WOPL running 4 Ohm speakers

FredR said:
Could be a safe operating area (SOA) issue. Exact issue I encountered. On all my WOPLs I've disabled that protection so I can drive 2 ohm speakers. No problem since. Most don't recommend that balls to the wall approach. Fuse protection is still there. Ask Joe about it.

Fan required.
Click to expand...
Does anyone here know how to remove this? Joe if you are around can you please explain.
 
Myself, not a clue on how to remove it. Joe should have some suggestions on resolving your issue without removing it, I would think.
My 4 ohm stereo subs are single driver Dayton Audio 15" Ultimax in the recommended precut flatpack cabinets from Parts express with no internal crossover. A active MiniDsp 2x4 crossover feeds two WOPLS. One for the stereo subs, one for big stereo JBL Millenniums. Never a issue like you've described.
I did see one issue in your wiring if I remember correctly. Think you had the flying yellow output wires from the backplanes to the DCP zip tied to adjacent wiring.
This is error, think about it. All that AC signal output is in those wires is being inducted into adjacent wiring. Those need to be kept as far away from other components as possible and fly between the points. Sending this then I'll look for a 400 photo.
 
George S. said:
Myself, not a clue on how to remove it. Joe should have some suggestions on resolving your issue without removing it, I would think.
My 4 ohm stereo subs are single driver Dayton Audio 15" Ultimax in the recommended precut flatpack cabinets from Parts express with no internal crossover. A active MiniDsp 2x4 crossover feeds two WOPLS. One for the stereo subs, one for big stereo JBL Millenniums. Never a issue like you've described.
I did see one issue in your wiring if I remember correctly. Think you had the flying yellow output wires from the backplanes to the DCP zip tied to adjacent wiring.
This is error, think about it. All that AC signal output is in those wires is being inducted into adjacent wiring. Those need to be kept as far away from other components as possible and fly between the points. Sending this then I'll look for a 400 photo.
Click to expand...
Thanks I will separate the wires.
 
Yellow wires on a 700, you get the idea. Old photo, the meter signal wires were later moved to the DCP, the copper RCA plate reinstalled, Joe's continuous improvement ground mod, and other things.
 

Attachments

  • PXL_20220103_013712761.jpg
    PXL_20220103_013712761.jpg
    3.3 MB · Views: 25
Last edited:
FredR said:
Could be a safe operating area (SOA) issue. Exact issue I encountered. On all my WOPLs I've disabled that protection so I can drive 2 ohm speakers. No problem since. Most don't recommend that balls to the wall approach. Fuse protection is still there. Ask Joe about it.
Fan required.
Click to expand...
I also been running my Amp into Lower ohm speakers (impedance I have not tested yet) and they sounded great until I turn them up loud (w more bass it happens at lower Volume) than I get a ripping sound thought the Tweeter , is that what you had? before disconnected the protection circuit?
 
plex said:
4.1 ohms View attachment 68284
Click to expand...
Joe found that Gene had the Mica capacitors that were pushed to far into the Control Boards , The Mica capacitors from the factory had crud on them which leak down the leads and could also leak when heated up which could cause a bad solder joint. Gene found one open (I also install mine pushed into the board to far I was suppose to stand them up w a Gap) Gene do you remember which one it was? this will cause noise problem and spikes sounds (they are used for preventing High Fhz noise ,,,,,, and more related to this) I see your are also install pushed in?
 
MusicSteve said:
Joe found that Gene had the Mica capacitors that were pushed to far into the Control Boards , The Mica capacitors from the factory had crud on them which leak down the leads and could also leak when heated up which could cause a bad solder joint. Gene found one open (I also install mine pushed into the board to far I was suppose to stand them up w a Gap) Gene do you remember which one it was? this will cause noise problem and spikes sounds (they are used for preventing High Fhz noise ,,,,,, and more related to this) I see your are also install pushed in?
Click to expand...
no...i really dont remember ... i tested all through the traces and found some things i did not like ..i cleaned the legs and resoldered...it worked...
 
May have missed it, but have you tried it with the equalizer out of the system completely?
Those equalizers are well past due for a recap.
After seeing the photo, I understand why you want to use the Bose.
 
George S. said:
May have missed it, but have you tried it with the equalizer out of the system completely?
Those equalizers are well past due for a recap.
After seeing the photo, I understand why you want to use the Bose.
Click to expand...
The EQ has been serviced and is running better than new. I also ran the system without EQ same thing. Thanks for all your help.
 
The VI limiter works as designed. I snub the 4 ohm condition at about the same watts out as 8 ohms for thermal reasons (PL let you blow your amp up if you wanted, I am trying to avoid that). The PL400/700 are not thermally designed to handle CW output at 4 ohms. You are aware of that.



The VI limiter will work anywhere along the linear spectrum when you are driving a load. When you hit around 42.5V peak into a 4 ohm load, you will begin to activate the VI limiter and the signal will flat top limiting the current into the load. That is exactly where you were at 30.05Vrms into your 4 ohm load (10.6A!!). A VI limiter responds to both the voltage and current that is going into the load. The simple spice model I sent you should help explain that, it is truly linear in nature and will protect anywhere along the signal spectrum that it needs to.
 
Yes the positive and negative halves of the waveforms work identically within the tolerance of the Vbe of the MPS651/751 devices.



Lifting one end of either or both of D13L/R or D14L/R diodes will be necessary to disable the VI protection. There are other methods but are far more invasive. You only need to lift one diode to satisfy your curiosity.



Removing the wire from Pin 4 and 8 may seem the obvious way to disable but the circuit relies on the shunting of the 0.33 ohm resistor between those pins and the output terminal Pin 6 for proper operation of the VI limiter. If you lift them, the bias from R23, 24, 29 and 30L/R will take over and pretty much shut everything down.
 
I am not exactly clear. Is it one or both of the diodes that we must remove?
 
You must log in or register to reply here.
Back
Top