2235H and phasing/polarity JBL 4430

[Russellc]

I have been using 2235H quite successfully in 4507 cabinets in a two way configuration. 2235H is like many JBL woofers, in that it provides forward movement from a + signal on the black post. Looking at the schematic for the 4430 crossover, I noticed for the first time that + appears to be hooked up to the red (+) post of the 2235H woofer.

Can anyone explain why this is? When using a "non" 4430 crossover, I have always hooked + up to black to get the best bass response. I have the parts and will soon be building a clone 4430 crossover and was wondering about this situation, and if anyone could explain the woofer phasing in the 4430 crossover.

Many thanks in advance,

Russellc

[Earl K]

(The) 2235H is like many JBL woofers, in that it provides forward movement from a + signal on the black post. Looking at the schematic for the 4430 crossover, I noticed for the first time that + appears to be hooked up to the red (+) post of the 2235H woofer.

Can anyone explain why this is?

- Tradition has one flipping the polarity on either the LF ( or HF transducer ) as standard fare when one is implementing a 2-pole network .

WHY ?
- Each half of a 2-pole network puts the ( bandstop ) phase response, 90 degrees out of phase from the ( bandpass ) signal ( at the 3 db down point ).
- Utimately, each bandstop signal reaches a full 180 degree rotation a couple octaves away from the bandpass area.
- BTW, we are mostly listening to the "bandpass" signal .
- Each half of a ( 2-pole network ) , forces the ( above mentioned 90 degree ) phase rotation in opposite directions . This is why at the crossover point , frequencies within the immediate area will be 180 degrees out of phase to each other . The 180 degrees phase difference ( caused by two , 90 degree rotations in opposite directions ) will result in some severe cancellation for a select group of frequencies .
- Flipping the polarity on one ( but not both ) of the transducers ends up putting those frequencies ( only within the crossover region ) in phase with each other . By doing this, they add together ( rather than cancel ) .
- An unavoidable consequence of this ( typical ) practice is that the 2 halves of a 2-way speaker no longer act as one unit having the same polarity ( forward motion , et all ) . Some claim to hear this / while others can't .
- One can mostly avoid this ( polarity flipping ) by using 4-pole networks .

When using a "non" 4430 crossover, I have always hooked + up to black to get the best bass response. I have the parts and will soon be building a clone 4430 crossover and was wondering about this situation, and if anyone could explain the woofer phasing in the 4430 crossover.

- The two halves of the 4430 network are still 2-pole ( even with the Zobel & the HF compensation portions in place ) .
- JBLs' ( backward ) color-coded polarity convention merely serves to obscure & confuse those who don't understand the basic tenants ( of phase changes / ie; phase rotations caused by filters ).

>< cheers

ps; Everything mentioned above ( to achieve summing at the crossover point ) assumes the voicecoils are in alignment and that the acoustic centers align at the chosen crossover frequency .

[Doc Mark]

Hi, All,

Dang! I'm almost afraid to post this.... but, when we got our L300's, the 2235H's were hooked up with red being the +! I've used them that way ever since, and think their bass response, overall, is simply wonderful! Now, I may have to swap them around, and see what happens..... Hummmmm...... !! How about any other L300 owners? Red = hot, or not?? Take care, and God Bless!

Every Good Wish,
Doc (who may well be "out of phase", but who seems to like it!)

[4313B]

How about any other L300 owners?

Just hook them up like the Owner's Manual states and forget about it.

*****

Well Harman's copy is kind of crappy. Maybe someday I'll scan mine in and put it in the Library. Those were nice little booklets back then. It was a nice era.

[Robh3606]

Just a point of clarification the 4430 network has both drivers in phase. They don't reverse phase on either driver. Both the 2235 and the 2426 are negative polarity drivers.

Rob

[Doc Mark]

Just hook them up like the Owner's Manual states and forget about it.

*****

Well Harman's copy is kind of crappy. Maybe someday I'll scan mine in and put it in the Library. Those were nice little booklets back then. It was a nice era.

Hi, 4313B,

I did not buy my L300's new, and as such, did not receive an owner's manual with them. However, I did copy one that I thought I got from our Library.... but it might have been from someplace else. It's the "L300 Summit Instruction Manual". Unfortunately, it does not tell me about hooking up the individual drivers, and I removed them when I horsed those huge cabinets up the stairs an into the house. I did note how they were hooked up before I removed the drivers, and reinstalled them just as they were. But, I seem to remember that positive went to red on all three drivers. I'd appreciate the info on hooking up the individual drivers, as it's more than possible, being the L300's third owner (as far as I know...), that the drivers have been hooked up wrong at sometime in their past. Thanks, very much, and God Bless!

Every Good Wish,
Doc (puzzled, but still learning, even at his advanced age of "decrepitude"!)

[4313B]

One version of the Owner's Manual did have the individual driver hook-ups shown.

You can find the tech sheet which will also show it in this list:

http://audioheritage.org/vbulletin/f...splay.php?f=60

[Doc Mark]

Hi, 4313B,

Outstanding! That's perfect! I'll check to see if I did it that way, and if not, change things to the way they should be. MANY thanks, my Friend! Take care, and God Bless!

Every Good Wish,
Doc (comes the dawn, thanks for you, Sir!)

P.S. If I DID hook the L300's up incorrectly, I'm looking forward to hearing them, once done properly!

[Earl K]

Hi,

The following was a very worthwhile clarification from Rob. ( I've added some caveats & addenda to my original post to hopefully make it more lucid ) .

Just a point of clarification the 4430 network has both drivers in phase. They don't reverse phase on either driver. Both the 2235 and the 2426 are negative polarity drivers.

- One needs to look to the concept of acoustic-centers to understand this apparent paradox .

