Dissappointed ... Need some settings help!

[tsenfw 10+ year member]

Just installed an an amp and 1 10" in a sealed box that I made. I'm kinda of dissappointed with the output. It will hit pretty decent if I turn it up but the gain has to be all the way up for where I want it at and I get some distortion (I think, kind of new to car audio).

Kenwood KDC-X791

-LPF at 100hz

-sub gain been experimenting between 3 to 7

-equalizer bass +2

-4 volt preamp out

Audiobahn ALUMN10Q (10")

-DVC

- 6 Ohm each coil wired parallel for 3 Ohm Load

-800 watt RMS (overrated I'm sure)

-1600 watt peak

Directed Audio D2400

-class d mono

-400 watt RMS @ 4 Ohm

-800 watt RMS @ 2 Ohm

-1200 watt RMS @ 1 Ohm

-LPF all the way up so the HU is in control

-Subsonic filter off

-Bass boost switched to highest setting of +6db

Please don't rag on my sub, I have a tight budget and inherited them. I saw a couple of good reviews of this budget amp, are they wrong? I have the gain at at least 75% and the settings turned up on the HU a little just to get it to sound right and at 100% gain for it too hit really loud (distorted). Is this common? Should my HU settings be at 0?

Could this because the amp is running under what the ratings say? I bought the amp refurbished and it looks in mint condition. I thought approx 600watts to a sub @ 3 Ohm would hit pretty hard.

Any help and suggestions would be appreciated!

Click to read more...

 

[Jekku 10+ year member]

First of all...

Set all eqs to flat, sub gain to max. Then read the sticky on amp setting or gain setting, no matter.

Then set the HU's LPF off or flat if capable, next set amp LPF roughly to 40-63Hz IMHO, best filter setting for sub is usually below 50Hz 'cos it's supposed to play bass frequencies below what your front stage is capable of. Do you follow?

 

[tsenfw 10+ year member]

Ok, I'll give that a shot. I read the stickies on gain setting. Seems like they discourage turning gain all the way to max because of distortion. I can't find a multlimeter that can handle the amps in a car so I've just been going by ear.

I'll change the LPF settings. I have a mustang with 6 X 8's all the way around. THey sucks! lol

 

[jco1385 5,000+ posts]

you need a multimeter that can do ~100v ac

edit. said 100a, meant 100v

 

[Jekku 10+ year member]

Ok, I'll give that a shot. I read the stickies on gain setting. Seems like they discourage turning gain all the way to max because of distortion. I can't find a multlimeter that can handle the amps in a car so I've just been going by ear.
I'll change the LPF settings. I have a mustang with 6 X 8's all the way around. THey sucks! lol

It's highly rare that the gains nowadays needs to be at the maximum level. That's because the HU's got high low-level outputs 2-4V. With gain all the way to max has bigger chances to overdrive the amp which will by time break.

You've got 6x8"? //content.invisioncic.com/y282845/emoticons/wow.gif.23d729408e9177caa2a0ed6a2ba6588e.gif You mean 6x9"? No matter.

I found that my old car which had 4x6" at front had better bass performance that my current cars 4". It maybe because 4x6" has bigger cone area than 4" does. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

And a answer to your first post; it actually doesn't matter what RMS wattage the sub can handle, because for normal listening you use about 100W at the time, or so I've heard.

 

[tsenfw 10+ year member]

So 2-4V preamp outputs are actually causing this? I though the higher the Voltage on the preamp output the better quality and strength signal for the amp to amplify?

Yes they are 6X8's. They are a common Ford sizing. 2 pioneer 3 ways and 2 kenwood 2 ways. They're ok but mid-bass kind of lacking.

So what is your suggestion? Turn up the sub gain on the HU and turn down the gain on the amp?

Or do I absolutely have to go get a multimeter to test this?

Maybe broken amp? It is a refurbished one. It still drives the sub mediocre.

 

[Jekku 10+ year member]

So 2-4V preamp outputs are actually causing this? I though the higher the Voltage on the preamp output the better quality and strength signal for the amp to amplify?
Yes they are 6X8's. They are a common Ford sizing. 2 pioneer 3 ways and 2 kenwood 2 ways. They're ok but mid-bass kind of lacking.

