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NUAD! Rivera R Fifty-Five Twelve - circa 1993


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So, this is the end result of me looking for a versatile EL34 amplifier that is relatively portable. This was at BCR music, so I drove out to test it out, and took it home.  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:

rivera01.jpg

Back:

rivera02.jpg

 

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

 

rivera04.jpg

 

Preamp tubes: old on top. new on bottom:

 

rivera03.jpg

 

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.

rivera05.jpg

 

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:

rivera06.jpg

 

The goo on the cabinet:

rivera07.jpg

 

And gone. Nice shot of the guts too:

rivera08.jpg

 

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.

rivera09.jpg

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That seems to have been a stellar era for Rivera. Back in '94, I recorded with a then-new Knucklehead and got some killer tones out of it. In fact, after tracking the same song with the same guitar/effects into a Marshall Jubilee 100w head and then, the Knucklehead, we decided that the track with the Rivera sounded better. I love Jubilees, so that's saying a lot for the Rivera.

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Oh wow. Jubilee Marshall's have always been one of those things I dreamed of. They still have a reissue they are putting out with small power output. Such a legendary design. I've always wondered why Marshall doesn't keep them in production continuously.

I have some more tubes coming today, so I may swap out the CBS-Hytron. I have found a lot about it, but mostly for Hi-Fi users. Some said it's too warm for Hi-Fi though. I could always spring for a used Mullard...

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It's always nice to see an amp that was obviously well taken care of go to another good home. Always thought those have a nice mix of features and they seem very well built.

How is the reverb in full on surf mode? I have had mixed results with reverb tanks that aren't in a bag so just curious.

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9 minutes ago, HAMERMAN said:

How is the reverb in full on surf mode? I have had mixed results with reverb tanks that aren't in a bag so just curious.

The reverb can get a bit "boinky", if you get what I mean. It's also got a bit of hum/noise, so I may swap out the tube to see if that makes it go away. It's nice though.

The best spring reverb I have in an amp is my Mesa Boogie Maverick. The tank is HUGE. Though the reverb on my Carvin MTS3212 is kinda boinky as well, and it's got a big tank and is tube driven. Then there's the reverb on my Mesa Boogie DC-5, which is great on the Clean channel, but nearly non existent on the overdrive channel. Apparently it was designed that way.

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Good score. I had an M100 2X12 that I got a smoking deal on and tried to use it for a couple of years but there were just too many knobs to tweak for a simple player like me so I sold it for a tidy profit. It was probably the sturdiest amp I have ever seen and sounded great in the right hands, just not mine. 

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7 minutes ago, shankyboy said:

Good score. I had an M100 2X12 that I got a smoking deal on and tried to use it for a couple of years but there were just too many knobs to tweak for a simple player like me so I sold it for a tidy profit. It was probably the sturdiest amp I have ever seen and sounded great in the right hands, just not mine. 

I still miss my M100 1x12. Got to hang out with Paul for about an hour playing with amp tones and settings, so the amount of options never bothered me after that, but I could see how it would just seem like too much to some people. That's what the other models were for though.

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18 minutes ago, Tortious said:

I still miss my M100 1x12. Got to hang out with Paul for about an hour playing with amp tones and settings, so the amount of options never bothered me after that, but I could see how it would just seem like too much to some people. That's what the other models were for though.

I was a beginner when I got that amp and had no idea what I was shooting for, tone-wise so having too many options was probably not a good idea for me at that time. :) 

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3 hours ago, shankyboy said:

Good score. I had an M100 2X12 that I got a smoking deal on and tried to use it for a couple of years but there were just too many knobs to tweak for a simple player like me so I sold it for a tidy profit. It was probably the sturdiest amp I have ever seen and sounded great in the right hands, just not mine. 

Oh wow.. I hadn't heard of that model before... holy crap every freakin knob has a pull something on it. TWO pull Gain switches on the "lead" channel, pull contour on the cleaner channel. And then there's the back of the amp.  That's some serious Mesa Boogie territory there, like a Rectifier or Mark V.

