Okay,
Time to get serious again, will be heating up the soldering iron shortly, so off to the grindstone it is.
Jerry
Blackheart BH5H Mod
Moderators: pompeiisneaks, Colossal
Re: Blackheart BH5H Mod
Well the modifacitons are done now and it is a different beast now.
Still has a higher than I would prefer high frequency sound, but the level of bass has increased dramatically. Also the TMB controls seem much more responsive.
Prior to the mod when I dimed the amp with the power scaling off, playing on the low strings it got loud and had good low end. Now, doing the same, the entire house rattles even with the bass at 0 with the bass dimed, pictures could fall off the walls.
Now just need to pick the type of Trainwreck to build!
Still has a higher than I would prefer high frequency sound, but the level of bass has increased dramatically. Also the TMB controls seem much more responsive.
Prior to the mod when I dimed the amp with the power scaling off, playing on the low strings it got loud and had good low end. Now, doing the same, the entire house rattles even with the bass at 0 with the bass dimed, pictures could fall off the walls.
Now just need to pick the type of Trainwreck to build!
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Re: Blackheart BH5H Mod
Jerry,
What mods did you end up with. I see you changed up the tonestack. Are you using 820R on the cathode of V1a and V1b? What bypass caps did you end up with?
There are some places to bleed some treble.
What mods did you end up with. I see you changed up the tonestack. Are you using 820R on the cathode of V1a and V1b? What bypass caps did you end up with?
There are some places to bleed some treble.
Re: Blackheart BH5H Mod
Hello Colossal,
First, I swapped all of the resistors in the preamp section for the RCMF60's keeping the same values on all but R2 changed to a 68K, R3 and R7 to 820R's, R5 to 33K and since I had to mess with it anyway for the master volume swap I changed R10 to the same value but with an RCMF60. For the caps, I put a Silver Mica 500pF at C2, I kept the same values otherwise in the tone stack but changed to the Mallory 150's 0.022uF 630V C3 and C4 and the same in C6. C8 I put a Mallory 150 of the same value 0.1uF 600V, C1 I kept as is, 22uF 50V but put a Orange Drop 715P 0.1uF in parallel with C1. C5 I took out the 1uF and put a Solen .68uF 630V. At C7 I changed from a 22uF 50V to a 33uF 63V. I unfortunately didn't get the 0.47uF 600V ordered to put in parallel with C13, but I drilled the holes out for it so it is ready to go when I place my next order. For the master volume I used the 250k CTS Pot with the 2m2 resistor hooked to the outer 2 lugs. In following your Diagram for the master volume I had to cut the trace on the under side of the pcb between the pads on R9 and R10 and drill holes on each side of the cut. I attached the center lug #2 wire to the hole on the R10 side, Lug #1 to the hole on the R9 side and Lug #3 to the original pad of R9 ground side.
It had been suggested to me previously that I should use 2 strand sheilded cable from this point to the master volume pot and all I had was 24 AWG, and I thought it should be a larger gauge wire and couldn't find any 2 stand sheilded wire locally or on the web in the 18 to 20 AWG size, so I made my own using RG6 75ohm coax, for the outer housing and the wire braid and foil sheild. I ran 3 18 AWG wires thru this and made sure the wire braid was long enough to reach the star ground on the chassis at the rear. and tied it there with a lug end and tied it with a lug on a screw standoff at the front of the pcb near the mv pot.
When I first powered it on though I didn't have any sound in the preamp section and had to trouble shoot why. It turned out that the holes I drilled for the Master volume between R9 and R10, were making contact with the trace on the top of the board and grounding out pin 6 (plate 1) on the preamp tube. Took my wifes electric manicure tool with a round deburing bit and ground the copper from the top trace away from the holes I had drilled and solved the problem. As long as she doesn't know anyway.
I remember you spoke of C2 using a Silver Mica 250pF with a Ceramic 250pF for a grainer sound, I have the SM 250 but will have to come up with a ceramic to try that.
Anyway, suggestions or comments?
Thinking toward maybe an Express for the first build, but still undecided and open to suggestion.
Thanks Colossal,
Jerry
First, I swapped all of the resistors in the preamp section for the RCMF60's keeping the same values on all but R2 changed to a 68K, R3 and R7 to 820R's, R5 to 33K and since I had to mess with it anyway for the master volume swap I changed R10 to the same value but with an RCMF60. For the caps, I put a Silver Mica 500pF at C2, I kept the same values otherwise in the tone stack but changed to the Mallory 150's 0.022uF 630V C3 and C4 and the same in C6. C8 I put a Mallory 150 of the same value 0.1uF 600V, C1 I kept as is, 22uF 50V but put a Orange Drop 715P 0.1uF in parallel with C1. C5 I took out the 1uF and put a Solen .68uF 630V. At C7 I changed from a 22uF 50V to a 33uF 63V. I unfortunately didn't get the 0.47uF 600V ordered to put in parallel with C13, but I drilled the holes out for it so it is ready to go when I place my next order. For the master volume I used the 250k CTS Pot with the 2m2 resistor hooked to the outer 2 lugs. In following your Diagram for the master volume I had to cut the trace on the under side of the pcb between the pads on R9 and R10 and drill holes on each side of the cut. I attached the center lug #2 wire to the hole on the R10 side, Lug #1 to the hole on the R9 side and Lug #3 to the original pad of R9 ground side.
It had been suggested to me previously that I should use 2 strand sheilded cable from this point to the master volume pot and all I had was 24 AWG, and I thought it should be a larger gauge wire and couldn't find any 2 stand sheilded wire locally or on the web in the 18 to 20 AWG size, so I made my own using RG6 75ohm coax, for the outer housing and the wire braid and foil sheild. I ran 3 18 AWG wires thru this and made sure the wire braid was long enough to reach the star ground on the chassis at the rear. and tied it there with a lug end and tied it with a lug on a screw standoff at the front of the pcb near the mv pot.
When I first powered it on though I didn't have any sound in the preamp section and had to trouble shoot why. It turned out that the holes I drilled for the Master volume between R9 and R10, were making contact with the trace on the top of the board and grounding out pin 6 (plate 1) on the preamp tube. Took my wifes electric manicure tool with a round deburing bit and ground the copper from the top trace away from the holes I had drilled and solved the problem. As long as she doesn't know anyway.
I remember you spoke of C2 using a Silver Mica 250pF with a Ceramic 250pF for a grainer sound, I have the SM 250 but will have to come up with a ceramic to try that.
Anyway, suggestions or comments?
Thinking toward maybe an Express for the first build, but still undecided and open to suggestion.
Thanks Colossal,
Jerry
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