Rare Phase Linear stuff

[oldphaser]

Here is a photo I took of Bob Carver this afternoon with my Phase Linear 700 (made in 1970) (a.k.a. Kelly DeYong 700 since Kelly DeYong ended up with some of them in Vancouver, BC). This was the second generation of the Phase Linear 700 amplifier. It came out after the "bridge amp" and before the PL0171 series pc board in 1971. Exact production numbers of this amp are unknown. This is the only known survivor at the moment. What is also unique about this amplifier are trimpots in the protection circuit. I also have a schematic.

I asked Bob how to adjust the trim-pots in the protection circuit. Apparently they were adjusted for "common-mode conduction" at 20KHz and at rated output.
There are some very interesting articles on the internet and in some of the Phoenix forums about "common-mode conduction",..... quasi-complimentary output amplifiers,...... using slower output transistors, etc.

I saw firsthand an example of common-mode conduction many years ago on a 400 series 1 amplifier. The older slower devices would blow fuses when the amplifier was being driven at 8KHz or higher into a 4 ohm load. This did not happen when I was using MJ15024's as output devices. However one must be made aware of how to deal with any oscillations when using faster devices (i.e. MJ15024's, MJ21194's, MJ21196's) in circuits that were originally made for slower output devices (i.e. PL909, XPL909, FPL909). One must possess the proper test equipment and knowledge on how to deal with these oscillations when and if they occur.


As a side note: I have also attached a copy of US patent number 3,727,148 "Amplifier With Protective Energy Limiter Circuit Components". It does not go into "common-mode conduction". However it does discuss the protection circuit Bob designed.

 

[oldphaser]

Steve Johnston with Bridge Amp

Here is a photo I took of Steve Johnston yesterday afternoon with my Phase Linear 700 bridge amp (made in 1970). This was the very first generation of the Phase Linear 700 amplifier. Approximately (3) were built. This is the only known survivor. No known schematic exists.

NOTE: Steve Johnston was Bob Carver's partner at Phase Linear.

 

[oldphaser]

Steve Johnston with Kelly DeYong Phase Linear 700

Here is a photo I took of Steve Johnston yesterday afternoon with my Phase Linear 700 (made in 1970) (a.k.a. Kelly DeYong 700 since Kelly DeYong ended up with some of them in Vancouver, BC). This was the second generation of the Phase Linear 700 amplifier. It came out after the "bridge amp" and before the PL0171 series pc board in 1971. Exact production numbers of this amp are unknown. This is the only known survivor at the moment. What is also unique about this amplifier are trimpots in the protection circuit. I also have a schematic.

NOTE: Steve Johnston was Bob Carver's partner at Phase Linear.

 

[Northwinds]

Cool!!!!! Thanks for sharing your photos and info!

 

[Gepetto]

I asked Bob how to adjust the trim-pots in the protection circuit. Apparently they were adjusted for "common-mode conduction" at 20KHz and at rated output.
There are some very interesting articles on the internet and in some of the Phoenix forums about "common-mode conduction",..... quasi-complimentary output amplifiers,...... using slower output transistors, etc.

I saw firsthand an example of common-mode conduction many years ago on a 400 series 1 amplifier. The older slower devices would blow fuses when the amplifier was being driven at 8KHz or higher into a 4 ohm load. This did not happen when I was using MJ15024's as output devices. However one must be made aware of how to deal with any oscillations when using faster devices (i.e. MJ15024's, MJ21194's, MJ21196's) in circuits that were originally made for slower output devices (i.e. PL909, XPL909, FPL909). One must possess the proper test equipment and knowledge on how to deal with these oscillations when and if they occur.


As a side note: I have also attached a copy of US patent number 3,727,148 "Amplifier With Protective Energy Limiter Circuit Components". It does not go into "common-mode conduction". However it does discuss the protection circuit Bob designed.

Otherwise known as cross conduction Ed. Speed is your friend. You can never have output devices that are too fast.

Nirvana is semiconductor devices in your amp that do not come into play and impart any significant phase lag before 890KHz

 

[laatsch55]

So it's the circuit not the devices that usher in phase lag/lead??

 

[oldphaser]

COFFEE CAN AMP/ HISTORY OF SEATTLE AREA MCINTOSH CLINICS 1968-1971

I spoke to him about it a number of years ago. There are a variety of different stories I have heard from people that were at the McIntosh clinics or knew Bob at the time. Some people say it exists some people say it doesn't. Some people say it refers to an open chassis. Others say it was a coffee can full of blown output transistors that were accumulated while Bob was designing the original 700. Some say it was kicking around for a while as a door stop. I have seen photos of a coffee can amp in a brand new Folgers coffee can. Needless to say, I will check into the "coffee can" story more for you.

I have put together a little history on the McIntosh Amplifier Clinics that were held in the Seattle area from 1968 thru 1971. It was during this period Bob Carver would bring his amplifiers to the McIntosh clinics. The first amplifier was a 300 watt tube amp in (2) or (3) chassis that was built for Dave Ladely in approximately November 1967. I am not sure if there was only 1 amp (MONO) or (2) amps (STEREO). It was at one of these later clinics that the legendary "coffee can" amp is said to have appeared.

I have included a copy of the test report that was done at the clinic on January 15, 1971. (See attached file). It was at this point I would have to assume that the PL0171 pc board first appeared.


McIntosh Clinics (Washington)
NO CLINICS IN 1967
-------------------------------------------------------------------------------------------------------------------------------------------------------
August 12 & 13, 1968 Stereoland 650 S.W. 152[SUP]nd[/SUP] Burien
November 14, 15 & 16 1968 Electricraft 1408 Sixth Avenue Seattle
March 3 & 4 1969 Magnolia Camera & HiFi 2231 32[SUP]nd[/SUP] West Seattle
August 15 & 16, 1969 GRAM A FON, Ltd 17171 Bothell Wy. N.E. Forest Park Shopping Center
March 5 & 6, 1970 Magnolia Hi-Fi 2231 32[SUP]nd[/SUP] W Seattle
August 10 & 11, 1970 GRAM A FON, Ltd N. E. Ballinger & Bothell Wy N.E. Forest Park Shopping Center
January 15 & 16, 1971 Seattle Stereo Center 2440 1[SUP]st[/SUP] Ave South Seattle


PHASE LINEAR 700 INTRODUCED IN EARLY 1971

More than likely Bob stopped at this point bringing his amplifier to the clinics.
I have included the rest of 1971 anyway below:

July 15 & 16, 1971 GRAM A FON, Ltd 17171 Bothell Wy. N.E. Forest Park Shopping Center
August 15 & 16, 1971 GRAM A FON, Ltd 17171 Bothell Wy. N.E. Forest Park Shopping Center
November 18, 19 & 20, 1971 Electricraft 5030 Roosevelt Way N. E. Seattle
“ “ 10623 N. E. Eighth Bellevue

Ed

 

[oldphaser]

SEATTLE AREA MCINTOSH CLINICS 1968-1971

I have been asked by a close friend to provide him with some enlargements of the ads that appeared in the Seattle Times.
Here they are saved as .png's.
NOTE: I also have them saved as bmp's (rather large file sizes) and jpg's, should the png's not work out.

Ed

 

[oldphaser]

SEATTLE AREA MCINTOSH CLINICS 1968-1971

I have been asked by a close friend to provide him with some enlargements of the ads that appeared in the Seattle Times.
Here they are saved as .jpg's.
NOTE: I also have them saved as bmp's (rather large file sizes), should the jpg's not work out.

Ed

 

[laatsch55]

Very interesting stuff there Ed!!

 

[laatsch55]

"Is your amplifier sleeping on the job?" Love that one!!!

 

[laatsch55]

jpg's worked fine Ed.

 

[oldphaser]

SEATTLE AREA MCINTOSH CLINICS 1968-1971 (BOB CARVER'S RESPONSE)

I just got a response from Bob Carver about the McIntosh amplifier clinics. I forwarded him everything I posted on Phoenix about the McIntosh clinics.

Here is what he had to say:

Oh Wow! This is great stuff! Man, what a trip. I can't remember exactly where that graph was made; I can see the inside of the store, Dave O'brian and his test bench, and him signing the graph, but I'm not sure of the store and its outside. It was either Seattle Radio Supply or Seattle Stereo Center. I think. It'll come to me if I concentrate this next week.
I never worked for Seattle Stereo Center, but I helped out from time to time. I was a roving "tough-dog-man" for many TV shops at the time, even while working for Harry at Sea-rad and at Almvig's in the U district.

