Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on May 31, 2011, 05:22:23 pm

Title: Tube change in MB Triple Rectifier need a clarification
Post by: kagliostro on May 31, 2011, 05:22:23 pm

My son led me a Mesa Boogie Triple Rectifier that is of a friend

he asked me to change the tubes with new ones and to set bias

If I'm not wrong Mesa didn't allow the tuning of the bias, the bias voltage is set by a resistor and there is no need for setting it (or the Triple Rectifier is different ??)

my question is about the tubes

now the amp has on it 6 x 6L6 tubes and I received from my son 3 pairs of matched tubes, not a sextet of matched tubes

I think I must put 1 tube of one pair in one side of the PP branch and the other tube on the other branch

the same for the other 2 pairs of tubes

someone knows which are the pairs of the final tubes in the Triple Rectifier ?

example: (A) (B) (C) (C) (B) (A)  or something like (A) (A) (B) (B) (C) (C) ??????

Must I look to the circuit for establish the right pairs ?

I've many MB schematics, I've also the dual rectifier schematic but don't have the Triple Rectifier schematic, have you a link for that ?

Thanks

Kagliostro

Title: Re: Tube change in MB Triple Rectifier need a clarification
Post by: sluckey on June 01, 2011, 06:57:51 am

Take one tube from each pair and plug in so they will be connected to one side of the OT. Put the remaining tubes in the other sockets.

Title: Re: Tube change in MB Triple Rectifier need a clarification
Post by: VMS on June 01, 2011, 08:36:45 am

I think it's like this:

Quote from: kagliostro on May 31, 2011, 05:22:23 pm

example: (A) (B) (C) (C) (B) (A) 

Try googling: pulling tubes in triple rectifier

Title: Re: Tube change in MB Triple Rectifier need a clarification
Post by: OldHouseScott on June 01, 2011, 08:55:07 am

Yes, the fixed bias is non-adjustable. It is set by resistors. I believe there is a switch to allow 6L6s or EL34s. You are supposed to use Boogie tubes that are graded for a particular bias according to their matching and grading system, but Eurotubes and other distributors have tube sets that are graded for use in Boogies.

Title: Re: Tube change in MB Triple Rectifier need a clarification
Post by: Jack1962 on June 01, 2011, 09:18:52 am

tubes are inserted as Sluckey stated , Mesa claims there is no need to rebias , however I usually do for the best preformance of the tubes.

                                                    Rock On

Title: Re: Tube change in MB Triple Rectifier need a clarification
Post by: kagliostro on June 01, 2011, 01:07:50 pm

Thanks to all

I'll do as Sluckey told

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(A) (B) (C) (C) (B) (A)

also I think is something like this but I must control

---

Thanks again

Kagliostro