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Discussion Starter #61
seems I used an old power cable from a refrigerator or appliance and just wired the ground to the chassis of the receiver. I did scuff the paint a tiny bit to get to bare metal. Then I plugged it into the power strip I was using for everything and viola no more hum for me. I think I pulled one or both of the spades on the plug so I had no power going through it.
Thanks @dpdpdp. That is super helpful to say the least. Do you by any chance have a picture of how you terminated the other end? That would help me figure it out without risking an electric hazard. Thanks again!
 

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Discussion Starter #62 (Edited)
Which MiniDSP did you order? IMHO, the only one you should be ordering at this point is the 2x4HD. It is obvious to me (though people will argue til they could be part of the Blue Man Group), that you do not have enough voltage from your Yamaha sub out RCA. Many people have experienced this, myself included. Pro gear runs at +4dBV, and consumer gear runs at -10dBm. These are two different scales and cannot be equated directly, which is what I feel some people misunderstand.

The Crown 0.775V setting does make a difference, but it is DEFINITELY not adequate for the lack of voltage output from your Yamaha. You will also notice that the hum is louder on the 0.775V setting than the 1.4V. I run an XLS 1502, and for awhile it was my subwoofer amplifier. I needed an ART Cleanbox Pro to get my input signal high enough to drive the Crown into the clipping zone. I ran my sub trim all the way up on my Marantz (without the CB Pro) and barely saw the first light on the Crown. I was not running a high pass filter though, so I would not recommend the CB Pro for your situation. Going back to the hum - I initially set the Crown on the 0.775V and there was noticeable hum. Setting it to 1.4V and turning up the Cleanbox to compensate did not produce the same level of hum, and I was hitting the clip indicator at the same volume level on the AVR while playing the same demo scenes. I can't tell you why on that one - compensation with the CB Pro should return the same hum level, but it didn't. In order to get approximately the same hum, the CB Pro needed to be up quite a bit more, and I hit the clip light at a much lower AVR volume level. Just my experience.

I do not have experience with the standard MiniDSP 2x4, but I have dealt with the Balanced and 2x4HD. The Balanced output voltage is 'probably' adequate for driving the Crown. I say 'probably' because I still feel you may need more to drive the Crown to 'tickling' the clip indicator. The 2x4HD however, has voltage output in spades. When I switched from the Crown XLS 1502 to a QSC PLX 3002, I still needed the Cleanbox in the signal chain. I now have a 2x4HD. I had to bump the gain up on the HD to get the same output as the CB Pro (4.5dB on the input, 4.5dB on the output. +9dB total), but there is PLENTY left in the tank if I needed more voltage to the sub amp.

I feel I must also add that I usually run my amp attenuation knobs (usually labeled 'gain', a misnomer) at about 25% from full (at 75%). This is because I like to have some knob control when listening to music. If I feel a particular track could use some reinforcement, I use the amp knobs to adjust to taste. It's my listening session, I don't really care how the 'mixing professional' wanted it to sound - I know how I want it to sound and what makes me happy.


Edit: Had to clarify where I run my amp knobs at - I run them at 75% (at about the 3'oclock position).
Thanks for the detailed explanation @drewp29. I did order the minidsp 2x4HD. Does that mean that I would not require CB Pro to drive sub RCA output higher and minidsp should be able to take care of that? Please advise.
 

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Thanks for the detailed explanation @drewp29 . I did order the minidsp 2x4HD. Does that mean that I would not require CB Pro to drive sub RCA output higher and minidsp should be able to take care of that? Please advise.

You should be fine with the 2x4HD. You'll need to adjust the gain up in the MiniDSP program, but it should have no issues outputting enough voltage to drive the Crown.


Edit: I initially set my gains up as +12dB overall (split between input and output gain), and it sent my amps into clipping at a lot lower AVR volume level. Like 6-8 volume steps lower. I lowered it to +9dB overall gain and it seemed like a happy median. I actually dialed back the knobs on my amplifier a couple clicks (used to have it at +28dB gain on amp knob, now I keep it at +26dB gain), so I could probably lower it even a little more if I needed. Honestly, if I maxed out the amplifier knobs, I could probably get away with no gain in the MiniDSP, or possible only 2-3dB to get the same output from the amp at the volume levels I am used to.
 

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Discussion Starter #64
You should be fine with the 2x4HD. You'll need to adjust the gain up in the MiniDSP program, but it should have no issues outputting enough voltage to drive the Crown.


