sonic impact t-amp in car?

[ractis]

Hi,

I'm thinking of using my sonic impact t-amp as a car amplifier.
Has any one tried it? I'm not sure if the input voltage from the car alternator would be too high for the sonic impact unit.

I'd appreciate any feedback/comments if you got the t-amp to work in your car, as well as if you needed any mods. If this works out well i'll probably swap it out for a chalize

Thanks in advance!

 

[DcibeL]

I'd definately put a regulator on the power line.

 

[Pano]

The Sonic Impact does not seem like a good choice for car audio. Just not enough power. You'd need very sensitive speakers and a very quiet car.

You might look at some of the Tripath based auto sound amps out there. E.G. the Blaupunkt.

 

[theAnonymous1]

I've used a T-amp in a car to power a 6.5" component set and it worked better than I had expected. There definitely wasn't ear piercing volume levels, but it was loud enough for casual listening. The amp was running straight off the alternators 14.2v and it never had any problems.

 

[peace brainerd]

Ha! Thank you ractis for providing one of those "I'll be damned" moments for me. Last night I was looking at the latest Partsexpress catalog and wondering why the sonicimpact amp isn't being used in a car. Hmm, a really execellent 12vdc amp for 130 bucks? It would seem natural for someone to think of this. 24 hours later your post pops up. Leave it to DiyAudio.

Car audio gets a pretty bad rep for generally esoteric reasons. It really is a $#!!TY environment for listening. Where else would anyone put up with such a laughable amount of ambient noise floor and unmanageable emi? But who won't admit that some of their finest musical moments have happened "behind the wheel"? It's a pretty funny thing actually. I think that more people in this hobby are closet road music aficionados than would be comfortable admitting.

C'mon
..Jean luc Ponty at speed, winding through a busy urban interchange, testing the perfect limit of fourth gear before this curve on a fine summer night?

..Wagner on a densely snowing wintry day along a beechnut lined country road in the rolling glacially-carved hinterlands of Michigan?

You know you've felt something like this

 

[ractis]

Thanks for all the replies so far!
Especially to anonymous1, you give me the courage to attempt to plug the SI t-amp in without adding a voltage regulator, lol

Bluebeard, I'm using the $29 t-amp, not the $130 version
If this works out well, we can probably hack together a very cheap but reasonable quality 4-channel car amp by getting 2 SI t-amps and placing the internals into a suitable casing.

 

[ractis]

I regret to report that my attempt to use the t-amp in my car failed.

Without the alternator running, the t-amp works rather ok, except for a very soft click that repeats about every 0.8 sec.

When the alternator is running, there is just mass distortion. I think the voltage must have gone too high.

My car is a Toyota Ractis. I simply tapped the power cable connected my in-dash receiver to power the t-amp. Is this okay?
Or perhaps I really need a voltage regulator?

Will appreciate any pointers on how I can make a easy voltage regular for the t-amp that makes it suitable to be usd in a motor vehicle. Thanks in advance!

 

[DcibeL]

regulator

Easily? Something like this IC should do the job. Put a large cap, say 1000uF or greater from input to ground, then a 10uF from input to ground and a 10uF from output to ground. It's not the easiest thing to just hook up in a car, but it would do the job.

I am not completely sure that the lack of a regulator is your problem, but it couldn't hurt.

 

[dnsey]

The Sonic Impact does not seem like a good choice for car audio. Just not enough power. You'd need very sensitive speakers and a very quiet car.

Power is of the same order as standard 'integrated' radios, which IMO is quite enough for ordinary purposes - I don't understand the fashion for high powered car audio, esdpecially as cars have become much quieter over the years.

Without the alternator running, the t-amp works rather ok, except for a very soft click that repeats about every 0.8 sec. When the alternator is running, there is just mass distortion.

Unlikely to be due to excessive voltage - it's probably just the very noisy supply which a car provides. A regulator will certainly help with this, but a choke / capacitor filter is really needed too - this is built into the design of dedicated car audio components.

 

[ractis]

Thanks for the ideas,

After some testing and research, I found that my problem is commonly called the 'alternator whine', a siren like noise in the signal that goes up in pitch when the alternator is spinning faster.

Sorry DcibeL. which IC are you talking about? The link you provided has expired. Would it work if I used a LM7812?
http://www.southwest.com.au/~jfuller/electronics/regulators.htm

Dnsey, I made the choke + capacitor filter but it had absolutely no effect on the alternator whine. I have no DIY knowledge so perhaps I built it wrong. I used a 330µF 16V electrolyte capacitor and a ring inductor that looks like a small toroidial transformer. Would that be fine?

I posted my problem in the car audio subforum as well, thanks for any more ideas.

(wondering if its because of the el cheapo interconnects I used. perhaps they are not even shielded? too tired to go to my car to test this now)

 

[DcibeL]

Sorry, Ractis. It was an LD1085V12. I figured at least a 2A supply is needed, so a 3A regulator should do the trick.

 

[dnsey]

I used a 330µF 16V electrolyte capacitor and a ring inductor that looks like a small toroidial transformer. Would that be fine?

You need a cap of about ten times that value (at least), and - if I understand you correctly - a much larger inductor. The secondary of an LT transformer would do for experimenting with.
Think of it this way - the frequencies that you're trying to supress are in the audio band, on a low impedence line, so you need a filter of the same order as a speaker crossover.

 

[theAnonymous1]

I've have quite a bit of experience dealing with auto sound and I would have to guess its a ground loop issue.

If your using your cars head unit to supply the audio signal, which I assume you are, make sure the head unit and the t-amp are powered from the same wires. More importantly, make sure the t-amps -12v connection is properly connected. If not, the t-amp will pull the -12v through the RCA ground, very bad.

I've tried my t-amp in about 3 different cars without the use of a regulator and haven't had any over voltage or noise issues.

 

[ractis]

I finally solved the problem by buying a $15 electronic noise filter and putting it before the power supply into the t-amp.

Thanks all for your suggestions!

PS. dnsey, I think you're right. The noise filter I bought is probably a choke/capacitor filter and it certainly feels 20x heavier than the ineffective one I built