DiyMobileAudio.com Car Stereo Forum banner
1 - 20 of 27 Posts

·
Registered
Joined
·
20 Posts
Discussion Starter · #1 ·
I am trying to put both a Precision Power i1000.1 mono amp and a miniDSP C-DSP 6x8 in my car and I have three questions, all equally important, regardless of length.

1. Could someone please explain what equipment I need to power both of these devices simultaneously from my battery? Like what kind of power wires, power distribution blocks, ground wires, fuses?

2. Can I put the amp in the spare tire well under my hatchback trunk? This is a 2019 Subaru Crosstrek. I figured the compartment under the trunk of a hatchback is probably no hotter than most regular cars’ trunks and people put amps in their trunks all the time, right? Am I wrong about something?

3. I will do just about anything to avoid setting this sub amp's gain by ear. I've done this once before with a different amp, and when I did, I thought I was going to blow my ears out. So I put on ear protection and still felt like I was going to damage my subwoofer and disturb the peace. It's hard to find a place to do this where people aren't going to give me funny looks. Using my own ears also just doesn't seem like the most accurate way to set the gain. I do own a voltmeter and know how to use it. I just couldn't use it that time because the amp was built into the sub.

This time, however, the amp and sub are separate, and I'd really love to set the gain on this amp without using my ears but I'm a bit confused since I will be using the speaker level inputs on the PP amp. The manual for the PP amp says that you should turn the gain knob to match the input voltage. The lowest gain setting is for 6 V. The highest gain setting is for 0.25 V. It was my understanding that amps with speaker level inputs convert it back to line level before amplifying it. If I'm not wrong about that, I don't know where to set the gain because I don't know what the voltage will be once it's converted by the amp. If I am mistaken, that is, if the amp actually just amplifies the speaker level signal as is, then I also have no idea where to set the gain, since speaker level going into it is way more than 6 V, right?

I figured if I could find what the recommended output voltage is of this amplifier, I could just measure the output with the voltmeter and aim for that. Unfortunately, I can't seem to find that recommended output voltage. Is the recommended output voltage calculable from the rated RMS power? Electricity is not my forte.
 

·
Registered
Joined
·
9,259 Posts
I am trying to put both a Precision Power i1000.1 mono amp and a miniDSP C-DSP 6x8 in my car and I have three questions, all equally important, regardless of length.

1. Could someone please explain what equipment I need to power both of these devices simultaneously from my battery? Like what kind of power wires, power distribution blocks, ground wires, fuses?

2. Can I put the amp in the spare tire well under my hatchback trunk? This is a 2019 Subaru Crosstrek. I figured the compartment under the trunk of a hatchback is probably no hotter than most regular cars’ trunks and people put amps in their trunks all the time, right? Am I wrong about something?

3. I will do just about anything to avoid setting this sub amp's gain by ear. I've done this once before with a different amp, and when I did, I thought I was going to blow my ears out. So I put on ear protection and still felt like I was going to damage my subwoofer and disturb the peace. It's hard to find a place to do this where people aren't going to give me funny looks. Using my own ears also just doesn't seem like the most accurate way to set the gain. I do own a voltmeter and know how to use it. I just couldn't use it that time because the amp was built into the sub.

This time, however, the amp and sub are separate, and I'd really love to set the gain on this amp without using my ears but I'm a bit confused since I will be using the speaker level inputs on the PP amp. The manual for the PP amp says that you should turn the gain knob to match the input voltage. The lowest gain setting is for 6 V. The highest gain setting is for 0.25 V. It was my understanding that amps with speaker level inputs convert it back to line level before amplifying it. If I'm not wrong about that, I don't know where to set the gain because I don't know what the voltage will be once it's converted by the amp. If I am mistaken, that is, if the amp actually just amplifies the speaker level signal as is, then I also have no idea where to set the gain, since speaker level going into it is way more than 6 V, right?

I figured if I could find what the recommended output voltage is of this amplifier, I could just measure the output with the voltmeter and aim for that. Unfortunately, I can't seem to find that recommended output voltage. Is the recommended output voltage calculable from the rated RMS power? Electricity is not my forte.

