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Discussion Starter #1
Hello All,

Here is my intention, i have a 08 TSX with a HU that i will like to keep (has the a/c controls).

i want to replace the front speakers and add my own subs.

my plan is to use the HU > miniDSP> aftermarket 1sub+ 2 front component speakers.

the HU has 1v balanced pre-amp outputs to the factory amp. i will take that and run it into the miniDSP.

the miniDSP has 2v out max.

my amp (power acoustick PA4-800) states it has an input sensitivity of 0.2-1v.


will the miniDSP provide enough "juice" to drive my amp efficiently without the need for line drivers?


thank you in advance for any help provided!
 

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if you amp has a .2v - 1v setting and you hitting it with 2v. that will be more than enough. you will actually have to be carefull that you dont overdrive the input and clip it.

does it have a 1v - 10V setting as well?
 

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Discussion Starter #3
if you amp has a .2v - 1v setting and you hitting it with 2v. that will be more than enough. you will actually have to be carefull that you dont overdrive the input and clip it.

does it have a 1v - 10V setting as well?
wow! thank you for the near instantaneous reply!

no the amp does not have the 1v-10v settings.

it appears to be preety old. got it for $30 from a friend.
 

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ok, then if you turn the gain all the way down (1v setting) and then set your outputs on the minidsp for -2db, you should be golden.
 

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Discussion Starter #5
thank you.

another question...

how does one determine if the HU/pre-amp has sufficient ouput to power an amp?

is there a rule of thumb?

for example, i have a mono amp and i see it has 200mv-6v on the gain.

can u explain that?

would the dsp also be able to drive that?
 

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on that example, it means that you have a range of 200mV to 6V for the RCA inputs. if you set the amplifier for 200mV, then it will only take 200mV of signal to drive the amplifier to 100% output. if you set it to 6V, then it will take 6v of signal to drive the amplifier to 100%. (and obviously all points in between)

in that case, if the minidsp will supply 2v, then it will have enough signal to drive the amplifier, you just set it to 2V input. I dont know how technically savvy you are. but if you want to read this, it may explain (or confuse you more :) )

Setting gains.
 

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Discussion Starter #7
wow, that was a fantastic read!

you've been a great help .


i have been reading all day long for a week in regards to gains and pre-amps/amps, and this article was the one to actually answer the questions i have been looking for!


i consider myself preety tech savvy.lol
i can read/see something an understand it right away.
 

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thank you. been meaning to get around to some more write ups, but never seem to have time or motivation, lol.

if you have more questions, dont hesitate. :)
 

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Discussion Starter #9
that being the case, i have some more questions! lol

i have heard many people say that the 2v out (from various sources be it "low end
head-units, to the miniDSP or other pre-amps) is too low to drive "many" amps. and that they require line-drivers.

based on my understanding of the link you provided, it seems that they are not matching their sources correctly with the amps input sensitivity?

I further understand that the 'many" amps they may be using are more modern and require a higher voltage of input to drive it to 100% with the least distortion?

for example, the 6v-200mv of my mono-amp , from what i just learned, a 6v in from a HU will best drive this amp with the least distortion, vs my other amp with has a range of 0.2-1v .
where 1v will best drive this amp with the least distortion?


and to also confirm, the closer you get to the 200mv the more inefficient the amp becomes (inducing ground noises, alternator whine etc)?
 

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that being the case, i have some more questions! lol

i have heard many people say that the 2v out (from various sources be it "low end
head-units, to the miniDSP or other pre-amps) is too low to drive "many" amps. and that they require line-drivers.
"many" people dont have a great grasp on electronics and just submit to marketing hype ;) line drivers a rarely needed and ussualy add more noise to the system than anything else.
based on my understanding of the link you provided, it seems that they are not matching their sources correctly with the amps input sensitivity?
more than likely
I further understand that the 'many" amps they may be using are more modern and require a higher voltage of input to drive it to 100% with the least distortion?

