Crazy things to do with a PL 3000 Preamp while we wait...

[jbeckva]

Since all the other projects are waiting parts at the moment, thought I'd do something with my own 3000 PL preamp. Since my number of sources are limited and most are already switched in and out of the signal path by way of my EQ, I'm looking to eliminate any "moving part" (like a relay) not directly needed for my application.....

So... as I'll need Phono1 and Aux, and be using the NR loop for the pre, this is the plan so far..

1. Eliminate K1, 3-6, 8-12, and 14 (missed that sneaky guy...)
2. Jumper the resulting sockets (NC contacts normally) for K's 8 through 12..

 

[Northwinds]

Cool! Eliminating relays means less can go wrong later down the road!

 

[laatsch55]

So, any testing yet??

 

[jbeckva]

Yep, all done... and it sounds phantasmagoric!! Basically for inputs the only two left are Aux and Phono1, while the EQ is in the processor loop - it has two tape loops so basically that's where my remaining inputs lie.

Ron's 400 should be a comin' soon... I will begin tearing just about everything outta it later...

 

[laatsch55]

Jer...Tracking number on the rest of Ron's goodies------962223115002214 Fed-Ex.

 

[laatsch55]

So basically you're a gain stage for 3 inputs??

 

[jbeckva]

Jer...Tracking number on the rest of Ron's goodies------962223115002214 Fed-Ex.

Damn reminded me!! I gotta get Richard's WOPL 1000 (the beastie) out in the mail TODAY... Just got it packed up, waiting to hear from him about sig req'd or not...

 

[laatsch55]

Ah, Richard D is about to be WOPL'd eh??

 

[jbeckva]

So basically you're a gain stage for 3 inputs??

2 where they'd normally be.... all "native" tape loops, filters, whatever had a relay "gone"... then up and down through the NR loop (usually jumpered on the back) and onto the vol/tone controls (defeatable) and finally the output amp...

pretty much.. yeah.

The other config this would work for would be if I substituted a dbx 200 or 400 program route selector for the EQ. I had one of those (hmm.. do I still.. gotta go look) but it did degrade things a lil.. to my ears, anyway...

 

[laatsch55]

Did it get the De-Oxit?? Are there electronics in there?

 

[jbeckva]

Did it get the De-Oxit?? Are there electronics in there?

Yep... still it was just a lil bit different through the dbx...

Not the 200... all switches there I believe.

 

[Richard D]

As of today I am...

Ah, Richard D is about to be WOPL'd eh??

 

[laatsch55]

Officially WOPL'd???

 

[jbeckva]

Taking a break (well .. multitasking sorta) from Ron's 400, now it's time to go see what I can do with these preamps (howdy Kev!!!). Came to the realization that the RCA4136's in my old one well... they're basically 4 741's, and although the 741 is an old famous workhorse when it comes to opamps, we probably can do better here...

SO.. my turn to do some brown dogging here... holy crap are them guys small! We're shooting for the LME49860's, and will put two of them on each adapter. Specs on the LME's...

Rail to Rail max - 44 volts
Typical THD - .00003 %
Typical Offset - .12 mV
Slew Rate - 20 volts/uSec

Time to try gluing a fly down, one leg at a time...

 

[laatsch55]

Missed a few specs there Lad, SNR, residual noise......

 

[laatsch55]

And Richard, you now know there is no going back...

 

[jbeckva]

Missed a few specs there Lad, SNR, residual noise......

Sez typical noise is around .34 uV

 

[laatsch55]

Where's the biggie, although .34 is mighty good.

 

[jbeckva]

Where's the biggie, although .34 is mighty good.

The biggie???

PSRR and CMRR both 120 dB.. dunno why we don't have an actual SNR on the datasheet / maybe Joe can say...

 

[laatsch55]

ThaT'S ODD.





















PERHAPS it's so beyond any oter opponent it's likely to be pared with it's a moot point.