250 TI internal wiring

[opimax]

Today I bridged my Adcoms on the the 250TI, 400 each :applaud: , certainly loud! While we were re wiring the connections I wanted to test the phase of the speakers. I knew they had been refoamed so it is trust but verify. When I tested the speakers it appears the woofer were reversed. I used a D 1.5 V battery to check. Putting positive to positive and neg to neg the cone wouild move in, both speakers. Removed the woofers and switched connections.tested again and was good. I also tested my L20T3s which currently are just sitiing on top of the 250s.They were correct

My question is about the wiring. The black wire from Xover was on the neg and the green wire was on the pos, and I switched them. Tested again now correct. I thought that the green would have been + and the black - but again this is backwards to what I observed. I also checked the mid woof by touch for movement, hard to be sure, but seemed correct as it was.

If this the end of this issue great but if something is wrong I want to fix it. I will wait before I do anything else

Thanks for the advice

Mark
It appears to have more bass now but it could either I am giving them more power or i am hearing things that I want to hear....:bouncy:

[Zilch]

Black goes to the black terminal, and green goes to the red one.

http://manuals.harman.com/JBL/HOM/Technical%20Sheet/250Ti%20ts.pdf

[opimax]

Thanks Zilch

Then something is wrong here or is my test method flawed? Also it shows Orn I guess is GRN, and then GRN/Black There is no grn on the black wire at all(looking for a stripe of green)?? SOmeone could have upgraded the wiring maybe??

I can see GRN for the tweeter so ORN should be orange maybe yet I have green, maybe again somebody has been inside. Could someone tell me where the wires connect on the Xover to see if they are correct? I am not able to read a schemantic (or spell it :) )

I am confused. Is it possible to get the wires backwards when reconing/refoaming on the speaker itself so the terminals on the speaker are reversed?

[Zilch]

It is unlikely that the leads were reversed on refoaming. They'd have to be crossed.

Yes, I think the color codes are wrong on the Tech sheet. JBL convention is green and black (or green/black) for the LF driver.

Are your woofers LE14H-1? Do they have the label on them at the terminals saying they are wired for AES positive polarity?

Was your battery test done on the woofer itself, or the speaker cabinet input terminals?

The reason is apparent in the schematic: The polarity is reversed. If they are AES positive, then they would push out with battery (+) to cabinet input (+). I can't tell anything for certain until you tell me how the woofer itself behaves. If it's AES positive, it will push out with battery (+) to red.

Note also, that JBL sometimes reverses the polarity of some of the drivers intentionally in the final cabinet alignments. The tweeter is apparently flipped in your 250Ti, for example, as is the 108H. It IS confusing, but since the leads and terminals on all drivers but the woofer are polarized, it'd take considerable effort to get them wrong.

Further confusing the issues, I see no indication on the schematic whether E101 or E102 is cabinet (+) red. I'm making some assumptions here. Follow E102, which I assume is black, or cabinet (-). It connects to (+) on two of the drivers.... :banghead:

See here for clarity. It tells which way the cones should move:

http://manuals.harman.com/JBL/HOM/Technical%20Sheet/250TiBQ%20ts.pdf

[And also gets the wire colors right, presumably.... :p ]

[opimax]

I have pulled the 120ti woofer (rears) because it was doing the same and to see how bad the hole in the foam is :( BAD , 128h labeled hard to read in white lettering(sn 013087). I hooked the battery to the terminals and it still was reversed so it must be that way for this series. The wiring is the same as you said, green and black w/black to negative. there was no AES marked on the this woofer though. FWIW, Woofer pointed up, red terminal on left

I was under the impression the battery test was a constant at least at theterminals, Thanks for the lesson :bouncy:

I will now go change back the 250 to where they should be :) I will check for AES if the monsters cooperate, they are supposed to be 14-1!! :)... Are the Sn worth getting for anybody or anything?

