Kevin's "I Want a Phase Linear 700 B White Oaked" thread

[laatsch55]

Oh no Scott, not stopping there, there is a question unanswered, can't have that, not when were this close. That's the only measurement we are lacking for a complete pre-White Oak conversion documentation. It will be done. Works been a bitch the past few days. 10:00 PM last night.

 

[kevin]

See if I got this right. What you are doing is taking a stock 700 testing it in all the was that yall do. Then you will do the same test after the White Oak conversion. Your doing this cause this was a good up and running amp when you started it ????

 

[laatsch55]

Yes Kevin. We have never documented the testying of a stock amp then compared to the White Oak conversion. We had no baseline info. I had asked Joe about a year ago whjat was it about his new board that made the 700's do over 500wpc? His answer " Do we know the stock amps don't"?

Therein lies the reason for doing this. We all know the published specs, but what would a stock amp do in the same conditions we test the converted amps??

In the case of your 700B, not as good as a WOPL. Neutral (not hot or cold) transformer so this should set a good baseline.

 

[kevin]

Ok COOL !!! Thanks !

 

[laatsch55]

Ok, this is what we got at 4 ohms just before clipping. A 15 amp fuse held.

 

[laatsch55]

Frequency response just afterwards into 4 ohms.

Joe, any other tests you can think of before we convert this one??

 

[laatsch55]

In my previous test at 4 ohms I had not loaded the generators correctly. Confidence is high on this last test.

 

[Gepetto]

I would say you are ready to rock Lee.

 

[laatsch55]

That's what Jani was thinkin before she finished up the test report binding.

Another question, there is a definate gain difference in the 2 channels, would most of that difference be in the V/A stage or is there just too many variables to call it from the hip like this??

Attached is the cover of Jani's handiwork.

 

[ksrigg]

Has your new audio analyzer given you the ability to further improve the re-creation of a Phase Linear....fine tuning any of the various components, to do more tests than you could with just DIMM, oscilloscope, and signal generator, or simply the ability to test things with greater accuracy? I know you can now PRINT the results of FR, THD, etc.. but I'm just curious as to how much MORE you can do with the new analyzer...

 

[laatsch55]

So am I Sutton. I've just scratched the surface on the capabilities of this thing. I think the greatsest advantage of this system is being able to test to various standards and then argue the results with greater confidence. i was getting some flack on AK about the tests results I was posting when doing Jer's and your first 700........not any more.

To someone who knows a lot more than me this machine could answer questions I haven't enough knowledge to even ask yet.

 

[Gepetto]

Hi Lee
2 factors come into play on the gain disparities with the original board. Phase used 5% tolerance components vs 1% on the White Oak board. The resistors in the global negative feedback path control the gain, R15 and R13 set the gain.

The other factor is the mysterious R2 factor, the 2.7 ohm (R) vs the 56 ohm (L). My guess is that your amp had higher gain on the right channel than the left.

 

[laatsch55]

Yes Joe, it sure does. It seems to affect other things too. Joe, if you don't mind I'm gonna copy the +20, _20 volt test post to the archives.

 

[Gepetto]

Sure thing Lee, thanks. I just added another post clearing up the schematic intent matching on the White Oak board versus the original PL14 and PL20 schematics.

 

[laatsch55]

Good deal. Lot of good info being posted.

 

[kevin]

Hey You ole HARD WORKER YOU... '' Lee '' Any new news on my MONSTER ??? I know how busy you are but I got on here and had to say something !!!! Have you dug any big holes latley ????

 

[laatsch55]

Yep, was diggin today. Fixin to populate the board for yours tonight. Makin progress.

 

[laatsch55]

Bending leads on a 10 board order is...............tediously monotonous................

 

[Gepetto]

Watch out for carpal tunnel syndrome Lee

 

[laatsch55]

At the least cramps. jeez. Gotta solder some and take a break.