I wonder if you might have any pointers kind Sir? I'm currently working on my Pioneer A400 and I notice you have mentioned in previous threads that you have “modded” a few of these in the past. The story begins when I noticed my A400 wasn't sounding quite as good as it used to, I decided it was time to replace some capacitors. I have replaced capacitors in various HiFi and Av equipment in the past. The sound was still punchy and dynamic but a little rough at the top end. First of all I replaced the old Elna 10000uF 50V smoothing caps with Nichicon Gold series ones of the same value. Then I replaced the 2.2uf 50v coupling caps, again with Nichicon gold series, off the top of my head I think their location is c201 and c202 on the schematics. (I wrote to Tom Evans and the Nichicon caps were his recommendation) I've also re biased the amp, I've adjusted to voltage at the biasing pots with a meter at both the large white 330k resistors to 60mv. Can this be increasd further? However, there is something missing, The amp has lost it's dynamic slam and the Bass is a little light,it's sounding as if as though something is holding it back and a little flat, however it now has a fluid, smooth mid to top end. Any ideas what else I can do to improve matters in the low end of this amp, I am I going to have to replace all the caps or is there something else I should do? Thanks. Tesler
Pioneer A400 Mod question for ifitsoundsgoodlistentoit Please
- Thread starter Tesler
- Start date
I'm not competent enough to do my own internal mods, I've used Fidelity Audio to mod my DAC and AV Receiver. Try speaking to Brent there, he's very helpful and I'm sure he'll offer you a few words of advice (especially if you buy the components from him).
Hi Tesler, in terms of replacing more caps, well you can do it but i have to be honest and say that after replacing the caps you have mentioned (the Smoothing caps(10000uF) and the Coupling caps(2.2uF)) and then going on to recap the rest of the amp i didnt actually notice much, if any, difference.
I am surprised that you are now finding the bottom end is lacking though as when i replaced the Smothing Caps with Mundorf M-lytic SI caps (even though the amp already sounded fine) i found that the bass become much more extended and gained some weight. These caps are about £10 each so you could try experimenting...
The caps I used to replace the Coupling Caps were ANSAR SUPERSOUND Polypropylene Audio Capacitors from Crinklewood Electronics. I used these based on recommendations from other A400 modders. £3 each and about the size of a AA battery so not easy to fit but very worthwhile in terms of sound quality! There was a huge increase in detail with these new caps - which isnt surprising given that they are the only caps on the entire board that the audio signal passes through.
With regards to the bias settings i would not go any higher than 60mV - i think i set mine around 58mV as one of the pots had topped out at that.
Other, very worthwhile gains in detail and bass weight can be had from replacing the copper cable leading to and from the transformer with solid silver wire.
Have you replaced the hardwired mains cable with an aftermarket one yet? If you have, then replacing the internal copper cable will reinforce the benefits of this cable.
Other than that, there are a bunch of resistors directly in the signal path that can also be replaced for better quality parts.
Also, if you only ever use one input on the amp let me know and I can tell you a mod that will blow your mind with the increase of detail!
I am surprised that you are now finding the bottom end is lacking though as when i replaced the Smothing Caps with Mundorf M-lytic SI caps (even though the amp already sounded fine) i found that the bass become much more extended and gained some weight. These caps are about £10 each so you could try experimenting...
The caps I used to replace the Coupling Caps were ANSAR SUPERSOUND Polypropylene Audio Capacitors from Crinklewood Electronics. I used these based on recommendations from other A400 modders. £3 each and about the size of a AA battery so not easy to fit but very worthwhile in terms of sound quality! There was a huge increase in detail with these new caps - which isnt surprising given that they are the only caps on the entire board that the audio signal passes through.
With regards to the bias settings i would not go any higher than 60mV - i think i set mine around 58mV as one of the pots had topped out at that.
Other, very worthwhile gains in detail and bass weight can be had from replacing the copper cable leading to and from the transformer with solid silver wire.
Have you replaced the hardwired mains cable with an aftermarket one yet? If you have, then replacing the internal copper cable will reinforce the benefits of this cable.
Other than that, there are a bunch of resistors directly in the signal path that can also be replaced for better quality parts.
