These mods are worth doing to any Signature/Bass-Master, IMO.
Sound Just like a plexi 50 watt Marshall (when used for guitar); Punk or loud rock (or with channel bridging Entwistle's bass sound) (when used for bass) Better sound as a Fender Bassman (bass and guitar); lower powered, would work just fine in a blues or lower volume setting (?
I caraked open the top on my 1975 YBA-1 just to look, and sure enough it's a 68K.
(Dave, Nov 11, 2014) - corrected version (Brian, Craig, Dan Lear, Dave Rutherford, DCloud1050, Eric Knudsen, Glen H., Greg, Jay Rogers, Jonathan Krogh, joth, Kraig Olmstead, Moon Keith, Ron Waters, Tim Casey, Tony Flagg, Vernon Fitch, viva Analog at bc.ca/~jc) Features Two channels (bass and guitar), two inputs for each channel, upper inputs are slightly attenuated; Treble and bass controls, a "tone expander" section with low and high knobs (according to Dan Torres, these are actually midrange and presence controls); there are two volume knobs that can be blended to get different sounds.
I have swapped out the 4M volume pots for 1M, and put a 47K resistor in the NFB loop. Professional repairman required, although schematic is included, weird defects possible. The YBA-1 serial number is 8011108 the YT-15 serial number is 7125596.
These mods are worth doing to any Signature/Bass-Master, IMO. CAD 3 used, bad price, amp in average (5/10) condition, Song Bird Music, Ottawa, Canada, summer 1998 US 5 [used], needed a little work but playable, cheap buy US 9.99 [used], seen at September 1998 CAD 9 [used], good condition, seen at Used Music, Ottawa, September 1998 CAD 0 [used], shabby condition, very early (pre October 1966) wrap-around type case model with tube rectifier, seen at Used Music, Ottawa, September 1998 CAD 5 [used], ca.
One [channel] sounds kind of like a "bright" channel and one sounds regular Two 6CA7/EL34 power tubes, three or four 12ax7s, solid state rectifier; hand wired, very high quality work, simple easy-to-modify circuit; larger [than the ones used in the Bass-Master YBA-1] 50-watt Hammond transformer (7 lbs.); Often operated with 4 ohm loads; best used with an eight ohms cab Runs on 540 volts, weights 54 pounds - bigger transformers [than the YBA-1] Dimensions: 8"x18"x10" (HWD); weight: 40 lbs.? (source: Catalog) Early [Bass-Master] Mark IIs have the (noisy) fan mounted on the end [in the cabinet side], later [Bass-Master] Mark IIs (with lift-off top, and the reflector 'Traynor' logo) have it mounted in the back [center]; Silvery grey grille cloth; Can exceed 600 volts on plate; expect about 550 volts, if you're lucky (one has eported 537 volts on plate) Early models are identical in appearance to the Voice Master/Signature.
If you are looking for something original sounding and with a good bit of style, this is it (if you can find one)!
Reliability It's a risky proposition for repairs Old and still going strong Price I bought my YBA-1A [used] about 15 years ago for USD.
[...] The 2nd [used] one I bought off ebay [for] 5 USD was totally moded for guitar with extra pots on the back [...].
[Oct 2002] US 0 used; one can be bought for under [US] 0 - a total bargain US 0 [used], needed a little work but playable, cheap buy US 9 used, you can get one cheaper CAD 0 [used], good condition, seen at Songbird Music, Ottawa, November 1998 (since January 1999 though, it had changed its condition to 'very good') Rating very good amp My personal opinion is that the YBA-1 is better for guitar, while the YBA-1A is preferable for bass.
My YBA-1A [...] uses 6550s and it's the best rock bass head that I've owned.