It is currently Tue Mar 17, 2020 1:27 am

All times are UTC - 7 hours



Post new topic Reply to topic  [ 11 posts ] 
Author Message
Post subject: Another Twin Mod Question...
Posted: Mon Nov 05, 2012 7:32 am
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Mon Feb 08, 2010 9:40 am
Posts: 987
So I'm curious about this mod I also discovered... but need to get it better explained in idiot-proof terms so I actually do it right.

Use normal channel for reverb control – Adjust EQ and depth of reverb.

This mod is relevant only for two-channel amps with normal and vibrato channel. This trick is great for the reverb enthusiasts among us, and who is not? Plug your guitar into the vibrato channel, then unplug the reverb return cable on the back of the amp (the one that comes from the reverb tank output) and plug it into the normal channel input. You will need a converter to go from male phono/RCA jack to a 1/4″ male jack. You may now use the normal channel as a reverb control where you can adjust the depth and tone using the volume, bright switch, treble and bass knobs (and mid if you have a Twin Reverb). The reverb knob on the vibrato channel will have no effect any longer.

This mod is not applicable together with the Pull V1 mod, as you need the normal channel preamp tube.


So my question is this... do I need to unplug both of the RCA cables at the amp, or just the red or white one? Which is the return cable... or does that refer to both the red and white or one or the other... sorry, it's early, and I'm not forming complete coherent thoughts and sentences yet, but I was hoping to get this up and posted so when I get home from work one of you may have had a chance to respond. Cheers.


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: Another Twin Mod Question...
Posted: Mon Nov 05, 2012 3:22 pm
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Mon Feb 08, 2010 9:40 am
Posts: 987
So I think I have this figured out but PLEASE someone jump in to correct me in case I've gone astray... I'll be waiting before I power up to get confirmation that I'm on the right track.

From all that I can figure out, the RED RCA cable is the output from the reverb tank to the amp chassis. I'm going to be soldering my own cable, with a female RCA at one end, and a 1/4" at the other. I am then going to attach the male to female RCA and then plug the 1/4" into the input of the Normal Channel on the amp.

:?: So does this look right :?:
1) Unplug red RCA from bottom of the amp chassis
2) Attach red female RCA to red male RCA
3) Plug 1/4" into Normal channel of amp
4) Cross fingers...


Top
Profile
Post subject: Re: Another Twin Mod Question...
Posted: Mon Nov 05, 2012 4:15 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
You know the output impedance and the voltage is quite a bit different between a guitar pup (passive type) and the reverb section of your amp.

Does the mod take this into account?


Top
Profile
Post subject: Re: Another Twin Mod Question...
Posted: Mon Nov 05, 2012 4:24 pm
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Mon Feb 08, 2010 9:40 am
Posts: 987
Quote:
You know the output impedance and the voltage is quite a bit different between a guitar pup (passive type) and the reverb section of your amp.

Does the mod take this into account?


Good question... all I know is what I found on the website, listed in my first post that's in blue font. The information and mods came from this site http://fenderguru.com/amps/twin-reverb. I'm not very savy when it comes to amp mods, amp wiring, impedance, or how it all works... I can wire up guitars (with the help of diagrams) but all this amp stuff is new to me.


Top
Profile
Post subject: Re: Another Twin Mod Question...
Posted: Mon Nov 05, 2012 4:37 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
I think you should leave the amp alone and use it as designed. :wink:

_________________
Bill

Image


Top
Profile
Post subject: Re: Another Twin Mod Question...
Posted: Mon Nov 05, 2012 4:47 pm
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Mon Feb 08, 2010 9:40 am
Posts: 987
Quote:
I think you should leave the amp alone and use it as designed.


Oh, c'mon... where's the fun in that. :D Seriously though, I don't want to frig the amp up but if it's not going to hurt the amp (or electrocute me) I'd be curious to try it. I simply don't know enough about amps to know, which is why I'm here asking. I do appreciate your thoughts though, I probably would be better off just leaving it be, but I'm too prone to tinkering for that to ever happen :lol:


Top
Profile
Post subject: Re: Another Twin Mod Question...
Posted: Mon Nov 05, 2012 4:55 pm
Offline
Rock Star
Rock Star

Joined: Mon Apr 05, 2010 2:37 pm
Posts: 8708
Location: Natural Bridge, Virginia
JamGuy wrote:
Quote:
I think you should leave the amp alone and use it as designed.


Oh, c'mon... where's the fun in that. :D Seriously though, I don't want to frig the amp up but if it's not going to hurt the amp (or electrocute me) I'd be curious to try it. I simply don't know enough about amps to know, which is why I'm here asking. I do appreciate your thoughts though, I probably would be better off just leaving it be, but I'm too prone to tinkering for that to ever happen :lol:


I would pay heed to BMW's comment. If not careful you could end up overloading the front end of the amp.

_________________
Bill

Image


Top
Profile
Post subject: Re: Another Twin Mod Question...
Posted: Mon Nov 05, 2012 5:53 pm
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Mon Feb 08, 2010 9:40 am
Posts: 987
Quote:
I would pay heed to BMW's comment. If not careful you could end up overloading the front end of the amp.


Fair enough... and again, I appreciate everyones input, that's why I was asking. It sounds like a risky endeavor and the last thing I want to do is fry my amp. I can find something else to tinker with!

I have to ask then, what about the other amp mods listed on this page http://fenderguru.com/amps/twin-reverb.... are they all a little sketchy? I recognize that these are probably designed for old blackface and silverface twins, not reissues... is that where some of the problems lie? Amp mods do seem like something I'd enjoy exploring but perhaps I should pick up an old silverface champ or something to experiment on. Cheers.


Top
Profile
Post subject: Re: Another Twin Mod Question...
Posted: Mon Nov 05, 2012 6:02 pm
Offline
Amateur
Amateur

Joined: Tue Aug 23, 2011 3:13 pm
Posts: 108
I've read of another way of doing what you are asking. It involves a wiring change that isn't too difficult. It's called the "Fritz's mod".


Top
Profile
Post subject: Re: Another Twin Mod Question...
Posted: Mon Nov 05, 2012 6:21 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
I presume you want to increase the range of control of the reverb and tremolo portions of the amp. You know, a delay pedal maybe worth a try. At least for the reverb issue. Sure is a lot less invasive.

In essence with that Fender guru mod, you are putting a single-ended 12AT7 amp in front of your input jack. That's all the reverb portion of your TRRI is. A 12AT7 SE amp driving the spring tank. With a 12AX7 recovery-output stage.

That's potentially 2-watts with 15k-ohm impedance onto the input 12AX7 of your amp. Better use a very good military spec'ed tube. Or buy a bunch of Sovtek 12AX7s.

http://www.mif.pg.gda.pl/homepages/fran ... /12AT7.pdf

Like Rockerduck said, there are several better ways to achieve the end result you want.


Top
Profile
Post subject: Re: Another Twin Mod Question...
Posted: Mon Nov 05, 2012 7:21 pm
Offline
Aspiring Musician
Aspiring Musician
User avatar

Joined: Mon Feb 08, 2010 9:40 am
Posts: 987
Thanks... I think I'm going to let it rest for now. Maybe I'll revisit the idea when I have more time... this all may have been a major effort on my part to distract myself for the massive paper I've been procrastinating on. The gigs up... it's due tomorrow and I need to get crackin' on it :(


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 11 posts ] 

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: