Re: garAM10BC build thread
« Reply #20 on: June 14, 2018, 04:53:58 PM »
It would be best to see them somehow. What about the 620k resistor question?

Gary, Antonio thinks he received 620k R's instead of the 62k's. Can you shed some light on this?

Hey Jeff, I think I may have mistaken the red multiplier for orange when I reached out previously (didn't have my magnifying glass handy). I saw the 61.9k resistor in the assembly guide photo and assumed because the 62k color code didn't match that I mis-measured the original resistor by a decimal. I have since pulled out these resistors and re-measured them, so it looks like they are the correct 62k values. I do know that the distortion is not due to any diodes being polarized wrong, D6 and D7 look right to me. It does sound like a bias issue of some sort. Here's a link to photos of one of my builds:
https://www.dropbox.com/sh/npbomgfsa9do5tt/AADtdFwrlxjrlW3Mi69PO3Eza?dl=0

Thanks!


Potato Cakes

Re: garAM10BC build thread
« Reply #21 on: June 14, 2018, 07:30:38 PM »
D6 and D7 are incorrect. You made the same mistake that I posted about earlier in this thread. The PCB is marked properly, it's just that there are assumptions being made about placement and we all know that does... The instructions do clearly show proper orientation and there is even a photo of what it should look like. You can even see in your top photo that the line showing how the diodes are supposed to go. I did the same thing but didn't catch it till after I had ten of them finished.

Side note to Gary: don't change in the manual. It's perfectly fine the way it is unless you make a revision change to the design in the future. Also, thanks for this project!

Everyone else: please learn from my mistake that I wrote about on the first page of this thread. Double check the orientation of D6-8.

Thanks!

Paul
« Last Edit: June 14, 2018, 07:47:12 PM by Potato Cakes »

jsteiger

Re: garAM10BC build thread
« Reply #22 on: June 14, 2018, 07:41:53 PM »
...I do know that the distortion is not due to any diodes being polarized wrong, D6 and D7 look right to me.
As potato cakes Paul has stated, D6 and D7 are installed wrong. They are not polarized backwards but you have criss-crossed their holes. Take a closer look at the build guide. As Paul says, it is very clear.
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Re: garAM10BC build thread
« Reply #23 on: June 14, 2018, 07:57:13 PM »
Haha well this is embarrassing  :P I'll take another look. Thanks for the insight!
D6 and D7 are incorrect. You made the same mistake that I posted about earlier in this thread. The PCB is marked properly, it's just that there are assumptions being made about placement and we all know that does... The instructions do clearly show proper orientation and there is even a photo of what it should look like. You can even see in your top photo that the line showing how the diodes are supposed to go. I did the same thing but didn't catch it till after I had ten of them finished.

Side note to Gary: don't change in the manual. It's perfectly fine the way it is unless you make a revision change to the design in the future. Also, thanks for this project!

Everyone else: please learn from my mistake that I wrote about on the first page of this thread. Double check the orientation of D6-8.

Thanks!

Paul

JW

Re: garAM10BC build thread
« Reply #24 on: June 20, 2018, 01:16:41 PM »
Great sound to these! I have them in my master buss of my Yamaha PM2000 console and they're sweet sounding. Haven't listened critically enough to make comparisons to other opamps. But first impression is very sweet and smooth.


 

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