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RCA Output Voltage


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allmet33 
Copper - Posts: 112
Copper spacespace
Joined: March 02, 2005
Location: United States
Posted: October 25, 2006 at 1:47 PM / IP Logged  

What is the minimum amount of voltage that RCA's can put out without having to worry about distortion due to interference or the sound floor being raised?  I don't know if I'm asking this question the right way.  I spoke with an installer one time and mentioned something about increasing the voltage output on the RCA's going to the sub amp to eliminate distortion or interference.  What's the minimum voltage that can do this?

I think the best head unit out there has the pre-outs pushing 5 or 6 volts.  Most others range between 2 -4 volts.  I've seen sound processors that have an output of 8 volts, 11 volts...all the way up to 13.5 volts.

I have a Pioneer FH-P4200MP that's pushing 2 volts on the pre-outs.  What should I push the voltage up to for a clean signal?

'06 Hyundai Azera - Pioneer FH-P4200MP / Factory center channel & tweeters / Infinity Kappa 62.7i's; all 4 doors, 2 Phoenix Gold Xenon 10D2 10" subs pushed w/Phoenix Gold Xenon 600.1 amp
haemphyst 
Platinum - Posts: 5,052
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Joined: January 19, 2003
Location: Michigan, Bouvet Island
Posted: October 25, 2006 at 6:08 PM / IP Logged  
Don't worry about the pre-out voltage, and simply set the gains correctly for the amplifier on hand.
The more important spec on pre-out (IMO) is the output impedance - the lower the better. The output impedance is more important because it determines how much noise rejection the output devices are capable of maintaining (rather than noise masking, as a higher RCA voltage does).
The Pioneer head units (typically) offer neither high voltage OR low impedance outputs, this in addition to the noisy and relatively poorly designed ground plane within the units, makes them very susceptible to noise right off the bat. Proper HU grounding is VERY important with Pioneer heads. If really THAT worried about it, get a different (i.e. better) head unit.
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
allmet33 
Copper - Posts: 112
Copper spacespace
Joined: March 02, 2005
Location: United States
Posted: October 26, 2006 at 8:39 AM / IP Logged  

Haemphyst...

I understand what you're saying, but you still didn't answer the question I asked.  Changing the head unit is not an option as there aren't any others out there that will look right in my dash.  That being said, I have to work with what I have.

Why wouldn't I worry about the output voltage?

So far, that's two things that go against everything I've heard in the stereo world.  Wouldn't increasing the output voltage increase the efficiency of the signal, making less work on the amp?

By increasing the efficiency of the signal, wouldn't that decrease the chance of the noise being transferred to the amp?

The output voltage/impedence on my Pioneer head unit is 1.8V / 1K Ohm, what would be a better set up numbers to look for?

Sorry for all the questions, but they say if you wanna know...you gotta ask!  That being said, thank you for your time and consideration.

