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Thread: Pioneer A400 Upgrade Help Required

  1. #1
    Join Date: Nov 2010

    Location: Chorley, Lancs

    Posts: 1,902
    I'm Mike.

    Default Pioneer A400 Upgrade Help Required

    Hi guys, I recently got a Pioneer A400 amp off eBay, it's in great condition, but i'm now looking to do some upgrades to it i.e. Tom Evans esque.

    Andre sent me a link to another forum (cheers mate, you're a star) where there was quite a lengthy discussion, my questions are -:
    1. Have any of you guys done an A400 upgrade
    2. If so, what's worth changing
    3. Does anyone have a parts list they could let me have, as it would save me trawling through the schematics
    4. Finaly, any suggestions on cap/resistor makes / models that would compliment the A400.

    Thanks.....

  2. #2
    Join Date: Nov 2010

    Location: Chorley, Lancs

    Posts: 1,902
    I'm Mike.

    Default

    well since i've been sat on my arse all day (snowed in) i've put together the parts list, and i've got a pretty good idea of makes i will use.

    So what i was going to do is take photo's of the job while doing it, then post a step by step guide on how to do the upgrade, including parts list etc..

    Let me know if anyone is remotely interested in the A400 GTE mod, i've been looking for a guide or at least the parts list for a few nights now with no luck, and a post like this would have saved me a lot of time, as i've said let me know if you guys think it's a good idea and i'll do it.


    As the late Colonel Sanders once said
    "I'm too drunk to taste this chicken!!"

  3. #3
    Join Date: Dec 2008

    Location: Yorks

    Posts: 16,649
    I'm Nobody.

    Default

    What value are the PSU Reserviour caps?

  4. #4
    Join Date: Nov 2010

    Location: Chorley, Lancs

    Posts: 1,902
    I'm Mike.

    Default

    10,000 uF 50v


    As the late Colonel Sanders once said
    "I'm too drunk to taste this chicken!!"

  5. #5
    Join Date: Jul 2010

    Location: North Cambs UK, Earth, Sol, Orion - Cygnus arm of galaxy

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    I'm MadeOfDeadGiantStarsThatExplodedEonsAgo.

    Default

    It'd be nice to get hold of a circuit diagram & then see what components are fitted in the most critical positions. Im sure it'd be worth modifying but as it's already not a bad apple some care will be needed to get more performance out of it imo

    When you say 10,000uf 50V how many of these are there? Just the two or is there 4 of them or whatever Manufacturer & type would be handy to
    Bests, Mark



    "We must believe in free will. We have no choice" Isaac Bashevis Singer

  6. #6
    Join Date: Nov 2010

    Location: Chorley, Lancs

    Posts: 1,902
    I'm Mike.

    Default

    Quote Originally Posted by Reid Malenfant View Post
    It'd be nice to get hold of a circuit diagram & then see what components are fitted in the most critical positions. Im sure it'd be worth modifying but as it's already not a bad apple some care will be needed to get more performance out of it imo

    When you say 10,000uf 50V how many of these are there? Just the two or is there 4 of them or whatever Manufacturer & type would be handy to
    aparantly the a400 is a great little amp to upgrade (one of the reasons i got it) as i've said i'm going for the full recap as well as tweeking the bias, most articles i've read say it makes an astounding difference to the sound so i guess we'll see.

    yes just the 2 smoothing caps, i think they're elna's and if you want a look at it i have the full service manual in pdf including scematics and pcb diagrams.


    As the late Colonel Sanders once said
    "I'm too drunk to taste this chicken!!"

  7. #7
    Join Date: Mar 2008

    Location: Wales, UK

    Posts: 321
    I'm Mark.

    Default

    Quote Originally Posted by Jac Hawk View Post
    Hi guys, I recently got a Pioneer A400 amp off eBay, it's in great condition, but i'm now looking to do some upgrades to it i.e. Tom Evans esque.

    Andre sent me a link to another forum (cheers mate, you're a star) where there was quite a lengthy discussion, my questions are -:
    1. Have any of you guys done an A400 upgrade
    2. If so, what's worth changing
    3. Does anyone have a parts list they could let me have, as it would save me trawling through the schematics
    4. Finaly, any suggestions on cap/resistor makes / models that would compliment the A400.

    Thanks.....
    Hi

    I have modified several A400 amplifiers over the years.

    The volume control is a good place to start. We use to install the DACT CT2 attenuators and remove the balance control.

    If you can get hold of a Tom Evans GTE version it is a better platform to build on.

    Best,
    Mark
    Mark @ Audiocom, Wales UK - 01646 650008

    Website

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  8. #8
    Join Date: Dec 2008

    Location: Yorks

    Posts: 16,649
    I'm Nobody.

    Default

    Well i'm in the middle of a Quad '306' i'll be changing the 4x 4,700uF PSU caps for Mundorf Mlytic 6800uF/63V..bypass each with Kimber Kap 5.0uF + 0.01uF providing i can get the 5.0uF in there! when they arrive that is

  9. #9
    Join Date: Nov 2010

    Location: Chorley, Lancs

    Posts: 1,902
    I'm Mike.

    Default

    So like i said i've got the list of caps they are as follows

    Capacitors

    A full possible list would be

    4 x 2.2 uF 50v
    4 x 3.3. uF 100v
    4 x 10 uF 50v
    2 x 100 uF 50v
    2 x 220 uf 16v
    2 x 330 uF 10v

    The most important ones are

    4 x 2.2 uF 50v

    Followed by

    2 x 330 uF 10v
    2 x 10 uF 50v

    Followed by the rest.

    For the power section

    2 x 10,000 uF 50v
    3 x 10 uF 50v
    1 x 47 uF 25v

    My thinking is to go for polly caps for the output stages such as mundorf m supremes, elna cerafines for the rest, and on the psu, maybe mundorf mlytics for the 2 large smoothing caps.

    I'm kinda fishing for suggestions here, so any help would be very welcome.


    As the late Colonel Sanders once said
    "I'm too drunk to taste this chicken!!"

  10. #10
    Join Date: Dec 2008

    Location: Yorks

    Posts: 16,649
    I'm Nobody.

    Default

    A bigger imporovement for the PSU cap would be slit foils, i physically can't get em in my Quad

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