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Post subject: Fender twin reverb 65 RI questions
Posted: Fri Aug 21, 2009 2:08 pm
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Hello,
I am new to this forum and was wondering if anyone in this forum could answer some questions for me?
Let me begin by saying that I picked up a used 65 RI for about as low as I've ever seen one on craiglist. Let's just say that it was about the same price as a stand alone 212 cab with speakers. Anyways, I think the reason I got it so cheap was because the person selling it didn't look like he knew what was involved in keeping tube amps running good. I believe he felt that it would cost too much to repair, but after I inspected it, everything looked good, everything worked good, but the volume just wasnt there. Based on the QA sticker I knew it was about 11 years old and figured it might just meed a new set of tubes and some rebiasing. Well, I was maybe half way right. As soon as I had a chance, I took it apart, cleaned all the contacts, potmeters, switches, and removed and reinstalled all the tubes. To my suprise, I noticed huge increase in volume level(there were more than a couple of loose tubes). Still not as much as I've heard these go, but none the less, loud. Well I'm sure now that I got the deal of a lifetime, but I would still love to replace all the tubes as they appear to be the original tubes.
My question, can anyone here tell me how to bias the amp once I install the new tubes? I will be installing Winged "C" 6l6's matching quad and all new 12ax7's and 12at7's.
Thanks in advance.


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Post subject: Re: Fender twin reverb 65 RI questions
Posted: Sun Aug 23, 2009 1:44 pm
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fender323 wrote:
Hello,
I am new to this forum and was wondering if anyone in this forum could answer some questions for me?
Let me begin by saying that I picked up a used 65 RI for about as low as I've ever seen one on craiglist. Let's just say that it was about the same price as a stand alone 212 cab with speakers. Anyways, I think the reason I got it so cheap was because the person selling it didn't look like he knew what was involved in keeping tube amps running good. I believe he felt that it would cost too much to repair, but after I inspected it, everything looked good, everything worked good, but the volume just wasnt there. Based on the QA sticker I knew it was about 11 years old and figured it might just meed a new set of tubes and some rebiasing. Well, I was maybe half way right. As soon as I had a chance, I took it apart, cleaned all the contacts, potmeters, switches, and removed and reinstalled all the tubes. To my suprise, I noticed huge increase in volume level(there were more than a couple of loose tubes). Still not as much as I've heard these go, but none the less, loud. Well I'm sure now that I got the deal of a lifetime, but I would still love to replace all the tubes as they appear to be the original tubes.
My question, can anyone here tell me how to bias the amp once I install the new tubes? I will be installing Winged "C" 6l6's matching quad and all new 12ax7's and 12at7's.
Thanks in advance.


Welcome to the forum! From what I've just read, it sounds like you got yourself a very good deal on the TRRI. This link might help you
as far as biasing :

http://www.diyguitaramp.com/bias.html

Good luck! :wink:

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Post subject:
Posted: Sun Aug 23, 2009 5:26 pm
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Thanks for the link. I believe that I remember seeing a 1ohm resistor already installed on the amp when I took it apart so I should be able to follow through.


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Posted: Tue Aug 25, 2009 1:40 pm
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Hi Fender323,

Congrats on getting the Twin Reverb. They are a great sounding amp.
I know because I've got one too. :lol:

I can tell you, for a reference point, that mine came from the factory biased at 28ma on the 6L6 power tubes.

I have tried different tubes in it, and at higher bias points - 30ma, 32ma and up to 35ma.
All I got was more heat - sometimes a lot more heat - for a very, very slight bit of added warmth in the sound.

Knowing that the heat would cook the tubes and shorten their life - I went back to the 28ma setting that Fender used. It has that great Twin Reverb sound.

I think (IMHO) that the recommendations you will find on the Internet to run the tubes hot comes from a couple of things. One is trying to make a fine amp sound like some other amp. Maybe an amp that breaks up at volume. (some want EVERYTHING to break up :roll: ) The other is - there are tube dealers posting on these forums. The quicker you burn your tubes up, the quicker they get to sell you more. :wink:

Mine sounds just fine adjusted like Fender made it. :wink:

One set of tubes I ordered from a tube store in Canada. They use a nonstandard way of matching their tubes, and the set came with one tube way off - and the others were not very close. He wouldn't ever admit it was wrong.

