Menu
Forum
General Car Audio
Subwoofers
Speakers
Amplifiers
Head Units
Car Audio Build Logs
Wiring, Electrical and Installation
Enclosure Design & Construction
Car Audio Classifieds
Home Audio
Off-topic Discussion
The Lounge
What's new
Search forums
Gallery
New media
New comments
Search media
Members
Registered members
Current visitors
Classifieds Member Feedback
SHOP
Shop Head Units
Shop Amplifiers
Shop Speakers
Shop Subwoofers
Shop eBay Car Audio
Log in / Register
Forum
Search
Search titles and first posts only
Search titles only
Search titles and first posts only
Search titles only
Log in / Join
What’s new
Search
Search titles and first posts only
Search titles only
Search titles and first posts only
Search titles only
General Car Audio
Subwoofers
Speakers
Amplifiers
Head Units
Car Audio Build Logs
Wiring, Electrical and Installation
Enclosure Design & Construction
Car Audio Classifieds
Home Audio
Off-topic Discussion
The Lounge
What's new
Search forums
Menu
Reply to thread
Forum
Car Audio Discussion
Head Units
HU Pre outs
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Message
<blockquote data-quote="HCCA" data-source="post: 2297995" data-attributes="member: 571196"><p>Sorry, so very wrong! The lower output impedance, and the higher the output voltage, the better the induced noise rejection. If you want to keep alternator whine, static hiss, humm, etc, out of the signal path, you have to keep the output impedance as low as possible, and the output voltage high. 4 volts is sufficient, but it serves a hidden purpose. All 12 volt decks without a switching power supply derive their output voltage from converting 12 volt DC line in, to 2V, or less output AC signal. Without a switching power supply, you cannot gain any more output voltage. It's not possible. What's more, you will have clipping at the higher volume settings. Something you want to avoid in the setting of all other components in your system. However, unlike your other components, you cannot adjust the I/O gains to get rid of the clipping.</p><p></p><p>A switching power supply, if done right, can give you 4,5, in the case of some Sony units, 8v of output. This is clean, undistorted, non-clipped signal. It is the same concept as what your amp's power supply does. Brings in 12v DC, and after switching it to pulsed DC, rectifying it, and running it through a transformer, the voltage is stepped up to somethin like 24-36 volts. So, the output voltage aside...the clean non-clipped signal output you get from a switching power supply is all the reason you need to look at higer output voltages. Also, if you have an output impedance that is too high, say 2000 ohms, you must look at the input impedance of the next downstream device (say...an EQ). It must then have an input impedance of 10 times that amount, to drive it. That would be 20,000 ohms. Some devices don't have that kind of input impedance. With an output impedance of your HU (60 ohms), you can drive anything with an input impedance of 600 ohms or more. A zero ohm impedance would, theoretically, drive ANY input impedance device.</p><p></p><p>As another note, you cannot induce a voltage across a dead short, right? Well, zero impedance at the output of a head unit is essentially a dead short (as far as radiated noise is concerned). As output impedance drops, it becomes more difficult for radiated noise to enter the system.</p></blockquote><p></p>
[QUOTE="HCCA, post: 2297995, member: 571196"] Sorry, so very wrong! The lower output impedance, and the higher the output voltage, the better the induced noise rejection. If you want to keep alternator whine, static hiss, humm, etc, out of the signal path, you have to keep the output impedance as low as possible, and the output voltage high. 4 volts is sufficient, but it serves a hidden purpose. All 12 volt decks without a switching power supply derive their output voltage from converting 12 volt DC line in, to 2V, or less output AC signal. Without a switching power supply, you cannot gain any more output voltage. It's not possible. What's more, you will have clipping at the higher volume settings. Something you want to avoid in the setting of all other components in your system. However, unlike your other components, you cannot adjust the I/O gains to get rid of the clipping. A switching power supply, if done right, can give you 4,5, in the case of some Sony units, 8v of output. This is clean, undistorted, non-clipped signal. It is the same concept as what your amp's power supply does. Brings in 12v DC, and after switching it to pulsed DC, rectifying it, and running it through a transformer, the voltage is stepped up to somethin like 24-36 volts. So, the output voltage aside...the clean non-clipped signal output you get from a switching power supply is all the reason you need to look at higer output voltages. Also, if you have an output impedance that is too high, say 2000 ohms, you must look at the input impedance of the next downstream device (say...an EQ). It must then have an input impedance of 10 times that amount, to drive it. That would be 20,000 ohms. Some devices don't have that kind of input impedance. With an output impedance of your HU (60 ohms), you can drive anything with an input impedance of 600 ohms or more. A zero ohm impedance would, theoretically, drive ANY input impedance device. As another note, you cannot induce a voltage across a dead short, right? Well, zero impedance at the output of a head unit is essentially a dead short (as far as radiated noise is concerned). As output impedance drops, it becomes more difficult for radiated noise to enter the system. [/QUOTE]
Insert quotes…
Verification
Post reply
Forum
Car Audio Discussion
Head Units
HU Pre outs
Top
Menu
What's new
Forum list
