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Sutt's "Fugly One" WOPL Transformation
- Thread starter jbeckva
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Be careful with that 480...
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Sutton, do you have a watt meter or a clamp-on ammeter? I am curious to know how many Amps a "hot" WOA'd PL700 will draw at max pull. I know there is a momentary rush, but at 510 Watts per channel, I wonder what the current draw really is. Mine with a Rev A board maxed at 12 Amps at the wall outlet.
There may be some math can can calculate +/- 105 Volts (that's 210 Volts DC) rail voltage into amps, but it will read that at idle. I think you really need to have the speakers thumping to get a max Amps measurement.
There may be some math can can calculate +/- 105 Volts (that's 210 Volts DC) rail voltage into amps, but it will read that at idle. I think you really need to have the speakers thumping to get a max Amps measurement.
I posted the following a little while ago:
A Phase Linear 700 series II amplifier; single channel driven at 1kHz into 8 ohms at 1% THD should be around 510-515 watts. Both channels driven at 1kHz into 8 ohms at 1% THD should be around 440 watts. Both channels driven at 1kHz into a 4 ohm load at 1% THD will be close to 700 watts. NOTE: According to my Monster Power AVS2000 display indication; under the conditions noted above for both channels driven into 8 ohms, the current draw is around 9.82 amps, and for 4 ohms is around 16 amps. NOTE: For both channels driven into a 4 ohm load you will need to increase the line fuse from 10 amps to at least 15 amps and the line supply cord should be 15 Amps as well. (NOTE: I have seen some modified 700 series amps with 10A line cords installed.) Fortunately the ABC15 fuse I used did not blow during this round of tests. The AGX fuses will also need to be increase from 5 amp to 8 amps as well. When testing at 4 ohms, particularly at 20kHz you run the risk of blowing the Zobel network resistors which are (2) 2 watt 10 ohm resistors in parallel for an effective 5 ohms. Clair Brothers discovered this themselves and insisted that Phase Linear use 5 ohm 50 watt resistors.
ED
A Phase Linear 700 series II amplifier; single channel driven at 1kHz into 8 ohms at 1% THD should be around 510-515 watts. Both channels driven at 1kHz into 8 ohms at 1% THD should be around 440 watts. Both channels driven at 1kHz into a 4 ohm load at 1% THD will be close to 700 watts. NOTE: According to my Monster Power AVS2000 display indication; under the conditions noted above for both channels driven into 8 ohms, the current draw is around 9.82 amps, and for 4 ohms is around 16 amps. NOTE: For both channels driven into a 4 ohm load you will need to increase the line fuse from 10 amps to at least 15 amps and the line supply cord should be 15 Amps as well. (NOTE: I have seen some modified 700 series amps with 10A line cords installed.) Fortunately the ABC15 fuse I used did not blow during this round of tests. The AGX fuses will also need to be increase from 5 amp to 8 amps as well. When testing at 4 ohms, particularly at 20kHz you run the risk of blowing the Zobel network resistors which are (2) 2 watt 10 ohm resistors in parallel for an effective 5 ohms. Clair Brothers discovered this themselves and insisted that Phase Linear use 5 ohm 50 watt resistors.
ED
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Ed, I read what you had posted earlier and I was interested in the current draw difference between a stock PL700 (Series I or II) and a WOA'd PL700 Full Comp. That would be a good measure of brute force between the two units. I am a little late to the WOA Full Comp party, so I am in firehose learning mode...
Unless you feel that your baseline testing above would show a negligible difference to the 'hot' amp that Sutton now has.
As far as the cords go, if during static or dynamic musical load testing, if the cord ever feels warm; it is time to increase the wire size/decrease the wire gauge. I imagine a PL700 at moderate to high power levels (touching red) into a 4 Ohm load would get warm after a while...
Unless you feel that your baseline testing above would show a negligible difference to the 'hot' amp that Sutton now has.
As far as the cords go, if during static or dynamic musical load testing, if the cord ever feels warm; it is time to increase the wire size/decrease the wire gauge. I imagine a PL700 at moderate to high power levels (touching red) into a 4 Ohm load would get warm after a while...
Mark,
I did some testing on (2) 700 series 2 amplifiers that Don G. owns. Both have a fully complementary output. One was a WOPL with a rev E board. The other was a Phase Linear (Clair Brothers) 700 series 2 amp. The Clair Brothers had a PL-36 pc board with a factory low distortion mod (which pretty much eliminates the crossover notch and greatly reduces distortion particularly at lower volume levels). This mod is not documented in Phase Linear 700 series II service manuals or service bulletins. The mod is very similar to what is in the 300 series 2 amps.
I also did some testing on a Phase Linear 700B w/ PL-20 pc board which is quasi complimentary.
The power consumption (both channels driven) at 1kHz and 1% THD was: 9.7-9.8 amps for the (2) 700 series 2 amps and 10.0 amps for the 700B.
Unless the transformer has B+ and B- voltages which are higher than normal, you will not see much difference. Typical B+ and B- for a 700 series 2 is around 102.6 to 102.9 VDC. That is with an input voltage of 120 VAC+/-1%. The 700B I tested had a B+ and B- of 104.0 VDC. A reasonably sized variac is also in order. Particularly if you are driving both channels to rated output into a 4 ohm load. I might even suggest 20A for extra margin and reduction in sag. Currently I have one Variac rated at 15A and the Monster Power rated at 25A (3000W)
The power cords Phase Linear originally used were rated for 15A. There are some WOPL'd amps out there whereby the power cords were replaced with 10A cords.
"Brute force" is not necessarily a term I would be using. Efficiency would be.
Ed
It is all elementary my dear Mr. ( insert name),
I am thrilled to have the best power amp I have ever heard, and forget all the upgrade path (other brand marketing stuff) crap....knowing that, if Joe hasn't upgraded to a new version you probaly have the finest power amp ever made. I felt that way in 1974 when I bought my first PL 400 (until it started blowing up and taking my sprakers with it)....
Joe has now made this the finest amp available anywhere, at any cost ....in my opinion...
I am thrilled to have the best power amp I have ever heard, and forget all the upgrade path (other brand marketing stuff) crap....knowing that, if Joe hasn't upgraded to a new version you probaly have the finest power amp ever made. I felt that way in 1974 when I bought my first PL 400 (until it started blowing up and taking my sprakers with it)....
Joe has now made this the finest amp available anywhere, at any cost ....in my opinion...
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