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Old 4th April 2011, 09:49 PM   #41
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Guess I will use what I have on hand for testing, then order the ones from the bom to swap out when they get here. I plan to shoot pix of the process, and post them on audiokarma.org. This was a request from a member there. Pete, you are welcome to use any of it for a manual if it helps. I will update with a link when I post it.
Again many thanks to your contributions to the Diy community,
Al Purcell
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Old 12th April 2011, 10:37 PM   #42
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How big of an improvement the $12 Radiodaze choke (or any similar Hammond or Triad choke) can make in this particular amp compared to the resistor? I have collected all the parts same as on the BOM. Yes, I understand a choke will sound better any how, but will this particular amp benefit greatly or just marginally from a choke?


Now the question about chassis..

Are the headphone jacks and potentiometer grounded on PCB? I'm thinking about using aluminum top plate bolted on a frame of wood, drilling the holes for headphone jacks and potentiometer on the front piece of wood. Speaker posts, RCA and IEC all will be mounted on the top aluminum plate. So, is it safe to use wooden front panel or the headphone jacks and pot must be grounded on a metal chassis like Hammond?
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Old 13th April 2011, 09:21 PM   #43
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Quote:
Originally Posted by imnewbie View Post
Are the headphone jacks and potentiometer grounded on PCB? I'm thinking about using aluminum top plate bolted on a frame of wood, drilling the holes for headphone jacks and potentiometer on the front piece of wood. Speaker posts, RCA and IEC all will be mounted on the top aluminum plate. So, is it safe to use wooden front panel or the headphone jacks and pot must be grounded on a metal chassis like Hammond?
The jacks are grounded on the PCB, and are actually insulated from the panel. So no problems there. The pot mechanicals (shaft, front) are not grounded to the PCB. You may or may not need to somehow ground this. Sometimes if you leave it ungrounded, especially with a metal knob, you will hear hum/noise when you bring your hand near the volume knob.

Pete
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Old 25th April 2011, 06:46 PM   #44
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What is JP1? Is it needed? It's not on the BOM
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Old 25th April 2011, 07:37 PM   #45
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Originally Posted by apurcell22 View Post
What is JP1? Is it needed? It's not on the BOM
Just a way to defeat the ground loop breaker and connect signal ground directly to AC ground. You probably will not need it.

Pete
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Old 25th April 2011, 07:51 PM   #46
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Thanks Pete. I should have this up and running today.
Al
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Old 27th April 2011, 12:26 AM   #47
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Pete
Just noticed that the board seems to be opposite what the conventional setup should be. Looks like you just swapped the inputs to the board. Is this correct?
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Old 27th April 2011, 02:37 AM   #48
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I completed the amp this afternoon. It sounds nice, except for the hum. I thought that this thing would be dead quiet with the added choke. I haven't taken any voltage readings yet, nor have I lifted the ground to see if that quieted things down. You can't hear it when the music is playing, only in quiet passages, but I am sure it will sound even better when the hum is gone.
Al
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Old 27th April 2011, 04:11 AM   #49
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Ok. Lifting the ground nor switching polarity made much of a difference. It made a little, but once I moved the volume pot a little, there it was.
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Old 27th April 2011, 03:56 PM   #50
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Quote:
Originally Posted by apurcell22 View Post
Ok. Lifting the ground nor switching polarity made much of a difference. It made a little, but once I moved the volume pot a little, there it was.
Is the hum still there when the pot is all the way down? If so, how far are the OPTs away from the power transformer and choke(s)?
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