Johnny D's 700 Adventure

[soundude]

laatsch55
Have question for you.. You seem to be knowledgable in the Phase Linear, just installed Joes board in my 700B.
Install went great and amp biased up nicely.
Put onto speakers and played 1khz signal and bias tracked equally. When I played some music through got fuzziness in the right channel. more pronounced in the tweeter. Have MJ15's in outputs and original drivers. Process of illmination confirms its the amp. In your experience have you encountered this?

 

[laatsch55]

Re: Phase Linear 400

Did you put any Dc protect in it? Did you check the Zoebel network?? How about the caps on the transistor wall? And last but should be first--Did you clean the volume pots??

Really, Really nice Avatar BTW.

The drivers are MJ 2741's or RCA 410's??

 

[soundude]

Re: Phase Linear 400

laatsch55
Dc Protect?
I just installed the board and comfirmed it biased first..by dc protect you mean for the speakers? Fused the speakers with 1 amp fast blow and made sure i used test speakers first.
The caps on the transisor panel, there are none...the zobel network at the speaker outs, they seem to be intact and no fried resistors or blacked caps..
Joe is sending me new matched drivers, driver installed look like RCA 66546.
Pots are good and I even jumped connections at pot to be sure wasn't just lazy..
I'm more of a tube guy, build any tube amp but when it comes to transistors to much circuit involved and don't like possibility of dc on my speakers...
Yep nice avatar, angela...whata babe!

 

[laatsch55]

Re: Phase Linear 400

Fusing is a crapshoot for protecting speakers. The PL's were infamous for just one day sending rail voltage to the speaks, fortunately Joe has cured most instances of that-----EXCEPT --- for a shorted output or driver. There are a few DC protect circuit boards available. I would certainly consider one if you have some pricey speaks. My severally modded K-Horns can almost take the full output of a White Oaked 700, which at clipping is close to 525 a channel, insanely sublime sp[l's, as Mark would say.

Back to your question, Joe probab;ly has ypou on the right track. An input differential pair that aren't matched(or even close) will allow more DC in the signal path as well as a lot of noise. Almost all the semiconductors in this particular signal path can do that. What does your DC offset look like??

The 66546's are rebranded RCA 410's. Not the best drivers, and even that is up for debate. I have been p[laying with the MJ21194 as drivers and the MJ 21196's as output combination this weekend and so far they have generated less THD & N than other copmbinations I have tried.
One last thing, what was your source for the 2N1304's and 05's? They can be hair pullers if they are not right also. Desoldering one leg of D9 or D10 will isolate the overcurrent protection designed into the board, and allow you to eliminate that section as the p[roblem.

 

[laatsch55]

Re: Phase Linear 400

Joe should have a large grip of 410's to match from.

 

[soundude]

Re: Phase Linear 400

Joe said he would match them for me so hopefully Ill have them soon. By the caps on the transistor board you mean power supply caps? ! tested at 9500uf and the other off the 10000uf scale.
I had joe put in the 1304/05, was flippin coin many times to do or not so then you see how the flips went...
Just tested the zobel, resistors checked out 7ohms, couldn't check caps, transistors in circuit no reading, will have to unsolder one leg and test..
The channel plays strong just fuzzy sounding so gotta be something in the signal part of the system..I switched from normal and direct on change. Hate chasing noise, if it was a tube amp just change the gain or phase splitter tube....That easy, LOL

 

[soundude]

Re: Phase Linear 400

MJ21194 have the same specs as the outputs...? $4 bucks at mouser...

 

[soundude]

Re: Phase Linear 400

dc offset is 7.8mv left and 8mv on right
Have infinty 4.5s and magnaplanars and the infinity's emits and emims are obsolete so there is no chance they will ever see solid state amps...
Do the boards you mention have turn on delay to, thought the speaker was going to fly out of the cradle when i turned on and the caps charged....had joe do the zener upgrade in the input caps but didnt stop the on/off thump.

