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Thread: History of the vht ul

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    Default History of the vht ul

    Props to NoGodsNoMasters for this info:

    The "One Hundred" was the predecessor of the UL. Basically configured from the pre of the Classic head, 3 channels, and one output side of the 2150, thus two power tubes, using an output transformer from a 2150.

    Tube config was:

    Preamp, 1 Sovtek 12AX7WB, 3 Chinese 12AX7A.
    Power amp, 1 Chinese 12AX7A, 1 Chinese 12AU7.
    Power tubes: 98 wattss

    Svetlana began having troubles and we only had Chinese KT88 to fall back on which didn't hold up well so we went to 4 power tubes and a modified output transformer to run 4 tubes.

    This wasn't intended to be a massive gain amp, although a lot by the standards of the time. As things progressed we responded to requests for more gain and power amp saturation. We tried making the driver tube (12AU7) interchangeable to help tweak power amp distortion, but ultimately it created as many problems as it solved so that idea was scrapped in favor of a softer sounding driver stage. The new tube config was:

    Preamp, 1 Sovtek 12AX7WB, 3 Chinese 12AX7A.
    Power amp, 1 Chinese 12AX7A,
    Power Tubes: 4 Chinese KT88.
    Output power: 105 watts.

    This was met by our beloved clan with either great enthusiasm or extreme anger. If you were in a band and wanted one just like the other guitarists, you either appreciated the difference and it worked well for the overall sound of the band, or you were pissed because yours was not as aggressive.

    After a year of this, the UL went back to tow tubes in the drive/phase inverter stage, but with a difference. A new driver design using a 12AT7 in place of the 12AU7 for the driver. The idea being to restore the tightness and aggressive UL trademark but retain some of the fatness of the 12AX7 only style. By then the Sovtek KT88 became available and that became what is still the standard tube for the UL: New Tube config:

    Preamp, 1 Sovtek 12AX7WB, 3 Chinese 12AX7A.
    Power amp, 1 Chinese 12AX7A, 1 Chinese 12AT7.
    Power Tubes: 4 Sovtek KT88.
    Output power: 120 watts.

    For those who liked the softer more saturated power amp quality of the 5 tube UL and wanted even more, the Classic head was redesigned using the 5 tube preamp config and renamed the CLX at the request of Mr. Hartley Peavey who owns the trademark for the use of Classic on guitar amplifiers. New CLX tube config:

    Preamp, 1 Sovtek 12AX7WB, 3 Chinese 12AX7A.
    Power amp, 1 Chinese 12AX7A
    Power Tubes: 4 Svetlana EL34s.
    Output power: 110 watts

    Keep in mind that at the time all of this was going on, tube supplies were very erratic and unstable. The Tesla factory got bombed, or so they say, new 6550 designs were all over place in terms of quality and reliability, and we were constantly having to shift gears in order to maintain a performance level that depnded ontop quality tubes.

    Obviously the tube scene has settled down and has been stable for quite a while now. As a result, there have been no major changes in the UL or CLX power plants since mid 97.
    Last edited by support; 03-17-2011 at 06:53 PM.
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