- Heavy coned woofers ( like the 2235H & my ME150H ) have frequency dependant acoustic-centers that can occur behind the actual voicecoil .

- ie; As frequencies are reproduced at the upper extremes of a woofers' bandpass, the apparent source for these frequencies will be found to be further behind the woofers' voice-coil ( than say a frequency 1 octave below ) . It's caused by a mechanical form of propagation delay ( though you'll also find that some claim it's all due to the high inductance values of todays modern high-power voice-coils) .

- I run into this phenomena with my heavy coned woofers ( le14H & ME150H ) .

RE; the 4430
- I'm guessing that the relationship formed between the aligned voice-coils and the woofers' acoustic center is approximate 1/2 a wavelength ( at 1000hz ) . That would be in the neighbourhood of @ 6.75" .
- This 1/2 wavelength offset will represent the necessary phase rotation ( accomplished acoustically ) to allow proper summing of the electrical filters ( at crossover ) .

>< cheers

[boputnam]

P.S. If I DID hook the L300's up incorrectly, I'm looking forward to hearing them, once done properly!

Doc, if by-chance you did have 'em "backwards", it will not be so great a revelation once inverted. Why? The woofers are still doing their part, faithfully.

The issue is the combined response of the LF with the MF in the area of crossover. You might notice an improved balance in the zone of crossover once "correct". That is, if in-phase, there will be a summing of the two in the crossover, vs a cancellation. Or, the converse. You can imagine what the response curve would look like (and sound like) in either case.

[Russellc]

Thank you for the answers and insights into these drivers and their use in the associated speakers, much to learn here to be sure.

Cheers,

Russellc

[Doc Mark]

Hey, Bo,

Many thanks for that extra bit of info. Right now, I'm listening to the 4411's, with the 4645 finally added, and must say that they sound very nice, indeed! The subwoofer, with 2242H installed, crossed at 80HZ, is adding exactly what I was "missing" before, when I first got the 4411's. Neat! Whilst I enjoy them, I'll check out the L300's, and see what I did, if anything. I'll report back with whatever I find out, good, or bad, and take my lumps like a good little JBL-ista, if I messed up in originally installing the drivers! Thanks, again, and God Bless!

Every Good Wish,
Doc

[Doc Mark]

Hi, All,

Whilst enjoying the 4411's, and the 4645 sub, I removed the back panels on the L300's, and took a peek inside. Here are the results:

- Woofer hooked up green to red, and black to black, as per JBL spec for the L300.

- Midrange hooked up white to redd, and black to black, as per JBL spec for the L300.

- High Freq hooked up yellow to red, and black to black, which is backwards to JBL spec for the L300!!

SO, it's not the woofers, or mids, that have been hooked up backwards, but the slot tweeters, instead!! The thing that makes all this very interesting, is that I never removed the 077's, when I carried the otherwise empty cabinets up into our home. That means that someone in the past, one of the two previous owners, or some tech, swapped the wires, and they have been that way ever since. Hummmm...... Am I going to gain less of a phase shift in the MF/HF when I swap the wires? That's what I'm thinking will happen, but I'd love to hear from those that know, for sure. I've enjoyed those 077's just as they are, but may even like them better, once they have been wired correctly. What say you, JBL Friends? Thanks, very much, to one and all who jumped in on this! Take care, and God Bless!

Every Good Wish,
Doc

[Russellc]

Hi, All,

Whilst enjoying the 4411's, and the 4645 sub, I removed the back panels on the L300's, and took a peek inside. Here are the results:

- Woofer hooked up green to red, and black to black, as per JBL spec for the L300.

- Midrange hooked up white to redd, and black to black, as per JBL spec for the L300.

- High Freq hooked up yellow to red, and black to black, which is backwards to JBL spec for the L300!!

SO, it's not the woofers, or mids, that have been hooked up backwards, but the slot tweeters, instead!! The thing that makes all this very interesting, is that I never removed the 077's, when I carried the otherwise empty cabinets up into our home. That means that someone in the past, one of the two previous owners, or some tech, swapped the wires, and they have been that way ever since. Hummmm...... Am I going to gain less of a phase shift in the MF/HF when I swap the wires? That's what I'm thinking will happen, but I'd love to hear from those that know, for sure. I've enjoyed those 077's just as they are, but may even like them better, once they have been wired correctly. What say you, JBL Friends? Thanks, very much, to one and all who jumped in on this! Take care, and God Bless!

Every Good Wish,
Doc

Any difference in performance? Inquiring minds want to know!

russellc

[toddalin]

Hi, All,

Whilst enjoying the 4411's, and the 4645 sub, I removed the back panels on the L300's, and took a peek inside. Here are the results:

- Woofer hooked up green to red, and black to black, as per JBL spec for the L300.

- Midrange hooked up white to redd, and black to black, as per JBL spec for the L300.

- High Freq hooked up yellow to red, and black to black, which is backwards to JBL spec for the L300!!

SO, it's not the woofers, or mids, that have been hooked up backwards, but the slot tweeters, instead!! The thing that makes all this very interesting, is that I never removed the 077's, when I carried the otherwise empty cabinets up into our home. That means that someone in the past, one of the two previous owners, or some tech, swapped the wires, and they have been that way ever since. Hummmm...... Am I going to gain less of a phase shift in the MF/HF when I swap the wires? That's what I'm thinking will happen, but I'd love to hear from those that know, for sure. I've enjoyed those 077's just as they are, but may even like them better, once they have been wired correctly. What say you, JBL Friends? Thanks, very much, to one and all who jumped in on this! Take care, and God Bless!

Every Good Wish,
Doc

When I do this swap, it is really hard to tell which way is preferential. I use the Behringer, and each way has its positives and negatives (peaks and valleys), and there really is no clear winner here like I see with the woofer/mid phasing.