DocLorren said:
Hmm, I took great care to deliver explanations to every term I used, proove my measurements with pictures, support my results with mathematical background, give links to read up - and answer questions as they came...
I think the main problem is that the thread starter confused peak voltage, average voltage, and level. And then didn't manage to read thoroughly...
As of my perception, someone with the plan to actually build a variable gain stage circuit should be aware of certain important basics. If some terms are new to the reader - or some explanations sound too long to follow easily - I would consider it a good opportunity (and a good point in time) to gain the knowledge that will definitely required down the course of this project anyway.
sek said:
I think the main problem is that the thread starter confused peak voltage, average voltage, and level. And then didn't manage to read thoroughly...
actually, im quite very familiar with those concepts. what i asked, if you'd read my posts, was what was the RMS output of the 1/8 stereo out of an ipod. i said if you only knew the peak i could convert to RMS.
oh yeah, and i already built two circuits that boost the ipod to stereo line level. so, sek, i HAVE actually built a variable gain stage circuit before even starting this thread. so, don't assume because someone asks what you perceive as a dumb question that the person asking it is dumb also.
as i said earlier, i was hoping people would share their designs for ipod/stereo interfacing. thank you.
gain said:
I honestly didn't do so, fellow DIYer. It just ceases to amaze me how many repetitions needed to occur in this thread (question clearance, device determination, number games, etc.). I claimed this to be rooted in your constantly changing your mind and your not reading thoroughly. Dumbness is (and was) not my assumption! That's all.
As I said, I doubt this. First you confused voltages (Vrms, Vpeak) with each other and with the term level. Then you couldn't handle the unit conversion (and the unit decibels), which you actually should be familiar with from your former builds. All I want to do is to be of help, really.
Yes, but for whatever reasons, you need help on a new one.
Now that we mention it, what's the deal with your other gain stages? Why aren't they suitable to your needs?
Of what we heard so far, what you need is a single supply line stage with trimmable gain (i.e. a trimmer as gain resistor). Add a potentiometer in front of it and you're all set. This tutorial gives all the details, it even contains a calculation example of a stage with gain of +10, which is exactly what you need. As an opamp I recommend Texas Instrument's OPAx353 or any other single supply opamp.
Here's some literature: Designing Gain and Offset in Thirty Seconds and the Op Amps for Everyone Design Guide (Rev. B), both by Texas Instruments. The latter will show in every detail how to use even ultra precison opamps in a single supply application.
Maybe you can't find any project (and don't get any feedback on your question) because your problem is too specific. Instead, take a look into any headphone preamplifier project intended for battery use. They show how to generate an opamp supply out of 12V (or the like) and connect quality opamps. Google knows how to find DIY headphone projects, first hit is the good old CMOY (of which figure 2 is your desired circuit and figure A2 the solution to your problem).
sek said:
As I said, I doubt this. First you confused voltages (Vrms, Vpeak) with each other and with the term level. Then you couldn't handle the unit conversion (and the unit decibels), which you actually should be familiar with from your former builds. All I want to do is to be of help, really.
i never even attempted these conversions.
sek said:
Yes, but for whatever reasons, you need help on a new one.
i asked for people to share circuits that they had had success with in the past. this is hardly a cry for help, imo.
sek said:
never said they wern't. my op was a question about RMS output from ipods.
sek said:
that is great info. thank you.
im kidding with you, Andrew!
don't you know i started this thread secretly knowing it would amuse you?
jk ... respect to you Andrew. this thread feels like when you ask one of those simple questions and the someone who answers must feel the need to complicate the issue so profusely in order to make themselves and what they do sound more important than they really are. its a self esteem issue mostly, sometimes comical to watch.
don't you know i started this thread secretly knowing it would amuse you?
jk ... respect to you Andrew. this thread feels like when you ask one of those simple questions and the someone who answers must feel the need to complicate the issue so profusely in order to make themselves and what they do sound more important than they really are. its a self esteem issue mostly, sometimes comical to watch.
oh yeah, something else i thought i'd share because no one mentioned it to me.
you don't need a gain stage to plug an ipod into a stereo line in. just a cord with a 1/8 stereo male on one end and two RCA males on the other. connect them together, crank the ipod to the max, and the input level is very close (a little less) than what the stereo is expecting but not by much. you will still hear the ipod just fine. the gain stage just gives the signal a little more 'oomph', but again, not necessary to enjoy your ipod through your stereo.
peace.
you don't need a gain stage to plug an ipod into a stereo line in. just a cord with a 1/8 stereo male on one end and two RCA males on the other. connect them together, crank the ipod to the max, and the input level is very close (a little less) than what the stereo is expecting but not by much. you will still hear the ipod just fine. the gain stage just gives the signal a little more 'oomph', but again, not necessary to enjoy your ipod through your stereo.
peace.
To whom it may concern,
making a fool of me is totally uncalled for, 'dude'!
And now turning the story backwards and claiming you knew everything and actually asked for nothing is just ridiculous, honestly!
As Andrew subliminally mentions, someone special really needs to reread this thread, but it certainly won't be me!
You're just odd, 'dude'!
making a fool of me is totally uncalled for, 'dude'!
And now turning the story backwards and claiming you knew everything and actually asked for nothing is just ridiculous, honestly!
As Andrew subliminally mentions, someone special really needs to reread this thread, but it certainly won't be me!
You're just odd, 'dude'!
sek said:
making a fool out of you was not my intentions. pointing out the erroneous statements you made was. i feel bad if i offended you. besides, YOU are the only person who can give someone permission to make a fool of yourself
sek said:
And now turning the story backwards and claiming you knew everything and actually asked for nothing is just ridiculous, honestly!
go back and reread my original post. it was a question asked, not a claim of omnipotence.
sek said:
why not? if you have some sort of problem with me be a man (or woman or whatever you are) and take it up with me yourself. if sure you can figure out how to PM if you are as knowledgeable as you claim.
Instead of going to Kindergarden again, I'll just make a couple of quotations, highlighting some areas in order to support my point.
Here the problem begins with some general misconception about the relation between an electrical change and the corresponding audible change in level:
The trouble is that it leads to some guesswork which, while looking educated, is in fact way off:
Here's some proof of my claim about general lack of understanding:
Here the problem begins with some general misconception about the relation between an electrical change and the corresponding audible change in level:
The main misconceptions here are that turning the knob in hifi gear will lead to some standardized or proportional behaviour and that - on top of that - this could possibly be related to perceivable absolute values (see "Psychoacoustics: Facts and Models").
The trouble is that it leads to some guesswork which, while looking educated, is in fact way off:
The error between guessed and measured value is the same magnitude as the error between guessed and anticipated value (for a link to a unit calculator between voltages and levels see my post #28 above).
Here's some proof of my claim about general lack of understanding:
gain said:
I don't believe you just give in, I believe you consider yourself the smarter one. Right?
Kidding!
Peace!
gain said:
You could. But this requires the receiving user to activate this option in the user's profile. And you didn't.
PS: Honestly, you should open up another thread. If only for posting a better suited thread title for the browse and search pages. And I promise to not throw any more unwanted measurements on you.
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