BestCarAudio.com

Showcasing the Best in the Mobile Enhancement Industry

Showcasing the Best in the Mobile Enhancement Industry
  • About
  • Upgrades
    • Marine Audio
    • Motorcycle Audio
  • Articles
    • Bluetooth
    • Car Audio
    • Motorcycle Audio
    • Navigation
    • Remote Starter
    • Satellite Radio
    • Smartphone Integration
    • Test Drive Product Reviews
    • Vehicle Insights
  • Profiles
    • Installation Profiles
    • Installer Profiles
    • Retailer Profiles
    • Vendor Profiles
  • Products
  • Dealer Locator
  • Shop
  • Facebook
  • Twitter
  • Instagram
  • 0 items

Does Preamp Voltage Matter?

May 4, 2017 By BestCarAudio.com 6 Comments

Preamp VoltageFor almost as long as there have been car audio enthusiasts, they have been adding amplifiers to their vehicles to increase the power available to drive their speakers. More power means we can turn the volume up higher without distortion. When it came to connecting amplifiers to speakers, the first power boosters connected to the speaker wires of the radio. Now, modern head units offer dedicated RCA preamp outputs to make things easier.

Manufacturers specify how much voltage their source units can produce on these preamp outputs. Most radios offer at least 2 volts of signal, but some offer 4 volt, 5 volt or even 8 volts. Does this preamp voltage matter? Does more voltage make your system louder? Read on to find out.

Signal Chain

Preamp VoltageWhen we install an aftermarket radio in your dash and connect it to the amplifier, we have to make at least one adjustment to ensure everything will work properly. We refer to this step as “setting the gains.” This procedure involves matching the output voltage limit of the source unit with power production capabilities of the amplifier to ensure that both achieve maximum output when the volume is cranked all the way up.

Adjusting an amplifier’s sensitivity is, in theory, a simple process. That said, there are many things to take into consideration. How loud is the source material recorded? Does the head unit distort at full volume? Has anyone adjusted the radio’s tone controls or equalizer? Does the amplifier have any tone controls? If any one of these criteria are overlooked, the sensitivity adjustment may not be accurate.

What is the drawback to an improperly configured sensitivity control? If it is set too low, then you cannot get all the power available from the amplifier to your speakers. If the sensitivity control is set too high, then you can easily distort the output of the amplifier. A second side effect of adjusting the sensitivity control too high is that you increase the noise produced by the amplifier. Nobody wants to hear a hiss in the background of their music, so setting things properly is critical.

What Does High Preamp Voltage Do?

Preamp VoltageSome intensive research among several of us “old” car audio enthusiasts revealed that there were even a few twin-shaft cassette receivers with high-voltage preamp outputs. Some sales and marketing folks decided that more voltage meant more volume. In the early ’90s, several head unit manufacturers started marketing their radios as having high voltage preamp outputs. If nothing else changed, sure – in theory, more voltage means more output. That said, if you swap from a 2 V source unit to a 4 V, and then readjust the sensitivity control on your amplifier down to compensate for the extra voltage, the maximum output level should stay the same.

If more voltage does not make your system louder, what is the benefit of this extra voltage? The answer is a reduction in gain of the amplifier and, thus, a reduction in potential noise. If your amplifier is set up to produce full power with a 2 volt signal and has a subsequent signal to noise ratio of 85 dB, then it is not unreasonable to expect that the noise would reduce by about 3 dB when we turn the sensitivity down by the same amount.

To the Test

We set up a premium consumer-grade amplifier on the lab test bench. It had an S/N Ratio specification of 89 dB when producing 1 watt of output and connected to a 4 ohm load. This is a pretty good rating these days. We set the amp up to produce 1 volt of output with a 1 kHz sine wave at a reference level for our function generator at -30 dB relative to full signal. We then took a long frequency response measurement.

The next step was to reduce the output signal of the function generator by an arbitrary amount – we chose 6 dB. We readjusted the sensitivity control of the amplifier so the output level was once again 1 volt and took another long frequency response measurement.

The results of the two measurements are shown in Figure 1.

Preamp Voltage
Figure 1, output dropped by 6db.

In Figure 1, you can see the large spike in frequency at 1 kHz on the right side of the screen. We zoomed in to fill the screen with as much information as possible below this frequency. The gold line shows the background noise produced by the amplifier with the sensitivity control at the lower of the two settings. The green line shows the background noise when we increased the sensitivity of the amplifier by 6 dB.

Figure 2 shows the difference in noise level at 100 Hz. Not surprisingly, the difference in noise is just under 6 dB.

Preamp Voltage
Figure 2, just under 6db of noise difference.

Conclusion

When it’s time to go shopping for a new source unit, among the dozens of cool connectivity features, options for display technologies and different brand names, paying attention to specifications is still important. If you are planning to add an amplifier to your mobile electronics system, make sure your source unit can produce at least 4 volts of output on the preamps. This extra voltage will allow your installer to reduce both the sensitivity controls on your amplifier and the background noise level of the system.

Visit your local mobile electronics specialist retailer today for more information on which source units have high-voltage preamp outputs.

Share this:

  • Tweet
  • Click to email a link to a friend (Opens in new window) Email

Related

AudioControl LC2i

Product Spotlight: AudioControl LC2i

Years ago, car audio specialist retailers were a destination for the latest in source unit technology. Bluetooth, MP3 and WMA playback via USB and GPS-based navigation brought clients in to upgrade their factory radios. In the past few years, these features and more have become standard in many factory infotainment…

RCA Y-Cable

Question of the Month: Do Radios with One Subwoofer Output Need a Y-Cable?

