2014 GT Lost Base on factory head unit with Polk speakers

[Gio26NJ]

Thanks V8 and RedBaron for the great pieces of information and input for people like me who are not so knowledgeable in this field.

What speakers would you recommend over the factory ones using the headunit without the need for an amplifier? or would it not even make a difference? I have the Bose in our CX-5 and happy with it but for my 6 which is the Touring I would like to add to the sound that is very much lacking, huge difference between the factory Bose and factory Touring speakers.

 

[RedBaron]

What speakers would you recommend over the factory ones using the headunit without the need for an amplifier? or would it not even make a difference? I have the Bose in our CX-5 and happy with it but for my 6 which is the Touring I would like to add to the sound that is very much lacking, huge difference between the factory Bose and factory Touring speakers.

I have the Polk 651's in my non-Bose, and frankly it hasn't made much of a difference and the sound is still poor (to the point that even my wife, who is certainly no audiophile, complains).

So I'm in process of swapping out the head unit, both to improve the sound quality and get rid of the stupid USB (lack of) functionality. Still in design/order stage right now though. Hoping to reuse the factory center console USB/Aux sockets and rear camera, but will post more later.

 

[vasichkin]

I have the Polk 651's in my non-Bose, and frankly it hasn't made much of a difference and the sound is still poor (to the point that even my wife, who is certainly no audiophile, complains).

I dont understand. She complains the the sound got worse after installing new polks or it vot better but its still bad.

 

[V8toilet]

I have the Polk 651's in my non-Bose, and frankly it hasn't made much of a difference and the sound is still poor (to the point that even my wife, who is certainly no audiophile, complains).

So I'm in process of swapping out the head unit, both to improve the sound quality and get rid of the stupid USB (lack of) functionality. Still in design/order stage right now though. Hoping to reuse the factory center console USB/Aux sockets and rear camera, but will post more later.

Please let us know how that works out. Mine sounds great with the exception that the tweeters have a weird overtone to them. I think I narrowed it down to either a ground loop or it's the factory radio.

On a side note; my Polks sounded lifeless and flat on factory power until I put an amplifier on them, which made them sound way better.

 

[RedBaron]

I dont understand. She complains the the sound got worse after installing new polks or it vot better but its still bad.

It may be a bit better, but still bad. I since replaced the head unit with a Kenwood. She likes it now

 

[2:35toOne]

To chime in on what is a very frequent topic: the use of a line-output converter (the AudioControl LC6 is mentioned frequently): these are NOT needed IF the aftermarket amplifier has "balanced differential" RCA inputs. The Mazda head unit's speaker wires can be connected directly into the amplifier's RCA inputs...typically by using optional RCA cables with speaker wire pigtails. I've worked with the LC6 and find it to be a top-notch adapter. But it's only needed if the amplifier doesn't have either speaker-level or balanced differential inputs. Personally, I'm always in favor of fewer components in the signal chain--and using an amp with this circuitry means the amount of time and space for the installation is simpler.

I know many amplifier companies offer models with the balanced differential input feature, from Kicker, JL Audio, JBL...etc. Amp makers prominently call it out in their specs, so it's difficult to overlook.

Perhaps this will simplify someone's work when adding an amplifier to the stock Mazda deck.

 

[V8toilet]

They commonly refer to that as speaker level inputs I believe unless you're talking about something different. The quality of the sound with an Audio Control line driver/converter in your system is better because you get a nice clean boosted input signal for you amplifier vs the lower quality circuit that comes with the amp (especially cheaper amps). Audio Controls LC6 also has circuitry that restores the bass lost through some factory radios and you're able to control the volume (not boost) of the bass if you have a separate subwoofer with a separate control knob. I like this feature because I can Taylor the amount of bass to suit the song or driving conditions. Still you are correct in that speaker level inputs are all you need for most systems.

 

[2:35toOne]

Your response let me know I should have been a bit clearer on the "balanced differential" inputs. What I'm attempting to clarify is that if the aftermarket amplifier has this type of input, the amp doesn't need dedicated "speaker-level" inputs; it can receive either line-level or speaker-level signals from the upstream component, whether it's an OEM radio or amplifier. This is a relatively new feature in amplifiers. They used to only come with standard unbalanced inputs, where they accepted a smaller range of input voltages and the RCA shields (carrying the audio ground) were tied together. If the installer connected the speaker wire outputs to this type of amplifier, the upstream component would activate its protection circuit, as it thought the speaker cables had been shorted to ground. This amplifier design was common also because OEM integration was very rare, so designing in features that supported this wasn't a good financial choice. Today, things are very different.

V8, you're absolutely correct the LC6 is a fine piece, with many useful features. I think AudioControl is one of the best, smartest companies out there, with a great catalog of car and home products. Everything they make is constructed using design principles that originated in the pro-audio world, a philosophy brought in by the company founder Greg Mackie. But, if we restrict our discussion down to simply the question of whether a converter is absolutely needed when connecting an OEM radio/CD unit into an aftermarket amplifier, then answer is no, it's not. One simply needs to select an amp with either dedicated speaker-level inputs or balanced-differential RCA line-level inputs.

All radios with built-in amplifiers can produce around 9 volts RMS on the speaker leads. This is plenty of signal to feed into an aftermarket amplifier. The LC6 can produce around the same amount on its outputs--of course, it does this using its internal high-voltage power supply. This is a very healthy amount of signal, which ensures no noise will be picked up on the RCA cables feeding into the amplifier. Interestingly, the head unit in my CX5, a 2013 GT with the Bose package, produces almost 4.0 volts RMS on the pre-amp outputs. This places it well above entry-level aftermarket decks that typically don't have internal DC/DC converters, limiting their preamplifier signal levels to 2.0 volts.

Again., the LC6 is a fantastic piece that adds some very useful features. It's just that it's not absolutely necessary today for adding an amp to an OEM radio.

 

[2:35toOne]

The "can you" question is a complex one. Yes, one CAN install the Alpine amplifier as a replacement for the Bose amplifier, but it will likely result in a poor outcome. I say that because the Bose amplifier is more than an amp: it has electronic crossovers that shape which frequencies that are sent to each speaker...it has speaker-specific equalization, and it has limiting circuits that ensure bass is rolled back as the volume increases, ensuring the speakers sound full at low volumes, but aren't damaged by receiving too much low-frequency energy at high listening volumes. The Centerpoint Bose amplifier also performs the "surround sound" decoding, deriving the center and rear signals from the CD player's Left and Right signals. The Bose speakers and amplifier should be viewed as a "system" because they work together. Neither works well without the other. Bose's claim to fame is actually extracting a surprising level of performance from what are in general low-cost speakers.