Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Preamp (or other solution) for connecting my Clip to my car line-in
New Posts  All Forums:Forum Nav:

Preamp (or other solution) for connecting my Clip to my car line-in

post #1 of 19
3/3/10 at 1:09pm
Thread Starter 
Hi all

This is my first message in this forum, since I live in the IEM forum mainly

I like to connect my Sansa Clip to my car stereo, which has a line in connector. The problem is that the sound output level of my Clip is very small so I have to turn up a lot both the Clip's volume and the car stereo volume. Not very practical...

I've thought about building a preamplifier, but I'm open to suggesions. In fact, I would prefer not to build anything (lack of time, mainly), so my question is:

- does a commercial (but cheap) product available?

if not:

- maybe a NE5532 based circuit will do?
- any other suggestion?

Oh, and no, using my FiiO does not suffice, it doesn't boost up the volume enough

Thanks in advance, dudes!
Reply
post #2 of 19
3/3/10 at 2:08pm
i don't really know about this stuff but wouldn't the car system already have an amp because it is presumably a power system? i know when i was using the line in connector from my fuze to caffeine amp to car system, the additional amping from the amp did not improve quality at all.

but is there any reason why you are opposed to just turning up the volume? imo, i would rather do that than lose sound quality..

but yeah, i really don't know enough to say - these are just my thoughts.. i don't really even know how a preamp differs from an amp but would assume there is a level of amping going on even in the preamp. please please correct me where i am mistaken.
Reply
post #3 of 19
3/3/10 at 2:23pm
Thread Starter 
Hi bik2101

First of all, thanks for your reply

I'll try to make things clearer, since my original post was a bit obscure, I'm afraid

Quote:
Originally Posted by bik2101 View Post
i don't really know about this stuff but wouldn't the car system already have an amp because it is presumably a power system?
Yep, the car system has an amplifier. The problem is that if you amplify a very very very tiny signal, you won't get a lot of output power, no matter the power capabilities of your amplifier. The signal coming from the headphone output of my clip is very small and low impedance, so it doesn't feed the car system properly.

Quote:
but is there any reason why you are opposed to just turning up the volume? imo, i would rather do that than lose sound quality..
Yes, I have a reason and it has nothing to do with sound quality (which is going to be pretty poor in my car, anyway). My reason is that in order to have a decent sound volume, the volume in the clip must be maximum (no problem with that, as long as I remember to put it down when plugging my IEM. That is: danger to my ears) and the volume in my car system has to be VERY high. This means that when I switch from the Clip to the FM radio of CD player (both on the car system), the sound level skyrockets It may even harm the speakers.

Quote:
i don't really even know how a preamp differs from an amp but would assume there is a level of amping going on even in the preamp. please please correct me where i am mistaken.
For this application you can think of the preamplifier as a small amplifier, with little power, enough to rise the output of the Clip to a proper level.

If you were to feed high impedance phones from a low output source, you would use a headamp. In this case, you can think that the car system is a "difficult to drive headphone" so in order to use my Clip I need a "special headamp": the preamp or even a small power amplifier.
Reply
post #4 of 19
3/3/10 at 3:22pm
Just use a CMoy I've built a couple Cmoy's for friends who had your exact same problem. They love them !

cheers!
Reply
post #5 of 19
3/3/10 at 3:40pm
yes, a cmoy is fine enough for a preamp.

be careful of alternator whine and ground loops. for a quick fix, if you run into hum, try a ground-loop isolator (transformer, really).

in fact, you could even find step-up transformers to give you voltage gain and get isolation at the same time (but the trafos that are audio quality may be expensive).

another option (pre-made) is a 'line amp' or balanced line driver. lots of car audio companies make this and its a simple gain stage but with a good dc-dc converter built in. zapco used to make things like that that were pretty good and audiocontrol, as well.
Reply
post #6 of 19
3/3/10 at 3:41pm
Yep, cmoy should be fine since you're just trying to increase the levels and don't have to worry about how well it drives a load.
Reply
post #7 of 19
3/3/10 at 6:15pm
Thread Starter 
Hi )

@the_equalizer and Juaquin: yes, I had thought about a CMoy, powered using the car 12V plus a 7808 or 7810 to do voltage regulation, but I wasn't sure about it since it is not going to be much cheaper than a preamp/low-power amplifier kit (as sold by Velleman et al.). But now that I think about it, it would be VERY funny to build a CMoy. Maybe I'll do, thanks

@linuxworks: I'll look for a line amp or balanced line driver. I don't know if they are going to be easy to find in Spain, or cheap enough. I have a DC-DC converter schematics somewhere, I designed one when I was at the university, but that was a century ago or so and I don't think I could design a new one from scratch XD. Maybe checking the internet... That would solve ground loops and alternator problems, of course, so it's a good solution no matter what I finally use (a preamp kit, a CMoy, etc.)
Thanks a lot from a now-very-short-haired-but-time-ago-a-long-haired-linux-geek
Reply
post #8 of 19
3/3/10 at 6:24pm
you COULD use 2 batteries and just recharge them. extra bonus points if you recharge them while the unit is off for the night (if you can do that safely).