Edit: I initially set my gains up as +12dB overall (split between input and output gain), and it sent my amps into clipping at a lot lower AVR volume level. Like 6-8 volume steps lower. I lowered it to +9dB overall gain and it seemed like a happy median. I actually dialed back the knobs on my amplifier a couple clicks (used to have it at +28dB gain on amp knob, now I keep it at +26dB gain), so I could probably lower it even a little more if I needed. Honestly, if I maxed out the amplifier knobs, I could probably get away with no gain in the MiniDSP, or possible only 2-3dB to get the same output from the amp at the volume levels I am used to.
That gives me hope @drewp29. Thanks a lot and I look forward to your continued help once I get the minidsp delivered.
 

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I read the topic and immediately thought of the track on pirates of the Caribbean.

Check out at wits end soundtrack. Its probably one of my favorite tracks for the movie series.



Sent from my SM-G950U using Tapatalk
 

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Discussion Starter #66
I read the topic and immediately thought of the track on pirates of the Caribbean.

Check out at wits end soundtrack. Its probably one of my favorite tracks for the movie series.



Sent from my SM-G950U using Tapatalk
hahaha, that is the movie that got me into the whole HT scene. There is nothing better than the first 2 installments of the franchise. Its been a crazy work day and I have not been able to step into my HT to start implementing all that's suggested so far. Hopefully will get to it in a couple of hours.
 

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Discussion Starter #67
Update:

Finally got to do some testing. Channel 1 gain knob on Crown set to max;

1) Crown xls 2502 connected to DEV with RCA in channel 1 input and nothing else connected - Silent, no hum

2) Crown connected to DEV with RCA connected to channel 1 input and subwoofer output on Yamaha RX A2000 with no power connected to Yamaha - Slight humming noise.

3) Crown connected to DEV with RCA connected to both crown and Yamaha AND HDMI connected from PS3 to Yamaha with Yamaha not connected to power - Slight humming noise

4) Crown connected to DEV with RCA connected to both crown and Yamaha AND HDMI connected from PS3 to Yamaha WITH Yamaha connected to power but power in standby - Elevated humming noise

5) Crown connected to DEV with RCA connected to both crown and Yamaha AND HDMI connected from PS3 to Yamaha WITH Yamaha connected to power with power on - Elevated humming noise

6) All remaining same as in #5 AND HDMI from receiver to projector connected to output one WITH projector power cable connected to outlet- High humming noise

7) 6) All remaining same as in #6 AND HDMI from receiver to projector connected to output one WITH projector power cable Disconnected from outlet- humming noise back to the same level as in #5

I am just baffled at what to do. Any suggestions?
 

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Subwoofers are way more important than PS3's. Or TV's. Music only system time!

You've been given good advice for solving ground loop issues. Try that stuff first.

Edit: you didn't try the yamaha powered but the hdmi unconnected.
 

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Discussion Starter #69
Is there an HDMI device connected to the Yamaha when it is unplugged from the wall and still humming? HDMI has a ground and can cause loops if the HDMI device is also grounded. Unplug all the HDMI devices to see if the hum stops. If it does stop reintroduce HDMI devices one at a time. You can get optical HDMI cables if it is an HDMI device causing the issue, but they are not the most cost effective solution.

I have around 5 devices in my current setup, any of which can cause a ground loop. Pay attention to things that use three prong outlets. Current can flow between those devices, usually that is not a problem until you introduce a grounded power amp.

It seems like HDMI from the receiver to projector adds to the humming noise when plugged in especially when the projector is plugged in the outlet as well. If projector is unplugged, humming noise goes done quite a bit. What can I do to resolve this. Will adding a Jensen isomax will help?
 

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Discussion Starter #70 (Edited)
On sub settings I upped the level to +10 db. Noticed that under Parametric EQ section, Yamaha has the sub at :

Band #1
Gain: 0.0db
Frequency: 31.3Hz
Q: 1.000

Do I need to change that in any way?

In addition, I set the sub level at +10db, removed HPF, set crown amp in bridge mode and senstivity set to .775, I am still getting just one indicator light at the amp. I am lost here....
 

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Discussion Starter #71
Subwoofers are way more important than PS3's. Or TV's. Music only system time!

You've been given good advice for solving ground loop issues. Try that stuff first.

Edit: you didn't try the yamaha powered but the hdmi unconnected.
Tried that scenario just now and humming is there but not as high as when HDMI from projector to receiver is connected. Any suggestions as to how to solve this problem?
 

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To solve the ground loop problem? or the gain problem?

Ground loop, try an isolator first. "cheater plug". See if it helps.

Gain: might just need a cleanbox if the Yamaha doesn't want to output enough signal.

In the mean time, that 31hz eq gain... crank it up, see what happens. Keep Q low, 1 or less than 1 is a broad rise.

