Laptop Audio to Amp

August 18, 2011 12:56 AM

Hand-me-down electronics mix and match: laptop audio through amp?

I have a c. 1994 Denon tuner/amplifier which still works fine. I use it in my shop, along with the ultra-fancy five-CD carousel I bought back then, too, which, miraculously, still works.

What I'd like to do is run audio out of my "shop special" T60 Thinkpad into the amp, so I can listen to MP3s while wrenching.

I have plenty of inputs on the back of the amp, and I have a cable which I plug into the headphone jack of the laptop, which then splits into channels and is connected to the "aux" input on the back of the amp (I chose "aux" randomly, lots of choices: phono, tape, etc.).

Problem is, as you might expect, it sounds like total crap. I suspect this is because the headphone output is amplified, but "suspect" exhausts my "knowledge". Volume settings don't seem to do much to fix this.

Is there a different way or a trick to get audio out of my laptop , into my amp, and have it sound halfway decent?

I'd be willing to spend a bit of money if I need a special cable or a cheap card I can find on eBay or something. The laptop is docked and running win7, if it matters.

Note, I'm not really excited at the idea of buying an MP3 player or another device to do this; my laptop connects to my server and I have my MP3s stashed there, since I am not a portable music guy.

posted by maxwelton to computers & internet (11 answers total)

"Aux" should work; if not, try "tape". "phono" has a built-in EQ curve to compensate for the way the record is pressed; you're definitely going to get something different plugging into that one.

what kind of connectors are on the aux in? when you plug in the cd carousel, what inputs do you use for that?

What does "sounds like total crap" mean: distorted? really small and tinny like a telephone?
posted by dubold at 1:53 AM on August 18, 2011

you could also try to balance out the volume setting on your laptop and your amp. Try keeping the laptop volume under 50% and then adjust the amp volume and test, test, test. You may have the laptop volume set too high.
posted by alchemist at 2:24 AM on August 18, 2011

what kind of connectors are on the aux in? when you plug in the cd carousel, what inputs do you use for that?

You need minijack (3.5mm) on the laptop side and 2x RCA (Phono) on the amp side. I think it is possible to wedge minijack into a phono socket iirr so just checking.

Problem is, as you might expect, it sounds like total crap. I suspect this is because the headphone output is amplified, but "suspect" exhausts my "knowledge"

It should sound OK to take it from the headphone socket. Check the gain structure: Turn up the volume high on your music software, then turn the volume low on the amplifier and increase it until the volume is ok. This will make sure that you're not boosting a low signal with the amplifier and also boosting the noise.

If that doesn't work, then you'll have to track down what's wrong. Post details. If the output is bad on the lappie, then maybe a cheap soundcard could help but don't buy if it's not the problem.

On preview, afaik the volume on the laptop should be high as long as it's not clipping. You want to increase the volume in the digital software so you don't have to boost it in the analogue amp too much.

However, it might be worth checking the settings for the audio on the laptop. Is there driver software that's doing something odd?
posted by Not Supplied at 2:28 AM on August 18, 2011

alchemist has a good suggestion with the volume. Basically the way to troubleshoot audio stuff is to switch out or otherwise isolate components in order to figure out the problem.

So, in order from source to speaker, something like:

• Does turning laptop volume help? Does the laptop sound okay if you listen to it with headphones? If not, something is wrong with your laptop sound card or audio jack or something.
• Can you plug something else into the audio cable you're using? (Borrow an mp3 player or use the headphone jack of your CD changer?) Does it also sound terrible? You need a different cable.

Etc. This sounds basic and common sense but it works really well and when I don't do it I almost always regret it.
posted by joshuaconner at 2:34 AM on August 18, 2011

A lot of times laptop outputs are just sound crappy. In my experience you can hear noises caused by the hard drive or moving the mouse. If your hearing a 60hz hum you have a ground loop which can be fixed with a transformer or by the slightly less safe method of lifting the ground with a 3 to 2 pin adapter on you laptop's power cord. Most laptop sound cards are pretty crappy you can buy a cheap USB sound card that may fix your problems. If you could better explain what "sounds like crap" is we could give you a more definitive answer.
posted by jmsta at 3:31 AM on August 18, 2011 [1 favorite]

Ah, technical details!

I do have a cable as described by Not Supplied.

"Crap" means heavily distorted, mainly. It ends up sounding like a bad car radio powering bad car speakers turned up too high: total mud.

The laptop dock only has a two-prong outlet (not grounded) as does the amplifier.

I'll do some experimenting with volumes tomorrow, but I swear I tried all combos of laptop volume/amplifier volume, but I may have been negligent.
posted by maxwelton at 4:29 AM on August 18, 2011

I think it's worth trying a simple USB sound card or "DAC". You can build one easily if you can solder, for example the AlienDac (link is to a kit).
posted by krilli at 4:49 AM on August 18, 2011

If you're hearing distortion, it's possible you're overloading the aux input with laptop volume. This happens a little bit with my macbook volume up all the way, running into my 70's solid-state receiver. I've found having the mac volume set around halfway works just fine.

Try the tape in, with the same settings. If all inputs are equally distorted, turn down the laptop volume.
posted by dubold at 8:00 AM on August 18, 2011

hmmm...check the equalizer in the music program your using, if it sounds muddy, it might be set to "small laptop speakers with no bass" as opposed to "kick-ass stereo"
posted by sexyrobot at 8:30 AM on August 18, 2011

ERROR 823: OPERATOR IS IGNORANT.

I did not have this plugged into "aux." I had it plugged into "phono," which, as dubold noted above, isn't going to work too well. Just tried a test MP3 and it sounded fine.

Many thanks for all the ideas!
posted by maxwelton at 2:12 PM on August 18, 2011

(Best answers for everyone for trying to solve a non-existent problem.)
posted by maxwelton at 2:13 PM on August 18, 2011