Question about Infinity 475A Car Audio Amplifier

3 Answers

Another conundrum I want to connect my Amp to my existing BMW head unit - I have been told by some that I can take the feed straight from the Factory Head Unit - (which has no RCA pre-outs) using a speaker wire to RCA connector and others tell me I must have a Line Output Converter. I do not want to damage anything during the install, but before I spend lots of extra money on 4 channel LOC, can anyone tell me the definitive answer. The Infinity website says this"The RCA low-level inputs on the 475a have allow for connection to both a preamp level signal and direct connection to a high-level factory head unit. "but as the english is so bad in this sentence, Im just not sure whether to trust them. Allt he specs of the Amp are on the infinity website - but nothing seems to confrim this for sure!!Help me please.!!

Posted by on

  • 4 more comments 
  • alexbartman Nov 22, 2007

    no - the question really is does this AMP (infinity 475a) accept the high level output from my head unit
    Im pretty familiar with the general concepts - my big nightmare is that this specific amp is not specified,...

  • alexbartman Nov 22, 2007

    my head unit has 8 speaker outputs...
    Front Right +
    Front Right -
    Front Left +
    Front Left -
    Raer Right +
    Rear Right -
    Rear Left +
    Rear Left -

    my question - which I paid to have expertly answered is really to do with this amp specifically - does it accept the high lebvel outputs from my head unit - I think Im ok with the general wirign but the question is more specific and relates to my Infinity 475a amp....
    thnaks
    Alex

  • alexbartman Nov 22, 2007

    Hi there
    thanks very much for this - making more sense -
    so I ll go for a converter - as Im in the UK i was planning to go for these ones
    can you tell me if the following product will do the job
    http://www.edaudio.com/store/product_inf...

    the description is a "SoundGate LOC4.4 - 4 Channel LOC"

    thanks
    Alex

  • alexbartman Nov 22, 2007

    and finally.....what would happen if I connect up the head unit to the amp without a LOC?? WOuld it work at first and then fail or would it not work at all

  • alexbartman Nov 22, 2007

    I have 2 Autoleads PC1-601 (see www.ebay.co.uk item number 330176553387) - i just cant work out if this changes the signal or just turns the wires from speaker to RCA - there is a common gound wire on both - but I do not know much about electronics - all I know is that these Autoleads leads have no big box - they do seem quite flimsy - but finding LOCs in the UK is proving very very difficul...

  • alexbartman Nov 22, 2007

    do you think my autoleads connector will do the job?

×

Ad

3 Answers

  • Level 2:

    An expert who has achieved level 2 by getting 100 points

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

    Vice President:

    An expert whose answer got voted for 100 times.

  • Expert
  • 363 Answers

To check for yourself, get an Ohmmeter and see if the outers of the amplifiers RCAs are connected to the ground or each other. If so then it cannot take speaker signals directly.
I suspect the 'High Level' the manual speaks of are the 4volt auxilliary audio signals that can be found on some newer head units, not speaker signals.
Speaker level signals from a bridge amp CAN be used on grounded RCA inputs if the signal is first passed through a simple decoupler and attenuator.
Diagram to explain....
Another conundrum - c26567f.jpg

Posted on Nov 22, 2007

  • Martin B
    Martin B Nov 22, 2007

    In reply to "what would happen if I connect up the head unit to the amp without a LOC"



    At best a blown fuse or tripped HU protection.
    At worst, burning smells, irreparable damage and other bad stuff.

    Both terminals of the speaker outputs on your HU are held at 6Volts mean with respect to ground regardless of volume so even if you left the negative HU speaker wires off the amp input grounds, you will get a massive pop due to the 6V step every time the HU is turned on of off.

    You might even damage the speakers or amplifier.



    Benimur was drawing diagrams and replying at the same time as me so we had no idea of each other's responses. You can see we are both advising you not to experiment here.



    You really do need a converter to make the levels right!!!

  • Martin B
    Martin B Nov 22, 2007

    In reply to "do you think my autoleads connector will do the job?"



    I think so, Under the heatshrink sleeve in the middle of the lead should be components similar to those described in my first reply.

    Obviously you need to buy two if you want 4 channels that are fadeble from the front to back speakers via the HU.



    Regards

×

Ad
  • Level 2:

    An expert who has achieved level 2 by getting 100 points

    MVP:

    An expert that got 5 achievements.

    Sergeant:

    An expert that has over 500 points.

    Champion:

    An expert who has answered 200 questions.

  • Expert
  • 306 Answers

So you want to know if connecting the rca from deck to amp is ok, or that the deck doesnt have rca's and you want to connect using wires from deck to amp?

If the deck has rca out's use them, sound quality will be better. If deck doesnt have rca and the amp has "inputs" for wired (low levels are for sub's high levels are for mid's and tweeters.) connection should be fine.

Posted on Nov 22, 2007

Ad
  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

    Brigadier General:

    An expert that has over 10,000 points.

