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Old 18th September 2012, 05:00 PM   #21
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I think I am going to try and get a small active pre-amp. I really need some gain when using older ipods.

Mike
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Old 18th September 2012, 05:25 PM   #22
Mooly is offline Mooly  United Kingdom
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Quote:
Originally Posted by ExtraCredit1 View Post
Maybe I am over simplifying this but if my signal is lacking bass when in the lower area of the volume pot (which has more resistance) and sounds good at the top level of the pot (which has lower resistance) then wouldn't adding more resistance make it even worse?

MP
When the pot is on low level settings the ipod sees essentially 10K. Even if you shorted the wiper and the pot were near minimum volume then the ipod still sees around the 10K region. When the pot is turned up the ipod sees a lower resistance (the exact value is dependent on what the pot feeds). So adding a low value resistor across the pot (or ipod output and ground) loads the ipod output stage more normally.

The only way to know for sure is to try it and see Two seconds of a job. If you still have problems then a test sweep played back on the ipod and monitored on a scope would be the best way to see what is going on. Or even use a few fixed frequencies starting at say 20Hz and compare relative levels as frequecy increases.

Edit... one area of confusion. Adding more resistance in parallel as I suggest lowers the overall resistance the ipod sees, not increases it
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Old 18th September 2012, 05:30 PM   #23
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Quote:
Originally Posted by Mooly View Post
When the pot is on low level settings the ipod sees essentially 10K. Even if you shorted the wiper and the pot were near minimum volume then the ipod still sees around the 10K region. When the pot is turned up the ipod sees a lower resistance (the exact value is dependent on what the pot feeds). So adding a low value resistor across the pot (or ipod output and ground) loads the ipod output stage more normally.

The only way to know for sure is to try it and see Two seconds of a job. If you still have problems then a test sweep played back on the ipod and monitored on a scope would be the best way to see what is going on. Or even use a few fixed frequencies starting at say 20Hz and compare relative levels as frequecy increases.


Edit... one area of confusion. Adding more resistance in parallel as I suggest lowers the overall resistance the ipod sees, not increases it


OK that makes sense. So what resistor should I use? and how do I wire it? I assume I put it between the positive and ground on both right and left? so two resistors?

Last edited by ExtraCredit1; 18th September 2012 at 05:35 PM.
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Old 18th September 2012, 05:41 PM   #24
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Is it possible that you have the pot wired backwards, with the ipod (source) connected to the wiper? It'd still control volume, but give some funny effects on tone and distortion.

All good fortune,
Chris
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Old 18th September 2012, 05:46 PM   #25
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Originally Posted by Chris Hornbeck View Post
Is it possible that you have the pot wired backwards, with the ipod (source) connected to the wiper? It'd still control volume, but give some funny effects on tone and distortion.

All good fortune,
Chris
Pretty sure I have it hooked up right but I will triple check. Its also possible that the volume pot is a chinese knock off of the Alps and a piece of crap LOL

MP
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Old 18th September 2012, 05:49 PM   #26
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would I be better off with a 50K pot? I am going to order some from a different vendor and want to get the right one.
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Old 18th September 2012, 05:57 PM   #27
DF96 is offline DF96  England
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Volume pots, used in the normal way, should not do anything much to bass. At most they might reduce bass at maximum if the source output cap is too low in value and the load is too low in resistance i.e. the opposite of what you are seeing. Something isn't what you/we think it is.

Bass will disappear if somehow you are seeing the difference between stereo channels. Is it possible that this could be happening? Does the output use a bridge-mode amp?
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Old 19th September 2012, 06:30 AM   #28
Mooly is offline Mooly  United Kingdom
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Quote:
Originally Posted by ExtraCredit1 View Post
OK that makes sense. So what resistor should I use? and how do I wire it? I assume I put it between the positive and ground on both right and left? so two resistors?
You need two equal value resistors. Anything around the 33 ohm region. Each one is wired as you say, across the output between positive and ground. So that means the easiest point is across the two outer pins of the pot. One for each channel.

Make sure the ground pins of the pot go to the ground (outer part) of the ipod headphone/line out socket.
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Old 23rd September 2012, 07:51 AM   #29
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are you using the headphone connection on the top or are you using an rca connector from an Idock or similar.
There are some articles about this on the net.
I had my Ipod connected by the headphone jack and had the exact same problem.
The bass is completely attenuated unless you run max volume from the Ipod.
If you use the apple connector on the bottom via a cable or a dock you will get much better sound but you will have no volume control via the Ipod
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