> exactly how much treble roll off it causes as none of you were offering that detail.
I don't see where the treble response was asked?
IF that is your question, it is easily answered. So sorry you had to simulate it.
I don't see where the treble response was asked?
IF that is your question, it is easily answered. So sorry you had to simulate it.
It isn't a simulation PRR, it's a measurement. I posted it for anyone who was curious of real world results. I'm not trying to disrespect anyone with it. For the record I very much appreciate all of your help and advice on things like this.
I tried several values of R1 keeping R2 as 1k. I used a 4.7k and then a 6.65k in series with a 5k pot for the R1 in the divider and made several measurements from ~12k from R1 max to 4.7 as R1 min. All of those measured the same within a small fraction of a dB so here is the result. Light green trace was with the 8 ohm/1 ohm divider and the pink trace was with 6.65k and 1k:
All of the measurements had around .12dB of rolloff at 20k. Also noticed that the low end below 20Hz had slightly more rolloff than the 8ohm/1ohm divider.
I went with a higher value R1 than 5k because I tested the AVR with a dummy load and a scope and got clean peak voltages of 46V into 8 ohms so I was afraid to rely on a 1/4W 5k pot for that. It turned out that I didn't need to load the power amp on the AVR with a 100 ohm 10W resistor. Distortion numbers were under .1% at normal listening levels. Everything is hooked up and works fine.
I didn't clamp the output with zeners because I don't quite understand how that works yet. I'll have to start a thread about that sometime soon and get some help from you guys.
Thanks again for all the posts guys, I know you get these divider questions frequently.
I tried several values of R1 keeping R2 as 1k. I used a 4.7k and then a 6.65k in series with a 5k pot for the R1 in the divider and made several measurements from ~12k from R1 max to 4.7 as R1 min. All of those measured the same within a small fraction of a dB so here is the result. Light green trace was with the 8 ohm/1 ohm divider and the pink trace was with 6.65k and 1k:
All of the measurements had around .12dB of rolloff at 20k. Also noticed that the low end below 20Hz had slightly more rolloff than the 8ohm/1ohm divider.
I went with a higher value R1 than 5k because I tested the AVR with a dummy load and a scope and got clean peak voltages of 46V into 8 ohms so I was afraid to rely on a 1/4W 5k pot for that. It turned out that I didn't need to load the power amp on the AVR with a 100 ohm 10W resistor. Distortion numbers were under .1% at normal listening levels. Everything is hooked up and works fine.
I didn't clamp the output with zeners because I don't quite understand how that works yet. I'll have to start a thread about that sometime soon and get some help from you guys.
Thanks again for all the posts guys, I know you get these divider questions frequently.
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You never asked for that detail. You also have only just told usshredhead said:
You asked a question about potential dividers, so we answered that question. Maybe you should have asked a question about driving cable capacitance. We would have answered that even without you asking it if you had told us that long cables were involved.
Is there a problem with me posting the data and details of my results? Not sure why I'm getting blowback from this. 😕
In other words if I don't understand or consider every variable in what I'm doing to ask the right questions to everyone, I won't get the answers about it but you'll wait until I find it out on my own through practical experiments and chastise me for it? Well that's kind of a catch 22. What a fun community you guys have here.
How about you explain the math side of things after I post the data and explain what I'm seeing instead of calling me out for something that I might not understand.
In other words if I don't understand or consider every variable in what I'm doing to ask the right questions to everyone, I won't get the answers about it but you'll wait until I find it out on my own through practical experiments and chastise me for it? Well that's kind of a catch 22. What a fun community you guys have here.
How about you explain the math side of things after I post the data and explain what I'm seeing instead of calling me out for something that I might not understand.
You appeared to be complaining that we had not offered information which you had not asked for (frequency response), and for which we had not been given sufficient context (long cables) which would alert us to the fact that you actually did need this information. We were not complaining about your experiments, but the comment accompanying your experiments.
It is the classic problem of the expert talking to the non-expert: if you tell him something he already knows you are accused of being patronising or treating him like an idiot; if you don't tell him something he doesn't know then he complains "how was I supposed to know that?".
The formula you need is f = 1/( 2 pi C R), where R is the output resistance and C is the cable capacitance. This gives the -3dB corner frequency of the low pass filter.
It is the classic problem of the expert talking to the non-expert: if you tell him something he already knows you are accused of being patronising or treating him like an idiot; if you don't tell him something he doesn't know then he complains "how was I supposed to know that?".
The formula you need is f = 1/( 2 pi C R), where R is the output resistance and C is the cable capacitance. This gives the -3dB corner frequency of the low pass filter.
No problem. What often seems to happen in threads is that the initial post doesn't contain enough information and people make assumptions which can result in time being wasted and the resentment that comes with that. This is why I generally start by asking a lot of questions to try and understand what exactly is going on. Ofcourse sometimes this is taken the wrong way, but, such is life.....
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