1. You need your power, ground, RCA's and remote turn on wires for the amp. Will you be adding a fullrange amp for your front speakers? You'll need a fuse holder with an appropriately sized fuse near the battery. The size of wire and fuse will depend on whether or not you will be running a second amp. You can tap into this with your DSP wires if you want, otherwise you can pull power from the head unit, or just about any other switched source.

2. There will be A LOT more heat under the cover. The problem isn't the ambient temperature from the air, the problem is that the amp will be generating it's own heat, and it will be trapped without ventilation.

3. Setting gains by ear is my prefered way, and the way I encourage people to do it. The problem you had before could have been solved by just turning the gains down, it's that simple.
 

·
Registered
Joined
·
8,886 Posts
1. You need an amp wiring kit, they are sell them at almost every car audio shop and every online location. Personally i like KNu Conceptz.
2. You can, but you may find the need to add a fan to pull the warm air out of the space if the amps get too hot.
3. Spend some time researching more about setting gains by ear. There is nothing about that process that should blow your ear drums.
 

·
Registered
Joined
·
20 Posts
Discussion Starter · #6 ·
Hi, @miniSQ , funny running into you again.

Thank you for your advice.

3. Spend some time researching more about setting gains by ear. There is nothing about that process that should blow your ear drums.
Here was my process:
I had the HU's volume at 3/4 of max, which is an estimate of where HUs start to clip.
I started with the sub gain all the way down and played a 50 Hz sine wave at 0dBFS through the system and turned it up until I heard distortion/overtones, then backed it down until I didn't.
I took a photo of the gain knob in this position for my own reference. This told me highest value I could set my gain safely. Later I turned down the gain a bit to balance the sub with the rest of the system.

Turning up the subwoofer gain to the point of clipping while the HU was 75% maxed out was insanely loud. Please let me know if I'm doing anything wrong.

The problem you had before could have been solved by just turning the gains down, it's that simple.
But I would literally never listen to my music anywhere near 75% of my HU volume. That's so high. In my current car, I'm averaging about 18% of my HU's volume. For very quiet songs, I've had to turn it up to just above 30%. If I were to set my gain so that the bass didn't hurt my ears at 75% volume, it wouldn't be nearly loud enough at the 18% volume that I normally listen to music.
 

·
Registered
Joined
·
8,886 Posts
Hi, @miniSQ , funny running into you again.

Thank you for your advice.



Here was my process:
I had the HU's volume at 3/4 of max, which is an estimate of where HUs start to clip.
I started with the sub gain all the way down and played a 50 Hz sine wave at 0dBFS through the system and turned it up until I heard distortion/overtones, then backed it down until I didn't.
I took a photo of the gain knob in this position for my own reference. This told me highest value I could set my gain safely. Later I turned down the gain a bit to balance the sub with the rest of the system.

Turning up the subwoofer gain to the point of clipping while the HU was 75% maxed out was insanely loud. Please let me know if I'm doing anything wrong.



But I would literally never listen to my music anywhere near 75% of my HU volume. That's so high. In my current car, I'm averaging about 18% of my HU's volume. For very quiet songs, I've had to turn it up to just above 30%. If I were to set my gain so that the bass didn't hurt my ears at 75% volume, it wouldn't be nearly loud enough at the 18% volume that I normally listen to music.
set the gains on the REST of your speakers by ear, and then turn the gain of the sub amp up to balance the sub against the rest of the system at a reasonable level.
 

·
Registered
Joined
·
20 Posts
Discussion Starter · #8 ·
set the gains on the REST of your speakers by ear, and then turn the gain of the sub amp up to balance the sub against the rest of the system at a reasonable level.
But wouldn't setting the gains on the rest of the speakers hurt even more because I'd have to use higher test tones?
 

·
Registered
Joined
·
8,886 Posts
But wouldn't setting the gains on the rest of the speakers hurt even more because I'd have to use higher test tones?
No, you can do it while playing music. Google might be your friend here, lots of youtube videos on how to set gains by ear. Its not complicated LOL.
 

·
Registered
Joined
·
20 Posts
Discussion Starter · #10 ·
Music or test tones, I'd still be driving these speakers to the point of obvious distortion, which is going to be loud. The distortion of music is even less obvious than test tones because there's so many harmonics and distortion in music itself. Then, it's obviously going to matter what music you're playing. Some songs will have bigger dynamics with a higher risk of clipping at my comfortable listening level. Some songs will have more of certain frequencies than others. It just seems like a very bad approximation. On the other hand, with a 0 dbFS sine wave, you know it's an objective worst case scenario.
 

