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Crossover and gain rare question

 

New member
Username: Zneon

Durango, Durango Mxico

Post Number: 4
Registered: Jun-04
I'm not sure about somenthing. Since I like to take all of the juice i can from my amps and speakers (without distortion), i set the values to its maximum, but to a level where it does not clip. I have an Alpine 9811 Head Unit (4v RCA out), and a Hollywood RHV-1200D Class-D AMP. To set my gains, I turned the volume (0-35) to its highest position (35) next I turned up the gain until it clips, then i lower to a point where it does not clip. It sounds very good, but something i noticed was that when i turned the volume to a level higher than 28, the subwoofers did not sound louder. I'm not really sure but as my ears let me distinguish, i think it sounds louder at 28-29 than it does at a higher level. But this does not happen with my 6.5" speakers. What is this and what can I do?
Another question:
I read here that to set the gains, one should set the volume to from 75% to 90%. I have an Alpine Head Unit, even tough this is a high quality head unit, should I set the gains with the volume set within these values?
If I do, then, isn't it loosing some volume?

Is there any way to check the voltage of the amp gain?, because sometimes one can't tell the exact position of the gain knob.
Is there any way to adjust gains and volume, etc. using a voltmeter?, because osciloscopes are quite expensive.

(Using a Mid/High set)
When a 12dB/Oct passive crossover is installed, it produces a 180° phase shift. So you have to wire the speakers the opposite way(- > + and + > -).

Have the 12dB/Oct passive crossovers already inverse inputs? (I mean that if x-overs already know that the phase shift is 180° and when you wire the (+ power wire) to the x-over (+) you are actually hooking it up to the (-)?

Or the crossovers "aren't aware" of the phase shift and you do have to hook the inputs inversed?

If i want to inverse the wires to avoid the 180° shift, the only thing I need to do is inverting the wires that power the speakers, I'm I right? (Not the tweeter and mid wires after the x-over)

And, Is it better to leave the shift or inversing the wires?
 

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 4488
Registered: Dec-03
this should answer everything about how to set gains the right way:
http://www.bcae1.com/settinggainswithscope.htm

as vor the perceived volume, you may want to get the system metered to really test out that theory.
the amps cound be clipping, the speakers could be reaching Xmech, or it could just be your ears.
It's difficult to say remotely. I'd guess it's one of my first two guesses though.
once the speakers reach mechanical limits of excursion, power won't much matter. Once the amps reach full output, you hit a limit as well.
Also try things like sound deadening the car, or cracking the windows to see if it changes the perceived volume.. this could indicate a flaw in system design based on the car's cabin design.. there are fixes to that, but you need to isolate the problem first.
 

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 4489
Registered: Dec-03
oh, as for an EQ or XO and phase-shift, any electrical component used in those devices, such as a capacitor or resistor will induce a specific amount of phase shift, but you need to know the order of crossover used, how they're wired, etc in order to even begin to calculate that phase shift.
Then you need to take into account speaker positions relative to listener position as well, if you really want to adjust phase properly.
There are devices sold to set phase for each channel independantly and so forth if you like, or you can do it the old fashioned way, forget measuring shift, and do it by ear.
change phase around for each set of speakers, and see what sounds the best to your ears. Leave it as it sounds best, despite actual convention.
As for how to change phase, just swap pos and neg at the speakers or the amp. all it takes.
won't hurt anything as the sine wave a speaker receives is AC voltage anyway.
 

New member
Username: Zneon

Durango, Durango Mxico

Post Number: 5
Registered: Jun-04
Yeah, didn't know all that.
Thanks a lot, I really like to be sure with the answer of an expert.
 

Gold Member
Username: Glasswolf

NorthWest, Michigan USA

Post Number: 4531
Registered: Dec-03
hope it helped
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