Audible Hissing from the Speakers, is it a norm?? - AVS Forum
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post #1 of 18 Old 05-15-2013, 05:36 AM - Thread Starter
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Many of us experienced hissing during the system idling time with no material playing. Can this be a norm for all the high gain amplifier? Or high power amplifier? Or high efficient speakers? Or it's wrong combo of cables or possible of faulty preamp??

Thrash your opinion and solutions here if there's any. All feedback is welcomed!!
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post #2 of 18 Old 05-15-2013, 05:41 AM
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To help isolate:

Disconnect all signal wiring from the amp while keeping the speakers connected. Does the hiss persist with only the amp in stand alone configuration with speakers attached? If not you might try looking upstream for your hissing culprit, my money is normally on cabling, pre-amp, or ground loop issues.
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post #3 of 18 Old 05-15-2013, 05:45 AM - Thread Starter
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Quote:
Originally Posted by NicksHitachi View Post

To help isolate:

Disconnect all signal wiring from the amp while keeping the speakers connected. Does the hiss persist with only the amp in stand alone configuration with speakers attached? If not you might try looking upstream for your hissing culprit, my money is normally on cabling, pre-amp, or ground loop issues.

Done that and there's some hissing through the speakers but it got louder only when connected. What's the cause?

Does ground loop cause hissing? I thought it causes hum instead. The same cabling, speakers and pre amp has been used in the previous system with no hiss and the only different now is the amp. So what'll be the cause?
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post #4 of 18 Old 05-15-2013, 05:50 AM
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Is the gain structure the same for both amps? What are your trim levels on the pre-amp after installing the new amp? Are they higher?
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post #5 of 18 Old 05-15-2013, 05:55 AM
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Quote:
Originally Posted by Hifi4Hobby View Post

Quote:
Originally Posted by NicksHitachi View Post

To help isolate:

Disconnect all signal wiring from the amp while keeping the speakers connected. Does the hiss persist with only the amp in stand alone configuration with speakers attached? If not you might try looking upstream for your hissing culprit, my money is normally on cabling, pre-amp, or ground loop issues.

Done that and there's some hissing through the speakers but it got louder only when connected. What's the cause?

If ordinary passive speakers hiss when they are disconnected, there is some other acoustic source of hissing in the room. The usual source of hissing noises when the audio system is powered off is the HVAC system.
Quote:
Does ground loop cause hissing?

No.
Quote:
I thought it causes hum instead.

Correct.
Quote:
The same cabling, speakers and pre amp has been used in the previous system with no hiss and the only different now is the amp. So what'll be the cause?

Hooking highly efficient speakers to a very powerful power amp can produce some hissing, particularly if you put your ear right up to the speakers.

I don't have a lot of clarity about your situation as you haven't listed makes and models of the equipment involved.
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post #6 of 18 Old 05-15-2013, 06:02 AM - Thread Starter
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Originally Posted by NicksHitachi View Post

Is the gain structure the same for both amps? What are your trim levels on the pre-amp after installing the new amp? Are they higher?

Gain structure should be the same as i have experienced a full set of line up from NAD M15HD2 and M25 with Paradigm Studio 100 v5 that I can hear hissing from 12 feet away. Cables are the same as previous system which consist of Rotel RSP-1570 and multiple RB-1582..i stick my ears to the speaker and i cant hear any hiss from the Rotel.

For the NADs, I did the Audyssey XT calibration and the gain is in +1, 0 and -1db for each front channels.
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post #7 of 18 Old 05-15-2013, 06:05 AM - Thread Starter
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Originally Posted by arnyk View Post

If ordinary passive speakers hiss when they are disconnected, there is some other acoustic source of hissing in the room. The usual source of hissing noises when the audio system is powered off is the HVAC system.
No.
Correct.
Hooking highly efficient speakers to a very powerful power amp can produce some hissing, particularly if you put your ear right up to the speakers.

I don't have a lot of clarity about your situation as you haven't listed makes and models of the equipment involved.

When the system is off, i dont hear any hiss anymore so it shouldnt be any other device that cause the hissing sound as i counter check with my ears sticking to the speakers to ensure that it doesnt hiss when it's off.

