good HU w/1 preamp vs. bad HU w/3 preamps?

[sumone 10+ year member]

head unit 1: I like it; 1 set of preamps

head unit 2: I don't like it: 2 sets of preamps & a sub preamp

(I wouldn't say I don't like it - I just think head unit 1 is better)

dilemma:

head unit 2 distorts earlier than head unit 1. (no amp hooked up; everything off head unit). however will it be the same for the preamps? since head unit 2 has basically 2 and a half preamps it would be easier when hooking up my amp. otherwise if I chose head unit 2, I'd have to split the 1 set of preamps into 2 and a half to get the same number of preamps as head unit 1.

question:

if the head unit distorts at point A when speakers are directly connected to it, does that mean that the head unit will also distort at point A when speakers are run off an amp hooked up to it? even though I like head unit 1 better, it only has one preamp as opposed to head unit 2's 2 and a half. but if this problem is alleviated once an amp is hooked up to it, I'd stick with head unit 2 - the one I don't like as much but is more convenient.

who hoo! I installed my first head unit! however I may be hurting something cause I kind of had to force all those wires and stuff in there to make the head unit fit...

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[allyourblood 10+ year member]

if the head unit distorts at point A when speakers are directly connected to it, does that mean that the head unit will also distort at point A when speakers are run off an amp hooked up to it? even though I like head unit 1 better, it only has one preamp as opposed to head unit 2's 2 and a half. but if this problem is alleviated once an amp is hooked up to it, I'd stick with head unit 2 - the one I don't like as much but is more convenient.

i think you'd be better off with HU 2. the distortion you're hearing is simply the amplifier in the HU beginning to clip. of course this will vary between HUs: some will be able to produce a cleaner signal at higher volumes. but - once you hook up an amp, you're no longer using the HUs internal amplifier. therefore, the point at which your speakers begin to distort will depend on your external amp, and not your HU.

so, in short, just use HU 2. your distortion problems should go away once you connect it to your amp.

abe m.

 

[helotaxi 5,000+ posts]

allyourblood is mostly right. It will not distort at the same level, but you will still get it to distort. Remember that a preamp is still an amp. It generally uses opamps rather than larger transistors and MOSFETs but it has the same limitations. Most all HUs are set up to where the preamp outputs will clip at about 2/3 volume. This becomes sooner if the bass or treble boost is used. Past the clipping point of the volume, you are just turning up the distortion.

The only problem with using the HU with the single preamp out is you will not have fader capability at the HU. You will need crossovers from another source as well. Most newer amps have those built in nowadays. If you want sub volume control you will either need a remote gain on the amp or get an external crossover with a remote on the sub output. There are many ways to work with a single out, if there weren't you wouldn't have been able to build a system back in the day cause most units only had one output.

 

[sumone 10+ year member]

ok, working with one set of preamps is ok cause I just split those 2 channels into 4 and they go in my 4 channel amp. 1&2 are for components and 3&4 are for bridged sub; the amp does have internal crossovers; just having 2 sets of preamps and a sub preamp is just convenient if I ever decide to upgrade in the future.

but I don't think you guys get it...this second head unit distorts like crazy! first of all the bass response is poor as hell. and it distorts way before it reaches max volume (flat eq). I mean it'll be nowhere near loud and distort like crazy; and believe me I know what loud is...being a non-spl guy;

The distortion is so bad that I put my STOCK radio back in and sacrificed having my aux-in for my mp3 player! I didn't put the previous aftermakret one back in cause then I'd have to reconnect all the wires and stuff...thank God I used screw-on connectors for the speaker wires and crimp-type for the control wires. my STOCK radio - at least it distorts when the volume's loud....

 

[helotaxi 5,000+ posts]

The internal amp in most HUs, even aftermarket ones, is horrible. They start to clip very quickly and the distortion gets out of hand almost immediately. The preamp outputs are a different story. They will probably clip before reaching max volume (true with almost all HUs) but they will not clip as nearly as soon as the internal amp will and with the external amp on the speakers, it should be plenty loud before you get to the limit of the preamp's capability.

 

[sumone 10+ year member]

^ cool...that's really all I needed to know even though it's already been said;

 

[sumone 10+ year member]

also, is there something I could've done wrong in wiring that wouldn't let me get optimal performance from this second crazy-distorting head unit?