Phase Linear 700 ??

[bigstereo]

Originally Posted by BMWCCA

You can try this link but I may have posted this information previously:

Damn, wish I'd of seen that before I had mine restored and upgraded. It would be cool to have a PL amp that has been touched by the man himself.
Loved that amp. Sold her recently to afford a bigger (128 lb) beast.

[Woofer]

What can I say?
OK, so I'm not that close to God!



That's a Clair Bros. 700 on the bottom missing it's Face Plate.
(... hey, if anyone has a spare 700 Series 2 face, let me know, PLEASE)
There's one behind it too, but at least it's complete and almost mint. (best place for it)
Both 700's operate into 4 ohm loads and always have with no ill effect.
That's a 400 in the middle and then a 200, and then a 5100 Tuner.
The 4000 pre-amp is on the other side of the unit, along with an Amcron EQ2.

Speakers are 4x 2215's in 4530's and a pair of 10 cubic foot ported boxes, and 2421's (yes, I know, should be 2440's but at AU$800pr that ain't gonna happen too soon), plus adaptors on 2309's with 2310 lenses plus 077's all crossed with Crown VFX2A's and a FFX2.
I'm also using 4x 10" speakers from my L40's and L36's for the lo-mids.
For what it is, it's incredibly quiet, and I don't realise it's on most of the time, until the power bill comes around.
As far as popping any of my PL's are concerned, haven't had any problems with daily use for the last 10 years. (... touch wood!)

The Luxman LV103 on the top is on my 4301's. Very nice combo.

It's really just repaired stuff from a pile of rubbish, but it's all I got.

Cheers all.

[mikethebike]

Originally Posted by BMWCCA

I've seen plenty of blowed-up 400s. Never saw any used in "pro" applications. Doesn't deny that people used them for pro use, just that they blew regardless. There's plenty of discussion of why this is and what it takes to fix them and make them safe elsewhere on the Internet, including Bob Carver, himself. Fun diversion but nothing new here.

I had a friend who blew-up a 400 at a yard party driving one pair of ARs. No such problem with my baby Crown D150 even driving my 030s loud enough outside to be heard clear to the Blue Ridge from the Doyles River. To show how hard I was driving it, the Crown had one thermal-shutdown incident because it was the early model version with no faceplate and I played it on it's side on a shelf with the logo pointing out when the feet were intended for the logo to be up. I lifted the amp by shoving a pencil underneath it and it played without further incident for at least eight more hours. That was over thirty-years ago and it's still working fine today.

I have experience with PL 4000, PL 400, Sonic Hologram and the Cube amps. Killed tweeters in L-100 AND L-150. Buy what you want but I prefer CROWN amps to all others.
We called the PL 400 the "FLAME-LINEAR" back in the 70's.

[spkrman57]

A friend of mine still has his

Regards, Ron

[Ian Mackenzie]

Originally Posted by midlife

Can a Phase Linear 700 power amp comfortably operate at a four ohm load? Haven't seen much mentioned about these amps, are they desireable and good performers? Are they compatible with different preamps?

With a fan Yes: per the original owners manual (install 8 amp fuses)

The thing about this amp was its threshold of clipping into 8 ohms was around 450 watts into 8 ohms and 700 into 4 ohms. That was the whole point of the design and high damping factor like 1000 : 1 to drive the ART LST and other relatively low sensitivity loudspeakes. The advent of high voltage transisters used in TV HT power supplies made the 700B a reality.
http://images.google.com.au/images?h...title&resnum=4


Obviously efficiency goes to hell into 4 ohms in a linear amplifier (with such high supply rails) . The problem with 4 ohms is the losses with such high currents and high power levels and the heat. Most of the class leading super amps can now approach 6 fold those numbers into 8 ohms and down to 2 ohms with switchmode PS. The point is a dyanmic range from an amp that can put out such large voltage swings.

http://www.labgruppen.com/downloads/...LM14000_V3.pdf

The Crown amps of that era could not do that and only then in bridge mode.

