3 Channel Recto Presence Mod....

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fluff191

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I just modified the Presence pot on the Red channel of my 3 Channel Recto. And while I was at it, I thought I would take a few pics and share a simple How-To on it. Apologies for the cell phone pictures.

1. Remove chassis from headshell via the 4 bolts on the underside of the shell. Its best to remove at least the power tubes and the rectifier tubes so when you flip it over, there is no wieght on the tubes themselves.

2. Locate the potentiometer (will be on your right side when chasis is upside down and front is facing you)

IMG00043.jpg


In this shot you can see it a little better....(the bottom pot)
IMG00044.jpg


3. Ready your replacement pot (Mesa 25k Pot #593737; $1.75)
IMG00045.jpg


4. Simply un-solder the 3 leads going to the pot. You can either unscrew the pot just above it or push its leads to the left and that should give you enough room for your soldering iron. I chose to cut the ends off and strip off some fresh wire for the new pot leads, but thats totally up to you.
IMG00048.jpg


5. Simply re-solder the new pot to the correct leads (they all are in line with their correct terminals i.e. the wires do not cross over eachother).....
IMG00049.jpg


6. Re-install pot without forgetting the small plastic spacer on the shaft (it prevents the chrome knob from rubbing on the chassis) and tighten knob with a 2mm Allen wrench.
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7. Enjoy.

So how does it sound? Incredible. Seriously. I found myself hating the Red channel because I could not seem to dial out certain high end frequencies even with the Presence all the way off. The stock rating for this pot is a whopping 100k, which in my opinion is way too much. The 25k is perfect and will give you a range closer to Channel 2.

The most expensive part was the shipping (surprise surprise) and in total the whole thing cost about $10 and about 20 minutes of time. So if you find yourself liking the Orange channel but wish it had the kick of the Red channel, try this simple mod. You will be very surprised at the difference.
 
great write up! i love reading detailed mods how-to's with lots of helpful pics!

Good job! :D
 
Wow. I think I want to try this once I get better wire the wire and gun. This stuff needs a sticky!
 
No I didn't. My buddies Bias Rite took a dump. :(

Then right after that I bought a Rev. E Recto and was thinking about not doing the mod at all for re-sale purposes. But now I think I will just keep the 3 channel and do the mod when the Bias Rite arrives. I will just make it like a tie-in to your excellent How-To.
 
Hell yeah. Congrats on the Rev. E.

There's absolutely nothing wrong with having 2 Rectos either. I've been wanting to buy another one. I've been thinking about buying a 3 channel head again. If I can find a good deal on one, I just might do it.

BTW, you don't need a bias rite. A multi-meter will work just fine. Just follow the links in the thread, and there's some really good information on how to set bias. FWIW, if you're putting the bias pot on the inside, you're right there to measure the bias anyway. ;)
 
Holy hell! You are totally right! I think I might shoot for next weekend to do the mod.

And yeah I know have 2 Rectos and instantly thought "Gotta get rid of one" cause why have 2? But then I thought "Why not?" haha Save the newer one for gigs or something.
 
awesome post fluff... i think your mod plus the other mod for channel 2 on the roadtser (basically replace all the pots to match the stiletto) would be awesome. You should also try some different NOS tubes in your phase inverter preamp slot. I found going with a mellower tube like a Mullard short plate to smooth things out without loosing the high end.
 
jdurso said:
awesome post fluff... i think your mod plus the other mod for channel 2 on the roadtser (basically replace all the pots to match the stiletto) would be awesome. You should also try some different NOS tubes in your phase inverter preamp slot. I found going with a mellower tube like a Mullard short plate to smooth things out without loosing the high end.

I have thought about going down the NOS route, but simply do not know enough about what is good vs. what is bad to really feel comfortable buying anything, ya know? And does changing out the PI (V5?) really effect it that much? And if so how does it compare to changing out tubes in V1?

I am pretty happy with a set of JJ's in V1-V3 with stock Mesa for V4 & V5 with KT77's and GZ34's...
 
fluff191 said:
jdurso said:
awesome post fluff... i think your mod plus the other mod for channel 2 on the roadtser (basically replace all the pots to match the stiletto) would be awesome. You should also try some different NOS tubes in your phase inverter preamp slot. I found going with a mellower tube like a Mullard short plate to smooth things out without loosing the high end.

I have thought about going down the NOS route, but simply do not know enough about what is good vs. what is bad to really feel comfortable buying anything, ya know? And does changing out the PI (V5?) really effect it that much? And if so how does it compare to changing out tubes in V1?

I am pretty happy with a set of JJ's in V1-V3 with stock Mesa for V4 & V5 with KT77's and GZ34's...

On the Roadster the biggest differences can be found in V1, V2 and V6. I do find a smoother tube in v6 gives overall presence of the amp a smoother, less fizzy quality. A more hi-fi tube yields the opposite. To be honest with you i took some advice from some folks here (Shred, Mav), jumped off the deep end and just read up on what has worked for others in their rectos.

If you have time, this was what i ended up with and why: http://forum.grailtone.com/viewtopic.php?f=24&t=32608

I find more of a difference in changing preamp tubes than in changing power amp tubes and i find once you have the right combo there is no need for any eq pedals and such. Obviously a mod would be a little more drastic change than a tube change but both my lead you to your grail tone.
 
Very good thread jdurso. I have been switching out power tubes like crazy, but I think now reading your thread, I will look into some NOS tubes for sure.

And I have a Rev. E Recto on its way so I will have that wonderful amp to compare it to! Thanks for the advice! I have alot of reading to do!
 
fluff191 said:
Very good thread jdurso. I have been switching out power tubes like crazy, but I think now reading your thread, I will look into some NOS tubes for sure.

And I have a Rev. E Recto on its way so I will have that wonderful amp to compare it to! Thanks for the advice! I have alot of reading to do!

BTW i also use the JJ KT77s and GZ34s
 
fluff191 said:
jdurso said:
BTW i also use the JJ KT77s and GZ34s

Haha well you obviously have good taste in tone then.... :wink:

The KT77's are fantastic tubes with the GZ34's.

Haha yes, yes they are. Even better with a Sylvania short plate in V1 and a Siemens Long Plate in V2. :wink:
 

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