Chris
 

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Discussion Starter #73
To solve the ground loop problem? or the gain problem?

Ground loop, try an isolator first. "cheater plug". See if it helps.

Gain: might just need a cleanbox if the Yamaha doesn't want to output enough signal.

In the mean time, that 31hz eq gain... crank it up, see what happens. Keep Q low, 1 or less than 1 is a broad rise.

Chris
In addition, I set the sub level at +10db, removed HPF, set crown amp in bridge mode and senstivity set to .775, I am still getting just one indicator light at the amp. I am lost here....
 

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Do you have all your equipment plugged into the same circuit?
I would try — get a power strip and plug ALL equipment into the one power strip including your projector even if that means running an extension cord. Once you know they are all on the same circuit you should no longer have a POWER GROUND LOOP. If the noise is still there then disconnect interconnects one at a time, change any problem cables found. I would also add a ground wire from your amp to your AVR.
 

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Nah, it just means you need a cleanbox for that yamaha for whatever reason. Some AVR's output lame sub signals.

Order up one of those, they're cheap, or a minidsp 2x4HD can definitely drive a 2502 to clipping no problem(done it personally) and is powerful eq capability.

Order those parts, concentrate on your hum problem for now.

The dev will chew up your old 10" sub and spit it out. It's a lot of output. It's really not a concern. You'll be displacing several times more air. Once it gets set up right you'll laugh at your concerns....

Chris
 

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Tried that scenario just now and humming is there but not as high as when HDMI from projector to receiver is connected. Any suggestions as to how to solve this problem?
How many prongs are on that projector cord? Current is probably flowing from the projectors ground over the HDMI, through the receiver and then over the RCA cable ground to the XLS. In this scenario a wire would need to be bound to projector (hopefully it has a grounding terminal) and then bound to the XLS. The trickle current should mostly go over the wire vs the HDMI and RCA cables due to them having a higher impedance.
 

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Discussion Starter #77 (Edited)
How many prongs are on that projector cord? Current is probably flowing from the projectors ground over the HDMI, through the receiver and then over the RCA cable ground to the XLS. In this scenario a wire would need to be bound to projector (hopefully it has a grounding terminal) and then bound to the XLS. The trickle current should mostly go over the wire vs the HDMI and RCA cables due to them having a higher impedance.
Hi John, projector has a 3 prong power cable. Projector is on its own circuit and rest of the AVR equipment is on its own circuit. Do I need to hire an electrician to fix this ground loop issue? Its just driving me nuts.
 

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Discussion Starter #78
Nah, it just means you need a cleanbox for that yamaha for whatever reason. Some AVR's output lame sub signals.

Order up one of those, they're cheap, or a minidsp 2x4HD can definitely drive a 2502 to clipping no problem(done it personally) and is powerful eq capability.

Order those parts, concentrate on your hum problem for now.

The dev will chew up your old 10" sub and spit it out. It's a lot of output. It's really not a concern. You'll be displacing several times more air. Once it gets set up right you'll laugh at your concerns....

Chris
I do have the minidsp on order and should receive it by Monday. I am guessing that I would not need a Clearbox in that case, correct? Should I hire an electrician to fix this ground loop issue? I am not sure what to do.
 

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Hi John, projector has a 3 prong power cable. Projector is on its own circuit and rest of the AVR equipment is on its own circuit.
Circuits do not matter with ground current from my experience, that is your main culprit with the projector. If you want to fire it up right away, grounding the projector and the amp together should lower the noise floor. If you can wait for the MiniDSP that very well could fix your issue. It would very likely drop the ground somewhere between the input and outputs. I cannot find a picture of the power supply that comes with the DSP. It would more than likely break the ground path on the RCA side which fixes your humming issue if it uses a two prong power supply.
 

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Discussion Starter #80 (Edited)
Circuits do not matter with ground current from my experience, that is your main culprit with the projector. If you want to fire it up right away, grounding the projector and the amp together should lower the noise floor. If you can wait for the MiniDSP that very well could fix your issue. It would very likely drop the ground somewhere between the input and outputs. I cannot find a picture of the power supply that comes with the DSP. It would more than likely break the ground path on the RCA side which fixes your humming issue.
Ok, in that case I will wait for the minidsp to come in. Will that also eliminate the need for CleanBox as well? I was looking at https://www.bhphotovideo.com/c/product/1344649-REG/jensen_transformers_ci_2rr_line_input_isolator_stereo.html Do you think this will be of any help?
I think minidsp has a prong power adapter ( https://www.amazon.com/miniDSP-2x4-Regulated-Power-Supply/dp/B01N4GDXLU) Will this be helpful to break ground loop?
 
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