J's & H's and Compression Drivers & More

[BigT]

A few random questions.

I am trying to gather drivers together for a speaker project. It will probably use two woofers per side. The one woofer I have is an "H" - 8 ohm - and there is also a "J" version - 16 ohm. I'd rather have all J's but it seems to rather a rare woofer - at least they're rare on Ebay - and I may not be able to find all of one version. But maybe I can find two of each. Anyone mix H and J versions together? One H and one J in each speaker. I don't expect this is a problem, so long as the amplifier is stable in the load, but maybe I'm missing something.

I'm new to horns. They're a bit of a mystery to me, but I'm picking up bits and pieces. The horn I'll probably use is the JBL 2382A, but what compression driver is best? I know the 2450 and 2446 series will work, and I'll likely find the 2446 cheaper. How about the more common 2445 series? What is better about the 2446 over the 2445? I know there are some older drivers that will fit, according to the spec sheet, but I'm a bit leery about them.

Several places have mentioned horn equalization. Does anyone use it, how do you do it, and how will I know what the correct equalization is? Is this a subjective thing or is there a standard for each horn?

Thanks!

[blackwell]

A few random questions.

I am trying to gather drivers together for a speaker project. It will probably use two woofers per side. The one woofer I have is an "H" - 8 ohm - and there is also a "J" version - 16 ohm. ...

I know there are some older drivers that will fit, according to the spec sheet, but I'm a bit leery about them.

Several places have mentioned horn equalization. Does anyone use it, how do you do it, and how will I know what the correct equalization is? Is this a subjective thing or is there a standard for each horn?

Thanks!

Recone one of them. It's just not going to work well for you to mix 8 and 16 ohms, especially trying to get equal output. Although, I suppose you could run them across different frequencies. For example, use a cascade type crossover, ala 4435. Run the 16 ohm across a wide range, tune the cabinet very low so you get an extended bass shelf, then run the 8 ohm driver in parallel with the 16 ohm but with a 12mH coil in series with the 8 ohm driver. This will fill up the low end but may still have a bump there because the 8 ohm driver will be louder. Just something to think about.

Old compression drivers can be very nice but you need to fill in the top end with a 2405 or something. Also, don't over power the old ones

EQ'ing horns is all about getting rid of the honk, a broad bandreject. This also helps pad it down to match your woofer but you still will need a little more padding. Then if your using a CD type horn you may need to keep the higher frequencies hotter because your spreading them all around the room. The net effect is that the CD horn won't seem as bright. All of these EQ filters interact with each other especially if done passively, so you need to get an idea of what your response looks like and then decide how best to cut the hot areas down to give you the widest, flatest response. Good luck.

[Cyclotronguy]

I've done this in what we would call a 2-1/2 way I suppose. Used the 8 ohm woofer normally and took the 16 ohm woofer and a big choke in series and made it the helper woofer. The 16 ohm of course had much lower output... but that was just what was desired. Helper woofer only covered the range from Fs - 200 Hz.

Cyclotronguy

[BigT]

Looks like I won't be running unmatched woofers. I don't need any extra complexity right now. It's ok - I've got plenty of time to find what I need.

The woofer is the 2220H - it seems to be the most efficient woofer I can find. Is the 2220A basically the same thing?

I will very likely be using an active crossover. Anyone use an active crossover for horn equalization? Which crossover was it? The horn is a 2382A - does this one need much equalization? Don't know which compression driver yet.

[Zilch]

Indeed, it appears there are different impedance versions of 2220, from the Transducer Parts List:

2220A = 8 Ohms
2220B = 16 Ohms
2220C = 16 Ohms

2220H = 8 Ohms
2220J = 16 Ohms

A, B, and C are Alnico, I would assume, H and J having ferrite magnets. The difference between B and C may be known to others, or discussed somewhere in the forums.

Review the datasheet for the 2382A horn. It's constant directivity, and will therefore require compensation. Does the CD EQ built into any available active crossover match what is required? Not in detail, probably, though you may get lucky and come close.

Regarding the compression driver question, 2446 adds coherent wave phase plug, as I recall. Look this stuff up on the factory datasheets to be sure....

[speakerdave]

Possibly the 2220C was a JBL Pro counterpart for the 130B, a "32 ohm" job that may have been hatched in the same flex-ohm strategy that was the source of many JBL 16 ohm drivers. The 130B crop up only occasionally on ebay and go for high prices. (Or maybe JBL feels no one really needs a 32 ohm driver any more.) I have some 2220B's on hand. The DCR shows they are truly 16 ohm drivers.

David

[blackwell]

Looks like I won't be running unmatched woofters. I don't need any extra complexity right now. It's ok - I've got plenty of time to find what I need.

The woofer is the 2220H - it seems to be the most efficient woofer I can find. Is the 2220A basically the same thing?

I will very likely be using an active crossover. Anyone use an active crossover for horn equalization? Which crossover was it? The horn is a 2382A - does this one need much equalization? Don't know which compression driver yet.

I'm sorry, but the 2220 is a poor woofer for normal enclosures. The only place that I have found that they work well in is a horn loaded situation like a klipsch corner horn. The Q is so low that they just don't have any bass in a closed or vented cabinet. You can get a lot out of it for 100Hz up, but nothing to speak of below that.

Eric

[BigT]

I'm sorry, but the 2220 is a poor woofer for normal enclosures. The only place that I have found that they work well in is a horn loaded situation like a klipsch corner horn. The Q is so low that they just don't have any bass in a closed or vented cabinet. You can get a lot out of it for 100Hz up, but nothing to speak of below that.

Eric

Yes, I quite understand that the 2220 is not intended for low bass. Part 2 of my project will be subwoofers. My goal for Part 1 is efficency. I once owned Klipschorns in the mid-70's but sold them when I came under the influence of those "underground" rags. Once in a while I get nostalgic for the easy dynamics and sharpness that was Klipsch, and this is one of those times. This is the first time I've actually invested in drivers to do something about it, though. I no longer want Klipschorns; I have a tough time with that midrange horn going down to 400Hz and the woofer section doesn't go low enough for these modern times, although in their day, when vinyl was king, they went low enough.

[Zilch]

What woofers are you talking about?

Run an 8 and a 16 in parallel, and the 8's gonna get 2/3 of the total power, no?

That is if they actually ARE 8 vs. 16 ohms.

Clone a stock design....

[Thom]

What woofers are you talking about?

Run an 8 and a 16 in parallel, and the 8's gonna get 2/3 of the total power, no?

That is if they actually ARE 8 vs. 16 ohms.

Clone a stock design....

If you put them in series and dropped just the right value resister across the 16 you could give them equal power except that the value would be a moving target plus it's probably too wierd.