for example, the 6v-200mv of my mono-amp , from what i just learned, a 6v in from a HU will best drive this amp with the least distortion, vs my other amp with has a range of 0.2-1v .
where 1v will best drive this amp with the least distortion?
the reason people like to have a higher voltage on the RCA lines is for noise rejection. if you have 1v of signal on your RCA lines and you have 0.25v of noise (from RFI, EMI, alternator, whatever), then 25% of your signal is noise. if you have 8v of signal and 0.25v of noise, then you have 3% of noise. might not even hear it. there is a valid reason to have a high output on the RCAs, with your minidsp, if you mount it close to the amplifier to keep the RCA runs short, it wont matter.
and to also confirm, the closer you get to the 200mv the more inefficient the amp becomes (inducing ground noises, alternator whine etc)?
nope, has nothing to do with efficiency. the closer you get to the 200mv setting on the amplifier the more gain you are asking the amplifier to produce. as with the above statement, if 25% of your signal is noise and you amplify that. then you amplify noise ;) also any internal noise in the input section of the amplifier will be amplified too. higher the gain, the more of this you will amplify.
 

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Discussion Starter #11
sweet. i'm absorbing everything you are saying! i'm loving it! lol

based on the above regarding the induction of noise into the lines, can you shed some light on what i "plan" to do?

the head-unit has balanced outputs, (3 wires per channel) @ 1v out.
the distance of the HU to the OEM amp is about ~9" ?

im planning to tap into just the front left and right outputs and send all 6 wires to the minidsp.
should i place the miniDSP in the trunk near my amps? (thereby extending 6 wires the length of the car) to reduce the induction of noise from the miniDsp to the amp?

or do you recommend installing miniDSP right next to the HU and then send the unbalanced output the amps.

Please note the miniDSP can accept balanced inputs and output in an unbalanced mode.
 

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sweet. i'm absorbing everything you are saying! i'm loving it! lol

based on the above regarding the induction of noise into the lines, can you shed some light on what i "plan" to do?

the head-unit has balanced outputs, (3 wires per channel) @ 1v out.
the distance of the HU to the OEM amp is about ~9" ?
nice, this will make it easier. since you are gonna route signals in a balance mode, then noise will not be of much concern, since common mode rejection is what balanced is all about. ;)

im planning to tap into just the front left and right outputs and send all 6 wires to the minidsp.
should i place the miniDSP in the trunk near my amps? (thereby extending 6 wires the length of the car) to reduce the induction of noise from the miniDsp to the amp?

or do you recommend installing miniDSP right next to the HU and then send the unbalanced output the amps.
I would run it balanced all the way back to the trunk where the other amplifiers are and keep the RCA runs short. cat6 cable works good for this. already twisted and designed to reject noise
Please note the miniDSP can accept balanced inputs and output in an unbalanced mode.
which one are you getting? 2x4, 2x8 or 8x8?
 

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Discussion Starter #13
use Ethernet cable you say!? i have TONS of ethernet cable laying around ! sweet

i will be getting the 2x4 with the 2.1 plugin.
 

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just dont leave any wires floating. either ground em or pull em out.

are you sure? I dont see a model of 2x4 that does both bal and unbal connections. they are either one of the other. the 2x8 or 8x8 will do what you are saying
 

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I would ask them how to wire it unbalanced on the output then, just to be safe. I suppose you could just wire 1 of the signal outputs and the ground to the RCAs.
 

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ok, you are good to go then.

RTFM get me everytime ;) (I never read the manual)
 

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Discussion Starter #19
lol yea, neither to i, i consider it extra/wasted packing .tehehe

but this time reading saved me from making a costly mistake.


question : u mentioned when using the Ethernet cable, u mentioned dont leave any wires loose/pull them out.

being that there are 4 pairs of wires in an Ethernet strand. can i wire 2 pairs to one of the 3 wires from the HU
and just use remaining pairs of wires for the rest?


please reference attached image.



Uploaded with ImageShack.us
 

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you can do it that way, but it would negate some of the twisted pair noise rejection.

I would wire it this way:



this is will also allow you to make an entire L/R run with one cat6 run
 
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