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Great job Erin. This will make for a great reference for understanding the problems with vehicle acoustics as well as ways to best work with the environment we're stuck with.

Might I suggest to also paste in some of your content from the sound power/power response 101 thread? Specifically the graphical representation of beaming and even sound power. Seeing a visual of 2 drivers playing (one with narrow response (beaming) and one with wide response is great. That was very helpful for me in understanding the concept and why it is so important in crossover selection in the vehicle.

I'm looking forward to further updates here. I know this is a laborious process, but your efforts are appreciated. Well done, sir !


-Steve
 

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Just checking, for gain settings instead of using a DMM (like you did) you could use an oscilloscope and -10db test tones looking for clipping (set gains just before that clipping point) from the beginning of the chain to the end of the chain (HU, DSP, Amps and whatever else is there with gain settings) through all devices. Correct? Do you see any drawbacks with that method?
 

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Discussion Starter #85
Most people don't have or have access to an oscope. Using it is fine.

I would suggest not setting your headunit level with the -10dB tone. Set it with 0dB. Most likely you'll max it out either way, but you want to start with the clean output you can. Adjust the things downstream of the headunit with an attenuated tone (-5dB or -10dB is typical).
 

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an odd question, but one that many people do have is about the maxing out of the deck's pre-amp.

conventional wisdom says that when you push a component to 100% of it's clean max, you're running it hot. You're making the most electrical juice go through the parts, you're pushing the deck's limit on capacity, and that is worrisome.

I understand that for S/N or dynamic range considerations, right before clipping should be where the best signal ends up at the amps.

But, how about just turning it back to 2/3 output?

Would it possibly contribute to a cooler running pre-amp, or give the deck more available power on it's power supply, for other circuits to run?

Is running a deck at 0 db, or max theoretical clean gain, somehow driving the deck too hard?

If it's just a matter of saying "the op-amps are designed to push all the way to the stops, so it doesn't matter how hard you crank a pre-amp" then that would be good to know, but if there's a chance that some of us are heating up our units unnecessarily, that would also be good to know.
 

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Discussion Starter #87
when you're talking about clipping, at the first instance, you're talking about THD+N values in the hundredths of a percent. maximize the source output up to that point (whether that be full pot or 2/3 pot or any arbitrary number that fits this conversation). then make up any lost volume via the attenuated tones.

that's how I do it. that's how others do it. that's not how everyone does it (whether on purpose or due to simply having no 'method' at all). I used to set gains based on audible noise floor. now that it's not a factor, I set them by a simple 3:1 power ratio.

YMMV.
 

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so the difference in longevity is nil?

you're saying that pushing a 4V deck to 4V as a normal tuning recommendation, is no different than pushing that deck to a max of 3V?

like, I understand that music is dynamic, and you rarely have a true 4V signal coming out of the deck for any duration, but in averaged power over time, would the deck that is averaging 1V be potentially less likely to fail over one that is pushing 2V?

always wondered that, as my non-scientific experience shows that a deck turned up real high, tends to heat up more, even if you can turn off the deck's speaker outputs, and especially if you can't, and even if they are not hooked to any load.

that's probably where the problem I think exists, in that when you turn the deck all the way to near-clipping levels, you may maximize the noise floor but you also may be shortening the life of the deck's output section, which is tied to the deck's pre-amp driving a set of op-amps that may or may not be happiest at higher voltage levels.


I usually equate power through components heating them up, as being a current issue, and in pre-amps the current is minimal, since we're dealing with high impedances.


but when you have a deck that is putting out it's high volt signal, at low ohm drive levels (a sign of quality in a deck) then maybe it matters?
 

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fair enough, then.

I know today's decks with DSP on board, should have slightly higher total current draw, based on the DSP's sucking of the power tap. That alone helps bring the heat into the deck chassis, and using one of these decks as a dead head, or no power out to speakers off internal amplification, is going to still bring up the average operating temperature compared to a non-DSP deck.

and one of the biggest issues facing DSP product is the temperature fluctuation in vehicles. You see DSP chips getting errors when you raise the temperature, and I think that a lot of problems come from the car environment making it harder for DSP architecture to operate in all temperatures and climates.
 

