New Stasis front end
- Thread starter Nelson Pass
- Start date
I was going to suggests putting trimpot locations on both edges but didn't think that was easily doable with all of the other traces on the boards. I suppose you could use jumpers to go over the other traces and decide which trimpot location you want to be in use.Hi Zen Mod, I don't know what size your FE boards were. The one Nelson laid out was 3.5"x5.5", which put it in the $65 with shipping for 10 pieces.
Hi Mike, I don't think I can change the gerbers from another package though I have never tried to import them (maybe I will have to look into that), I just use the schematic capture and PCB layout program to make new boards. On the new board I am making, it fits between the current long screws which are on a 2.75"x 4.25" pattern. I laid out the PCB to use the 220uf Silmics for C2 and C3. Also I like to use multiturn pots that can be had with the screw on the top or on the side, and you can reverse them, so they can face up or down, and I always try to put them near the edge of the board so easier to adjust, and if possible make a location on both edges so you populate whichever one you want up. I design stuff from the point of easier to service if I can. Too many times working on my car I wanted the Toyota engineers throat in my hands.
I have a LS400. Someday it will need a Timing belt... Was easy doing it on a Tundra but the LS400 is very tight... BTW, ford and Chevy are far worse.
So going back to my post in #1257 I learned a few things. I believe the NTC thermistor takes the bias and lowers it as the transistors come up to temp. I also learned that my bias issue was due to C4 being empty. As of right now, I have 20pf in there.
Increasing R18 resulted in very high bias, to the point where it would blow the negative rail fuse (I put 2 amp fuses in for testing). Lowering R18 resulted in lower bias and less of a rise. With 20pf oscillator cap in place, the bias behaves. Also, taking the cover off causes the bias to drift. So as Zen Mod says, put the amp together. I believe I need to increase C4 a bit more. I will grab a 25pf, 30pf and a 35 and try them. I need to get something that produces an accurate square wave though. At 10khz, my DAC seems to put out a sine wave according to my oscilloscope.
I also was able to fit the 220uf Silmic II cap in C2. I just bent it over.
When I get everything wrapped up. I will post a schematic with the values that I have in place. Also pictures showing everything as best as I can.
Now that I have the amp behaving a bit more, I put in my system and gave it a listen, the amp is extremely detailed.
Increasing R18 resulted in very high bias, to the point where it would blow the negative rail fuse (I put 2 amp fuses in for testing). Lowering R18 resulted in lower bias and less of a rise. With 20pf oscillator cap in place, the bias behaves. Also, taking the cover off causes the bias to drift. So as Zen Mod says, put the amp together. I believe I need to increase C4 a bit more. I will grab a 25pf, 30pf and a 35 and try them. I need to get something that produces an accurate square wave though. At 10khz, my DAC seems to put out a sine wave according to my oscilloscope.
I also was able to fit the 220uf Silmic II cap in C2. I just bent it over.
When I get everything wrapped up. I will post a schematic with the values that I have in place. Also pictures showing everything as best as I can.
Now that I have the amp behaving a bit more, I put in my system and gave it a listen, the amp is extremely detailed.
Quick question for you vets, using a 800va transformer with maybe ~300mf of capacitance on a CLCLC, is a thermistor like a cl60 or cl80 cool or should a thermistor be avoided and the store soft start board be used? I actually may have time to resume building this bad boy. Something that should have been a weekend build has turned into year long endeavor
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For managing in-rush current for a transformer and capacitance bank of that size, a larger thermistor will be necessary. I recommend the Ametherm MS22 20005. It has a higher initial resistance and greater current handling capacity. Also more surface area to manage the power dissipation.