F1 poweramp to F1 preamp.
I have just finish converting F1 Poweramp to F1 preamp . It quite simple. First pump up the supply to 60V +- . Add some blocking caps to the out put, change some resistors value change the power mosfets and you will have the very quiet preamp. Mr. Pass knows that most of his poweramp design can be converted to pre amps. With Mr. Pass blessing I will finish details of my conversion. That it for now back to my music again.
I have just finish converting F1 Poweramp to F1 preamp . It quite simple. First pump up the supply to 60V +- . Add some blocking caps to the out put, change some resistors value change the power mosfets and you will have the very quiet preamp. Mr. Pass knows that most of his poweramp design can be converted to pre amps. With Mr. Pass blessing I will finish details of my conversion. That it for now back to my music again.
F1 p/amp 2 Pre/amp
Thank You Mr. Pass , JP Flemming is going to be a very happy guy.
First remove, R16 , R20, R29, R30, P2, Led1, R13, R14. R9 to R12 is remove an link together to drive of Q7.
Change : IRFP9240 to 9610, IRFP240 to 610.
Change : R27 & 28 to 15R 1W, R25 & 26 to 1K 1/4 W, R17 &18 to 27k 1/4 W, R7 & 8 to 68K 1/4 W, R5 & 6 to 30K 1/4W.
Change of position for P1 & R 15. = Place P1 and R15 in ground line, add 1K resistor to Gate Q7. Its just flipping over the components to ground line. (note R16 is remove.)
For input ;C1 & C2 value is 10u, add 15K after C1 & C2. R3 & R4 place at Gate of Q1 & Q2 . Z1 & Z2 add another piece of the same value back to back . Refer to Nelson pass past project for details.
Output ; place 10u caps at output add 100K to ground and 221R output resistant.
Power supply: Use 60Vdc.
Checking voltage; voltage between Q1 drain & Q2 drain is 30V . Oops P1 is 10K and R15 is 2K7 . Trim P1 to set voltage . Voltage at Q1 gate is 9V1 and at gate of Q7 is 4V1. At source of Q2 and drain of Q7 is 5V3.
That its for now i will let u know how its sound through Aleph 5. back to the music cannot get enough of it....
Thank You Mr. Pass , JP Flemming is going to be a very happy guy.
First remove, R16 , R20, R29, R30, P2, Led1, R13, R14. R9 to R12 is remove an link together to drive of Q7.
Change : IRFP9240 to 9610, IRFP240 to 610.
Change : R27 & 28 to 15R 1W, R25 & 26 to 1K 1/4 W, R17 &18 to 27k 1/4 W, R7 & 8 to 68K 1/4 W, R5 & 6 to 30K 1/4W.
Change of position for P1 & R 15. = Place P1 and R15 in ground line, add 1K resistor to Gate Q7. Its just flipping over the components to ground line. (note R16 is remove.)
For input ;C1 & C2 value is 10u, add 15K after C1 & C2. R3 & R4 place at Gate of Q1 & Q2 . Z1 & Z2 add another piece of the same value back to back . Refer to Nelson pass past project for details.
Output ; place 10u caps at output add 100K to ground and 221R output resistant.
Power supply: Use 60Vdc.
Checking voltage; voltage between Q1 drain & Q2 drain is 30V . Oops P1 is 10K and R15 is 2K7 . Trim P1 to set voltage . Voltage at Q1 gate is 9V1 and at gate of Q7 is 4V1. At source of Q2 and drain of Q7 is 5V3.
That its for now i will let u know how its sound through Aleph 5. back to the music cannot get enough of it....
Missing link.
Before u get all excited, I left out one very critical area. I send my son to night classes and forget all about it in the process. Remove C4 and R19. Split open Q5 & Q6 add 4K75 to R23 & R24 and ground it. Place 47uF caps on +60vdc line pos. to + voltage and - to R23 and 4K75. That it.
Volume control use 20k log at input. You can also add 10K lin. for balance control .
Flemming JP go ahead and built it u will put all your other preamps away for good.
Before u get all excited, I left out one very critical area. I send my son to night classes and forget all about it in the process. Remove C4 and R19. Split open Q5 & Q6 add 4K75 to R23 & R24 and ground it. Place 47uF caps on +60vdc line pos. to + voltage and - to R23 and 4K75. That it.
Volume control use 20k log at input. You can also add 10K lin. for balance control .
Flemming JP go ahead and built it u will put all your other preamps away for good.
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