Vibroclone (a.k.a. 1965 Blackface Vibroverb "Clone")

Original '64 Vibroverb

This project started from the inspiration of early Stevie Ray Vaughan, (see Mocambo video) using 1964-65 Blackface Vibroverbs and having worked on several originals. First two I worked on had an original Jensen C15N. The C15N just can't handle the power of the verb and tends to "fart" out when cranked. Third Vibroverb in for work had the JBL D130F option, and I was hooked. Had to have one. Have to have a small fortune too. In conversations on the Internet in early '95 concerning Fender amps with John Stokes, he used the phrase "bass for days" when referring to the tone of a 15" speaker. John had just completed his Vibroverb knock-off. Now it was my turn. Chassis is a '72 Bandmaster Reverb (BMR). Speaker is a reconed JBL D130. A complete electrical restoration was performed on the chassis along with a Blackface conversion. All wires were trimmed for excess length. I spent a lot of time voicing the amp to match its new environment. Not satisfied with the farty bass and remembering the three originals I worked on all needed more bass response headroom, I began experimenting with transformer impedance mismatch. Realizing all the time the stock BMR output transformer (OT) and the original Vibroverb OT are wimpy, I installed a used '67 Twin Reverb OT knowing the turns ratio with only two output tubes and a 8ohm load would be a perfect match but with more transformer iron. A slight tone cap adjustment and bingo, excellent clarity with a hint of breakup with really tight bass. Yes, "bass for days". Final voicing included using NOS Philips 7581A's and NOS GE preamp tubes. With the JBL and Twin Reverb OT, I opted for a NOS 5U4GB instead of a 5AR4 for a little more compression. Converted to dual channel reverb, with the normal channel gained up a little. The Vibrato bass and mid caps were changed to 0.033uf. Stock tone caps, were too tinny and two 0.022uf caps were too bassy. Output tube bias is set a little hot at 38ma/tube.

Why "Vibroclone"? During email conversations with a work-related buddy and another serious tube enthusiast, I was talking about my latest project I referred to as a Vibroverb clone, as in IBM PC "Clone". After several days of conversation regarding this project, Grego shorten it to Vibroclone. One word, less to type, gotta be a good thang!


Start with a Gregg Hopkins blank finger joint cab, rebuilt Bandmaster Reverb Chassis and a JBL D130F.
This pic was taken before a TR OT was installed. Note gray AC power cord for Verb authenticity.
Cabinet plans Link
Center Mounted JBL D-130 Link


 



Add back panels, sound board, tolex and hardware.           Don't forget a new tube chart.



Lean it back and have some tone to the bone!


Vibroclone with restored '68 Twin Reverb.

 

More Vibroclone Information
BMR history and more Vibroclone design details
My latest Vibroclones
Vibroclone Cost Estimate

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