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setting gains

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=56358
Printed Date: May 10, 2025 at 2:50 AM


Topic: setting gains

Posted By: supradude
Subject: setting gains
Date Posted: May 24, 2005 at 5:23 PM

I know what the general rule is for doing this. I've done it this way lots of times. What do you do when you turn the gain all the way down on the amp and when you turn the volume 3/4 up on the HU the volume is already trying to distort? I had to turn the HU 2/3 up and then turn the gain up just barely and it sounds OK. Has anybody got a better way or is this normal? I've not had this happen before.

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'85 Toy



Replies:

Posted By: DYohn
Date Posted: May 24, 2005 at 5:50 PM
Sounds like either the HU is producing a really bad clipped signal, or the amplifier can't handle the voltage output from the HU.  This happens a lot when trying to use older amps with newer heads, or when using high-voltage heads with amops not designed for them.  What's the gear?

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Posted By: supradude
Date Posted: May 24, 2005 at 6:56 PM
I'll have to look up the model numbers on the 2. The HU is Pioneer. The amp is American Bass or something like that.

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'85 Toy




Posted By: haemphyst
Date Posted: May 24, 2005 at 11:43 PM
Sound like a little of both of what DYohn hit on. The Pioneer won't make a great big signal, and the swap-o-rama special American Bass probably doesn't like the signal the Pioneer IS capable of putting out...

This is what it sounds like to me...

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."




Posted By: supradude
Date Posted: May 25, 2005 at 8:21 AM
OK, Here are the model numbers. PioneerKEH-P424; American Pro Bass Machine VS-1405.

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'85 Toy




Posted By: DYohn
Date Posted: May 25, 2005 at 9:45 AM
Yes.  The Pioneer is most likely clipping, so 2/3 is probably the limit on that HU.  And yes, American Pro is simply flea-market junk.  No telling what input voltage it likes, and no telling if the unit you have works or not.  Oh, if you are using that amp to drive subs, make sure the load is no lower than 4 ohms; 8 ohms would be safer.  If you just bought it take it back as defective and get your money back.  If you must stay with that brand, keep swapping units, you might get lucky and find one that works well.  Sorry to say this, but it is simply the case with brands like that.

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Posted By: supradude
Date Posted: May 25, 2005 at 5:25 PM
So the HU is trash also? What is the best HU I can get? I want quality, but it doesn't have to be the very top of the line stuff. As for the amp, I picked it up to run mids and highs. I knew it was junk. I figured it would do for what I needed though. I seen a couple of people on here that recommended these amps. I have another one (Orion) that I can use in place of it. For the HU, what is the most important numbers to look at when selecting one? I use the Pioneer brand for the great radio reception they have. When buying another one I would like the tuner to be strong too. I had Alpine and the tuner was horrible on it.

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'85 Toy




Posted By: DYohn
Date Posted: May 25, 2005 at 5:43 PM

No, the Pioneer is not necessarily trash, it just apparently clips early.  Pioneer makes OK gear, but they are known for variable quality.  Not my favorite, but better than some other mainstream makes and yes they do tend to have excellent tuners.  An Orion amp should be far, far better than the AmPro. 

The most important numbers IMO when comparing head units are signal to noise ratio (S/N) which should be high, distortion (THD, IMD, etc.) which should be low, and frequency response which should be 20Hz to 20KHz.  Also important is what levels and frequencies those ratings are referenced to.  You want them all to be "0db" which means normallized in this case, and if the only numbers available are at "1Khz" beware, this is a common tactic for hiding crappy specs.  You want the rated distortion and S/N over the entire frequency spectrum. If you compare output voltage levels or output power levels, you want to compare the distortion level at rated output.  For example, 18 watts @ 0.1% THD will sound far, far better, cleaner and appear to be louder than a HU advertising 40 watt output @ 10%THD.



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