What is meant, by a 4volt Preout? What is a Preout? How does an increase in Volts for a Preout make a difference?
An explanation would be awesome.
Replies (7)
swez on 11/21/2007 12:05:47
Preout's are basically tiny power amps that generate a given voltage range to outboard amlpifiers further down the chain.
Most quality HU's have 2 kinds of amplifier circuits inside. One set of amps are designed to driver speakers as the load. In most cases, we are talking 10-22 watts RMS of power into a 4 ohm speaker load.
The preout amps are low voltage and feed the input side of an outboard amplifier. The input load will vary from amp to amp maker, but 10,000 ohms is a typical load value for the amplifier input side. (Some higher, some lower)
Voltage ratings for preouts for Consumer level prodcuts can be very subjective and not well regulated like Pro Audio gear. A Consumer level product can claim 4 volts or higher if they wish, but at what load value?
FYI: Have seen some HU makers claim 4.0 volts at 55 ohms. But if the amp load is 1000 or more, the voltage numbers at the preouts are much less. That's fine if the HU and amp used are from the same maker and paired to fit just so.
The last part of this equation is the gain control feature on a given amplifier. This helps the user match the preout voltage of any given HU to drive any given amplifier full output capability. That range is often 1/4 volts to 4.0 volts. (Some amps can even do higher than 4 volts)
No matter, the goal here is to get enough clean audio signal from the source unit, back to the amplifier input to overcome noise that is common to all Mobile audio installs. (That's a very long subject of discussion and we'll not go there for now)
Hope that helps,
Swez
gsandha99 on 11/21/2007 13:07:38
Through what medium are these volts being sent to the amp?
Is it through the RCA's?
And if so, if one of the RCA cables is broken, and i am only using, say, the right channel, am i limiting my pre out voltage from 4volts to 2 volts?
As explained in my previous thread, one of my RCA's broke and ive used a Y connector on the remaining good RCA to split it in two and plug those into the amp.
cplkittle on 11/22/2007 02:09:02
Preout voltage is generally rated per channel. (front left 4v, front right 4v, rear left 4v, rear right 4v, left sub 4v, right sub 4v).
By using a y to split one 4v channel, you will get 2v on each side of the y.
swez on 11/22/2007 09:18:12
Quote: "Through what medium are these volts being sent to the amp?
Is it through the RCA's?"
That would be a Yes
Repairing the damaged RCA wire is easy with the proper tools, a good RCA plug and the ability to get at it w/o removing the whole line from the vehicle. That's your best option other than ripping the whole line out and replacing it w/ a brand new line.
Swez
Ash on 11/23/2007 08:21:54
The voltage output on the rca is variable like the wattage on a amp.
You will not get the full voltage unless the HU is driven considerably high. Just like the wattage on a amp, rca's have peaks and continuous.
Example:
Most lower line Pioneer HU's state a 2 volt rca output. When measured at medium volume they barely hang around 1 volt. At almost full volume with music, on some sort of meter you will see peaks around 2. Mainly with loud passages and bass peaks.
It would be natural to assume when they get their reading at the manufacturer, they are using probably some pink noise or other nonmusic source for testing.
Like Swez stated, this doesn't matter much, as long as you get a good clean signal adequate enough to keep amp gains down a bit. Still higher volts is better...
cybersailor420 on 12/3/2007 00:14:28
Hi all. sorry i have been a bit MIA. new job is tedious...
anywho, just wanted to chime in real quick. i've been catching up on all the posts.
i just wanted to comment on cplkittle's post above. not to knit-pick, but voltage does not split in parallel, only current does. so by using a y-splitter, each channel should still see 4 volts, but the current will be halved to each side.
correct me if i'm wrong...
-Ian-
swez on 12/3/2007 02:10:42
That is correct. On a parallel circuit, the voltage to all devices is the same, but the current to each device changes with the resistive part of each tap in a parallel line.
Swez
An explanation would be awesome.
Replies (7)
swez on 11/21/2007 12:05:47
Preout's are basically tiny power amps that generate a given voltage range to outboard amlpifiers further down the chain.
Most quality HU's have 2 kinds of amplifier circuits inside. One set of amps are designed to driver speakers as the load. In most cases, we are talking 10-22 watts RMS of power into a 4 ohm speaker load.
The preout amps are low voltage and feed the input side of an outboard amplifier. The input load will vary from amp to amp maker, but 10,000 ohms is a typical load value for the amplifier input side. (Some higher, some lower)
Voltage ratings for preouts for Consumer level prodcuts can be very subjective and not well regulated like Pro Audio gear. A Consumer level product can claim 4 volts or higher if they wish, but at what load value?
FYI: Have seen some HU makers claim 4.0 volts at 55 ohms. But if the amp load is 1000 or more, the voltage numbers at the preouts are much less. That's fine if the HU and amp used are from the same maker and paired to fit just so.
The last part of this equation is the gain control feature on a given amplifier. This helps the user match the preout voltage of any given HU to drive any given amplifier full output capability. That range is often 1/4 volts to 4.0 volts. (Some amps can even do higher than 4 volts)
No matter, the goal here is to get enough clean audio signal from the source unit, back to the amplifier input to overcome noise that is common to all Mobile audio installs. (That's a very long subject of discussion and we'll not go there for now)
Hope that helps,
Swez
gsandha99 on 11/21/2007 13:07:38
Through what medium are these volts being sent to the amp?
Is it through the RCA's?
And if so, if one of the RCA cables is broken, and i am only using, say, the right channel, am i limiting my pre out voltage from 4volts to 2 volts?
As explained in my previous thread, one of my RCA's broke and ive used a Y connector on the remaining good RCA to split it in two and plug those into the amp.
cplkittle on 11/22/2007 02:09:02
Preout voltage is generally rated per channel. (front left 4v, front right 4v, rear left 4v, rear right 4v, left sub 4v, right sub 4v).
By using a y to split one 4v channel, you will get 2v on each side of the y.
swez on 11/22/2007 09:18:12
Quote: "Through what medium are these volts being sent to the amp?
Is it through the RCA's?"
That would be a Yes
Repairing the damaged RCA wire is easy with the proper tools, a good RCA plug and the ability to get at it w/o removing the whole line from the vehicle. That's your best option other than ripping the whole line out and replacing it w/ a brand new line.
Swez
Ash on 11/23/2007 08:21:54
The voltage output on the rca is variable like the wattage on a amp.
You will not get the full voltage unless the HU is driven considerably high. Just like the wattage on a amp, rca's have peaks and continuous.
Example:
Most lower line Pioneer HU's state a 2 volt rca output. When measured at medium volume they barely hang around 1 volt. At almost full volume with music, on some sort of meter you will see peaks around 2. Mainly with loud passages and bass peaks.
It would be natural to assume when they get their reading at the manufacturer, they are using probably some pink noise or other nonmusic source for testing.
Like Swez stated, this doesn't matter much, as long as you get a good clean signal adequate enough to keep amp gains down a bit. Still higher volts is better...
cybersailor420 on 12/3/2007 00:14:28
Hi all. sorry i have been a bit MIA. new job is tedious...
anywho, just wanted to chime in real quick. i've been catching up on all the posts.
i just wanted to comment on cplkittle's post above. not to knit-pick, but voltage does not split in parallel, only current does. so by using a y-splitter, each channel should still see 4 volts, but the current will be halved to each side.
correct me if i'm wrong...
-Ian-
swez on 12/3/2007 02:10:42
That is correct. On a parallel circuit, the voltage to all devices is the same, but the current to each device changes with the resistive part of each tap in a parallel line.
Swez
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