Is the Gibson Skylark a fixed or cathode biased amp?

bloc · July 6th, 2003, 04:39 AM

I have a mid 60's model Gibson Skylark (GA-5) that has one 12AU7 and two 6BQ5 (EL84's). Could anyone say if the amp is a fixed or cathode biased amp? Thanks in advance.

Marky D. · July 6th, 2003, 12:52 PM

My guess is that it's fixed bias w/ the power tubes in a push-pull configuration. I have the chassis for one of these and I'm looking for the cabinet dimensions and a schematic if anyone has one.

I had one of these in the 70's and ran it w/ all knobs on 10 into a 1-12" Altec. With a Les Paul and a booster in front, it was a screamer!

Silverface · July 6th, 2003, 01:19 PM

From what I recall of the one I had it's cathode-biased.

BTW - the power tubes in mine were not 6BQ5's - they were 6AQ5's!

willie · July 6th, 2003, 01:46 PM

From what I can recall...there are actually three or four versions of the GA-5 Skylark...one that uses a single ended 6V6, one that uses a single ended 6BQ5, and one with a single 6AQ5...there is also a rare one that used two 6BQ5s in push pull. All but the later were self biasing...but this is pretty much from memory.

Wally · July 8th, 2003, 12:48 PM

I would wager that it is a cathode-biased amp. The schematic for the GA-5 Crest, which runs two 6AQ5 power tubes, is a cathode-biased arrangement.
Has anyone ever noticed how similar some of the Gibson/Epi amps sound compared to the Vox? I have read that Jennings and or the other Vox designer (can't recall his name) utilized the tone circuit from a Gibson amp. I do know that with a Alnico Celestion from the '60's, my Epi with 2 6BQ5's does that 'Vox' chime better than any other amp other than a Vox....maybe as well.

TNO · July 11th, 2003, 11:21 PM

The american Voxes and the post-'61 Gibbies were both made by Thomas Organ.

TNO · July 11th, 2003, 11:23 PM

The american Voxes and the post-'61 Gibbies were both made by Thomas Organ.

Wally · July 12th, 2003, 03:52 PM

TNO, I find that info about the Thomas Organ Co. interesting. Where did you get that info? You are the first one that I have come across that has had any idea where the later Gibsons were made. I have had a DeArmond amp that so closely resembled the early '60's Gibsons with the rear facing controls that I wondered if Rowe Ind didn't make the Gibson/Epi products in their factory.
Any revelatory info to which you could direct me would be of great help. I do believe that the refence that I was making would have involved earlier Gibson schematics, but I sure would like to learn anything at all about Gibson amp manufacturing...who, where, etc.

SBD · April 11th, 2005, 08:19 AM

http://www.informatik.uni-bremen.de/~dace/gg/amps.html

Chris S. · April 11th, 2005, 11:04 AM

Quote:

Originally Posted by SBD

http://www.informatik.uni-bremen.de/~dace/gg/amps.html

Great link, thanks for digging the thread out of the basement. ;-) CS

SBD · April 11th, 2005, 12:12 PM

NP, it´s pretty useable :)

July 6th, 2003, 04:39 AM	#1 (permalink)
bloc NEW MEMBER! Join Date: Apr 2003 Posts: 2	Is the Gibson Skylark a fixed or cathode biased amp? I have a mid 60's model Gibson Skylark (GA-5) that has one 12AU7 and two 6BQ5 (EL84's). Could anyone say if the amp is a fixed or cathode biased amp? Thanks in advance.

July 6th, 2003, 12:52 PM	#2 (permalink)
Marky D. Tele-Meister Join Date: Mar 2003 Location: Minneapolis, MN Age: 47 Posts: 314	Skylark My guess is that it's fixed bias w/ the power tubes in a push-pull configuration. I have the chassis for one of these and I'm looking for the cabinet dimensions and a schematic if anyone has one. I had one of these in the 70's and ran it w/ all knobs on 10 into a 1-12" Altec. With a Les Paul and a booster in front, it was a screamer!

July 6th, 2003, 01:19 PM	#3 (permalink)
Silverface Tele-Afflicted Join Date: Mar 2003 Location: Hermosa Beach CA Age: 56 Posts: 1,934	Skylark... From what I recall of the one I had it's cathode-biased. BTW - the power tubes in mine were not 6BQ5's - they were 6AQ5's! __________________ “No Chops – Great Tone” ©

July 6th, 2003, 01:46 PM	#4 (permalink)
willie TDPRI Member Join Date: Jun 2003 Location: Dixie Posts: 30	Ga-5's... From what I can recall...there are actually three or four versions of the GA-5 Skylark...one that uses a single ended 6V6, one that uses a single ended 6BQ5, and one with a single 6AQ5...there is also a rare one that used two 6BQ5s in push pull. All but the later were self biasing...but this is pretty much from memory.

July 8th, 2003, 12:48 PM	#5 (permalink)
Wally Friend of Leo's Join Date: Mar 2003 Location: Lubbock, TX Posts: 4,212	I would wager that it is a cathode-biased amp. The schematic for the GA-5 Crest, which runs two 6AQ5 power tubes, is a cathode-biased arrangement. Has anyone ever noticed how similar some of the Gibson/Epi amps sound compared to the Vox? I have read that Jennings and or the other Vox designer (can't recall his name) utilized the tone circuit from a Gibson amp. I do know that with a Alnico Celestion from the '60's, my Epi with 2 6BQ5's does that 'Vox' chime better than any other amp other than a Vox....maybe as well.

July 11th, 2003, 11:21 PM	#6 (permalink)
TNO Tele-Meister Join Date: Apr 2003 Posts: 220	The american Voxes and the post-'61 Gibbies were both made by Thomas Organ.

July 11th, 2003, 11:23 PM	#7 (permalink)
TNO Tele-Meister Join Date: Apr 2003 Posts: 220	The american Voxes and the post-'61 Gibbies were both made by Thomas Organ.

July 12th, 2003, 03:52 PM	#8 (permalink)
Wally Friend of Leo's Join Date: Mar 2003 Location: Lubbock, TX Posts: 4,212	TNO, I find that info about the Thomas Organ Co. interesting. Where did you get that info? You are the first one that I have come across that has had any idea where the later Gibsons were made. I have had a DeArmond amp that so closely resembled the early '60's Gibsons with the rear facing controls that I wondered if Rowe Ind didn't make the Gibson/Epi products in their factory. Any revelatory info to which you could direct me would be of great help. I do believe that the refence that I was making would have involved earlier Gibson schematics, but I sure would like to learn anything at all about Gibson amp manufacturing...who, where, etc.

April 11th, 2005, 08:19 AM	#9 (permalink)
SBD TDPRI Member Join Date: Feb 2004 Location: Sweden Posts: 39 33 Photos	http://www.informatik.uni-bremen.de/~dace/gg/amps.html

April 11th, 2005, 12:12 PM	#11 (permalink)
SBD TDPRI Member Join Date: Feb 2004 Location: Sweden Posts: 39 33 Photos	NP, it´s pretty useable :)