For September's BestCarAudio.com Question of the Month, we will look at car radios with a single subwoofer preamp output jack. There seems to be some confusion regarding the perception of quality associated with this design. Further, there are questions about whether or not your installer will need a Y-cable to…

RCA Y-Cables

RCA Y-Cables, Friend or Foe?

If you spend any time reading car audio discussions on Facebook or in forums, then you will have undoubtedly come across comments involving the supposed drawbacks of using RCA Y-cables. There seems to be a lot of misconception or misunderstanding about how preamp signals works, and this misinformation leads to…

Filed Under: Car Audio, ARTICLES, Resource Library Tagged With: Amplifiers, Gain, Radios

About BestCarAudio.com

BestCarAudio.com Magazine is the premier resource for accurate information about car audio and vehicle accessory upgrades. We are staffed by mobile enhancement industry veterans who are retail store owners, world-class installers, product developers, and trainers. Our Editor-in-Chief, Dave MacKinnon, is the industry's best-known writer and professional product reviewer. He uses his decades of experience to ensure that our published content is accurate, informative and entertaining. From car audio systems, lighting, remote starters, and window tint to how best to enhance your motorcycle, boat or powersports vehicle, we cover every aspect of the mobile enhancement industry in explicit detail to ensure that you choose the best upgrades possible.

Comments

  1. BestLaura says

    May 1, 2018 at 4:08 pm

    I see you don’t monetize your site, don’t waste
    your traffic, you can earn extra bucks every month because you’ve got hi quality content.
    If you want to know how to make extra money, search for: Ercannou’s essential adsense alternative

  2. VinnieB44 says

    July 12, 2019 at 10:03 am

    I have a PQ10 and PQ20 ADS Amplifier. Old School. Will a new head unit with 4Volt preamps damage my amplifiers?

  3. BestDonte says

    July 18, 2019 at 1:15 am

    I have noticed you don’t monetize bestcaraudio.com, don’t waste your traffic,
    you can earn extra cash every month with new monetization method.

    This is the best adsense alternative for any type of website
    (they approve all sites), for more details simply search in gooogle:
    murgrabia’s tools

  4. Oversea Wedding says

    December 9, 2020 at 1:56 am

    Hello, i believe that i noticed you visited my site so i came to ?return the choose?.I am trying to find issues to enhance my
    web site!I suppose its adequate to make use of some of your ideas!!

  5. Lilly says

    December 14, 2022 at 12:13 pm

    I was confused about my car audio system. But finally i get from this nice car audio blog what i want. And now i m going to upgrade my car audio system.

  6. Dave says

    January 26, 2023 at 10:13 pm

    I was wondering something. My factory radio puts out 8.3 volts and my amplifier put’s out 6 volts, but my cheap line output sees only 1.5 volts. My target amplifier gain voltage to set is 40 volts. However, due to my line output only producing 1.5 volts, does that mean I have to turn the gain (voltage) much higher to compensate for the weak input that can’t match the amplifier?

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

You are here: Home / Car Audio / Does Preamp Voltage Matter?
Kicker ad
Audison Forza

Save Time and Money!

Our buying guides will help you make educated decisions when upgrading your vehicle. Click the image above to shop our affordable and informative buying guides.

Industry Profiles

Broken Silence Mustang

Project: Broken Silence: The Grand Finale!

November 5, 2024 By Dave MacKinnon 

In early August 2024, the team of Sony Car Audio, GoFast Solutions, and Broken Silence Custom Car Audio in Greenwich, … [Read More...]

MECP AD 2025

Press Releases

JP-PPKT-1
Metra Begins Shipping All-In-One Vehicle-Specific Audio Kits
Firstech Re-Launches Drone XC Dash Cam Promotion
DroneMobile X2MAX-LTE
Firstech Ships DroneMobile X2MAX-LTE with Advanced Vehicle Data
Todd Ramsey
The Todd Ramsey Memorial Scholarship Foundation Launches to Honor Legacy
JP-1019 Soundbar Adapter SEMA 2024
In-Demand Late Model Jeep® Solutions Coming Soon from Metra Electronics

Vehicle Insights

2025 Hyundai Palisade

2025 Hyundai Palisade Calligraphy. Almost the Genesis.

2025 Toyota Tacoma

2025 Toyota Tacoma Trailhunter. Get Off the Beaten Path!

Find Facility Near You

Subscribe to BestCarAudio via Email

Enter your email address to subscribe to BestCarAudio.com and receive notifications of new posts by email.

Popular Categories

  • Car Audio
  • Window Tint
  • Remote Car Starters
  • Vehicle Insights
  • Radar Detectors

Supporting Manufacturers

  • Compustar
  • Hertz
  • Momento
  • Rockford Fosgate
  • Sony
  • Kicker

Contact

  • Editorial
  • General
  • Advertise
  • Dealer Locator Guidelines

Miscellaneous

  • Profile Request
  • Press Release Guidelines

Sign up for our newsletter today. Opt out at any time with 1 click.

  • This field is for validation purposes and should be left unchanged.

BestCarAudio.com is a product of 1sixty8 media, inc. · Copyright © 2025 1sixty8 media, inc. · Privacy Policy · Website by 1sixty8 media, inc. · Log in

 

Loading Comments...
 

    Notifications