axeman81
New member
Hey guys,
I've been wanting to check the bias of my Herbert for a while, but haven't taken the time to do it before tonight.
I always thought it had Ruby power tubes but upon closer inspection they are labeled TAD EL34B-STR.
Were these the stock power tubes for some time? I am also very curious of any variation in preamp tubes used from the factory during the 2003-2006 period.
My amp is #791. Although I am very happy with it and will never sell, it does not yet sound quite as good as the one I tried in-store a few years before (ca.2003) buying this one used. The guy at the store said at the time that that particular amp was equipped with 2 pairs of EL34 and 1 pair of 6L6.
Anyway the bias reading showed left pin was 59mA, center pin was 76mA, and right pin was 64mA. I will adjust it tomorrow (damn screwdriver was too tall
), I'm excited to see if the sound changes noticeably. I'm thinking to try all pairs at 70mA.
I will probably retube it pretty soon, but I am a bit torn about going for 6550's, or SED -c- EL34 or maybe even the old EL34 + 6L6 combo. So I am sort of chasing my "dream Herbert" tone, hence the inquiry if the preamp tubes have changed much or if it's "all in the preamp"!
- Rune
I've been wanting to check the bias of my Herbert for a while, but haven't taken the time to do it before tonight.
I always thought it had Ruby power tubes but upon closer inspection they are labeled TAD EL34B-STR.
Were these the stock power tubes for some time? I am also very curious of any variation in preamp tubes used from the factory during the 2003-2006 period.
My amp is #791. Although I am very happy with it and will never sell, it does not yet sound quite as good as the one I tried in-store a few years before (ca.2003) buying this one used. The guy at the store said at the time that that particular amp was equipped with 2 pairs of EL34 and 1 pair of 6L6.
Anyway the bias reading showed left pin was 59mA, center pin was 76mA, and right pin was 64mA. I will adjust it tomorrow (damn screwdriver was too tall
), I'm excited to see if the sound changes noticeably. I'm thinking to try all pairs at 70mA.I will probably retube it pretty soon, but I am a bit torn about going for 6550's, or SED -c- EL34 or maybe even the old EL34 + 6L6 combo. So I am sort of chasing my "dream Herbert" tone, hence the inquiry if the preamp tubes have changed much or if it's "all in the preamp"!
- Rune
I will take a closer look tonight and see what preamp tubes are in there.