NUAD! Rivera R Fifty-Five Twelve - circa 1993

[tbonesullivan]

So, this is the end result of me looking for a versatile EL34 amplifier that is relatively portable. It's in INCREDIBLE condition for an amplifier that is around 25 years old. Also, the initial build quality of Rivera amps is honestly pretty dang high, even for a PCB amplifier. It's well put together, well thought out, and has a variety of tones it can produce. I have only begun to really explore what it is capable of.  It may be a bit small, but I always have a 2x12 I can plug it into if I want to really want to push some air. Anyway, The pictures:

Front:

Back:

 

As you can see, it's in REALLY good shape. There were some sticky issues that I had to take care of, such as for some reason the/a previous owner put some duct tape around the edges of the rear baffle, which had become a sticky mess. Goo gone and rubbing alcohol to the rescue!  The control layout is kind of "British" for channel 1, and "American" for channel 2. Both channels have a good amount of gain, but the British channel definitely has a bit more. The EQ is also in B M T order, though I don't know if the circuit is that way as well. The Volume has a pull "boost" which makes it louder and hairier. Definitely not a quiet channel.

Channel 2 is more subdued, but can get pretty crunchy. It's voiced like a Fender Tweed amp in terms of the Tone Stack, and has a Bright switch. It also has a "notch" switch on the mids, that switches the notch from 500hz to 250hz, which is the Fender Blackface tone stack. There is also a "Ninja" boost on the volume, which puts in some more gain, and thickens up the channel overall.

The presence and reverb are overall controls, and help set the feel of the amp. Only real downside is that the reverb cannot be turned off by the footswitch, but usually I like the same amount of reverb on all channels, so it's not a biggy. The footswitch does switch channels, and also controls the Boost and Ninja modes.

The amplifier came with all stock tubes, which were Siemens / RFT EL34s in the power section, which I decided to keep, as they work fine. The preamp tubes had a Sovtek 12AX7WA in the V1 slot, and the other 4 were all 80's Chinese Beijing Factory 12AX7As with the Square Foil Getter. I swapped these out for a Mullard Reissue CV4004 in V1, a CBS-Hytron JAN-12AX7 in V2, an EHX 12AX7 in V3, and a Sovtek 12AX7LPS in the V5 phase inverter. I kept the Chinese in the Reverb slot, as it was working fine. All preamp tubes have shields, which I guess is a bit overkill. This also means it's very hard to swap preamp tubes when the chassis is in the amp.

Chassis Layout: V1 on Right

 

 

Preamp tubes: old on top. new on bottom:

 

 

I haven't been able to find out much about the CBS-Hytron 12AX7 in terms of sound. You see them around, but they definitely don't have the desirability of the major name preamp tubes. I may replace it with a Sylvania Long Plate or other ANOS tube later on. I've also got some good new production tubes to throw in.

Now, one thing I'd like to mention again is just the level of quality in the build. The rear baffle is not held on with wood screws: it's held on with machine screws that go into T-Nuts on the other side of the mounting blocks, like a speaker. No split wood or screw holes like on my Marshall.  There also is shielding on part of the top of the cabinet, and foam on the rim of the chassis.

 

The only downside with the foam is that after 25 years, the adhesive had kinda melted, and was getting everywhere, so I managed to clean it off and replace it, which took an hour of work. UGH.

The old foam and some goooo:

 

The goo on the cabinet:

 

And gone. Nice shot of the guts too:

 

And foam back on. I also now have a TON OF FOAM that I'll be using on other amps, which also have foam that has gotten crushed over the years.

[DetroitBlues]

Ninja Boost?  Now that's different!

Amazing how much is crammed into a small space.  How much does it weigh?  

[tbonesullivan]

47lbs according to the manual. It feels lighter than that though. Could be how it is balanced. It's a little bit smaller than my Mesa Boogie DC-5.  It's 18 inches tall, 21 inches wide, and 10 inches deep.

[Yooper]

Thanks for the tour of a neat amp. My Champ II is reason enough to want to check out any Rivera amp.

Looks more versatile than a DC-5. (And I love my DC-5 to bits.)

[tbonesullivan]

6 minutes ago, Yooper said:

Thanks for the tour of a neat amp. My Champ II is reason enough to want to check out any Rivera amp.

Looks more versatile than a DC-5. (And I love my DC-5 to bits.)

The DC-5 has the Graphic EQ though. However I wish the clean channel with the boost pulled out and mid's dimed had more bite. The way the manual describes it is a far cry from what it actually is. Still, it's a great amp in its own right, especially with the MV mod.

[Yooper]

There's no mids like Mesa mids.

Rivera fuses a decent Mesa/Fender hybrid quite well.

[JeffB]

Cool amp.  Hope it fills the spot you want it to. Congrats.

[Gitfiddler]

That's a lot of amp in a small package.  Rivera products always seem to me like 'Fender amps-on-steroids'...in a good way!

Enjoy that new rig!

[tbonesullivan]

1 hour ago, Gitfiddler said:

That's a lot of amp in a small package.  Rivera products always seem to me like 'Fender amps-on-steroids'...in a good way!

Enjoy that new rig!

They definitely are! Paul Rivera first really made his name when Fender brought him in to design the Champ II, which they wanted to compete with Mesa Boogie amps, which were based off of modified Fender amplifiers. Rivera was another guy who was hot rodding amplifiers, so they brought him on for a while. Then he also started his own amplifier company, and in the 80s they put out some seriously powerful and high gain amplifiers, like the M-100. It's a BEAST.

[Yooper]

 

6 hours ago, tbonesullivan said:

They definitely are! Paul Rivera first really made his name when Fender brought him in to design the Champ II, 

Here it is. Same cab size as a silverface Champ, but a lot more punch, attitude and snarl.

 

[CJTopes]

I have a Rivera Chubster 45. I believe it was based off the 55 /12.  Great amp. as a matter of fact I've bought two Riveras since. 

[tbonesullivan]

The Chubster and R-series are pretty much the same design. The manual I have is for the 30-12, the 55-12, the 100-212, the Chubster 40, the Chubster 55,  and the Suprema 55.  It's a great design,  and they've really gotten some great variety out of it.

[212Mavguy]

Great Post!  Nice amp.  CBS HYTRON?   Think GE longplate.  Great tones for cleans, mid gain blues, less mid scooped than the gray long plate Sylvanias, similarly microphonic.  I think that the CBS Hytron variant is a great sounding tube.  The sylvania has more snarl when pushed into the dirt.  Try to find a couple green print GE 5751's...they will be great in that amp, long lasting and not hugely expensive for what they do.

[tbonesullivan]

Yeah, many said they have a nice great clean sound. I think the Rivera is a bit too much of a beast for it. I've had very good luck with the Sylvanias in a Mesa Boogie DC-5.

I also however have an RCA gray shortplate and gray long plate. Also a Tungsram Hungary made tube, and a few others. I try to put a bit of old glass in all my "nice" amps. I think I'm going to switch the tungsram into the Rivera, and move the Hytron into something lower gain. I've got another CBS Hytron as well.

The only issue really is the long plates on a lot of the old tubes, which means V1 can be an issue. On amplifiers like the maverick use completely different tubes for each channel. V1 is all Rhythm, and V2 is all lead. So, Especially since it's a como, I'm kinda stuck with using short plate tubes, and most of the ANOS tubes I have are long plates.

The Rivera and DC-5 both have a Shared V1, so I can put a nice solid new production tube there. Planning tube layouts is hard. Dang.