Subwoofer for hi-fi: 2242H vs 2245H.

[Doc Mark]

Greetings, Friends,

Well, my $30 2242H is going to have it's new dust cap, possibly today, and I'll soon be playing around with a box for it. Several of you have suggested, and it appears quite wisely, that the 2245H would actually be a much better choice for home hi-fi subwoofer use. So, I've been playing around with alignments for each woofer, and it appears that you may well be right.

I've been running graphs on the Linear Team site, and in most cases, the 2245H looks to give a flatter, more extended bass response, in similar cabinet size, than the 2242H. Hummmmmm......?????

I do not have, however, a 2245H against which I can compare the 2242H, which I DO have. So, in your collective opinions, should I dump my plans to use the 2242H for a hi-fi subwoofer, and replace it with a good 2245H? I could very probably sell the 2242H to someone who wants it for use in a more high power system than what I have in mind for home use. Or, if someone has a really good condition 2245H, and would rather have the 2242H, I might be open to a trade. Or, hell, I could just hang onto it, and use it for something else, "someday", and buy a good 2245H!

What do you think, my JBL Friends?? I want the best VLF sub I can get, for my intended purpose. My power will come from a Crown DC300A, in mono-mode, and we will very seldom require our system to really crank out the db's!! Should I stick with the 2242H, in an 8-10 cubic foot box, properly ported and EQ'ed, or go with the 2245H, in a similar-sized box, also properly ported? Thanks for any thoughts you might have on this! Take care, and God Bless!

Every Good Wish,
Doc

[pos]

I've been running graphs on the Linear Team site, and in most cases, the 2245H looks to give a flatter, more extended bass response, in similar cabinet size, than the 2242H. Hummmmmm......?????

Hi Doc

Don't let these simulations mislead you:
If you run a simulation with a similar box and tuning for the 2245H and 2242H keep in mind that the 2242H is 99dB/1W/1m whereas the 2245H is 95dB/1W/1m

If you look for SPL output you will see that infact the responses are quite similar below 80Hz, and that the 2242H rises to 99dB above that.

http://www.audioheritage.org/vbullet...46&postcount=3

That said, the response curve do not tell everything

[JBL 4645]

Hi Doc

Don't let these simulations mislead you:
If you run a simulation with a similar box and tuning for the 2245H and 2242H keep in mind that the 2242H is 99dB/1W/1m whereas the 2245H is 95dB/1W/1m

If you look for SPL output you will see that infact the responses are quite similar below 80Hz, and that the 2242H rises to 99dB above that.

http://www.audioheritage.org/vbullet...46&postcount=3

That said, the response curve do not tell everything

I think the 2245 off the top of my head is down 20Hz and was THX approved and they sounded and felt wicked with the original JBL THX specification at the Empire. I think the 2242 is 22Hz or 25Hz? It will still damage the home surroundings when played loud!

[johnaec]

You're really making this a lot more complicated than you need to. The speakers are designed for slightly different uses.

First, the main obvious difference is that the 2245 uses a foam surround, while the 2242 uses a corrugated one. Because of the greater compliance of the foam, it's able to more easily follow LF waveforms with accuracy, plus, it's not as stiff so its resonance frequency will be lower than the stiffer surround of the 2242. This means the 2245 is able to more accurately reproduce VLF than the 2242.

OK - so if the 2245 produces a little better VLF than the 2242, why even build the 2242? Mainly, because of live pro sound use. By using a corrugated surround, they lose a little bit of VLF, but there's no comparison in terms of reliability. When driving the 2245 and 2242 to concert sound levels, they foam surrounds just constantly wear out - they're not made for that kind of abuse. Hence the modifications to come up with speakers like the 2242, that are really made to take whatever you throw at them. That's why Scotty uses 2242's.

Fortunately, their fidelity is such that they can still be used for purposes other than pro sound.

So if you want the highest fidelity for home/studio use, the 2245 will give you a little more, but if you want something you'll never have to worry about, (with close to the same fidelity as the 2245), get the 2242.

That' my take, anyway...

