last post here?No, but regarding the woofers, I reverted to 116H.

Johnaec also built a nice pair (he made the cabinets for both of us,) which may be available for purchase here on LHF.... :mad:

[soundmotor]

For later reference.