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Thread: The Croft Epoch - A Tale of developing a MoFo of a pre amp..........

  1. #21
    Join Date: Nov 2010

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    I'm AnDreW.

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    DSCN2027.jpgDSCN2028.jpgDSCN2032.jpgDSCN2033.jpg

    Some pics of the innards of the Epoch. Pretty standard stuff. This example has x5 6H9C instead of x5 6SL7, x1 6GV8 instead of a ECC83 and x1 85A2. I'd be interested in finding out why I have the 6Gv8 instead of the ECC83
    SS CD Teac VRDS25X(Mega Modded) DAC Caiman SEG+Anker PSU DECK 1210 Mat Analog Studio Crystal Mods MN Base/Bearing/Platter+Ebony arm Board Feet Isonoe PSU Paul Hynes SR7EHD-27XL/DCSXL Ag DC lead/Jaeger(low-impedance) connector/3 StageRegs/Recapped PCB+No Pitch/Strobe/Light ARM SME V(Kondo Ag Rewire&Tags) MC Cadenza Black CABLES Arm Yannis SPD-4 IC Yannis 222 Litz+Ag bullets Power WAR PRE ATC SCA2 SPEAKERS ATC 50ASL STANDS Atacama PHONO Sugden Masterclass PA4 SUT Ortofon ST80SE POWER PSAudio P10

    Valve PRECroft Epoch(Mega Modded) AMP Sondex S100 SPEAKERS Tannoy 15"MG+RFC Warwick cabs+ Reference XO DECK Garrard301 MatTeunto GunMetal Bearing SPH Plinth Moldovan Arm SME 3012(Ikeda Ag wired) PSU NSC MCAg Meister SPU/DECCA Maroon CABLES Arm Yannis 420.5 Litz+ Speaker3mm2Ag IC Oyaide FTVS-510 AgWBT 0110Ag Phonostage Paradise


  2. #22
    Join Date: Oct 2012

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    I'm Alan.

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    Quote Originally Posted by REXTON View Post
    Usually a big glug of single malt Brian! I hope you enjoy the thread and I'll be posting some pictures later.



    Thanks!

    Well I got another email and the fully monty includes :-

    Seiden selector switch.____________\
    Eichmann phono sockets.__________\
    Khozmo attenuator._______________\ All good quality stuff Andrew
    SCR Teflon output caps.___________/
    Rike PIO coupling caps.___________/
    Clarity Cap TC4 power supply caps. /
    Separate transformer box with separate 500VA transformers for each channel.
    Separate hybrid ht supplies for each channel.

    Individual heater regulators for each valve.

    Additionally I have no idea what " Individual heater regulators for each valve" are and God only know's what "Separate hybrid ht supplies for each channel." can be .
    The separate transformers feeding separate ht supplies is the best approach for minimum crosstalk between channels. The 'Separate hybrid ht supplies' just means that valves and FETs are being used in the power supplies to give maximum performance.

    Individual heater regulators are very easy to implement, just a 3 terminal regulator chip, also I imaging to ensure no crosstalk between different stages.

    Very similar approaches that I incorporate in my designs.
    Firebottle - for the no bottleneck approach.

    I love Hendrix for so many reasons. He was so much more than just a blues guitarist - he played damn well any kind of guitar he wanted. In fact I'm not sure if he even played the guitar - he played music. - Stevie Ray Vaughan

  3. #23
    Join Date: Nov 2010

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    Quote Originally Posted by Firebottle View Post
    The separate transformers feeding separate ht supplies is the best approach for minimum crosstalk between channels. The 'Separate hybrid ht supplies' just means that valves and FETs are being used in the power supplies to give maximum performance.

    Individual heater regulators are very easy to implement, just a 3 terminal regulator chip, also I imaging to ensure no crosstalk between different stages.

    Very similar approaches that I incorporate in my designs.
    Alan, many thanks for the reply. I've bought a couple of simple electronics books so that I have some grasp of what I'm talking about. I need to re-read the passive amp thread of Marcos with regarded attenuators but I think the basic principles of these are quite simple to understand. I just need to get my head around FETs and how they work with a valve to regulate the power. I understand what "cross talk" so I can see why some of the components are being used. Looks like I need to do some reading around heater regulators, maybe tonight's homework?!
    SS CD Teac VRDS25X(Mega Modded) DAC Caiman SEG+Anker PSU DECK 1210 Mat Analog Studio Crystal Mods MN Base/Bearing/Platter+Ebony arm Board Feet Isonoe PSU Paul Hynes SR7EHD-27XL/DCSXL Ag DC lead/Jaeger(low-impedance) connector/3 StageRegs/Recapped PCB+No Pitch/Strobe/Light ARM SME V(Kondo Ag Rewire&Tags) MC Cadenza Black CABLES Arm Yannis SPD-4 IC Yannis 222 Litz+Ag bullets Power WAR PRE ATC SCA2 SPEAKERS ATC 50ASL STANDS Atacama PHONO Sugden Masterclass PA4 SUT Ortofon ST80SE POWER PSAudio P10

    Valve PRECroft Epoch(Mega Modded) AMP Sondex S100 SPEAKERS Tannoy 15"MG+RFC Warwick cabs+ Reference XO DECK Garrard301 MatTeunto GunMetal Bearing SPH Plinth Moldovan Arm SME 3012(Ikeda Ag wired) PSU NSC MCAg Meister SPU/DECCA Maroon CABLES Arm Yannis 420.5 Litz+ Speaker3mm2Ag IC Oyaide FTVS-510 AgWBT 0110Ag Phonostage Paradise


  4. #24
    Join Date: Jan 2009

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    I'm Mark.

