WOPL running 4 Ohm speakers

[plex]

Hello everyone I am getting distortion(clipping) when running 4 ohm speakers on the WOPL400. It's happening when I play it loud or increase the bass. I ran it with 8 0hm and played it loud had no distortion but it did stop playing and I had to reset the power. Okay before anybody says I should be running 8 ohm let me say that the PL400 has been running 4 ohm for 50 years without a problem. I have blown a fuse(8 AGX) maybe like twice when driving it extremely Loud back in the 90s when I acquired the system. My speakers setup is 2 Pairs of Bose901 series1 connected parallel. PL400 has been a true workhorse Im hoping that this problem is just a simple fix.

 

[George S.]

What are the output meters showing when it clips? My 700 Pro WOPL drives 4 ohm stereo subs to brutal sound pressures with no issues.

 

[George S.]

Oh, and before I built the 700, a 400 WOPL did the same.

 

[plex]

Oh, and before I built the 700, a 400 WOPL did the same.

I wanna say around 100 maybe bonucing around the red. Now the left meter looks like it's stuck at 30. The right meter has not worked for a very long time, it was dropped on the right side one day when the amp was moved. How come running a stock PL400 at 4 ohm produced no clipping?

 

[WOPL Sniffer]

are you using a fan on the back?

 

[plex]

are you using a fan on the back?

No. Should I? I never have.

 

[WOPL Sniffer]

No. Should I? I never have.

The book says use fan

 

[WOPL Sniffer]

If your thermal switch set, thats a good indicator you need a fan.

 

[WOPL Sniffer]

4 fin or 8???

 

[WOPL Sniffer]

who WOPL'd it?

 

[plex]

Okay I can put a fan. But the clipping is happening as soon as the volume is turned up not even hot yet.

 

[plex]

4 fin or 8???

4 fin

 

[WOPL Sniffer]

4 fin

So you have about half the cooling area as an 8 fin. We ALWAYS recommend NOT doing a 4 fin................................

 

[plex]

who WOPL'd it?

My son and I. Newbies not pros.

 

[WOPL Sniffer]

Get an 8 fin to do.

 

[plex]

So you have about half the cooling area as an 8 fin. We ALWAYS recommend NOT doing a 4 fin................................

I understand about the cooling 4 fin vs 8 fin. But clipping is happening right away.

 

[WOPL Sniffer]

With the added performance a WOPL brings out, it also brings out a lot of heat. 4 fins is riding the fence on cooling. Put a fan to it

 

[WOPL Sniffer]

You may have something wired wrong or maybe your bias is incorrect. What did you NOT replace when you WOPL'd it??? Are all the outputs new? New back planes? New control board? Maybe post some pics... Something is wrong with your build. Joes directions say the builds are VERY ADVANCED and many beginners have had problems. 1 cold solder joint could do it. If you had a tech build it, you would have recourse.

 

[WOPL Sniffer]

did you try a different preamp? Your pre may be doing it.

 

[plex]

We replaced everything except for the meters, transformer, and rectifier. Also I set and checked the bias exactly as the instructions said.