So, I ordered the set thats in it from another source, Antique Electronics Supply. It's at http://www.tubesandmore.com/, if you are interested. I have bought from them with very good results. In my experience - They are good people to deal with. And the tubes did match pretty close and the amp sounds good.

That 1st set sits on the shelf in plain sight for anyone that comes in to see, just to remind me not to buy from that store ever again. And several have asked about them and why they set there. I just tell them the truth - and they thank me for the info. :wink:

Just trying to help with a little bit of FYI. :wink:

I hope you enjoy your amp. :)


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Posted: Sat Aug 29, 2009 10:11 pm
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rholloman wrote:
Hi Fender323,

Congrats on getting the Twin Reverb. They are a great sounding amp.
I know because I've got one too. :lol:

I can tell you, for a reference point, that mine came from the factory biased at 28ma on the 6L6 power tubes.

I have tried different tubes in it, and at higher bias points - 30ma, 32ma and up to 35ma.
All I got was more heat - sometimes a lot more heat - for a very, very slight bit of added warmth in the sound.

Knowing that the heat would cook the tubes and shorten their life - I went back to the 28ma setting that Fender used. It has that great Twin Reverb sound.

I think (IMHO) that the recommendations you will find on the Internet to run the tubes hot comes from a couple of things. One is trying to make a fine amp sound like some other amp. Maybe an amp that breaks up at volume. (some want EVERYTHING to break up :roll: ) The other is - there are tube dealers posting on these forums. The quicker you burn your tubes up, the quicker they get to sell you more. :wink:

Mine sounds just fine adjusted like Fender made it. :wink:

One set of tubes I ordered from a tube store in Canada. They use a nonstandard way of matching their tubes, and the set came with one tube way off - and the others were not very close. He wouldn't ever admit it was wrong.

So, I ordered the set thats in it from another source, Antique Electronics Supply. It's at http://www.tubesandmore.com/, if you are interested. I have bought from them with very good results. In my experience - They are good people to deal with. And the tubes did match pretty close and the amp sounds good.

That 1st set sits on the shelf in plain sight for anyone that comes in to see, just to remind me not to buy from that store ever again. And several have asked about them and why they set there. I just tell them the truth - and they thank me for the info. :wink:

Just trying to help with a little bit of FYI. :wink:

I hope you enjoy your amp. :)


Very usefull information. I have noticed that most dealers mark the bias point on the tubes. Would it be advisable to purchase tubes with a bias point close to the 28ma, or does it not make that much of a difference?


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Posted: Sun Aug 30, 2009 6:21 am
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fender323 wrote:
.....................
Very usefull information. I have noticed that most dealers mark the bias point on the tubes. Would it be advisable to purchase tubes with a bias point close to the 28ma, or does it not make that much of a difference?


I just get a matched quad - then adjust the bias after installing them.
I have found it best to check them out myself - no matter what some tube reseller says.

I use a couple of adapter sockets between the tube and the tube socket that allow me to plug into a mutimeter. Set it to the milliamp setting to see the ma. Similar to these "Weber Bias Rite" adapters. Another brand is called "Bias King". I saw it at Antique Electronics Supply. Under "Tech Supplies" then "test equipment".

I prefer to use a "plastic" (non metallic) screwdriver to insert in the bias adjustment "pot" for adjusting. (less 'noise' to make me jump :lol: ) (I don't have a source for that - I made my own :) )

With the sockets you don't have to remove the chassis from the cabinet as you do with some other methods. Which means less chance of getting into something that will kill you.

Good Luck :D

Standard disclaimer for any "sue happy" folks that may be out there reading this;
YMMV - don't attempt any of this unless you are trained in this field. Proceed at your own risk. Voltage and current in a tube amp can kill you. You've been warned. :roll:


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