The Super Reverb project is finished...three years later...

[212Mavguy]

A few years ago I came into possession of a '68 blackline silverface Super Reverb in non-op condition, passing no signal and two blown speakers for 350 bucks. Over a period of time and with help, I did and had some stuff done to it.

 

There was a bit of crackling in the sound when I was able to get it up and running. So all the resistors were replaced with new CC ones, blueprinted tightly to stock values, no more crackle. New filter caps and cathode bypass caps went in, and in the trem channel the blue molded caps went away to my "saved parts" bag and were replaced by vintage German and Russian military paper in oil ones. Yep, an abomination...it's my amp, so suck eggs if you don't like the thought. Bias meter jacks were installed. The further abomination of drilling holes in a vintage chassis ended with a barely visible result hidden within the printing on the black back faceplate... Hey, this was a POS anyway, not a museum piece.

 

The speakers were not top end when new, and the cost of shipping and reconing four mediocre CTS 10's was not appealing. So I got a 1/15 baffle from eBay, sourced a NOS, unplayed Altec 418H series II speaker, ordered up a 60w non-m6 OT from Classic Tone with 2/4/8 secondaries to replace the stock two ohm unit.

 

Then it went to my tech for conversion to bias modulated tremolo, where it sat for over a year. I did not rush him, was necessary for him to do some research on that mod, and he was always really busy anyway.

 

I got a call and brought it home today. I was stunned it sounded so sweet. More headroom, waaay better sustain than stock, and the tremolo, it sweetly gushed out with no chop to it. The cleans were the BIG Fender amp sound, all but forgotten, full yet sweet, no muss on the pixie dust on the top end. That big Altec handled low notes and pig squealin' pinch harmonics at the same time flawlessly. The voices of the clean tones through this speaker were sweeter and more detailed soft or loud than even my other 15 faves, JBL's relatively unknown MI-15 and G135-8...in this particular circuit. Yes, I rolled vintage speakers besides vintage tubes for this amp, too.

 

It was possible to dial in a trem setting where the note or chord would sustain for two or three whole notes, then the throbbing would gradually start in the decay, harmonics gushing out, note flipping like a Dumble in prolonged sustain at higher volumes, or raise intensity to have tremolo going nearly all the time as well. What I was not prepared for was the incredibly sweet grind when the volume was cranked up over 4, into OD...or the never ending, controllable sustain with it. Having an active pedal steel volume pedal like a Hilton is a lot of fun in front of this amp, it also handles multi effects pedals like my TC Nova very well. I'm not ever going to bring it back stock, it's too good now. So if you have access to a decent early SR or showman this mod set is a PITA for a tech to dial in but is worth it sonically. My guy only wanted to charge me 50 bucks because it took so long, I replied that it took a lot of head scratching and subbing out components on his time's dime to get the desired result, lots of PITA trial and error, so I made him take 150 bucks so that he'd be not scowling when I bring in my next unusual project...This is the usual way I deal with him. He always undercharges me. Nowadays unless it's a toughie I do my own work anyway. The tones are priceless.

 

I don't do clips or pics...so don't shoot me please.

[DetroitBlues]

Good deal... Seems like it was worth the wait.

[tbonesullivan]

Sounds like a great project! Glad you are pleased with the results.

[FredZepp]

That sounds amazing. The post is a good read ... with all the details and results.

 

And you pre-empted my forthcoming request for pics... ha..

 

Your description of the tremolo starting in the decay sounds like heaven.

 

And that mighty, thundering Altec... good stuff , indeed.

[tbonesullivan]

Until this thread, I wasn't really aware there was more than one way to do tube tremolo. Of course, youtube has a video comparing the bias method with the LDR/Opto version:

 

 

 

Not really sure I am nuanced enough to really tell the difference.

[212Mavguy]

This video displays a clear difference even though it was recorded in a way not well designed orset up to display differences between the two types.

 

Even so, the recorded sample displays that the way the sound reduces and returns in volume with the LDR is choppier, more abrupt sounding in sound and waveform. And this was only with the clean tones at a volume where the power sections of either amp really aren't working much.

 

With longer sustain and especially with wattage pushed at higher levels than what was displayed the harmonic character of the decay becomes more different between the two types with the increase of decay time due to the output tubes' screen grids being starved for electrons in the quieter sounding part of the bias wiggle waveform. As the result of that starvation, harmonics are introduced, repeated, and become further sustained during the louder sounding part from the power tubes themselves during the process. I have three amps with bias trem and one '81 Super Reverb with LDR, the bias setup Super Reverb is much sweeter sounding in a mix as well as alone than the LDR clean or dirty, this particular LDR equipped Super came wih the orange frame JBL D110's in it...