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so the difference in longevity is nil?

you're saying that pushing a 4V deck to 4V as a normal tuning recommendation, is no different than pushing that deck to a max of 3V?

like, I understand that music is dynamic, and you rarely have a true 4V signal coming out of the deck for any duration, but in averaged power over time, would the deck that is averaging 1V be potentially less likely to fail over one that is pushing 2V?

always wondered that, as my non-scientific experience shows that a deck turned up real high, tends to heat up more, even if you can turn off the deck's speaker outputs, and especially if you can't, and even if they are not hooked to any load.

that's probably where the problem I think exists, in that when you turn the deck all the way to near-clipping levels, you may maximize the noise floor but you also may be shortening the life of the deck's output section, which is tied to the deck's pre-amp driving a set of op-amps that may or may not be happiest at higher voltage levels.


I usually equate power through components heating them up, as being a current issue, and in pre-amps the current is minimal, since we're dealing with high impedances.


but when you have a deck that is putting out it's high volt signal, at low ohm drive levels (a sign of quality in a deck) then maybe it matters?
If you maximize the source output and set the gain with an attenuated tone (-5dB or -10dB), you'll be using less of your HU's pre-amp when playing your system at let's say 85dB of loudness
VS
Setting your HU down to 2/3 of its output and setting the amp gain to match the output voltage. Believe that your HU would (if it really does heat up) heat up more if you play it to 85dB of loudness

Am I wrong coz I'm not too sure after writting all of this lol

Kelvin
 

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Really loved the gain settings method you described here. I always tought setting gains was something you had to play with. Now I can match it perfectly with my HU. Thanks! :)
 

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If you maximize the source output and set the gain with an attenuated tone (-5dB or -10dB), you'll be using less of your HU's pre-amp when playing your system at let's say 85dB of loudness
VS
Setting your HU down to 2/3 of its output and setting the amp gain to match the output voltage. Believe that your HU would (if it really does heat up) heat up more if you play it to 85dB of loudness

Am I wrong coz I'm not too sure after writting all of this lol

Kelvin
I don't know.

I just know that when I crank the ol' decks to the stops, they did heat up, and I found that getting my deck to clip the amps at half-way on the knob, seemed to be a good setting, there was less heat noticed on the deck chassis.

Some of the newer decks with DSP probably do have ways to deal with heat, better than older decks on the average since DSP does take a small amount of power over the pre-amp or fluorescent lighting. Maybe the observation I make, is no longer valid?

I was asking, because I didn't know!
 

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Most people don't have or have access to an oscope. Using it is fine.

I would suggest not setting your headunit level with the -10dB tone. Set it with 0dB. Most likely you'll max it out either way, but you want to start with the clean output you can. Adjust the things downstream of the headunit with an attenuated tone (-5dB or -10dB is typical).
I see, thank you.
 

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Re: The Essentials of Sound Quality: Advice Based on My Trials and Tribulations

Time Alignment and Levels




Another way to consider it is going from this ...




... to this ...







Recap:

Remember, when adjusting levels and time delay what you’re adjusting with one speaker is RELATIVE to the other speakers. You’re adjusting the nearest speaker(s) so that it sounds as if it has the same intensity and time of arrival as the furthest speaker. This would then sound as if the other speaker had moved.

Or think of it like this: you’re moving your ‘center’ with respect to the left and right boundaries. You continue to do this until your boundaries sound equidistant from the center vocalist/pink noise.
I'm thinking this driver focused timing would destroy the experience for the passenger.... is there a way for both parties to share the widescreen? I feel like the passenger gets screwed over in this deal and ends up with the scattered images. Id like to impress as well as enjoy, is that out of the question?
 

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Re: The Essentials of Sound Quality: Advice Based on My Trials and Tribulations

I'm thinking this driver focused timing would destroy the experience for the passenger.... is there a way for both parties to share the widescreen? I feel like the passenger gets screwed over in this deal and ends up with the scattered images. Id like to impress as well as enjoy, is that out of the question?
You need to use a center channel and get some sort of center channel steering processing.

Kelvin
 

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Re: The Essentials of Sound Quality: Advice Based on My Trials and Tribulations

I'm thinking this driver focused timing would destroy the experience for the passenger.... is there a way for both parties to share the widescreen? I feel like the passenger gets screwed over in this deal and ends up with the scattered images. Id like to impress as well as enjoy, is that out of the question?

Do it with separate presets on the DSP ;)

You'll never get it to sound as good in BOTH seats as you can get it in a single seat.
 

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I'd guess it'd be like dialing in your TA and EQ to sound best dead center between driver and passenger. It'd be very likely a completely different tune with EQ as well as TA. Might possibly be an 'easier' tune though, as distances would be identical left/right as would 'theoretically' the EQ between left/right drivers. Steering wheel being the one thing asymmetrical really.
 
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