The Phase Linear 400 Guinea Pig

[laatsch55]

Let's see, operations inside the brackets first...

This could be fun. If we can compute the power radiated by the outputs, and add it to the power produced by the amplifier, we could come up with a figure of merit or an efficiency rating for the PL amps because we know (or we can measure) the power going in. I wonder if that has ever been done?

Maybe this is a thesis topic...

I have a pretty good instrument to do that with.

 

[laatsch55]

Adding another 1/2 inch will pick up another 8% radiation efficiency compared to the stock heatsink area.

Joe, in the grand scheme of things, is getting the heat away faster and more efficiently just a pursuit of diminishing returns?? Or are there valid and significant audio related benefits?? I understand the process, what are the not so noticeable benefits?

 

[laatsch55]

Damn, got two threads where this info should be posted. I'm going to load up the 400 at 4 ohms, about 70 watts power, no fan anmd see if the thermoswitch will open.

 

[wattsabundant]

Well an AB amp does anyway. that's why I was around 100. Dropping to a four ohm load would have helped a bunch too. When they failed did they go short or open??

Just the one I loosed shorted. No other damage.

 

[wattsabundant]

Power input is not just Volts x RMS amps. You have to know the power factor to calculate input power in watts. A power meter will save the trouble of the calculations.

 

[laatsch55]

Ah yes Don, forgot about the power factor. Nice catch.

 

[Gibsonian]

1/3 power at 4 ohms on a 400 will be higher than at 8 ohms. Maybe 165 watts.

 

[laatsch55]

Couldn't get past 50 watts without taking out the 5 amp rail fuses. And that was plenty to heat it up enough to know copper without a fan wasn't going to do it either.

 

[kevin]

THIS new Forum is BAD ASS !!!

 

[laatsch55]

Tell Jer thanks, all his doins.

 

[kevin]

Hey Jer..... Thanks man !!!! Just an unreal job ya did here. Very easy on the eyes. Love the colors !!!!

 

[Gibsonian]

Hey Jer..... Thanks man !!!! Just an unreal job ya did here. Very easy on the eyes. Love the colors !!!!

Yes, we're right up town now. Fine job.

 

[jbeckva]

Hey Jer..... Thanks man !!!! Just an unreal job ya did here. Very easy on the eyes. Love the colors !!!!

Lot easier to see, eh? You betcha.

 

[laatsch55]

The guinea pig is fixin to start living life as a "Loaner". Beins the "Cabbage Case " is making a trip down anyway , hell send a loaner!!!!!
Don't have time to put a Joe board in, BUT, did replace Q1,2,3,4,5,7,10, All electros, even went 470 on C6 with the anti-latchup "Gepetto mod. It's getting some Ed Blackwood "goody box" 18,700 CD caps. I'd hate to send a loaner without DC protect so it gets that, MJ 21194's as outputs with RCA-410 as drivers.

Also--- KUDOS TO NavLinear---DUDE!!! The faceplate holder is TITS!!!

 

[laatsch55]

Progress.....

 

[NavLinear]

This amp will be a nice loaner - just the coolness of the heat sinks alone make it a one-of-a-kind! It looks like you've installed some new power supply caps, Don's DC protect board and it seems you swaped out the electrolitics on the controller board. Glad its going to a new member - me thinks he'll like it.

I'm glad the faceplate holder is working out. I have a 700 faceplate holder sitting on my desk that I'll get out to you in the near future. I do have a package that you should be seeing this week sometime. I sent out the three revisions of the bias transistor bracket as the third rev came out today. I'm curious which one you'll like the most. All should work out fine but I do have my favorite.

 

[laatsch55]

Ed Blackwood was mentioning reading about the Bias bracket and was fairly impressed with em, so as soon as some get here I'll send some on. he liked em--a lot!~. Now the faceplate holder, it will probably go to Ed also, if ya wouldn't mind makin another.....

 

[laatsch55]

Now this little B*&^% gave me a run for my money too. Several gremlins running around this one. Couple bad diodes, Replaced all the input transistors ( 6 times) Yep, that's 48 transistors. Finally got the left channel to come around with just 5MV DC offset. Right channel was a F&^%$#* Battle that started at 79 volts DC offset and finally got it to 4,5 volts DC. Found a resistor out of spec by a magnitude of 10. R-16, a 33 ohm 1 watt was reading 330 ohms. Changed that out and it went right to 2,5 MV offset.

 

[Ken.nelson0317]

Cant wait to get the Guinea Pig and get My PL sent off to Lee. I am very excited. Kinda cool to see what the pig has gone through. Nice Avatar btw. Thanks Lee.

 

[laatsch55]

You're welcome Ken. Kind of a unique amp for sure. Some preliminary test results....

Ken , it won't make ity out today. Tomorrow morning.