I will try to post better scans of the schematic and layout after work today as well. I also have a a copy of a High FI newsletter from 1972 that reports on a shoot out between the Crown DC300 and original PL model 700, entitled "Battle of the Giants". Prices listed for these back then were $779 for the PL and $685 for the Crown. I believe that is about a third the price of a car back then. Regarding the shootout, can you guess which one won?
Netlist said:
One of the reasons I would like to clone this amp, as I used to own some dimmer racks of theirs, so it would be nice to make up the set. 🙂
Ok, so which one. Hugo seems to be voting for the Mk1, any other preferences? Anyone have any BOMs? That might make substitution a little easier.
I vote 700B early or later version.
I believe it has improvements over the first design, less parts and doesn't use the opamp.
I must have a BOM somewhere...
/Hugo
I believe it has improvements over the first design, less parts and doesn't use the opamp.
I must have a BOM somewhere...
/Hugo
I vote 700A (I have 2). Original and the best of the 3. A and B are very close to the same and both have no opamp. I do have the BOM and will post asap.
Netlist said:
I'd avoid the OpAmp version too. The board looks like &@#$ so I don't think it is worth copying. If the schematic(s) are true then it would be better to cut a fesh design/layout. Then any transistor changes can be embraced much easier. Perhaps the same physical foot print of the board for drop in replacement? Perhaps some open portions on the PCB but that could be a cut out/break off piece or ground plane?
Am I making sense today?
I don;'t ever recall hearing these amps though I'm certain I have at many live venues. I didn't have any chums that used Phase Linear and my guess would be that they had no or little representation on the East Coast. Who knows?
Cheers,
Shawn.
Gibbi said:
To make sure I understand correct; We have 700, 700B early, 700B later and 700II opamp.
I'm really not sure which one you prefer.
/Hugo
.
By 700A I am referring to the original 700. As for the 700B, I was not aware there were two versions of that one.
The site link is great, I have never seen that one before.
By 700A I am referring to the original 700. As for the 700B, I was not aware there were two versions of that one.
The site link is great, I have never seen that one before.
I've got PDF's of all of the serivce manuals for the 400, 400II, 700/700B, and 700II. Send me an email if you want it. I've got schematics and service bulletins on my web site. Not enough space for the whole manual.
Phase Linear site
The 400/700/700B were quasi comp. Later versions of the 400II and 700II were full comp. I've successfully converted a 400II quasi comp to full comp. I've got two 400's and two 700's that I plan to convert to full comp this winter.
The 400/700/700B uses hard to find germanium devices in the protection circuit. The II's used silicon devices. The circuits are very similar and it should be easy to modify the germaniums to silicon. I've got a PDF of the patent for the protection circuit on my site also. Very interesting reading.
Last year there was a guy who sold a series II board on EBAY. Yes, the series II has the opamp front end. He had the gerber files. I may be able to dig up his email address and see if he still has the files.
My experience has shown that some amps oscillate with new outputs. This seems to be most prevalent with the 2SD555's. I've not had any problems with the MJ2119X devices. I've been using them for about 18 months in 10-15 repairs.
Phase Linear site
The 400/700/700B were quasi comp. Later versions of the 400II and 700II were full comp. I've successfully converted a 400II quasi comp to full comp. I've got two 400's and two 700's that I plan to convert to full comp this winter.
The 400/700/700B uses hard to find germanium devices in the protection circuit. The II's used silicon devices. The circuits are very similar and it should be easy to modify the germaniums to silicon. I've got a PDF of the patent for the protection circuit on my site also. Very interesting reading.
Last year there was a guy who sold a series II board on EBAY. Yes, the series II has the opamp front end. He had the gerber files. I may be able to dig up his email address and see if he still has the files.
My experience has shown that some amps oscillate with new outputs. This seems to be most prevalent with the 2SD555's. I've not had any problems with the MJ2119X devices. I've been using them for about 18 months in 10-15 repairs.
Excellent, good to have you on board. I may be in touch later about the service manuals.
Personally I am thinking of the quasi variants, as I have never built one before, so it would be fun to have something different.
Personally I am thinking of the quasi variants, as I have never built one before, so it would be fun to have something different.
d3imlay,
If you were to choose from different versions, what would be your preferred one?
I mean sound wise, as you must have heard a lot of them.
One of the reasons why I like the 700B is that the one version doesn’t carry the big 15K power resistor anymore. (Which might of course have other disadvantages.)
Also, I wonder why the right channel has R2 2.7ohm and the left channel 56 ohm. (Phase?)
R61 seems to very greatly with different builds – 6.8k and 18k - (R between collectors of the diffpair), so does the feedback resistor - 12k and 39k - and the base R of Q1 – 2.7k and 10k. Care to elaborate a bit on these details?
/Hugo
If you were to choose from different versions, what would be your preferred one?
I mean sound wise, as you must have heard a lot of them.
One of the reasons why I like the 700B is that the one version doesn’t carry the big 15K power resistor anymore. (Which might of course have other disadvantages.)
Also, I wonder why the right channel has R2 2.7ohm and the left channel 56 ohm. (Phase?)
R61 seems to very greatly with different builds – 6.8k and 18k - (R between collectors of the diffpair), so does the feedback resistor - 12k and 39k - and the base R of Q1 – 2.7k and 10k. Care to elaborate a bit on these details?
/Hugo
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