Bob's 4 WOPL 400 builds

[audiobob]

The DC protect will sometimes nuisance trip if a lot of low end material is played at high volume. Also check rail fuses. To reset the DC protect board cycle ac power.

So cycling the power did reset it. Was listening at an even lower volume ( maybe 25% volume ) last night and it did it again after about an hour. Cycled power and no problem with for the last 3 hours of play at a little more volume than that. Is there maybe a mod for the DC Protect board? I know its not the amp because both channels are still outputing music, just no sound out of DCP board. May swap that board out tonight if I have enough umpf after work.

 

[audiobob]

Awesome workmanship Bob. You are a master builder!

Thanks Fred.

 

[laatsch55]

You can play with the kick threshold by varying the value of one of the small electros. You have to talk to Don to figure out which one. Also...since those 123 IC'S a r e made by China now so you might have a bad IC.

 

[audiobob]

Very pretty work Bob, looks like you have done this before. Glad you made it through the last steps and got to listen to some music through the amp (for a while anyway )

I am sure you will find your way through the last issue, seems you have it narrowed down.

Thanks Joe. If those who have a good ear for audio but haven't heard a WOPL could hear one, I think there would be a real scramble to get there hands on one. Very nice!

 

[audiobob]

Interesting looking heatsinks mounted on the TO-3 transistor cans. I've never seen those before but I have numerous TO-5 / TO-39 + other can mounting heat sinks in stock at home.

I looked at a few and finally decided on this one. It's made by Aavid Thermalloy 579103B00000G ( Digi-Key # HS236-ND). My other 3 PL400s don't have the extra fins so I'm hoping these will comp for that. Just an extra precaution. I may want to drive them a lot harder in the future.
[h=2][/h]

 

[audiobob]

You can play with the kick threshold by varying the value of one of the small electros. You have to talk to Don to figure out which one. Also...since those 123 IC'S a r e made by China now so you might have a bad IC.

Thanks Lee. I'll probably talk to Don about it and see what he thinks.

 

[laatsch55]

Welcome Sir. When you can get 20hz program material through it that will tell you. You now have an amp that is essentially flat to 10hz.