John

[JBL 4645]

You need a large diy (MDF) enclosure kinder like the one that I have. It will give U.S.S. Enterprising impulse and warp factor 10 sound pressure!

You're really making this a lot more complicated than you need to. The speakers are designed for slightly different uses.

First, the main obvious difference is that the 2245 uses a foam surround, while the 2242 uses a corrugated one. Because of the greater compliance of the foam, it's able to more easily follow LF waveforms with accuracy, plus, it's not as stiff so its resonance frequency will be lower than the stiffer surround of the 2242. This means the 2245 is able to more accurately reproduce VLF than the 2242.

OK - so if the 2245 produces a little better VLF than the 2242, why even build the 2242? Mainly, because of live pro sound use. By using a corrugated surround, they lose a little bit of VLF, but there's no comparison in terms of reliability. When driving the 2245 and 2242 to concert sound levels, they foam surrounds just constantly wear out - they're not made for that kind of abuse. Hence the modifications to come up with speakers like the 2242, that are really made to take whatever you throw at them. That's why Scotty uses 2242's.

Fortunately, their fidelity is such that they can still be used for purposes other than pro sound.

So if you want the highest fidelity for home/studio use, the 2245 will give you a little more, but if you want something you'll never have to worry about, (with close to the same fidelity as the 2245), get the 2242.

That' my take, anyway...

John

Interesting fact that was! But why, why, why, is JBL shipping out 18” subs with cloth ribbon surrounds today, if they know this fact? Only issue I have is having to replace the foam, yes it easy providing its done right, but what dog’s dinner it can be sometimes.

I heard that the JBL 4645 was busted in a few times at the Empire Leicester Square with one of the THX trailer introductions with its original 13KW JBL THX seems like a task then of getting behind the screen and replacing the damaged driver! The original set consisted of x8 JBL 4645.

I prefer cloth ribbon its far more robust over foam.

[4313B]

So, I've been playing around with alignments for each woofer, and it appears that you may well be right.

Ya think!?

You're really making this a lot more complicated than you need to.

From glancing at the myriad threads that have been started recently with respect to this and the L300's I'm guessing you're probably right.


The JBL Model 4645 and JBL Model S1S originally used the 2245H. If I remember correctly it was 8 cu ft tuned to 30 Hz. At some point JBL changed the tuning frequency of these boxes to 25 Hz. I think some models still used the 2245H at that time and the 2245H's started suffering excessive casualties. The 2242H became available and it could handle all the power and abuse the original 2245H could not. The 2242H is designed to be used in larger numbers where mutual coupling fills in the VLF region very nicely. It can still be used in pairs just like it is in the current S1S but the 2245H is arguably a bit better in that role providing it isn't overdriven. The easiest thing to do with a DIY S1S or 4645 box is to bolt a 2242H or 2245H into it and then use a BX63A if desired. The 25 Hz tuning frequency of the newer S1S and 4645 boxes are functionally equivalent to the old B460 box.

[JBL 4645]

I like to see pictures Doc because I like pictures I like to see some pictures of the JBL 2245 from many angles because that is hot sub bass when fitted in the right enclosure.



I’ll show you a picture of my JBL 2240 if you show me your big huge 18” JBL 2245.

[toddalin]

Think W15GTI. You can get more LF extension in a box half the size of the 2245 and never worry about "overexcursion" or foam rot. Plus you can pick them up new for ~$250 (or less).

[Doc Mark]

Greetings, Friends,

Thanks, very much, for that additional information! I know, it seems as if you are repeating such things over and over again, and I guess in some ways, you are! But, it is much appreciated, in any case.

I rather liken LH to my stove collecting site, on which I am heading for 7,000 posts, not too long from now. I've been collecting old brass kerosene, Coleman fuel, and alcohol stoves, and gathering spare parts, and learning how to rebuild them, since the late 1970's-early 1980's, and in all that time, I have made enough mistakes that I can help keep new "Stovies" from making those same ones! Yes, it sometimes feels like those of us with more experience are repeating the same old stuff, over and over again (sound familiar), but we have to remember that those folks that asked the questions are new, and do not have the vast experience (read that: haven't made enough mistakes, yet!), that some others of us have!! Sometimes, I think that, if I have to tell one more person how to remove and properly rebuild an NRV (non-return valve), I'll go out and kick someone!!! But, I have to remember that, to a new person, this rather simple and mundane task is extremely daunting, and quite scary!! If a mistake is made, not only will the stove malfunction, but severe injury, conflagration, and even DEATH, can result!!!

