Phase Linear and Pink Floyd

[P.L.F.]

a quote from Bob Heil on PL P.A. and about the lack of protection circuit (?)

The big show I remember was the original California Jam in April of 1974. They used Tycobrahe-branded BFA 2000 amplifiers and the power supplies were separate from the electronics, just like you describe for the Pink Floyd PL amps, maybe a copy of your technique. The power supplies used 75VDC rails, so the rated power output might be into 2 Ohm loads or just peak power. They reportedly had 54,000 watts of power for the show, that would mean 27 amplifiers, not counting the monitor amps. They discussed the supply voltage sagging down to 90VAC during the heaviest bass portion of the sound and we know that the original PL amplifiers start to clip when that happens. The White Oak Audio driver board compensates for much of that sagging, but the output suffers when the rail voltage drops. The regulation of that voltage is a nice modification, we'll have to see if we can make it work in our upgraded PL (WOPL) amps.

Re: JUNE is "Ask Bob Heil" Month!
« Reply #303 on: June 29, 2008, 12:48:52 am »

As our client list grew there became situations that didn't require the massive semi truck loads of gear so I designed an 'all-in-one' cabinet using two JBL 2220 15" , our 60 degree radial horn and a pair of those great JBL 2405 tweeters. Driven for the 700 watt Phase Linear amps, this baby was a big stereo system. Load in and load out went VERY quickly and we didn't need our semi trucks to carry it all. Of course it was only used in smaller venues.

This particular one was built for some Jeff Beck tours and it was perfect for him in smaller venues that he enjoyed playing so much. If we could keep Jeff out from under working on his Mustangs, things were great! He loved those Mustangs. Day before the start of the rehearsal (when this picture was taken) he took me on a ride and plugged in one of his 8 track tapes telling me that that was how he wanted the system to sound on this tour! Of course I assured him it would sound good but did NOT tell him it would not have all of that wow and flutter and NONE of that horrible clipping and distortion of the Mustang radio! Smile The tour went great.

Jeff was concerned about monitors. So I made a trip to see Paul Klipsch and asked him to build four of his LaScala 3 way systems but with 12", not 15" speakers. After about 10 mintues of Paul ranting at me about how this will ruin the response and sound, I was able to convince him we needed them so they would have a much lower site line level and we didn't really NEED that extended low end. Those four LaScalas in a semi circle around Jeff was fabulous. The Jeff Beck tours with his great new vocalist Bob Tench was really terrific.

Re: JUNE is "Ask Bob Heil" Month!
« Reply #313 on: June 29, 2008, 10:23:43 pm »
CHANCE wrote on Sun, 29 June 2008 14:57

With regards to the Phase Linear amps.​

Occasionally I have other engineers come here to work. I use, a Phase linear 400 amp for my main monitors. An engineer once told me that they nicknamed them "flame linear" because when they blow, they take out the spkrs too. My fingers are crossed, but has anyone ever heard of this before?​

Hi Chance
Your friends are correct. The Phase Linear amplifiers sounded super and produced a lot of output. They sounded exceptional because they had NO protection circuit. So many of the early high powered amplifiers (especially first generation) had a simple 'crowbar' protection circuit across the output and when the amplifiers were right at clipping, that dang circuit would produced a 'crunchy' or 'clicky' sound to me just as the crowbar was about to reduce the power OR - if way too much output, would turn the amplifier off. I always hated that but what could you do? Bob Carver just removed it and you just had to be very careful not to run the baby any more than about + 4dB into it's calibrated VU meter.

HOWEVER - if you continued to run it higher than that, the output devices would short placing ALL of it's +90 volts DC on your speaker line. Go back and read the story that Bill Mueller told about a Humble Pie show that this happened and we had an additional fireworks show from one of our left side speakers! The crowd thought that was cool....we didn't as we lost an amplifier and a pair of JBL 2204 JBL speakers.

One thing you can do, Chance is to measure the current of your speaker line when you are in the 'hump' mode....as loud as you would ever crank things. Place an in line fuse in that speaker lead and fuse it about 1/2 amp UNDER that limit. This should help you.

