Yet another 4425 DIY

[jerv]

I'm in the process of building a 4425 DIY. Just for the fun of it, I plan to design new crossover networks in addition to replicating the originals. Maybe the difference (?) could provide some insight and learning experience.

However, somehow I seen to have gotten into some momentarily trouble with my soundcard/measuring gear, and need some verifying. Does anyone have impedance plots (or even better: impedance files) for the 2214H and the 2416H on 2344 horn?

Thanks, Espen

[Don Mascali]

Look here:
http://www.audioheritage.org/vbullet...highlight=2342

The L200t3 is nice. There is alot of info from the Zilch project cronicled
in the "Quick and Dirty" thread. He tested that horn amongst many others. There are many strategies for dealing with CD horns in the X-over topologies shown in that thread and many other places here.

The search fucntion is your friend. You could spend weeks reading up on this stuff.

Good hunting,

Don M

[Zilch]

Does anyone have impedance plots (or even better: impedance files) for the 2214H and the 2416H on 2344 horn?

I believe you mean 2342 horn, which is thread-on and accepts 2416H. The larger 2344 is bolt-on, and NLA.

Here's the roadmap for Q&D:

http://audioheritage.org/vbulletin/s...ead.php?t=9901

[Don Mascali]

The 2344 has about a 12.25" square mounting area where the 2342 is 8.75". JBL used 1000 HZ on 2344 and 1200 HZ on the 2342 as the nominal X-overs. Both have the infamous butt profile.

The 2344s show up now and then here and on E-bay. I even found a pair that were modified by JBL to have the ports behind the Buns. They work nice for my side H/T speakers where they need to be mounted flat to the wall.

I am about to try a 2426H driver with the bolt flange removed on a 2342 for a rear surround project. It is kind of a waste for that driver though. I have some 2416Hs too... so we shall see.

I'm glad Zilch stepped up with that link. I could never find it. I have it saved now.

[jerv]

Yes, it is the 2342. A slip of the finger.

Cabinets are ready, units are mounted. I have already made one version of the L200t crossover (as described in varoius other threads) and one (slightly simplified) version of the original crossover. These are fun to compare.

I am also working on a crossover design of my own (with somewhat steeper crossover slopes and different eq, taking care (among other things) of the annoying bump the 2214 has at 1,9kHz) and an also an electronic version. Needs something to do when winter sets in.

I'll report back with measurements and listening impressions in due time.

[Don Mascali]

Sounds like a great plan. Good listening.

Don M

[Dougie]

I'm in the process of building a 4425 DIY. Just for the fun of it, I plan to design new crossover networks in addition to replicating the originals. Maybe the difference (?) could provide some insight and learning experience.

However, somehow I seen to have gotten into some momentarily trouble with my soundcard/measuring gear, and need some verifying. Does anyone have impedance plots (or even better: impedance files) for the 2214H and the 2416H on 2344 horn?

Thanks, Espen

I happen to have a new pair ( not broken in ) of 2214-H drivers here. I could do an impedance/phase run on them this weekend with LMS if you like And post it in pdf format. I could also send you the pdf file via email for you to print. Let me know.

Dougie

[jerv]

Thanks, Dougie!

I very much appreciate your suggestion! However, I traced my problems to a faulty connector on the sound card, which is now fixed. I managed to get some good plots tonight. (Hope yours looks about the same).

Here are the frequency and impedance plots of the 2214H in my 4425-box:

[jerv]

And here are the plots for the 2416H on the 2342 horn:

[jerv]

I first tried with this variant of the L200t3 crossover, as in the thread http://audioheritage.org/vbulletin/s...ead.php?t=7110 which was a great inspiraton for my project.

[jerv]

Here are the simulation (top) and the real measurements (bottom) for the 2214H/2416H+2342 with the L200t3 variant crossover in 4425 cabinet. As you can see, these curves are quite similar. That means (I hope) that the simulation and measurements basically works.

[jerv]

The L200t3 variant crossover is within 5dB up to 2000Hz, but the range 2kHz - 15kHz is about 5 dB up. Listening tests confirm this find: IMO the speaker sounds a bit too bright with this crossover.

I will investigate new crossover values next. The 3,8 mH inductor for the 2214 is too big, and will be replaced with 3.0 mH (as in the stock L200t3 network).
So far, simulations may indicate that simple a Lpad in the HF section may be difficult without messing up the HF compensation. (Tne L200t3 network is very elegant, with the 2.2 uF capacitor functions as both crossover, compensation and attenuation). Maybe we will need a topology more in line with the standard 4425 network.

Or maybe something completely different. The 2214's response peak at 1,9 kHz looks quite annoying. Maybe some filtering or higher order slopes can fix it.

This is fun! I'll keep on soldering and listening.

Espen

[Zilch]

So far, simulations may indicate that simple a Lpad in the HF section may be difficult without messing up the HF compensation.

Try it, either at the front or back end (try both).

I see two problems, both of which you've already recognized:

1) You need more HF attenuation to balance with the 2214.

2) The slope of the compensation provided by the 2.2 uF is a bit too steep.

Lowering the 2.2 uF will get you more attenuation overall, but it'll "push" more power to the driver above 20 kHz, which I think is a bad thing, sonically. I'd find a way make padding work, instead.

Reducing R3 will do it, too, but the operating frequencies of the filter will also shift. Not a terribly big deal, since there's only 4 components total to "adjust."

Try some (relatively high) resistance in parallel with the 2.2 uF to lower the slope a bit. You may have to adjust the conjugate to restore the highpass rolloff, and it'll necessitate more attenuation.

You may have to put a notch filter in the LF to tame that 2214 peak. As you suggest, 3-pole would knock it down, too, but more of a "project."

Just to be sure, how did you achieve the 7.5 Ohms for L2?

This is fun! I'll keep on soldering and listening.

Yeah, it is!!

What's your measurement setup?

[John W]

The L200t3 variant crossover is within 5dB up to 2000Hz, but the range 2kHz - 15kHz is about 5 dB up. Listening tests confirm this find: IMO the speaker sounds a too bright with this crossover.

I found them a little too bright also. I ended up with a switch on the back that lets me change between 0, 3.5 and 6 db down on the upper end. I couldn't find the exact resistor values without opening them up, but normally use them on the -3.5db level.

[jerv]

Just to be sure, how did you achieve the 7.5 Ohms for L2?
......
What's your measurement setup?

- For the 1 mH / 7.5 ohm I used a 1 mH / 0.7 ohm inductor in series with 6.8 ohm.

- My measurement setup includes a Behringer ECM8000 condenser mic, Behringer UB1002 mixer (with phantom powering), a M-Audio Delta 1010 sound card (this card is way overkill for this application, but I use it for sound recording too) and a home made 2x75W amplifier. Software is justMLS, Speaker Workshokp and lspCAD for measuring and crossover simulations.