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post #91 of 115 Old 12-15-2012, 03:33 PM - Thread Starter
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Ok, I will tinker with it some more tonight, but I am still having the hum issues even after trying several different AC lines. Any idea what could be causing the hum? It hums no matter where I plug it into?
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post #92 of 115 Old 12-15-2012, 03:56 PM
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What kind of cables are you using? I use the balanced minidsp between my Denon and EP2500. I was getting a hum until I realized that the XLR-Phoenix adapter I had was mis-wired. I guess the one for the outer sheesh acted as the ground? Once I wire it up properly, problem solved..
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post #93 of 115 Old 12-15-2012, 04:57 PM - Thread Starter
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I am only using an RCA cable.

Also

I have been playing around with the switches, and still get very little output or extension. I currently have only switches 4 and 5 set to on. Is that the correct way? The manual is very confusing on how to set the switches. It says set some to stereo, some to this and some to that, I don't see a stereo option, only on and off?? Can someone please tell me which switches need to be off and which switch should be set to on??
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post #94 of 115 Old 12-15-2012, 06:03 PM
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Set dipswitches:

1 l
2 l
3 r
4 r
5 r
6 l
7 l
8 r
9 l
10 l

l=left
r=right
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post #95 of 115 Old 12-16-2012, 07:14 AM
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Hi Martycool007, your pm replied. Sorry for late reply. I was busy adding iNUke 6000DSP in my setup and doing the fan swap.

I may be wrong in my write up coz of difference of opinion but you can compare it with the advices from other people about correctly setting up the gain on ep4000 and do what you deem best.

Best of luck smile.gif

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post #96 of 115 Old 12-16-2012, 07:33 AM
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Quote:
Originally Posted by Martycool007 View Post

Ok, I will tinker with it some more tonight, but I am still having the hum issues even after trying several different AC lines. Any idea what could be causing the hum? It hums no matter where I plug it into?

FWIW, I added iNuke 6000DSP last night in my system. Just to double check if I was doing wrong. I checked the pre out voltage at reference volume (75dB) keeping sub trim level at 00 (Audyssey and Dynamic EQ off) with 0dBFS 60Hz test tone without any load with and without ART CleanBox Pro. And I felt the need of the bump box in the chain. I always check the voltage at referece volume and trim level at 00 and not +16dB and +12, respectively. Coz those are the max levels I go to. So, I felt the need of bump box.

Now over to you hum issue, I ran into the same hum problem with DIY sub when I removed bump box from the sound chain while adding the inuke. The moment I added bump box, the hum completely went away. And I am using the iNuke on the same power strip that powers denon avr, dvd player, media player, BFD, and a 110 Volt stepdown transformer for iNuke to run. I am not an electrician but I think it may be due to the fact that Behringer amps draw more current from the mains or something else. I never had this humming problem before when I was using Crown XLS 1000 with or without the signal bump box. iNuke is dead silent now on the subwoofer.

Hope that helps.


By the way iNuke 6000dsp rocks big time

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post #97 of 115 Old 12-16-2012, 08:51 AM - Thread Starter
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I have read that link on the previous page about how to determine the subwoofer output voltage and the AVR's maximum clean output voltage, and I just can't follow this crap. I get so confused about half way through reading that. This really sucks because I have ADHD and it makes this stuff very hard to follow. I am honestly so frustrated.

Let me see if I got this right and if not, hopefully someone can help.

