Champ-type amp with 6AU6?

Discussion:

(too old to reply)

w***@hotmail.com

2005-12-09 23:29:44 UTC

I just got a Silvertone 1431 on ebay with 6X5GT rectifier, 6AU6 pre-amp
and 6V6GT. It's my xmas present to myself but it hasn't arrived yet.
How will the 6AU6 make it sound different from an old Champ?

Doggone

2005-12-10 03:15:35 UTC

Permalink

Post by w***@hotmail.com
I just got a Silvertone 1431 on ebay with 6X5GT rectifier, 6AU6 pre-amp
and 6V6GT. It's my xmas present to myself but it hasn't arrived yet.
How will the 6AU6 make it sound different from an old Champ?

Nice old amp Waldo. $117.50 is a good price too. And the guy has resonable
shipping rates. Patience pays doesn't it. It looks like it'll need a cap job
amd new tubes. Are you up to it? You can do it, we can help. (Just like at
Home Depot)

The 6AU6 will make it sound different than a Champ. So will the different
speaker, the 6X5, the output transformer, the cabinet, the tone circuit...
It's not a Champ, there's no reason why it would sound like one. It should
sound just like a Silvertone 1431 should. I'm sure you'll like it.

Enjoy your amp.

--
If it ain't broke, fix it till it is.

Phil S

2005-12-10 03:20:31 UTC

Permalink

6AU6 is a pentode with much more gain according to the specs. How it sounds
probably depends on the circuit, though, as much as the tube. You can
always build it into a Champ if so inclined.

Doggone

2005-12-10 03:40:53 UTC

Permalink

Post by Phil S

6AU6 is a pentode with much more gain according to the specs. How it
sounds probably depends on the circuit, though, as much as the tube.
You can always build it into a Champ if so inclined.

Phil, the 5C1 Champ has a 6SJ7 pentode and a 6V6 output tube. But that's
where the similarities end.

Question
Has the Fender Champ become some sort of a benchmark to which all other small
amps are compared? I have a Champ and although it's a fine little amp, its no
holy grail. The Champ is nothing more than the VW Bug of guitar amps. No one
would convert a Corvair to a Bug? Why hack a fine old Silvertone into a
Champ?

--
If it ain't broke, fix it till it is.

Phil S

2005-12-10 14:22:22 UTC

Permalink

Post by Doggone

Post by Phil S

6AU6 is a pentode with much more gain according to the specs. How it
sounds probably depends on the circuit, though, as much as the tube.
You can always build it into a Champ if so inclined.

Phil, the 5C1 Champ has a 6SJ7 pentode and a 6V6 output tube. But that's
where the similarities end.
Question
Has the Fender Champ become some sort of a benchmark to which all other small
amps are compared? I have a Champ and although it's a fine little amp, its no
holy grail. The Champ is nothing more than the VW Bug of guitar amps. No one
would convert a Corvair to a Bug? Why hack a fine old Silvertone into a
Champ?
--
If it ain't broke, fix it till it is.

Agreed. I was just reacting to the OP. Sounds like maybe he wants a Champ?
I dunno.

w***@hotmail.com

2005-12-10 18:26:23 UTC

Permalink

Post by Phil S

Post by Doggone
Why hack a fine old Silvertone into a
Champ?

Agreed. I was just reacting to the OP. Sounds like maybe he wants a Champ?

Oh no, I have no plans to radically rebuild it. I bought the Silvertone
to have something to learn on. Restoring this amp will be my first
electronics project in decades, other than your basic homeowner house
wiring chores. From the few web reviews I've found, it sounds like this
amp might have a cleaner and darker sound than the Champ, which is fine
with me as I play a lot of jazz. I got it for $117, which is a fair
market price but not really a bargain. A few hours after my auction
ended, someone else won a 3-tube 6v6 Silvertone for $48. Now that was
more of a score. I wish I had held out for that auction.

I did get a real pretty Davis PA amp with two 6L6s in the power stage
and a very attractive wood enclosure, for $23. Rebuilding that might be
my second project after the Silvertone, if I feel up to it.

I know how to solder, use a VOM, and read a schematic, and that's about
it. When I was a kid back in the 70s I had one year of electronics in
9th grade. I built a couple of little Radio Shack kits and I got a
novice ham radio license. Then once I got my first girlfriend I
basically dropped all of my geek hobbies. Now I'm regressing back to
childhood in my interests.

Phil S

2005-12-10 22:22:59 UTC

Permalink

Post by w***@hotmail.com

Post by Phil S

Post by Doggone
Why hack a fine old Silvertone into a
Champ?

Agreed. I was just reacting to the OP. Sounds like maybe he wants a Champ?