[Woofer]

It must be remembered that we're talking about amps that are 40+ years old don't forget.
These were the first of the 'Super-Amps' and were at the forefront of technology for the times.
It was a HUGE transition going from reasonably low powered Valve/Tube amps to these Solid State high powered devices.
I think the Crown DC300 came just before the Phase Linear 700, (correct me if I'm wrong), and there wasn't much more about except for maybe the BGW's which came a little later.
(... feel free to add to that list, IF you're old enough!)
Some have said that they don't remember seeing these in 'action' but there were companies about during the 70's and 80's, eg Clair Bros, USA, that must have had a thousand PL's for their huge Concert Touring Rigs.
You may not have seen them, but you certainly heard them.
.... but then again, this only applies to those from THAT era that were out and about at the time.
Some companies used PL's, and some used Crowns.
Same as recording studios.
It was always one or the other, but the one thing most had in common were JBL monitors. A match made in heaven regardless of which amp you used.
We have so much to be grateful for to these two Audio Co's as we wouldn't have some of the most exotic stuff today without their, (PL & C's), pioneering R&D and productivity.
I mentioned before I have a heap of PL's. I'm now starting up a similar Crown set-up. Again from 'found' broken bits.
I don't necessarily prefer one over the other. I love both.
They both have their problems, but there's so many solutions available on the 'net these days, that not having a perfectly working unit is no excuse really.
Anyway, whichever you have, enjoy it/them.

Cheers all.

[Ian Mackenzie]

Agreed,


Has anyone heard of SAE.

I repaired a 50/50 watt SAE power amp about 18 months ago and it was really nice. I replaced most of the transisters including the drivers with original types (darlington outputs) and used more modern low noise true equivalents for the Dual input Diff pairs and matched the HFE. Some capacitors were also past their used by date.

That made a hugh difference from being just another amp to the dizzy heights of a Levinson. Its surprising how different a transister can sound with the same spec. When match with the optimum HFE it can be night and day in terms of resolution and tonal balance. In this amp the previous repairer put in odd types (probably from another repair) so it was a sick puppy for a long time. Now I get a free beer whenever I see the owner!

I think SAE man has a big stash of those.

The point of this post is that if you buy an old Phase Linear it probably wont sound as good as new and even less likely to be working properly if it had been blown up.

[Woofer]

Originally Posted by Ian Mackenzie

Agreed,


Has anyone heard of SAE.

I repaired a 50/50 watt SAE power amp about 18 months ago and it was really nice. I replaced most of the transisters including the drivers with original types (darlington outputs) and used more modern low noise true equivalents for the Dual input Diff pairs and matched the HFE. Some capacitors were also past their used by date.

That made a hugh difference from being just another amp to the dizzy heights of a Levinson. Its surprising how different a transister can sound with the same spec. When match with the optimum HFE it can be night and day in terms of resolution and tonal balance. In this amp the previous repairer put in odd types (probably from another repair) so it was a sick puppy for a long time. Now I get a free beer whenever I see the owner!

I think SAE man has a big stash of those.

The point of this post is that if you buy an old Phase Linear it probably wont sound as good as new and even less likely to be working properly if it had been blown up.

Absolutely spot on Ian....
I think anyone reading this can apply what you said to just about any of the BIG amps of the time.

So the best advice for possible future purchasers of any VINTAGE amp, go over it first before you power it up.
... and as Ian already mentioned, replace a few of the essential bits, eg, make sure all the transistors are matching and working, and chuck out any capacitors in the signal path and replace with the better stuff available today, and be prepared to have the biggest grin on your dial for a good length of time.

SAE stuff was good too I thought. On par with the big ALTEC amps.

I think I'll go and have a nap now....

[Dual-500]

Originally Posted by midlife

Can a Phase Linear 700 power amp comfortably operate at a four ohm load? Haven't seen much mentioned about these amps, are they desireable and good performers? Are they compatible with different preamps?

This question always draws out the naysayers. Gotta laugh. Yes it's true, if you load up a Phase Linear model 700 with a stout 4 ohm load and pour the coals to it - it will indeed go China Syndrome and in relatively short order. I guarantee it.

Now, is it the amp or the user? Not to bash here. It's already been posted the owners manual mentions cooling fans being necessary for high power applications. They are.

Lots of air and air exchange - cool air. I always use 200+ CFM of fans (2 x 100 cfm) on the 700's in commercial use. And ensure the air in the rack circulates properly.

Companies like Audio Analysts, Heil Sound, and Clair Brothers Audio used Phase Linear amps back in the day for many years. That fact speaks volumes about the amps and how robust they are/were.

I used 400's, 700's and 300's in pro sound, disco's and my home system for many years. 3 clubs running 700's through the 80's open 7 nights a week and I had 2 amp failures from the 700's and 1 failure with a 300. Also had 2 portable systems running - one for DJ and one for club bands.

Tore up a few JBL E-120 12" 16 ohm low mids and a few E-155 8 ohm 18's with the 700's until I learned to correctly calobrate the gain structure in the systems with the old Ashly limiters and crossovers.

What I'm saying is they are flamethrower amps and about as reliable as any if properly setup.

For home use, 12v 120mm whisper fans work pretty well - depending upon how hard the amp is pushed at 4 ohms and for how long.

About the only thing one can grip about for these amps is the fan noise needed to push enough air across them to prevent amp failure.