Rare Phase Linear stuff

[laatsch55]

But still only 16 output devices....

 

[oldphaser]

Does he remember building it??

Either Bob Carver or Steve Johnston built it. No way to tell for sure. I also spoke to Steve a year or two ago about it and he said the same thing.
Very interesting story about how the amp came into existence which I hope to be able to tell a little later. Perhaps after I get a little rest and I get over all the excitement we had today. Stay tuned.

 

[laatsch55]

Interesting the outputs are oriented 90 degrees from later...

 

[laatsch55]

Dig you get to bring up the "coffee can" amp??

 

[oldphaser]

But still only 16 output devices....

Yep only (16) devices. Even the very early 700's built in 1971 with the PL0171 pc board only had (16) transistors. (12) outputs and (4) drivers. These early amps often times had no serial numbers on them.

The bridge amp had from what I can tell so far.... no drivers mounted to the heatsinks.
I am certainly no expert on this one yet. I hope to spend some more time with Bob and get to know this amp better.

It does not have the original output transistors which I had asked Bob about several years ago. He stated that they were Motorola transistors. I have installed GM/Delco DTS411's for the moment or until Bob gets a chance to review some of his old Motorola data sheets and tell me what the originals were.

 

[laatsch55]

Yep only (16) devices. Even the very early 700's built in 1971 with the PL0171 pc board only had (16) transistors. (12) outputs and (4) drivers. These early amps often times had no serial numbers on them.

The bridge amp had from what I can tell so far.... no drivers mounted to the heatsinks.
I am certainly no expert on this one yet. I hope to spend some more time with Bob and get to know this amp better.

It does not have the original output transistors which I had asked Bob about several years ago. He stated that they were Motorola transistors. I have installed GM/Delco DTS411's for the moment or until Bob gets a chance to review some of his old Motorola data sheets and tell me what the originals were.

I would hazard a guess it is not a paragon of low noise....

 

[oldphaser]

Dig you get to bring up the "coffee can" amp??

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.

 

[oldphaser]

I would hazard a guess it is not a paragon of low noise....

We did spend some time discussing safe operating area.

 

[laatsch55]

There is a post in the "Ask Ed " forum....if you wouldn't mind.....

 

[Gepetto]

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.

Looks like a lot of engineering changes by the look of the board backside...

 

[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!!