Also, if you only ever use one input on the amp let me know and I can tell you a mod that will blow your mind with the increase of detail!
Thanks for your replies,
It's puzzling me as to what's happened to the dynamics here. I've tried Mundorf Mylytics in an A400 before, they improved bass, but altered the top end too much.
I've even tried fitting the old Elna caps back in and the amp still lacks dynamic punch, there is clearly something not right here, maybe I might have damaged something on the track when removing the original caps?
I've gone over the circuit board looking for dry solder joints and found nothing, except for a break in one of the joints on the Headphone socket which I repaired.
I've tried my cd player in all the inputs and my project audio debut in the phono input.
I use all the inputs on my A400, and no I've not replaced the mains cable and socket yet although that mod is next on my list when I can suss out what's causing the loss of dynamics first. I'm not sure what to do next or where to look to resolve the issue.
Thanks for your replies anyway.
Cheers for now.
It's puzzling me as to what's happened to the dynamics here. I've tried Mundorf Mylytics in an A400 before, they improved bass, but altered the top end too much.
I've even tried fitting the old Elna caps back in and the amp still lacks dynamic punch, there is clearly something not right here, maybe I might have damaged something on the track when removing the original caps?
I've gone over the circuit board looking for dry solder joints and found nothing, except for a break in one of the joints on the Headphone socket which I repaired.
I've tried my cd player in all the inputs and my project audio debut in the phono input.
I use all the inputs on my A400, and no I've not replaced the mains cable and socket yet although that mod is next on my list when I can suss out what's causing the loss of dynamics first. I'm not sure what to do next or where to look to resolve the issue.
Thanks for your replies anyway.
Cheers for now.
hi Tesler, one thing that may have happened is you may have installed a cap out of phase - ie. polarity reversed. just have a quick look to make sure they're all good. im really stumped by this.
also worth setting the bias back as it was to see what happens.
if you arent happy with the sound of the amp after a mod then the best thing to do is eliminate the variables one-by-one until you find the culprit. good luck!
also worth setting the bias back as it was to see what happens.
if you arent happy with the sound of the amp after a mod then the best thing to do is eliminate the variables one-by-one until you find the culprit. good luck!
Thanks for your reply once again,
I don't think I've installed the caps out of polarity, I know what happens if you install an electrolytic capacitor the wrong way round (Fizz Bang). We used to annoy the electronics tutor at college, many moons ago, by purposely fitting an electrolytic cap the wrong way round in a power supply just for a laugh, although he didn't find us very funny.
I'll try re-biasing the amp back to the settings Pioneer state, I'll see if this improves matters.
I'm suspicious of another faulty cap or two somewhere, as you say I'll just have to go through a process of elimination until I find the culprit.
I recently found an interesting thread here:
http://www.diyaudio.com/forums/solid-state/34327-pioneer-a400-coupling-caps.html
I'm unable to source Black Gates anywhere, I believe they aren't manufactured anymore, but this thread is a good pointer as to what to replace.
I'll try replacing everything that is suggested and see what gives.
Cheers
I don't think I've installed the caps out of polarity, I know what happens if you install an electrolytic capacitor the wrong way round (Fizz Bang). We used to annoy the electronics tutor at college, many moons ago, by purposely fitting an electrolytic cap the wrong way round in a power supply just for a laugh, although he didn't find us very funny.
I'll try re-biasing the amp back to the settings Pioneer state, I'll see if this improves matters.
I'm suspicious of another faulty cap or two somewhere, as you say I'll just have to go through a process of elimination until I find the culprit.
I recently found an interesting thread here:
http://www.diyaudio.com/forums/solid-state/34327-pioneer-a400-coupling-caps.html
I'm unable to source Black Gates anywhere, I believe they aren't manufactured anymore, but this thread is a good pointer as to what to replace.
I'll try replacing everything that is suggested and see what gives.
Cheers
Hi Tesler,
yeah that thread is where i started with my mods. I wouldnt worry too much about the other caps mentioned though - i really found no difference when i replaced them as opposed to a huge difference when i replaced the coupling caps. Also, if they werent responsible for the loss of dynamics before they still shouldnt be!
