Speeddemon
Well-known member
As some of you may know, I got an Engl Savage 60 back in my collection since 2017 (posted a thread here at the time too) and lately I've been noticing a 50Hz hum becoming more apparent (mine's the 230V version), together with some rumbly ticking sounds every now and then.
Given that this amp is 20+ years old, the electrolytic caps would most likely be the culprit. There were only 2 bigger ones in the filtering stage, a 47uF/500V and a 100uF/500V. I measured them with an ESR reader and the 100uF one looked to be on its last legs, measuring maybe 54uF, with a resistance of 44 Ohm (whereas the goal is <2 Ohm).
Today I received the new parts; yesterday I recapped 5 smaller electrolytics, but now I put in the new JJ 47uF and 100uF caps.
After removing the old 100uF, I tried to measure it, but no dice. Good thing I didn't wait!
The PCB looked to have a sharpie-written date of 05/95 on it, so the amp was built almost 27 years ago!
Well, the new caps were a major improvement. Almost no more hum, aside from what any amp puts out very silently and no artifacts either.
Together with those caps, I also bought a matched pair of JJ KT77's, to try out instead of the currently installed JJ EL34's...
I played, while recording the EL34's, turned the amp off, waited 15 minutes (to let the EL34's cool off), swapped the tubes and played and recorded again.
Unfortunately my phone's mic was so overloading that the recordings hardly show any difference, but the things I did notice were:
-KT77 has a tad smoother top-end and more/bigger bottom end.
-EL34 seems to respond more spongey for classic rock/hard rock stuff, whereas the stiffness of the KT77's seemed to veer better for metal than (hard)rock.
So far, the jury's still out whether I like the KT77's better...need to do some more tests soon.
Anyone else compared EL34's and KT77's in mid-wattage high gain amps?
Given that this amp is 20+ years old, the electrolytic caps would most likely be the culprit. There were only 2 bigger ones in the filtering stage, a 47uF/500V and a 100uF/500V. I measured them with an ESR reader and the 100uF one looked to be on its last legs, measuring maybe 54uF, with a resistance of 44 Ohm (whereas the goal is <2 Ohm).
Today I received the new parts; yesterday I recapped 5 smaller electrolytics, but now I put in the new JJ 47uF and 100uF caps.
After removing the old 100uF, I tried to measure it, but no dice. Good thing I didn't wait!
The PCB looked to have a sharpie-written date of 05/95 on it, so the amp was built almost 27 years ago!
Well, the new caps were a major improvement. Almost no more hum, aside from what any amp puts out very silently and no artifacts either.
Together with those caps, I also bought a matched pair of JJ KT77's, to try out instead of the currently installed JJ EL34's...
I played, while recording the EL34's, turned the amp off, waited 15 minutes (to let the EL34's cool off), swapped the tubes and played and recorded again.
Unfortunately my phone's mic was so overloading that the recordings hardly show any difference, but the things I did notice were:
-KT77 has a tad smoother top-end and more/bigger bottom end.
-EL34 seems to respond more spongey for classic rock/hard rock stuff, whereas the stiffness of the KT77's seemed to veer better for metal than (hard)rock.
So far, the jury's still out whether I like the KT77's better...need to do some more tests soon.
Anyone else compared EL34's and KT77's in mid-wattage high gain amps?