  • Master
  • 6,966 Answers

Hi,

The simplest/safest would be to buy the converter. Here are some examples that will accept 4 speaker inputs and give 4 RCA (line level) outputs.

But please be informed that most head units employ bridge type outputs where none of the speaker wires is grounded. This must be taken into consideration when choosing the converter since the output of the converter would be 4 RCA with a common ground whereas its input would be 8 wires (from the head unit) with none of the 8 tied to the ground.

Hope that this be of some help/idea. Pls post back how things turned out or should you need additional information.

Good luck and kind regards.

Posted on Nov 22, 2007

  • 1 more comment 
  • Louie  Role
    Louie Role Nov 22, 2007

    Hi again,

    High level would be referring to the speaker outputs of the head unit. As initially posted most if not all current head units employ bridge type output. None of the output's 8 wires is tied to the ground. Your amp has 4 RCA inputs. All 4 have a common ground. So basically you have input of 4 wires + 1 ground; your source is 8 wires with none tied to the ground. Hence my suggestion to go for the converter.

    The Infinity 475A could accept as much as 6V input signal (high level) but that is with respect to the ground. Some not so recent head units employ this type of output amplifier. One wire of the speaker is grounded.
    Pls refer to the simplified diagrams below of some head unit amplifiers.
    This type of amp uses an output where one terminal of the speaker is grounded.
    This would be the high level input suitable to the Infinity 475A.

    This type of amp uses a bridge type output where none of the speaker's terminal is tied to the ground.
    Since none of the speaker wires is grounded, it is not suitable to a direct connection to the input of the Infinity 475A.

    A typical external amplifier such as the Infinity 475A would use something like below for its input.
    where the input is with respect to the signal ground.



  • Louie  Role
    Louie Role Nov 22, 2007

    The product on the link you posted would seem to be able to do the job, however, pls verify from edaudio:
    1. if the SoundGate LOC4.4 will present itself as individual 4-8 ohms loads to the built-in amplifier of your head unit;
    2. do you need to retain the connection of the head unit to its current 4 speakers, if yes then that would mean 4 additional speakers for use of the Infinity, if not back to #1. The reason is from a technical point of view, a load (such as a speaker or 4-8 ohms resistor) must always be connected to an amplifier (whether external or built-in).

    Other than the above concerns, it should work out as advertised.

  • Louie  Role
    Louie Role Nov 22, 2007

    It would work all right - work defined as in definite increase in sound level.
    how long - depends on your settings. If you play for listening level, then I suppose it would work for a some time; if you prefer bass thumping where you can feel and not only hear, then I expect that it will not last very long. Either your head unit's built-in amps will burnout or you will overdrive your Infinity.
    Quality of sound - I sincerely have my doubts it will be at par with your expectations.
    At the end of the day, I think the question would really be "are you willing to take the risk?"

    Our responses/suggestions are to a certain extent based on frequent dealings of similar concerns. From a tech's point of view, it would be technically correct to use a converter or a simple decoupler and attenuator as SparkGap posted .

×

1 Suggested Answer

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
A 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
The service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
Good luck!

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

How do I hook up a sub woofer & speakers to my car stereo?


If you are replacing the existing door/deck speakers with replacements of the same size and not adding an amplifier, you will be able to use the existing wiring, making note of the positive and negative notation.
Subwoofers, on the other hand, require an amp. There are subs that have an integrated amp in the enclosure, otherwise you will need to buy a separate amp. Connecting the amp to your existing system will highly depend on what outputs your head unit (aka stereo) has. If it has pre-amp outputs, those can be run straight to sub amp. If there are not pre-amp outputs, you may have to buy a "high level" adapter that connects to the same head unit outputs as your speakers.

Jul 02, 2016 | Car Audio & Video

1 Answer

Clarion NZ502E audio problems


The issue has to be with either the head unit or the external amp that is being fed. Reverse the feed to the amp from the Clarion. If the audio issue now shifts to the other side the problem is with the Clarion. If the issue stays the same then the problem is with the amplifier.

Jun 19, 2016 | Clarion Car Audio & Video

1 Answer

My factory car amp does not allow the front door speakers to play highs can I connect those two speakers directly to the head unit connection and have the rest of the door speakers run through the amp ?


That will not work. The reason is frequency response. There are high and low pass filters installed on speaker systems. The reason is that no one speaker can handle all sound ranges. The other thing is that high range speakers are not high wattage speakers because they don't have to be. If you hook the high range to the straight feed from the amp, you will blow them out really fast.

Jan 23, 2015 | Car Audio & Video

1 Answer

My radio volume just stopped working but you can see the channels and change from different stations what is wrong with it


If you have volume but cannot control it, this is a common problem. The volume is optical so it may just have dust in it, but I have had zero luck cleaning them. The only solution I know is to replace the whole head unit.
If you have an HK factory stereo with no volume at all, and the four channels went out one at a time, the amp in the trunk has failed. Another common problem. The amp is on the driver side above the wheel well. You have to remove the driver side rear deck speaker to get the trunk lining off without tearing it. The screws that hold in the speaker are beneath the speaker grill in the rear deck. Good luck getting a 15-year-old speaker grill up without breaking the snaps. Slide a putty knive in from the sides to try to release them, but they will break anyway.
If the amp has failed, you can just bypass the amp but you will have no subs or tweeters. I did that while looking for a good deal on a junkyard amp. You can buy a new HK amp from BMW but they are prohibitively expensive. You could buy an alternate brand amp and add crossover circuits to power the subs and tweeters if you are really handy with electronics.