Something that just popped into my head is the possibility that if you have removed the PCB to do any of this modding you may have wired back to the transformer with the wires reversed - which theoretically shouldnt make a difference but just maybe... im clutching at straws here...
sorry i cant be more help
yeah that thread is where i started with my mods. I wouldnt worry too much about the other caps mentioned though - i really found no difference when i replaced them as opposed to a huge difference when i replaced the coupling caps. Also, if they werent responsible for the loss of dynamics before they still shouldnt be!
Something that just popped into my head is the possibility that if you have removed the PCB to do any of this modding you may have wired back to the transformer with the wires reversed - which theoretically shouldnt make a difference but just maybe... im clutching at straws here...
sorry i cant be more help
MMM yes I know where you are going with that about the transformer wiring.
However whenever I work on any wired connections, the first thing I do is steal some of the wife's nail varnish, of various colours, and mark terminals and leads with colours, (a bit like we used to do with the spark plugs and HT leads in the old minis, you know, incase one of your joker mates changed the HT leads round for a laugh). Also, I take photographs from different angles of the area I'm working on, so if I get lost with reconnection I just refer to the colours and photos.
When I replaced the smoothing caps and coupling caps I just very carefully lifted the board out of the chassis with the transformer wires still connected, it's a bit tight but I could gently support the main board and can get easy access to the solder joints underneath without having to unwire the transformer, I did however check the transformer connections after re-assembly.
I'd be interested to know what components you used to replace the coupling caps?
What are the part names and numbers and where can I source these from?
Thanks again
Tes.
However whenever I work on any wired connections, the first thing I do is steal some of the wife's nail varnish, of various colours, and mark terminals and leads with colours, (a bit like we used to do with the spark plugs and HT leads in the old minis, you know, incase one of your joker mates changed the HT leads round for a laugh). Also, I take photographs from different angles of the area I'm working on, so if I get lost with reconnection I just refer to the colours and photos.
When I replaced the smoothing caps and coupling caps I just very carefully lifted the board out of the chassis with the transformer wires still connected, it's a bit tight but I could gently support the main board and can get easy access to the solder joints underneath without having to unwire the transformer, I did however check the transformer connections after re-assembly.
I'd be interested to know what components you used to replace the coupling caps?
What are the part names and numbers and where can I source these from?
Thanks again
Tes.
Sorry, ifitsoundsgoodlistentoit.
I think you may have answered my question earlier?
Crinklewood Electronics!
Is this the part?
Ansar Polypropylene Axial Audio capacitor Part number CPW2U2 2.2uF 450V?
450v is a bit more than the 50v ones the replace but I suppose that doesn't really matter?
Cheers.
I think you may have answered my question earlier?
Crinklewood Electronics!
Is this the part?
Ansar Polypropylene Axial Audio capacitor Part number CPW2U2 2.2uF 450V?
450v is a bit more than the 50v ones the replace but I suppose that doesn't really matter?
Cheers.
Yeah those are the bad boys. As stated previously beware that they are huge! About the size of an AA battery but you can mount them easily enough by laying them horizontally on the PCB - i secure mine with a blob of blutack. make sure you dont trim the leads until you have positioned them as you need long leads.
yes the 450v rating is irrelevant.
good luck - i await your finding eagerly.
yes the 450v rating is irrelevant.
good luck - i await your finding eagerly.
WOW, talk about first class service, I ordered these yesterday lunchtime from Cricklewood via my desk pc in the office where I work in Glasgow . As type this at 8:25 am this morning sitting at the very same desk I have them in my possesion.
Yes, you weren't kidding when you said they are huge!
Just a question before I fit these tomorrow, do they have a polarity? I don't see a +ive or-ive marked on them anywhere? do they have to be fitted a certain way round or does it not matter with these.
Both the legs are the same length, usualy the +ive has a longer leg then the -ive but both these legs are the same length out of the packaging?
Thanks.
Yes, you weren't kidding when you said they are huge!
Just a question before I fit these tomorrow, do they have a polarity? I don't see a +ive or-ive marked on them anywhere? do they have to be fitted a certain way round or does it not matter with these.
