ginmtb
Junior Member
Posts: 74
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Post by ginmtb on Dec 9, 2006 0:59:34 GMT -7
Well sonova... the 30hz low cut filters were switched to "ON". They did a nice job gol dang it, didn't they? I feel oh so lame. One little dip switch (and one big dip). Now let the testing re-begin... You are the man Thomas...
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ginmtb
Junior Member
Posts: 74
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Post by ginmtb on Dec 9, 2006 2:26:00 GMT -7
Okay, one test and now I've got to get to sleep... Here is the nearfield measurement: No EQ. No REW. Through receiver with 80hz crossover. Seems like output above 80hz is still high, but it does drop off fairly rapidly. Finally some output below 30hz. Man, still shaking my head about that dip switch.
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Post by ThomasW on Dec 9, 2006 9:33:10 GMT -7
You need to recheck all the filter setting switches. And understand what those switches do
There are 2 switches that toggle between 30Hz or 50Hz, and 2 more switches that toggle the filters themselves on/off
The 2 switches labeled "Low Cut Filter" need to be in the "Off" position.
Sometimes the on/off indicators on the "Low Cut Filter" switch itself are wrong. So change the postion of how you currently have them placed and take another set of measurements.
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ginmtb
Junior Member
Posts: 74
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Post by ginmtb on Dec 9, 2006 11:20:55 GMT -7
Yeah, I saw that last night (or this morning). The two switches labeled "low cut filter" are in the off position. The previous graphs were done with them in the on position - hence the big drop off at 30hz. So I'm sure they are correct now, as I'm actually getting more appreciable measurements below 30hz.
I'll do some more testing now at the listening area and then from different points in the room.
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ginmtb
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Posts: 74
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Post by ginmtb on Dec 9, 2006 12:02:27 GMT -7
Okay, here are the measurements from the seated position: Not great, but a little bit better than my original at the lower frequencies: Now I'll goof around with the BFD... Mike
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ginmtb
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Posts: 74
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Post by ginmtb on Dec 9, 2006 12:33:19 GMT -7
Okay, here it is with the BFD settings: I think this thing is finally starting to look like an IB. What do you think?
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Post by ThomasW on Dec 9, 2006 14:32:07 GMT -7
I think this thing is finally starting to look like an IB. What do you think? I think the before EQ plot looks like there's a 30Hz filter roll-off in the signal path. The output of a driver with a ~28Hz Fs doesn't drop like a rock below that frequency. The roll-off below Fs should be 12dB/octave. You've got 20+dB/octave roll-off. So somethings not right. Whatever the current setting for the 2 Low Cut Filters dip switches is, move them the other direction and remeasure. And why is there output to 160Hz? Are you taking these measurements with the main speaker operating? If so turn them off. Is there EQ in the receiver? if so make sure it's turned off, and that there are no low frequency filters turned on in the receiver
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peted
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Posts: 81
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Post by peted on Dec 9, 2006 15:44:51 GMT -7
Hey Thomas and ginmtb. I also get some output at 160Hz. Working through integrating my sub with my mains, I discovered that my H/K 235 has a -12dB/octave second order rolloff for the sub crossover (I determined this by measurements using my BFD LEDs to gauge signal strength and confirmed with Tech Support for H/K), rather than the -24dB/octave rolloff that many processors use. Not sure why Harman Kardon does this, but depending on the receiver's rolloff that ginmtb is using, maybe it has a -12db/octave crossover...
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Post by ThomasW on Dec 9, 2006 16:21:03 GMT -7
If there was a 2nd order filter in the receiver, there wouldn't be a +10dB spike at 100Hz
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ginmtb
Junior Member
Posts: 74
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Post by ginmtb on Dec 9, 2006 16:25:49 GMT -7
I think this thing is finally starting to look like an IB. What do you think? I think the before EQ plot looks like there's a 30Hz filter roll-off in the signal path. The output of a driver with a ~28Hz Fs doesn't drop like a rock below that frequency. The roll-off below Fs should be 12dB/octave. You've got 20+dB/octave roll-off. So somethings not right. Whatever the current setting for the 2 Low Cut Filters dip switches is, move them the other direction and remeasure. And why is there output to 160Hz? Are you taking these measurements with the main speaker operating? If so turn them off. Is there EQ in the receiver? if so make sure it's turned off, and that there are no low frequency filters turned on in the receiver Okay, I'll try it - but it sure seems like the performance is MUCH better now with my current setup. Only the subwoofer was connected when I did these measurements BTW. I have the Yamaha RX-V2700 receiver. I'll have to check and see what the crossover specs are. Not sure if 12db or 24db.
