Also, any of you electrical savy people plan on adding RCA's to other peoples HU's for a fee???
If I had time to do the mods I would. Right now work has me in overdrive....
1) Why is polarized electrolytic type capacitor suggested over non polarized?
2) My amp (RF 200a4) has "sensitivity" between 250mV and 4V and a 20kohm input impedance. I calculate a -3dB at 20Hz capacitor value of 0.96uF. Is this correct? What do you think of the "sensitivity"? Is it sufficient without needing a line driver?
3) You mention choosing your cap based on reducing DC offset. How does the cap value affect DC offset? I thought any size cap will block DC.
4) Why the 50V rating? what kind of DC offset are we talking? i'd measure it, but i don't have a scope. I would prefer to use smaller rated caps due to size constraints.
1.) No real reason, just so people wouldn't have to ask which one to get. Personally I think it is easier to find a wider variety of polarized electrolytic capacitor values.
2.) Pretty sure your calculation is correct. 4v sensitivity probably means you will need a line driver.
3.) If you go too low of a farad value, it is my understanding that you will not sufficiently block all DC offset. I forget where this scenario is the case, but I'm pretty sure it exists. I think I meant to say choosing a cap based on impedence for that part.
4.) I chose 50v because I never took the time to trace back where the amp chip hooked up throughout the entire unit. The amp chip has a supply voltage of 25v, with a 65v peak surge. I forget what dc offset was when I initially checked it, but it was high,somewhere in the V range (not mv range). The volume chip has a max supply voltage of 10v. You could probably use a 16v or 25v and be fine.
As to using a smaller volt rating to put in a larger farad cap, testing showed little improvement in frequency response. I was originally using .96uf 25v caps, but when testing I saw less than a .5db frequency response difference at the low end between the .96uf/25v and the .47uf/50v. Because of this, and the fact that I didn't want to trace the entire amp section, I chose the 50v.
Has anybody else tried the mod to remove the loudness feature? I think it is the reason my right/left channels are at such different volumes. I put the CD player in my car tonight to see how bad it really was. To make it even I have to adjust the balance so that it is 1 away from all the way left.
Sounds like you didn't bridge one of the smd pads. You need to bridge the smd pads so you can have a half-voltage reference going to the loudness pins. There is a resistor for each loudness pin that connects to the half-volt reference. Without this voltage, the volume ramps up to full volume at what should be only half volume.
As an observation, removing the loudness countour really brought back sound quality at lower listening levels(less than half volume). I always found the lower listening levels tinny sounding, now it is natural and even.