We also built a 'manifold' from fiberglass that fit perfectly over the entire heat sink. This manifold had a 5" square opening that expanded out to the edges of the heat sink. The manifold was pop riveted onto the Phase Linear and a 5" box fan was mounted on that opening. This REALLY helped to tame the Phase Linears a lot.

Piece of trivia.....go back early in this session. There is a picture of the original purple Talk Box. That was made from the mold of this manifold. When Joe, Krinkle (Richard Kruzekamp) came up with this consumer Talk Box, I need an enclosure - FAST, so my fiberglass guy took that manifold, closed up the 5" opening. Made a 1.5" hole for the screw on driver and LA LA - we had the Heil Talk Box - at least the first 50. I then had our metal shop build the metal enclosure that has been used over these many decades...

 

[laatsch55]

Thanks PLF...

 

[Skynyrd77]

That was a cool read!!

 

[laatsch55]

The whole thread??

 

[Skynyrd77]

The whole thread??

Yep this was the first time I seen it. Plus the recent addition was cool also..

 

[NavLinear]

The whole thread??

You're not suggesting that Jase has a short attention span are you???

 

[laatsch55]

Well, yeah...

 

[BubbaH]

First time I saw it too. Jason is right though, it is a pretty cool read.

 

[Skynyrd77]

me short attention span?naw !!! weed dont do that.,,,

 

[laatsch55]

I have one anyway then add some weed and it's like multiplying negative numbers, way up on the plus side....

 

[Skynyrd77]

I have one anyway then add some weed and it's like multiplying negative numbers, way up on the plus side....

i know exactaly what ya mean lmao

 

[P.L.F.]

PL Amps in P.A. applications

This is MUST-READ (a part was published here): http://www.prosoundweb.com/article/print/us_festival

And in addition another nostalgic path of Phase Linear amps history, this time on Clair Bros' sound systems, which were also adopted by Pink Floyd on several shows:

Power Amplification
Amplification for the house system comprises Phase Linear 700 amps built to Clair Brothers’ specifications.
The grounding and output stabilizing network was modified to make the output “electronically a little beefier,†and the chassis fabricated from steel rather than aluminum.
According to Jackson - http://en.wikipedia.org/wiki/Bruce_Jackson_(audio_engineer) - “The basic ‘Phase’ has a lame output network. If it goes, it makes the amp tend towards oscillation, which is compounded by the inter-amplifier capacitance of the long feeds we run up to the speakers. The long cable runs also reduce the damping factor by adding unwanted impedance to the amplifier.â€
Clair Brothers used to hang the amplifier racks with the speakers, but if an amp or speaker blew during a show there was no way to re-patch it until after the performance. Instead, it was decided to run heavier (12-gauge) cable, and keep the amplifiers on the ground.
There are 14 amplifier racks with four Phase Linears in each. The top amp in the rack drives the highs in four cabinets (two cabinets per side); the second amp down the mids in four cabinets; and the third and bottom amp the bass (one cabinet per side). The two top amps are loaded to about 350 watts into 8 ohms per side, while the bass amps are rated at about 700 watts into 4 ohms per side. All amps are transformer isolated from the console.

Power Supplies
A standard three-phase, Y-system (200-amp capability per leg) with a ground and neutral powers the show. Clair uses two power distribution panels, one on either side of the stage. Each panel has 12 twist-lock outlets powered by two legs, a ground and neutral. There is also a three-phase outlet to supply the Loadstar motors distribution panels, which requires only the ground - no neutral.
One of the theoretical advantages of using a three-phase, Y-system is that if the loads on each leg are equal, no current will travel down the neutral. Instead, the voltage rotates around the legs and balances out; unfortunately, this does not occur with the type of load Clair Brothers has to contend with.
Power rectifiers in the amplifiers conduct current only at the top portion of every cycle. Such a phenomenon causes peaky, not sinusoidal current waveforms, which tend to cause very high neutral currents. If the main service transformer is not particularly large, or its distance from the amps is too great ,there is substantial power line distortion, resulting in a flattening off of the tops of the incoming power sine waves. This reduces the maximum available power in the amplifiers.
“A lot of the problem is caused because we draw about 150 amps per leg,†Jackson said. “If the system ground is tied to the same point as the neutral at the power disconnect box, and the neutral is referenced through a long conductor, the large, dirty currents flowing through the neutral line will pollute the ground and cause all sorts of noise in the system.â€
In most cases ,Jackson’s crew attaches to the cold water pipe for ground, but be cautious. Sometimes plastic sections will have been substituted for metal pipe, making the ground point invalid. If that’s the case, search for another ground source. If worse comes to worse, Bruce Jackson recommends tying to the box, but warns that the ground must be capable of handling the maximum fault current.

