Hello,
I'm trying to connect the Line Out of my iPhone directly into my car amp and add an in-line volume controller between the iPhone and amp. I had a couple of questions about that:
1) What pot value would be ideal?
2) Do I need a preamp stage?
Thanks!
I'm trying to connect the Line Out of my iPhone directly into my car amp and add an in-line volume controller between the iPhone and amp. I had a couple of questions about that:
1) What pot value would be ideal?
2) Do I need a preamp stage?
Thanks!
1) I wouldn't bother with a control, the iPhone has one.
2) No pre amp needed just a way of disconnecting the radio/cd/tape signal so not both are producing sound simultaneously.
2) No pre amp needed just a way of disconnecting the radio/cd/tape signal so not both are producing sound simultaneously.
Hello,
Thanks for the reply. Actually, the iPhone volume controls are bypassed when you use Line Out.
Thanks for the reply. Actually, the iPhone volume controls are bypassed when you use Line Out.
.
The fact that it's an iPhone doesn't really enter in. What you're talking about is feeding an amplifier from a headphone output. This is commonly done, it works fine, no biggee.
Of course what you don't want to do is damage your iPhone by overloading its headphone output. But by definition headphone outputs are low impedance--probably around 100 ohms--so all you have to do to be safe is feed a higher impedance.
How much higher? The posted circuit(s) shows a 50k (log) pot, but anything from 10k up will work fine.
The two circuits below are electrically the same. Just shown two different ways for, I hope, clarity.
Whether you'll need a preamp, well, unknown. But usually a circuit that will drive headphones will also drive an amp.
All of that said, nobody except Apple knows exactly what an iPhone's circuitry really is, so I have to weasel by saying no guarantees.
.
The fact that it's an iPhone doesn't really enter in. What you're talking about is feeding an amplifier from a headphone output. This is commonly done, it works fine, no biggee.
Of course what you don't want to do is damage your iPhone by overloading its headphone output. But by definition headphone outputs are low impedance--probably around 100 ohms--so all you have to do to be safe is feed a higher impedance.
How much higher? The posted circuit(s) shows a 50k (log) pot, but anything from 10k up will work fine.
The two circuits below are electrically the same. Just shown two different ways for, I hope, clarity.
Whether you'll need a preamp, well, unknown. But usually a circuit that will drive headphones will also drive an amp.
All of that said, nobody except Apple knows exactly what an iPhone's circuitry really is, so I have to weasel by saying no guarantees.
.
Attachments
That implies that the headphone amp is disconnected when the line out is used.
These outputs seem to be two different things.
Gajanan Phadte
does the iPhone detect that a receiver has been connected to the line out?
does it actually switch off the other output/s when a receiver is connected?
or only disable the digital volume control but still feed a signal to the other output/s?
I and probably others would need to know how the iPhone outputs signals before we can give sensible solutions.
does it actually switch off the other output/s when a receiver is connected?
or only disable the digital volume control but still feed a signal to the other output/s?
I and probably others would need to know how the iPhone outputs signals before we can give sensible solutions.
I don't understand why everyone keeps going back to headphone output. To be absolutely clear about this, I'm using the LINE OUT connection that you get when you use the 30-pin Line Out cable. NOT THE HEADPHONE OUTPUT.
Yes, I understand everything that you guys mentioned pertaining to the headphone output, and thank you very much for the input.
BUT I would like to know how to build the volume control whilst assuring impedance matching. I've already figured out the preamp stage, so that's all good.
Yes, I understand everything that you guys mentioned pertaining to the headphone output, and thank you very much for the input.
BUT I would like to know how to build the volume control whilst assuring impedance matching. I've already figured out the preamp stage, so that's all good.
My Android phone streams to the car radio using Bluetooth and does hands free calls too. I recommend you get a more modern radio. Mine plays MP3s off a 32G SDHC card too, or a USB stick, it was not an expensive radio.
You're hearing about headphone outputs because so many people make no distinction, they just say "output." They commonly mean a headphone output.
True, you did say line out, but broadly speaking line out is essentially a headphone output, so same difference.
Getting to your specific case you have...a what? A 30-pin line out? Jeeze, who knows how to connect to such a thing! Not me, for one.
Then why am I posting in the first place? Just to let you know that...
<< I would like to know how to build the volume control whilst assuring impedance matching >>
Impedance matching is for transmission lines and tube (valve) amplifiers. It's not how op amps (chip amps) work.
With op amps the rule is low feeds high. That is, you want a low impedance output feeding a high impedance input. The rule of thumb is x10, that is, input impedance should be approximately output impedance times 10 (or greater).
Happily, you already have this because all headphone and/or line outs are low impedance outputs, while essentially all op amps are high impedance inputs.
So nothing has changed, you still want line out feeding something like a 50k potentiometer.
That is...nothing has changed except for adding 29 pins. Lawsy! I'm thinking you might do better on a site specifically dedicated to iPhones? Or don't forget about YouTube, somebody has done almost everything there.
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This has told us nothing that helps you get the answers you need.
TELL US
what the 30pins give out.
SHOW us what your equipment can do and we can then advise.
If YOU buy Apple product that keeps everything secret then we can't help.
You have to break the code and give us a chance to help.
The iPhone's have a digital out that can go to a DAC, and if you're not doing that, I would use the headphone out since the quality is decent, and more than adequate for a moving car.
I have seen a hacker site that went over the details of getting the digital audio out without an apple licensed handshake from the receiving device.
I have seen a hacker site that went over the details of getting the digital audio out without an apple licensed handshake from the receiving device.
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