PL 700 II Clair Bros Rising from the Ashes

grapplesaw

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Almost done!
The inputs have been wired with Coax to the input phone jacks. Phone jacks have ring and sleeve shorted together. With inputs shorted, there is about 1 & 1/2 mv P to P hum and noise L, 1 mV on R. With the amp connected to a grounded Leader signal generator, There is about 2, (maybe 2 & 1/2) mV P to P, on both chan. I can live with this, only audible with my ear an inch from the speaker, and the amp is wide open, no input pots.
One of the voice coils in my sacrificial speakers tried to escape yesterday when the RCA plug was not fully inserted into the signal generator. I think the amp wants to tell me there is still some 'Flame linear' left in it's blood!
Peter I am sure a little glue and duct tape can put this speaker right.
Just kidding and I am Sorry for your loss
 

WOPL Sniffer

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BTW Perry, I have to do my measurements with HVAC off. I have a Trane heat-pump that produces some noise on the line that obscures measurements when the scope is set to 0.5 mV per division.
Had the amp all back together and upstairs in the main sound system when I found that the Right chan was 10 db quieter than the left----Son-of--gun is what I should have said. As usual, my OCD got the better of me. I found some fancy coax with a braid as well as a foil shield, the best of both worlds according to Henry Ott. Unfortunately I did not realize that it also had a black layer of of something conductive that I mistook for insulation, it came in contact with the centre conductor on one channel and shunted the signal with about 2 k ohm.......If you learn from your mistakes, I should be a genius by now.
Since the amp was open, I thought I would post this pic; I have had issues with the power switches on a couple of amps, would this not be a valid preemptive measure?

I turn my Heater/AC off too when testing. But only on the third Friday of the year and only for 3.2 seconds.... especially during Ramadan.....
 

WOPL Sniffer

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BTW Perry, I have to do my measurements with HVAC off. I have a Trane heat-pump that produces some noise on the line that obscures measurements when the scope is set to 0.5 mV per division.
Had the amp all back together and upstairs in the main sound system when I found that the Right chan was 10 db quieter than the left----Son-of--gun is what I should have said. As usual, my OCD got the better of me. I found some fancy coax with a braid as well as a foil shield, the best of both worlds according to Henry Ott. Unfortunately I did not realize that it also had a black layer of of something conductive that I mistook for insulation, it came in contact with the centre conductor on one channel and shunted the signal with about 2 k ohm.......If you learn from your mistakes, I should be a genius by now.
Since the amp was open, I thought I would post this pic; I have had issues with the power switches on a couple of amps, would this not be a valid preemptive measure?
They have those switches on ebay new... A little pricey but when you gang both sides together and stick a big snubber across, they will last.... There is a heavy duty switch which will fit the series II, you just need to do a little rework. It takes me about a half hour to do it. I'll try to get a pic later. I'm messin with the Jolly Green Giant which is ALIVE by the way. Pics coming soon.... :p
 

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They have those switches on ebay new... A little pricey but when you gang both sides together and stick a big snubber across, they will last.... There is a heavy duty switch which will fit the series II, you just need to do a little rework. It takes me about a half hour to do it. I'll try to get a pic later. I'm messin with the Jolly Green Giant which is ALIVE by the way. Pics coming soon.... :p
The amazing Hulk...
 

Peter S

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Thanks Perry;
Ed sent me a nice cam operated switch but it won't fit in my old original 700 (off set meters). Would this 'rework' make it fit in the 700?

Hi Joe; I was hoping the scope was OK, I still get a flat line when the probe is shorted.
 

WOPL Sniffer

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I though you were doing the S II? As far as the original 700's, I couldnt tell you what would fit. Never had one in hand. Send me a pic and I'll see what I got. I have some of the half-Moon's too.
 

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Moral of this story is, if you put design in a Power Switch, make sure you put design one in that will go the distance...
 
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Peter S

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Thanks Perry, this is a switch that failed in a 700B that was to be sold the next day, so I robbed my old 700. I am not in a hurry for a replacement and yes, my project was the Clair 700 II, FINALLY working beautifully---and dead silent--with the only reference to ground being the input cables. All the equipment in the rack is mounted on plastic shims and pvc 1/4" (ice maker supply line) sleeves on the screws, so the PL will be mounted that way too.
My next project is WOPL'ing a second Clair 700 II, which should hopefully go a little smoother!
 

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WOPL Sniffer

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Never seen a switch like that in a PL.... My Half moons work excellent. I got em in flatted and round shaft. Why the hell did somebody put that lame ass switch in a 700B???? A 700B is worth a $20 switch. Hell, even a 400 is worth that....
 

