Gibsonian's Cherry Pl 700 Ser I, soon to be a PLWO-1000

[ksrigg]

I know Lee said my PLWO 1000 was throwing 525 watts at clipping, so probably in the 500 watt per channel neighborhood, unless the waveforms start to compress, or if you are talking about speaker DRIVERS starting to compress...Past the first 200-30 watts I don't see how you could discern any compression other than your freaking eardrums nearing the rupture point...Maybe it's eardrum compression.....

 

[laatsch55]

As you likely know the drivers begin to compress the waveform well before their max output. With the power you are throwing at these drivers, the compression that is occurring is part driver compression for sure. Any idea of the wattage or voltage you are throwing at them when you are maxing them out?

That's just it, I don't think I have maxed em out. Doesn't sund like it anyway. Voltage??? jeez, I'll hook up the Fluke and catch some readings. The 2" DCM 50 drivers did not come with that info. I'll have to see if I can dig it up.

 

[laatsch55]

Sutton----very good point.

 

[Gibsonian]

Here's part of a JBL 15" driver spec sheet. As you can see, compression starts well below rated power. So if you are pushing your drivers, you are most definitely hearing compression of audio signal from them. What is the rated power handling of your speakers? If it is well under the 525 watts of the PLWO, you have a fair amount of compression. Not clipping but compression.

Specifications:
Nominal Diameter: 380 mm (15 in)
Rated Impedance: 4 ohms (G)
8 ohms (H)
16 ohms (J)
Power Capacity1: 600 W AES continuous pink noise
Sensitivity 2: 97 dB SPL, 1 W, 1 m (3.3 ft)
Frequency Range3: 30 Hz 2.5 kHz
Power Compression4:
at - 10 dB power (60 W): 0.7 dB
at - 3 dB power (300 W): 2.5 dB
at rated power (600 W): 4.6 dB

 

[laatsch55]

That's starting to make sense. Nakdoc mentioned once that some distortion on the horns is the air in the throat section gettin tore the F%$# up. I did not realize a speaker could comporess. I thought they went from full excursion to exploded voice coil.

 

[laatsch55]

Finally got some time off, back to amp building. Populating some bnoards today.

 

[Gepetto]

Nice parts organization Lee, looks like you have it down to a science.

 

[laatsch55]

Nice parts organization Lee, looks like you have it down to a science.

Thanks Joe. Those little bins have "latched" covers for each compartment, so you can dump one compartment and not dump the rest. After getting an order, as I check for getting everything, OI'll get the lead bender and put em away as I go through the parts.
I also print off a fresh BOM and as a value of components is mounted and soldered it gets a check through the listing. Really helps as I sometimes have to drop everything and run. Less confusion when I get back to it.

 

[laatsch55]

Resistors and diodes in.

 

[laatsch55]

Everything but the big caps.

 

[laatsch55]

Complete with big caps.

 

[laatsch55]

Ready to go. Complete with the "Gepetto" special on the back of the board.

 

[speakerman1]

And your point would be? LOL

Larry

 

[Gibsonian]

That sweet looking board is getting me a bit excited, for sure. The Gepetto special is the thump eliminator, right?

 

[laatsch55]

That sweet looking board is getting me a bit excited, for sure. The Gepetto special is the thump eliminator, right?

Not only that Scott but also eliminates the tendency to "latch up" the positive rail on power up. During the unstable power up sometimes a PL amp would latch up and send all positive rail voltage to the spoeaker outputs. PL tried to address this problem but didn't eliminate it or didn't totally understand it. The new bnoards also eliminate any chance for high frequency oscillation, hence the recommendation for putting in the MJ 15024, MJ21194, or, 96 output combinations.

 

[laatsch55]

And your point would be? LOL

Larry

Photograpic evidence of progress, of which, there hasn't been a whole lot of lately!!!!!!!!!!!!!!

 

[laatsch55]

DC protect boards soldered up and ready to go.

 

[laatsch55]

Robbed the old "Media Sound" Series one of it's "Anti-Hum" plate. The tape with repair notes was still on the backside of the faceplate. Media Sound was a small independent studio in Southern California. I bought this from the owner when he closed up shop and moved to Missouri, Minnesota, where ever the hell it was.

 

[laatsch55]

After having two failures of the stock 25 amp bridge rectifiers it appears the additional inrush and load demands are too much for the stock BR. It will now be standard procedure to upgrade to a 35 amp unit.

 

[jbeckva]

After having two failures of the stock 25 amp bridge rectifiers it appears the additional inrush and load demands are too much for the stock BR. It will now be standard procedure to upgrade to a 35 amp unit.

Hmmmm..

Gimme a part number and source for mine, or ya can just send it with the protect pcb's when you get 'em straight. Can never have too much current carrying capability, eh?