Silvertone 1481 mods

[galaxiex]

So I acquired this 1481 some time ago...

A little ratty looking but works ok...

[galaxiex]

Original baffle is rough...

Original speaker needs a re-cone...

[tubenit]

How do you want it to sound different then it does?   I say this respectfully ……… you've sort of posted something like
"I have an amp.  I want it to sound different then it does.  Please help." 

Possible mods might be change values of plate/resistor ratio ……….. OR add cathode caps.

With respect, Tubenit

[galaxiex]

How do you want it to sound different then it does?   I say this respectfully ……… you've sort of posted something like
"I have an amp.  I want it to sound different then it does.  Please help." 

Possible mods might be change values of plate/resistor ratio ……….. OR add cathode caps.

With respect, Tubenit

Thanks, not done posting... mods already made... more to come... :)

This is to document the mods I made. 

[galaxiex]

First mod... a new speaker and baffle...

[galaxiex]

I found some schematics online, but they all have the same mistake.

The 220K grid leak resistor is in the wrong place.

[galaxiex]

Redraw of the schematic...

[galaxiex]

Inside is fairly clean...

[galaxiex]

Added a 3 wire grounded power cord and clipped the death cap...

[galaxiex]

Unhooked the original cap can and added 3 new electro caps for the power supply...

Also added a speaker jack...

[galaxiex]

After much experimenting I ended up with these circuit mods...

Grid stoppers R3, R7, R11

Bypass caps C2, C5

Compare to original schematic redraw above...

For reference:
B+ 275V
Screen 260V
Pre 160V

HTR 6.4 AC

[galaxiex]

The mods turned this amp into a distortion monster...

Maybe not everyone's cup of tea, but I like it. 

The grid stoppers are ABSOLUTELY necessary, as the amp will squeal and oscillate without them.

Sorry no sound clips, I have no way to record it.

Pic of the mods...

[galaxiex]

Now I'm looking for an 8 ohm output transformer as the original died, so I installed a Champ replacement TX that is 3.2 ohm.

The Warehouse speaker is a 4 ohm, but I'd like to be able to plug this into an 8 ohm cab.

Also 8 ohms would give me more options for the in cab speaker.

Any suggestions for an 8 ohm output Tx?

Thanks!

[sluckey]

Look at the Mojo771. Just click the transformers link below this message.

[galaxiex]

Look at the Mojo771. Just click the transformers link below this message.

Thanks!

That looks like just the thing! 

[galaxiex]

Tx ordered, now the wait....

[Papa Jim]

Wow. That was fast. My heads still spinning. 

[sluckey]

Tx ordered, now the wait....

While you're waiting go ahead and heat up your soldering iron. 

[VMS]

Nicely done!


Are the pots linear or log and how do you like that simple tone control?

[galaxiex]

Nicely done!


Are the pots linear or log and how do you like that simple tone control?

Thanks!

The vol pot is (I think) linear and the tone is log.
Not 100% sure, I never checked them.

The tone pot works ok, simple hi-cut.
It's effective enough through out it's range. I find 5 or 6 on the dial works well.
You can get good tones at all settings, depends on guitar and pickups (Tele neck, bridge, both).

Roll off guitar volume and ease pick attack and you can coax clean-ish sounds out of it too. 

[shooter]

Roll off guitar volume

I like the way you think !

The TS on my last build 1-3 dark to bluezy, 4-7 rock, 8-10 more treble
see guitar for the rest 

[PRR]

The mods turned this amp into a distortion monster...

How's the hiss?

The Volume control is out front. So it has full hiss even when turned-down. Some amps do that. Most amps don't. I'm wondering if you notice when you stop playing, or if you care.

[galaxiex]

The mods turned this amp into a distortion monster...

How's the hiss?

The Volume control is out front. So it has full hiss even when turned-down. Some amps do that. Most amps don't. I'm wondering if you notice when you stop playing, or if you care.

A little hissy but actually not bad,
no worse than my 73 Princeton Reverb, and it's pretty quiet.