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ginmtb
Junior Member
Posts: 74
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Post by ginmtb on Dec 9, 2006 23:00:26 GMT -7
Well my receiver has a 24db crossover slope. So I gotta see what's going on there. It has an automatic setup function, so perhaps something weird happened to the frequency response because of that. I'll try to reset the subwoofer output...
Mike
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ginmtb
Junior Member
Posts: 74
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Post by ginmtb on Dec 10, 2006 1:56:09 GMT -7
Okay, this is strange - I reset the crossover to 80hz, however it seems to be stuck at 160hz from the YPAO setup procedure. I can't seem to manually change it to 80hz. So this explains the higher response above 80hz. I'll have to contact Yamaha on this one as the manual doesn't provide much help. Or post in AVSForum for help. Now I haven't solved the drop off from 30hz. One of the tests I did was to change the dip switch for the low cut frequency to 50hz. When I did this the graph didn't change - so I believe I'm safe to assume that the low cut filters are off. The low end has substantially improved since I turned the filters off. Is it possible that I have a significant room gain from 30-63hz? Some day I hope to get this thing setup properly...
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Post by ThomasW on Dec 10, 2006 8:35:37 GMT -7
Again, we're not concerned with the position of the 30Hz-50Hz (#2 & #9) DIP swtiches. We are only concerned with whether DIP switches (#3 & #8) are turned off. On some amps these are mismarked so it's important to try the switches in both on/off postions to see which is actually off. For most people I think it's a good idea to turn off the clip limiter DIP switches = #1 & #10
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ginmtb
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Posts: 74
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Post by ginmtb on Dec 10, 2006 13:12:08 GMT -7
I am aware of that - I was just noting that when I switched the frequency switch it did nothing to the signal. And actually, during the initial measurement with the low freq filter "on" it was set to 50hz. But I will flip the switches to absolutely 100% rule out any issues with that filter.
I will turn off the clip limiters also.
Thanks!
Mike
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Post by chrisbee on Dec 11, 2006 1:21:35 GMT -7
If the filters are set to off with 3 & 8 then switching the filter frequency should have no effect at all.
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ginmtb
Junior Member
Posts: 74
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Post by ginmtb on Dec 11, 2006 8:56:29 GMT -7
Thanks for putting into clear words for me. That is the point I was trying to make. I'll still do some switching of the dip switches to rule everything out.
Mike
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Post by titch on Dec 11, 2006 15:07:31 GMT -7
Turning off the clip limiter switches, just keeps the red light from turning on, right? So why do people do that? Dont you want to see if that light comes on?
thx
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Post by ThomasW on Dec 11, 2006 16:15:42 GMT -7
Turning off the clip limiter switches, just keeps the red light from turning on, right? So why do people do that? Dont you want to see if that light comes on? thx The amp has clip limiters. Turning the switches off turns off the limiters. The clip indicator lights function whether the limiters are on or off.
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Post by ThomasW on Dec 11, 2006 16:22:44 GMT -7
If the filters are set to off with 3 & 8 then switching the filter frequency should have no effect at all. Correct, the source of confusion (and problems in the past) is that on certain amps there are on/off indicators molded into the plastic on the DIP switches. And those indicators refer to positions that are opposite what is shown on the graphics printed on the back of the amp and in the manual. So it's best to check if what's indicated as "off" really is....
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ginmtb
Junior Member
Posts: 74
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Post by ginmtb on Dec 12, 2006 0:05:19 GMT -7
Okay, I did some more testing tonight. This time, I ran the sine waves direct from my analog out on my DVD player to the subwoofer. Whoa, had to crank the gain waaaaaaay down on the EP1500. But no more weird crossovers or anything. Just straight signal. Here are my results: I think it is obvious which one has the low frequency filter on and which one doesn't. Amazing the response past the 89hz mark. The clip limiter switches are off in both cases. I actually had set the low frequency filter to the 50hz setting to get the most dramatic effect of the on-off dip switches. I'm beginning to think this equalized setting is pretty good: Still need to figure out though how to deal with the high crossover point on my receiver. I've sent an e-mail to Yamaha and have posted in AVSForums. Haven't heard back from Yamaha and haven't gotten the definitive answer at AVSForums.
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