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Thread: FS: Radford ZD100 power amplifier, ‘Zero Distortion’ range, quite rare

  1. #1
    Join Date: Feb 2010

    Location: Berkshire, UK

    Posts: 1,881
    I'm Tom.

    Default FS: Radford ZD100 power amplifier, ‘Zero Distortion’ range, quite rare

    Been having quite a bit of fun with this, indeed it’s probably the best solid state amp I’ve ever heard in my system (and that includes a Krell KSA50). But now it's time to pass it on.

    Radford ZD100 power amp from the mid-70s, four mosfets per channel. The specs claim a truly astonishing 0.004% maximum total harmonic distortion at both 1khz and 10khz, qualified as ‘typically' 0.0015% which I suspect is barely within the limits of measurement. Intermodulation distortion less than 0.01%. The ‘zero distortion' tag comes from the fact that the entire range, power, pre and integrated, shows measured distortion below circuit noise level.

    Power is 90w into 8 ohms, 150w into 4 ohms. Input sensitivity is 1V so unless your sources are fairly high gain, it probably needs a preamp with some gain in it rather than a passive (it sounds very good indeed with the EAR 912).

    How does it sound? Well actually, quite a lot like a Radford valve amp. Natural rather than exaggerated or artificial highs, detailed but also punchy midrange, the biggest difference is in the bass quality which is stunning, in terms of both grip and depth.

    I really ought to keep it, but I have three power amps at the moment (Radford STA100, EAR 861 and this one) and I don’t really need three.

    Comes (amazingly) in its original 70s box (I have an outer box sorted for it to protect this)with both a printed multi-page data sheet and the technical instructions/installation and advanced maintenance booklet. Time-warp condition with barely a mark on it, and freshly serviced in February (including some parts replaced and rebiasing). There probably isn’t a better one out there.

    Probably suit a valve lover who needs more welly than valves can generally provide without getting all bulky and hot.

    I’m looking for Ł450 including courier for this, Ł425 if you can collect from Bracknell area. It's a crazy sonic bargain at that.

















    Last edited by montesquieu; 04-03-2017 at 20:28.
    Speakers - 'RFC' Tannoy Canterburys with custom crossovers; Amp - Radford STA100; Preamp - EAR 912; Vinyl: Thorens TD124 MkII with Ikeda IT345-CR1 and Ortofon 309 Limited tonearms; Cartridges: Miyajima Madake, Zero Mono 0.7 and Premium 1.0 retipped by Ana Mighty Sound with bamboo cantilever, Ortofon SPU Royal N and Shure M3D with Jico stylus; phono stage and SUT from EAR 912; Esoteric Sound Re-Equalizer for equalisation of early mono and 78; Digital: Audio Note CDT2/II transport.

    'Wer nicht liebt Wein, Weib und Gesang der ist ein Narr sein Leben lang.'

  2. #2
    Join Date: Feb 2013

    Location: W Lothian

    Posts: 35,470
    I'm Grant.

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    Lovely. I dont use a power and i still want it.... this shouldnt take long to walk.
    Regards,
    Grant ....

    I've said it before and I'll say it again: democracy simply-doesn't-work
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    DENON DV2900 - TWIN PRO MONOBLOCK AMPLIFIERS - XIANG SHENG DAC\PRE\HEADPHONE AMP - AUDIO TECHNICA ATH-MSR7 & OPPO PM-3 PLANAR HEADPHONES - WIN10 JRIVER23, SPOTIFY PREMIUM - SMSL M6 MINIDAC - FULL RANGE TWIN TELEFUNKEN's - Q ACOUSTIC BT3 actives - CANTON SUB - MAINS REGENERATED AND FILTERED.

  3. #3
    Join Date: Jan 2017

    Location: Kansas City, Missouri

    Posts: 590
    I'm Nathan.

    Default

    I want it, but I'm on the wrong side of the Atlantic.

    Sent from my Z981 using Tapatalk

  4. #4
    Join Date: Mar 2014

    Location: KY - Scotland

    Posts: 2,168
    I'm Mike.