Both the legs are the same length, usualy the +ive has a longer leg then the -ive but both these legs are the same length out of the packaging?
Thanks.
no, these are bi-polar caps so it makes no difference - though i have read that its best to install them (and other bi-polars) so that the signal flows in the same direction as the text printed on the cap.
im am curious to see how you get on with these caps - because my A400 is the GTE model which Tom Evans had modded before i started fiddling with it, it already had upgraded coupling caps. However, these Ansars are in a different league!
How did you get on with the bias?
im am curious to see how you get on with these caps - because my A400 is the GTE model which Tom Evans had modded before i started fiddling with it, it already had upgraded coupling caps. However, these Ansars are in a different league!
How did you get on with the bias?
Well thats the Ansar caps fitted and amp re biased and im just running it now.
O.M.G that's done it, dynamics are back, Treble is smooth and clean, Bass way improved, this amp sounds fantastic now.
Oh, and whilst I was about it, I replaced the old red power LED with a nifty blue one.
Thats me off now to play cd's now.
Thanks for all the pointers and your cap recomendation.
Thats the cambridge Audio 740a is was using in the mean time now relagated to the spare room.
Cheers.
Tes
O.M.G that's done it, dynamics are back, Treble is smooth and clean, Bass way improved, this amp sounds fantastic now.
Oh, and whilst I was about it, I replaced the old red power LED with a nifty blue one.
Thats me off now to play cd's now.
Thanks for all the pointers and your cap recomendation.
Thats the cambridge Audio 740a is was using in the mean time now relagated to the spare room.
Cheers.
Tes
Hi Tes, thats great to hear! Was the bias set right then? or was it just the news caps that have helped?
Im happy youve got it running right and glad i could be of assistance.
Mod On!
Im happy youve got it running right and glad i could be of assistance.
Mod On!
Hi, I read with great interest your opinions about changing the old elna 10000uf caps with nichicon 10000uf. For me the sound is poorer than before, more cold. So I replaced them whit a pair new elna audio 10000uf find in web brand new. The best for my a-400! I'm interested now in changing the 2.2uf 50v coupling caps just to try...But where are they? Could you please send me a picture of theyr location? Can you kindly help me? I let you my email address: linotommasini@tiscali.it Thank you lino
eggontoast
Well-known member
I have just read this whole thread and I must say I have never read such ill informed twaddle in my life.
The blind leading the blind.........
The blind leading the blind.........
eggontoast said:
If that's the most positive contribution you can make to a thread, eggontoast, probably best not to bother.
eggontoast
Well-known member
You may be right Andrew but, there are going to be people out there who read this thread and take it as gospel when in truth 90% of it is complete nonsenseAndrew Everard said:
marxelinus said:
Hi Lino,
Often when replacing capacitors it can be a matter of personal taste as to whether you like the results. Tesler replaced his Elnas with Nichicon and liked what he heard. I replaced my Elnas with Mundorf Mylitic SI's and liked what I heard - different strokes...
If you are interested in changing the coupling caps then I would recommend, as i did to Tesler, that you try the ANSAR Supersound Polypropylene Caps from Crinklewood Electronics - they are only a few £'s each and sound sublime.
Their location on the PCB is C201/C202 - I will email a photo when I have finished posting this.
Chris
eggontoast said:
I would love to know what pearls of wisdom you have to offer us on this topic mate!
I may not have much, if any techinical knowledge, but I do have plenty of practical knowledge/experience when it comes to modding the A400 which is why I am prepared to share it with others. They can judge for themselves whether they think I am capable of providing this advice and whether they will accept this advice.
If this wasnt so then Im sure the mods would tell me not to post...
eggontoast
Well-known member
eggontoast said:
Someone has been getting out the wrong side of the bed lately. If you think there is something wrong with the info provided then just politely correct it or give advice of your own rather than pointless and unconstructive posts...
eggontoast said:
Seriously you are getting on my nerves. What is your problem? Not only do I go out of my way to help others with any problems with their A400s but I am also humble enough to confess to not being an expert.
All you do is criticise without explanation or reason and you contribute absolutley nothing.
If you have nothing positive to add then dont post!
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