Bob's 4 WOPL 400 builds

Gepetto

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audiobob said:
Hi Joe, yes I connected the 10K resistors, one each to each channel, with nothing connected to the DC output board except for a couple grounds. The resistors are connected via alligator clip leads. I'm going to try using a small contact block and see if that helps.
Click to expand...
Meaning you connected one end of each 10K ohm resistor to the backplane board test point labeled Output and the other end of the resistor to the backplane board test point labeled GND? that is where these have to go when you have a DC Protect circuit in place.
 
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Success! Got rid of the alligator leads and hooked up to a terminal block and I never went over a millivolt when bringing it up. The alligator clips were cheepees and may not have given very good connections. Caps to 80V + and - with no problems observed. Now to finish the build.
 
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Gepetto said:
Meaning you connected one end of each 10K ohm resistor to the backplane board test point labeled Output and the other end of the resistor to the backplane board test point labeled GND? that is where these have to go when you have a DC Protect circuit in place.
Click to expand...
Actually connected the OUT2 L and R with a 10K each to the two white wires that go to the common chassis ground. My problem I think was that I was using crapy alligator leads that probably gave me more than 10K of resistance. The only thing I did was replace the alligators with the hardwire (so to speek) terminal block for a good connection. No more than 1mV each channel through the whole process of increasing the voltage. Total VDC at the caps was 160V. Going to final build now.
 
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Thanks Lee. I thought it fit right in here. Say, I seem to have a problem with my bias adjustments. I have 6mV on the left and 22mV on the right bias test points to the input minus per the procedure and those numbers don't change when adjusting the pots full range. I can't seem to figure this out. I do have my 15VDC +/-. On my PL14-20 Rev E board I did not install R36 because it said on the package (quasi comp only) for R36. Could you or Joe help me out on this. Just can't seem to nail it on cause?
 
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Also, make sure the bias transistor is in the 2N5088 holes instead of the 2N3403 holes, I've done it and it will screw up the bias...
 
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Well that was it. I some how flew right over R36 in the BOM and on the package of 1 ohm 1/4 watt resistors during the build. In stalled the resistors in R36 and was able to adjust both. Thanks again Lee. Can't wait to hear this one tomorrow.
 
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Coolness Bob.....you'll be amazed....you now own one of the finest amps on the planet...
 
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audiobob said:
Well that was it. I some how flew right over R36 in the BOM and on the package of 1 ohm 1/4 watt resistors during the build. In stalled the resistors in R36 and was able to adjust both. Thanks again Lee. Can't wait to hear this one tomorrow.
Click to expand...
Hi Bob
Sorry for not being online yesterday. I went back and double checked the documentation and it appears correct on the labels and on the BOM. Is there something I can do to make this clearer in the docs? Let me know.

Thanks
Joe
 
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IMG_2244.jpg IMG_2247.jpg IMG_2248.jpg IMG_2251.jpg IMG_2253.jpg

Finally got the first one done. This thing sounded great last night. Indeed no hiss or any sound coming from the speakers at full volume. I had my Anthem D1 hooked up for the preamp and gave a listen to Allen Parson's Project Turn of a Friendly card and David Templton's Never in a lifetime as well as a mix of others. Oh how sweet! Very nice upgrade from the ADCOM GFA-7400 which wasn't a bad amp, it just doesn't have the giddy up and I believe the detail the the WOPL 400 gave me last night. Could only play at half volume as the amp beyond that was to much for my ears. Was powering a couple Manapan MG-12QR for now till I finish the rebuild of the Magnapan MG-IIIa speakers. Unfortunately can't say anything about the base due to the fact that that I have the Miller & Kreisel MX-80 and 125 MKII active subs. The MG-12QR only goes down to 45Hz but with the subs turned off the Magies still pumped out some great sound. Now for the unfortunate part. After playing for about 3 hours last night the sound cut out at about 1/3rd volume. The VU meters were moving to beat the band but no sound so something happened to the DC protect board I think. Will check it out when I get home tonight. Very nice Joe. The WOPL indeed is worth the time and money put in to it.
 
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The DC protect will sometimes nuisance trip if a lot of low end material is played at high volume. Also check rail fuses. To reset the DC protect board cycle ac power.
 
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Gepetto said:
Hi Bob
Sorry for not being online yesterday. I went back and double checked the documentation and it appears correct on the labels and on the BOM. Is there something I can do to make this clearer in the docs? Let me know.

Thanks
Joe
Click to expand...
RED ink worked for me!!! LOL!!
 
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To those who weren't privy to that little fact, the red ink in the BOM's about not drilling out the wire holes on the bottom of the driver boards is because I drilled out the wire holes on a couple boards and had some real bad intermittent problems on those boards....
 
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audiobob said:
Finally got the first one done. This thing sounded great last night. Indeed no hiss or any sound coming from the speakers at full volume. I had my Anthem D1 hooked up for the preamp and gave a listen to Allen Parson's Project Turn of a Friendly card and David Templton's Never in a lifetime as well as a mix of others. Oh how sweet! Very nice upgrade from the ADCOM GFA-7400 which wasn't a bad amp, it just doesn't have the giddy up and I believe the detail the the WOPL 400 gave me last night. Could only play at half volume as the amp beyond that was to much for my ears. Was powering a couple Manapan MG-12QR for now till I finish the rebuild of the Magnapan MG-IIIa speakers. Unfortunately can't say anything about the base due to the fact that that I have the Miller & Kreisel MX-80 and 125 MKII active subs. The MG-12QR only goes down to 45Hz but with the subs turned off the Magies still pumped out some great sound. Now for the unfortunate part. After playing for about 3 hours last night the sound cut out at about 1/3rd volume. The VU meters were moving to beat the band but no sound so something happened to the DC protect board I think. Will check it out when I get home tonight. Very nice Joe. The WOPL indeed is worth the time and money put in to it.
Click to expand...
Very pretty work Bob, looks like you have done this before. Glad you made it through the last steps and got to listen to some music through the amp (for a while anyway :))

I am sure you will find your way through the last issue, seems you have it narrowed down.
 
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