Interested in learning how to add an additional tube gain stage

[Ed_Chambley]

I have a amp, version of a 5f4, which when I built it I added an additional 9 pin socket for future use.  Are they inserted before v-2 or after.  Do they have any tone controls.  Basically I am asking what can be accomplished with an additional gain stage.  Also the turret board does not allow for this.  In this case do you make a small board and mount it close to the area of hookup. Of course I will make it switchable, maybe even foot switchable. 

Can you achieve different voicings?  Can you add lots of preamp distortion and is this the main reason people add additional Gain stages.  I assume you can do anything you want.  Can it be used to add a single tone control such as a 5e3 if V-2 were switched out of the circuit?  I know it wont sound like a 5e3, I am just looking for some input of good uses and implementation of an additional gain stage.  A new learning experience. 

I initially planned it for a future reverb, but I heard a dedicated fender reverb unit and IMO this is the nicest spring reverb I have ever heard so I will build this for spring reverb.  Bruce Collins suggest a verbzilla by line 6 for tweed amps.  I picked one up the other day off ebay and he is correct, it is a very nice unit.  I mention this as these thing have changed my mind for the original plan for the additional tube socket.

[phsyconoodler]

How about tremolo?I really doubt you will like the extra gain on a 5F4.
You can graft in a Vibrochamp trem circuit.With an extra gain stage you will need a gain control anyway,so a speed control for trem shouldn't be a stretch.Or take a look at some old amp schematics for something like that.
  An extra gain stage on a Tweed amp? Yuck! IMHO!

[kagliostro]

What about a simply mod

V1 12ax7 instead of 12ay7

and/or

V1 paralleled ?

also look to Tubenit's Tweed Overdrive Special

a 5879 is a good tube to add

Kagliostro

[tubenit]

Just an idea to consider. I did something similar to this on the Double C amp I built for a friend.

This sound clip on the Double C uses this gain stage idea:
http://www.soundclick.com/player/single_player.cfm?songid=10391428&q=hi&newref=1

This schematic may not be completely accurate to a 5F4.  I grabbed a 5E7 and quickly edited it.

Hopefully you get the idea of how to add a gain stage. If I attempted this, I'd use a terminal strip.

With respect, Tubenit

[tubenit]

You could also experiment with a 5879 in the V1 position as was already suggested and do something like this.  Note I "borrowed" an input jack to do this.

With respect, Tubenit

[Ed_Chambley]

How about tremolo?I really doubt you will like the extra gain on a 5F4.
You can graft in a Vibrochamp trem circuit.With an extra gain stage you will need a gain control anyway,so a speed control for trem shouldn't be a stretch.Or take a look at some old amp schematics for something like that.
  An extra gain stage on a Tweed amp? Yuck! IMHO!

I agree with you about the extra gain on a tweed.  This amp is one I experiment with, so it really not a 5f4 anymore.  That is just what it began as.  I have a 5f4 which I added tremelo and it is very nice.  It is learning I am interested in, not really the outcome.  Granted the result is what is most important, but first I must learn.

[Ed_Chambley]

What about a simply mod

V1 12ax7 instead of 12ay7

and/or

V1 paralleled ?

also look to Tubenit's Tweed Overdrive Special

a 5879 is a good tube to add

Kagliostro

I change tubes often for different tones and sometimes to accommodate the size room I am playing.  My favorite tube in a tweed, V-1 is a 5751, but I have used a 12Au7 to play smaller rooms.  This is because I prefer amps with 2 different voiced speakers.  I am very interested in the TOS and am planning to build one soon.

[Ed_Chambley]

Just an idea to consider. I did something similar to this on the Double C amp I built for a friend.

This sound clip on the Double C uses this gain stage idea:
http://www.soundclick.com/player/single_player.cfm?songid=10391428&q=hi&newref=1

This schematic may not be completely accurate to a 5F4.  I grabbed a 5E7 and quickly edited it.

Hopefully you get the idea of how to add a gain stage. If I attempted this, I'd use a terminal strip.

