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Basstronics wrote:A) Nobody is trying to "win you over". Quite frankly I dont think Kiki (or anyone) could give a rats ass if you agree or not with him.

that was a quote from kiki that i used in my post

if you want to me about it, do the same for him.

its pointless... there is no "discussing" in this forum unless the big wigs agree with you

Apparantly to disagree is to get into a pissing match.

Well you got me on one letter...

But fact still remains. This thread got hijacked on a BS topic not even pertaing to it where you purposely keep pushing the subject.

If you have such a problem with the way things are run here you dont have to visit. [/door]

Im not going to say crap to him. Hes the Mod, your the member. Your the one that keeps pushing the argument based off his posts. You have presented no information first, just arguments.

Your fully welcome to disagree. Your fully welcome to your opinion. Which your all about.

Your argumentive by nature. Your posts are all almost on argumental topics. You have provide some, but little real content...

Basstronics wrote:Well you got me on one letter...

But fact still remains. This thread got hijacked on a BS topic not even pertaing to it where you purposely keep pushing the subject.

If you have such a problem with the way things are run here you dont have to visit. [/door]

Im not going to say crap to him. Hes the Mod, your the member. Your the one that keeps pushing the argument based off his posts. You have presented no information first, just arguments.

Your fully welcome to disagree. Your fully welcome to your opinion. Which your all about.

Your argumentive by nature. Your posts are all almost on argumental topics. You have provide some, but little real content...

I "push the envelope", yet kiki posts in the same nature as i do.

There is a double standard and in situations like this, there need not be - him being a mod doesn't automatically make him right and me wrong.

I didnt' feel like posting on every letter... lol today I'm a bit more busy :)

Perhaps we can do some "alphabet soup" another day.

Show me one post where he picked the argument with you first...

Basstronics wrote:Show me one post where he picked the argument with you first...

there was no argument picked

He said a car was an inferior environment that didn't warrant the use of such "high end" cables.

I responded and said it was no worse than a house... and he disagreed... and so on.

I never "picked an argument"... if you want to say that, kiki "started" it by saying something I felt was incorrect... but thats such a stretch anyway.

discussion....

What's with all the "quotes"? lol

Hey, I measured the input resistance on a couple of amps I had laying around including a lil Nakamichi home reciever/amp/preamp. They were all between 4-14 kohms. What was interesting was the Xtant A2002's resistance varied with gain, but the PPI 2025am's resistance remained constant.

Are these last two examples of variable "sensitivity"(A2002 with a simple pot in the signal path) and variable "gain"(2025 with a preamp stage that uses a pot in the feedback loop of an opamp)?

The feedback pot would be Rf in this circuit:

http://webpages.ursinus.edu/lriley/ref/ ... 0000000000

I'm trying to get a handle on how to use Ohm's Law to figure out exactly how much signal loss results from a set of RCA's resistance. Most of the info I've found gives values between 10 and 47 kohm for an amp's input impedance. Which should I use? resistance or impedance? Is there even a reactive component I need to worry about?

Sorry, its been 10+ years since my last EE course and I'm a bit fuzzy on the details. If I recall correctly you use the magnitude of impedance((R^2 + X^2)^1/2) as opposed to plain old resistance to use Ohm's Law to determine voltage drop in an A/C circuit.

Just wondering how useful my resistance measurements are since they seem to be a bit lower than the input impedance specs I've seen.

I know. Incredibly nerdy question, but at least its on-topic.



Jonathan? Kiki? anyone?

-Fishy

I suppose it is to keep the output greater than they advertise to give them a good rep. This also gives me a thought about how the regulated amps work. Perhaps they use variable impedance to control the output?

I just remebered something else. The reactive component(X) in an A/C circuit is frequency dependent so the total impedance should change according to frequency. What exactly are these input impedance specs I'm seeing? Seems like since they're not rated at a specific frequency they are most likely purely resistive so I could use my measurements to figure out voltage drop.

Anyone see what I'm getting at?

If I know a source unit's preout voltage, the input impedance of the amplifier, and the combined resistance of an RCA's ground and signal wires I can figure out the the current flowing. Once I got that I can determine the voltage drop across the RCA's and from that figure out what voltage the amp sees.

I know the voltage drop is going to be really small since the amp's input impedance is considerably larger. I'm just curious at what point an RCA's resistance become significant. If it takes a lot then any old crappy set of RCA's should work fine as long as they're shielded properly.

-Fishy

Another interesting benefit of figuring this stuff out would be to determine how useful those fmod dealies would be. Since they are passive filters their cutoff frequencies depend on the resistance of the circuit they're in and this is almost entirely dependent on that pesky amplifier input impedance.

http://www.hlabs.com/technical/crossovers/page2.html

Say I've got ported box tuned to 28 Hz(I do actually :) ) and I need a subsonic filter and am looking at getting an fmod. Normally I'd go for a highpass filter with a cutoff frequency 1/3 an octave below tuning or about 22 Hz. Well the lowest fmod I could get would be a 20 Hz guy, but its actually 25 Hz with a 10 kohm load which is what the 2025 is, but 25 Hz? That fmod is beginning to roll off frequencies nearly at tuning. I know there's not a lot of material recorded this low, but I'm not sure this would help my low end extension much.

But wait, it gets worse, and a lot more complicated as well.

Say I'm using the A2002 in the same sub application and I'm running an old school Alpine 7909 w/o a line driver(read 500mv/.5v preouts) I'm gonna have to run the sensitivity pretty darn high to get enough output. This means the input impedance is going to be LOW, like less than 5 kohms, wait make that 2 kohms. I had the balanced input switch on, hehe. The A2002's input resistance is actually between 1.7 and 4.2 kohms depending on the "gain" with the normal setting. If this is indicative of the actual input impedance of this amp then how does that effect the "20 Hz" fmod's cutoff frequency? If the thing goes from 20 to 25 hz when you go from a 22 kohm impedance to 10k what happened when you drop the load down to 2 kohms? I'm guessing about a 25% increase every time the load is halved or about 40 Hz.

I hope I'm wrong, because a high pass filter with a cutoff frequency of 40 Hz and box tuned to 28 Hz ain't too sporty a combination.

And now the complicated part. If things are working like I believe then whenever I adjust the "gain" on the A2002 I change the input impedance which changes the subsonic cutoff frequency as well! I'm not going to even try to figure that mess out.

I know Harrison claims that "exact crossover frequencies are seldom noticed or necessary" and I'm not sure I've got this input impedance thing figuired right, but still, I'm not likin fmods a whole lot at this point, at least not for a car application.

-Fishy