nelsress begins his WOPL 400 project

[Gepetto]

View attachment Release notes for PL400 Light Board Rev_B.pdf

so, of the three, PAD 1, PAD 2, and PAD 3, is the red one right, the left one white and the black one to the ground, in the photo in your instructions? Sorry, I stripped the amp down months ago, guess I should have cut the wires in stead of de-soldering them!!!

Hi Nelson
Instructions attached.

 

[nelsress]

Outstanding!!

View attachment 19795

Hi Nelson
Instructions attached.

Thanks again Joe! Damn if I'm not a DC offset test and 5 solder connections away from a WOPL 400 amp of my own!!!

 

[nelsress]

Oh!!!

When plugged directly into the wall..what's the bias?

You mean without running through the variac!!! I don't know, I'll have to check and make sure it's the same or close. Thanks for the clarification, I wasn't thinking about the fact that I had a variable transformer between the amp and the wall! Thanks, I'll check that too.

 

[nelsress]

Alrighty then!!

I got 0.018 DC offset on both channels, that's not too high, is it? When plugged straight into the wall the bias only went down a little from 3.55 to 3.47 so I just nudged it back up to 3.55 for the hell of it. The LEDs are all working and it looks like I'm ready to apply a signal and a load to this baby!!! Any other tips/precautions before I do so? Thank you guys so much!!

 

[Gepetto]

I got 0.018 DC offset on both channels, that's not too high, is it? When plugged straight into the wall the bias only went down a little from 3.55 to 3.47 so I just nudged it back up to 3.55 for the hell of it. The LEDs are all working and it looks like I'm ready to apply a signal and a load to this baby!!! Any other tips/precautions before I do so? Thank you guys so much!!

No it is fine. The bias should have been a negative reading, not critical but that is what it usually is due to the front end configuration (NPN).

 

[nelsress]

A pic or two

I was so excited I closed it up before taking any shots of the LED light board and its connections but here are a couple of it powered on. Ain't she purty?

 

[nelsress]

My bad,

No it is fine. The bias should have been a negative reading, not critical but that is what it usually is due to the front end configuration (NPN).

it was a negative reading, sorry. I was just so excited I forgot to type the negative part!

 

[laatsch55]

Pretty good lookin carcass...

 

[nelsress]

Pretty good lookin carcass...

Once again, thanks to you Lee! Although, it's alive now, I don't know if carcass is a fitting term anymore.

 

[laatsch55]

No Nelson it certainly doesn't anymore , and you've certainly made it your's!!

 

[nelsress]

No Nelson it certainly doesn't anymore , and you've certainly made it your's!!

Grinnin' from ear to ear and got a few goose bumps crankin' Brothers in Arms as we speak. It's almost perfect-I forgot to adjust the meters so I've got to do that yet as they're a little off but I'll do that when I tear down the old rack and put everything in the new one this week. I can live with it until then. Thank you Lee, Joe, Doug, Don, Nav, Jason, and anybody I forgot! It sounds really, really good already and it's not broken in yet, and I'm only running it through my vintage Jensen drivers in Heathkit AE-40 cabinets (see last photo). Can't wait to hook up the ESS, Ohm Walsh and Infinities to this baby, I think I've got my system down pretty good now. The tube Dynaco PAS 4 seems to be a very good pre for this amp. I've gotta get back in the living room, Dire Straits sounds great but not as good a room away as it does in the sweet spot!! Who says an amp is an amp and they all sound the same!?!?

 

[laatsch55]

Pretty exciting huh?? Don't forget to monitor heatsink temps till ya get a feel for how warm it's going to run...

 

[nelsress]

Yep, sure is!

Pretty exciting huh?? Don't forget to monitor heatsink temps till ya get a feel for how warm it's going to run...

On my laptop in the living room now so I can listen and "talk". Lee, I'm assuming I check it by just touching them, avoiding those pesky, naked transistors?

 

[laatsch55]

Yes Nelson, just reach out and fondle those buggers....

 

[nelsress]

Sounds like fun

Yes Nelson, just reach out and fondle those buggers....

Maybe I can print out a pic of one of Nav's avatars and put it on the heatsinks! So far they're cool to the touch and it's perched on top of a tube preamp but I'm sure they'll heat up. These Jensens never sounded so good, amazing work Joe, I'm sorta speechless.

 

[nelsress]

This isn't going to sound even better with break in, is it? I don't know if I'm worthy of better sound. LOL This is me being speechless!

 

[Gepetto]

Maybe I can print out a pic of one of Nav's avatars and put it on the heatsinks! So far they're cool to the touch and it's perched on top of a tube preamp but I'm sure they'll heat up. These Jensens never sounded so good, amazing work Joe, I'm sorta speechless.

That is the reaction we work for Nelson...

 

[nelsress]

In between tracks there is a low level hum that isn't noticeable when the music's playing, will that diminish as it breaks in or is that normal? I'm not listening at what you would call low levels here. Not ear-bleeding but not low either, sort of a medium to high level. It is very low level and doesn't diminish the listening experience whatsoever, just wondering. This sounds freakin' awesome Mark Knopfler's guitar and vocals, the organ, the drums, amazing. The bass is just how I like it, there but not in the forefront, crisp and clean. Anyone thinking about either doing this or having it done-stop thinking about it!!!

 

[Gepetto]

In between tracks there is a low level hum that isn't noticeable when the music's playing, will that diminish as it breaks in or is that normal? I'm not listening at what you would call low levels here. Not ear-bleeding but not low either, sort of a medium to high level. It is very low level and doesn't diminish the listening experience whatsoever, just wondering. This sounds freakin' awesome Mark Knopfler's guitar and vocals, the organ, the drums, amazing. The bass is just how I like it, there but not in the forefront, crisp and clean. Anyone thinking about either doing this or having it done-stop thinking about it!!!

Make sure that isn't noise coming from the input source Nelson. A power amp will amplify any noise it is being fed, even hum.

If the noise exists with no input cables attached then you have to tackle it within the power amp. If it is there only when you have a source connected to it, then you have to tackle it within the source.

 

[laatsch55]

It should be a black hole for noise between tracks. Having your amp on top of your preamp may not be the right thing to do. The PL 's transformer throws a large magnetic field.