I actually did notice :D in the diagram that they showed different size spade looking connectors but neither the 128 h or the 14-1 which I have use those connectors. They both have spring loaded w/tinned leads:dont-know

Should refoaming be done in both speakers at the same time or is it OK to do just the one needed? i can tell they were done before, cone is on top of the foam, hope that is correct. a friend and I will refoam this, good practice :)

Thanks as always

Mark

[Zilch]

Good deal, Mark. JBL woofers typically pull in when battery (+) is connected to the red terminal, though there are a few exceptions, and the cabinets are usually wired the same.

The pro cabinets are a different story. Read up here:

http://www.jblpro.com/tech-library/JBL_TechNoteN1V12C_v5.pdf

It's in the first paragraph.... ;)

[opimax]

I just swapped the connection back on the 1st woof, didn't actually pull it out. The 2nd is on the floor. Both had a white dot/blob on the frame on top towards the seal gasket which really couldn't be read but may have said something or is a "D" , but it is old and faded. maybe this is the AES sticker your referred to...

SN for this woof is 4175

FYI,On the underside of the cone hand written in white is LE14h-1 7/16/86.
It too is reversed at the terminals when tested

Now back to Bill Chase , screaming trumpets poorly recorded on vinyl then copied to CD but no fatigue when listening now a days.:p

Mark

Actually i will a few in case there is anything else I can do to do while a part

[opimax]

I just read the article, a slightly off topic story/thought

The other JBL speakeers I have played with are the ProIII which are current and are standard. The L20T3 bought at about the same time this month or so are newer and as i said ealier also "conform" then I test these w/no prior JBL knowledge and get confused until now :)

But in late 70s I think ?? I was so in love w/L100s in the U of MD library listening rooms I boght the drivers from Crutchfield in VA. they were sold as a set and I made sure my cars had a larger rear deck (either it was a Ply Fury or Duster). they were install on the rear deck in a box, but not sealed tight?? (made by Crutchfield :( ) . no matter what I did they never sounded good.

So many factors here why but I would guess not knowing this about positive standards, and probably any tech that tried to help while in the car, just would never get it right.

When mixing early and late models I would think you would have to reverse hook up one set so the speakers pushed at the same time. Is that correct?

Thanks for all the help

Mark

[DavidF]

...Now back to Bill Chase , screaming trumpets poorly recorded on vinyl then copied to CD but no fatigue when listening now a days.:p


Wow, I have not heard that name for many years, Bill Chase. His band was problably the first pro concert I ever saw live. Some local high school auditorium. Yes, he was a screamer on the horn.

On the polarity thing, suggest you check the polarity on the lower mid from the cabinet terminals. Whatever that polarity is, put the woofers in opposite polarity.

DavidF

[Zilch]

When mixing early and late models I would think you would have to reverse hook up one set so the speakers pushed at the same time. Is that correct?Well, sorta.

Most common problem comes from mixing vintage JBL with systems from different manufacturers in, for example, home theater systems. They must all be checked for polarity and wired correctly for proper phasing.

I never know a sub's polarity until I check it.

[Then I forget, of course.... :p ]

[opimax]

On my sub I have a remote which has 90 degree phase shift adjustment. It seems to be best at 0 shift positive still is positive although it has RCA out to it, can't actually chage wiringing per se. Also the receiver has a 180 shift choice and it to is consistant and sounds best on "normal".

The centrer channel is different. I have a KEF XT2c something or other, expensive :) current model. i am not sure what initial recommendation would be for this would be. Currently it is hooked up w/pos to pos.

If I were to hook up this center channel as my left and a 120TI as my right in an old analog stereo, no processing, etc what is recommened way?

Both pos to pos or invert one so woofers move out together? and lastly if inverting one would it matter which speaker to change?

I am going to swap center at the reciever and listen back and forth to test

Mark

[Zilch]

Both left and right, the woofers should move in phase together.

I'd say center channel should be in phase with them both, yes.

I'm not a HT expert; somebody else can tell you more better about centers, surrounds, and rears, most likely....