Set speakers to large.
Set AVR to stereo.
Set all speakers and subwoofers to maximum level via AVR's menu.
Disable Audyssey
Disconnect all speakers
Turn volume on the AVR to maximum setting
Measure the output of the Left speaker pre-out with a multi-meter. (not sure how to do this? What am I looking for?)
The VOM meter should be set to low AC voltage.
Write down the voltage reading for future reference.
Connect pro-amp to front left speaker pre-out on the AVR.
Reconnect front left speaker to the AVR.
Play a 1khz 0dbfs test tone.
Start with the Behringer amp at the lowest gain possible that still outputs sound.
Slowly increase the volume on the AVR until you hear an overtone, then reduce the volume on the AVR until the overtone goes away.
Do not touch the volume on the AVR now.
Disconnect the Behringer pro-amp.
Now run a 60hz test tone through the AVR and take another voltage measurement from the pre-out on the AVR.
Make a note of this reading and keep the AVR's volume control the same. This reading is your AVR's usable output voltage and this particular volume is the AVR's setting that you need to use when setting the gain structure.

Is all of this correct? What do I do next to measure the sub pre-out voltage? Can a cheap Wal-Mart multi meter be used for this? That is all I have to work with at the moment. Also, any other opinions on the hum issues?
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post #98 of 115 Old 12-16-2012, 09:24 AM
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First of all you don't need to check the Pre out voltage of the main speakers. That Gain Structure article deals with full range signal. It does not deal with 100Hz and below frequencies used for subwoofer. You only do it for the subwoofer channel coz you are adding the pro sub for subwoofer duty only. There is only one EXCEPTION to that procedure. That article tells you to set the channel levels to max and same goes for the volume. I humbly differ with setting the speaker levels and master volume to max position for a very valid reason. It is because I never ever would like to listen to music or watch movies with master volume at +18dB and speaker (subwoofer) level at +12 in avr. Even if the avr is pumping out 1000000000 volts at that level; it is immaterial for me. I know checking the output voltage at maxed out level is done to know the maximum dynamic range of the system before CLIPPING. But I think checking the output voltage at 00 trim level at your REFERENCE max volume (It could be any and not necessarily 00 on the master dial) is far more practical. I am more concerned about the pre out voltage at 00 subwoofer trim level and at MY REFERENCE volume, which is not 00 on the master dial BUT it still reads 75dB at my listening position.

I have already sent you a pm. check that.

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post #99 of 115 Old 12-16-2012, 09:57 AM
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Marty-
I feel your fustration! Do you have a bump box to try? I'll send you my clean box if you'd like.
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post #100 of 115 Old 12-16-2012, 11:04 AM
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Quote:
Originally Posted by braveheart123 View Post

First of all you don't need to check the Pre out voltage of the main speakers. That Gain Structure article deals with full range signal. It does not deal with 100Hz and below frequencies used for subwoofer. You only do it for the subwoofer channel coz you are adding the pro sub for subwoofer duty only. There is only one EXCEPTION to that procedure. That article tells you to set the channel levels to max and same goes for the volume. I humbly differ with setting the speaker levels and master volume to max position for a very valid reason. It is because I never ever would like to listen to music or watch movies with master volume at +18dB and speaker (subwoofer) level at +12 in avr. Even if the avr is pumping out 1000000000 volts at that level; it is immaterial for me. I know checking the output voltage at maxed out level is done to know the maximum dynamic range of the system before CLIPPING. But I think checking the output voltage at 00 trim level at your REFERENCE max volume (It could be any and not necessarily 00 on the master dial) is far more practical. I am more concerned about the pre out voltage at 00 subwoofer trim level and at MY REFERENCE volume, which is not 00 on the master dial BUT it still reads 75dB at my listening position.

I have already sent you a pm. check that.

False.

You set everything to max so that no matter what you feed the system(source material) the system can never clip throughout the entire signal chain. Your suggestions on deviation from the instructions in that post are false assumptions which do the OP a disservice and may cause damage to his hardware. You have no way to control the output voltages on preouts, they are relative to the source signal. The only way to ensure the pre out voltages stay below the max input sensitivity of the amp is set the gain structure so that its not possible for the AVR to clip the amp no matter what the input signal.
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post #101 of 115 Old 12-16-2012, 05:45 PM - Thread Starter
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Where can I find a test tone, or sine wave generator DVD? I would prefer to have the actual hard-disk, rather than a downloaded one, mostly because I currently only have an iPad, and no regular PC until later in Janurary.