Oh no, I have no plans to radically rebuild it. I bought the Silvertone
to have something to learn on. Restoring this amp will be my first
electronics project in decades, other than your basic homeowner house
wiring chores. From the few web reviews I've found, it sounds like this
amp might have a cleaner and darker sound than the Champ, which is fine
with me as I play a lot of jazz. I got it for $117, which is a fair
market price but not really a bargain. A few hours after my auction
ended, someone else won a 3-tube 6v6 Silvertone for $48. Now that was
more of a score. I wish I had held out for that auction.
I did get a real pretty Davis PA amp with two 6L6s in the power stage
and a very attractive wood enclosure, for $23. Rebuilding that might be
my second project after the Silvertone, if I feel up to it.
I know how to solder, use a VOM, and read a schematic, and that's about
it. When I was a kid back in the 70s I had one year of electronics in
9th grade. I built a couple of little Radio Shack kits and I got a
novice ham radio license. Then once I got my first girlfriend I
basically dropped all of my geek hobbies. Now I'm regressing back to
childhood in my interests.

You'll be able to do this. Get your safety refresher at the AGA website:
www.aga.rru.com
Enjoy the project. Let us know how it turns out.
BTW, don't look back at that other auction. This kind of thing happens all
the time. You still got a great deal.

w***@hotmail.com

2005-12-19 23:01:25 UTC

Permalink

It arrived and is better condition than advertised. It still has the
original Silvertone tubes. My major complaint is that while it makes a
nice clean tone, it doesn't really distort much at all. Turned all the
way up you get just the hint of breakup. This is with a Squier tele,
stock pickups that I would guess are pretty low output. I have a Duncan
59 that I'm planning to put in the neck position.

One of the reasons I wanted a small tube amp was to enjoy tube
distortion at a low volume. I don't need metal noise, just a nice
overdriven blues tone. Will recapping or retubing change this situation
much? I'm also considering removing the one-knob tone stack in the
hopes of driving the power tube a little harder. Suggestions or
opinions?

tnx, waldo

oasysco

2005-12-19 23:12:17 UTC

Permalink

It still has the original Silvertone tubes.

Every silvertoen amp I have ever had (about 5 or 6 of 'em) has had at
least most of the original tubes! And they all worked well.

greg

2005-12-21 02:25:45 UTC

Permalink

Post by w***@hotmail.com
overdriven blues tone. Will recapping or retubing change this situation
much? I'm also considering removing the one-knob tone stack in the
hopes of driving the power tube a little harder. Suggestions or
opinions?

Recapping will probably bring voltages up slightly. This will make the
amp a bit louder, but.... For more crunch, you want less headroom, that
is lower plate voltage on the power tube and higher gain on the
preamp. New tubes are not likely to help much.
Unless you plan to make drastic design changes, a better option might
be to do the recap, install an isolation transformer, then buy a pedal
to boost the guitar signal.

Porky

w***@hotmail.com

2005-12-21 02:39:41 UTC

Permalink

Post by JK

Thanks, very helpful info.

Post by JK
Unless you plan to make drastic design changes, a better option might
be to do the recap, install an isolation transformer, then buy a pedal
to boost the guitar signal.

It has a power trafo. This is not a radio tube circuit. I have
considered a boost pedal and will probably try that approach. Is it
correct that the pedal will mainly overdrive the preamp tube? What if I
want to hear the power tube overdriven instead...will the boost pedal
make that happen at all?

I was hoping that lifting the tone control might give me more gain from
the preamp tube. What are some other techniques of increasing the gain
in a simple three-tube amp? In a circuit this simple, changing it
doesn't seem all that drastic to me. I'm not contemplating anything
that wouldn't be easy to reverse if I didn't like it.

tnx again, waldo

2005-12-21 04:18:55 UTC

Permalink

Post by w***@hotmail.com
It has a power trafo.

Yeah, sorry, I realized that after, from the tubes, obviously there's a
high V secondary and a 6 volt heater winding. Without seeing the
schemo, we are assuming the 6AU6 is biased in the usual way, pin 7 is
grounded and there is a high value resistor from the grid to ground.
This type of biasing some call it contact bias, is hard to alter in any
significant way. Search for ways to rewire the pentode preamp tube to
cathode biasing?

The power supply could be altered by adding another pi filter in front
of the supply to the OT and the power tube plate. Lowering the plate
voltage would change the tone a lot and give you the distortion you
want, butt.. this calls for experimenting. I would search for tips from
people who have done this already, so try the various amp forums.

If the volume control is on the input before the 6AU6, it injects noise
into the signal. I'd move it to between the preamp and the power stage.
The amp becomes instantly quieter when idling. Try bypassing the tone
pot with a jumper wire.

Maybe try alt.guitar.effects?