JBL Performance Series

[bonosurf]

I used to work for a company that did certification testing on consumer and pro audio systems. They did work on the Performance series and I ended up with a prototype PC600 system. I recently took the system out of storage and found an issue with MF driver. By applying light pressure to the diaphragm you could feel/hear a "crunch" in the VC/gap. The VC DC resistance was in spec and an impedance sweep of the driver showed that there was some obstruction in the gap. I removed the surround, diaphragm and VC to find massive amounts of material in the gap. The VC was pristine. Looking at the residue under a microscope it appears that the plating on the pole structure as corroded and fallen into the gap. This appears to be an issue since this loudspeaker system was only exposed to home/office level humidity (average nothern california indoor environment).

[rpatt]

I used to work for a company that did certification testing on consumer and pro audio systems. They did work on the Performance series and I ended up with a prototype PC600 system. I recently took the system out of storage and found an issue with MF driver. By applying light pressure to the diaphragm you could feel/hear a "crunch" in the VC/gap. The VC DC resistance was in spec and an impedance sweep of the driver showed that there was some obstruction in the gap. I removed the surround, diaphragm and VC to find massive amounts of material in the gap. The VC was pristine. Looking at the residue under a microscope it appears that the plating on the pole structure as corroded and fallen into the gap. This appears to be an issue since this loudspeaker system was only exposed to home/office level humidity (average nothern california indoor environment).

You mentioned that this was a prototype. I wonder if the production models are made of the same materials as I have never heard of this problem.

[Dylanl]

Can someone help me with my 2 PS1400s and trying to match the output exactly. How would that be done? spl meter while adjusting the gain on the back?

LF crossover set to normal, seems if the LF level is set the same on both one is slightly louder than the other. These dials are not calibrated to one another.

suggestions please, thank u

[jblsound]

Can someone help me with my 2 PS1400s and trying to match the output exactly. How would that be done? spl meter while adjusting the gain on the back?

LF crossover set to normal, seems if the LF level is set the same on both one is slightly louder than the other. These dials are not calibrated to one another.

suggestions please, thank u

Could be the room. I would turn off one sub, run the pink noise through the other, check the spl from the LP.
Then turn off that sub and turn the other on. Repeat the signal through the second sub and adjust so its at the same spl as the first.

[rdgrimes]

Mine measure close to 5db different purely because of the room placement. There's only so much you can do about that. This is why we have AVRs and processors with PEQ and level adjustment. If you're running a simple stereo setup without the benefit of DSP, and no LFE input, be aware that only the "LF" knob effects the speaker level input. The "LFE" knob effects only the LFE input. There's also a difference in whether you are switched to "normal" or "separate" mode.

[Dylanl]

Yes I am running only 2 channel and switches set to LF crossover - normal, polarity - normal. I have only speaker wires running in from the amp. No LFE so, If I have the LF level set to full open throttle ( would be 5 on the dial) on both they should be both be receiving the full signal right? The only thing the dial does is back off from full right?

I just noticed one was set low and the other high. Some kid must have got back there and messed with it. Anyway now at wide open the bass is almost overpowering. I would still like to get them matched?

[rdgrimes]

Yes I am running only 2 channel and switches set to LF crossover - normal, polarity - normal. I have only speaker wires running in from the amp. No LFE so, If I have the LF level set to full open throttle ( would be 5 on the dial) on both they should be both be receiving the full signal right? The only thing the dial does is back off from full right?

I just noticed one was set low and the other high. Some kid must have got back there and messed with it. Anyway now at wide open the bass is almost overpowering. I would still like to get them matched?

Level settings are all relative. I'd start with them both at 12:00 and use them to get your desired response curve. That will be different for each one due to placement. With the crossover set to "normal" you are adjusting the octaves below 130Hz (rolled off up to 300Hz). Absent the ability to run a spectrum analyzer, I'd use pink noise and adjust them by ear one at a time. Once that's done I'd use the amp to adjust level L to R.

Here, they get a LOT of reinforcement from walls behind and at 1.5 ft from the wall they have a good 6-8db spike at 60Hz. Placed near a corner that can be more than 10db.

[Dylanl]

So wide open, turned full right does not make them equal? I would think it would from a signal standpoint, forget the room at this time.

I am wondering how everyone else that listens to 2 channel sets theirs up? I can't be the only one that has noticed this right?

measuring close to the cone then is best ?

[rdgrimes]

I think the point being made is that there's no such thing as "equal" unless you're measuring each in the same location. Use the balance control in your amp to adjust Lt - Rt. Use the LF control to get the response curve you want. (which could be different for each one)

There's no compelling reason to set the LF knob to max unless your response curve demands it. I have mine near to 12:00 and still get a big spike at 60Hz. If I was shooting for a very flat curve I'd have them lower than that. Absent any EQ you're going to be trading 30Hz levels for 60Hz levels, so do what sounds good to you.

If you have a burning interest in knowing for sure whether your 2 PS1400 are putting out the same levels, swap them L-R and see if you get the same results.

[Dylanl]

I just opened up my tweeters because they sounded a little different. Here's what I found, looks like two different tweeters. they measure the same with a meter, the 335663-001 is correct right? Can I get a replacement?

Thanks

[rdgrimes]

I just opened up my tweeters because they sounded a little different. Here's what I found, looks like two different tweeters. they measure the same with a meter, the 335663-001 is correct right? Can I get a replacement?

Thanks

Correct, looks like someone swapped in a different part. The best source for that tweeter is the S26, S38 and S310/312. Not the "ll" versions with grey cones, but the ones with copper cones.

[Dylanl]

I just checked my PC600 and it has the same odd tweeter. 050625. Are you sure this is not the tweeter that JBL used once they discontinued the 335663-001?

[rdgrimes]

I just checked my PC600 and it has the same odd tweeter. 050625. Are you sure this is not the tweeter that JBL used once they discontinued the 335663-001?

You'd have to check with JBL. All I can tell you is that 335663-001 is the part number listed by JBL in all the above speakers.

[rpatt]

I just checked my PC600 and it has the same odd tweeter. 050625. Are you sure this is not the tweeter that JBL used once they discontinued the 335663-001?

Yes that is the tweeter JBL used after the 335663-001. The problem I found with it is that it is jury-rigged together. I received one of my PT800's with the tweeter loose from the wave guide. I found that the tweeter dome was glued into the plastic frame then bolted to the wave guide. The tweeter dome was hanging from the wires inside the cabinet. I have since replaced all tweeters in my PT800's & PC600 with the original. They show up on e-bay or as mentioned can be taken from S26, S38, S310, S312. One other thing, the replacement tweeter uses small washers as spacers when bolting to the wave guide. The original does not need these.

[rdgrimes]

One other thing, the replacement tweeter uses small washers as spacers when bolting to the wave guide. The original does not need these.

Just to add to the confusion, some need the washers and some don't. The plastic ring on the front of the tweeter should be just flush with the wave guide. You may or may not need spacers to accomplish that properly. I took one out of an S38, where it had washers, and put it into a PT800 where it didn't need them.