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    Now this is a lot of Croft pre-amp:


    100% Analogue

  5. #25
    Join Date: Oct 2012

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    I'm Alan.

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    Going the hybrid route and using FETs, particularly in the power supply circuitry, is a designers wet dream.

    Put simply the characteristics of power FETs is like a valve on steroids, so you get whatever benefits accrue from using valves but with much better performance, there is also the simplification of no heater required.

    The individual heater regulators are a bit OTT possibly, as I wouldn't expect any crosstalk between stages via the individual heaters. However it does make any fault protection or fault finding that much easier.


  6. #26
    Join Date: Nov 2010

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    Quote Originally Posted by YNWaN View Post
    Now this is a lot of Croft pre-amp:

    That indeed is one hell of a preamp, probably cost one hell of a lot of money as well.

    Quote Originally Posted by Firebottle View Post
    Going the hybrid route and using FETs, particularly in the power supply circuitry, is a designers wet dream.

    Put simply the characteristics of power FETs is like a valve on steroids, so you get whatever benefits accrue from using valves but with much better performance, there is also the simplification of no heater required.

    The individual heater regulators are a bit OTT possibly, as I wouldn't expect any crosstalk between stages via the individual heaters. However it does make any fault protection or fault finding that much easier.

    Thanks that goes some way to explaining why Glenn selects the things he does.
    Last edited by REXTON; 24-11-2015 at 20:02.
    SS CD Teac VRDS25X(Mega Modded) DAC Caiman SEG+Anker PSU DECK 1210 Mat Analog Studio Crystal Mods MN Base/Bearing/Platter+Ebony arm Board Feet Isonoe PSU Paul Hynes SR7EHD-27XL/DCSXL Ag DC lead/Jaeger(low-impedance) connector/3 StageRegs/Recapped PCB+No Pitch/Strobe/Light ARM SME V(Kondo Ag Rewire&Tags) MC Cadenza Black CABLES Arm Yannis SPD-4 IC Yannis 222 Litz+Ag bullets Power WAR PRE ATC SCA2 SPEAKERS ATC 50ASL STANDS Atacama PHONO Sugden Masterclass PA4 SUT Ortofon ST80SE POWER PSAudio P10

    Valve PRECroft Epoch(Mega Modded) AMP Sondex S100 SPEAKERS Tannoy 15"MG+RFC Warwick cabs+ Reference XO DECK Garrard301 MatTeunto GunMetal Bearing SPH Plinth Moldovan Arm SME 3012(Ikeda Ag wired) PSU NSC MCAg Meister SPU/DECCA Maroon CABLES Arm Yannis 420.5 Litz+ Speaker3mm2Ag IC Oyaide FTVS-510 AgWBT 0110Ag Phonostage Paradise


  7. #27
    Join Date: Nov 2010

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    So tonight has been spent looking at what I don't need inside the amp and looking at areas which can be left alone. For example, do I really need to spend time and money on the Tape Input/Output RCA, do I need regulation for these areas,why should I need to buy a valve when I've no intention of using this option on the amp? Litttle things like these have been running through my mind. So I'm thinking the Phono In/Out, Line 1, and Main in/out could do with some magic, the others can just sit there for all I care in fact it would be nice to have an option to bypass them, remove them and then simplfy the circuit. More questions for Glenn! The transformer sitting in the corner also looks useful, could this be used for further power regulation in some other area of the amp's design? I'm also thinking that if I'm going to be using Charcroft resistors in the attenuator why not through the whole amp?
    SS CD Teac VRDS25X(Mega Modded) DAC Caiman SEG+Anker PSU DECK 1210 Mat Analog Studio Crystal Mods MN Base/Bearing/Platter+Ebony arm Board Feet Isonoe PSU Paul Hynes SR7EHD-27XL/DCSXL Ag DC lead/Jaeger(low-impedance) connector/3 StageRegs/Recapped PCB+No Pitch/Strobe/Light ARM SME V(Kondo Ag Rewire&Tags) MC Cadenza Black CABLES Arm Yannis SPD-4 IC Yannis 222 Litz+Ag bullets Power WAR PRE ATC SCA2 SPEAKERS ATC 50ASL STANDS Atacama PHONO Sugden Masterclass PA4 SUT Ortofon ST80SE POWER PSAudio P10

    Valve PRECroft Epoch(Mega Modded) AMP Sondex S100 SPEAKERS Tannoy 15"MG+RFC Warwick cabs+ Reference XO DECK Garrard301 MatTeunto GunMetal Bearing SPH Plinth Moldovan Arm SME 3012(Ikeda Ag wired) PSU NSC MCAg Meister SPU/DECCA Maroon CABLES Arm Yannis 420.5 Litz+ Speaker3mm2Ag IC Oyaide FTVS-510 AgWBT 0110Ag Phonostage Paradise


