If It’s Valves You’ve Come For…

6 08 2008

The 6BQ5, also known by it’s European designation of EL-84, is renowned as one of the most prized tubes among amp designers and it’s characteristically sweet tone is the foundation of the Skylark’s sound. The other valves in this amp aren’t so familiar. The 6EU7, which Gibson used a fair bit in different 1960’s tube amps, is a low noise alternative to the more commonplace 12AX7 but the two preamp valves are of equal gain values and overall are ,very similar. The 6C4 tube was used in many applications, such as organs, ham radios and even TVs but Gibson used them in amps as either rectifiers or in this case, a phase inverter.


It’s All About The Glass

5 08 2008

As can be seen here with the photo turned upside down, there are four tubes in the Skylark; a pair of 6BQ5, a 6C4 and a 6EU7. Going from left to right, the 6EU7 serves as the power tube and its faint red RCA marking is barely legible. Next is the phase inverter, a 6C4 bearing the yellow script “made in USA for Ampeg by Sylvania 939 JFO”. The first 6BQ5 in the lineup sports the “RCA electron tube” marking while its partner 6BQ5 makes do with “RCA USA”. The tubes are old but after warming up a bit, still kick out a toneful 4 or 5 watts.

A Peek Under The Skirt

4 08 2008










The Skylark is a pretty clean machine under the bonnet; four tubes, three pieces of iron, an old tremelo switch footpedal and big ol’ 10 inch generic speaker. The power transformer is a bit rusty but looks original? Stamped on it is the sequence “TF-105-P 9966606”. The output transformer bears “TF-504-0 549-6538” while the choke is branded “TF-1001 D 757 6549”.  The underside of the chassis has “insp by 152246” printed on it with the “15” being larger than the following numbers.

Opening Up The Beast

28 05 2008

Taking the old starpoint to the Gibson GA-5T yields a glorious bit of information as soon as the speaker cavity guard is removed. On the back of the guard, a faded white sticker displays the following information: “Don Randall Music 6/8/67”.  A bit of research turns up that Don Randall Music was a big music store located in downtown Lancaster, Pennsylvania from 1963 to 2001 when it was sold by Don Randall’s widow to the retail chain “Music & Arts Center”. 

Back In Black

12 05 2008


Full Throttle

31 03 2008

1965-66 Gibson GA-5T Skylark 25

Peaking the volume on the Skylark brings out a tiger! It finally gets nice and loud enough to bother someone on a different floor in a house and on chords, it’s all claws and spite. On a G&L Skyhawk, open string power chords can pass off a fair Bon Scott era AC DC imitation while higher up the neck, sharp, clipped minor chords bring to mind a “London Calling” feel. As with lower volume work, single note leads don’t breath the same fire but a light touch elicits a wee bit of “Little Wing” Fender Black Face snappyness while really digging in draws up some of Stevie Ray’s cleaner lead work.

The Sweet Spot

23 03 2008


Moving the loudness nob up to 75% brings a big jump up in volume and single notes are definitely getting juicy. Hard strummed chords bring out the moderate distortion generated by the Skylark and it reminds me of Paul McCartney’s rhythm sound from the guitar parts he played on some mid-sixties Beatles albums.  Not a hard rock sound but forceful enough with it’s wide touch sensitivity to bring out a wonderful range of tones.