Mobile Electronics Australia

MISTA_BISHI

Aug 23 2003, 01:26 AM

Hey just about to go to Jaycar tomorrow to get my RCA's and splitters and i was thinking does RCA splitters loose any sound quality via the use of these?? I wouldnt have a clue.

see yASS
Marc.

Marc

Aug 23 2003, 01:33 AM

I've never witnessed any audible loss when simply splitting to two sets.

How many are you splitting ?

MISTA_BISHI

Aug 23 2003, 02:17 AM

Wouldnt u like to know lol im not saying im disgrased at how many ill be using.

see yASS
Marc.

MISTA_BISHI

Aug 26 2003, 05:07 PM

So really is there any quality loss or voltage drop when using splitters??

Marc.

Bodyjar

Aug 26 2003, 05:33 PM

Well you're supposed to low half the voltage when you split once arent you?

Bassaholic

Aug 26 2003, 06:41 PM

It depends on the output impedance of the headunit and the input impedance of the amplifiers as well as the voltage.

Ie if you had one headunit with an output impedance of 500 ohms (Rhu) and an input impedance of 10k ohms (Ramp), as well as a preout voltage of 4v (Vi).

Vamp1 = Vi * Ramp / (Ramp + Rhu)

Vamp1 = 4 * 10000 / (10000 + 500)

Vamp1 = 4 * 0.952
Vamp1 = 3.8v

Say you then add an extra amplifier in parallel (using RCA splitters)

Vamp2 = 4 * (10000/2) / ((10000/2) + 500)
Vamp2 = 3.6v

The difference is 0.2v - only about 5%, so not significant.

Of course it starts to become a problem when the amplifiers input impedance nears the headunits output impedance.

Ie if you had 8 amplfiers, the input impedance would be 10000/8 = 1250

Vamp8= 4 * (10000/8) / ((10000/8) + 500)
Vamp8= 2.85v

But the other consideration, is this is assuming the headunit can output the extra current - if you drive too many amplifiers, the voltage may sag anyway, or you may even damage the headunit - this is especially the case when the input impedance drops lower than the output impedance.

The numbers used in the example, are just that - an example, so don't assume that you will only be able to drive 4 amps, or 32+++ etc without using the actual specs..

[ August 27, 2003, 15:25: Message edited by: Bassaholic ]

Mr_Bob

Aug 28 2003, 02:12 AM

i would have thought 500ohm was pretty high for most HU's.
my old RF was rated at 30ohm. and i think alot of Alpine HU's are rated at 50ohm..
or are these specs fudged too?

Bassaholic

Aug 27 2003, 05:37 PM

It varys. My headunit has an output impedance of 1000 ohms. (on the high side)

The trade off is preouts with a low impedance are more likely to get damaged - and I experienced just that twice with my last headunit. (actually, 2 of the same model)

I think most amps these days have an input impedance of 20k ohms.

Fudd

Aug 27 2003, 05:42 PM

QUOTE

Originally posted by Bassaholic:
It depends on the output impedance of the headunit and the input impedance of the amplifiers as well as the voltage.

Ie if you had one headunit with an output impedance of 500 ohms (Rhu) and an input impedance of 10k ohms (Ramp), as well as a preout voltage of 4v (Vi).

Vamp1 = Vi * Ramp / (Ramp + Rhu)

Vamp1 = 4 * 10000 / (10000 + 500)

Vamp1 = 4 * 0.952
Vamp1 = 3.8v

Say you then add an extra amplifier in parallel (using RCA splitters)

Vamp2 = 4 * (10000/2) / ((10000/2) + 500)
Vamp2 = 3.6v

The difference is 0.2v - only about 5%, so not significant.

Of course it starts to become a problem when the amplifiers input impedance nears the headunits output impedance.

Ie if you had 8 amplfiers, the input impedance would be 10000/8 = 1250

Vamp8= 4 * (10000/8) / ((10000/8) + 500)
Vamp8= 2.85v

But the other consideration, is this is assuming the headunit can output the extra current - if you drive too many amplifiers, the voltage may sag anyway, or you may even damage the headunit - this is especially the case when the input impedance drops lower than the output impedance.

The numbers used in the example, are just that - an example, so don't assume that you will only be able to drive 4 amps, or 32+++ etc without using the actual specs..

i knew that!!!!

i know ishould have listened at school]

MISTA_BISHI

Aug 28 2003, 01:11 AM

QUOTE

Originally posted by Bassaholic:
It depends on the output impedance of the headunit and the input impedance of the amplifiers as well as the voltage.

Ie if you had one headunit with an output impedance of 500 ohms (Rhu) and an input impedance of 10k ohms (Ramp), as well as a preout voltage of 4v (Vi).

Vamp1 = Vi * Ramp / (Ramp + Rhu)

Vamp1 = 4 * 10000 / (10000 + 500)

Vamp1 = 4 * 0.952
Vamp1 = 3.8v

Say you then add an extra amplifier in parallel (using RCA splitters)

Vamp2 = 4 * (10000/2) / ((10000/2) + 500)
Vamp2 = 3.6v

The difference is 0.2v - only about 5%, so not significant.

Of course it starts to become a problem when the amplifiers input impedance nears the headunits output impedance.

Ie if you had 8 amplfiers, the input impedance would be 10000/8 = 1250

Vamp8= 4 * (10000/8) / ((10000/8) + 500)
Vamp8= 2.85v

But the other consideration, is this is assuming the headunit can output the extra current - if you drive too many amplifiers, the voltage may sag anyway, or you may even damage the headunit - this is especially the case when the input impedance drops lower than the output impedance.

The numbers used in the example, are just that - an example, so don't assume that you will only be able to drive 4 amps, or 32+++ etc without using the actual specs..

Bassaholic, iam nothing but a mere mortal when it come to that kinda stuff dude is there any chance i could get the translated version to English (mildly retarded) version
cheers man
Marc

P.S I sat there for 15 minutes looking at it and for all i know it could be a recipe for a H Bomb lol

audible

Aug 28 2003, 07:49 PM

Good one Bassaholic you old doyen you!

The problem of splitting your rca's too many times was a problem back in my day, when all head units only put out 500mv from there rca out puts.

if you take bassaholic 8 amp example with a 500 mv head unit;

QUOTE

Ie if you had 8 amplfiers, the input impedance would be 10000/8 = 1250

Vamp8= 500mv * (10000/8) / ((10000/8) + 500)
Vamp8= 357mv

now that would be a huge problem. those old head units could rarely run more than 3 rca splits with out major drama's and the amps at the time didnt help either with limited input configorations.

my memories a bit vague, but i think these old decks had about 10k ohm impedance.