 

[P.L.F.]

Bob Heil purple faced PL 700

I wonder if any pictures are to retrieve of these PL models?

[...] My band purchased a pa from Bob Heil in 1971 which consisted of a Sunn Colleseum eight channel board with a single one octave graphic eq, four bass bins loaded with Cerwin Vega 15's, two of his 60 degree radial horns with JBL 2482's, and a purple faced Phase 700 run at 4 OHMS PER SIDE, mounted in a case with two boxer fans.

This was quite a pa for the time, and years later I found out why we never had a problem with the phase 700.

Bob Carver asked me to represent him and his new hi-fi company, selling the sonic hologram preamp, and the magnetic field amplifier.

He gratiously flew me to Seattle, welcomed me into his home, and blew me away with a three dimensional demo of Dark Side of the Moon.

During that time he told me that Bob Heil was responsible for helping him when he started up Phase Linear. Bob Called him out of nowhere, and told him he would prepay an order for 50 amps! BUT he requiredma purple faceplate, and slow as shit output devices!

Bob Carver"s design philosophy with this amp was to have an unregulated power supply with large reserves, and let it swing hard, and boy did it ever! Those slow devices were rugged, and and Bob Heil was a very smart man.

Mike Chafee [...]

source: http://www.gearslutz.com/board/so-much-gear-so-little-time/144137-phase-linear.html

---

[...] HEY - does ANYONE know of or HAVE one of the purple or blue anodized Phase Linears?

YOu were right, Mike. As I remember, Carver called me and wanted to know if I would like to have a 700 watt amplifier? Are you nuts? You don't have to ask me that...bring it on !...

Bob told me that if I could pay up front he would build 50 of them. I ask that they were built to our 'colors' 400 watt model was blue anodized. 700 watt was Purple. He did. Phase Linear was started and we had LOTS of power....

BUT - I never saved one and have looked for years....

HELP ME PLEASE....anyone know of any - working or not.
Call me...Email...'What Ever Works!' [...]


source: http://repforums.prosoundweb.com/index.php?topic=25656.60

 

[P.L.F.]

Clair Bros. gold faced PL 700

And there were apparently PL700 with golden shiny faceplate too -> see the picture. Maybe because they were used for Elvis Presley PA...?

From the big glowing VU meters on a black face the amps are SAE. From a distance the Phase Linears would look about the same only they had a gold face. The rack to the left is loaded with Phase Linears either turned off or the bulbs are burned out in the meters. Phase 700’s with golden face were called by sound reinforcement guys ‘a shiny front’!

source: http://forums.prosoundweb.com/index.php?topic=138219.10

Enclosed is the picture of probably PL Amp with golden faceplate, not sure though if the same was put into Clair Bros. stacks...

 

[premiumplus]

Very cool information. I used to marvel at the sound reinforcement done at the big shows in the 60s and 70s. The best sound I ever heard was at the Fabulous Forum in Los Angeles (Inglewood, to be precise) on New Years Eve 1976. It was the Bi-Centennial New Years performance of the Beach Boys and I figured it was going to be a boring night...I was into heavier music at the time. Was I ever wrong. Reading this thread it must have been done by the Claire Bros. with the above described hanging amps and speakers. The sound was really fantastic. I spent as much time trying to figure out how they did it as I did watching the show.
Thanks for sharing all this, I love reading and learning about it.

 

[P.L.F.]