    Default

    Any thoughts on how this would sound with a Croft Epoch?

    Visually it would match nicely but never having heard one I wouldn't have a clue if it's a good match sonically. My PMC 21's like a bit of power too so not sure if the 90w here will be more beneficial than the 72w from my TQ Claymore.

  5. #5
    Join Date: Feb 2010

    Location: Berkshire, UK

    Posts: 1,881
    I'm Tom.

    Default

    Should be a good match with the Croft.

    Haven't heard the Claymore so can't really comment on that. I suspect the design approaches are very different so you should hear a difference anyway!
    Speakers - 'RFC' Tannoy Canterburys with custom crossovers; Amp - Radford STA100; Preamp - EAR 912; Vinyl: Thorens TD124 MkII with Ikeda IT345-CR1 and Ortofon 309 Limited tonearms; Cartridges: Miyajima Madake, Zero Mono 0.7 and Premium 1.0 retipped by Ana Mighty Sound with bamboo cantilever, Ortofon SPU Royal N and Shure M3D with Jico stylus; phono stage and SUT from EAR 912; Esoteric Sound Re-Equalizer for equalisation of early mono and 78; Digital: Audio Note CDT2/II transport.

    'Wer nicht liebt Wein, Weib und Gesang der ist ein Narr sein Leben lang.'

  6. #6
    Join Date: Nov 2012

    Location: North Bham - West Mids

    Posts: 142
    I'm Manny.

    Default

    Have you mentioned this to Will at Radford Revival? I'm sure he'd be interested in this rarity.

  7. #7
    Join Date: May 2009

    Location: Wales, UK

    Posts: 221
    I'm Simon.

    Default

    Ooh...I'm tempted.
    Simon.

  8. #8
    Join Date: May 2012

    Location: Dagenham Essex

    Posts: 7,081
    I'm I'mteachingmarcotheartofpishanto.

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    Tom , any inside gubbins photos
    Music , fills the gaps between silence !

    TAT Sale post Leader " Marcos Mentor "

    Also a pishanto specialist confirmed by Head Daftee

    Real name " Allen " or "Zoomer Nut”, “Numpty Napper”.

    ±± KEEP IT REEL

  9. #9
    Join Date: Feb 2010

    Location: Berkshire, UK

    Posts: 1,881
    I'm Tom.

    Default

    Will see what I can do ... I generally leave the lids on because 1) all the fairy dust that makes them work might leak out, and 2) I'm a total klutz and might electrocute myself.
    Speakers - 'RFC' Tannoy Canterburys with custom crossovers; Amp - Radford STA100; Preamp - EAR 912; Vinyl: Thorens TD124 MkII with Ikeda IT345-CR1 and Ortofon 309 Limited tonearms; Cartridges: Miyajima Madake, Zero Mono 0.7 and Premium 1.0 retipped by Ana Mighty Sound with bamboo cantilever, Ortofon SPU Royal N and Shure M3D with Jico stylus; phono stage and SUT from EAR 912; Esoteric Sound Re-Equalizer for equalisation of early mono and 78; Digital: Audio Note CDT2/II transport.

    'Wer nicht liebt Wein, Weib und Gesang der ist ein Narr sein Leben lang.'

  10. #10
    Join Date: May 2012

    Location: Dagenham Essex

    Posts: 7,081
    I'm I'mteachingmarcotheartofpishanto.

    Default

    Quote Originally Posted by montesquieu View Post
    Will see what I can do ... I generally leave the lids on because 1) all the fairy dust that makes them work might leak out, and 2) I'm a total klutz and might electrocute myself.
    unplug it and keep body parts outside
    Music , fills the gaps between silence !

    TAT Sale post Leader " Marcos Mentor "

    Also a pishanto specialist confirmed by Head Daftee

    Real name " Allen " or "Zoomer Nut”, “Numpty Napper”.

    ±± KEEP IT REEL

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