Another question that I have is when testing to see what the AVR's maximum output voltage is, when playing a 1khz sine wave signal and increasing the volume on my AVR until I hear an overtone, then slowly reduce the volume on the AVR until the overtone goes away... my question is how do I know when the sub is playing an overtone? What is an overtone anyway, and how does a sub output an overtone?
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post #102 of 115 Old 12-16-2012, 07:29 PM
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Overtone? I would assume you might be thinking over a 2nd or 3rd harmonic? Also, post over in the audio theory thread where the test DVD sticky is and see if anyone might offer to burn it for you. I had a guy do this for me as I dont have a burner and I just slid him some coin for the cost of mailing and the disc smile.gif

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post #103 of 115 Old 12-16-2012, 07:56 PM
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Quote:
Originally Posted by Martycool007 View Post

Is all of this correct? What do I do next to measure the sub pre-out voltage? Can a cheap Wal-Mart multi meter be used for this? That is all I have to work with at the moment. Also, any other opinions on the hum issues?
You really should use a True RMS meter. They don't tend to be real cheap.

However, the instructions you posted aren't terribly applicable to a subwoofer.
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post #104 of 115 Old 12-16-2012, 10:26 PM
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Quote:
Originally Posted by NicksHitachi View Post


You set everything to max so that no matter what you feed the system(source material) the system can never clip throughout the entire signal chain.

Yes you are absolutely right....but doing so yeilds nothing at all at least sonically. I checked it the first time i went pro way and checked it again thinking I may be wrong. All the oomph ebbs away from the sub response based on your anecdotal preconception. In reality preout voltage is way low at 00 master volume and trim level, which does require a signal booster. If at all not using signal booster served any purpose, I'd not have used it. Stop feeding myths to OP and feed him useful info based on actual experience with gain matching. No wonder sound is so subjective.
Quote:
Your suggestions on deviation from the instructions in that post are false assumptions which do the OP a disservice and may cause damage to his hardware.

Investigate/experiment and then resort to blanket refutation if required.

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post #105 of 115 Old 12-17-2012, 06:27 AM
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Quote:
Originally Posted by Martycool007 View Post

I have read that link on the previous page about how to determine the subwoofer output voltage and the AVR's maximum clean output voltage, and I just can't follow this crap. I get so confused about half way through reading that. This really sucks because I have ADHD and it makes this stuff very hard to follow. I am honestly so frustrated.

Let me see if I got this right and if not, hopefully someone can help.

Set speakers to large.
Set AVR to stereo.
Set all speakers and subwoofers to maximum level via AVR's menu.
Disable Audyssey
Disconnect all speakers
Turn volume on the AVR to maximum setting
Measure the output of the Left speaker pre-out with a multi-meter. (not sure how to do this? What am I looking for?)
The VOM meter should be set to low AC voltage.
Write down the voltage reading for future reference.
Connect pro-amp to front left speaker pre-out on the AVR.
Reconnect front left speaker to the AVR.
Play a 1khz 0dbfs test tone.
Start with the Behringer amp at the lowest gain possible that still outputs sound.
Slowly increase the volume on the AVR until you hear an overtone, then reduce the volume on the AVR until the overtone goes away.
Do not touch the volume on the AVR now.
Disconnect the Behringer pro-amp.
Now run a 60hz test tone through the AVR and take another voltage measurement from the pre-out on the AVR.
Make a note of this reading and keep the AVR's volume control the same. This reading is your AVR's usable output voltage and this particular volume is the AVR's setting that you need to use when setting the gain structure.

Is all of this correct? What do I do next to measure the sub pre-out voltage? Can a cheap Wal-Mart multi meter be used for this? That is all I have to work with at the moment. Also, any other opinions on the hum issues?


OK, lets back up and regroup for you now.

I'm not even going to address anymore why the aforementioned post is accurate, Its co-authors are well known experts(Ricci, AX9, and BruceK).