I have lots of stories; we need to start a tape recorder, tell stories and adventures, then get them transcribed.

Wow again!

More adventures later.
Bob Carver


Ed

 

[laatsch55]

Now THAT'S cool ED!!

 

[oldphaser]

Photos of Seattle Stereo Dealers Where McIntosh Amplifier Clinics Were Held

Here are a couple jpgs of some of the Seattle stereo dealers where the McIntosh amplifier clinics where held.

Electricraft

Magnolia Camera & Hi-Fi

Seattle Stereo Center

Included in the jpg's is a picture of Seattle Radio Supply where Bob Carver once worked. He also met Rodger Rosenbaum and Ray Weikel there. Rodger and Ray were (2) fellows who worked for Bob's TV repair business and helped with the development of the first Phase Linear 700.

http://www.taihs.org/wp-content/uploads/2014/07/sterodealersinc-front-Seattle.jpg

http://www.taihs.org/wp-content/uploads/2014/07/stereodealersinc-back-Seattle.jpg

Ed

 

[oldphaser]

Coffee Can Amplifier

I spoke to him about it a number of years ago. There are a variety of different stories I have heard from people that were at the McIntosh clinics or knew Bob at the time. Some people say it exists some people say it doesn't. Some people say it refers to an open chassis. Others say it was a coffee can full of blown output transistors that were accumulated while Bob was designing the original 700. Some say it was kicking around for a while as a door stop. I have seen photos of a coffee can amp in a brand new Folgers coffee can. Needless to say, I will check into the "coffee can" story more for you.

I found this posted by Dave Ladely on December 19, 2015: http://www.audiocircle.com/index.php?topic=139506.0

Here is what Dave Ladely had to say:

"I have been involved with audio/video since 1965, with Bob Carver. Bob built an amplifier for me with parts i chose and purchased. The amp weighed about 130 pounds, was on three chassis (stereo channels and separate power supply). This very large tube amp, built in late 1966, was far more powerful than the most powerful consumer amps available (McIntosh 275 and dual Marantz Model 9s). Bob and I took it to the McIntosh Clinic when it came to the Seattle area, at Seattle Stereo. The amp blew all the others away. This inspired Bob to build a solid state version, came up with the name Phase Linear in 1967. Bob began building his first solid state Phase Linear 700 amps in 1969, in a house located on 3rd avenue in the north Shoreline area. He soon moved to a larger house on 25th Avenue in the nearby Richmond Beach area, where he continued building Phase Linear 700 amps. In January, 1970, Bob brought a complete amp to the McIntosh Clinic, where it tested at a bit over 350 watts RMS/channel, with very low distortion across the audio frequency band. The story about the "coffee can" amp is not at all true. Bob showed me the amp shortly afterward, along with the report. Bob has humorously went along with this myth, even on Utube, as it makes a good story, but all anyone has to do is read the McIntosh report to verify that they tested a production Phase Linear 700. Anyway, there is no way a 700 watt RMS amp would fit in any coffee can. Get real. Not long afterward, Bob sent a sample to Hirsch-Houck Laboratories to be tested. Audio Magazine published Julian Hirsch's report, where he found that the near universal assumption that 175 watts was "more than enough power for any home" to accurately reproduce any music on any system was not true. He found that his test of Horowitz on the piano required around 500 watts RMS for low distortion, realistic reproduction. After that report, demand for Phase Linear 700 watts suddenly increased until more Phase Linear amps were sold than McIntosh and Marantz combined. Phase Linear was sold to Pioneer in the early 1980s, but, without Bob as designer, the company foundered. At present, I am helping Bob with his new Amazing Line Source speakers, which are just getting into production."


NOTE: The history may be off a little.

The McIntosh clinic was January 15, 1971 at Seattle Stereo Center

Pioneer acquired Phase Linear in August 1978

The address was 19555 23rd N.W.





Ed

 

[laatsch55]

Well, that settles that....

 

[Northwinds]

I am crushed, no coffee can amps

 

[laatsch55]

Folgers fails again.

 

[BubbaH]

https://youtu.be/hMa1yH5QCxk