That's what in general feedback and observation where high power amp seems to have some audible noise floor if paired with the high efficient speakers. I think anything from 86db and above will highlight the noise floor of the amp. Anyone can verify if it's the case for some high power and high premium price models such as the McIntosh, Bryston, Classe monoblocks??
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post #8 of 18 Old 05-15-2013, 06:12 AM - Thread Starter
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Maybe the question we should be asking is why does the pre-amp cause the hissing if the rest of the system when unplugged from the pre-amp (or processor) is pretty quiet?
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post #9 of 18 Old 05-15-2013, 06:42 AM
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Originally Posted by Hifi4Hobby View Post

Maybe the question we should be asking is why does the pre-amp cause the hissing if the rest of the system when unplugged from the pre-amp (or processor) is pretty quiet?

My first shot at this situation would be to set all of the gain controls on the back of the M25 to 12 o'clock.

Paradigm Studio 100s are not exceptionally efficient speakers - they are about average.
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post #10 of 18 Old 05-15-2013, 10:03 AM - Thread Starter
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Originally Posted by arnyk View Post

My first shot at this situation would be to set all of the gain controls on the back of the M25 to 12 o'clock.

Paradigm Studio 100s are not exceptionally efficient speakers - they are about average.

Back off the gain means the pre-amp has to work double as hard to get the same output. With full gain, i need to get close to -10db on the pre-amp to get decent home theatre effect on the Paradigms. If back off by half, that probably means my volume has to go over 0db to get similar loudness. I know some power amps sound better when it hits certain power output, but does it applies to the preamp as well?

Yup, i agreed with you Paradigm Studio 100s arent exceptionally efficient and their tweeter isnt as revealing as well. Imagine if you're using the Signature with the beryllium tweeters..what kind of hiss you'll get.
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post #11 of 18 Old 05-15-2013, 02:54 PM
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Originally Posted by Hifi4Hobby View Post

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Originally Posted by arnyk View Post

My first shot at this situation would be to set all of the gain controls on the back of the M25 to 12 o'clock.

Paradigm Studio 100s are not exceptionally efficient speakers - they are about average.

Back off the gain means the pre-amp has to work double as hard to get the same output.

So what?
Quote:
With full gain, i need to get close to -10db on the pre-amp to get decent home theatre effect on the Paradigms. If back off by half, that probably means my volume has to go over 0db to get similar loudness.

Well try halfways up, and if that solves the noise problem, then you can experiment with setting the knobs at 3 o'clock.
Quote:
I know some power amps sound better when it hits certain power output, but does it applies to the preamp as well?

It should apply to neither. Good power amps and preamps sound the same as long as they aren't clipping or mucking around in the noise floor.
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Yup, i agreed with you Paradigm Studio 100s arent exceptionally efficient and their tweeter isnt as revealing as well. Imagine if you're using the Signature with the beryllium tweeters..what kind of hiss you'll get.

Just because a tweeter has better resolution or transient response, doesn't mean that it is brighter.
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post #12 of 18 Old 05-15-2013, 06:27 PM - Thread Starter
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Originally Posted by arnyk View Post

So what?
Well try halfways up, and if that solves the noise problem, then you can experiment with setting the knobs at 3 o'clock.
It should apply to neither. Good power amps and preamps sound the same as long as they aren't clipping or mucking around in the noise floor.
Just because a tweeter has better resolution or transient response, doesn't mean that it is brighter.

Why compromise for what apparently could be a design/quality issue? I swapped the original sets with the subsequent sets that has no hiss issue even at full gain. All cables and accessories remained the same.

Working hard on the pre-amp also means getting closer to its peak output..closer to peak, closer to clip or has higher distortion? smile.gif

The key here is "good"..how many pre and amp out there are really that "good"?

So applying the logic, all seemingly "bright" tweeter probably has good resolution/transient response?
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post #13 of 18 Old 05-15-2013, 09:08 PM
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Have you tried turning OFF Audyssey...
In certain instances this software can create a high frequency boost which amplifies the hiss..



