Rivera R55-12 Adjustable Boost Mods

[soundchaser59]

Started here....
http://ivanrichards.com.au/2011/12/16/more-about-rivera-amps-the-ninja-boost-mod/

But that article only describes the Ch.2 Ninja boost mod, the easier mod of the two. I had to scrape the bottom of the internet to find help with the Ch.1 Lead boost mod. (the bold underline sentence is the critical piece of info that allowed me to finally figure out what to do for Ch.1.

If you visit this thread over at tdpri, you can see and hear how these boost mods were done.
http://www.tdpri.com/forum/amp-tech-center/456473-rivera-boost-mods-r55.html

Find Resistor R117 (value is 220k) on the circuit board. Note that Rivera completely replaces Resistor R117 with a one meg pot, this allows a wider range of adjustment (even to more boost than normal). However I just wanted to be able to reduce the amount of boost, so I wired the pot in series with R117. Here’s how I did it. Heat one lead and lift it up using your tweezers or a small screw driver. Take one conductor in the wire and tin the end with solder. Stick it through the hole the resistor came out of and solder it in. You don’t normally have to take the entire circuit board out to do this since it is plated through. Just make sure the wire doesn’t come back out. Another alternative is to snip the resistor lead so enough is left on both sides to solder to. The conductor could be solder to the remaining part of the leg that is in the board.
Take the other conductor in the wire and solder it to the end of the resistor. Make sure you tape off this end or use heat-shrink tubing. Finally, take the shield twist it together and solder it a ground point (I used the ring in the center of V2’s socket).
Now solder the other end of the wire to the potentiometer. Solder one connector to the middle pole on the pot. Solder the other connector to the right outside pole. Cut off any excess shield on this end of the wire. You only need to connect the shield on one end and it is better to connect it near the circuit board as the instructions indicate.
Alternate: An alternate method of doing this is to adjust the normal sound by replacing resistor R116 with a resistor and 1 meg pot. The value of the resistor depends on how close to normal you want to be able to go. To start with dead stock, use a 1.2 meg resistor in series with the 1 meg pot. This will allow you to get halfway to the stock Ninja Boost setting in normal mode. You can use a lower value for the resistor or eliminate it altogether and just use the 1 Meg pot to start closer to the Ninja sound. This makes channel 2’s normal sound more like a hot-rodded Fender sound. SRV fans might like this variation. I got this idea that from Rivera users who use Channel 2 with the Ninja always on, because they prefer that tone more. The alternate mod lets you get close to that sound all the time, while retaining a boost option.

Channel One Boost Ideas
The Channel One Boost Mod is the same as the Ninja Boost mod but the resistor is different. On an R Series amp there is no resistor. On an original Knucklehead the Boost resistor is R160. On the R Series amps (like the R-55, R-100, Suprema and Chubster), the Jake Studio Combo, Fandango and Quiana the R-160 resistor is not there. To do the Mod you’ll need to find the leg of photo-resistor PH106 that attaches to the junction of R119 and R130. This leg would go to one conductor of the wire going to the potentiometer, the other conductor of the wire goes to the junction where you removed the leg of the photo-resistor. This is not a mod for a novice as you could ruin the photo-resistor if you make a wrong connection.

 

[soundchaser59]

The schematic is here.....

http://www.freeinfosociety.com/elect...erarseries.pdf

 

[soundchaser59]

(sorry about my poor photo skills)

Holes drilled....

Continuity for PH106 to the junction of R130 and R119....

The two pots mounted to the chassis, just behind the input jacks....

Leads attached to one leg of PH106 (vactrol)......R130 (2.2M) is replaced and new, the old one appeared scorched.

R117 lifted at one end (the blue resistor standing up straight), a piece of resistor lead in the other hole, make a hook in both ends, and attach the leads for pot #2 Ninja adjust to the hooks.

Both sets of leads in place, with shrink wrap for stability....

the pots again, now attached to the boost circuits.... I will set to taste and leave it alone.

If I were going to do it again, I would use 2M or maybe even 4M or 5M ohm pots. These 1M ohm pots are not quite enough ohms to completely nullify the boost. I still get a small boost even with the pots on full resistance (full counter clockwise). In fact, it's almost the perfect amount of boost for my taste, with the pots fully engaged. Full clockwise gives me the original over the top boost level.

 

[soundchaser59]

I recorded a short demo of the changes. I recorded a bit on both channels, no boost, the original boost, and my adjusted boost, and I'm pretty sure you'll be able to tell the difference. I'm totally convinced now that this is a very necessary mod on these amps. I believe the Knucklehead also would benefit greatly from this same mod. (There is a Knucklehead 55 for sale right now, and I can't afford it. Darn It! That K55 was my all time favorite amp!)

 

[soundchaser59]

Here is a 40MB wav file that demonstrates the change to the boost levels.

http://www.soundchasermusic.com/demos/rivera_boosts.wav

Download it before you play it, as wav's tend to not stream very well.