Britannia Row powered by PL 700 Amps

On top of Britannia Row P.A. sound systems powered by Phase Linear 700 amps, in the early 70s Roger Waters used Hiwatt amps with a WEM cabinets that he later replaced with a Martin bass bins. He had two of these rigs - one on each side of the drum kit to enable Gilmour to hear his bass. This equipment last until late 70s when guitar tech Phil Taylor built him a new Phase Linear 700 amplified bass rig, later supplemented for The Wall live shows with Martin Philishave mid-range cabinets. And because Roger Waters and his "surrogate" Andy Bown both played bass, there had to be two bass rigs on each stage - two Altec rigs for the front stage and two Phase Linear-amplified Martin rigs at the rear.


Introduced in 1970, the Phase Linear 700 amplifier got its name from its combined output of 350 watts per channel. Redesigned the 700 B was introduced in 1974, the 700 Series Two was introduced in 1978. Performance included 360 watts per channel and other improvements.


source: http://www.watersish.com/archives/cat_amps.html

 

[P.L.F.]

Thanks for sharing all this, I love reading and learning about it.

Pleasure! Pink Floyd is the most meaningful rock band to me... They seemed to choose Phase Linear, at the time - home use originated HiFi gear, for P.A. application mainly because of the sound quality and the headroom, which we all admire until these days... Many famous musicians had PL amps at their home or studio -> http://en.wikipedia.org/wiki/Astoria_(recording_studio) ... This amp has a fantastic story behind!

 

[Skynyrd77]

Very cool stuff!!! Keep it coming.. Thanks

 

[P.L.F.]

Klipsch and PL for P.A. Sound

In early 70's La Scalas were often paired with Phase Linear 700B for P.A. Sound systems:

[...] My professional past with Klipsch started way before there was a Klipsch Pro past. After working part time for Kerry Likis in Birmingham and living in Tuscaloosa, I built my first Klipsch PA with standard La Scalas in 1972. In 1973 I started Ram Sound and the system grew to 12 La Scalas powered by Phase Linear 700s. I eventually split the La Scalas (Klipsch wasn't doing this yet) for more flexibility stacking and coverage. At the time I used standard Heresys with tilt back legs. I added zener diodes to protect the tweeters and drove the pi** out of them with Phase Linears. We were doing all sorts of acts from Iron Butterfly to Dave Brubeck.

When Klipsch finally built pro versions, I sold the old stuff and built a new PA with (8) 4-way MCMs, (8) LSI-splits, and (8) KSMs still powered by Phase Linears. I did concerts and festivals across the U.S. with that PA including the main stage at the New Orleans Jazz & Heritage Festival 1982 through 1986. After working with Klipsch on the 600 project and further monitor development, the MCM system was replaced with an (8) stack KP600 system in 1988. I had given up the Flame Linears when Bob Carver began making pro amps. I still use Carver 1250s and all the '88 model 600s, although drivers were changed and updated with further development. They still sound great and look like new. The other pro speakers I still use are (12) KSM-15II monitors, a couple of KP456s, and some KP682s added for more bottom when I couldn't get anymore 600LFs.

I don't work too much anymore. I stopped trying to grow when Kiipsch moved out of the pro business. I lost some great relationships with Klipsch, Carver, and DDA. Some of my passion died along with them. Midas and KT are still around with the quality they were always famous for. I really did enjoy getting away owning what I wanted to use over what the market pressures dictated. Nowadays I spend free time riding with my Harley friends - I ride a TRIUMPH! [...]

Source: https://community.klipsch.com/index.php?/topic/102887-klipsch-pro-past/

 

[P.L.F.]

A bit of history of live sound and PL700

By Drew Daniels:

In my 57 years of performing music in public, I've seen some amazing things. Half a century of participation and fascinated observation provides some interesting tales to tell.

I'm not relating only a bunch of bad experiences here, though the good ones can be counted on my fingers and toes over a half century. Here are some good ones for the record so we have a baseline from which to judge.

1952 — my first public performance. A recital of students at a Los Angeles accordion student competition. Queen Elizabeth’s coronation in England happened that year. I was 32 inches tall with a “junior†120-bass accordion that went from my chin to below my knees. It was all acoustic. The parents went wild. By 1954 I found the guitar was more manageable for my size, and was singing for the weekend card game crowd at our house—half a dozen aunts and uncles—and I sang all the big band tunes played on “Lucky Lager Dance Time†on KMPC Los Angeles. By six, I was beginning to add some show to the songs, imitating Nat Cole, Tony Martin, Eddie Fisher, Frank Sinatra and some of the other big singers on the new fad, television. Like a lot of kids in Los Angeles back then, there was a succession of school music offerings, choruses, madrigals and choirs, even an elementary school orchestra, then junior high school and high school bands, choirs, madrigals, and drama studies. There were good times and good people came out of the available offerings. In my high school alone during the three years I attended, were Rick Cunha, Mike Curb, Harry Garfield, Dennis Olivieri, Bob Corff, Mary Rings, Tom Sellick, Micky Dolenz, Tom Scott, John and Tom Morell, and Steve Bohanon.

All of the performances of school sponsored music and drama were 100% acoustic—there simply were no microphones or P.A. (Public Address) equipment or instrument amps of any kind at schools, except for the Fender or Silvertone amps we used for the sock hop bands after school in the gym. I started playing guitar "dance combos" in 8th grade. The P.A. for those dances was always a high-impedance microphone plugged into the second channel of a Fender guitar amp. It sounded awful because guitar amps are anything but flat or uniform, had open backs behind the speaker, and were of course, never intended for that use. The combination of such an inappropriate amplifier and a cheap mike usually meant that you turned up the volume until it squealed and then backed it off until it stopped—that was the “setup.†Of course it was usually close to feedback so when you would step aside from the mike, it would sometimes howl, so the “show†at these junior high dances was usually quite unprofessional. A few years of playing with this inappropriate gear being used for P.A., aiming speakers, mikes, and so on provided some insight into the temperamental nature of electroacoustics, but not much science. Books had to be sought and experts consulted, but neither were abundant in 1959.

By the time I was sixteen in 1963 and started working at the local music store after school, musical instrument (M.I.) companies were starting to sell public address equipment into the consumer musician market. There were no manuals describing the technical operation of the equipment, though Shure Bros. microphones did have specification sheets with frequency response and polar plot diagrams on them—all intended of course, for engineer readers, leaving all technical meaning unexplained to consumers. The loudspeakers available at the time were clearly designed for the solo singers in all-acoustic big bands a decade before in the 50’s. It was all basically garbage and all designed by guitar players with no real engineering background who worked at these M.I. companies, The speakers had no high frequency horns in them, the cone drivers were all cheap with horrid, non flat performance (like guitar speakers!). They couldn't keep up with an energetic drummer in a four piece rock band, and were completely inaudible under the screams of fans in stadiums at the first U.S. Beatles concerts. There were a few speakers like these used successfully—commercially at least— in some of the Los Angeles coffeehouses I frequented in the early 60's, where there was one mike and the guitar was typically unamplified. In 1963, amplifier power was almost fixed. Everything was vacuum tube, and sixty watts of high quality power was a big deal. The transistor had been invented in 1947 and first produced commercially in 1951, but would not become an amplifier mainstay until 16 years later in 1967, when the first high power audio amps began to appear. That year I got an after school job at Vega (later to become Cerwin-Vega). The Crown DC-300 and then the Phase Linear 700 ushered in an era of growth in concert sound, and sound levels. Now it was possible for the vocals to be heard over the band even with guitar amps and drums, and it was possible for all of it to be projected to large outdoor audiences.

Jump ahead to 1969. I mixed and recorded the 1969 “Palm Springs Pop Festival†with headliners Ike & Tina Turner, Procol Harum, John Mayall, the Paul Butterfield Blues Band, Lee Michaels, Gram Parsons, the Flying Burrito Brothers, and a dozen lead-off local area bands before the 120° sun went down. There were no monitors and the mix position was on the side of the stage on a folding table. The “console†was a group of several six input (phone plug) Bogen club mixers with spring reverb tanks, all daisy chained together. The two stage mains speaker stacks each consisted of four Vega (pre Cerwin-Vega) folded horn bass bins topped with four stacked and splayed JBL 2350 radial horns and 2440 drivers. It was all bi-amplified with an Altec passive line level, 500 Hz crossover. Phase Linear 700s powered the bass bins, Crown DC300s powered the horns.
AND THERE WERE NO MONITORS.

source: http://www.drewdaniels.com/live.htm