Amplifier head room
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New member Username: HeadutterPost Number: 4 Registered: Jul-05 | I'm wondering how to get optimum clean sound out of my amps and speakers. As a sound engineer for live shows I always ran the gain on the amps at full out. This allowed me to have plenty of head room so the amp did not clip and the preamp could run at idle so as not to distort the signal going in. Is it the same for car audio amps? |
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Gold Member Username: James1115Wilton, Ct Post Number: 3555 Registered: Dec-04 | well with car audio you want to do more of matching to the speakers RMS power using the amp rms rating and the pre out voltage off your head unit. |
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Audioguy22 Unregistered guest | Not the same! with car amps running the inputs full will/could result in damage to your speaks, amp running hot and more THD. Over the years I'll start in the middle and most of the time I end up at the 1~2 o'clock position. As a rule I'll find out where my HU gets dirty(Volume # 31 on my Alpine) than set my amps in the middle,stick in a cd with the lowest levels I can find(pink floyd will work)and turn it up untill its too loud to handle. If I get anywhere near that 31 # I bring the gains up on the amps. My system's never sounded better than now! Alpine 9815 SoundStream VGA400.2 x2 Boston Pro 6.5 up front and a Boston Pro 10 in back. Compact truck 100% SQ(homie dont do beat) All off EBAY used for a grand total of $750.spipped! |
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New member Username: HeadutterPost Number: 5 Registered: Jul-05 | James, that's where the problem begins. This is going in a car that has a Bose/ Delco system. Circuit City taped off the rear sub with some kind of unit to take the speaker leads and run them to the amp. People have told me that's not the cleanest way to do it. Is there a better way? Matching the amps power to the power handling capability is the easy part. This is another reason why I thought keeping the gain down on the head was better and turning up the gain on the output of the amp was better. I also may be misinterpreting the use of terms for car audio. The gain control on the amp, as far as I know, controls the power of the amp, irrespective of the device used as a preamp. That is why when you turn it up, even with no device hooked up to it, you will hear an increasing hum. The preamp controls the input volume, thus s/n. Is that different on a car system? |
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New member Username: HeadutterPost Number: 6 Registered: Jul-05 | AudioGuy22, First thanks for the reply. I want to make sure I am understanding this. First I'm not talking about runnning the inputs full. That would be from the preamp signal and you are right that would clip the amp. I'm talking about running the output signal at full, then backing off on the input signal to make what goes in cleaner and what comes out cleaner. The restriction of the amp volume only causes you to increase the preampsignal to get more power, but your resticting it from going higher by not having the gain up. It would be like those games they have where you are attatched to a bungie and you try to run to the end. You can only go as far as the lenght of the cord. No matter how much energy you put in you can't get any more out because you've restricted the cord. What say you? Also, how would you compare the sound stream to anything else? |
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New member Username: Audioguy22Post Number: 8 Registered: Jul-05 | In car amps there are more than two stages. In home amps, there's an input stage and the output stage. some car amps have more than two. Also in home amps, as you increse your amps power rating you lose your upper end detail/air. Not an issue with car amps(because they never had it) so its wise to have a slightly bigger amp than needed to help with the high demand a car makes on the amp. If your speaker are rated at 60watts RMS and you run a 60watt rms amp, you'll never get a clean sound at 60 watts. If you run a 100watt rms amp, the output at 60watts would be very clean. With an over rated amp, you can set your input gain a little lower and never run the amp to full output. The result would be a cleaner system. Also, these adjustment screws control cheap little op-amps than sound really bad when worked to hard. |
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New member Username: Audioguy22Post Number: 9 Registered: Jul-05 | Since I was 17 I've used LinearPower amps(got my first installer job at the age of 15 around 1982)and they are truly badasz amps. A year or two back LP closed there doors for good. and I looked elsewhere for amps.after a long search and tryinglistening to many brands, I found an amp that blew the doors off the old LP's and has tons of power. The SS Van Gogh's are the sweetest amps for the money that I've ever heard. Just look at there beauty!!!  |
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New member Username: HeadutterPost Number: 7 Registered: Jul-05 | Benny Boy, as Paul Harvey would say, " and now you know the rest of the story " Or as Joe Pecce said in My Cousin Vinny, "I think I get the picture" That said, what do I get? Will a single sub, preferably a 12" in a ported cabinet, give me the pounding base. This is not competition, just 3 blocks away sound. Do I get one, say 1200 watt speaker or two 600 watts with the same 1200 watt amp? By the way why a dual voice coil as oppossed to one? Is the power split between them? Will a larger voice coil produce more punch? |
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New member Username: HeadutterPost Number: 8 Registered: Jul-05 | I'm checking out the Sound Streams right now! On their site there is no SS Van Gogh. Wher do I find it. How much power do they have and for what kind of money? |
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New member Username: Audioguy22Post Number: 10 Registered: Jul-05 | The VGA's were a limited run and are 04's Ebay is the place now. You can get the VGA600.2 for less than $200. than buy a 12" Titanic from : http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=295-404 It will play so loud, you'll need a barfbag! Just one of these will blow you away. I'm useing one in a 2qft box for home theater and it hits so hard with only 150 watt rms. If it would fit in my pu, I'd have one in there aswell. |
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Bronze Member Username: Audioguy22Post Number: 11 Registered: Jul-05 | Also, I just looked and PE still has there closeOuts. check these bad boys out!! http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=299-660 |
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Gold Member Username: Jonathan_fGA USA Post Number: 4236 Registered: May-04 | Gain must be set to match level with the head unit. It isn't a volume control, it is simply to for level matching to assure you don't overdrive the input stage of the amplifier. To set it correctly, an oscilloscope is ideal, second best is a voltmeter. If you have a scope, run a continuous 0dBfs tone from the head unit and view the waveform from the RCA outputs. Turn the volume up until clipping occurs, and take note where that occurs at. Some head units can run at full volume without clipping IF equalizers aren't boosted. That's something you need to verify with a scope, though. Once you've discovered that, take note of that and connect the RCAs to the amplifier. Do the same for the amp, view the waveform and adjust input level until clipping occurs, then back off until it stops. If you do this, you are pretty much guaranteed not to clip from overloaded inputs because CD Audio never exceeds the 0Db reference level. If you want to go a step further, keep the head unit at it's maximum clean output and use a preamp as a volume control. No matter what you do, maxing out the preamp volume will still provide a clean signal at the amplifiers. |
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