WOPL Sniffer

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Nice Clair............... I was thinking... since I like to be different, I wanted to mount a headlight switch for a power switch... Just pull the knob and rock out..... Or maybe a turn key ignition switch with a big ass skeleton key//////////////


HUH?
 

oldphaser

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........... this is a switch that failed in a 700B that was to be sold the next day, so I robbed my old 700. I am not in a hurry for a replacement .........
The switch that you have in the photo does not appear to be any switch I've ever seen in a Phase Linear amp. It also looks like the hole diameter in the 700 may have been enlarged to accept a replacement switch which is something I often see.
 

Peter S

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Just day-dreaming before I rip into the second Clair 700 II. The amp just completed is working beautifully. Possibly my imagination or the power of positive thinking but it seems to sound clearer than the quasi-comp 700B that it is replacing, but this is purely subjective.
I am firmly convinced that the fabricated steel shield around the pl 14_20 was a good solution to my noise issue. Shorted input L chan noise went from 3 mV to 1.5 mV. The sides and top of this steel clam-shell were opened slightly from the 90 degree folds pictured. This was to allow ventilation.
My thoughts are to re-route all the AC wiring; have the AC cross from the input side to the transformer side at the latitude of the thermo switches. If the input connections are at the bottom of the pcb, and the input op-amps are at the top, wouldn't ANY location for the AC wiring present an equal noise risk? With the wiring crossing at mid-point, wire runs are the shortest. The Power switch wires could go directly to the transformer side and not "Tee" in, close to the op-amps. Also my (patent-pending) steel clam-shell could then be completely open at the top, as it is at the bottom to alleviate any cooling issues for the control board.
The second amp has a lower 'leakage' issue with the transformer than the amp above, so I will definitely do tests to very that this shield is even necessary on this amp. My main concern is; Any harm in running the AC wires straight across, at mid level?
 

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Peter S

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Hi WOPL Sniffer, it turns out that as long as the only connection to ground ( the rest of my system ) is through the input cables, everything is fine. I heard something about common mode bla bla bla......So this Perry guy was right after all!

Just so hard to take somebody seriously who paints a 700B lime green....
And BTW-----no acid for years.
 

WOPL Sniffer

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Hi WOPL Sniffer, it turns out that as long as the only connection to ground ( the rest of my system ) is through the input cables, everything is fine. I heard something about common mode bla bla bla......So this Perry guy was right after all!

Just so hard to take somebody seriously who paints a 700B lime green....
And BTW-----no acid for years.

That's what I like to hear. :D
 

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Just day-dreaming before I rip into the second Clair 700 II. The amp just completed is working beautifully. Possibly my imagination or the power of positive thinking but it seems to sound clearer than the quasi-comp 700B that it is replacing, but this is purely subjective.
I am firmly convinced that the fabricated steel shield around the pl 14_20 was a good solution to my noise issue. Shorted input L chan noise went from 3 mV to 1.5 mV. The sides and top of this steel clam-shell were opened slightly from the 90 degree folds pictured. This was to allow ventilation.
My thoughts are to re-route all the AC wiring; have the AC cross from the input side to the transformer side at the latitude of the thermo switches. If the input connections are at the bottom of the pcb, and the input op-amps are at the top, wouldn't ANY location for the AC wiring present an equal noise risk? With the wiring crossing at mid-point, wire runs are the shortest. The Power switch wires could go directly to the transformer side and not "Tee" in, close to the op-amps. Also my (patent-pending) steel clam-shell could then be completely open at the top, as it is at the bottom to alleviate any cooling issues for the control board.
The second amp has a lower 'leakage' issue with the transformer than the amp above, so I will definitely do tests to very that this shield is even necessary on this amp. My main concern is; Any harm in running the AC wires straight across, at mid level?
Hi Peter
Yes the full comp version has better soundstage and clarity than the quasi comp. Even though the quasi comp is quite good, you get a somewhat compressed sound from the quasi-comp negative half transistor configuration that is not there in the full comp version. You are not the only observer of that effect. That is why the backplanes were created, to unlock that presence with a fairly straightforward conversion process.
 

oldphaser

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Hi Peter
Yes the full comp version has better soundstage and clarity than the quasi comp. Even though the quasi comp is quite good, you get a somewhat compressed sound from the quasi-comp negative half transistor configuration that is not there in the full comp version. You are not the only observer of that effect. That is why the backplanes were created, to unlock that presence with a fairly straightforward conversion process.
Joe,

Which is easier to accomplish? Rewiring the original output stage or building a WOPL back-plane from scratch?

Also what improvements were made to the backplane boards in Rev C versus the previous Revision B?

Thanks!
Ed
 

Gepetto

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Building the White Oak option is far easier Ed, in addition to providing much higher quality and reliability sockets than the original Keystone sockets. That is why it is offered and that is why nearly everyone chooses this option for conversion.
 

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