PL 700 II Clair Bros Rising from the Ashes
- Thread starter Peter S
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Yes, Beautiful amp Glen. The black face-plates are growing on me. Are new Series II face-plates available? I have been scratching my head all week about what is going with my noisy monster. I used the configuration "A" in the Henry Ott book for source grounded, load floating----and the result was disastrous.
Just before I posted another plea for guidance, I thought I would try connecting the input EXACTLY the way Joe suggests; Coax shield on pin 2, Hot on pin 1.......and strangely... it seems to work fine! I'm going to double check things tomorrow---why spoil the rest of the day. Now I feel like my Electrician buddy who had 5 sons; He said he couldn't follow a blueprint, even if he was lying on it.
Just before I posted another plea for guidance, I thought I would try connecting the input EXACTLY the way Joe suggests; Coax shield on pin 2, Hot on pin 1.......and strangely... it seems to work fine! I'm going to double check things tomorrow---why spoil the rest of the day. Now I feel like my Electrician buddy who had 5 sons; He said he couldn't follow a blueprint, even if he was lying on it.
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- Gillette, Wyo.
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- Halfbiass...Electron Herder and Backass Woof
Just retested residual noise with 1k jumper across input. This is with shielded ac And one end only of the shield conncted to the bus bar.
right channel .650 mv
Left channel .512 mv
the amp turns a true 465 watts into my 7.3 ohm load resistor single channel driven.
THD+N in unweighted setting
left .01%
Right .04%
the ac is unshielded on the right side from the power plug to the fuse.
these numbers are outstanding as they are real, no BS.
right channel .650 mv
Left channel .512 mv
the amp turns a true 465 watts into my 7.3 ohm load resistor single channel driven.
THD+N in unweighted setting
left .01%
Right .04%
the ac is unshielded on the right side from the power plug to the fuse.
these numbers are outstanding as they are real, no BS.
Glen,
At what frequency was the THD+N numbers taken at? Let me guess (1kHz). How about rated output at 20kHz?
What was the duration of test when you did the THD measurement?
You mention that it does 465 watts into a 7.3 ohm load single channel driven. At what frequency and THD+N?
Did you test the residual noise with the volume pots at CCW, 12 o'clock and fully CW? Did you also try this test after reversing the line cord?
Ed
Interesting questions Ed.
please post your results for me to compare for your build in this thread
https://forums.phxaudiotape.com/thr...-some-amps-phase-linear-white-oak-audio.8459/
please post your results for me to compare for your build in this thread
https://forums.phxaudiotape.com/thr...-some-amps-phase-linear-white-oak-audio.8459/
Glen
Pardon me for the following ramblings..... just putting some thoughts down...
Since you are posting incomplete specs, I thought I would ask you to elaborate further. Otherwise they are meaningless.
As an example:
THD+N in unweighted setting
left .01%
Right .04%
What does this mean without providing the frequency or range of frequencies (i.e. 20Hz to 20KHz) and output level? Whether it is single channel driven or both channels driven? Or the duration of test?
For more examples of specsmanship I refer you to Dennis Bohn's (former National Semiconductor, Phase Linear and Rane engineer) article on "Audio Specifications" for more examples:
https://web.archive.org/web/2015092...ne.com/pdf/ranenotes/Audio_Specifications.pdf
How about I post some data on an amp that was built by a well known WOPL builder as well as a Clair Brothers amp I built from scratch? This might cause some more threats to my life from this builder. I also have some data on many other Phase Linear 400 and 700 series amps. Each one took many days of writing down measurements, doing the math and formatting it into a Word document. The amount of time it will take to write down all the caveats (and measurement uncertainties) for each measurement before posting this on the internet will be time consuming. This is order to recognize where the shortcomings are and to avoid all the gotcha's (people may want to post) that will eventually follow.
I don't have all the data I want yet on some parameters, i.e. rise time, slew rate, IMD (SMPTE and CCIR), as well as DIM and tri-tone (developed by Bob Cordell at Bell Labs), etc. Frequency response at 1 watt out to 250Khz +0/-1dB is another condition I am interested in since the Phase Linear series 1 amps were spec'd out that far. My HP 239A (which I am going to sell) and my Krohn Hite 4402B as well as the 239A's that are built into my 339A's only go out to about 110KHz and my Leader function generator is only good to +/-1dB from 100KHz to 10MHz. I needed something more accurate for the frequency response tests so I recently bought a Krohn Hite function generator specifically for the frequency response test. It had a manufacturer's stated accuracy of 0.1dB from 0.2Hz to 300kHz. Unfortunately I had to return it to the ebay seller and now am in negotiation with a test equipment dealer for something else.