 

[laatsch55]

Re: Phase Linear 400

Ok, did you replace the power supply caps?? Caps on the transistor chassis wall. On a "B" there will be a couple .33uf 100volt caps on the left channel output sockets. The only thing you might unsolder at this point is one leg from D9, or D10. that will eliminate the protect circuit from the equation.
How about the shielding on the inp[uts to the board? Have you changed the grounding scheme after installing Joe's board?

 

[laatsch55]

Re: Phase Linear 400

Yes the DC protect boards have on and off muting.

 

[laatsch55]

Re: Phase Linear 400

Did this "B" work previously?

 

[soundude]

Re: Phase Linear 400

laatsch55
No I didn't replace caps in PS, the checked out good. Looked at new caps they are pricey almost 60 bucks. want to make sure the amp is worthy before dumping in upgrades.
As for the caps on the transistor plane, there are none, and there are no signs of anything that was there originally. Its a 700b, think newer than the regular PL700. Maybe they omitted them.
Yeah I'll have to desolder the diodes tomorrow, where on the board are they located near? Hard to see numbers..
inputs are already fully shielded from inputs to pots back to board...wired the board as per joes instructions. No hum anywhere in the signal or output. Just the fuzzies in the right channel.
Biggest fear is the turn on and the way the speakers react...speaker wont like that to much.
Does joe sell the protection boards? Also do they have time delay relay before applying speaker connection? Have a crown PSA2x and has 4 sec delay before transistors connect to speaker output connections.
If you can explain the WLO?1000 upgrade, seen it posted all around the forum...

 

[soundude]

Re: Phase Linear 400

PLWO1000's

 

[laatsch55]

Re: Phase Linear 400

The WOPL is our term for a 700 that's been White Oaked, they test at 500 to 525 a channel---USUALLY--. Yes there is a delay on muting feature in the DC protect boards. The off time is an immediate disconnect from the circuitry to the speaks. Did this amp work before the White Oak board install?

 

[soundude]

Re: Phase Linear 400

Gotta go, 11:00pm and gotta be at work at 5am, looking foward to your response. Great learning...Thx's laatsch55

 

[laatsch55]

Re: Phase Linear 400

No sweat, hope we helped.

 

[laatsch55]

Re: Phase Linear 400

Check these out;

http://www.apexjr.com/capacitorsR.html#Computer

 

[soundude]

Re: Phase Linear 400

I don't remember if it worked from the last time I put away, had 2sd555 transistors in and one blew, replaced with MJ's then put on test speakers and went on shelf so I can build my son his amplifier and speakers and its been on the shelf for few years. was looking around forums and came across the white oak site and PL became a intrest again. So I don't know if it wirked right since it really never seen a quality speaker since I put the MJ's in. I really can be only 3 things, output going bad, driver, or hate to say and not disrespect maybe a transistor on the new board...when I get home going to remove the d9 or d10 diode and try without the 1304/05 in circuit. Let you know tonite, see you then.
Thanks for all the help, hopefully get this working right. Where would I get the protection board from?

 

[laatsch55]

Re: Phase Linear 400

wattsabundant has the boards, you can PM him, he is a member here. That's not disrespecting Joe or his board, shit does indeed happen. When he sells a populated board other than bench testing I don't know if it gets installed in a mule and listened to before it goes. Other than that , hard to get good data unless it's in the unit it will be in. Have a little patience, it will get fixed. The PL's with Joe's improvements make them as good as amps costing ten times as much, their dollar/watt value is extrordinary and they sound pretty damn good also. And , after acquiring a decent test unit the specs are VERY good, had a Ser II 400 stand toe to toe with a Bryston 4B in the testing department, but the Bryston fell short in the "how it sounds " department. That's one thing that still drives me bugf$%#. How can two amps that test close on almost all aspects and then sound so different??

 

[laatsch55]

Re: Phase Linear 400

Do you still have the 2SD555's you replaced??