R200

Tubes:

  • R200: 2-12J5; 1-50L6; 1-35Z5
  • R200B:  2-12BF6, 1-50L6, 1-35Z5

Speaker: 1-8″

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Click to enlarge:

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Lectrolab R200 =2-12J5; 1-50L6; 1-35Z5

  • 2 Inputs, one Volume, one Tone control.
  • The filaments in these tubes are powered by  25 to 50 volts AC.  This is in contrast to almost all modern amps which use 6.3 volts.
  • 50L6 is the power amp tube, capable of 4 to 8 watts depending on the circuit.  Without knowing the transformer specs, or measuring an example, we can’t state with certainty what the R200 output is.
  • 35Z5 is the rectifier.  These have been used in other designs with no power transformer, which can lead to the chassis being “hot” (117VAC) whether the amp is on or off.  I believe the term “widow-maker” refers to that design feature. The R200 and R200b schematics both show a power transformer that would isolate the line voltage from everything but the  tube filaments.  One side of the AC line is tied to ground through a capacitor, creating a “signal ground”.
  • This does not make them safe!  The schematic does not show how the chassis is grounded.

Lectrolab R200B = 2-12BF6, 1-50L6, 1-35X5

  • 3 Inputs, one Volume, one Tone control.
  • Odd choice of tubes for the preamp.  12BF6 contains “two diodes and a medium-mu triode in one envelope” (from the 1952 RCA Datasheet at http://www.shinjo.info/frank/sheets/079/1/12BF6.pdf).  Your standard 12AX7 has two high-mu (read high gain) triodes.  The diodes in the 12BF6 in the R200B are grounded, unused.  Like the R200, the “B” uses two preamp tubes with one triode each, requiring two tubes where one 12A_7 would do the trick.

Note that the Lectrolab R204D is a completely different amp.  Not that you would be likely to wonder about that, since only one is now known to exist.  See the page devoted to that at https://lectrolab.wordpress.com/lectrolab-models/r204d/

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This sound clip runs a Lectrolab R200B up against some serious competition.  Friends, this little puppy stands tall at the end of the fray!  If you are a recording guitar player then run, don’t walk, to the nearest sale of this inexpensive Fender Killer.

http://media.zvex.com/sounds/box_of_rock_demo.mp3

Notes on the clip from the Zvex website:

Every guitar you hear went through the Box Of Rock. All the rhythm tracks are vintage 1971? Marshall Super Lead (modded by Andy Wolf) through an old greenback Marshall 4X12, the various amounts of gain, from light clipping to crunch are settings, came from the pedal.

The first solo was a Lectrolab R200B, it’s a little class “A” Champ kind of thing, with a 6 inch Jensen. Volume and tone were cranked. The second solo was a “transitional” Silver Faced Fender Pro Reverb at about 3 1/2, bright switch on, treble? at 7, bass on 3. The last solo was a Brown Fender Princeton. The amp was set at about 4 1/2, with the tone on about 5 1/2.

Everything was a 57 up close. I used a multiband compressor to remove some “woof” from the 4X12 during mixdown, a touch of compression over the final mix, and that was it. The whole thing was a Don Grosh Strat with Lindy Fralin pickups, strung up with GHS 12’s.

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Here’s another sound clip from a forum called thegearpage.net.  The author says: “It has a real warm sound to it. Both knobs are on 10, so it’s already starting to overdrive. Then you’ll hear me roll on the EMG Afterburner at about 22 seconds.”

 R200 from the gear page

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Lectrolab R200B – Nasty distortion:

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Sound Projects Co. (Lectrolab) R200B – Do you really want to play bass through this?

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Lectrolab R200 from 1953?  This is what the author claims in the video, but I have not seen another example of this particular amp, nor can I make out any markings on the chassis in the video.  Could this actually be the elusive Lectrolab R100?





3 Responses to R200

  1. randal panter says:

    does anyone know the part number for the out put transformer for the r200b amplifier? I’m trying to get this working and it has a constant hum that is un affected by the volume control. I’m only reading 1 ohm on the output wires of the transformer.can anyone help. mine only has two input jacks.

  2. Clyde says:

    I have an r200b from 1957 that did the same thing. it turned out to be a bad multi-section filter cap.

  3. Mike Jobe says:

    I think you have other problems other than a output transformer, which I dont think is bad.

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