Skynyrd77's Thank Godamighty , Finally My Own WOPL Build Thread!!

Skynyrd77

Skynyrd77

Veteran and General Yakker
#82
Joined
Jan 12, 2014
Messages
3,971
Location
Mill creek Indiana
Tagline
lost in my own world
#82
laatsch55 said:
It's damn noisy, residual is 465 microvolts on one and 2.6 MILLIVOLTS on the other. THD & N is good, Signal to noise ratio is 30db on one channel and 80 on the other... 2.6 millivolts is a TON of residual noise, should have ben able to hear that buzz for a mile...
Click to expand...
You got to realize it got no kind of true listening lol. I was happy as hell cosmetically and scRed of it at same time lol. I don't remember a buzz but I'm sure I had one at the time. So I know it looks nice lmao
 
Gepetto

Gepetto

Administrator
Staff member
#83
Joined
May 15, 2011
Messages
14,215
Location
Sterling, MA
Tagline
Old 'Arn Enthusiast
#83
CASSETTE DECK said:
The protection circuit limits current X voltage = power dissipation in the power transistors.

It's similar to a power supply protection circuit that I discovered by accident a long time ago that measures the voltage X current in the transistor, but the difference is that this amplifier protection circuit measures the voltage X current in the load instead. This means that the operation of the amplifier protection circuit is not affected by relatively minor fluctuations in power supply voltage.
The amplifier protection circuit automatically reduces the current limit if there is too little voltage across the load, caused by the load resistance or impedance being too low.
It's operation much more similar to a power supply foldback current limiting circuit.
Click to expand...
Correct, SOA protection is a function of the product of the Collector-Emitter voltage across the transistor and the collector current through it. The circuit involved takes both into account in determining if it needs to clip or not.
 
Gepetto

Gepetto

Administrator
Staff member
#85
Joined
May 15, 2011
Messages
14,215
Location
Sterling, MA
Tagline
Old 'Arn Enthusiast
#85
laatsch55 said:
At 4 oms loads, it clips at 55volts....that equals 14 amps of current.....
At 8 ohms load it clips at 63 volts....that equals 8 amps current.......

Things are not linear...so there is a voltage component to the protection circuit??
Click to expand...
And it is likely clipping in both cases from the influence of the protection circuit.
 
Skynyrd77

Skynyrd77

Veteran and General Yakker
#87
Joined
Jan 12, 2014
Messages
3,971
Location
Mill creek Indiana
Tagline
lost in my own world
#87
Gepetto said:
And it is likely clipping in both cases from the influence of the protection circuit.
Click to expand...
Wow. I think I might understand this a bit. Huh. I guess the word protection means to protect even if in doing so it screws up other stuff. Am I right? Or should I just stay out of it lol
 
laatsch55

laatsch55

Administrator,
Staff member
#88
Joined
Jan 14, 2011
Messages
75,252
Location
Gillette, Wyo.
Tagline
Halfbiass...Electron Herder and Backass Woof
#88
And pushing it further without blowing a fuse will just annihilate the output stage...
 
laatsch55

laatsch55

Administrator,
Staff member
#90
Joined
Jan 14, 2011
Messages
75,252
Location
Gillette, Wyo.
Tagline
Halfbiass...Electron Herder and Backass Woof
#90
Skynyrd77 said:
Wow. I think I might understand this a bit. Huh. I guess the word protection means to protect even if in doing so it screws up other stuff. Am I right? Or should I just stay out of it lol
Click to expand...
No , Jase in this case the board protection circuit shunts extra current away from the output transistors without hurting any components, it's desigh intent, up to a point...that coupled with the 5 amp rail fuses have serve it well since it was made. By putting in 10 amp rail fuses we have taken that option away...
 
laatsch55

laatsch55

Administrator,
Staff member
#91
Joined
Jan 14, 2011
Messages
75,252
Location
Gillette, Wyo.
Tagline
Halfbiass...Electron Herder and Backass Woof
#91
Meters isolated, i have effectively rendered D9 non-operational in the left channel....
 
Skynyrd77

Skynyrd77

Veteran and General Yakker
#93
Joined
Jan 12, 2014
Messages
3,971
Location
Mill creek Indiana
Tagline
lost in my own world
#93
Oh ok Ic . I forgot you basically took it out of normal operational mode when you put the big ass fuses in. I think I got it.
 
laatsch55

laatsch55

Administrator,
Staff member
#95
Joined
Jan 14, 2011
Messages
75,252
Location
Gillette, Wyo.
Tagline
Halfbiass...Electron Herder and Backass Woof
#95
That nagging question eh?? You funny Joe. Yeah, 4 amp compared to 16, jeez. Ok , one more question. On your board did you up the SOA for the better outputs of today?
 
laatsch55

laatsch55

Administrator,
Staff member
#96
Joined
Jan 14, 2011
Messages
75,252
Location
Gillette, Wyo.
Tagline
Halfbiass...Electron Herder and Backass Woof
#96
Changed Channekl 2 to AC and put it to monitor the left channel---the "unprotected" channel. Letting things cool off for a minute or twi then we'll have our answer....
 
Gepetto

Gepetto

Administrator
Staff member
#98
Joined
May 15, 2011
Messages
14,215
Location
Sterling, MA
Tagline
Old 'Arn Enthusiast
#98
laatsch55 said:
That nagging question eh?? You funny Joe. Yeah, 4 amp compared to 16, jeez. Ok , one more question. On your board did you up the SOA for the better outputs of today?
Click to expand...
Yes slightly Lee...remember these started out as aftermarket boards and there are many of them installed with the original PL909's in place. Can't go too crazy.
 
You must log in or register to reply here.
Top