Thanks for the info Andrew. I took it down to a gain of 11. I realize that is much higher than you suggested but with my lowest source maxed the amp is almost all the way up. With my loudest source maxed, the amp is on partly but noise is not really noticeable. since these are made, in my case, for less noisy and quieter sources this will work well for now.
Question, how does gain>voume relate? I though 3dB was a doubling of volume. This makes sense to me when you said 4x gain is 12dB, but 11 gain is 20dB?
Question, how does gain>voume relate? I though 3dB was a doubling of volume. This makes sense to me when you said 4x gain is 12dB, but 11 gain is 20dB?
1x = +0dB
2x = +6dB
4x = +12dB
8x = +18dB
16x = +24dB
32x = +30dB
11x is somewhere between +18dB and +24dB
Notice no full stops after deciBell. Never insert a full stop after a proper name used as a unit of measure.
Now if the amp is maxed out, what will volume be like, if gain were reduced by 3dB or by 6dB or by 8.8dB?
2x = +6dB
4x = +12dB
8x = +18dB
16x = +24dB
32x = +30dB
11x is somewhere between +18dB and +24dB
Notice no full stops after deciBell. Never insert a full stop after a proper name used as a unit of measure.
the digital sources should always be maxed out. Only analogue attenuation to be used to reduce digital volume.
Now if the amp is maxed out, what will volume be like, if gain were reduced by 3dB or by 6dB or by 8.8dB?
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Thanks Andrew, makes sense now.
Errrr, I don't know what full stops are unless your talking about light and photography. Do you mean punctuation? If so, maybe we come from different schools. I'm a biologist/ecologist, some journals say no space between number and unit, some require spaces. None would ever remove punctuation after a unit though.
Thanks for the tip about maxing digital sources.
Regarding your question, if source and amp are maxed, your volume will be xdB higher than the source with xdB based on gain. A little googleing suggests a doubling of perceived volume takes 10dB, or 1 bel, of power. Therefore reducing the gain by 10dB would make the volume half as loud. So reducing by 3dB would reduce the perceived volume to 83.5% of original. Figured by 3db = 33% of a bel and since 50% is half of your starting volume, 50*.33=16.5% reduction from original.
Is that right? Math has never been my strength
Errrr, I don't know what full stops are unless your talking about light and photography. Do you mean punctuation? If so, maybe we come from different schools. I'm a biologist/ecologist, some journals say no space between number and unit, some require spaces. None would ever remove punctuation after a unit though.
Thanks for the tip about maxing digital sources.
Regarding your question, if source and amp are maxed, your volume will be xdB higher than the source with xdB based on gain. A little googleing suggests a doubling of perceived volume takes 10dB, or 1 bel, of power. Therefore reducing the gain by 10dB would make the volume half as loud. So reducing by 3dB would reduce the perceived volume to 83.5% of original. Figured by 3db = 33% of a bel and since 50% is half of your starting volume, 50*.33=16.5% reduction from original.
Is that right? Math has never been my strength
An externally hosted image should be here but it was not working when we last tested it.
Lol, sorry Andrew, couldn't resit.
Very informative post otherwise.
Is there an impact on battery life with maxed out digital sources like mp3 players?
I want to make a very similar project. I started working in eagle and noticed something weird with your images on the first page of this topic. The eagle screen shots are looking *through* the board. That's why everything looks backwards. The problem is that your photo of the bottom of the PCB looks the same. That is, I think, everything is reversed. That's why your 317 terminals were reversed, your zener was in backwards, etc. I don't know how your amp works at all really. Am I crazy?
I usually "Export... image", print with laserjet, and then use a laminator. The iron should work the same and you should not have to "flip" the image before printing. Did you "flip" it???
I usually "Export... image", print with laserjet, and then use a laminator. The iron should work the same and you should not have to "flip" the image before printing. Did you "flip" it???
Hi Digits,
my english grammar is poor.
I know only a few of the rules. I was once pulled up in an Email for splitting an infinitive. I had to go round to see the computer whiz kid to find out what I had done wrong.
Some years later I realised I had forgotten the rule and now can't even remember what infinitive I had split.
But, I am an engineer not a linguist. I do try to be technically accurate otherwise confusion reigns.
But I do like the way folk/Members can pull up graphics about any subject from seemingly any source to elucidate a point. I wish I had that ability.
I was looking at the PCB again. For parts that are symmetric reversing the image doesn't matter and if you swap left for right on both the input jack (tip and ring) and the output, then I guess you're good there, too.
One other thing, I have found that I have to let the sharpie ink corrections dry overnight or I get the burn through like you have on the ground-bus and smiley face I know it's a real PITA, but you have to "resist" the urge.
One other thing, I have found that I have to let the sharpie ink corrections dry overnight or I get the burn through like you have on the ground-bus and smiley face
I know it's a real PITA, but you have to "resist" the urge. 
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