With respect, Tubenit

This is what I am interested in.  Where is the original schematic before the added gain stage so I can compare what was done.  It looks fairly simple, but there are a couple of resistor connections I do not understand.  Is it in Dougs library and it is a 5E7?

[tubenit]

Where is the original schematic before the added gain stage?

http://www.el34world.com/charts/Schematics/files/fender/SUPER_5F4.pdf

I don't have a SCH "original editable" schematic.

With respect, Tubenit

[Ed_Chambley]

Where is the original schematic before the added gain stage?

http://www.el34world.com/charts/Schematics/files/fender/SUPER_5F4.pdf

I don't have a SCH "original editable" schematic.

With respect, Tubenit

Thank you.  This should work out just fine.

[tubenit]

I had a few minutes to make an editable version.  When you finish your project, perhaps you will share what you finally ended up with.

With respect, Tubenit

I also have drawn a layout for the OD using a terminal strip with 4 terminals.  The "OD to" &  " OD from"  refer to wires going to the OD (from the DPDT) &  from the OD ( to the DPDT).

IF you wanted, you could use the smaller mini-pots and mount them on the back of the chassis in a "set & forget".

[Ed_Chambley]

I had a few minutes to make an editable version.  When you finish your project, perhaps you will share what you finally ended up with.

With respect, Tubenit

I also have drawn a layout for the OD using a terminal strip with 4 terminals.  The "OD to" &  " OD from"  refer to wires going to the OD (from the DPDT) &  from the OD ( to the DPDT).

IF you wanted, you could use the smaller mini-pots and mount them on the back of the chassis in a "set & forget".

Thank you for taking the time to do this for me.  As I mentioned, if began as a 5f4 long ago.  It was my first build.  I cannot remember everything I have done to it.  It is fairly noisy as I have no underboard wiring and has clips soldered to turrets to swap out caps so I could learn what cap changes do and some resistors as well.  It does have a long tail phase inverter so it is definitely no longer a 5f4.  The chassis is 17 x 10 x 4 with a removable bottom, face and back.  I will be happy to share the results, but usually the results end up in another amp.  Right now it is like a JCM 800 with a Blackface tonestack.

[tubenit]

It does have a long tail phase inverter so it is definitely no longer a 5f4.  The chassis is 17 x 10 x 4 with a removable bottom, face and back.  I will be happy to share the results, but usually the results end up in another amp.  Right now it is like a JCM 800 with a Blackface tonestack.

WHAT!!!  

You rascal!!!!    Why didn't you say that up front?    
 

I already had several  Marshall Plexi with OD   idea drawn up complete with layout in the SCH files:
http://www.el34world.com/Forum/index.php?topic=10776.0

These ideas take the Marshall topology and simply add a switchable OD to it.

With respect, Tubenit

And here is another idea also that has Marshall-ish topology with an OD added.  OR you can look at Hoffman's  "Hot Switch mod" in his Library of information.

[Ed_Chambley]

It does have a long tail phase inverter so it is definitely no longer a 5f4.  The chassis is 17 x 10 x 4 with a removable bottom, face and back.  I will be happy to share the results, but usually the results end up in another amp.  Right now it is like a JCM 800 with a Blackface tonestack.

WHAT!!!  

You rascal!!!!    Why didn't you say that up front?    
 

I already had several  Marshall Plexi with OD   idea drawn up complete with layout in the SCH files:
http://www.el34world.com/Forum/index.php?topic=10776.0

These ideas take the Marshall topology and simply add a switchable OD to it.

With respect, Tubenit

And here is another idea also that has Marshall-ish topology with an OD added.  OR you can look at Hoffman's  "Hot Switch mod" in his Library of information.

The reason I did not mention it is it may not be the same thing tomorrow.  I am constantly changing it and messing with it.  What I am wanting to learn is how additional gain stages are implemented.  I have looked at the Hot Switch Mod and Learned some things, but please understand, if I were to attempt this I would not know where to begin and why it would be different in different applications.  But not now, with the info you have given me I will continue.