what speakers to buy. keep blowing them.

[DAKSTER]

Doesnt the external amp bypass the pre-amp through the RCA's?

Not an expert here, but I would assume the preamp was necessary to put a signal through the RCAs at all?

If you turn your HU up to full blast, regardless of whether you are using amps, or what speakers you are using, you will have distortion. Better to set the amps to suit 75% volume on the HU and never turn it up higher than that, in my uneducated opinion. Thats what I've always done anyway.

Of course, then you are going to need some kind of shield to stop the passenger from twisting the knob that extra (speaker killing) bit..

 

[yZoH]

 

[sweefu]

Not an expert here, but I would assume the preamp was necessary to put a signal through the RCAs at all?

If you turn your HU up to full blast, regardless of whether you are using amps, or what speakers you are using, you will have distortion. Better to set the amps to suit 75% volume on the HU and never turn it up higher than that, in my uneducated opinion. Thats what I've always done anyway.

Of course, then you are going to need some kind of shield to stop the passenger from twisting the knob that extra (speaker killing) bit..

You need to do some more reading mate.

 

[DAKSTER]

Maybe I do. Thats why I made no claim to being an expert. Share the knowledge, I'm interested

 

[sweefu]

I can turn my headunit to full volume, and there is no audible distortion. Sure, there is some distortion present, in amplifier specifications you can look for it as THD (Total Harmonic Distortion)

You can set the gains correctly and have no audible distortion and have the level absolutely so low it will not effect your speakers.

For example,
I have an Alpine 9855r headunit, 4volt RCA pre outs
into
An Alpine MRV-F545 4x125wrms amplifier. Front channels to my tweeters, rear channels to my midwoofer, there is no gain across all channels.

 

[Nic92]

CLEAN, DISTORTION FREE SOUND! Set Amp Gains like a PRO! Its Easy! SMD DD-1 - YouTube

 

[vrollin]

WHAT?!?

I just...#### it....

No headunit is going to give you crystal clear headroom, ie no clipping of signal, through its entire volume range, especially at max... No amp for that matter... Its just not going to happen...

 

[DAKSTER]

So my assumption from that is that your Alpine unit doesnt allow you to turn it up beyond a certain level, that which starts creating too much distortion.

Most factory units dont have that feature (neither of my Kias for a start, and one of them has less than 1000km on the clock so it should be a modern enough HU lol), and the volume knob/switches will push max power and distort horribly if you crank them up. I assume a lot of aftermarket HU's also behave the same.

You've used your system as a benchpoint, and possibly your head unit is helping out here. On the Pioneer system in the Berlina, the distortion comes in at around 40 on a scale of 50. give or take a few depending on whats being played. This applies from the HU outputs, or from amps via RCA, makes no difference.

Am I correct in thinking the HU preamp is what supplies the signal to the RCA outs in the first place?

 

[HoldensBestVehicle]

best bet would be to get a good set of alpines, don't absolutely flog them, and you should have no problems

 

[vrollin]

back on topic, focals will soak up the power and love you for it