Mike

'06 Hyundai Azera - Pioneer FH-P4200MP / Factory center channel & tweeters / Infinity Kappa 62.7i's; all 4 doors, 2 Phoenix Gold Xenon 10D2 10" subs pushed w/Phoenix Gold Xenon 600.1 amp
haemphyst 
Platinum - Posts: 5,052
Platinum spaceThis member has been recognized as an authority in Electrical Theory. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spacespace
Joined: January 19, 2003
Location: Michigan, Bouvet Island
Posted: October 26, 2006 at 10:25 AM / IP Logged  
allmet33 wrote:
I understand what you're saying, but you still didn't answer the question I asked. Changing the head unit is not an option as there aren't any others out there that will look right in my dash. That being said, I have to work with what I have.
Understood, I was simply pointing out the design and characteristic design flaw of nearly all Pioneer head units.
allmet33 wrote:
Why wouldn't I worry about the output voltage?
Because your amp doesn't HAVE to have 8V to drive it to full output. The "gain control" is incorrectly called such. The gain of an amplifier is fixed, it is FAR more correctly labelled a level matching device. I can't recall the last time I saw any car amplifier that couldnt be driven to full output by (around) .2V
allmet33 wrote:
So far, that's two things that go against everything I've heard in the stereo world. Wouldn't increasing the output voltage increase the efficiency of the signal, making less work on the amp?
No. A fallacy. The amp will do the same amount of work, based on the OUTPUT power it is producing. It has NOTHING to do with the input signal level. As I stated before, the gain of an amplifier is fixed.
allmet33 wrote:
By increasing the efficiency of the signal, wouldn't that decrease the chance of the noise being transferred to the amp?
Again, there is no efficiency involved here. If there is noise, it will ALWAYS be there, until the source of the noise is removed or reduced. While it is true that a higher voltage MAY (or really, should help) help cover the noise, if you are getting noise levels that are high enough to intrude on 1.8V, increasing the voltage on the signal is putting a band-aid on a bullet wound. The other issues need to be fixed first, and a line driver is NOT the way to fix it. Additionally, EVERY amplifier will add noise and distortion to a signal, so it is best to use what you have, and optimize it, without adding additional gain stages.
allmet33 wrote:
The output voltage/impedence on my Pioneer head unit is 1.8V / 1K Ohm, what would be a better set up numbers to look for?
I remember Eclipse head units from a few years ago having 8v/4ohm (yes, 4 OHM) outputs. Their higher end units now have 8v/55ohm outputs. Your output impedance is 18 times higher than mine, meaning any noise that could get into your system must be about 6dB LOWER than anything getting into mine. That is a power factor of 4! The lower the output impedance on your RCAs, the better, and there is no exception to this rule, anywhere.
allmet33 wrote:
Sorry for all the questions, but they say if you wanna know...you gotta ask! That being said, thank you for your time and consideration.
Not any problem whatsoever, it's how we all learn! The only stupid question is the one that isn't asked!
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
allmet33 
Copper - Posts: 112
Copper spacespace
Joined: March 02, 2005
Location: United States
Posted: October 26, 2006 at 10:38 AM / IP Logged  

So basically, according to your intial reply...I need to make sure the head unit is grounded out really, really good?  What is the best way of assuring that?

Anything else I should know about the Pioneer head units???  I'm trying to get the best possible sound I can from my system.  Currently, I've got my sub amp running off the signal from the factory sub and I think that's pushing too much distortion to my sub and I fried it.  That is why I'm changing the head unit to an aftermarket so I can run a low level signal (RCA's) to the amp.

The amp is a Phoenix Gold Xenon 600.1(600 watts x 1 @ 1, 2 or 4 ohms).  So far, it's fried a PG Xenon 10D2 sub (450 watts), an Alpine Type-R (500 watts) and an Audiobahn Dub 1000 (600 watts). 

'06 Hyundai Azera - Pioneer FH-P4200MP / Factory center channel & tweeters / Infinity Kappa 62.7i's; all 4 doors, 2 Phoenix Gold Xenon 10D2 10" subs pushed w/Phoenix Gold Xenon 600.1 amp
haemphyst 
Platinum - Posts: 5,052
Platinum spaceThis member has been recognized as an authority in Electrical Theory. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spacespace
Joined: January 19, 2003
Location: Michigan, Bouvet Island
Posted: October 26, 2006 at 12:02 PM / IP Logged  
Not just the head unit, but a complete (if necessary) overhaul of your entire gounding system within the car.
I see nothing wrong with your amp, but:
1: PG woofer, overpowered by 33%, probably explains frying it.
2: Alpine woofer, overpowered by 25%, probably explains frying it.
3: Audiobahn woofer... the answer is in the question.
Look for a woofer that is HONESTLY rated at 600 watts, and then make certain your gains are set CORRECTLY. Distortion DOES NOT DESTROY WOOFERS, POWER DESTROYS WOOFERS. You are describing overpowering situations above. If you really LIKE to crank on it, and you do not know how to properly adjust your levels, then you need to set your sights higher - like a woofer that'll handle an honest 1500 watts, and you'll NEVER blow it again, using that amplifier.
It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
allmet33 
Copper - Posts: 112
Copper spacespace
Joined: March 02, 2005
Location: United States
Posted: October 26, 2006 at 12:14 PM / IP Logged  

Herein lies the problem.  I contacted PG AND Alpine and spoke to techs there, both assured me that their sub was VERY capable of handling the 600 watts my amp was producing.  I don't really crank my music constantly, but I do like to cut loose from time to time.  The PG tech actually recommended the 600.1 amp to push the 10D2 sub and that he's made that recommendation many, many times to others with no problems.

