New output transistors and drivers for Phase Linear 400

[premiumplus]

Hey all,
I've got two Phase Linear 400 Series 1 amps. For now, I want to make one very good one to drive my new Dahlquist DQ-10's. I have my DC protection relay board shipping from Don tomorrow, and I want to get one of my amps kicking some serious butt.
My output transistors are all blue script XP-909's, and I had to pull a couple of them for my other 400. Which got me to thinking, should I replace them all with new replacements? Knowing how critical Ed Blackwood says they are to stability and sound quality, is that a bad idea? If there are good replacements that I can get from Mouser or similar resources, what part numbers are the best ones to use with the PL-14 driver board? And would these be a good choice if I were to buy a White Oak driver board and install it?
Don't you love all these questions?

 

[NavLinear]

Hey Dave,

If you want to upgrade your 400 you may want to look into the new backplane Joe designed along with a new controller board. His designs are solid, the boards are layed out extremelly well - couple that with some new ON Seimconductor audio grade power transistors you'll have a kick ass system. Mouser carries the transistors - MJ21195 (pnp) and MJ21196 (npn). There are several threads that document the installation of these upgrades and you have a choice of either semi-comp or fully-comp outputs. Others will chime in with their thoughts but if you have some coin to invest this would be the E ticket.

 

[premiumplus]

Hey Dave,

If you want to upgrade your 400 you may want to look into the new backplane Joe designed along with a new controller board. His designs are solid, the boards are layed out extremelly well - couple that with some new ON Seimconductor audio grade power transistors you'll have a kick ass system. Mouser carries the transistors - MJ21194 (pnp) and MJ21196 (npn). There are several threads that document the installation of these upgrades and you have a choice of either semi-comp or fully-comp outputs. Others will chime in with their thoughts but if you have some coin to invest this would be the E ticket.

Honestly, I'm not sure how far I want to take the 400's. If I am going to really go for it, I'm leaning towards an upgraded 700B. I think those are the sweetest amps I've ever heard, and I've had a lust for one since the mid seventies!
But in the meantime I want to get at least one of my 400's up and rocking. So if it were you, would you just put in the DC protection circuitry, and cherry pick from the 20 or so XP-909's that i have, use the RCA 410 drivers and start looking for a 700B?

 

[NavLinear]

Hand selecting drivers you have in hand would work - that would save you some money to put towards a 700B. The 410s are what you want for predrivers as you suggested and if the XP-909s are in decent shape why not? You could always trick out a 400 at a later date. Using Don's DC protect board will give you peace of mind.

 

[laatsch55]

21195's are the complement to the 21196's.

 

[NavLinear]

21195's are the complement to the 21196's.

Shit. Even looking at the data sheet I messed up the part number - but I was only off by one. Thanks for catching that Lee.

 

[laatsch55]

Just so's he aint ordered yet. You are welcome sir....

 

[laatsch55]

Dave, don't run past a good lookin 700 Ser I, no difference in sound. In fact after White Oaking I think they Sound better;