If you have an HK system in your BMW and you replace the head unit, use the antenna power wire from the new stereo as the 'on' signal for your HK amp in the trunk. Your FM may not work quite as well because the BMW head unit communicates with the antenna amplifier. Also, if you have a BMW CD changer in your trunk, no other head unit will communicate with that other than the original BMW head unit.
Other than the CD changer and the antenna amplifier, the wiring adapter that you can get from Crutchfield or from Amazon will make the stereo head unit replacement plug-and-play.
You may need a special five-sided wrench to get the old stereo out. You can buy that wrench on line if you can't force some other tool into those two cap screws that hold the stereo in.

Sep 18, 2011 | 1996 BMW 3 Series

1 Answer

What kind of wire do I need to install Infinity reference series 605cs with a JL Audio 10" sub and a Alpine Flex 2 amp? Can I use my factory head unit?


You can use the factory speaker wiring for the Infinity speakers you should purchase a amp kit which will give you everything to install the amp. See site below

http://www.sonicelectronix.com/item_18428_Raptor+ISPKBL4-BG+by+Metra.html
Well that all depends on the current audio system you have now is it just a basic or a premium factory system with a factory amp. Honestly you would get a better and cleaner sound if you change the factory head unit to a after market one which has preamp feeds and the higher the preout volt the better. Just make sure it is compatible with the amp volts input (Example 4v to 250mv) If you use the factory headunit you would have to by a high to preout adapter it connects to the exsiting radios speaker leads, but like I said before change the head unit you won't be sorry. Do not forget if you change the radio you need a radio install kit and the wiring harrness which converts the two radio plugs so you don't cut them so down the road you can remove the after market radio and just replug the factory right back in.

Apr 16, 2010 | Infinity Reference REF 605CS Car Component...

1 Answer

Factory amp turn on wire for 93 bmw 740i


u would need the factory service manual . find suspected turn n wire and a test light to it while turning on head unit will light up when the right wire is found . ideally a multimeter is better to check this wire for 12 volt or 500 ma of power , just be carefull

Dec 29, 2009 | Car Audio & Video

1 Answer

I need to install a max385vd in a 2002 pord f-350, do i need an install kit?


Regardless of whether this is an amp or a head unit, an install kit is either very helpful or necessary. If it's an amp, you'll need it for sure - you can't power an amp with 18 gauge factory power wiring like a head unit can use. You need to get at least 10 gauge power and ground wire, 18 gauge remote turn-on wire, and RCA patch cables to conduct the sound. If you have a factory head unit, you'll also need a line-level adapter to give you a source for the RCA patch cables.

If this is a head unit, you'll need the adapter harness to plug your existing stereo harnesses into the new head unit. It makes it simple - the wires on the new head unit are color-coded for what they do, and the adapter harness is identically coded. Match the colors, then plug it in. You may also need an antenna wire adapter (some cars require this).

Aug 10, 2008 | Clarion Car Audio & Video

1 Answer

How do i install a subwoofer and amplifier to an exhisting car audio system


Hi,

The basic would be to wire the sub amp to your batteries with the trigger/remote wire powered by your car stereo/head unit. When your head unit is turned on it will in turn power up the sub amp. Of course the sub woofer need to be wired to the amp. For the signal/audio wiring, normally, the head unit has a stereo RCA female connectors at the rear intended to be connected to external amps through a pair of shielded/audio cable terminated both ends with RCA males. Some units have a special RCA specifically for subs. Most eternal amps also uses RCA for their inputs.

If the existing car audio system has already an external amp and your plan is to add on to this, the audio/signal from the head unit could be split to provide both for the existing and the new sub amp.

If the existing car audio does not have an external amp and their are no RCA connectors at the rear of the head unit, it is still possible to connect an external/add on amp by using an adapter that connects to the speaker wires of the head unit and converting it out to line level (through RCAs) appropriate for the input of the amp.

Hope this be of help/idea. Pls post back how things turned up or should you need additional information. it would also be nice if you can post brand/model of your head unit and intended sub amp.

Good luck and kind regards.

Jan 23, 2008 | Audio Players & Recorders

Not finding what you are looking for?
Infinity 475A Car Audio Amplifier Logo

231 people viewed this question

Ask a Question

Usually answered in minutes!

Top Infinity Car Audio & Video Experts

xxxxxx xxx

Level 3 Expert

4932 Answers

Tygh Duval
Tygh Duval

Level 2 Expert

300 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22326 Answers

Are you an Infinity Car Audio and Video Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...