It is currently Mon Mar 16, 2020 1:42 pm

All times are UTC - 7 hours



Post new topic Reply to topic  [ 4 posts ] 
Author Message
Post subject: 65 SRRI Biasing
Posted: Thu Dec 07, 2017 6:52 am
Offline
Hobbyist
Hobbyist

Joined: Thu Dec 07, 2017 6:35 am
Posts: 2
Hi Folks!
I just purchased a brand new 65 SRRI for a back up of my 2003 65 SRRI. I decided to re-tube my 2003 so both amps would be close to same performance and, I used (as always) the GT line of factory tubes.
Well, my brand new Super Reverb (out of the box) measured in at a very happy 33 and 34.5ma which made me very satisfied as that's where I've been setting my bias for decades on these amps.
The problem is that my 2003 measured in at 29ma and 32.2ma and, that was maxxed out on the bias pot.
The amp sounds fine with NO obvious problems.
Has anyone experienced this before or can you ad your opinion on what may be causing this? Thank you for your time!


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: 65 SRRI Biasing
Posted: Fri Dec 08, 2017 10:51 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
65 Reissue wrote:
Hi Folks!

Well, my brand new Super Reverb (out of the box) measured in at a very happy 33 and 34.5ma which made me very satisfied as that's where I've been setting my bias for decades on these amps.
The problem is that my 2003 measured in at 29ma and 32.2ma and, that was maxxed out on the bias pot.

Has anyone experienced this before or can you ad your opinion on what may be causing this? Thank you for your time!


Bias milliamps mean nothing without knowing Tube's plate voltage.
Are plate voltages are same on both amps ?

And did amps's Outputs tubes are exactly with the same specs ?
2003 SRRI could have weak output tubes.


Last edited by stratele52 on Fri Dec 08, 2017 1:52 pm, edited 1 time in total.

Top
Profile
Post subject: Re: 65 SRRI Biasing
Posted: Fri Dec 08, 2017 11:40 am
Offline
Hobbyist
Hobbyist

Joined: Thu Dec 07, 2017 6:35 am
Posts: 2
stratele52 wrote:
65 Reissue wrote:
Hi Folks!

Well, my brand new Super Reverb (out of the box) measured in at a very happy 33 and 34.5ma which made me very satisfied as that's where I've been setting my bias for decades on these amps.
The problem is that my 2003 measured in at 29ma and 32.2ma and, that was maxxed out on the bias pot.

I will check plate voltages for tomorrow. Output tubes for the 2003 65 srri in question are brand new GT6L6-R.
New GT 5AR4 rectifier and all 4 new Mullard CV4004 12ax7 preamp tubes with 2 -12at7 GT PI and reverb tubes.
Has anyone experienced this before or can you ad your opinion on what may be causing this? Thank you for your time!


Bias milliamps mean nothing without knowing Tube's plate voltage.
Are plate voltages are same on both amps ?

And if amps Outputs tubes are exactly with the same specs.
2003 SRRI may have weak output tubes.


Top
Profile
Post subject: Re: 65 SRRI Biasing
Posted: Fri Dec 08, 2017 1:52 pm
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
And did amps's Outputs tubes are exactly with the same specs ?
2003 SRRI could have weak output tubes.


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 4 posts ] 

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: