Twin Reverb Tubes

Boo Bernstein · From: Los Angeles, CA

As of late, I have been playing around with a 65 Twin Custom 15. On my 1975 Silverface Twin, the tubes get very hot. On the new Twin, they do not. Just curious -- is this because of the design of newer tubes or the design of the amp or does it mean the tubes need to be biased or anything else? Thanks in advance. Boo

Drew Howard · From: 48854

How old are the tubes? I have a '75 SFTR as well.

Boo Bernstein · From: Los Angeles, CA

The Custom 15 tubes are new. I can't honestly say how old the Silverface tubes are because I recently got the amp back from my brother who lives on the other Coast. There's a chance that a few of the tubes may go back to the 70's (although the amp has been serviced a number of times over the years) while others have been replaced along the way.

That said, it seems to me that with any of my tube amps, the power tubes tend to get hot. With the new amp that isn't happening and it seems strange to me.

Thanks again, Boo

John Billings · From: Ohio, USA

I think Fender probably biases the tubes pretty cold, so they make it through the warranty period. I'd get them biased right, which, to your ear, may turn out to be biased right where they are now!

Donny Hinson · From: Glen Burnie, Md. U.S.A.

Bias will have a big effect on how hot the tubes run, as will the actual physical design of the tubes, and the socket configuration. Also, the later S/F amps (100w & 135w) have higher voltages on the plates of the 6L6's, so that might have an effect, too.

Interestingly enough, hot tubes usually perform better than cooler tubes, which is directly opposite of power transistors, whose output goes down with increased temperature.

Boo Bernstein · From: Los Angeles, CA

Thanks for your input. I don't know about the specifics of the electronics, but, psychologically, tubes running hot just feels like there's more harmonics going on Smile

I also have felt that over the years as the tubes in my amps "burned in," they seemed to sound better. Thanks again, Boo

Tim Whitlock · From: Colorado, USA

John's right. The Re-Issue Twins are biased very cold at the factory. If you bias it hotter I think you'll find it warms up the sound considerably.

James Morehead · From: Prague, Oklahoma, USA - R.I.P.

On the other hand, for clear clean steel tone, if you have a set of OLDER tubes that you really like, you can bias them a little bit colder, so you don't burn them out so quickly. Cool them down a little, you will hardly hear the difference running cooler, for that clear clean headroom.
Now if you want some six string crunch, disregard this. Push those tubes harder.

Jim Sliff · From: Lawndale California, USA

James Morehead · From: Prague, Oklahoma, USA - R.I.P.

Very well said, Jim S. Cool

John Billings · From: Ohio, USA

Jim, you'll notice that that quote was not actually from me. And that I did add, "I'd get them biased right, which, to your ear, may turn out to be biased right where they are now!"
We are in complete agreement according to :"They almost ALL come from the factory biased very cold for tube life...every new tube amp should go to a tech for "dialing in" to your particular playing style and tonal preference."

Jim Sliff · From: Lawndale California, USA

John, I wasn't quoting you. The "snip" was from Tim's post.

I've done the same thing and was just being cautionary. We often forget most players have no idea what "hot" or "cold" bias means...or even what bias settings do to the sound of an amp. Often the most "guilty (grin) are "boomers" who came back to playing after decades off - they used to be able to buy tubes at the corner drugstore that would work fine. QC was completely different in the 60's and you have to be much more careful and make adjustments (and sometimes other parts changes) with every power tube change.
_________________
No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional

John Billings · From: Ohio, USA

I know Jim! It's just that my name was at the beginning of the quote. I just wanted others to know that I didn't Eggs Ackley say that.

Boo Bernstein · From: Los Angeles, CA

Thanks again to everyone for their input.

Jim, you mention that it really pays to learn to bias an amp -- that would be great. What would be your suggestion to learn this process ... I'd like to avoid electrocuting myself if at all possible. Smile

Thanks again, Boo

Mike Poholsky · From: Kansas, USA

Hey Jim, Any good recommendations for material to learn about this stuff for ones self. I can see the advantage but have not really been electronically inclined, but am interested in learning now. Thanks to all the great info on this Forum. Particularly for older Fenders. Sorry, didn't read the previous post.
_________________
Zumsteel 12 Universal
SGBB
ShoBud VP
'64 Fender Twin Reverb/Fox Rehab
Fender Steel King w/BW 1501-4
FX to Taste

Alan Tanner · From: Near Dayton, Ohio

Alan Tanner · From: Near Dayton, Ohio

Jim Sliff · From: Lawndale California, USA

The referenced site is OK, but tuned towards Fender's modern Ho Rod and other higher-gain, printed circuit board amps. Here's another that's more generic (and please note ALL these sites have a few technical errors and/or disagreement!):

http://www.geofex.com/tubeampfaq/tafaqndx.htm

another:
http://www.kcanostubes.com/content/

One of the best is a discussion forum on the Webwervst speaker page at:

[url] www.tedweber.com.[/url]

Ted also sells a tool called a Bias Rite (several versions) that allows you to bias your amp without taking it apart, which is MUCH safer. You still often have to have an amp modified for adjustable bias, but there's no cheaper and more valuable mod you can do!

To continue the safety note - NEVER open an amp chassis unless you know how to discharge filter caps.

If that last sentence made no sense, forget it - take your amp to a tech. Really, to work on an amp you should have at least had high-school electronics. Without SOME basics you're in danger of 1) killing your amp, and 2) killing yourself.

There are several books that are helpful. Most of them either have some technical errors or are catalogs disguised as $40 books (The Groove Tubes Book is nice to have, but as a tech reference it's a total waste). Although it gets dissed a lot, Gerald Weber's "Hip Guide to Vintage Tube Amps" is probably the best basic introduction to tube guitar amplification, assuming you have at least a tiny bit of knowledge (i.e. know what a resistor and capacitor do, know what a transformer looks like, and know how to solder.). The O'Conner books are better technical references but assuming a working knowledge of electronics.

Things you need to start -

Resistor and capacitor code/color charts (printed of the 'net).

Soldering irons (40 watt) for normal wiring and a big one - 80 watts or a mini-torch - for chassis ground wires. Note - DO NOT start learning on printed circuit boards...just take those to a tech. They are almost impossible for amateurs to solder correctly.

Solder - ROSIN core...never acid acid core.

A cheap "solder sucker" - rubber bulb for removing solder by vacuum action.

Small, weighted units with two arms and alligator clips. You can't do without one - trust me.

Wire - 16-18 gage in different colors. Solid or stranded are both generally OK.

Chopsticks - yes, chopsticks. Best non-conductive tool for poking around looking for loose parts.

General stuff like screwdrivers,nut drivers, wire strippers, wire cutters, several pair of various needle-nose pliers.

A decent digital multimeter. NOT a cheapo needle one, and you don't need a $200 Fluke. $30-40 gets you a decent one for amp work, but if you're serious get the Fluke.

Wire heat-shrink tubing in various colors/sizes. Works better and looks MUCH better than tape!

Contact cleaner/lubricant. NOT just cleaner - that'll ruin pots.

For most Fender amps, two sets of 10-12" 2x4's stacked 3-4 high, with small nails for the chassis mounting holes. This is how you work on a chassis upside-down with the tubes still in the amp!

Copies of a few simple schematics AND layouts - schematics are electronic technical drawings of a circuit; "layout" is the physical position of parts on a chassis. Start by looking at various Champs, and work up from there. You can see/download here:

http://www.ampwares.com/ffg/

More quirky, but debunks many long-held opinions:

http://tone-lizard.com/

I'm sure I've forgotten a few basics, but you'll get the idea.

Also, it's good to frequent the Telecaster and Fender forum amp pages,especially th Fender pre-1985 section. There are professional techs that hang there and on the Weber board.

There are also many more amp-specific boards, but they are very technical and a newbie will be chewed up and spit out in seconds.

A couple more notes:

The Weber book is especially good for instructions to convert a newer (silverface) Fender amp to an adjustable bias. That and the Weber site AND Bias Rite are invaluable. Once you can bias power tubes and learn what the "safe zone" is, you can bias in minutes (instead of hours), not expose yourself to lethal voltage/current, and quickly adjust your amp for various venues. Many players still think there are stock "settings" you can use for amp tone controls in any venue, adjusting only the volume, which is ridiculous - REALLY tone-conscious players not only fine-tune their tone controls, but will rebias when playing a small club or a huge outdoor gig - it makes a tremendous difference in headroom and amp warmth. I do almost every time.

SAFETY - I can't repeat this enough. Capacitors in amps store electricity. This stored juice is strong enough to KILL you if you touch the wrong part inside an amp EVEN IF IT IS UNPLUGGED AND HAS BEEN SITTING FOR MONTHS!

NEVER work on anything until the filter caps have been discharged. Look that up and learn how to do it FIRST - otherwise you'll get excited, poke at something and get knocked across the room. Experienced techs STILL get nailed now and then.

OTOH, don't be afraid, just be safe. With a little knowledge you can do your own amp servicing (leave major work or disasters to a tech) and dial in your best tone yourself. It's fun...sometimes (g)...and definitely saves money.

I know guys who had 1 HS electronics class 30 years ago, bought a weber tweed Deluxe kit on a whim, and built in over a couple of weekends. MOST of it is not that hard, and you do NOT need an oscilloscope unless you're a pro tech solving major problems.

There's also quite a demand for good techs - the pro ones are usually backed up at least a month - and if you learn some basics you can be you whole band's tech and possibly make a little pocket-liner money doing work for others.