I purchased a Leader function generator with better rise time (to replace my old MITS function generator) as well a Krohn Hite 4402B ultra-pure sine wave signal generator which has a far better amplitude/level flatness as well as distortion level (typically less than .0005%). I need to send my Krohn Hite in for calibration/repair. My old Heathkit IM-5248 IM analyzer (which I've owned since 1979) is not meeting spec and thus needs repair. The old Heathkit IM-5248 also allows you to input other frequencies beside 60Hz and 7kHz. An IC upgrade is also in order to reduce the IMD on the IM-5248. I had a Sound Technology 1700 or 1710 series with the IM option 20 or so years ago. However, I sold it due to the concern of eventually repairing all the switches, etc.
Strangely enough I am also considering an old HP 334A (to add to my (2) HP 339A's) since it has a wider bandwidth (at 600KHz) than most of the other distortion analyzer's that only go out to 100 to 120Khz (like the ATS-1DD, 339A and 8903B). This will allow me to actually test an amplifier at 100kHz and measure a number of harmonics; H2, H3, H4, H5 and H6. NOTE: The Phase Linear 700HF's that were built for Bell Labs were spec'd out to 100kHz at .25% THD. NOTE: The duration of test was very short for this test, as I witnessed on Dean's HP 334A.
I acquired and old HP 3580 spectrum analyzer and HP 3562A dynamic signal analyzer in the past year. I intend to look at the harmonics individually. Looking for even order versus odd order as well as higher order harmonics for dissonance as I witnessed John Curl do.
I have been measuring AC leakage in accordance with an old version of an ANSI standard C101.1-1971 using an old VIZ WT-540B. The ANSI standard was revised a number of years ago to C101-1992 so I bought a Simpson 228 "Leakage Current Tester". This standard has been superseded by UL-101 but I don't want to spend the $631 to see what is different in its content.
More purchases are on the horizon. I have been in close communication with a number of well respected old audio gurus who have far more experience with audio test equipment and am always on the look out to expand/improve my capabilities.
More test equipment purchases is in the works. Quietly and secretly from my wife.
All the while, my wife is after me to sell off all the other stuff I have. I'd rather be working on the Phase Linear stuff.
Ed
Pardon me for the following ramblings..... just putting some thoughts down...
Since you are posting incomplete specs, I thought I would ask you to elaborate further. Otherwise they are meaningless.
As an example:
THD+N in unweighted setting
left .01%
Right .04%
What does this mean without providing the frequency or range of frequencies (i.e. 20Hz to 20KHz) and output level? Whether it is single channel driven or both channels driven? Or the duration of test?
For more examples of specsmanship I refer you to Dennis Bohn's (former National Semiconductor, Phase Linear and Rane engineer) article on "Audio Specifications" for more examples:
https://web.archive.org/web/2015092...ne.com/pdf/ranenotes/Audio_Specifications.pdf
How about I post some data on an amp that was built by a well known WOPL builder as well as a Clair Brothers amp I built from scratch? This might cause some more threats to my life from this builder. I also have some data on many other Phase Linear 400 and 700 series amps. Each one took many days of writing down measurements, doing the math and formatting it into a Word document. The amount of time it will take to write down all the caveats (and measurement uncertainties) for each measurement before posting this on the internet will be time consuming. This is order to recognize where the shortcomings are and to avoid all the gotcha's (people may want to post) that will eventually follow.
I don't have all the data I want yet on some parameters, i.e. rise time, slew rate, IMD (SMPTE and CCIR), as well as DIM and tri-tone (developed by Bob Cordell at Bell Labs), etc. Frequency response at 1 watt out to 250Khz +0/-1dB is another condition I am interested in since the Phase Linear series 1 amps were spec'd out that far. My HP 239A (which I am going to sell) and my Krohn Hite 4402B as well as the 239A's that are built into my 339A's only go out to about 110KHz and my Leader function generator is only good to +/-1dB from 100KHz to 10MHz. I needed something more accurate for the frequency response tests so I recently bought a Krohn Hite function generator specifically for the frequency response test. It had a manufacturer's stated accuracy of 0.1dB from 0.2Hz to 300kHz. Unfortunately I had to return it to the ebay seller and now am in negotiation with a test equipment dealer for something else.
I purchased a Leader function generator with better rise time (to replace my old MITS function generator) as well a Krohn Hite 4402B ultra-pure sine wave signal generator which has a far better amplitude/level flatness as well as distortion level (typically less than .0005%). I need to send my Krohn Hite in for calibration/repair. My old Heathkit IM-5248 IM analyzer (which I've owned since 1979) is not meeting spec and thus needs repair. The old Heathkit IM-5248 also allows you to input other frequencies beside 60Hz and 7kHz. An IC upgrade is also in order to reduce the IMD on the IM-5248. I had a Sound Technology 1700 or 1710 series with the IM option 20 or so years ago. However, I sold it due to the concern of eventually repairing all the switches, etc.
