Biasing a 2010 herbert

  • Thread starter Thread starter gargamelesp
  • Start date Start date
G

gargamelesp

New member
hi guys, i got a herbert made this year and it dosent have the external test points anymore so im wondering if any of you guys have any experience on how to bias the amp since the tech section of the diezel website only shows the information for those with the external points

i plan to put 4 6550s inside the amp and keep 2 EL34's but which position should i keep the EL 34s?

thanks!
 
A description for biasing is inside on the board.

We had bad expreience with the 6550 btw.
 
gargamelesp":22xyh5wp said:
hi guys, i got a herbert made this year and it dosent have the external test points anymore so im wondering if any of you guys have any experience on how to bias the amp since the tech section of the diezel website only shows the information for those with the external points

i plan to put 4 6550s inside the amp and keep 2 EL34's but which position should i keep the EL 34s?

thanks!
Click to expand...

Use this link, it tells you how to do one with no external bias points: http://diezel.typo3.inpublica.de/tech-corner.3.0.html

The power tubes are in pairs the following way: Looking at the back of the amp at the power tubes, they are 1-6 left to right. 1 and 6 are a pair, 2 and 5 are a pair, and 3 and 4 are a pair. I would leave the 34s 1 and 6 and use the 6550s everywhere else. :thumbsup:
 
Peter Diezel":2edkyo5s said:
A description for biasing is inside on the board.

We had bad expreience with the 6550 btw.
Click to expand...

What happened? Just a bad supply of 6550s or do the later Herberts not work well with them?

I was planning on putting in 6550s in my 2004 Herbert. I have heard from a bunch of folks that they sound awesome with 6550s in them... :confused:
 
The later batches of SED 6550's started to go bad. Like many things they have good production runs
and bad ones. They still need to sell the tubes and the amp manufacturers and then us are the guinea pigs.
All tube makers are like this. As long as they think the tube will last to the end of the warranty they don't care
if one bad batch goes out. They don't have the military or medical necessity to make them in these tolerances.
 
i have only gotten one bad 6550 out of about 10 matched pairs i have bought...including a barely used pair. And none have ever failed in my Diezels & i run em hot. But i do know how the tube market is...sometimes good ...sometimes bad.

i put the 2 EL34s in the middle 2 of my Herbie. Sounds killer...give it a whirl.
 
You must log in or register to reply here.
Back
Top