I'll try to give a cliff notes version(somebody will correct me if I mis-speak the post im sure).

Setting everyting to Max(see post) and measuring preout voltage at all max settings tells you this:

1. Your AVRs max pre out voltage for that output.
2. From that max voltage you will know if your AVR can fully drive your pro amp(see your proamp manual for input sensitivity).

Now the overtones stuff is merely clipping detection and introduction of harmonics as beast suggested. However the post says ignore that for subs and subtract ~30% from your max preout voltage. This is your max clean avr preout voltage for the sub preout. Turn down master volume on AVR until you read your max clean avr preout voltage(Max voltage -30%) on multimeter. Note this Maxter Volume setting.

Now(refer to post) connect amp, turn AVR master volume back to same setting you noted before and slowly turn up "gain" knob(s) on pro amp until you light the clip lights solid.

Thats it. Don't touch the gain knobs on your pro amp, it is now set to clip at the same voltage as the AVR preout. You can lower gains, trims, whatever you want in the AVR and the AVR and pro-amp will clip together at same voltage. Obviously you want to keep the clip lights out altogether during program material but thats another issue altogether.
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post #106 of 115 Old 12-17-2012, 06:17 PM
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You can't really determine max clean output looking at a multimeter alone. That 30% rule of thumb is convoluted. The measured RMS voltage will continue to increase even while the waveform is clipped. The meter is reporting a correct reading. The RMS voltage is still increasing, but the peak voltage amplitude is not. You want to determine where the output starts to clip. If you only have a multimeter you need to compare the increase in measured RMS voltage vs. the increase in the receiver's volume. When clipping starts a 1dB increase in the receiver's volume will not correlate to a 1dB increase in the RMS voltage read by the meter. If you record a variety of readings and use Excel or a calculator you can find the point. To calculate the Vrms dB increase take 20*log(Voltage Gain). So you take the new Vrms reading and divide it by the previous Vrms reading to get voltage gain.

Here's an example from my receiver:



This suggests that clipping starts at 0.5dB and the max clean output is at -0.5dB. I can confirm from visually looking at the waveform with an oscilloscope that this is correct. The -0.5dB waveform is not clipped and the 0.5dB waveform is clipped. Here's the proof.

-0.5dB waveform:


0.5dB waveform:



I hope this helps.

Edit: Adding for the formula to generate voltage gain in dB.
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post #107 of 115 Old 12-18-2012, 04:10 AM
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I do see your point illustrated with the oscope. however most people dont have an oscope to determine clean output.

Really, though issues you have with that post dont have a place here IMO even though you might be correct. The post is mostly accurate although there is a lot of conservatism built in to make it easy for beginners. Author a better more accurate post for newbs doing gain structure and ill gladly use yours as reference.... wink.gif

I just dont understand fully your suggestion, please author a full writeup so i can understand. The OP prob doesnt need this level of detail, but idk maybe....
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post #108 of 115 Old 12-18-2012, 05:48 AM
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Quote:
Originally Posted by NicksHitachi View Post

I do see your point illustrated with the oscope. however most people dont have an oscope to determine clean output.
Which is precisely why I gave instructions and a method for determining where clipping starts without an oscilloscope using only a True RMS multimeter and some math. I just used the scope to show that the method was indeed correct.
Quote:
The goal is to get everything to clip together(approximately) and to maximize the equipments dynamic range. Im not sure you could get any closer to max clean output with your " doesnt get any louder as voltage increases" method since clipping and distortion can be louder than the fundamental sound? Additionally louder is measured by 1db which requires an increase of 33% power right? Hows that get us closer than 30% since the unit of measure(1db) resolution is 33% at full power?
My method wasn't one of finding where it doesn't get any louder. My method more accurately finds the "volume" where the voltage output goes non linear due to clipping. This is what the guide you're referenced is after. Its method is just less precise.
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post #109 of 115 Old 12-18-2012, 06:38 AM - Thread Starter
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So now I can finally wrap my head around this stuff, it is all starting to make since.

