belensky
Member
Hey guys, wanted to share a cool discovery I made yesterday.
I’ve been dealing with this for a while: Diezel, like many EU amps, are stock-wired for 230 V wall voltage. EU mains is rated 230 V ±10%, which means anything between 207 and 253 V is legally acceptable., and at my place it’s always 235–240 V and never lower.
So my amps were always running a bit hotter, with more plate voltage. Bias had to be set hotter, tubes wore faster, transformers stressed more, and after a couple of hours of playing, the amp could basically double as a barbecue grill—and hum like a nuclear power plant.
Then I remembered something Dave Friedman said: he always sets European amps for 240 V. The idea is, if mains is a bit high (230+), 240 V is perfect; if it’s a bit low, it’s even better—smoother highs and gentler on tubes and transformers.
Then I came across the AC/DC rig rundown:
Same story: amps are set for 240 V, but they specifically keep wall voltage at 236 V (video at 9:30). Even picky players like Steve Stevens prefer slightly lower voltage.
So I checked the Diezel service manual and decided to go ahead and re-wire the transformer from 230 V to 240 V. Super simple—easier than swapping pickups in a guitar. The manual shows how (connect Pin 3→4 and Pin 7→8, pages 27–28
https://www.diezelamplification.com/manuals/service/service-manual_V1-1.pdf
After swapping, I double-checked and re-adjusted the bias—it shifted by 2–3 mA in my case. The best part: now, with nearly always 240 V at the wall, no recalculating needed. Before, I had to know the exact mains voltage and adjust bias accordingly; e.g., instead of 65 mA per tube pair, I’d have to set 67–68 mA.
Sound-wise… maybe placebo, as I haven’t done a proper A/B, but it really sounds better. Fans of lower voltage say it softens/darkens the sound and adds sag—which I didn’t necessarily want and worried about. But for me, it didn’t just get darker or saggy; it cleaned up some upper-end harshness and removed a weird edge in the tone. Before, the amp felt like it was struggling and trying too hard (if that makes sense). Subtle difference, but noticeable.
If anyone’s willing to tinker, check your mains first—my “230 V” is never really 230 V—and it might be easier to do the 240 V swap than stress your amp.
P.S. Scored a second load box, so now I can play all night in DAW with proper stereo and all the effects. Interesting observation: even with two identical amps, perfectly in-phase, there’s a cool pseudo double-tracking effect (not chorus, not phase spread, just the amps reacting slightly differently; tubes and circuits have small variances). Gives a richer, stereo, deeper sound—like running two cabs instead of one.
I’ve been dealing with this for a while: Diezel, like many EU amps, are stock-wired for 230 V wall voltage. EU mains is rated 230 V ±10%, which means anything between 207 and 253 V is legally acceptable., and at my place it’s always 235–240 V and never lower.
So my amps were always running a bit hotter, with more plate voltage. Bias had to be set hotter, tubes wore faster, transformers stressed more, and after a couple of hours of playing, the amp could basically double as a barbecue grill—and hum like a nuclear power plant.
Then I remembered something Dave Friedman said: he always sets European amps for 240 V. The idea is, if mains is a bit high (230+), 240 V is perfect; if it’s a bit low, it’s even better—smoother highs and gentler on tubes and transformers.
Then I came across the AC/DC rig rundown:
Same story: amps are set for 240 V, but they specifically keep wall voltage at 236 V (video at 9:30). Even picky players like Steve Stevens prefer slightly lower voltage.
So I checked the Diezel service manual and decided to go ahead and re-wire the transformer from 230 V to 240 V. Super simple—easier than swapping pickups in a guitar. The manual shows how (connect Pin 3→4 and Pin 7→8, pages 27–28
https://www.diezelamplification.com/manuals/service/service-manual_V1-1.pdf
After swapping, I double-checked and re-adjusted the bias—it shifted by 2–3 mA in my case. The best part: now, with nearly always 240 V at the wall, no recalculating needed. Before, I had to know the exact mains voltage and adjust bias accordingly; e.g., instead of 65 mA per tube pair, I’d have to set 67–68 mA.
Sound-wise… maybe placebo, as I haven’t done a proper A/B, but it really sounds better. Fans of lower voltage say it softens/darkens the sound and adds sag—which I didn’t necessarily want and worried about. But for me, it didn’t just get darker or saggy; it cleaned up some upper-end harshness and removed a weird edge in the tone. Before, the amp felt like it was struggling and trying too hard (if that makes sense). Subtle difference, but noticeable.
If anyone’s willing to tinker, check your mains first—my “230 V” is never really 230 V—and it might be easier to do the 240 V swap than stress your amp.
P.S. Scored a second load box, so now I can play all night in DAW with proper stereo and all the effects. Interesting observation: even with two identical amps, perfectly in-phase, there’s a cool pseudo double-tracking effect (not chorus, not phase spread, just the amps reacting slightly differently; tubes and circuits have small variances). Gives a richer, stereo, deeper sound—like running two cabs instead of one.
