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.....

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.

What value are the PSU Reserviour caps?

10,000 uF 50v

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 :scratch: Manufacturer & type would be handy to :)

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Originally Posted by Reid Malenfant

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 :scratch: Manufacturer & type would be handy to :)

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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.

Quote:

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Originally Posted by Jac Hawk

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.....

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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

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

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.

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

Quote:

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Originally Posted by Andre

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

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Not sure if the split foils will fit directly on the board, i may be able to mount them on a seperate board and mount them horizontally, then run connectors to the main board, this would also mean that i could mount the 4 parallel caps and the rectifier could be changed, if it can be done it would be a much tidier job, but space is the major factor.

Snap in's 10mm centres The cans are 35mm Dia x 60mm Tall !

Another option is the Kendeil KO5 caps, not slits but very good & smaller, i just fitted a pair in another amp yesterday, the amp sounds tons better

Quote:

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Originally Posted by Andre

Snap in's 10mm centres The cans are 35mm Dia x 60mm Tall !

Another option is the Kendeil KO5 caps, not slits but very good & smaller, i just fitted a pair in another amp yesterday, the amp sounds tons better

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The 2 caps on the board at the moment are ELNA's 30mm dia x 40mm, i have a maximum of 60mm from the board to the lid, so instead of mounting the new caps on the board i will clip them to the chassis and run leads to the pcb, which will mean i can use just about any cap i want

See you're back on AoS Mike, how did you get on with this? I've just picked up an A400 myself.

Quote:

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Originally Posted by Jac Hawk

The 2 caps on the board at the moment are ELNA's 30mm dia x 40mm, i have a maximum of 60mm from the board to the lid, so instead of mounting the new caps on the board i will clip them to the chassis and run leads to the pcb, which will mean i can use just about any cap i want

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Sorry very late to the party, Need to upgrade my A400 and am looking for any help. I have seen a suggestion that replacing the ceramic capacitors for film capacitors gives huge improvement in sound can anybody suggest which film capacitor is best to use. Any other suggestions would be appreciated.

I think it was Tom Evans of Trichord that did the A400 GTE and possibly other upgrades to the A400. Here is a link to an old thread on PFM that you might find interesting.

https://pinkfishmedia.net/forum/thre...ecrets.108523/

I had a Trichord Genesis CD player (based on a Pioneer player) and Tom Evans was offering further upgrades and I had a chat with him about them. Might be worth giving him a call about your plans for the A400

This is his website : http://www.audiodesign.co.uk/

Quote:

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Originally Posted by Puffin

I think it was Tom Evans of Trichord that did the A400 GTE and possibly other upgrades to the A400. Here is a link to an old thread on PFM that you might find interesting.

https://pinkfishmedia.net/forum/thre...ecrets.108523/

I had a Trichord Genesis CD player (based on a Pioneer player) and Tom Evans was offering further upgrades and I had a chat with him about them. Might be worth giving him a call about your plans for the A400

This is his website : http://www.audiodesign.co.uk/

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Thanks puffin the pinkfishmedia article was very interesting, I wish I had studied electronics in my youth. I am Ok with a soldering Iron but electronic knowledge is very basic. I propose to replace the Ceramics with Polystyrene can anybody say if that is a good move.

Yes polystyrene is a very good choice. Just make sure the voltage rating is adequate for the intended position, as some polystyrene are only rated at 50V.