My First Phase Linear Restore- New Guy to the Forum

[mjstriker]

Hello everybody from San Antonio, Texas!

A little background... My dad has always had a Phase Linear 700 hooked up to some Bose 901's and always loved cranking it up and blasting some classic rock at home. Finally was able to get into vintage stereo when I got my hands on a Phase Linear 400. Always been a tinkerer with electronics and have quite a few years experience with soldering.

Finally have the time and money to start restoring a Phase Linear 400 I picked up a couple years ago. It's been working great just been getting the upgrade bug after reading up on all the forums and websites the past few months.
I upgraded the power capacitors using the kit from white oak which went well. Been using it to power some KLH 5 speakers very well. Decided to hook it up to some Cerwin Vega D9 speakers in the garage to annoy the neighbors. Unfortunately I blew the line fuse and was reading it could be do to a blown outptut transistor. I figured might as well replace them all as from what I have read the unit could use the upgrade. I picked up a bunch of MJ21196G from mouser.com to start the swap.

My question is concerning HFE matching. I measured each one as follows: 54, 50, 5, 62, 59, 47, 15, 43, 83, 47, 3, 29, 50, 78

I know they should be matched to an extent and they appear to all be from the same lot based on the stamp on the back, but how close do they need to be? I was thinking I might be doing something wrong also to get such low readings on some.

I appreciate everyone's help and am excited about being a part of the forum and working on the Phase Linear

 

[Northwinds]

Welcome aboard! I have the same issue when running CV's with the PL400. Mine was upgraded this year and still ocassionally blows a fuse but I have learned what it likes and what is does not. Probably the most dynamic amp I have owned in many years, love it to death. I still am thinking it's the Carver preamp that I use because it just tripped the Nikko Alpha 230 amp's protection circuit I just picked up and I was not even putting the gas to the Nikko

I am resolved to finding another preamp, too much of a coincidence with it happening on two different amps

 

[laatsch55]

Hfe matching with modern TO-3's aren't necessary. I have a Sencore TR-139B and occasionally check.Those are some wild numbers. I'll pull some 96's out of stock and check a few. Gotta go to my grandson's birthday party right now but I'll be back. The emitter resistors force current sharing among the group so they can be a little different. I had a set of D-9's, it liked the 700 much better than the 400.
Are you considering the fully comp option with the White Oak backplane boards?? Quite an improvement.

 

[laatsch55]

You have found a forum which can get you through any PL problem. Joe with White Oak Audio posts asa "Gepetto" here. He is at this time out of the country for 2 weeks. Somewhere in Asia....

 

[jbeckva]

He is at this time out of the country for 2 weeks. Somewhere in Asia....

"Me ruuv rooo rong time"??

(don't mind me.. we're all the "peanut gallery" on this forum, much encouraged..)

Strange enough, I have a pair of D9's. I will say I had to beef up some fuses, but they were the ones in the CV's themselves. Haven't had an issue driving with either the WO'd 700 or 400, but hmmm... you know, some of those earlier CV's are closer to 4 to 5 ohms than 8. I wonder if they had a EC somewhere along the line? I also have the CB and all level controls bypassed on my D9's. Wonder if that's the difference?

 

[mjstriker]

Thanks for such a big response. I know I will have lots of questions in the near future. When it comes to the 400 it has been rock solid even with running the CVs. The only new changes are surprisingly a new pre-amp and the capacitor upgrade. I have talked to joe quite a bit and he was thinking the new capacitors might be bringing out weaknesses in the outputs... Or at least that's what I gathered from our conversation

When it comes to the new transistors I don't know if my cheap POS multimeter is giving accurate results. Unfortunately my nice one doesn't do HFE (go figure). So I do not know how reliable the readings are.

And yes I will be upgrading to full comp when the pocket book allows and I have some free time to set aside

Gonna have to try another preamp I have as seeing that apparently can be a weakness. It's a HK Cotation 17.

 

[lyle]

Thanks for such a big response. I know I will have lots of questions in the near future. When it comes to the 400 it has been rock solid even with running the CVs. The only new changes are surprisingly a new pre-amp and the capacitor upgrade. I have talked to joe quite a bit and he was thinking the new capacitors might be bringing out weaknesses in the outputs... Or at least that's what I gathered from our conversation

When it comes to the new transistors I don't know if my cheap POS multimeter is giving accurate results. Unfortunately my nice one doesn't do HFE (go figure). So I do not know how reliable the readings are.