So, just like you more experienced folks here at LH, over at the stove site, we have to help those with less experience, to keep them safe, happy, and healthy. And, in truth, that's what we want to do, anyway, even if it seems boring at times. Without new folks learning about them, our old, and very "obsolete" backpacking and expedition stoves will slip even further into the collective unconscienceness of history, and before too long, nobody will know a thing about them. Same with thing JBL, as far as I'm concerned!

So, please bear with me, and I'll try not to tax your patience, too much! I haven't built an enclosure for a good many years, and I've NEVER actually used a computer to model performance, prior to building. I have alway sat down with some rudimentary test gear, my calculator, a pencil, and some paper, and worked out the alignments as best I could. Hey, most of the time, they came out fairly well, to tell the truth!! But, all this computer modeling is new, and somewhat scary to me, especially when I see something different, depending on which program is doing the work for you!!

JBL4645, as to photos, I have none of the 2242H, Mate. But, I promise, after I pick it up from Edgewound, which might be today, or early next week, I'll snap a few and post them here. Fair enough?!

Thanks again, to one and all, for your suggestions. Even if you think otherwise, I AM learning from your wise counsel, and hope to end up with something good when I am finally finished with these projects! Take care, and God Bless!

Every Good Wish,
Doc

[hjames]

Think W15GTI. You can get more LF extension in a box half the size of the 2245 and never worry about "overexcursion" or foam rot. Plus you can pick them up new for ~$250 (or less).

Hmm cool - so - those look like some kinder Car speakers tho ...
Will they really play in the home?
Can I just stick one in my B380 for deeper sound?

[toddalin]

Hmm cool - so - those look like some kinder Car speakers tho ...
Will they really play in the home?
Can I just stick one in my B380 for deeper sound?

Yes, some kinder Car speaker... is that really a problem what the original intent was so long as it does the job?

Yes, they will play in your home, with authority, no less.





Possibly, but recognize that the surround sticks out further than the 2235 in your cabinet and this could hit your grill. Also, the speaker is much deeper (note the first picture) so you need adequate space behind it. I added some standoffs for my grill.

You can run them at 12 ohms and need lots of power (500+ watts).

[Allanvh5150]

I was going to run W15gti's in my theartre, Alpine make one that is on a similar level as well. The JBL is about $1500 here! Not that money really make a difference but instead I installed 4 2235's, which cost about $300 for the lot. They arent as power hungry as "car subs" but then again, why would we put car subs in anything but our cars?

[toddalin]

They arent as power hungry as "car subs" but then again, why would we put car subs in anything but our cars?

:dont-know Maybe, because they work better in that range, can be put into a smaller cabinet, are more readily available, are cheaper, are almost indestructable, carry a longer warrantee, not as prone to sun fade and rot, never bottom out, and never get foam rot??? Seems logical to me.

[Allanvh5150]

I knew that would get a bite out of you.
I do love the car subs as well but only in my car.
I will post some pics later of where my subs are positioned. They are both huge cabinets that are burried in the wall which just happens to be the downstairs roofspace.

[toddalin]

I was going to run W15gti's in my theartre, Alpine make one that is on a similar level as well. The JBL is about $1500 here! Not that money really make a difference but instead I installed 4 2235's, which cost about $300 for the lot. They arent as power hungry as "car subs" but then again, why would we put car subs in anything but our cars?

OT, but do you know the Sullivan's in Christchurch? They now have my '70 Corvette roadster that I restored, as well as a '63 split window. Maybe you've seen my old roadster running around town. Its Donneybrook Green with green interior and a white convertable top. If you see them, say hi to them for me.

Todd