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Car audio folk: Can I put an amplifier with speaker level inputs after a low power factory amp? Login/Join 
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Picture of Black92LX
posted
The Tundra has the JBL system which is just alright. It’s integration makes pretty much swapping things out an all or nothing kind of thing. So to do it right looking at $2500-$3000. It’s also not set very well to do things in stages.
The worst part of the system is without a doubt the bass.
The factory amp to the subwoofer is supposedly like 55 watts RMS at 2 ohms.
I sound deadened the cab (still need to do the doors) and swapped an Alpine 8” sub into the JBL housing to replace the factory paper sub.
This cleaned and tightened up the base substantially. Though did not really add bass. I listen to all sorts of music types and utilize different sources so I am constantly jockeying the bass level which can be a number of button pushes away.
I don’t have the coin to swap the entire system as I would like and it will probably be quite sometime before I can.

Can I buy an amp like the Audio Control ACM-1.300 that has speaker levels inputs and just plug the current sub wires into it and then feed the Alpine sub with the proper wattage?
https://www.crutchfield.com/p_...ntrol-ACM-1-300.html

The Audio Control amp is rated at 300 watts RMS at 2 ohms and so is the Alpine sub.
It will also allow me to have direct control of the bass through a bass knob instead of trying to go into the settings on the head unit.

I understand this is a bit of a round about way of doing things?
Granted I would have to run power for the amp from the battery and ground it to the chassis as well.


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Posts: 25354 | Registered: September 06, 2003Reply With QuoteReport This Post
Unflappable Enginerd
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In theory, you'd turn down the input gain to balance the sound, which it appears to mention in their manual.

My guess is you'll have to do a bit of a balancing act with your front end bass level (lower) and that gain control(low to mid setting) to make it work correctly.


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Posts: 6192 | Location: Headland, AL | Registered: April 19, 2006Reply With QuoteReport This Post
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That’ll work.
 
Posts: 10823 | Location: SWFL | Registered: October 10, 2007Reply With QuoteReport This Post
quarter MOA visionary
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Yes it will work albeit low level output on radio to low level on the amp would be better and less noise.
 
Posts: 22858 | Location: Houston, TX | Registered: June 11, 2006Reply With QuoteReport This Post
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It should work fine.
Edit: Scratch that, it's 600W@2ohm, need my eyes checked I guess.
Are you set on that amp? There's a mono alpine for $220 that caught my eye after following your link.
Alpine
Nothing wrong with the audio control that I can see, but I like matching gear, especially at a lower price. It's 350W, but that is nothing.

Just don't crank the gain up until it clips. I ran a 400W amp on a 250W rated sub for 10 years in the last truck. O-scope said it was running 350-375W with a 1khz sine wave playing at 'I can't stand it without earplugs' volume, and gain could go up without clipping. "headroom" on amps is a good thing. It probably never hit that much on music. Wish I had kept the amp, it was a beast for as cheap as it was.

If you were going to replace the Mid/high speakers & do the same thing, I'd suggest a processor to take the high-level input, reprocess/EQ/etc and then feed the amps a low-level, EQ'd output. OEM headunits are tuned to all the components in the system, it can sound like shit with certain changes. The guy that bought the truck unhooked the fosgate 360.2 that was in it & fried it - he called me to ask about it & said it sounded 'screetchy' after he bypassed the processor. I had everything above 15khz turned WAY down from the stock headunit.
 
Posts: 3297 | Location: IN | Registered: January 12, 2007Reply With QuoteReport This Post
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I am not sure that will get you clearer bass. The problem might be that there is no base coming out of the factory Amp. If that is the case you can't amplify a signal that isn't there. Before attempting that Google for some test audio signals in 20Hz to 100Hz range and playback on stereo and see if you can hear anything. If you hear it but it isn't as loud as you want then it should work.
 
Posts: 1359 | Location: Colorado | Registered: May 28, 2010Reply With QuoteReport This Post
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I looked at the actual specs on the Audio Control amp, which you can see here:

https://www.audiocontrol.com/c...amplifiers/acm-1300/

It can handle speaker level input up to 40 volts, so you should be fine. If you want to test it, play a 50 hz tone on the head unit (phone apps or download an mp3), and measure the output voltage from the factory amp to the factory sub. This would be A/C voltage, as music is A/C.

My guess is that the JBL system is feeding that sub somewhere around 6-10 volts. If you don't have a meter or don't want to go to the trouble, I am highly confident that it doesn't come close to the 40 volt input capability of that amp.

For educational purposes, I can tell you that most amplifiers cannot handle anywhere near 40 volts input.
 
Posts: 3425 | Location: Baton Rouge, Louisiana | Registered: June 20, 2006Reply With QuoteReport This Post
Don't Panic
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This is tingling a long-lost memory of '70s era discussions of audio techniques.

I am pretty sure back in the day it was not considered best practice to daisy-chain power amps. Not sure what the technical/electrical circuit issues were, but I do dimly recall there were said to be audio quality repercussions. Phase shift, maybe? Impedance mismatch of amp 1's output with amp 2's characteristics?

Maybe I'm mistaken, and/or maybe with modern amp designs the chaining of power amp to power amp has no issues.
 
Posts: 15001 | Location: North Carolina | Registered: October 15, 2007Reply With QuoteReport This Post
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quote:
Originally posted by joel9507:
This is tingling a long-lost memory of '70s era discussions of audio techniques.

I am pretty sure back in the day it was not considered best practice to daisy-chain power amps. Not sure what the technical/electrical circuit issues were, but I do dimly recall there were said to be audio quality repercussions. Phase shift, maybe? Impedance mismatch of amp 1's output with amp 2's characteristics?

Maybe I'm mistaken, and/or maybe with modern amp designs the chaining of power amp to power amp has no issues.


Using an already amplified signal as an input isn't ideal. When you amplify, you distort the signal slightly - better amps distort less, but it's always there. If you amplify it again, you amplify the distortion + add more. For this application (sub on factory stereo), it's not going to be a big deal & the alternative (replace a shit ton of factory components) isn't really a better alternative. It's a helluva lot easier to splice into 2 or 4 speaker wires than to rip out the integrated radios in today's vehicles. The days of "do you need a DIN or Double-DIN adapter?" are gone.

Amplifier distortion isn't really a big deal for everyday audio systems, especially in a car (noisy) environment - it's one of those #s on a spec sheet that everybody argues about, but nobody can tell a difference between 0.05% & 0.1% THD@1khz except for those with golden ears. You are more likely to have trouble with replacing factory systems in the Mid/High ranges where the OEM gear has been tuned for the specific car environment - that's where a signal processor taking the amplified signal & Re-EQing/time alignment/etc can help.
 
Posts: 3297 | Location: IN | Registered: January 12, 2007Reply With QuoteReport This Post
quarter MOA visionary
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quote:
Originally posted by joel9507:
This is tingling a long-lost memory of '70s era discussions of audio techniques.

I am pretty sure back in the day it was not considered best practice to daisy-chain power amps.

Not sure what the technical/electrical circuit issues were ...


The issue is quality, compatibility and performance.
Namely the amp INPUT has a range of accepted output from the source.
If not in range it will distort or worse and in any case the power is not cumulative of the amps but only the power rating of the end amp to the speaker is used.
Now days the input for high level (speaker) can accept a wide range but it is better to just use low level inputs and low level outputs from the source (usually the car deck itself) and bypassing going through an amplifier section and getting whatever distortion/noise it may have.
Use high level inputs only in a last resort scenario.
 
Posts: 22858 | Location: Houston, TX | Registered: June 11, 2006Reply With QuoteReport This Post
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