Just my $0.02... 👍😉
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post #14 of 18 Old 05-15-2013, 09:30 PM - Thread Starter
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Originally Posted by M Code View Post

Have you tried turning OFF Audyssey...
In certain instances this software can create a high frequency boost which amplifies the hiss..



Just my $0.02... 👍😉

Ah..that's exactly what i suspected..but upon discussion with my close AV addicts, they've the opinion that even with Audyssey ON, there shouldnt be an audible hiss which the unit by itself is already flawed hence the Audyssey "highlight" the noisy noise floor of the unit. I had this problem with a Pioneer $400 AVR before at this price, there's probably nothing much we can ask for.
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post #15 of 18 Old 05-15-2013, 10:01 PM
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A quality audio system should not hiss...
However, background noise can be amplified for a number of reasons including..
  • Very efficient tweeters
  • Mismatch of components, gain and/or impedances are incorrect
  • Inexpensive components, poor electrical performance specifications
  • Improper setting of the tone controls and/or EQ software with exteme treble boost
  • Poor quality cables

I would concede if one puts their ear up to the tweeter (within 2-3 feet) a small amount of hiss may be audible...
But if the hiss is audible 5' from the loudspeaker or the listening position then definitely something is wrong...


Just my $0.02... 👍😉
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post #16 of 18 Old 05-17-2013, 11:29 AM - Thread Starter
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Quote:
Originally Posted by M Code View Post

A quality audio system should not hiss...
However, background noise can be amplified for a number of reasons including..
  • Very efficient tweeters
  • Mismatch of components, gain and/or impedances are incorrect
  • Inexpensive components, poor electrical performance specifications
  • Improper setting of the tone controls and/or EQ software with exteme treble boost
  • Poor quality cables

I would concede if one puts their ear up to the tweeter (within 2-3 feet) a small amount of hiss may be audible...
But if the hiss is audible 5' from the loudspeaker or the listening position then definitely something is wrong...


Just my $0.02... 👍😉

I think 2 - 3 feet is very very alarming and 5 - 10 feet is definitely plain wrong. If you look at the points you've listed and in my case for example :

[*] Very efficient tweeters - Was using Paradigm Studios 100s and it's certainly not that efficient;
[*] Mismatch of components, gain and/or impedances are incorrect - Same brand and series of pre and power used. If that's mismatched, it's definitely start from the design;
[*] Improper setting of the tone controls and/or EQ software with exteme treble boost - Tone defeated and Audyssey engaged and disengaged. Hiss is there;
[*] Poor quality cables - Audioquest Columbia 72v DBS from pre to power and even subwoofers. Audioquest Rocket 88 SFR for speaker cables big amp'd. My previous system used the same cables and setup but have zero hiss even with my ears stick to the tweeter. The only thing changed subsequently is the pre and power amp.

Many of these hissing gets away by the owners allowing and ignoring it as they felt it's not something they cant live with so it's an expectation matching theory too. Sometimes this has to do with the owner's hearing as well and unfortunately i have a sensitive ears frown.gif

For one i believed that if you're going to pay in thousands for products out there, they should have what it's worth to back it up in technical excellence, design superiority and parts quality. Doesnt it make sense?
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post #17 of 18 Old 05-17-2013, 01:11 PM
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Quote:
Originally Posted by Hifi4Hobby View Post

I think 2 - 3 feet is very very alarming and 5 - 10 feet is definitely plain wrong. If you look at the points you've listed and in my case for example :

[*] Very efficient tweeters - Was using Paradigm Studios 100s and it's certainly not that efficient;
[*] Mismatch of components, gain and/or impedances are incorrect - Same brand and series of pre and power used. If that's mismatched, it's definitely start from the design;
[*] Improper setting of the tone controls and/or EQ software with exteme treble boost - Tone defeated and Audyssey engaged and disengaged. Hiss is there;
[*] Poor quality cables - Audioquest Columbia 72v DBS from pre to power and even subwoofers. Audioquest Rocket 88 SFR for speaker cables big amp'd. My previous system used the same cables and setup but have zero hiss even with my ears stick to the tweeter. The only thing changed subsequently is the pre and power amp.

