5E3 Pre PI Master Volume

[waldner]

One more mod question on the 5E3.  Again I have built the Hoffman version and it's fantastic.  I have now been playing with a Weber attenuator and it works fine, but it would really be nice to use this pre phase inverter master volume that is shown as a mod to the traditional 5E3 Fender layout here: https://robrobinette.com/5e3_Modifications.htm#Add_Master_Volume

Here's his description which talks about advantages of doing it this way on the 5E3 in particular:

With the 5E3 you can put the Master Volume before or after the phase inverter (tube V2B) with good effect because the 5E3's cathodyne phase inverter puts out approximately unity gain (no actual gain) which means it doesn't amplify the signal so the Master Volume can go before or after it. Placing the Master Volume before the phase inverter (PREPhase Inverter Master Volume) will allow you to control the amount of the 5E3's infamous phase inverter overdrive 'double frequency' distortion at high volume levels or when using pedals that boost the input signal. Preventing the phase inverter from going into extreme frequency doubling distortion can result in a much sweeter, tastier overdrive tone. Phase inverter double frequency distortion is the reason why high gain modifications to the 5E3 are not popular (see my Cascaded High Gain Channel Mod below). With a PRE Phase Inverter Master Volume you can easily dial in how much phase inverter distortion gets through to the power tubes. If you like to use fx and pedals, especially boost pedals for distortion, I recommend you use this PRE PI Master Volume. It will make the 5E3 much more pedal friendly because the 5E3's phase inverter distortion can make a mess of reverb, delay and boost effects.

Could anyone help me convert this to Doug's 5E3 layout?  I'm not so good at schematics and could use a transcription that is more paint by numbers. 
Note I have attached two ways he shows of doing it to the standard Fender 5E3.  How well does this translate to Doug's?

[Champ_49]

Yup. I am currently thinking about doing this mod as well. Pre phase inverter. Only thing I was confused was he didn't jumper the input jack ground Lugs. Not sure if you have to do this, but id think you should?  As of now om assuming its ok to just not jumper them because the inputs are touching the chsssis anyways so I'm a bit stuck here. But it would be nice to do this mod. I'm thinking of building another 5e3 so I can do all these mods as well as the gain mod. I already built a 5e3 all stock.  Going to try to keep that one like that.

[waldner]

Yes Champ, I'm not sure about the input jacks either.  I am finding some magic in the 5E3 that is not really present in any of my other amps (and I have a lot of amps).  So I am trying to give the 5E3 some more flexibility/versatility.  I recently added switchable negative feedback which is nice when you want to tame and clean the amp up.

I'm intrigued by the pre PI master in part because of the claim that it will also sweeten things by reducing the double frequency distortion and make the amp more pedal friendly, which could be really nice when the neg. feedback is in play and things are cleaner.  I also like that when you turn the master all the way up it's basically like you are back to a non-master 5E3.

I'm just not sure how to implement it on the Hoffman layout I built.  I don't want to blow up my lovely 5E3:)

[kagliostro]

I think it is correct, but revise





K

[waldner]

Excellent.  Thanks Kagliostro.

[waldner]

Kagliostro and anyone else who may be interested,

I did this mod last night and have been playing with this master volume and it works!  It's pretty cool.  It allows you to turn down and still get good tone and does seem to modify the heavy distortion profile as described above to some extent when running the normal volume way up and just turning the master down slightly.   It's also true that the amp seems pretty much back to stock with the master volume all the way up.   I prefer the mods that let you get back to the stock sound at the flip of a switch or turn of a dial.

I used a 1 Meg audio taper pot and still the range of usable master is pretty small.  It's works nicely with the feedback switch mod I did previously, though the feedback doesn't have as much effect at lower master volumes (as you might expect).

The 5E3 is such a good sounding base for all of these modifications and options that it makes me want to try a few more.  Rather than build a 5E5 Pro or A, I think it might be nice to just build a more powerful 5E3 with as little other changes as possible.  I understand that just putting 6L6 tubes in won't do much, but larger transformers, 6L6's and a different rectifier would?  How close could one build a more powerful version while staying as close to the Hoffman 5E3 as possible.

[Champ_49]

That's cool!

I'm thinking of another 5e3 build with these mods on my next amp.
After finishing the jcm800 this will be my next attempt. 

[sluckey]

How close could one build a more powerful version while staying as close to the Hoffman 5E3 as possible.

Look at the 5E5.

[kagliostro]

5E3 to 5E5

      

Looks a lot of work to do, the schematics are totally different

 

K

[Willabe]

No there not. 5E5 has 1 extra 12AY7 tube that's it. Just loose the extra tube.

It was the big brother to the 5E3. Same 2x volume and single tone control.

5E5A was totally different.



                 Brad   

[kagliostro]

If you use only 1 x 12ay7 the differences are limited to the value of 3 resistors and the W dissipation of one resistor

of course the tube rectifier and transformers

K

[waldner]

Here's a version that Ceriatone calls the 5X3 with a bigger PT, 6L6's, GZ34 and a few parts value changes.  I'm guessing I could apply this to Doug's layout.  I'd just need to pick the right PT and OT. 

http://www.ceriatone.com/images/layoutPic/fenderLayout/5X3Ceriatone.jpg

[kagliostro]

I've just find this (on your link)

https://robrobinette.com/5e3_Modifications.htm#6L6_Upgrade

K

[waldner]

Yes, I was looking through all of that thinking about my next build.  Part of me wants to build a larger 5E3 (5X3, 5E5, 5E5A etc...) because I like the magical squishy warm sound of the 5E3 but wish it could keep up with a drummer and band better.  Another part of me thinks I should build something else next. 

I was, starting 10 years ago, planing to work my way through building all of the classic guitar amps of the 50s and 60s.  I have completed a champ/ga5, 18 watt, 5E3 and most recently a 5f6a.  So now I'm thinking maybe I should build an AC30? 

[kagliostro]

Listen to the Gibson GA80 varitone


https://www.youtube.com/watch?v=iFDd51enJkQ


if you like, here is the schematic





K