·
Registered
Joined
·
8,886 Posts
Music or test tones, I'd still be driving these speakers to the point of obvious distortion, which is going to be loud. The distortion of music is even less obvious than test tones because there's so many harmonics and distortion in music itself. Then, it's obviously going to matter what music you're playing. Some songs will have bigger dynamics with a higher risk of clipping at my comfortable listening level. Some songs will have more of certain frequencies than others. It just seems like a very bad approximation. On the other hand, with a 0 dbFS sine wave, you know it's an objective worst case scenario.
whatever....if you can't wrap your head around what i am saying, do it with test tones and a DMM and disconnect the speakers.
 

·
Registered
Joined
·
20 Posts
Discussion Starter · #12 ·
whatever....if you can't wrap your head around what i am saying, do it with test tones and a DMM and disconnect the speakers.
Which is exactly what I did the last time I had to set gains on a car audio system. Then I moved to the setting the subwoofer gain, which I was forced to do by ear since the amp was built into the sub. And doing this was very, very loud, as I mentioned above.
 

·
Registered
Joined
·
9,259 Posts
Your gains should be set so that your using most of the head unit's volume range. If you're reaching very loud levels at 18-30% of your range, your gains are too high. Your quietest recordings should require most of the full unclipped level of your head unit for enthusiastic levels.
 

·
Registered
Joined
·
20 Posts
Discussion Starter · #14 ·
Sorry @miniSQ I forgot you said
then turn the gain of the sub amp up to balance the sub against the rest of the system
Still, how would I know that the level I select is safe? It's also nice to be able to reference the maximum optimal gain in case I need to increase the gain after say, an EQ change, and know I can do so without risking clipping the frequencies that I didn't attenuate.
 

·
Registered
Joined
·
9,259 Posts
If you can't hear the clipping while listening for it, it won't hurt anything. Play your quietest music, for me it's probably some of my Simon and Garfunkel stuff. With the gains low, set the head unit to about 75% of it's max range, turn up the gain until the music reaches enthusiastic levels, or you hear distortion, whichever comes first. Back the gain off a tad, and you're done.
 

·
Registered
Joined
·
20 Posts
Discussion Starter · #16 · (Edited)
Your gains should be set so that your using most of the head unit's volume range. If you're reaching very loud levels at 18-30% of your range, your gains are too high. Your quietest recordings should require most of the full unclipped level of your head unit for enthusiastic levels.
Just for the record, it's not VERY loud at 18%. Just loud enough for my taste. Although most songs at 30% I would definitely call loud. This is the factory amplifier and this is the way it is configured by default by the way. However, I wouldn't want to turn the factory amp down since the amp has a built in safety EQ that kicks in harder the more you turn up the volume. Plus I'm not even sure if the gain on the factory amp can be manually changed since it's a factory amp.
 

·
Registered
2018 F150
Joined
·
249 Posts
Disconnect the speakers

Hook your multimeter to the speaker output terminals.

Play a test CD at max head unit volume

Adjust the amp gain until AC reading on the voltmeter hits 42.5 volts.

The 42.5 is just for this amp, assuming you have a 2 ohm sub.

V= square root of (900 watts x speaker resistance).
 

·
Registered
Joined
·
20 Posts
Discussion Starter · #18 ·
@GoldRiver That is very helpful. Thank you. Yes, it is a 2-ohm sub. It's this one, specifically. I assume it's probably safe to set the HU volume at 75% of max while doing this, right? I'm never going to reach that level, anyways, so I certainly won't ever reach max HU volume.
 

·
Registered
Joined
·
9,259 Posts
If you aren't going to mess with the factory amp (if it's even possible), then just adjust the sub amp gain to balance the sound. I don't see the problem.
 

·
Registered
Joined
·
8,886 Posts
If you aren't going to mess with the factory amp (if it's even possible), then just adjust the sub amp gain to balance the sound. I don't see the problem.
trying to convince people that setting gains is not rocket science ( and should not hurt your ears) can wear one out LOL.
 
1 - 20 of 27 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top