It is currently Tue Mar 17, 2020 12:58 am

All times are UTC - 7 hours



Post new topic Reply to topic  [ 3 posts ] 
Author Message
Post subject: Biasing Fender The Twin "Evil Twin" red knob 1989-
Posted: Thu Oct 15, 2009 8:03 am
Offline
Hobbyist
Hobbyist

Joined: Thu Oct 15, 2009 7:51 am
Posts: 4
I bought this amp in 1991 used and some of the tubes are still original. I want to know how to bias it. I see that it says to bias it at 40 millivolts- .04 volts- but the manual for the new Twins says to do .08 for best sound, .06 for good sound and long life and .04 for longest life. Does this apply to my 1990 Twin as well? Would I get better sound jacking it up to .o8 or is this dangerous?

Also, I am interested in running this amp on only two tubes to save money and because the extra power is just a waste on me as I don't need it loud. I see that I have to change the speaker ohm output to 8 ohm from the current 16. Do I still bias it the same way at .04?

Anyone have any preferred power tubes they run on this thing? How about preamp tubes?

Finally, I recently started using this amp with a Sholz Powersoak so I can crank it up to higher gain without blowing my ear drums. The Powersoak only takes 8 or 4 ohm loads although it does have the option to output to a 4, 8 or 16 ohm speaker. I currently have the Fender The Twin outputting at 8 ohm then into the Powersoak where it goes out into the Fender speakers which are two 8 ohms in series for a total of 16 ohms. Is there any problem with me running 4 tubes and having the output set to 8 ohm? I assumed it was for use on different types of speaker cab requirements. Is the setting really dependent on how many tubes you are running? Should it only be set to 8 ohm if I'm running two tubes?

Lots of questions, I know. I've looked all over the net and can't find specific answers.


Top
Profile
Fender Play Winter Sale 2020
Post subject:
Posted: Thu Oct 15, 2009 2:53 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Tue Aug 07, 2007 2:19 pm
Posts: 8827
The new Twins are 85 watts. The Evil Twins are a bit different.


Top
Profile
Post subject: Red Knob Twin
Posted: Thu Oct 15, 2009 6:10 pm
Offline
Hobbyist
Hobbyist

Joined: Thu Oct 15, 2009 7:51 am
Posts: 4
Well, I figured they're different. I will stick to the .04 volt recommendation until someone tells me differently. I read on an old chatroom thread that I should reduce the voltage to .02 if I'm only running two tubes. I would like confirmation if anyone knows.

Anyway, this guy at Eurotubes is showing how to make amps have more power tube distortion, you can boost the voltage a bit higher than the recommended settings, but I don't know what those settings would be for an Evil Twin. I don't want to guess and break the thing.

I'd also like to do this myself instead of taking it to an amp tech any paying $300 for tubes and service. I mean, I will if I have to. I have a lot of amps and I got them all used or demos and cheap and I don't want to spend as much on maintenance as I do on buying the amp if I can help it. I'd pay for something beyond what I'm capable of, but I think changing tubes and biasing an amp should be like changing oil on a car or strings on a guitar. The trouble is finding the info specific to my amp.


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 3 posts ] 

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 1 guest


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: