I'm trying to decide between Pioneer Premier DEH650 and 740mp..

i know the 740 plays MP3s but I don't use them..

aside from that the differences are miniscule..

but I am curious about the "preamp voltage"


650 is 2v
740 is 4v..

what does it mean and will the difference be noticeable in terms of sound quality?


thank you

 

The 740 with the 4 volt pre-out has the theoretical advantage of improved signal to noise ratio at the point where the signal reaches the amp. There may be something else to it as well, check the Faq's. I don't have all the specifics memorized.

 

It depends on whether or not you plan on setting up your system on amps. If not you don't have to worry about it, but if you are or planning on using amps in the future it might be of importance to you. Basically the higher the voltage on preamps the stronger the signal sent to your amps. With this relation the gains on the amps do not need to be turned up as high and you have less distortion.

 

The higher preout voltage will let you over-drive your amps, if you care about that (could potentially toast it though )... besides that it'll probably give you a higher signal/noise ratio for the preout signal delivery (as jmax said). I wouldn't stress the difference between 2V and 4V, it's probably not that big of a deal. Definitely wouldn't be a "high priority" factor in the purchase for me.

 

eclipse headunits are 8v....diamond audio amps support up to 12v.

keep in mind if you have an amp that doesn't support a good voltage, and you get a good headunit,t hen think of it as a sine wave. everything above will be considered spikes to the amp. that may/will cause damage

 

Ohhh, didn't know that. I was just told that the next time I pick up a headunit to get one that had more preamp voltage. But at that time I think my head unit was giving out less than 1 and a half volts.

That was my first deck when I was 16, a little cheapie under $200.

 

My first headunit was the high end of the day. It had 0.5 volt pre-outs. Even if you have a 24 volt pre-out headunit and an amp that has max input voltage of 2 volts you can still get it balanced out. You just wouldn't have as small of increments in the volume setting. Anymore I look for 4 volts minimum pre-out voltage. But I don't look at cheap parts when I put a system together. And I wouldn't use a Kia head gasket in my Maxima either.

I seriously doubt that 99.9% of people would be able to detect a sound quality difference between a 2 volt pre-out headunit and an 8 volt pre-out headunit. Not if the rest of the system components were properly set up.

 

thanks everyone

yes, i'm using amps, i'd like to think of everything i have as decent quality stuff.. zapco and crossfire amps, IDQ sub, Focal speakers.. i just don't have the desire to spend any more money on the stereo and need a good headunit to replace my DEH9200 which is acting up lately and the faceplate controls are destroyed.
If it's not a big deal.. then I guess I don't really need a 740mp..

thanks