no ground loops, no hum/noise, no dc/dc to care about.
Reply
post #9 of 19
3/3/10 at 6:51pm
Thread Starter 
Hi linuxworks

Quote:
Originally Posted by linuxworks View Post
you COULD use 2 batteries and just recharge them. extra bonus points if you recharge them while the unit is off for the night (if you can do that safely).

no ground loops, no hum/noise, no dc/dc to care about.
I want to avoid batteries because the amp (or cmoy, or whatever other solution) is going to be placed just behind the car stereo, where there's plenty of space... but it's difficult to access. I have to consider the price and complexity of building a dc-dc or buying a converter, and if I finally find all those options unbearably expensive or inconvenient, I'll install a battery holder in some accesible place and will cable it to the difficult to access spot.

Thanks
Reply
post #10 of 19
3/3/10 at 7:02pm
Quote:
Originally Posted by DervishD View Post
Hi linuxworks



I want to avoid batteries because the amp (or cmoy, or whatever other solution) is going to be placed just behind the car stereo, where there's plenty of space... but it's difficult to access.
<snip>
Ah! I think we've all been missing this crucial piece of information. Indeed the CMoy's I've built for car preamp duty are battery powered and are used within the car cabin, going to the car stereo aux input.

Well, building a CMoy with a 9 volt regulator should be simple and cheap enough, but as linuxworks points out, you'll need some filtering to stop the electromagnetic waves generated by the sparkplugs from entering the audio chain.

cheers!
Reply
post #11 of 19
3/3/10 at 7:03pm
cool.. thanks for clearing all that up.. learn something new everyday

Quote:
Originally Posted by DervishD View Post
Hi bik2101

First of all, thanks for your reply

I'll try to make things clearer, since my original post was a bit obscure, I'm afraid



Yep, the car system has an amplifier. The problem is that if you amplify a very very very tiny signal, you won't get a lot of output power, no matter the power capabilities of your amplifier. The signal coming from the headphone output of my clip is very small and low impedance, so it doesn't feed the car system properly.



Yes, I have a reason and it has nothing to do with sound quality (which is going to be pretty poor in my car, anyway). My reason is that in order to have a decent sound volume, the volume in the clip must be maximum (no problem with that, as long as I remember to put it down when plugging my IEM. That is: danger to my ears) and the volume in my car system has to be VERY high. This means that when I switch from the Clip to the FM radio of CD player (both on the car system), the sound level skyrockets It may even harm the speakers.



For this application you can think of the preamplifier as a small amplifier, with little power, enough to rise the output of the Clip to a proper level.

If you were to feed high impedance phones from a low output source, you would use a headamp. In this case, you can think that the car system is a "difficult to drive headphone" so in order to use my Clip I need a "special headamp": the preamp or even a small power amplifier.
Reply
post #12 of 19
3/3/10 at 9:39pm
if you have a relay circuit that goes on 'charge mode' when the car is off and 'run mode' when you turn the ACC to on, that might work. then you could bury all that behind the head unit.

to be honest, battery and charging is probably more trouble than its worth. if it was me, I'd probably just buy a thing like this:



I'm sure you can find 'line drivers' at your car audio stores. even though the unbalanced to balanced part isn't what you need, you can often get enough gain from them (or even modify them to increase a fixed amount of gain).

even things like this (I have one similar in my car, built into my dash):



so there's almost no need to build one; the brands have already done the good dc/dc conversion and all the rest.
Reply
post #13 of 19
3/4/10 at 5:27am
Thread Starter 
Hi the_equalizer

Quote:
Originally Posted by the_equalizer View Post
Ah! I think we've all been missing this crucial piece of information. Indeed the CMoy's I've built for car preamp duty are battery powered and are used within the car cabin, going to the car stereo aux input.
As I told, I may use batteries, putting them in some accesible place even though the CMoy will be in a hidden place.

Quote:
but as linuxworks points out, you'll need some filtering to stop the electromagnetic waves generated by the sparkplugs from entering the audio chain.
No sparkplugs in my engine It's a diesel engine, so the only electrical noise will be from the alternator.
Reply
post #14 of 19
3/4/10 at 5:30am
Thread Starter 
Quote:
Originally Posted by linuxworks View Post
if it was me, I'd probably just buy a thing like this:
I'll check my local car stores to see what they carry. Price is important, too, so maybe the CMoy or a preamp kit will be good enough.

Thanks for all your help, buddy )
Reply
post #15 of 19
3/4/10 at 6:35am
Be very careful powering a cmoy from the car power, when you plug into the stereo aux socket the virtual ground of the cmoy will be shorted to the cars earth which will usually be battery negative. this tends to liberate the smoke from the opamp, just once :-)
Reply
New Posts  All Forums:Forum Nav:
  Return Home
Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Preamp (or other solution) for connecting my Clip to my car line-in