The big issue that I need to tackle now, is trying to figure out why I am getting so much of a hum from my woofer. I have tried many different outlets, and they are all the same. I have tried using different power cords, and the hum remains. Is it possible that something is wrong with my amp?
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post #110 of 115 Old 12-18-2012, 06:52 AM
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Quote:
Originally Posted by Stereodude View Post

Quote:
The goal is to get everything to clip together(approximately) and to maximize the equipments dynamic range. Im not sure you could get any closer to max clean output with your " doesnt get any louder as voltage increases" method since clipping and distortion can be louder than the fundamental sound? Additionally louder is measured by 1db which requires an increase of 33% power right? Hows that get us closer than 30% since the unit of measure(1db) resolution is 33% at full power?
My method wasn't one of finding where it doesn't get any louder. My method more accurately finds the "volume" where the voltage output goes non linear due to clipping. This is what the guide you're referenced is after. Its method is just less precise.

Aha, yes I re-read your post, better understood and edited my response as you were responding..... I do see what you mean and your method could be much more precise.

You should write up your method I would love to read it.
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post #111 of 115 Old 12-18-2012, 07:02 AM
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Quote:
Originally Posted by Martycool007 View Post

So now I can finally wrap my head around this stuff, it is all starting to make since.

The big issue that I need to tackle now, is trying to figure out why I am getting so much of a hum from my woofer. I have tried many different outlets, and they are all the same. I have tried using different power cords, and the hum remains. Is it possible that something is wrong with my amp?

  • Is it ground loop? Does amp humm without signal cable(RCA/XLR) attached to amp?
  • If hum goes away without signal cable attached, its likely GL hum.
  • If it is GL hum, start with removing Coax from cable/dish and see if hum goes away.
  • IF not dish or cable start removing components from your system one by one until hum goes away.
  • Once component is isolated solution may depend on what type of component it is.


Assume its ground loop until you can rule it out. Isolate the source of the loop and then you can look at solutions to break it.
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post #112 of 115 Old 12-18-2012, 09:00 AM
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Quote:
Originally Posted by Martycool007 View Post

So now I can finally wrap my head around this stuff, it is all starting to make since.

Told ya it wasn't rocket science smile.gif

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post #113 of 115 Old 12-18-2012, 06:20 PM - Thread Starter
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Ok, when the RCA to 1/4 TRS cable is unplugged the hum does indeed go away. I have tried disconnecting the cable box, to no avail. What comes after finding the component that is causing the ground loop?
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post #114 of 115 Old 12-18-2012, 07:05 PM
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Quote:
Originally Posted by Martycool007 View Post

Ok, when the RCA to 1/4 TRS cable is unplugged the hum does indeed go away. I have tried disconnecting the cable box, to no avail. What comes after finding the component that is causing the ground loop?

Tried replacing the cable? Could be mis-wired underneath the sheathing.
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post #115 of 115 Old 12-19-2012, 07:19 AM
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Originally Posted by Martycool007 View Post

Ok, when the RCA to 1/4 TRS cable is unplugged the hum does indeed go away. I have tried disconnecting the cable box, to no avail. What comes after finding the component that is causing the ground loop?

Depends on the component as to the solution.

Try unplugging HDMI cables now one by one and see if you can isolate it that way. I've had ground loop over hdmi cables be a pain too on poorly grounded components.

The cable might be a good thing to replace too. I like XLR cables to connect to the amp they are much more secure and people have reported better results against ground loop hum. IDK how, why, or if the XLR is better but I do like them better.

A "cheater plug" will tell you right away if its ground loop, but its not a permanent solution and you still have to isolate it to fix it. If you put one of these on the amp and the hum goes away, its 99.999999% ground loop. Now you can operate it without the earth ground but if you have an internal short to the chassis, it will be live with mains volatage when you touch it.............eek.gif

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