2122H Questions

[Rex Mills]

I have a pair of 2122H that I've been sitting on from the Tent Sale and rather than building cabinets have decided to mount them in .7 cu. ft. enclosures rather than the JBL recommended .25. What, if any, transient response negatives might I encounter in the larger box. They will be actively crossed over at 300 hz 4th order. And what was JBL's original application for the 2122H.

[4313B]

Transient response will suffer a bit. Efficiency will drop a bit above ~ 150 Hz and increase a bit below ~ 150 Hz. I probably wouldn't go bigger than 0.4 to 0.5 cubic feet myself. 0.25 was the target volume for a B2 Butterworth response where Qtc = 1/sqrt(2). 0.4 to 0.5 will put you in the BL2 Bessel response where Qtc = 1/sqrt(3).

The 2122H was used in the 4344 and 4345 Studio Monsters.

I personally like it the best of the JBL midbass transducers with the 2108H a very close second.

[Robh3606]

I have them in the same application. I used the recommended enclosure size. They sound great! What kind of cabinet you building?? I used a 10" Sonotube/concrete pillar tube as my subenclosure. Worked fine. What are crossing the hign end at and what will the rest of your system components be??

Rob:)

[Mr. Widget]

Rex,

Someone posted an easy fix for reducing the internal volume of existing cabinets on the previous forum. You can put a sand bag or two in there. It will also add mass, a side benefit.

[Mr. Widget]

You can hot glue or silicone a sand bag to the back of the cabinet.

[Ian Mackenzie]

Yeah,

You have my vote for the 2122, I have them in 14 Litre (0.5 cu ft boxes).

The 4th order might be too steep @ 300 hz for a woofer midrange crossover as it can sound too abrupt for hifi.

JBL uses 2nd order tailored slopes for their networks and a special card for their 5234a active network, or consider 18 db slopes.

Ian

[Earl K]

Hi
Originally posted by Giskard
The 2122H was used in the 4344 and 4345 Studio Monsters.

I personally like it the best of the JBL midbass transducers with the 2108H a very close second.

Forgive me if we've gone through this in previous forums ( my notes for the last forum were tragically incomplete & then, of course it sank into digital chaos ). I have le10a , 10h & h-1, 2123H & 2012H ten inchers and this discussion is making me somehow feel deprived.

So

What really is a 2122H ? Is it a 2123h with a high compliance surround, weighted down to match the mid efficiency 2235H woofer family ? Does it have a different coil ? Is there a mass ring involved ? Is the cone aquaplassed ? Should I be building one out of spare parts ? :confused:

Okay I'll shutup now and enjoy what I have . :)

Thanks !!!

regards <. Earl K

[4313B]

Hi Earl,

"this discussion is making me somehow feel deprived"

Better deprived than depraved?

"What really is a 2122H ?"

It's an "improved" 2121/2121H as used in the venerable 4343/4343B. Think LE10H without aquaplas. The 2121 was essentially an LE10A without aquaplas, same inverted dome. No mass rings.

Different coil, 52 turns as opposed to the LE10H's 82 turns (early) and 86 turns (late).

Not weighted down to kill efficiency to match the 2235H/2245H but rather to smooth response and increase bandwidth. It's bandwidth is greater than the newer 2123H. It's smoother than the 2123H and goes lower but it can't handle the power and doesn't have the efficiency of the 2123H. The 2108/2108H is it's 8-inch cousin. Same magnetic assembly and 3-inch edgewound copper ribbon voice coil. Used in the 4315/4315B. Awesome midbass transducers.

[Earl K]

Hi Rob
Better deprived than depraved?
Well perhaps depraved would be my dropping my extra le10a kit into a 2012h motor.:eek: ( That ought to result in a rise in the final Fs , closer to the 40 hz of the 2122 with increased motional control from the 2012s' super deep gap ). ;)

regards <. Earl K

[Rex Mills]

You guys have given some good things to consider. The original question about the .7 cu.ft. cabinet was asked because I have an already built .7 box. I think addng some bracing and glue blocks to reduce volume is the way I'll go. My plan is to use as much of the stuff I have now without getting out the tablesaw. So far the components look like 4648A, 2122h, 811 B horns with 902-8B drivers and the tent sale 2402H-05, bullets with 2405 diaphragms, if needed. The 4th order slopes are from an available pair of older Madisound Sledgehammer active xovers, so I am pretty much tied to them for now. The 4648's may go on the block if I can find a nice pair of 2235's or 2245's though. Wide bandwidth and efficiency is the goal, loud enough to hear Otis Redding when I'm mowing the grass is just about right. Amen!

[Robh3606]

"loud enough to hear Otis Redding when I'm mowing the grass is just about right. Amen!"

Quote of the day! LOL

Rob:)

[Mr. Widget]

So I read that and started thinking about how great it would be to have a lawn.

I live in a warehouse in a very urban area. I usually don't miss the tree lined neighborhood type thing as it reminds me of the days when the neighbors would complain about "the noise" ... it was only music. Some how though, the thought of having a warm summer day and a lawn to mow listening to Otis... just sounds great!

[Ken Pachkowsky]

Tell ya what Widjy, I have lots of grass out here and you can mow to your hearts content. I'll even throw Otis on for ya?

Let me know, I'll forward the address, supply the gas and beer.

Was funny though..

Ken

[Rex Mills]

I live in a semi-rural location and have a 2 acre lot that I have to mow and after 4 years and 2 lawn tractors the only thing that makes that chore bearable is knowing I can listen to some good tunes while I'm outside working. The neighbors houses are a couple hundred feet from mine and I put a pair of L-19's out on the back deck and fire them up when I'm outdoors. Speaking of neighbors, one of mine is a contractor who came across a pair of Altec 9864's when he was doing work at a local skating rink. I am doing everthing, I can think of, to get my hands on them and just this morning found them in the library pages of this site. Wish me luck.


http://www.lansingheritage.org/html/altec/specs/pro-speakers/9864.htm

[Mr. Widget]

Funny how these threads derail.

That is an interesting looking speaker. Have you heard them? I would bet they are not very Hi-Fi/Studio Monitor.

Bet they can over power your lawn mower!

[Rex Mills]

Yes, these threads do get O.T. don't they. I haven't heard the Altecs yet, High Fidelity, probably not, but from an historical standpoint, they would be cool to have. I'm betting Altec made very few of them considering their timeline and the subsequent ownership by Gulton, Mark IV, EVI, and Telex.Since my neighbor is not a HiFi sort of guy and probably got them for nothing, I bet I can get them for a couple hundred bucks. He's happy and I got a pair of unique Altecs, Win/Win.