hiwatt dr103 build presence control sweep
Posted: Sat Mar 05, 2022 1:36 am
I recently build a hiwatt dr103 clone that works fine and sounds awesome. I used this layout and referenced the schematics from hiwatt.org
http://www.ceriatone.com/ceriatone/wp-c ... hat103.jpg
with a few changes: No external bias jacks, HT wires on the opposite side, HT fuse between bridge and ground.
Here are some pics from the build
https://drive.google.com/file/d/1mhQqoG ... sp=sharing
https://drive.google.com/file/d/1a0t8QZ ... sp=sharing
https://drive.google.com/file/d/1jpJ5eQ ... sp=sharing
https://drive.google.com/file/d/157_fK9 ... sp=sharing
https://drive.google.com/file/d/17p0ozX ... sp=sharing
https://drive.google.com/file/d/1cRSzDA ... sp=sharing
https://drive.google.com/file/d/1qJF74Q ... sp=sharing
https://drive.google.com/file/d/1DmcOGR ... sp=sharing
https://drive.google.com/file/d/1MPQ5pK ... sp=sharing
The problem is that the sweep of the presence pot is not evenly distributed. seems like all changes are happening on the last quarter of the pot. no noticeable difference in the first 3/4 of the pot.
I have looked at a couple other schematics and noticed 2 variations:
lower filter cap from 100n to 47n
https://hiwatt.org/Schematics/DR_Pre4Input_v1a.gif
increased wiper resistance to ground from 100R to 470R
https://hiwatt.org/Schematics/DR_Pre4Input405.gif
My question is if any of these changes will make the sweep more usable and distributed across the pot without affecting the way the NFB works. and if not what else can be done.
http://www.ceriatone.com/ceriatone/wp-c ... hat103.jpg
with a few changes: No external bias jacks, HT wires on the opposite side, HT fuse between bridge and ground.
Here are some pics from the build
https://drive.google.com/file/d/1mhQqoG ... sp=sharing
https://drive.google.com/file/d/1a0t8QZ ... sp=sharing
https://drive.google.com/file/d/1jpJ5eQ ... sp=sharing
https://drive.google.com/file/d/157_fK9 ... sp=sharing
https://drive.google.com/file/d/17p0ozX ... sp=sharing
https://drive.google.com/file/d/1cRSzDA ... sp=sharing
https://drive.google.com/file/d/1qJF74Q ... sp=sharing
https://drive.google.com/file/d/1DmcOGR ... sp=sharing
https://drive.google.com/file/d/1MPQ5pK ... sp=sharing
The problem is that the sweep of the presence pot is not evenly distributed. seems like all changes are happening on the last quarter of the pot. no noticeable difference in the first 3/4 of the pot.
I have looked at a couple other schematics and noticed 2 variations:
lower filter cap from 100n to 47n
https://hiwatt.org/Schematics/DR_Pre4Input_v1a.gif
increased wiper resistance to ground from 100R to 470R
https://hiwatt.org/Schematics/DR_Pre4Input405.gif
My question is if any of these changes will make the sweep more usable and distributed across the pot without affecting the way the NFB works. and if not what else can be done.