Strangely enough I am also considering an old HP 334A (to add to my (2) HP 339A's) since it has a wider bandwidth (at 600KHz) than most of the other distortion analyzer's that only go out to 100 to 120Khz (like the ATS-1DD, 339A and 8903B). This will allow me to actually test an amplifier at 100kHz and measure a number of harmonics; H2, H3, H4, H5 and H6. NOTE: The Phase Linear 700HF's that were built for Bell Labs were spec'd out to 100kHz at .25% THD. NOTE: The duration of test was very short for this test, as I witnessed on Dean's HP 334A.
I acquired and old HP 3580 spectrum analyzer and HP 3562A dynamic signal analyzer in the past year. I intend to look at the harmonics individually. Looking for even order versus odd order as well as higher order harmonics for dissonance as I witnessed John Curl do.
I have been measuring AC leakage in accordance with an old version of an ANSI standard C101.1-1971 using an old VIZ WT-540B. The ANSI standard was revised a number of years ago to C101-1992 so I bought a Simpson 228 "Leakage Current Tester". This standard has been superseded by UL-101 but I don't want to spend the $631 to see what is different in its content.
More purchases are on the horizon. I have been in close communication with a number of well respected old audio gurus who have far more experience with audio test equipment and am always on the look out to expand/improve my capabilities.
More test equipment purchases is in the works. Quietly and secretly from my wife.
All the while, my wife is after me to sell off all the other stuff I have. I'd rather be working on the Phase Linear stuff.
Ed
Last edited:
Glen,
It is a simple question. You already performed the measurement. So you should already know the answers. I'm not asking you to go back and perform any further measurements.
What frequency or range of frequencies (i.e. 20Hz to 20KHz) and output level did you use? Are the results noted below single channel driven or both channels driven?
As stated in your example:
THD+N in unweighted setting
left .01%
Right .04%
My guess is that the measurement is at 1kHz and not 20Hz to 20kHz. My guess also is that it is single channel driven and not both channels driven.
Ed
It is a simple question. You already performed the measurement. So you should already know the answers. I'm not asking you to go back and perform any further measurements.
What frequency or range of frequencies (i.e. 20Hz to 20KHz) and output level did you use? Are the results noted below single channel driven or both channels driven?
As stated in your example:
THD+N in unweighted setting
left .01%
Right .04%
My guess is that the measurement is at 1kHz and not 20Hz to 20kHz. My guess also is that it is single channel driven and not both channels driven.
Ed
Almost done!
The inputs have been wired with Coax to the input phone jacks. Phone jacks have ring and sleeve shorted together. With inputs shorted, there is about 1 & 1/2 mv P to P hum and noise L, 1 mV on R. With the amp connected to a grounded Leader signal generator, There is about 2, (maybe 2 & 1/2) mV P to P, on both chan. I can live with this, only audible with my ear an inch from the speaker, and the amp is wide open, no input pots.
One of the voice coils in my sacrificial speakers tried to escape yesterday when the RCA plug was not fully inserted into the signal generator. I think the amp wants to tell me there is still some 'Flame linear' left in it's blood!
The inputs have been wired with Coax to the input phone jacks. Phone jacks have ring and sleeve shorted together. With inputs shorted, there is about 1 & 1/2 mv P to P hum and noise L, 1 mV on R. With the amp connected to a grounded Leader signal generator, There is about 2, (maybe 2 & 1/2) mV P to P, on both chan. I can live with this, only audible with my ear an inch from the speaker, and the amp is wide open, no input pots.
One of the voice coils in my sacrificial speakers tried to escape yesterday when the RCA plug was not fully inserted into the signal generator. I think the amp wants to tell me there is still some 'Flame linear' left in it's blood!
Attachments
BTW Perry, I have to do my measurements with HVAC off. I have a Trane heat-pump that produces some noise on the line that obscures measurements when the scope is set to 0.5 mV per division.
Had the amp all back together and upstairs in the main sound system when I found that the Right chan was 10 db quieter than the left----Son-of--gun is what I should have said. As usual, my OCD got the better of me. I found some fancy coax with a braid as well as a foil shield, the best of both worlds according to Henry Ott. Unfortunately I did not realize that it also had a black layer of of something conductive that I mistook for insulation, it came in contact with the centre conductor on one channel and shunted the signal with about 2 k ohm.......If you learn from your mistakes, I should be a genius by now.
Since the amp was open, I thought I would post this pic; I have had issues with the power switches on a couple of amps, would this not be a valid preemptive measure?
Had the amp all back together and upstairs in the main sound system when I found that the Right chan was 10 db quieter than the left----Son-of--gun is what I should have said. As usual, my OCD got the better of me. I found some fancy coax with a braid as well as a foil shield, the best of both worlds according to Henry Ott. Unfortunately I did not realize that it also had a black layer of of something conductive that I mistook for insulation, it came in contact with the centre conductor on one channel and shunted the signal with about 2 k ohm.......If you learn from your mistakes, I should be a genius by now.
Since the amp was open, I thought I would post this pic; I have had issues with the power switches on a couple of amps, would this not be a valid preemptive measure?
