phase linear
- Thread starter Locobreth
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frommerstop
Super Member
Actually, Phase Linear (often nicknamed Flame Linear) had much more of a reputation for self destruction than harming other components. 
Phase Linear made a number of very good components, but too often QC issues caused problems when they were new... so much so, that my local dealer wouldn't deliver an unopened amp to you - the manager insisted that ALL Phase Linear components were tested before they would release them to their costumers! I seems the ones that survived a few weeks were likely to work indefinitely, so I don't think they were bad designs, just spotty construction. Yours has apparently survived all these years, so I guess you have a good one! :thmbsp:
Simply having a powerful amp shouldn't cause any issues with driving even very sensitive speakers, assuming you don't have toddlers &/or drunks fiddling around with your volume controls! More power just allows you to also drive less sensitive speakers, but there's no real disadvantage in having more than enough to drive a more sensitive model and if you're nervous, you can always use smaller fuse in the output. Though an argument can be made for synergy, or one amp sounding "better" than another on a particular speaker, you could just as easily use that amp to run a Klipschorn, or an AR9.
Since you do now have such a powerful amp, you can consider almost any speaker that sounds good to your ears with little concern over being able to feed it well. IMO, that's the strongest argument for "monster" amps. In short, if you had a flea amp, I could tell you what you couldn't pair with it, but in the case of a big, stable amp like yours, the sky's the limit!
Phase Linear made a number of very good components, but too often QC issues caused problems when they were new... so much so, that my local dealer wouldn't deliver an unopened amp to you - the manager insisted that ALL Phase Linear components were tested before they would release them to their costumers! I seems the ones that survived a few weeks were likely to work indefinitely, so I don't think they were bad designs, just spotty construction. Yours has apparently survived all these years, so I guess you have a good one! :thmbsp:
Simply having a powerful amp shouldn't cause any issues with driving even very sensitive speakers, assuming you don't have toddlers &/or drunks fiddling around with your volume controls! More power just allows you to also drive less sensitive speakers, but there's no real disadvantage in having more than enough to drive a more sensitive model and if you're nervous, you can always use smaller fuse in the output. Though an argument can be made for synergy, or one amp sounding "better" than another on a particular speaker, you could just as easily use that amp to run a Klipschorn, or an AR9.
Since you do now have such a powerful amp, you can consider almost any speaker that sounds good to your ears with little concern over being able to feed it well. IMO, that's the strongest argument for "monster" amps. In short, if you had a flea amp, I could tell you what you couldn't pair with it, but in the case of a big, stable amp like yours, the sky's the limit!
Actually, Phase Linear (often nicknamed Flame Linear) had much more of a reputation for self destruction than harming other components.
How amusing. I have a 700 series 2 at home that my friend got the speaker wires crossed on, and now its got a partially dead channel. Thats my project for this week.
Bill Stevens
Active Member
Phase Linear misunderstood
Bob Carver wrote a very interesting article about his amplifiers that appeared in Audio magazine back in the 1970s. The significant difference at the time, if my memory is right, was that he used an unregulated power supply, whereas most others used a tightly regulated power supply. He explained that the unregulated supply resulted in large voltage swings and that as a result his amps could handle music peaks without clipping that were equivalent to much more powerful amps than even these already extraordinary amps. He argued well ahead of his time that large amps which did not clip sound better. I think the perception that Phase Linear amps damaged speakers came from people who drove them too hard, an amp that clips at the power levels that his amps could deliver is capable of damaging most any speaker. I also think that if the load on the amp was too low (as in low impedance - think double large Advents for example) and the amp was driven very hard that heat was potentially a detriment to their longevity, but that is only my opinion. In the interests of full disclosure I still own a Phase Linear 400, bought in the 1970s. Bob Carver used to bring his prototypes to the store where I worked while in college to have them tested during McIntosh clinics. This was before he started Phase Linear in the basement of the local A&P. Good guy, always thinking, always cordial and courteous to everyone he met.
Bob Carver wrote a very interesting article about his amplifiers that appeared in Audio magazine back in the 1970s. The significant difference at the time, if my memory is right, was that he used an unregulated power supply, whereas most others used a tightly regulated power supply. He explained that the unregulated supply resulted in large voltage swings and that as a result his amps could handle music peaks without clipping that were equivalent to much more powerful amps than even these already extraordinary amps. He argued well ahead of his time that large amps which did not clip sound better. I think the perception that Phase Linear amps damaged speakers came from people who drove them too hard, an amp that clips at the power levels that his amps could deliver is capable of damaging most any speaker. I also think that if the load on the amp was too low (as in low impedance - think double large Advents for example) and the amp was driven very hard that heat was potentially a detriment to their longevity, but that is only my opinion. In the interests of full disclosure I still own a Phase Linear 400, bought in the 1970s. Bob Carver used to bring his prototypes to the store where I worked while in college to have them tested during McIntosh clinics. This was before he started Phase Linear in the basement of the local A&P. Good guy, always thinking, always cordial and courteous to everyone he met.
barkerd
Super Member
agreed "flame linear" is a much overused and inaccurate term usually bantered about by people who have never owned one. Carver's amps are about headroom and dynamic range. The issues with them stemmed largely by people using them in pro / pa environments where they were pushed to their limits continuously . Home use will rarely result in issues. In terms of longevity there is a mountain of common knowledge pertaining to their resurrection / modification/ and longevity mods. There are also speaker protection circuits available as an add on. I own two PL400's that punch way above their weight in terms of dynamics / clarity/ and brute power. Enjoy. Definitely worthy of the effort to rebuild and maintain.