And yes I will be upgrading to full comp when the pocket book allows and I have some free time to set aside

Gonna have to try another preamp I have as seeing that apparently can be a weakness. It's a HK Cotation 17.

you wont be dissapointed

 

[mjstriker]

"Me ruuv rooo rong time"??

(don't mind me.. we're all the "peanut gallery" on this forum, much encouraged..)

Strange enough, I have a pair of D9's. I will say I had to beef up some fuses, but they were the ones in the CV's themselves. Haven't had an issue driving with either the WO'd 700 or 400, but hmmm... you know, some of those earlier CV's are closer to 4 to 5 ohms than 8. I wonder if they had a EC somewhere along the line? I also have the CB and all level controls bypassed on my D9's. Wonder if that's the difference?

I'd be interested in what you have done with your D9's. I picked mine up from a guy who was running a surround sound receiver through them and was wondering why the receiver kept turning off. . Anyways I picked them up for cheap and was able to get some new tweeters put in as the originals were well fried from the abuse. I'm sure the other speakers took a hit too but I am still working on my knowledge of the speakers to deduce any problems with them.

 

[laatsch55]

Put your meter on the speaker "in" binding posts. Should read about 5.6 ohms on the 9's.

 

[laatsch55]

I've checked 25 ---21196's and they vary from 52-60.

 

[mjstriker]

I've checked 25 ---21196's and they vary from 52-60.

I'm gonna have to mess with the multimeter I have to see how accurate it is. Other than that I might have to pick up another batch to get some closer values. I thought it was weird to get such a drastic variation in values seeing as so many people have told me as long as your lot number is the same you shouldn't have to measure.

 

[laatsch55]

You really shouldn't. With an hfe of 5, that's almost no gain which would put the pre-driver and driver trying to make the current of 3 output devices. Mouser supplied 96's should be better screened than that. Joe has told me numerous times, when in doubt eliminate your test equipment as a source of the anomoly first. So I'd say you're on the right track.

 

[jbeckva]

I'd be interested in what you have done with your D9's. I picked mine up from a guy who was running a surround sound receiver through them and was wondering why the receiver kept turning off. . Anyways I picked them up for cheap and was able to get some new tweeters put in as the originals were well fried from the abuse. I'm sure the other speakers took a hit too but I am still working on my knowledge of the speakers to deduce any problems with them.

Not too much.. I basically took the CB out of the circuit, and wherever the level control was hooked up, took that out too. Now there may have been a WW resistor I vaguely remember, but that too is gone (if it existed). I did try recapping them at one point, but honestly that didn't quite go as well as I thought it would - I actually went back to the "stock" caps over Dayton's. I might try another brand of caps, but the Dayton's just weren't doing it.

 

[Michael F]

You have found a forum which can get you through any PL problem. Joe with White Oak Audio posts asa "Gepetto" here. He is at this time out of the country for 2 weeks. Somewhere in Asia....

I hope he`s not moving White Oak production over there

 

[laatsch55]

No Michael he's not. Still getting boards made in Chicago.

 

[Michael F]

Good to hear. That kind of build quality is rare these days.

 

[laatsch55]

He's coming out with a newlight board that's extremely trick.......



His backplane boards are state of the art. We are extremely lucky that an engineer of his skill level is an audio nut...

 

[NavLinear]

Good to hear. That kind of build quality is rare these days.

From my experience board houses in North America typically make quality printed circuit boards. It's the layout and attention to detail in the design that's critical. Joe does a tremendous job and has a lot of experience in this area. We have lost a lot in the analog design arena but this is where White Oak excels - aka Joe - aka Gepetto. I wouldn't say analog design is a lost art - it's just diminishing.

 

[laatsch55]

I was BS'in with some guys on AK about the build quality of audio in the 70's and how we'll never see that mass produced quality again. I made the comment that the audio nut will have to handbuild anything of quality to be able to afford it. We have custom faceplate makers, couple more things like that and we'll be set!!
And that's where Joe comes in...

 

[NavLinear]

I was BS'in with some guys on AK about the build quality of audio in the 70's and how we'll never see that mass produced quality again. I made the comment that the audio nut will have to handbuild anything of quality to be able to afford it. We have custom faceplate makers, couple more things like that and we'll be set!!
And that's where Joe comes in...

I was fortunate in my early career to have worked with electronic engineers that were masters in analog circuit design. Most were at the end of their careers so I consider myself blessed to have spent some time with them. One engineer that consulted on many projects would take a complex design and simplify it to a few components making the circuit work as well as - if not better than the original design but improved the reliability as fewer components were used. I wish more of it would have sunk in.

I agree with you Lee that with the people assembled here a lot can be accomplished - some cool shit going on.