Jer's PLWO to be... (Jer vs the 700, Round 2... it's "Personal" this time)

[jbeckva]

19K, 2V/Div

 

[jbeckva]

Ah OK...

Forgot I still had a "reference" here in my possession - Lee's "Loaner"!

Yeah.. it actually is less linear than mine. Alrighty then!! Guess it's time to start making those new meter LED strips and be done... heheh. Thanks Joe for the clarification, appreciate it!

 

[Gepetto]

I will soon be providing some optimization for the back end portion of the amp as well Jer. It is acceptable and specs out that way when distortion analysis is done. Recall that the THD specs are done at full output power, where this artifact is much less noticeable.

This artifact will get worse at very low levels.

The amp transitions from running on only the predrivers at low levels to kicking in the main outputs above that. The amps effective output impedance changes from 10 ohms (dictated by R38/39) to nearly zero after that switchover occurs. Thus an 8 ohm load is significant when compared to the 10 ohms of R38/39

 

[jbeckva]

Let there be.. more light! Getting there.. now need to do the other meter..

 

[Gepetto]

Do you have the rectifier, filter caps and ballast resistors on the flip side of that board Jer?

 

[jbeckva]

Do you have the rectifier, filter caps and ballast resistors on the flip side of that board Jer?

The resistors are on the flip sides of the boards. The bridge and filter cap is on the main terminal strip near the transformer. 1.4A bridge with 470 uF ought to do it...

 

[Gepetto]

Good deal Jer, that should cover it. Some of the replacement guys on Ebay just use the LEDs with only a ballast resistor and no rectifier/filter which ends up with annoying 60Hz flicker and back bias on LEDs (which they do not like).

 

[laatsch55]

Joe, thanks for explaining this crossover artifact we are seeing here. That helps.

 

[jbeckva]

Ok.. dumb question time... I think I need to put those caps back for the Z network, no???

(awaiting answer.. and whomp upside head... )

Sounds like.. errrr... big pile of yanno what right now...

 

[laatsch55]

Yep....

 

[jbeckva]

Alright well.. turns out the caps unfortunately succumbed to NON non-destructive removal.

So I figured it also would be a good time to do the DCP "right" with those binding posts and standoffs. I have part numbers for the posts themselves, but what about the standoffs?

 

[jbeckva]

Found the standoffs and whatnot.. "Awaiting Parts" (bummer)

 

[laatsch55]

Does the DCP have the small white styrene caps??

 

[jbeckva]

Yep, got 'em on order too. Should come in a couple of days - Mouser's pretty good there.

 

[Ken.nelson0317]

Very interesting reading here. I hope to try this someday myself. Lots of learing to do first.

 

[jbeckva]

Very interesting reading here. I hope to try this someday myself. Lots of learing to do first.

Keep eyes peeled for those on 'dabay that are blown.. inop.. cords cut.. whatever. Then nab one and dig in a bit... but as I've learned so far.. don't replace the bloomin' TO3 sockets unless you REALLY REALLY have to (or you got 'em figured out all the way, one of the two heheh).

Ahh.. looks like the mouser shipment will come in by Weds. I have a day or two off to relax. Got the "Yammy with Balls" hooked up for now - figured I better or I might not let "Lee's Loaner" free..

 

[laatsch55]

Yep, got 'em on order too. Should come in a couple of days - Mouser's pretty good there.

Jer for some reason I thought the DCP cap was contributing to the crossover notch. I replaced it with a .1/250 volt polypro film. Could be just me but I thought the notch improved and it sounded better.

 

[jbeckva]

Jer for some reason I thought the DCP cap was contributing to the crossover notch. I replaced it with a .1/250 volt polypro film. Could be just me but I thought the notch improved and it sounded better.

That's cool. Yeah, what I have on order are Wima .1/100 volts polypro's.. lil less in the "volts" department, but I don't see me rarely going close to the 62.5 volts I did measure the amp at before. Just too.. much.. SPL with these CV's being rated at 106!

We'll see in a couple of days how they make 'er sound. I guess these "Z" networks are common in a lot of amps, now that I've been educated in 'em. I see how other amps do it in series with an inductor too. Hmmm... all fascinating stuff!

 

[Gepetto]

The series inductor is there for a different purpose Jer. A long story.

 

[jbeckva]

So ok.. got the DCP in.. had to scrounge a little bit for the screws..

and then... )(*&_)(*&(*^()*^&^()*^& grrrrrr damnitalltohell!!!

I knew if I wasn't careful with me "lobster craws" rummaging about that those Q4's on the WO board were taking a beating. Just bent one.. ONE time too many...

MPS92A's? I think? Joe n Lee.. where do I need to get them? But heck while I"m thinking here... I noticed that you guys put tis97's in on some, mps's on the others.. hmm.. which is "best"?

Do I need to match them too??

(dagnabit.. awaiting parts.. AGAIN.. )