Don Imlay's Phase Linear 400 Series II Quasi -Comp.

[laatsch55]

I'm just a few minutes away from hearing it myself.

 

[laatsch55]

DAYAM!!!! Like a black hole for noise. With pre-amp at null, no noise, with pre-amp at 0db( which i have done only twice before) barely audible. This IS the quietest amp I have heard here.

 

[laatsch55]

Great definition, like any Joe board equipped amp.

 

[laatsch55]

I can now prove WHY it' so quiet!!!!

 

[laatsch55]

BTW-- The Spec 1 output at 0db is 7 volts at 600 ohms.

 

[laatsch55]

Crosstalk
A to B , output 18volts, input 500mv, 1KHZ------ Minus 80.92 db
B to A, output 18.020 volts, input 500mv-----Minus 90.86db

Signal to noise ratio-unweighted 10 to 80khz
A ---@100.1 mv input and 1.014 khz------82.9 db
B----@ 100.1 mv input and 1.014 khz-----82.5db

Signal to noise ratio-unweighted 10- 80khz
A----@ 500 mv input and 1.001 khz-----95.3db
B-----@ 500 mv input and 1.001 khz-----95.6 db

 

[Gepetto]

Excellent results Lee, nice tool you have there in that AP

 

[laatsch55]

Ah Joe, you'd be like a kid in a candy store!!

 

[laatsch55]

When the music stops, I forget it's on, THAT'S how quiet it is.

 

[Gepetto]

Its one of the few upsides to getting older and losing our hearing, our amps just sound quieter Nice work Lee.

 

[laatsch55]

That's why as you get older your instruments must get better. Thanks Joe, appreciate that.

 

[laatsch55]

I humbly admit I have forgotten a most important test----------------frequency response-----a test the AP is ideally suited. I shall remedy this omission forthwith.

 

[mlucitt]

Lee's Testing Service. Send your amps and pre-amps, Lee will test the heck out of them. No amp too big or too small, come one come all, to Lee's Testing Service.

 

[laatsch55]

Yep, kill em all and let the amp god sort em out!!

 

[laatsch55]

Joe----when running a freq response sweep, and you can zero your reference level, what level is recognized as standard, or is there one??

 

[Gepetto]

It varies but a lot of time you see 1W output cited as the power level that the frequency response is measured at. For this amp a more meaningful level would be 10W into 8 ohms IMO.

 

[laatsch55]

Might have went over that. I did one with 0dbr at 250mv input correlating to 9.021 volt output all into 8 ohms. I did a second one at 500mv input and 18.023 output. Almost idedntical results.

I will run one at 10 watts.

 

[laatsch55]

250 mv input is 10 watts output.

 

[laatsch55]

At one watt, 10 watts , or 40 watts very little difference in response.

 

[laatsch55]

First two pics, 250 mv input, 10 watts output. Second two pics 78.25 mv input, one watt output.