Jubal L65 woofer, midrange and tweeter phase.

HelloIts been a while since I have posted here. I am currently working on my house and my main system is disabled. I was missing the music so I put together a little system. Jolida JD5 pre and JD9 phono, Yamaha M80 amp and Technics SL10. Digital is Topping D90LE fed by a computer lossless flac files.The Jubals I had to replace the 126 woofers with 128 woofers. While doing that I did rebuild the crossovers. Everything was done correctly and these were my listeners about 8 years ago then to L300 and to the current 4343b.It seemed a little bright to me. Perhaps that is the case coming from 4343b speakers. Anyway a while back I purchased a tool that will measure if the speaker is in phase or not. The woofer and the midrange look to be in phase but the tweeter seems to be out of phase. I did read from a google search that some speaker are designed this way. Is this normal for the Jubals? Is this the way they were designed? Thanks

https://www.amazon.com/Speaker-Posit...66780858&psc=1

Not sure why it bunched together. Tried editing but no go so please ignore the sloppiness.

warpig,

Since nobody else replied, then i try to help orphans...

To avoid the text being bundled all together, i write in WordPad with double space between paragraphs and then copy and paste the text to LH forum. If i use a single space between para i get what you got, so its a work around...

Based on the info i have, the L65 uses 126A, L65A 122A and L65B 129H. I didn't see a 128 in stock form.

That being said, a few things that come to mind. Do 126 and 128 obey the same driver polarity convention? A while back JBL used the black woofer terminal as positive, but later switched to red terminal being positive. Could it be that going from the 126 to the 128 the polarity convention applicable changed in the meantime for the replacement driver?

I'm not familiar with the Jubal's crossover details, however JBL used many 12 db/oct. crossovers, assuming it might be one of those, since its a 3-way system usually the polarity of the mid driver is reversed compared to that of the woofer and tweeter.

Therefore having the same polarity for woofer and mid, then a different one for the tweeter would seem strange to me.

Richard

Jbl l65

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Originally Posted by warpig

Not sure why it bunched together. Tried editing but no go so please ignore the sloppiness.

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There was a discussion about this some time ago. As I recall, a simple settings change made it work. I'm sure Heather knows how to find that post. I can't.

Just to show you . . .

That is it working . . .

All the best.

:)

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Originally Posted by Odd

Jbl l65

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Yes, but since JBL schematics seldom show driver polarity, I don't see this answering the OP's question. That has often been a source of frustration if the connectors aren't idiot-proof.

BMWCCA. I agree.
Here is more information;

https://www.audioheritage.org/vbulle...out-schematics

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Originally Posted by BMWCCA

Yes, but since JBL schematics seldom show driver polarity, I don't see this answering the OP's question. That has often been a source of frustration if the connectors aren't idiot-proof.

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Agree. Also I do believe my schematic is the 1st one at the top.

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Originally Posted by Odd

BMWCCA. I agree.Here is more information;https://www.audioheritage.org/vbulle...out-schematics

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Thanks all. The above thread does explane the phase issue with the N65 and the rest of the L65 schematics. When I replaced the 126 with the 128H I may have switched the polarity. Thinking at the time that the 128H was designed and needs to be in phase to work properly where as the 126 was designed and to operate out of phase. Will the 128h work properly out of phase? Again thanks all.

The polarity of the drivers will only affect the sound in the crossover region(s). If it is incorrect you will create a fairly narrow notch centered around the crossover frequency.

If the sound is too bright, look at the most obvious first. Try padding down the HF driver.


Widget

So should I wire it as the N65 schematic shows? Also not quite sure I understand The polarity of the drivers will only affect the sound in the crossover region(s). If it is incorrect you will create a fairly narrow notch centered around the crossover frequency.

I had this link bookmarked and Bo stated You own the first iteration of the L65's (nice!). My notes say the 128H is an "acoustic replacement" for the 126A, but if you go that route, note that you should connect the 128H as GRN to Black LF terminal to maintain JBL factory polarity. I really need to check the wiring its been a long time since I worked on them. https://www.audioheritage.org/vbulle...ll=1#post14243

Just an update. I did pull the 128 woofers and the green wire was going to the red post. I did as Bo suggested and put the green to the black post. They do seem to sound better and think I am going to leave them alone.

Thanks to everyone for the responses and help. Hope I am not to much of a pain I am just trying to understand.

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Originally Posted by warpig

So should I wire it as the N65 schematic shows?

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I haven't studied your situation so I am not sure.

Quote:

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Originally Posted by warpig

Also not quite sure I understand, "The polarity of the drivers will only affect the sound in the crossover region(s). If it is incorrect you will create a fairly narrow notch centered around the crossover frequency."

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Understand that when you have one driver out of phase with the other you will experience cancellation.

What this means in this case is that in a crossover between two speaker drivers, say a 500Hz crossover, if the drivers are in phase you should have a roughly flat frequency response at and around 500Hz. If the drivers are out of phase then there will be a cancellation at 500Hz. The slope of the crossover will determine the depth and width of the notch.


Widget

Thanks and the cancelation was what I was worried about not necessarily making the speaker bright but some frequency's being canceled. Well they are wired as JBL would have them for the N65 network. They do sound better.

Again thanks all.