Phase Linear

So, if Bob got 700 watts out of a coffee can, where are the outputs?? What were they mounted to? Wasn't the coffee can?? 16 XPL 909's require a lottle room. That surface also has to be flat, there has to be sockets, there has to be a surface thick enough and stiff enough to lay those TO-3's out in a coherent manner... the McIntosh tests were LOADED, so you couldn't have just the V/A stage testing, it took outputs to buck the current on the loads. At the very least there was a chassis cinsisting of a stiff back or bottom with 2 or 4 rows of outputs with associated hardware, a coffee can is wholly inadequate for that purpose, it could not have happened, think about it, the outputs of the day were no where near what we have now, and bridging a 400 would have put the XPL's in a very precarious situation and I'd bet a weeks pay the breaker at the test site went because of multiple failures of the output transistors.
 
laatsch55 said:
+83DC and - 83 DC, 167 total
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Sounds about right.

Let me ask you about these DC (Direct Coupled) designs. So this 200c I have, is also a direct coupled design and it came with a warning. If there is any DC voltage coming from the preamp, do not use the preamp-get it serviced. Any DC voltages coming from it would be multiplied by a factor of 30... Also NEVER unplug the interconnects while the amp is on because it will fry your speakers.
(the amp has a different input, incase unsure...)

Is this why we don't see much for direct coupled designs, or are there any these days? I think that I would go for fuse protection in the speaker lines to protect them in case of some unprotected catastrophic failure. Do the WO mods address this in any way?
 
The lexicon ( what words meant then don't necessatily mean what they do now) of the day in the DIY and prototype circles was that a Coffee Can was a prototype project with just enough associated hardware to make it work. In the ensuing years Bob was getting so much air time over the CONCEPT of a coffee can amp who was he to correct them. Simple marketing, the interviewer you linked was almost having an orgasm, not an objective question was asked, and the legend still lives AND STILL gets airtime, and as we all know there is no bad publicity, just that which you pay for and that which you don't. The interviewer didn't know enough about electronics to ask anything relevent to refute any part of Bob's story...kinda like the drive-by's and their "reporting" of the Messiah--Barack Hussein Obama...
 
Pure_Brew said:
Sounds about right.

Let me ask you about these DC (Direct Coupled) designs. So this 200c I have, is also a direct coupled design and it came with a warning. If there is any DC voltage coming from the preamp, do not use the preamp-get it serviced. Any DC voltages coming from it would be multiplied by a factor of 30... Also NEVER unplug the interconnects while the amp is on because it will fry your speakers.
(the amp has a different input, incase unsure...)

Is this why we don't see much for direct coupled designs, or are there any these days? I think that I would go for fuse protection in the speaker lines to protect them in case of some unprotected catastrophic failure. Do the WO mods address this in any way?
Click to expand...

Yes they do but nothing except a DC protect circuit will protect the speaks in case of an output failure, in any A/B desigh, not just PL's, Marantz, Pioneer, Sansui, you name it, an output shorts and you have DC on the rails...the rest had DC ptotect circuits designed in, not PL, although if you sent your amp back to the factory they would gladly install one for a nominal service charge. e address this with Don Imlay's DC protect boards,THEY WORK, I have had a 700 and 400 on the K's when I have lost outputs, a genuine real world test with 8K worth of speaks on the line...
 
Direct coupled means the input stage is coupled to the V/A stage without capacitors, and to the outputs from the V/a stage with no caps...and then this is where transfer function comes in...
 
A dc coupled amp can have decoupling caps on the inputs, there was an option on the inputs with the Normal/Direct switch. In normal there was a DC stripping cap inline, in direct, no. Not to be confused with the amplifier stages being ditect coupled...
 
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Thank you for that!

Hey, maybe Bob had a big can lol. Couldn't you mount the devices on the side and use some can material to fin/sink out from it? Who knows. But this guy is a genius of amp design in any case, and if there was a way to do such a thing, I'm beginning to believe that he'd be the one to do it.

Did you ever mess around/see the specs on the Sunfire??? My Lord, when it came out our whole team was offered a special 1-shot deal for $400. And I just couldn't do it at the time. Still kicking myself. It sounded amazing. There seemed to be hardly anything in the chassis lol.
 
Never heard a sunfire Joe. I did have a big Carver, the PT 2400, a dual mone pro type amp, didn't like the sound though and in a head to head test could not drive Timdalf's Soniphase S6's as well as the 700 did. The PT 2400 is advrtised as 750 per into 8, 1200 per into 4 and 3000 into 4 bridged....RMS watts, and it struggled with the S6's, the WOPL had complete control of those massive 15" EVX-155 woofs, and just sounded better too.

There is something very different about the designs, you'd think 750 watts would spank some ass a lot more than 450 watts....watts are watts, RMS anyway...
 
I agree Bob's a genius, but he can't skirt the laws of physics...and if I ever get a chance we're gonna find out...now with my limited knowledge maybe I''m missin a trick and the other white Joe will chime in here I hope...
 
Lee I thought you might like to see this other beast I have. Outputs like a PL400. Had Some fancy copper buss-bar configuration that goes under the output devices, caps & chassis. Kinda pretty on the inside... Heavy as f...
 
Oop I'll try later...
 

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I love the big open face industrial relay. Looks lke a well built amp..
 
laatsch55 said:
I love the big open face industrial relay. Looks lke a well built amp..
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That relay is pretty wild at turn on. Blue flash! Anyway I tried it out. Well...at least it's still functions. Loud sssssssss in the right channel. Then pop. Pop pop...pop. Maybe I should service it. Too bad it's not compare to the PL ready.

Listened to the Jolida most of the day. Back on the 700B now.
 
I knew you weren't ready to kick it out the door yet... got a service manual for the PS??
 
laatsch55 said:
I knew you weren't ready to kick it out the door yet... got a service manual for the PS??
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About the only thing you can find is a schematic that looks like a napkin drawing. Paul Mcgowen CEO/founder was kind enough to reply but didn't have much info. The company has had a bunch of changes since the beginning. There's a hot spot/lifted trace on one of the boards I had fixed. I've been scratching my head on this thing like everything else is this room full of unfinished project/non working gear.
 
Topologically, just from looking it's laid out a lot like a Spec 2. The big 30 amp open relays we use in motor panels to switch 480 on starter coils, big ones. They last forever and have an alloy on the contacts that is remarkable...
 
laatsch55 said:
Topologically, just from looking it's laid out a lot like a Spec 2. The big 30 amp open relays we use in motor panels to switch 480 on starter coils, big ones. They last forever and have an alloy on the contacts that is remarkable...
Click to expand...

Cadmium...
 
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