Just stay away from printed circuit boards (except for biasing) and solid-state.
_________________
No chops, but great tone
1930's/40's Rickenbacher/Rickenbacker 6&8 string lap steels
1921 Weissenborn Style 2; Hilo&Schireson hollownecks
Appalachian, Regal & Dobro squarenecks
1959 Fender 400 9+2 B6;1960's Fender 800 3+3+2; 1948 Fender Dual-8 Professional

Alan Tanner · From: Near Dayton, Ohio

Jon Light · From: Saugerties, NY

Because a picture is worth a bunch of words and because a video is worth a few pictures I got good value from the Gerald Weber amp tech video. It doesn't seem like it gives you a whole lot but the one thing it does give, for those of you (us) who have not done stuff inside an amp and want to be REALLY REALLY sure of what to connect where when discharging your capacitors, is a visual of how to do it. And how to do a cap job, among other things.
I am nothing more than a novice but when I acquired a few bf & sf amps a few years ago I knew I had to do this stuff myself, for $$ reasons as much as personal satisfaction reasons and even with the large amount of web resources available, it wasn't until I watched the procedure in the video that I was able to say "okay--I totally know what to do now."

THIS

is the video. And no, I don't mean to be shilling for it---it just happened to be exactly what I needed. If I had my way it would have much more useful content but I got my money's worth out of it for the safety specifics.

David L. Donald · From: Koh Samui Island, Thailand

If you know nothing about tuber amp inards,
go see a good local tech with both amps
and have them tested for bias voltage.

That hands on tech can likely tell you
what you have and if it's adjusted right or not.
And teach you how to safely deal with your amp.

Another issue is voltage from the wall
and the choice of power transformer in each amp.
One amp might have a older 110v input tap,
but be running on 125v from your wall.
So the 6.3 volt heater taps will actually be
running hotter than originialy intended.
While the other amp could have a 125v transformer
and the heaters run just right.
and not just the heaters but the whole B+ voltage
all along the amps sections could be much hotter
than originally designed 40 years ago.

Add to this the difference in operating temps.
for various tubes, and it's easy to find two Twins
running quite differently.
_________________
DLD, Chili farmer. Plus bananas and papaya too.

Real happiness has no strings attached.
But pedal steels have many!

Clyde Mattocks · From: Kinston, North Carolina, USA

Thanks Jim and David for some good info. I have a
reissue twin that is O.K., but that is about it.
A little too brittle.

I have a 70's Vibrolux that has always been sweet,
but a few months ago one of the old RCA 6L6's went
out on a gig. I stuck in a spare RCA, still sweet.
So, I figured I needed to put in a matched set, so I
get a set of Tung Sol's that the Fender tech
recommended. Viola, my Vibrolux sounded just like my
brittle twin. So now, I'm asking is this all my twin
needs to sweeten it is the right power tubes?
_________________
LeGrande II, Nash. 112, Fender Twin Tone Master, Session 400, Harlow Dobro, R.Q.Jones Dobro

David L. Donald · From: Koh Samui Island, Thailand

Clyde every single thing in the signal chain effects the tone.
So yes different tubes CAN give a different sound.

If the new amp is a bit brittle you can try some
upscale oil filled caps like Sozo or Mojo etc.
Thes can mellow out the amp after they break in.
If you have 2-3 Orange drops between stages,
try a warmer cap and ti likely will get closer
to your tastes. Ask the tech about this, he'll know.

Some tubes are bright and harsh, Electro harmonics have this rep,
While some tubes have a fat warm sound.

Some brighten up an dark amp and make a crisp amp annorying.
While the other can make a dark amp sound like mud,
and a too bright amp sound smooth and creamy.

Here are some descriptions of tubes.
All subjective of course.

http://www.geocities.com/axeman31/tubes.html

http://www.watfordvalves.com/reports.asp

http://www.worldtubecompany.com/mm5/merchant.mvc?Screen=TF-2

And an enducational site with a slightly biased comic edge to it.

http://tone-lizard.com/Table_Of_Contents.htm
_________________
DLD, Chili farmer. Plus bananas and papaya too.

Real happiness has no strings attached.
But pedal steels have many!

Mike Poholsky · From: Kansas, USA

WOW! Thanks guys. This forum is way cool. I'm having my '64 Twin Reverb redone right now by a buddy whose an amp tech, and has agreed to let me be an assistant so I can learn. All this info will help shorten the learning curve. OK, Dumba** question: When you say "biasing your amp" what exactly does that mean and how does it affect your tone?
_________________
Zumsteel 12 Universal
SGBB
ShoBud VP
'64 Fender Twin Reverb/Fox Rehab
Fender Steel King w/BW 1501-4
FX to Taste

Jon Light · From: Saugerties, NY

Mike---I really don't want to try to paraphrase this because I will probably end up revealing the depth of my own lack of comprehension so I'll just post this link---there are likely better sources too. Try googling a question like:

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