JoeESP9
ESL's & tubes since 83
Very few amplifiers then or now use fully regulated power supplies. Regulation is quite common on the input driver stages but relatively rare on the output stages.
Fully regulated power supplies for an output stage tend to be quite expensive as they are current devices.
Well, I actually got to working on the 700-ii tonight. It had the wrong rail fuses installed, but they were 4 amp instead of the specified 5 amp. One blew. Checking the outputs per the service manual turned up one shorted transistor. With it out of the circuit, initial testing tells me it has a reasonable chance of making sound again with a new transistor.
P.L.F.
Active Member
Hi,
You should replace the whole bank of power outputs, in which the shorted transistor was found. Not only the one that has gone. Check again the 700 II Service Manual for troubleshooting details and you may have a look here too: http://www.audiokarma.org/forums/showthread.php?t=293316&page=17 -> specifically see post #245 and it's attachments. And keep the same type of outputs per channel (upper & lower pole). There is a specific factory bulletin on this point, usually attached to SM. If obsolete, then the whole output stage calls for replacement...
Then you may also consider going full White Oak Audio conversion - Laatsch55, one of best PL experts on AK, may guide you doing so :yes:
Good luck!
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P.L.F.
Active Member
Yes, on top Meridian transport & DAC combo, then Carver C-4000 preamp, PL 5000II tuner, PL 1100II eq., PL 1200II RTA, PL 4000II second pre for multiroom purposes and PL 700II fully comp power amp... (pictures of all the units are here -> http://www.phaselinearhistory.stereomanuals.com/components.htm).
Cheers
Might want to check with Northwind - He's been playing with Phase Linear amps with Cap upgrades, new mainboards,
LED lamps on the meters, and protection circuit from White Oak Audio.
He's got a friend that's involved in doing rebuilds and upgrades and it sounds like a MAJOR improvement in quality
as well as adding some much needed protection to the output - so you don't fry a pair of speakers ...
He had a WOPL (White Oak Phase Linear) 400a for sale on AK this morning and it sold VERY quickly ...
I read the build thread on it earlier but don't have the link here at home
so I did a google and found it ...
http://forums.phxaudiotape.com/forumdisplay.php/68-WOPL-Building
LED lamps on the meters, and protection circuit from White Oak Audio.
He's got a friend that's involved in doing rebuilds and upgrades and it sounds like a MAJOR improvement in quality
as well as adding some much needed protection to the output - so you don't fry a pair of speakers ...
He had a WOPL (White Oak Phase Linear) 400a for sale on AK this morning and it sold VERY quickly ...
I read the build thread on it earlier but don't have the link here at home
so I did a google and found it ...
http://forums.phxaudiotape.com/forumdisplay.php/68-WOPL-Building
Bill Stevens
Active Member
barkerd;... Definitely worthy of the effort to rebuild and maintain.[/QUOTE said:
P.L.F.
Active Member
I'd suggest to send a PM to Laatsch55 (http://www.audiokarma.org/forums/showthread.php?t=600954). The White Oak Audio solution for PL700 (B) Series I and II is well covered here: http://forums.phxaudiotape.com/forumdisplay.php/68-WOPL-Building.
Good reading!
P.L.F.
Active Member
Yes, but watch out the impedance... Min 8 ohms... -> link:http://www.audiokarma.org/forums/showthread.php?t=310160&referrerid=56853
There was also PL factory service bulletin on this topic with another approach but cannot find it at this moment. Generally they were suggesting a transformer connected to the inputs, as to bridge an amplifier you simply invert the phase of one channel. You may do this with a passive transformer. An unbalanced to balanced line level transformer was exactly the solution from Lynnwood PL factory tech support...
The transformer connection scheme is here:
http://www.audiokarma.org/forums/attachment.php?attachmentid=179424&d=1258205577
Putting a cooling fan is a must if you want bridging PL amps.
But besides theoretical possibility to go for the bridged mode - what for you'd need such power? PL amps are sensible to proper current sharing and additional stressing the output stage with mono conf may cause its unexpected failure. DC protection is then your only hope to save the speakers... If you had it....
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elza
Active Member
Part of it perhaps but the main problem was no DC protection for the speakers. If the output shorted you’d have 80 volts going to the speakers. This turns your woofers into 800 watt space heaters. (This is simple ohm’s law not accounting for any droop in the PS output. Whatever the droop there are plenty of reports of speakers catching fire.) This is easily and cheaply corrected with an add-on DC protection circuit.
I’ll roundly second the White Oak mods. I replaced the control board and PS caps in my PL400 and the difference is nothing short of amazing! (You can read about my exploits here if you are interested. http://www.audiokarma.org/forums/showthread.php?t=489394 )
qdrone
Music is my mistress
The Carver Amazing Loudspeaker
Read an article where Bob carver stated the optimum power for these speakers 1250 watts a side. I bought a pair back in the day and loved them,this would give enough crank for them. I have always seen them being sold but the tweeters are always fried. I would like to find a pair in decent shape again. Yeah high end stores were selling them back then and telling them 250 watts was plenty,gee no wonder the tweeters were fried all the time,I had a friend who ran bridged adcom 555's and he was still frying his tweeters because he liked to listen to classical at deafening levels.
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