Phase Linear 700 B On Loan

Elite-ist

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#1
Hi all,

Lucky me, Doug (member fitz43) had loaned me his worked over PL 700 B at the beginning of June. We had met at the Innovative Audio Garage Sale. He graciously offered me his amp on loan and, in exchange, I lent him a few MiniDisc recordings for him to play on his new MD deck he had purchased, which had not quite arrived. I think I got the better part of the deal.

This particular PL 700 B has a storied past which can be followed in this thread:http://forums.phxaudiotape.com/showthread.php/400-Larry-s-Phase-Linear-700B?highlight=Larry's+700B

Yes, this PL 700 B had been built by Lee in early 2011, and, ultimately, ended up with its new owner, Doug. Now I have it, and Geri and I will enjoy listening to it for another week, or so, before returning it to Doug. I did, initially, have it running in my system for a short time, but there was a minor buzz at 0 input from the right channel speaker that had me worried a tad, only because it wasn't my own piece of equipment, and I felt responsible for it while in my keep. So, I disconnected it and had plans with Doug to return it. But, after we discussed the matter, he was OK with me using it and I didn't have an issue as long as he was comfortable with my use of it. Of course, anything beyond 1 on the input control to the PL the buzz couldn't be heard while music was being played.

This is such a nice looking PL with the silver face plate, rack handles, those big meters and sexy back lighting. I even like the script on the front. Give me some time to listen to the sonics more closely, but my immediate comments would be this amp serves all purposes equally well, whether its thumping rock or classical guitar. I haven't had it above the 11 o'clock position on my preamp's control knob with both PL gain controls set at 100%. Some think: why do I need all that power if I don't listen to music at those SPLs? Believe me, at lower to mid levels, this amp proves that reserve power is your friend. What it can do at the top end of the meter range it can easily do without a sweat at the lower levels. You will find yourself, as I did, slowly increasing the volume control on the preamplifier just to hear what it can do, then slowly easing back on the throttle like a big-block Buick.







Here's a little taste of some of Black Sabbath's new album "13". One of my favorite tracks, so far:

Click on image to play video:



Nando.
 
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NavLinear

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#2
As always some really nice photos - thanks Nando.

It's good to hear your feedback as you've listened to many different systems and can provide another good perspective of what a White Oak'ed 700 can do. Besides you do great write ups - maybe you should have been in advertising.

The song you picked was appropriate (and good by the way) and the meters were moving nicely so you this guy cranked up some.
 

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Thank You Nando. We are way past that buzz and more sonically pleasing with the latest Rev "D" board
 

BubbaH

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#5
Can't go past 40 percent without screaming "uncle", eh Nando? I know the feeling.. heheh. 60 percent is about all I can stand on my WO'd 700.
Nice pics, and vid Nando.

While my amps arent quite as big as the PL's the reserve power deal is why I run em. After some serious rental issues, we ended up here. The system got put in a "thats the only place for it" room. So I made due. My older videos which you might have seen, allowed for higher output, without being exceedingly loud. But back to that whole reserve power deal, after several blue, it tends to get there anyways.

How are you liking the new Sabbath so far Nando.
 

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Nando , I did not mean to imply in any way the buzz was any doing of Joe's board, strictly my application of it.....
 

laatsch55

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Yes, this PL 700 B had been built by Lee in early 2011,







Here's a little taste of some of Black Sabbath's new album "13". One of my favorite tracks, so far:

Click on image to play video:



Nando.

And was only the 2ND White Oaked 700 to come out of Gillette...
 

derek92994

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#8
Great unit, looks fantastic and I bet it sounds equally great :thumbleft:
 

pennysdad

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#10
one of my 700 series 2's has a similar problem.
only happens on the right channel when the pot's turned to minimum. (???)
disappears as soon as you turn it up.
I just put it down to the pot, and never given it a second thought.

very nice pictures Nando.....
 

Gepetto

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#11
one of my 700 series 2's has a similar problem.
only happens on the right channel when the pot's turned to minimum. (???)
disappears as soon as you turn it up.
I just put it down to the pot, and never given it a second thought.

very nice pictures Nando.....
Experience is that it is an oxidized TO-3 socket on the back panel...it is more noticeable at low volume. Like power relay contacts, they make poor contact when dealing with logic level signals but work fine with AC level signals across them. Wholesale replacement is the best cure, it is very hard to locate the culprit and even when you do, it will be the neighboring socket a month later.

99% of all PL problems (except the burned out incandescent bulbs) reside on the back wall connections...

This law is almost as important as Rule #1, check your test equipment first!
 

Skratch

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#12
Experience is that it is an oxidized TO-3 socket on the back panel...it is more noticeable at low volume. Like power relay contacts, they make poor contact when dealing with logic level signals but work fine with AC level signals across them. Wholesale replacement is the best cure, it is very hard to locate the culprit and even when you do, it will be the neighboring socket a month later.

99% of all PL problems (except the burned out incandescent bulbs) reside on the back wall connections...

This law is almost as important as Rule #1, check your test equipment first!
I had a similar problem with a TO-3 driver socket. I got myself a tiny little stainless steel brush from McMaster-Carr that will fit through the pin holes of the socket and whenever I change a TO-3 transistor I run it through the hole a few times before I install the transistor.
 

NavLinear

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#14
Experience is that it is an oxidized TO-3 socket on the back panel...it is more noticeable at low volume. Like power relay contacts, they make poor contact when dealing with logic level signals but work fine with AC level signals across them. Wholesale replacement is the best cure, it is very hard to locate the culprit and even when you do, it will be the neighboring socket a month later.

99% of all PL problems (except the burned out incandescent bulbs) reside on the back wall connections...

This law is almost as important as Rule #1, check your test equipment first!
Joe,

Do you have a preferred replacement socket for these? I've looked and found several different types but I don't have first hand experience with this type of socket.
 

laatsch55

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Keystone 3086 I THINK, I'll have to check the part number. You want the one with at least .090 of shoulder depth, it has to go through the chassis, and heatsinks. Chassis is .o30??, heatsinks are .125
 

NavLinear

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#16
I had a similar problem with a TO-3 driver socket. I got myself a tiny little stainless steel brush from McMaster-Carr that will fit through the pin holes of the socket and whenever I change a TO-3 transistor I run it through the hole a few times before I install the transistor.
That's not a bad idea Mark - maybe hit it with some DeoxIT D5 first while cleaning and add a little DeoxIT G5 afterwards for good measure.
 

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Keystone 3086 I THINK, I'll have to check the part number. You want the one with at least .090 of shoulder depth, it has to go through the chassis, and heatsinks. Chassis is .o30??, heatsinks are .125
Keystone 4618, Mouser PN 534-4618. They normally have some stock.

They are cheap sockets, a big weakness in the PL amps (same logo on the socket since the early PL days)
 

laatsch55

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#18
Well, 2 numbers outta 4 ain't bad. THE preferred socket is no socket at all/...................

Buit if ya gotta have em the was some nice green di-something--phthallimate something that are top notch stuff on e-bay not too long ago. Bought all I could get my hands on. The ones that hav the best grip to date are the ones that came with these 10 device heat sinks I bought a couple years ago. Kinda cheapie looking, but exhibited a death grip.....
 

Gepetto

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Well, 2 numbers outta 4 ain't bad. THE preferred socket is no socket at all/...................

Buit if ya gotta have em the was some nice green di-something--phthallimate something that are top notch stuff on e-bay not too long ago. Bought all I could get my hands on. The ones that hav the best grip to date are the ones that came with these 10 device heat sinks I bought a couple years ago. Kinda cheapie looking, but exhibited a death grip.....
I agree Lee, the best is no socket at all :)
 

pennysdad

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Would giving the sockets a squirt with something like de-oxit or even RP7 from time to time, be a worthwhile preventative measure against oxidisation?
 
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