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What was the build year of my PL 400?
- Thread starter silver_face
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I'm interested to learn from the experts too.
I have a 4 fin PL400 with SN 343-323 and I was informed:
First digit = month
2nd digit = first numeral in power amp model number
3rd digit = last number of build year
The 3 number suffix denoted it's spot in the production run for that month.
In my case, the 323rd PL400 amplifier built in March of 1973.
Maybe your example, with 4 digits and no hyphen, means a different numbering system was in place?
As it happens, I also have a 700B (too heavy and awkward to move at the moment) and the original board was date stamped May, 1974. I've intended for some time to have a look at the SN just to see if it's SN fits the formula.
I have a 4 fin PL400 with SN 343-323 and I was informed:
First digit = month
2nd digit = first numeral in power amp model number
3rd digit = last number of build year
The 3 number suffix denoted it's spot in the production run for that month.
In my case, the 323rd PL400 amplifier built in March of 1973.
Maybe your example, with 4 digits and no hyphen, means a different numbering system was in place?
As it happens, I also have a 700B (too heavy and awkward to move at the moment) and the original board was date stamped May, 1974. I've intended for some time to have a look at the SN just to see if it's SN fits the formula.
In June 1974 Phase Linear went away from a date coded serial number to serial numbers starting at 1000.
More than likely your amp was made sometime in early 1975 (a few months) after the XPL909 transistors were made.
The 7452 on the XPL909's indicates the year 1974 and 52 would be the 52nd week or the last week of 1974.
Ed
More than likely your amp was made sometime in early 1975 (a few months) after the XPL909 transistors were made.
The 7452 on the XPL909's indicates the year 1974 and 52 would be the 52nd week or the last week of 1974.
Ed
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As a follow up to a more recent post, here is some additional information.......
Although the date "February 1976" appears on the top of page 1......
Please note that the serial numbers on page 2 of the image below only reflects those that were "still covered under the 3 year warranty program". This doesn't appear to jive with the "February 1976" since there are some dates from November 1972 on page 2.
It is unfortunate that we do not have the production number history for each month of the original 700 going back to when it first when into general production in February 1971. NOTE: 700's were actually being made before February 1971 and used either no serial number at all or a number stamped vertically on the transformer end bell. These amplifiers should all have a Seattle, WA sticker on them. This also includes the "bridge amp" and Kelly DeYong amps built in 1970. With the exception of the approximately (3) bridge amps that were built, most if not all of these amps only (built before approximately February 1971) had (12) output transistors along with (4) drivers (like a Phase Linear 400 had). Hence they were not very reliable. They may even also had 70 degrees C thermal cut-outs as opposed to the later units which had 90 degrees C thermal cut-outs. So the amps also thermally cycled more often.
The very early Phase Linear 700 series 1 "bridge amps" had (16) transistors mounted on the heat-sinks like other early 700's. However, I do not know if this version used drivers or not. I have the only known survivor and I don't think it had the original outputs on it when I bought it. As many early 700's had the original transistor numbers removed to prevent copying Bob Carver's design. Bob told me that he was using Motorola transistors on them at that time. No known schematic exits either for this amp.
I have posted pictures of the bridge amp and Kelly DeYong amps elsewhere on this forum.
Ed
Although the date "February 1976" appears on the top of page 1......
Please note that the serial numbers on page 2 of the image below only reflects those that were "still covered under the 3 year warranty program". This doesn't appear to jive with the "February 1976" since there are some dates from November 1972 on page 2.
It is unfortunate that we do not have the production number history for each month of the original 700 going back to when it first when into general production in February 1971. NOTE: 700's were actually being made before February 1971 and used either no serial number at all or a number stamped vertically on the transformer end bell. These amplifiers should all have a Seattle, WA sticker on them. This also includes the "bridge amp" and Kelly DeYong amps built in 1970. With the exception of the approximately (3) bridge amps that were built, most if not all of these amps only (built before approximately February 1971) had (12) output transistors along with (4) drivers (like a Phase Linear 400 had). Hence they were not very reliable. They may even also had 70 degrees C thermal cut-outs as opposed to the later units which had 90 degrees C thermal cut-outs. So the amps also thermally cycled more often.
The very early Phase Linear 700 series 1 "bridge amps" had (16) transistors mounted on the heat-sinks like other early 700's. However, I do not know if this version used drivers or not. I have the only known survivor and I don't think it had the original outputs on it when I bought it. As many early 700's had the original transistor numbers removed to prevent copying Bob Carver's design. Bob told me that he was using Motorola transistors on them at that time. No known schematic exits either for this amp.
I have posted pictures of the bridge amp and Kelly DeYong amps elsewhere on this forum.
Ed
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Ed, do you know the approximate month/year that the last PL700B, PL700 Series II, PL400, and PL400 Series II were built by Phase Linear for sale to the public (disregarding employee models and parts kits at the end of production)?
I can find no records of such information. And thanks to you for your valuable contributions to our site.
I can find no records of such information. And thanks to you for your valuable contributions to our site.
I have a PL400 with S/N 1043-225A. I have heard several variations on the A designation.
One was that A showed the amplifier was ordered by an employee.
Another legend was that the A fixed a duplicate serial number.
Lastly, I heard the A meant that the amplifier had to go through rework, but finally passed inspection.
Old Phaser would know.
One was that A showed the amplifier was ordered by an employee.
Another legend was that the A fixed a duplicate serial number.
Lastly, I heard the A meant that the amplifier had to go through rework, but finally passed inspection.
Old Phaser would know.