My understanding of using a sub that can handle 1500 watts on a 600 watt amp, then I'm grossly underpowering the sub and that can cause problems too, is that not true?

It's hard to know what to believe these days.  One reason I don't go along with the overpowering ideal is that I've seen for myself, an install that has a 10" DVC Memphis sub  (200 watts) being pushed by a Memphis amp producing 600 watts @ 2 ohms.  The sub was in a box just over a cubic foot, but it was handling the power with no problems at all.  The guy has an Alpine head unit (not sure which model) and he's using a Phoenix Gold Bass CUBE signal processor. 

My question is...why would his 200 watt sub be able to handle the 600 watts the amp is feeding it without frying if power fries subs???

It would seem to me that distortion would be one cause of a voicecoil frying if the distortion wasn't in the frequency range the voicecoil was designed to handle and if that distortion is being amplified to a certain point, then it stresses the voicecoil to failure.

The thing with using the gain control on the amp is there is no way to specifically tell if you've got the gain setting matched to the output voltage of the head unit.  It sure would be great if companies would put markings on the gain controls for the amps so we would know for sure!

'06 Hyundai Azera - Pioneer FH-P4200MP / Factory center channel & tweeters / Infinity Kappa 62.7i's; all 4 doors, 2 Phoenix Gold Xenon 10D2 10" subs pushed w/Phoenix Gold Xenon 600.1 amp
allmet33 
Copper - Posts: 112
Copper spacespace
Joined: March 02, 2005
Location: United States
Posted: October 26, 2006 at 12:20 PM / IP Logged  

Oh yeah...how do you know if any sub is "honestly" rated???

Let me repeat to you what the Alpine tech expained to me and the PG tech in a manner of words...

The Alpine sub is rated at 500 watts rms / 1500 watts peak.  He said, that being the case...you can power the sub with an up up to 1000 watts (with that being the beginning of the red zone leading to failure) and the sub will be fine.  When I told him I only had 600 watts, he was like, "Oh...you won't have any problems at all!"

'06 Hyundai Azera - Pioneer FH-P4200MP / Factory center channel & tweeters / Infinity Kappa 62.7i's; all 4 doors, 2 Phoenix Gold Xenon 10D2 10" subs pushed w/Phoenix Gold Xenon 600.1 amp
allmet33 
Copper - Posts: 112
Copper spacespace
Joined: March 02, 2005
Location: United States
Posted: October 26, 2006 at 3:31 PM / IP Logged  

So...without having equipment, what's the best way to set everything so that I don't run into this problem?  There are no markings to set the gain control by on the amp.

This also brings me back to me previous question...how can someone power a 200 watt sub with 600 watts and not fry the sub.  I mean...that's drastic overpowering by 400 watts.  And let me tell you, the bass hits like a monster (a single 10 in a sealed box). 

'06 Hyundai Azera - Pioneer FH-P4200MP / Factory center channel & tweeters / Infinity Kappa 62.7i's; all 4 doors, 2 Phoenix Gold Xenon 10D2 10" subs pushed w/Phoenix Gold Xenon 600.1 amp
vbel 
Copper - Posts: 246
Copper spacespace
Joined: July 15, 2004
Location: Canada
Posted: October 26, 2006 at 9:15 PM / IP Logged  
I have this same amp pushing a Polk Audio 10" in a sealed box. The sub is rated for 500 wrms. My gains are set at max, plus bass boost at +12db, EQ at the lower frequencies at around +3dB, and nothing failed after months of use. It also doesn't distort. Your cause of problem must be somewhere else.
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