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Hiwatt preamp questions - DIY

Discussion in 'Amps and Cabs [BG]' started by Matt B, Mar 1, 2016.


  1. Matt B

    Matt B

    Mar 31, 2012
    New Zealand
    Hey Guys,

    Looking for some advice from someone with some hiwatt experience...

    I am part way through building a DR201 (almost) clone and i am hung up on the best pre-amp variation to run with and need to decide in the coming days. There are subtle differences between the schematics and I read about preferred options being the older kind, some of the 60s and 70s options do not use all the triodes available so it would leave me a spare one for adding a DI down the track.

    The Schematics i have are
    >early 80 DR405 - this is what i was favouring initally. the bright and normal channels each have a dedicated triode after the initial gain stage as opposed to the older ones which do not use one (which is where the spare triode comes from)

    >and a 70s one that is very similar apart from the above mentioned gain stage and some filtering that i may play with anyway... Then reading on the internet (so was certianly true) is that there was something lost in the 80's and the 60s and 70 preamps were preferred. (or was this for getards only)

    so what do you all think? 70's version and have a triode up my sleeve or 80s and use that extra gain stage...

    thanks,
    Matt
     
    Last edited: Mar 1, 2016
  2. Matt B

    Matt B

    Mar 31, 2012
    New Zealand
    ??
     
  3. bb5000

    bb5000

    May 30, 2006
    Sundsvall, Sweden
    I use a mix of the DR405 and late 70s preamp in my DR201 build and it still sounds like a Hiwatt with guitar: The Normal channel has a 25 uF cathode bypass cap in V1, Brilliant channel has a 1 uF cathode bypass cap. The coupling cap after V1 for the Brilliant channel is 10n. On to V2, it's wired like the DR405, so both triodes are used...the rest of the preamp is stock Mid-70s without the optional 47n cathode cap on V3a.
     
    bgmww likes this.

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