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WOPL dual 500
- Thread starter grapplesaw
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- Halfbiass...Electron Herder and Backass Woof
It's alive
Initial power on ok. Now have to rework the To-3 screws as they are shorting to to ground. I guess I am off to buy some nylon washers tomorrow someplace. The first build I let them flop about while I loaded the out put transistors and that was funky so want to improve that job setup.
It is a bit busy in there But it has like 50 miles less wire in it than original the build by PL. and no Ac wires bundled along with low and high voltage control and rail wires. I moved so much in this it's hard to say it is even a PL design anymore.
The control board will be about 2" above the output transistors. I have added a few extra rail caps similar to Joe's design.
I have left off the fly back diodes as per the original factory built full complimentary amps I have.
I have left off all the ferric beads. I want to find out if they are required when running Joe's setup
Initial power on ok. Now have to rework the To-3 screws as they are shorting to to ground. I guess I am off to buy some nylon washers tomorrow someplace. The first build I let them flop about while I loaded the out put transistors and that was funky so want to improve that job setup.
It is a bit busy in there But it has like 50 miles less wire in it than original the build by PL. and no Ac wires bundled along with low and high voltage control and rail wires. I moved so much in this it's hard to say it is even a PL design anymore.
The control board will be about 2" above the output transistors. I have added a few extra rail caps similar to Joe's design.
I have left off the fly back diodes as per the original factory built full complimentary amps I have.
I have left off all the ferric beads. I want to find out if they are required when running Joe's setup
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The first one I built has three ferric beads per rail. The full comp PL 700 have one per rail and a quassi only has one on the positive rail. The WOPL setup has none. I put one per rail on the C-500 build only to be safe. I have not idea if they are needed.
Lee when I blew up a few drivers on the quassi dual 500 while driving in the 10-40 k area with about one watt power I did not see any parasitic distortion but the amplitude looked to be rolling off as it went higher with all thoughts beads in there. I need to revisit this area of inquiry. Got to set up a higher range on the Sectrum Analizer I have on the computer to observe it better.
Lee when I blew up a few drivers on the quassi dual 500 while driving in the 10-40 k area with about one watt power I did not see any parasitic distortion but the amplitude looked to be rolling off as it went higher with all thoughts beads in there. I need to revisit this area of inquiry. Got to set up a higher range on the Sectrum Analizer I have on the computer to observe it better.
- Joined
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- Halfbiass...Electron Herder and Backass Woof
- Joined
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- Halfbiass...Electron Herder and Backass Woof
They are there to prevent external inductive kick from exceeding the rail voltages and thereby exceeding the Vce of the output devices. It is not unusual to get many hundreds of volts inductive kickback if you develop an intermittent connection of your long wires to your speakers that the amp is pumping current into at the time. Most woofers in your speakers have an in line inductor in the crossover that add to the inductance of your speaker wire.
While in normal operation, these flyback diodes do nothing. But in the event of abnormal operation as described above, you will be glad they are in there.
PS: Don't cheap out, put them in...
While in normal operation, these flyback diodes do nothing. But in the event of abnormal operation as described above, you will be glad they are in there.
PS: Don't cheap out, put them in...
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I would like to clarify......
I posted a reply to this subject many years ago on the internet:
I spoke to Dean about the flyback diodes (D107 and D108) last night used in the Phase Linear 700 series II amplifier. He also concurred with me in that they were never used in the either the 400 II or 700 II fully comp output amplifiers and most schematics have errors.
(NOTE:The schematics referred to here were the 400 II and 700 II fully comp amplifier schematics and PRO700 schematic which show flyback diodes. Whereas none of the fully comp amps actually had them installed in them. There were other errors as well.)
As to why they were removed.... "probably because they were really not needed in the first place or were of little value".
(NOTE: It was Dean who said this not I. Only someone like Terry Pennington and Mike Frost might know why they were removed and Mike recently passed away.)
With regard to the flyback diodes; I have never suggested that anyone do anything other than what was factory approved or factory practice.
I am not an electrical engineer. Nor do I try to pass myself of as one.
Ed
I posted a reply to this subject many years ago on the internet:
I spoke to Dean about the flyback diodes (D107 and D108) last night used in the Phase Linear 700 series II amplifier. He also concurred with me in that they were never used in the either the 400 II or 700 II fully comp output amplifiers and most schematics have errors.
(NOTE:The schematics referred to here were the 400 II and 700 II fully comp amplifier schematics and PRO700 schematic which show flyback diodes. Whereas none of the fully comp amps actually had them installed in them. There were other errors as well.)
As to why they were removed.... "probably because they were really not needed in the first place or were of little value".
(NOTE: It was Dean who said this not I. Only someone like Terry Pennington and Mike Frost might know why they were removed and Mike recently passed away.)
With regard to the flyback diodes; I have never suggested that anyone do anything other than what was factory approved or factory practice.
I am not an electrical engineer. Nor do I try to pass myself of as one.
Ed
- Joined
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- Halfbiass...Electron Herder and Backass Woof
- Joined
- Jan 14, 2011
- Messages
- 74,984
- Location
- Gillette, Wyo.
- Tagline
- Halfbiass...Electron Herder and Backass Woof
It's alive
With Joe's advice I have added the fly back diodes.
the job is finished. Time for testing it out. All transistors are bolted tight,soldered in. I have run a small signal with DBT light powering it. It has a nice sine wave both channels. I will heat it up to full rail voltage next then see what the AP tells me.
With Joe's advice I have added the fly back diodes.
the job is finished. Time for testing it out. All transistors are bolted tight,soldered in. I have run a small signal with DBT light powering it. It has a nice sine wave both channels. I will heat it up to full rail voltage next then see what the AP tells me.
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