does anyone here have experience with the 700B from Phase Linear?

[Schu]

does anyone here have experience with the 700B from Phase Linear?

I am looking at the specs and it's quite impressive. I am just curious as to those that have listened to this extremely quite/powerful amplifier.

[oldmako]

Not much love here for Carver stuff. I have a pair of 400s and I'm happy with them em. They make a huge difference with my CF3 and KLF20 which seem to love juice. The 400s are warheads. The 700s are MOABs.

Try - http://thecarversite.com/

[Mallette]

The 700s are MOABs.

I recall them being demoed at trades shows being used to light 500w floodlights. Many thought this was the best use...

Dave

[Panacea Engineering]

Dave,

I certainly would have liked to have seen the circuitry on THAT set up.......

[Schu]

okay... I get the picture.[]

[RRFL]

lol Flame Linear 700.

[Islander]

lol Flame Linear 700.

I've seen them described as one of the few amplifiers that can destroy the speakers they're connected to, when the amp blows up.

[Panacea Engineering]

The Speaker usually acts as a Fuse for the 700B, unless you are very careful. Do you have a need in your system for such an amp? Why are you looking at such equipment for Home Theater use? Just curious..................

[bhendrix]

We tried to use the P.L. 700B for PA work in the early '70s, driving LaScalas. The amp quickly earned the nick-name "Fails Linear", because the entire row of output transistors would fail. I spent a lot of time with a soldering iron and a box of output devices before we surrendered and returned to the Crown DC300. The Crown amps were much more reliable and sounded better.

[RRFL]

lol Flame Linear 700.

I've seen them described as one of the few amplifiers that can destroy the speakers they're connected to, when the amp blows up.

My LaScala lived through the 700 series II. Then I loaned it to a friend and the speaker jack slipped out of the speaker shorted and "another one bites the dust."

[garyrc]

While I get what people are saying (above) I'll point out that they were one of the few amps that sounded good with BOSE 901s ...which needed all that reserve power to come alive. Less powerful amps (Dyna 60 w.p.c. solid state) made the 901s sound bland. The best place I ever heard 901s -- the only place I ever heard them sound good -- Alphonso's Mercantile in Mendocino Village -- used the Phase Linear 700s, then moved on to even more powerful McIntosh amps, which sounded better.

[Mallette]

While I get what people are saying (above) I'll point out that they were one of the few amps that sounded good with BOSE 901s ...

We rest our case! []

Dave

[RRFL]

While I get what people are saying (above) I'll point out that they were one of the few amps that sounded good with BOSE 901s ...which needed all that reserve power to come alive. Less powerful amps (Dyna 60 w.p.c. solid state) made the 901s sound bland. The best place I ever heard 901s -- the only place I ever heard them sound good -- Alphonso's Mercantile in Mendocino Village -- used the Phase Linear 700s, then moved on to even more powerful McIntosh amps, which sounded better.

My understanding from back then, lol, was that some one in Sydney was reworking the 700's and matching the transistors so the resistor that compensated for the mismatches became redundant. Apparently, this improved the performance significantly. I have no idea of how many 700B's I worked with in fully horn loaded JBL Quad 4 Ways that I operated for various people. I never had one blow up on me and everyone was very careful with the rack design loads of cooling extra support the transformer for transport so while it was in the truck in the racks they did not rip of the front panel smash circuit boards and bend the rest of the casing "right off". Great care was also taken in moving the racks and placing them into the truck in certain positions. They were all the rage as they were the most affordable for power output. Generally the 700's drove the W bins and the 45x60's. The mid horns were 400's as were the high horns. A friend of mine named Trevor had a very well configured system with a beautiful Sound Craft mixer and no compression. He had me operate it when ever possible as it never failed while I was using it and I always kept the meters on the scale. I did not have to see how loud I could get it as I was not deprived of volume at home as I had LaScala. Everyone said I always got the best sound out of his system and it was that I mixed backwards setting all the outputs to unity and the channel faders to 0db. Then I mixed from the input trims. His system was very quite and I preferred a little hiss to distortion. Most people liked to see the little red lights flashing everywhere as they tried and struggled to get more level. "Wrong". So the 700's would live if you did not abuse them and I actually got very good results with them. It's always a case of maintaining sufficient headroom, the more the better.

[boom3]

IIRC, the Phase Linears used output transistors that had a V+ of 120 v, same as US mains voltage. This meant all was needed was a rectifier and filter caps, no huge step-down transformer required. This also meant that a failed output transistor could put 120v across the speaker load. [|-)]

[RRFL]

The Australian ones looked like this from the back. Also when the main capacitors blew their tops of they blasted across the top of the main circuit board.

[Mallette]

The Australian ones looked like this from the back. Also when the main capacitors blew their tops of they blasted across the top of the main circuit board.

Crikey mate! Can you imagine trying to get on an airplane with that? "Meltdown" isn't just for nukes anyomore...\

Dave

[garyrc]

I preferred a little hiss to distortion.

I agree. I'll take hiss anytime.

There was one place in the '70s that had both Phase Linear 700s, and Crown (300s?). They had a whole approx 40 foot wall of speakers, with a Klipschorn in each corner (clearly the best sounding).. In A-B tests the two amps seemed so close to sounding the same that the owner and I managed to confuse ourselves as to which was playing (at a loud, but not Filmore, level.) So, maybe they sounded good until you blew them up. In those days, every once in a while people would blow an amp in a Rock venue (speakers, too, naturally). That was what happened when the sound was so loud that the dirt bounced up and down on the sidewalk.

[djk]

"IIRC, the Phase Linears used output transistors that had a V+ of 120 v, same as US mains voltage."

You remember wrong.

The PL700 runs on ±110V DC, 120V AC would be 340V P-P.

"This meant all was needed was a rectifier and filter caps, no huge step-down transformer required."

Fiction.

"This also meant that a failed output transistor could put 120v across the speaker load."

In theory, 110V. But only for a brief time until the fuses blew. The biggest problem was people trying to drive 4Ω speakers (like Klipsch), and using the wrong fuses. Many morons forced AGC fast-blow fuses into the AGX holders, AGX are special fast acting instrumentation type fuses, AGC are stone slow by comparison. Also, AGC types back then could only interrupt 120V up to about 5A, so the fuse would internally arc (turn black) and carry unlimited current for a long time.

Inept repair compounded the problems, the germanium transistors in the limiter failed open, the tech doesn't spot it, it goes out and blows up again.

Only use MJ21196, and match them. The gain-bandwidth product is constant, so select for the lowest gain you can (they're faster that way).

SOA at 100V

MJ21196=200W

MJ15011=125W

MJ15024=100W

[boom3]

Hmm, mebbe I am mistaken...I thought they didn''t use a power transfomer at all..

[djk]

"Hmm, mebbe I am mistaken.."

I was tempted to call you 'barking mad', but am too polite to do so.