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
Customers Vibroclones
Vibroclone Cost Estimate
For my latest Vibroclone builds, please visit my Facebook page and click on photos.