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1 hour ago, tbonesullivan said:

Oh wow.. I hadn't heard of that model before... holy crap every freakin knob has a pull something on it. TWO pull Gain switches on the "lead" channel, pull contour on the cleaner channel. And then there's the back of the amp.  That's some serious Mesa Boogie territory there, like a Rectifier or Mark V.

Yes indeed. That amp could peel the paint off the walls if you wanted to. 

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Congrats! I have never played a Rivera amp. They are scarce here in Scandinavia. I would really love to try one, one day.

I have the Rivera era Fender Deluxe Reverb II. It's a killer amp and tone machine and one I will never sell.

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2 hours ago, BubbaVO said:

Nice!   I like seeing how older gear in your hands always gets cleaned up and put in better shape than when you got it.  

How does the American channel compare with the "American" channel on the Maverick?

It's way more Fender sounding, even with the EL34 power tubes. In the regular configuration, it's very warm and chimey. The bright switch adds a good deal of shimmer to the sound, and it's just great. It has the notch switch, which takes it from "tweed" to "blackface", but I feel it sucks the life out of the channel. I guess it makes it more "clean", but I don't like it. It can get pretty dirty as well, but I think it sounds best clean and with a bit of breakup. It's gonna take some experimenting to really dial it in.

It's got a bit of noise from the preamp, which I tested by plugging something into the effects loop. I may swap the tubes back to stock, just so I can get a noise baseline. Also probably should clean the tube sockets and reverb connections, etc. Probably clean the pots too while I'm at it.

The UK Channel is definitely LOUDER than the U.S. channel. It's made to rock. It can get seriously nasty, though it does have a ton of mids, though they can be dialed out.

 

As for fixing things, I'm definitely OCD (diagnosed), so I just can't help it. I like things that are complete. My Marshall TSL122 just has original build quality issues that piss me off. When they put the rear baffles on, it's got some metal grills that go on as well. However, the wood they screw into is not plywood, it's just wood, and they used 3/16 diameter screws, which split the living hell out of the wood, as they didn't pre-drill anything. Most companies use wood or drywall screws, but they did not.

To fix that, I'm going to have to peel back the tolex, somehow fix the wood, reglue it, and then pre-drill some holes for the screws to go into.

I also now have a TON of 1/16 thick 3/8 wide foam, which I'm gonna be putting between all amp rear baffles. I looked at the Maverick last time I had the back off, and there actually was some kind of foam in there, but it's been totally squished, so I'll replace that as well. Some amps on the other hand, never had any thing to make a good solid connection between the rear baffle and the rest of the cabinet.

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Nice amp. Congrats!

Always loved any Rivera I came across, but i’m a muscle-less weakling and could barely lift em!

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10 hours ago, tbonesullivan said:

My Marshall TSL122 just has original build quality issues that piss me off. When they put the rear baffles on, it's got some metal grills that go on as well. However, the wood they screw into is not plywood, it's just wood, and they used 3/16 diameter screws, which split the living hell out of the wood, as they didn't pre-drill anything. Most companies use wood or drywall screws, but they did not.

To fix that, I'm going to have to peel back the tolex, somehow fix the wood, reglue it, and then pre-drill some holes for the screws to go into.

Dang, dude. Are you S&M, too? Just sell the damned thing and be free of the worry. 

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38 minutes ago, RobB said:

Dang, dude. Are you S&M, too? Just sell the damned thing and be free of the worry. 

It's been craigslisted for years. I couldn't get anyone local to buy it for $500, and shipping it would be insane. I think I may just be stuck with it.

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1 hour ago, Sugartune said:

Nice amp. Congrats!

Always loved any Rivera I came across, but i’m a muscle-less weakling and could barely lift em!

Really? This one honestly isn't that heavy, compared to other tube combos I have. Definitely lighter than the Mesa DC-5.

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