Mary M S
Screenwriter
- Joined
- Mar 12, 2002
- Messages
- 1,544
I have run my first inept attempts at charting FR. How cool is it to see what you hear!
But not so easy to interpret the results, from my miniscule knowledge base.
Some questions occurred. I ran the first charts noticing a mention made in posts to leave all DSP modes off. To do this I assumed if I ran the test in Stereo, through my pre this avoids the DSP modes. I also ran other graphs various ways: One: Main amp to speakers OFF, hoping this gives me just the sub output, as it is selfpowered.
Ran more in 6-channel bypass and so forth. Although I was not squeaky -clean-careful jotting down my numbers (and was interrupted by people coming and going so I had to start and stop repeatedly. I see enough of a base-line-trend to know I was not far off in taking down and converting the numbers fairly correctly.
Some things jumped out at me, right away. Regarding two graphs run in Stereo mode.
When a total newbie and setting up my pre, I saw the rule of thumb by THX etc for cross-overs to be set at 80hz. However, going only by my own fallible ears, 80 did not sound pleasing in my room so I set my Frnt/Cent/Surrounds at 60/60/100. To me, this sounded better.
When looking at the graph of FR in Stereo mode which should give me my FL/FR and sub. First run I get this.
60/60/100
EDIT: SEE LINK TO GRAPH POST # 9
So I look at the line graph of this and think I have some null? Valleys and peaks, I wonder if switching my crossover will smooth the line. I run it again stereo mode at 80hz for the fronts. Getting wider swings in my peaks and valleys.
EDIT: SEE LINK TO GRAPH POST #9
It appears to me as if I did get a smoother response down the line when my crossover was set at 60 for the FL/FR. When at 80 I get a steep dip bottoming near 71hz. I also see I have some things going on above 100hz, and not sure what to make of that.
By coming back in here yesterday and doing some search functions using different words, I keep running into little bits of information, to add to my whole. I asked what dB I should run the tests at and was told keep it in the 80’s and you should be fine. I erred on the side of caution, (since I have never done this before) and set my meter to read at 70dB. (the level these numbers are based to). I now see doing some more reading that 70db was most likely too low. I was worried about transient spikes knowing the RS meter is not sensitive at certain freq., so I kept the vol. way down. I see from my reading I should bump that level and rerun the tests, but wondered if what I am seeing on these two graphs is what I think it is, crossover related differences?
It seems I have read that rooms often “hump” around 50hz. I see sign of this in these two charts with the hump again much smoother when crossover for mains is at 60. However, when running these tests in other modes, 6-chan analog, PLII etc, the hump with its high centered at 50 has a larger rise .
Any instructions on if I headed the right way. (how I ran the graphs) and what I need to look for.
Looking at the smoother response graph (crossover at 60) I need to be concerned with Freq at 56 and whatever is going on in the 100 to 160 range. Correct?
Any thoughts instruction is greatly appreciated, but will completely understand if those who know, are too bored to tears diagnosing other (call us clueless ) posters trying to make sense of their own graphs!
But not so easy to interpret the results, from my miniscule knowledge base.
Some questions occurred. I ran the first charts noticing a mention made in posts to leave all DSP modes off. To do this I assumed if I ran the test in Stereo, through my pre this avoids the DSP modes. I also ran other graphs various ways: One: Main amp to speakers OFF, hoping this gives me just the sub output, as it is selfpowered.
Ran more in 6-channel bypass and so forth. Although I was not squeaky -clean-careful jotting down my numbers (and was interrupted by people coming and going so I had to start and stop repeatedly. I see enough of a base-line-trend to know I was not far off in taking down and converting the numbers fairly correctly.
Some things jumped out at me, right away. Regarding two graphs run in Stereo mode.
When a total newbie and setting up my pre, I saw the rule of thumb by THX etc for cross-overs to be set at 80hz. However, going only by my own fallible ears, 80 did not sound pleasing in my room so I set my Frnt/Cent/Surrounds at 60/60/100. To me, this sounded better.
When looking at the graph of FR in Stereo mode which should give me my FL/FR and sub. First run I get this.
60/60/100
EDIT: SEE LINK TO GRAPH POST # 9
So I look at the line graph of this and think I have some null? Valleys and peaks, I wonder if switching my crossover will smooth the line. I run it again stereo mode at 80hz for the fronts. Getting wider swings in my peaks and valleys.
EDIT: SEE LINK TO GRAPH POST #9
It appears to me as if I did get a smoother response down the line when my crossover was set at 60 for the FL/FR. When at 80 I get a steep dip bottoming near 71hz. I also see I have some things going on above 100hz, and not sure what to make of that.
By coming back in here yesterday and doing some search functions using different words, I keep running into little bits of information, to add to my whole. I asked what dB I should run the tests at and was told keep it in the 80’s and you should be fine. I erred on the side of caution, (since I have never done this before) and set my meter to read at 70dB. (the level these numbers are based to). I now see doing some more reading that 70db was most likely too low. I was worried about transient spikes knowing the RS meter is not sensitive at certain freq., so I kept the vol. way down. I see from my reading I should bump that level and rerun the tests, but wondered if what I am seeing on these two graphs is what I think it is, crossover related differences?
It seems I have read that rooms often “hump” around 50hz. I see sign of this in these two charts with the hump again much smoother when crossover for mains is at 60. However, when running these tests in other modes, 6-chan analog, PLII etc, the hump with its high centered at 50 has a larger rise .
Any instructions on if I headed the right way. (how I ran the graphs) and what I need to look for.
Looking at the smoother response graph (crossover at 60) I need to be concerned with Freq at 56 and whatever is going on in the 100 to 160 range. Correct?
Any thoughts instruction is greatly appreciated, but will completely understand if those who know, are too bored to tears diagnosing other (call us clueless ) posters trying to make sense of their own graphs!