Hi, looking to do a simple mod/improvement on my Pioneer A400. Just wondering if removing then bypassing the headphone output will improve the sound of the amp. 
you can find the schematics for the A400 here (not sure how else i can attach them sorry)
http://www.hifiengine.com/manuals/pioneer/a400.shtml
you can find the schematics for the A400 here (not sure how else i can attach them sorry)
http://www.hifiengine.com/manuals/pioneer/a400.shtml
I think you will need a good imagination to detect any difference in the sound at the speakers, by doing this mod.
However, there are folks on this forum who can (?) tell the sound difference between different brands of switches, RCA jacks, etc. so it might be best to consult them.
Cheers
John
hi john, the reason i am interested in doing this is that i recently bypassed the input selector and was rewarded with a HUGE improvement in sound quality - mainly the level of detail improved significantly. anyone with a pair of ears who isnt deaf would have noticed the improvement.
my thought is that by bypassing the headphone output i will shorten the signal path and remove an obstacle from it as well thus improving the final output.
anyone else?
my thought is that by bypassing the headphone output i will shorten the signal path and remove an obstacle from it as well thus improving the final output.
anyone else?
And this improvement was verified by a double-blind test comparing modified and non-modified receivers....?
Or you 'remembered' the sound from before the mod?
Whatever works for you- after all, this is just a recreational hobby, nothing serious.
John
Wow John that was subtle! If you are doubting what i am saying about the improvement without having any experience or involvement in the process then you might be jumping the gun a bit.
To answer your question, yes i can remember what the amp sounded like before i did the mod. i have been listening to the same amp and the same music everyday for ages so i know what it sounds like.
actually, given the state of the component i removed and the quality of the silver wire i replaced it with, i find it ridiculous that anyone would believe there could not be an improvement in sound quality.
yes this may be a hobby but i love music and love listening to it so for me this is something i take seriously - though i dont take myself too seriously.
the clue is in the (user)name!
To answer your question, yes i can remember what the amp sounded like before i did the mod. i have been listening to the same amp and the same music everyday for ages so i know what it sounds like.
actually, given the state of the component i removed and the quality of the silver wire i replaced it with, i find it ridiculous that anyone would believe there could not be an improvement in sound quality.
yes this may be a hobby but i love music and love listening to it so for me this is something i take seriously - though i dont take myself too seriously.
the clue is in the (user)name!
I have not downloaded the schematic, but it should be obvious that we are talking about two different things here. I assume that, as in most amps, the headphone is connected via a resistor to the amp output. No headphone, no loading the circuit. As this is on the amps output, the impedance there is very low, and the resistor plus the headphone have a much higher impedance than the speakers, so really no loading. You may remove it if you don't use headphones, but it shouldn't make a difference.
But on the input, your impedance is high, so the wiring is a bit more critical. However, no way should you get a HUGE difference when you bypass the input selector, unless something was wrong to begin with, e.g. a ground loop. I'm assuming, that you did this with a line input (e.g. CD or Tuner). Or was it the Phono-input?
There is something else you can try, which often makes some real difference: Bypass the speaker selector switches at the output (if there are any in your amp and you don't need them). Here you have high currents flowing. Connect the speaker terminals directly to the transitor outputs by using a short piece of speaker cable. If you do this and remove all unnecessary wiring, you also are disconnecting the headphone output at the same time.
Kurt
But on the input, your impedance is high, so the wiring is a bit more critical. However, no way should you get a HUGE difference when you bypass the input selector, unless something was wrong to begin with, e.g. a ground loop. I'm assuming, that you did this with a line input (e.g. CD or Tuner). Or was it the Phono-input?
There is something else you can try, which often makes some real difference: Bypass the speaker selector switches at the output (if there are any in your amp and you don't need them). Here you have high currents flowing. Connect the speaker terminals directly to the transitor outputs by using a short piece of speaker cable. If you do this and remove all unnecessary wiring, you also are disconnecting the headphone output at the same time.
Kurt
Sorry about the confusion guys - i really should have posted this photo earlier to show you what I was dealing with in terms of the input selector:
Now hopefully you can see the extent of the corrosion/oxidisation evident directly in the signal path.
Javin5, thanks for your input, unfortunately I dont have speaker switching but atleast I wont waste my time with the headphone output now.
An externally hosted image should be here but it was not working when we last tested it.
Now hopefully you can see the extent of the corrosion/oxidisation evident directly in the signal path.
Javin5, thanks for your input, unfortunately I dont have speaker switching but atleast I wont waste my time with the headphone output now.
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