I Need a Low Impedance Head Unit, Please Clarify

[chee420]

Hello, I have a Hifonics Brutus 2600RMS monoblock and need to use a better deck than i have now, with a lower impedance.

I would like to know what full scale means when used in the user manual. It says Line-Out Level/ Subwoofer Out Level/ Impedance : 5.0V/20k ohm Load (full scale).

If anyone could tell me what full scale entails for Impedance it would be greatly appreciated.

Thanks

-Chelsea

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[chee420]

Would that deck be good, as i herd that low impedance is better.

What Head Unit would be best for the monoblock i have, and how drastic of a difference would one make compared to the other?

Kenwood KDC-X869

High Voltage Preamp Output: 5.0V

Low Output Impedance (80 Ohms)

Vs.

JVC KD-A805

Line-Out Level/ Subwoofer Out Level/ Impedance : 5.0V/20k ohm Load (full scale)

 

[JimJ 5,000+ posts]

Of all the things to worry about, this is something I wouldn't bother concerning yourself with.

Even if you had a significant impedance mismatch, it's a powered preamp stage...it's not like you're running a passive volume control and have to worry about cable capacitance //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[Rich B 5,000+ posts]

What Jim said.

If you're worried though, Eclipse is known to have some of the lowest output impedance in the business, but its not really worth buying an Eclipse over any other well known brand.

 

[thch 10+ year member]

so, digital recordings are essentially numbers. full scale refers to a test signal that spans all of these numbers. eg -- the loudest possible thing that could be recorded on a digital format*.

and this is the main point -- to map "maximum output" with some actual signal. full scale refers to what the loudest recording maps to in terms of preout signal level.

output impedance is a measure of an amplifier's ability to force a signal onto a line. it is more important when using multiple amplifiers, as at some point the HU's signal would start declining.

often output impedance is increased to allow for better driving of the cable for technical reasons. but there is still a goal to keep this value low.

the two listed specs are not the same. the first is saying the output impedance is 80 Ohm, while the second is saying that, if the HU drove and amplifier with a 20kOhm input impedance, the output would be 5.0V*.

it is somewhat hard to say what differences, if any, you will see. the parts in the amplifier that are inefficient are not related to the voltage gain, but rather in harnessing/controlling large amounts of current precisely to move the speaker exactly as the input signal dictates.

*the loudest "smooth" test signal that is.

 

[chee420]

so, digital recordings are essentially numbers. full scale refers to a test signal that spans all of these numbers. eg -- the loudest possible thing that could be recorded on a digital format*.
and this is the main point -- to map "maximum output" with some actual signal. full scale refers to what the loudest recording maps to in terms of preout signal level.

output impedance is a measure of an amplifier's ability to force a signal onto a line. it is more important when using multiple amplifiers, as at some point the HU's signal would start declining.

often output impedance is increased to allow for better driving of the cable for technical reasons. but there is still a goal to keep this value low.

the two listed specs are not the same. the first is saying the output impedance is 80 Ohm, while the second is saying that, if the HU drove and amplifier with a 20kOhm input impedance, the output would be 5.0V*.

it is somewhat hard to say what differences, if any, you will see. the parts in the amplifier that are inefficient are not related to the voltage gain, but rather in harnessing/controlling large amounts of current precisely to move the speaker exactly as the input signal dictates.

*the loudest "smooth" test signal that is.

Thank you for that response! Please make sure to clear up all of the further questions i have before the morning tomorrow if you can, (GMT -7:00) because we have our install schedualed for 3pm our time for the JVC deck.

A)How big of an improvement would the 5.0v JVC head unit make compared to my current Pioneer 2.2v 1k ohm, considering it is trying to power such a large amplifier? Is the 20k ohm of the JVC head unit also going to make a difference?

An installer we spoke to said when the voltages are up in the high impedance range they are not as good for sub woofer applications. I think he was trying to upsell us a discontinued kenwood deck with low impedance output that he mentioned to us over the phone.

So Basically i just want to know if this will help reduce the amount of gain i will have to ser my amplifier at, and if it will be an overall improvement in my system given the head unit we have currently?

B) Just want to clarify, we are getting a second Hifonics Brutus 2600 RMS and would like to know if the JVC head unit would still preform well powering 2 of those amplifiers?

Thank you again! And i look forward to reading the responses in the morning when i wake up.

-Chelsea

 

[bdawson72 5,000+ posts]

Oh snap we got a chick on our hands.

 

[bdawson72 5,000+ posts]

Waits for the sausagefest to ensue.

 

[JimJ 5,000+ posts]

A)How big of an improvement would the 5.0v JVC head unit make compared to my current Pioneer 2.2v 1k ohm, considering it is trying to power such a large amplifier? Is the 20k ohm of the JVC head unit also going to make a difference?

I wouldn't switch based on that alone; if the JVC had features you wanted that the Pioneer didn't, maybe.

An installer we spoke to said when the voltages are up in the high impedance range they are not as good for sub woofer applications. I think he was trying to upsell us a discontinued kenwood deck with low impedance output that he mentioned to us over the phone.

Sounds like you're right.

 

[mazdakid 5,000+ posts]

Knowledgesticks girlfriend?

 

[chee420]

yes i am //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif he refuses to come on thease boards anymore and we needed immiediete feedback, and the guys over at SMD where andrew asked, didnt quite know if it would make a big differance.

but i figure the guy wasjust trying to upsell us on low ohm impedance, because the one he wanted us to buy is discontinued now lol.

anyways can we stick to the point here, or is this going to turn into another troll fest?

 

[JimJ 5,000+ posts]

//content.invisioncic.com/y282845/emoticons/hilarious.gif.02a037aad04aa96f19982b298a3d70a8.gif :hilariou: //content.invisioncic.com/y282845/emoticons/hilarious.gif.02a037aad04aa96f19982b298a3d70a8.gif :hilariou: //content.invisioncic.com/y282845/emoticons/hilarious.gif.02a037aad04aa96f19982b298a3d70a8.gif

That's great.

and the guys over at SMD where andrew asked, didnt quite know if it would make a big differance.

Not very surprising, "impedance" is over two syllables; that may give them trouble.

 

[Immacomputer 10+ year member]

A)How big of an improvement would the 5.0v JVC head unit make compared to my current Pioneer 2.2v 1k ohm, considering it is trying to power such a large amplifier? Is the 20k ohm of the JVC head unit also going to make a difference?

There may be a difference but the line out impedance and voltage is not going to be the main culprit for the difference. Like Jim said, if the JVC unit has better features towards your needs, then it will more than likely be the better unit for your application. I went from an Eclipse 8445 unit with 8v 55ohm line outs to a JVC KD-AR8500 with the 5v 20k line outs and neither units have any difficulty with noise or driving large/multiple amps.

So Basically i just want to know if this will help reduce the amount of gain i will have to ser my amplifier at, and if it will be an overall improvement in my system given the head unit we have currently?

B) Just want to clarify, we are getting a second Hifonics Brutus 2600 RMS and would like to know if the JVC head unit would still preform well powering 2 of those amplifiers?

The higher preout voltage will allow you to set your gains lower to get the same output but difference is going to be minimal at best and there really won't be a large quality difference unless something is severely wrong with your current unit's line out. Again, there may be a difference in sound but it won't be due to the line out voltage or impedance.

And yes, the JVC will be fine running both amps as it's not the headunit that powers the amps -- it just supplies the input signal for the amp to follow; it is your electrical system that will power the amps to full gain.

That sales man is just trying to ditch a discontinued unit from specs he doesn't understand.

 

[thch 10+ year member]

again, the HU isn't powering anything. its merely providing instructions to the amplifier. the amplifier has several parts that prevent its output power from affecting how much current is drawn from the input. Further, the amplifier will be built to draw little current from the HU.

I will say that people tend to enjoy the higher preouts. that might be more due to these being placed on high-end HUs, or other reasons.

Keep in mind that just turning the HU volume down a bit will reduce the signal level significantly. so the "3/4ths max" might end up placing you below 2V. people tend to care about that spec more on paper.

the high output impedance can become an issue once you start powering multiple amplifiers.

edit -- previously you had listed the JVC as 80 Ohm output impedance. the 20kOhm likely refers to the average input impedance of an amplifier.

 

[chee420]

again, the HU isn't powering anything. its merely providing instructions to the amplifier. the amplifier has several parts that prevent its output power from affecting how much current is drawn from the input. Further, the amplifier will be built to draw little current from the HU.
I will say that people tend to enjoy the higher preouts. that might be more due to these being placed on high-end HUs, or other reasons.

Keep in mind that just turning the HU volume down a bit will reduce the signal level significantly. so the "3/4ths max" might end up placing you below 2V. people tend to care about that spec more on paper.

the high output impedance can become an issue once you start powering multiple amplifiers.

Our unit was sold to us from future shop , and it was on-sale i think it was the one that was one the wall too because they didnt have any of the ones in the box. We dont like having to set the level so high to get the propper voltage, the cleaner signal the better, and also with the ipod usb connection that will also reduce clipping, so it should provide a few nice upgrades.

we will update you guys when the new h/u goes in. It will help to have an actual ipod port on the front aswell since i have heard aux in can cause clipping because the ipod headphone-out creates clipping at 0db, but if you use the USB port, it doesnt. im not sure what that means just typing somthing i saw at another place