Here is roughly what you are hearing...... I like to push the gain to the edge just before breakup, so my "clean" sound is not crystal sparkly clean like you may expect.......but the Rivera amps will do a crystal sparkly clean if you desire it.

ch2 clean (boost off)
ch2 adjusted boost (about 1/3rd of the pot's range)
ch2 full boost turned up, then back off
ch2 clean
ch2 adjusted boost

(approx at 2:07)
ch1 lead no boost (boost off)
ch1 lead adjusted boost (boost on, but pot fully counterclockwise)
ch1 full boost (pot full clockwise)
ch1 adjusted boost
ch1 no boost
ch1 adjusted boost

You should be able to easily recognize when the full boost level is on, it's pretty clearly different than the rest of the sounds.

No fx, no OD pedals, no processing, just the raw wav recording, reverb is the 3-spring tank in the amp, fx loop is patched with Send = 7 and Return = 3, JJ 5751 in the V1 slot, Weber Amsterdam speaker, EV BK1 + Sennheiser E906 mics on the grill at speaker edge, this is a G&L ASAT Z3 telecaster.

 

[Bedeaich]

I had to scrape the bottom of the internet to find help with the Ch.1 Lead boost mod.

I wouldn't quite describe asking and recieving the friendly help you got from the folks on the TDPRI forum as scraping the bottom. If you appreciate good advice, please note that people who freely choose to help, do so to pull others up, they are not bending over to facilitate others to climb up on their backs.

 

[soundchaser59]

I wouldn't quite describe asking and recieving the friendly help you got from the folks on the TDPRI forum as scraping the bottom. If you appreciate good advice, please note that people who freely choose to help, do so to pull others up, they are not bending over to facilitate others to climb up on their backs.

You are known as Bendyha over at tdpri. You provided the great photograph that showed the point for the Ch. 1 mod to connect, and Marshman provided a doc to me that was the final piece of information that made me realize how to complete the mod.

Here is the link to that thread.
http://www.tdpri.com/forum/amp-tech-center/456473-rivera-boost-mods-r55.html

Here in the USA the phrase "scraping the bottom of the barrel" (which I modernized to say "scraping the bottom of the internet") is not derogatory, as I think you have interpreted it. Its general meaning is "I looked everywhere for a long time (9 months) and I had to turn over every last leaf and stone - I had to 'scrape the bottom of the barrel' for every last bit of information - before I finally found the right answers and the right kind of help." It's akin to scraping the bottom of a jar to get every last bit of food out of it.

Your English was so good over at tdpri that I assumed you must be an American who has relocated to Europe. Maybe I was wrong. I believe if you were American you would have understood the colloquialism and it would not offend you. If you are not American then I should not expect you to get the reference. It was not a cut down.

 

[Bedeaich]

To be reduced to ones last resources. The term alludes to the barrels of salted meat lined and sealed with fat, the pre-canning provisions for sailors. When all else was used up the crew had to resort to trying to survive on the then dry and rancid fat they could scrape from the discarded barrels - this is maggot and rat **** teritory. The term predates America.

 

[soundchaser59]

To be reduced to ones last resources. The term alludes to the barrels of salted meat lined and sealed with fat, the pre-canning provisions for sailors. When all else was used up the crew had to resort to trying to survive on the then dry and rancid fat they could scrape from the discarded barrels - this is maggot and rat **** teritory. The term predates America.

If you say so......I was never taught that, never heard it used that way, I explained what I meant, you can take it your way if you want. Thanks for the history lesson and the circuit assistance.

 

[Bedeaich]

If you say so......I was never taught that, never heard it used that way, I explained what I meant, you can take it your way if you want. Thanks for the history lesson and the circuit assistance.

Come on ....... now you are unnecessarily adding insult to injury. Run a check on the idiom, see if you can find any examples other than negative or derogatory ones. I couldn't.
"You are known as Bendyha over at tdpri. "
If a person chooses to retain individual and separate personas for reasons of their own choise, it should be with respect and discretion that others acknowledge this.

 

[soundchaser59]

If a person chooses to retain individual and separate personas for reasons of their own choise, it should be with respect and discretion that others acknowledge this.

Similarly, this is not the experience I have encountered with people who have different names at different forums, and yet another name on ebay. My experience has never been good with that......but you are an exception, so I thank you for being a good guy behind all of your names.

If you want to maintain that kind of separation, you need to use a different email address for each forum. You'd be surprised what google will bring up on people just by using what's in the public profile info, sometimes nothing much, but other times a lot more than they realize. I've backed out of transactions before based on what I learned thru a google search. It was very different than the image the seller was putting up here on the forum. I think I get an extra bit of credibility in my sales simply because I have the same screen name everywhere.

This was the only forum where I did not link to the original tdpri thread for the mods you guys helped me with. Sorry about the misunderstanding with how I used the phrase. No slight or offense was ever intended.