Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thread

Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

ksrigg said:
Laatsch55,
What do you think you could do to a Phase Lineat 400 Series I, or would it be better to just go all in and get a 700B? I used to own a 400 back in the day, and it and my speakers stayed in the shop. I'd love to talk to you about redoing a 400 Ser I or a 700B. Could you PM me? I want all the same thigs Jer wanted...bulletproof..non-speaker eating, non-smoking, and can do wahtever you think is best. Thanks and yes, I want to full treatment....I can buy the parts and send to you, or you can source them. I just wanted to see if you'd do it for me, and about what the cost estimate would be....

Thanks,

Sutton Rigg (this could be a Rigged Phase nor a Phase Rigg or....)
Click to expand...

You're a lucky man Mr. Rigg, this is THE place for Phase Lovers, you could never find a better PL than what comes outta those hands in Wyoming!! He'll get back to you as soon as he returns from fishing :D
 
Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

I did have the list for Black Gates if you wanted to go that route. He put blue LEDs in mine. I also went with an IEC connector. Also new binding posts. I guess mine is going back for the new board. Even without the board it sounds good. I have to say he does a good job.

Larry
 
Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

I'm thinking of going the 400 route instead of the 700, just based on the cost of the hulk unit. $200.00 vs $400.00-$500.00 for working example from the Bay. That assumes they can be made stable. I blew my 400 so many times, and from reading on the web..they really were a faulty design from the get go, so I really don't want to have $1,000.00 or more in an amp that I have fears might blow at any moment. Plus double the wattage only gives you 2 or 3 db more SPL anyway. I'm still trying to see if it is worth doing. Do you have any questions as to the stability of these amps after the complete gutting and modifications? Should I have any fears? They sound like a wonderful amp after the reworking, but I just blew mine so many times....
 
Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

He puts current limiters in. No more smoke. Trust me these amps are not what Bob Carver designed at all. Down on the bottom of the links is White Oak. That is who designed the new boards. Lee did mine before the boards came out. On the bench mine was pushing around 500 wpc. He ran it for a few weeks to make sure everything was fine.

Larry
 
Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

I cruised the White Oak site and left messages for them as well, for the output caps, lights and board. I haven't heard anything back from them, so I guess the best thing for me to do is wait til Laatsch55 returns. Money is kinda tight right now anyway, so it's going to be a cost thing for me as well. I have so many amps and pres I have bought recently, but this is definately my next project. I loved my PL, it just didn't return the love most of the time. When it did work, it was outstanding though. Like my Ludwig drums, I guess I'm just trying to recapture my youth. This amp and my stereo was very popular back in college. I had some major parties back in the SAE frat house, and we all had a ball. The best sounding stereo was competition, and I was up there in the top tier during my years there, as long as the Phase Linear was working...I had to bring my speakers all the way back to Watkins Stereo to have the drivers replaced, and that was bad (they invented and patented the dual coil woofer, and later sold the patent to Polk I believe). I soon learned to fuse the speakers, but the amp had to go back to Mr. Toad's in Johnson City, TN to be repaired. FUN TIMES
 
Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

I finished the install of my White Oak Audio board and no smoke! I had 38mV of DC offset initially. My concern is 46 VAC on the chassis referenced to a good ground. Is this normal? Probably nothing to do with the board but is shows up on the outputs so I cannot make a good power measurement.

Is there a way to isolate or troubleshoot this? My rail voltage is 92.8 VDC with the light bulb still attached.

Thanks,
Mark
 

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Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

ksrigg said:
I cruised the Whit Oak site and left messages for them as well, for the output caps, lights and board. I haven't heard anything back from them, so I guess the best thing for me to do is wait til Laatsch55 returns. Money is kinda tight right now anyway, so it's going to be a cost thing for me as well. I have so many amps and pres I have bought recently, but this is definately my next project. I loved my PL, it just didn't return the love most of the time. When it did work, it was outstanding though. Like my Ludwig drums, I guess I'm just trying to recapture my youth. This amp and my stereo was very popular back in college. I had some major parties back in the SAE frat house, and we all had a ball. The best sounding stereo was competition, and I was up there in the top tier during my years there, as long as the Phase Linear was working...I had to bring my speakers all the way back to Watkins Stereo to have the drivers replaced, and that was bad (they invented and patented the dual coil woofer, and later sold the patent to Polk I believe). I soon learned to fuse the speakers, but the amp had to go back to Mr. Toad's in Johnson City, TN to be repaired. FUN TIMES
Click to expand...

He is doing some design work for us on some amps we bought. He does stay busy. That is for sure. The only thing I don't like on mine is where my IEC plug is. I can't use my big cords. Not enough room for them.

Larry
 
Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

mlucitt said:
I finished the install of my White Oak Audio board and no smoke! I had 38mV of DC offset initially. My concern is 46 VAC on the chassis referenced to a good ground. Is this normal? Probably nothing to do with the board but is shows up on the outputs so I cannot make a good power measurement.

Is there a way to isolate or troubleshoot this? My rail voltage is 92.8 VDC with the light bulb still attached.

Thanks,
Mark
Click to expand...

Hi Mark
I'm just guessing. Lee or Joe will know for sure. Do you have the current limiters installed?

Larry
 
Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

No, but I am only running with the driver transistors in right now. The high voltage fuses are also out.

Mark
 
Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

Stuwee,
I am humbled by your flattering remarks. Now if I was only 1x10 -6 as good a tech as Lee is...
 

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Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

I went back through some posts. Lee was running 98.5 rail voltage I think..

Larry
 
Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

I got brave and removed the test light bulb. Then I cranked the variac up to 120 VAC. My rails went to 100.2 VDC on both plus and minus. My transformer is very slightly warm to the touch after an hour of 400Hz signal through the drivers, so I am going to add the power transistors two at a time and check the outputs as I go.

Mark
 
Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

Now I have a frustrating problem. I have the + rail voltage at the outputs. With the four driver transistors (RCA 410) and both of the - power fuses installed my DC offset is .005 VDC Right and .001 VDC Left. When I put in either of the + power fuses, the outputs go to + rail voltage because R and L are jumpered on the board. I disconnected the power to the board (the connectors make this easy) and the DC offsets at the outputs are fine so there is nothing wrong with the transistor wall.

Help?

Mark
 
Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

Something that I would like feedback from on from my two great beta testers...
I have been spending the last 3-4 days constructing a SPICE computer model of the Phase Linear PL20 design. Having invested that time will allow me to relatively easily make component mods and evaluate the impact. One of the early findings that I am experimenting with fixing right now is a latch up (no not a Laatsch up :-)) condition that is apparently prevalent in all Phase Linear control boards. Partial attempts to fix this are diodes D1 and D2 in the original designs. The SPICE modeling does not support that it fixes this. A better way I have found to totally cure this and is borne out by the modeling is to put a back to back 1N4148 diode pair across C6 (that is diode 1 has anode to C6+ and cathode to C6-, diode 2 has cathode to C6+ and anode to C6-). In reality only one diode is needed to fix the latch up condition, diode 1 but I like symmetry thus diode 2 as well. I was concerned about diode leakage affecting the amp offset voltages but it was identical before and after the mod. Mark you should try this and see if it affects your observation. The latch up condition is that the amp swings to the positive rail on power up so I think you may be seeing this. There are other ways of fixing this latch up condition but they are deleterious to the offset voltage. Would appreciate my beta guys trying this too and report any findings, as I will.

Thx
Joe
 
Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

BTW guys, I attach these on the back side of the PCB. Will send photo later. It is a neat installation and is easy to do.

I am experimenting next on how to further improve the low end of the PL400 and 700B which I think is relatively easily done.
 
Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

My goal on the low end is to get it very close to the Crown DC-300 which is the gold standard as it amplifies down to DC.
 
Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

Results of my listening with the 2 diode addition to C6 on my modified PL400 (White Oak, Cap Kit, Light Board and PL14_20 PCB):
Eliminated turn on thump all together, now nothing at all.
Eliminated turn off thump all together or reduced it to almost nothing which used to occur about 25 seconds after turn off (it wasn't all that bad before but this has improved it further).
Minor kerfluffle (a technical term :-)) immediately at turn off of amp, after I have turned off the preamp prior to turning off the PL400.

Would like to hear your results too.

Joe

So far the results look all positive.
 
Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

Pictures of the recommended modification attached.
 

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Re: Jerry's " ONLY ONE IN THE COUNTRY" Phase Linear 700 Thre

Puppet Master,
I am installing the diodes now... I'll let you know the outcome. BTW, my channel B (right) works fine, the latch up is happening on Channel A. But I understand it could happen on either channel.

Mark
 
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