  8. #28
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    I've flung even more questions at Glenn. Poor bloke. I also understand Glenn produces certain mods for people with Tannoy speakers?? This could be interesting and it's yet another area that I'll have to question him (when I feel brave)! I've no idea if the usage of certain brands has any influence over how he designs his amps but I suppose its something else I could ask. Bloody hell this is certainly engrossing to say the least......
    SS CD Teac VRDS25X(Mega Modded) DAC Caiman SEG+Anker PSU DECK 1210 Mat Analog Studio Crystal Mods MN Base/Bearing/Platter+Ebony arm Board Feet Isonoe PSU Paul Hynes SR7EHD-27XL/DCSXL Ag DC lead/Jaeger(low-impedance) connector/3 StageRegs/Recapped PCB+No Pitch/Strobe/Light ARM SME V(Kondo Ag Rewire&Tags) MC Cadenza Black CABLES Arm Yannis SPD-4 IC Yannis 222 Litz+Ag bullets Power WAR PRE ATC SCA2 SPEAKERS ATC 50ASL STANDS Atacama PHONO Sugden Masterclass PA4 SUT Ortofon ST80SE POWER PSAudio P10

    Valve PRECroft Epoch(Mega Modded) AMP Sondex S100 SPEAKERS Tannoy 15"MG+RFC Warwick cabs+ Reference XO DECK Garrard301 MatTeunto GunMetal Bearing SPH Plinth Moldovan Arm SME 3012(Ikeda Ag wired) PSU NSC MCAg Meister SPU/DECCA Maroon CABLES Arm Yannis 420.5 Litz+ Speaker3mm2Ag IC Oyaide FTVS-510 AgWBT 0110Ag Phonostage Paradise


  9. #29
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    Well for the couple of extra quid cost if looks like I'm going with Audio Note silver plated valve bases. Should be getting some more info from Glenn with regards resistor types and a myriad of other questions I asked him. Keep tuned....
    SS CD Teac VRDS25X(Mega Modded) DAC Caiman SEG+Anker PSU DECK 1210 Mat Analog Studio Crystal Mods MN Base/Bearing/Platter+Ebony arm Board Feet Isonoe PSU Paul Hynes SR7EHD-27XL/DCSXL Ag DC lead/Jaeger(low-impedance) connector/3 StageRegs/Recapped PCB+No Pitch/Strobe/Light ARM SME V(Kondo Ag Rewire&Tags) MC Cadenza Black CABLES Arm Yannis SPD-4 IC Yannis 222 Litz+Ag bullets Power WAR PRE ATC SCA2 SPEAKERS ATC 50ASL STANDS Atacama PHONO Sugden Masterclass PA4 SUT Ortofon ST80SE POWER PSAudio P10

    Valve PRECroft Epoch(Mega Modded) AMP Sondex S100 SPEAKERS Tannoy 15"MG+RFC Warwick cabs+ Reference XO DECK Garrard301 MatTeunto GunMetal Bearing SPH Plinth Moldovan Arm SME 3012(Ikeda Ag wired) PSU NSC MCAg Meister SPU/DECCA Maroon CABLES Arm Yannis 420.5 Litz+ Speaker3mm2Ag IC Oyaide FTVS-510 AgWBT 0110Ag Phonostage Paradise


  10. #30
    Join Date: Nov 2010

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    Right I think thats all the research done I have a very good idea of what I want, now its a matter of implementation. Should know more over the weekend and hopefully a date when all this starts. Just listening to the little MicroBasic with some NOS mullard ECC82/3's and it sounds very nice but not quite as muscular as the stock Epoch.
    SS CD Teac VRDS25X(Mega Modded) DAC Caiman SEG+Anker PSU DECK 1210 Mat Analog Studio Crystal Mods MN Base/Bearing/Platter+Ebony arm Board Feet Isonoe PSU Paul Hynes SR7EHD-27XL/DCSXL Ag DC lead/Jaeger(low-impedance) connector/3 StageRegs/Recapped PCB+No Pitch/Strobe/Light ARM SME V(Kondo Ag Rewire&Tags) MC Cadenza Black CABLES Arm Yannis SPD-4 IC Yannis 222 Litz+Ag bullets Power WAR PRE ATC SCA2 SPEAKERS ATC 50ASL STANDS Atacama PHONO Sugden Masterclass PA4 SUT Ortofon ST80SE POWER PSAudio P10

    Valve PRECroft Epoch(Mega Modded) AMP Sondex S100 SPEAKERS Tannoy 15"MG+RFC Warwick cabs+ Reference XO DECK Garrard301 MatTeunto GunMetal Bearing SPH Plinth Moldovan Arm SME 3012(Ikeda Ag wired) PSU NSC MCAg Meister SPU/DECCA Maroon CABLES Arm Yannis 420.5 Litz+ Speaker3mm2Ag IC Oyaide FTVS-510 AgWBT 0110Ag Phonostage Paradise


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