Many of these hissing gets away by the owners allowing and ignoring it as they felt it's not something they cant live with so it's an expectation matching theory too. Sometimes this has to do with the owner's hearing as well and unfortunately i have a sensitive ears frown.gif

For one i believed that if you're going to pay in thousands for products out there, they should have what it's worth to back it up in technical excellence, design superiority and parts quality. Doesnt it make sense?

We know those NAD components well, and have visited many times their subcontractor factory in Nanjing, China, they are solid, well designed/built products. To eliminate the hiss, you need to do more troubleshooting..

1. If you disconnect the pre-outs > main-Ins, does the amplifier still hiss?
2. What source is connected when the hiss is most audible?
3. Is there any cable box, Sat tuner or PC connected to the preamplifier?
4. Have you ran a direct independent ground between the reamp and amplifier

Over the years, we have installed many, many systems many costing up to $100K and we will not accept an audible hiss. If you have an audible hiss, then I would suggest that you should have each component checked carefully.. Hopefully with a shop that has an AP system, as you may have a defective component with an out-of-spec noise floor... If not, take your preamp and amplifier back to the store and try it with another unit..

Just my $0.02... 👍😉
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post #18 of 18 Old 05-17-2013, 09:25 PM - Thread Starter
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Originally Posted by M Code View Post

We know those NAD components well, and have visited many times their subcontractor factory in Nanjing, China, they are solid, well designed/built products. To eliminate the hiss, you need to do more troubleshooting..

1. If you disconnect the pre-outs > main-Ins, does the amplifier still hiss?
2. What source is connected when the hiss is most audible?
3. Is there any cable box, Sat tuner or PC connected to the preamplifier?
4. Have you ran a direct independent ground between the reamp and amplifier

Over the years, we have installed many, many systems many costing up to $100K and we will not accept an audible hiss. If you have an audible hiss, then I would suggest that you should have each component checked carefully.. Hopefully with a shop that has an AP system, as you may have a defective component with an out-of-spec noise floor... If not, take your preamp and amplifier back to the store and try it with another unit..

Just my $0.02... 👍😉

I agreed with your claim that NAD are well designed and well built "physically" products because it reflects on the actual unit that is solid, has good appeal and even nicely packed. I think many of us are attracted by such factors hence "jump ship" to them. However, why is it that we have audible fan noise on these well designed and built models and for a few of us here at AVS that actually own the M15HD and HD2 have the "Check DSP" problem? My ex system was the Rotel. They also are Made in China but Rotel claimed they "own" the factory themselves whereas NAD seems to "oem" their manufacturing to the "chinese" without "owning" the factory. That can makes the different where sub standard parts are dropped into the production and resulted in end users feedback over the glitches that's concerning, annoying and even very frustrating.

The previous hissing case i have did all the check and the results are as follows :

1. If you disconnect the pre-outs > main-Ins, does the amplifier still hiss? Lower hiss;
2. What source is connected when the hiss is most audible? All components were disconnected from the pre-amp;
3. Is there any cable box, Sat tuner or PC connected to the preamplifier? Nope;
4. Have you ran a direct independent ground between the reamp and amplifier? Yes. I have added additional ground using the ground out from the amp connecting them to different ground but i heard no different in the hiss generated. Frankly i thought different grounding can only solve the humming issue and up until now, i dont have hum problem in any of my system setup (keep my fingers crossed for future ones);

Lenbrook initially want to deploy their technician to my place to check on the hiss but upon i told them to bring a new replacement unit over and swap the one which is confirmed to have excessive hissing that needs attention of replacement/repair of components within, they decided to rather deploy another "factory A stock" over which has a paper tape attached at the bottom with some Chinese wording written on it (too bad i didnt took a photo of it so i have nothing to proof on this) and at that point of time, i have a bad feeling on this replaced unit and unfortunately my guts feeling is right, it has gone completely malfunctioned with the "Check DSP" initially displayed and now, it only make the "buzzing" sound.

The critical point here is if you have good design but the end products cant even live up to the basic specifications, then it's kind of wasting the whole effort. The best manufacturer who stands by its products that dares to admit their products issue, make rectification and provide total customer support and satisfaction will earn the business over long term ultimately.
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