question for stereo guru, regarding head unit
 

Hi guys,

I wonder how much sound quality I lose by switching from an Alpine head unit (CDM 7829) to this Boss head unit. The reason I want this head unit is the SD card to store MP3 while not spending much $.

Currently I have an Alpine (7829) head unit and an Alpine CD changer. The Alpine head unit has 4 channel RCA connected to a 4 channel amp for 4 speakers. From this amp, it bridge to another amp for the subwoofer, which power two 15" at the rear seats.

I believe I have to convert the speakers output from this Boss unit to RCA then plug directly into the amp.

My guess is that sound quality doesn't change much, because sound quality base more on speakers quality, when I have all the amps handle the power output. Am I correct?

Here is the Boss unit:
http://www.amazon.com/dp/B004S50WPG/?tag=mh0b-20&hvadid=7000638433&ref=pd_sl_2z7b5q414t_e

The unit does have one set of RCA outputs, which should give you good sound, i would assume those are for the front channels and if you use rear speakers, those would be fed from the built in amp?

Do you have a crossover, or does the amp have a built in crossover to feed the subs the low frequencies?

I don't see any separate crossover anywhere. I do see the 4 channel amp bridge out to the second amp for sub . The Alpine have 4 RCA jacks, they all go to the 4 channel amp.

Doesn't any amp has adjustable crossover to adjust the frequency? The sub's amp is hard for me to get to to check on it.

rnin,

Some amps will have an adjustable crossover, but it's not the norm. Judging that your subs are using a separate amp, I think that there is a good chance it has a crossover built in or they are getting fed a full signal and it isn't causing problems.

The new deck only has one set of RCA outputs, so you'll either need to "Y" off of them to feed all your channels or use the outputs for the front speakers and the built in amp for the rear speakers and the RCAs for the front and subs. If you go the "Y" route, the fader on the head unit won't work, but you could turn the gains down on the rear channels of the amp to adjust. Personally, I don't care for rear speakers and just use fronts and a sub in my Targa.

Plus, 50Wx4, probably REQUIRING 2 ohm speakers, means the BOSS lacks a DC-DC MOSFET voltage upconverter putting in the low grade audio class.

If you value audio this highly... BASS BLING, you should be driving a Lexus LS430 series, NOT a 911.....

If you are going to upgrade your stereo,you should put in a nice system with blue tooth an amp and a good set of speakers and maybe a subwoofer.
It will not take away from the 911 experience ,all you have to do if you want to hear the awsome sound of your 911 is turn the stereo off and then if you take a highway drive or feel like listening you can enjoy a good clean stereo sound.best of both world.

BOSS head unit @ $25 indicates Op isn't interested in high fidelity, just car shaking BASS...

UPGRADE..??

No, DOWNGRADE...!!!

rwest,
Here I found some pics of the 4 channel amp, Alpine MRC F250

input, it has options for RCA and low level speaker wires.
http://img3.auto24.ee/auto24/product...1/14723011.jpg

And here is the pic of the output to another amp, RCA on the right, with all kind of adjustments.
http://img1.auto24.ee/auto24/product...5/14723025.jpg

I think I am ok with the connecting options. The thing I need to know now is if sound quality will degrade much by swapping only the head unit.

For such a long time, I don't listen to music in the car much anymore, except when I feel sleepy on the long trip (this is why I don't even remember what I have in my car). Man, I don't even drive this car that much. When it comes, I need some loud and reasonable sound to keep me awake.
The reason which lead me to this thought is because I see this price, with the SD CARD.
- one, I can just pop the SD card in and it has all the MP3 in there
- I can get rid of the CD charger
But I don't want to ruin much the current sound quality I have. Will I?

Thanks.

Simple answer/solution...

Hook the BOSS' 2 RCA outputs to the amp's input, bridge the f/r together, play something that has a large DB range. Now connect the BOSS' front speaker outputs using RCA adapters, bridging the same way. You might have to attenuate the BOSS' high (speaker drive) output level so as to not overdrive the alpine inputs.

Listen closely to the 2 configurations.

Unless you have a tin ear the loss in dynamic range, flat-topping of the high notes, using the speaker outputs will be VERY noticeable.

"keeping awake...."

Not advisable, but...

Coke for sugar content, and.... CHOCOLATE.

Make sure you get a decent warranty with your new stereo. I've had experience with Boss and although the equipment functioned as designed, I did have to return a couple of their amps due to premature failures. I've installed car audio for 25 years and suggest holding off until you're able to get a better quality unit.

do you have an iPhone/android phone as a music/mp3 source? If so, it's now surprisingly easy to add bluetooth functionality to an existing stereo (even your existing alpine), especially if you're willing to sacrifice the cd changer. You'd basically get an adaptor that plugs into your alpine that allows it to accept a line level signal and then buy a bluetooth audio adaptor that interfaces with your phone and sends the audio out via line level rca jacks . . .

Sorry, my apologies....

Just looked up your Alpine amp and so you must be well used to hearing signal flat-topping at high signal levels.

What you are saying is that regardless of brand and all, talking about the different between low level RCA and speaker wires level alone, there is noticeable different?

Will the result the same if the amp has both option of input, RCA and speaker wire? Will the result is still the same ?

Thanks.

The Boss unit is on sales now and is cheap enough that I am not too worry about return, knowing their warranty policy is not so good. What I consider is the labor, don't want to swap it in, then have to swap it out again for nothing.

Strange is that long time ago, if I remember right, Boss is the higher end product (home audio). What makes them so cheap now.

Well, years ago when I was younger and loved to play with car audio, I did changed head unit which experience low level RCA output and speaker wires output to amp. but I can't remember how diff in sound quality. Again, I have not touch these stuff for such a long time.

Oh Ron, Just get better, put the top down and drive her, It's a nice high 70's out right now. :D

rnin,

Generally, your low level or RCA outputs have a lot lower level of distortion, so when you take the speaker level outputs that have gone through the built in amp with a high level of distortion, about 10%, you end up amplifying that distortion to boot, so use the RCA outputs to your amps for the best sound.

I think you could pretty easily run power to the Boss unit and plug the RCAs into your amp and speaker set up to see how it sounds. The Alpine unit will be of higher quality, but given the noise floor and the music quality of a SD card, I doubt you'll easily notice a difference.

I can't tell from the picture, but it sure appears like the one amp has a crossover built in.

Best,
Rutager