So what is your suggestion? Turn up the sub gain on the HU and turn down the gain on the amp?

Or do I absolutely have to go get a multimeter to test this?

Maybe broken amp? It is a refurbished one. It still drives the sub mediocre.

No, preamp outs are not causing this. Thing that's causing it is overdriving your amp with highly clipped signal. Higher the voltage on preamp outs equals better SQ and easier for the amp to compensate the signal without overdriving, as in gain is set at minimum or near minimum.

What's your HPF Hz for the 6x8s? If it's higher than 80Hz or near 80Hz I'd suggest lowering it to 50-60Hz.

And yes, set the sub gain on the HU to max, that'll be easier for the amp and less likely to get overdriven.

No, you don't need a dmm to set the gains if you don't want to. The best way to set gains is an Oscilloscope or your ears. If you intend to use your ears, beware, it's really painful when you set your front/rear speakers with 1kHz sinewave. Really...//content.invisioncic.com/y282845/emoticons/crazy.gif.c13912c32de98515d3142759a824dae7.gif

But in your case, buy a dmm with true rms ac voltage capability. I did and I'm happy. No, I don't have a Fluke, I've got a cheaper model with tRMS capability. Actually it wasn't the most expensive model they had but the second. Dude, I'm writing a book here. //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

 

[tsenfw 10+ year member]

Good, write more! It's very helpful lol.

I'll try those settings and see if I can get the gain on the amp down.

Thanks!

 

[Jekku 10+ year member]

No problem. Glad to help you.

 

[goodstuff 10+ year member]

No, preamp outs are not causing this. Thing that's causing it is overdriving your amp with highly clipped signal. Higher the voltage on preamp outs equals better SQ and easier for the amp to compensate the signal without overdriving, as in gain is set at minimum or near minimum.
What's your HPF Hz for the 6x8s? If it's higher than 80Hz or near 80Hz I'd suggest lowering it to 50-60Hz.

And yes, set the sub gain on the HU to max, that'll be easier for the amp and less likely to get overdriven.

No, you don't need a dmm to set the gains if you don't want to. The best way to set gains is an Oscilloscope or your ears. If you intend to use your ears, beware, it's really painful when you set your front/rear speakers with 1kHz sinewave. Really...//content.invisioncic.com/y282845/emoticons/crazy.gif.c13912c32de98515d3142759a824dae7.gif

But in your case, buy a dmm with true rms ac voltage capability. I did and I'm happy. No, I don't have a Fluke, I've got a cheaper model with tRMS capability. Actually it wasn't the most expensive model they had but the second. Dude, I'm writing a book here. //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

No offense, I don't know how they do it in finland, but your really gonna **** this kids shit up if you think the gain should be automatically cranked. If you set it with a sine wave you want to use a dmm, if your going to set it by ear why the **** wouldn't you just use music?

 

[DejaWiz 5,000+ posts]

If you need more reference to setting gains, click the link in my sig. And one should never, never play test tones through speakers.

 

[jco1385 5,000+ posts]

since we're on the topic, ho would i set the gains on my 4ch if i bridge it to 2ch. i want to run it at 160wrms x2 @4ohms. i have a dmm, but where do i find test tones? how to use them to set gains? never done it like this.

 

[DejaWiz 5,000+ posts]

1. since we're on the topic, ho would i set the gains on my 4ch if i bridge it to 2ch? i want to run it at 160wrms x2 @4ohms.

2. i have a dmm, but where do i find test tones? how to use them to set gains?

never done it like this.

1. Use the formula SQRT(Watts*Ohms) = Amp Output Voltage

SQRT(160*4) = 25.3V from each bridged output.
 
2. Get the wav versions from the download section at http://www.realmofexcursion.com

 

[jco1385 5,000+ posts]

thats exactly how i just did it. i got 25.29v

link maybe??

also, how do i know what voltage is clipping?

 

[Jekku 10+ year member]

If you need more reference to setting gains, click the link in my sig. And one should never, never play test tones through speakers.

You're correct my friend.