Noise floor on Heritage systems

[Rudy81]

Now that I am getting more comfortable with my system, I am noticing the littlest of things. In this case, my system has an audible hiss from all my speakers. I know SOME noise eminates from all systems and more so on highly efficient horn loaded speakers.

Just curious as to what levels of hiss you guys are experiencing....if any, particularly if you have Khorns, Belles or La Scalas.

Suggestions for reducing the noise are welcome.

This,BTW, is not a ground loop humm.

Thanks.

Rudy81

[marksdad]

sorry dude, no hum here? complete silence, but i used to when i ran rotel gear?

[Rudy81]

It's not a horrid hissing sound, just noticeable in a quiet room. I will have to troubleshoot a little. A guy on the AVS forum with the HALO C2 and Klipsch Heritage is reporting the same low level hiss.

[artto]

Each additional stage of amplification adds noise. The phono preamp sections typically will add the most noise, followed by the high level preamp/control center, and then the power amps. The preamp sections typically have more gain (amplification factor) than the power amps. The power amps will amplify any noise in the signal path that precedes them. The best results are usually achieved when all stages are in what is called unity gain. In other words, each stage of amplification contributes the same proportion of amplification. Be aware that there are no standards to measure or obtain this.

One alternative if you are using separate preamp, power amps, is you can connect the high level sources, such as CD or tuner, directly into the power amp inputs. If your power amps and/or source does not have a volume (gain) control, obviously it will be very difficult to control the volume, especially with speakers like Klipsch.

For what its worth, Ive gotten better noise results from my tube power amps. With the preamp/control center outputs in the mute mode, I can turn the power amps all the way up, put my ear on the Khorn grill cloth, and its dead silent. If I do the same thing with a Crown D150 or DC300A, solid state amp, which technically speaking measure 20dB lower noise according to standard test methods, I can clearly hear the noise anywhere in the room. Go figure. Obviously something is wrong with the test methods/standards.

[Rudy81]

I know all the figures in the audio world don't mean much these days. It has all become a marketing game.

[Q-Man]

With my Yamaha A/V receiver, it's dead silent with

my ear to the tweeter. I added a six channel McIntosh power amp and now my tweeters hiss, but I have to put my ear close to the tweeter to hear it.

[mark1101]

I have had Klipsch speakers for many years and had them connected to many different amps. All solid state. I always had some low level of hiss. Albeit it was really low, but there.

It was not until I got the Scott tube amps that I can now turn it up all the way with a CD on pause, or no input, and get dead silence. I have to say that I can sometimes easily hear hiss in the music between songs which is attributable to lousy source material, but no hiss in my system now.

[Rudy81]

mark1101:

Great, now I'm going to get sucked into the tube amp frenzy!

[hwatkins]

I too run solid state and have for years. They do all hiss that I have experienced, however the better units do not do so in reasonable listening power (that said - even on the better solid state this hiss is clearly different for different inputs). I cannot hear the hiss on my Denon (with no source active) unless the volume control is at unreasonable levels. At reasonable levels, in a very quiet room with my ear within an inch of the horns, concentrating on the ear I can finally discern the hiss. Barely.

Good or bad? Don't know. I'll still have SS in most of my systems..minor issue with me.

[WMcD]

I have been running low power two channel amps from the orient with no noise problems.

I bought and tried a couple of budget HT receivers. In each case, when switched into a mode where there was digital signal processing, the noise level went up. So I returned them and backed away from the project of HT. I conclude the problem is not with the audio section, rather the digital.

In recent times I'm going back to the HT set up. This issue, though, needs a close watch.

Gil

[IndyKlipschFan]

If you have cable/ satelight tv hooked up, do this experiment... Take the cable on the input of the cable box out and see if the hum dissapears... (use any input but TV, on your receiver.) If you do sometimes the cable will introduce a ground problem and make the problem for everything else noise wise.. Also makes thos all white screens hum too.

I bought a simple plastic surge ground loop device from Ovation Audio here in Indy it cost 10 dollars...and solved all my noise problems.. hope this helps.

Mondial here at Klipsh makes a fancier one..

Same principle I believe.

[mark1101]

Rudy,

Yes, you will eventually get sucked into to tube land if you want to get the most out of the Klipsch. Warning. It's powerful suction. So if you want to avoid it, my advice is stay the hell out of the 2 channel forum.

But otherwise, it's the right thing to do. Trust me.

[Rudy81]

Well, that makes me feel much better....

[Marvel]

Rudy,

Have you hooked up the Heresy's you have to the same amp? I have a less expensive Sony receiver (DE525), and I get no hiss from the my Heresy tweeter with it. The way some people here have put down the Sony gear, maybe it just doesn't have any high end.

Marvel

[Rudy81]

Yes, I have hooked up the Heresey's. Same hiss, just lower level of hiss, probably due to the lower efficiency of the speaker.

I know it is not the amps, since I hooked up just the amp and speakers and it is dead quiet. I have to stick my ear next to the tweeter to hear anything at all. It definately is caused by the pre/pro.

I have ruled out the speaker wires and amps and the other gear. The hiss is still present with just the pre/pro, amps and speakers.

[LarryC]

Rudy,

After having dealt with such noise issues with Klipschorns for many years, I feel quite sure you are hearing the noise from the part of the preamp circuitry after the volume control. The fact that it goes way down if the preamp is off (and probably if you use a mute switch) makes that really likely. The next "test" is to see whether the noise rises or falls when you turn the volume control up or down. I'll bet it doesn't, but that it stays constant with volume control position unless you turn it way up. I guess I think that most amps are extremely quiet, though SS is probably a little quieter -- it's almost irrelevant, since the preamp noise overwhelmes it anyway, or so my experience has been.

I suspect the key is that your amplifier is quite "sensitive," as most are, on the order of 0.5 to 1.0 volts in for 100 watts out, or the equivalent. I formerly had an amp that required 0.675 v. in for 25 watts out, which is equivalent (I think) to 1.35 v. in for 100 watts out, and it was reasonably quiet. I can NOT use a 0.5 v/100 w. amp in my system!

The issue of phono stage noise was discussed earlier. As in all pre-volume control stages, the ratio between the signal and noise appears to be constant. In my system, phono stage noise is not an issue IF I have a cartridge with adequate output.

The problem may also supposed to be related to preamp gain -- a recent Stereophile or TAS review compared two preamps, one with over 20 db linestage gain and the other only 15 db or maybe less. They remarked on the relative quietness of the latter in combo with the amp they were using.

So, my guess is that you have a preamp-amp-Klipsch/high efficiency mismatch. While I doubt that tubes vs. SS holds much of a key, one of the great advantage of Scott (and Fisher or EICO) integrated amps is that amp-preamp matching issues are addressed internally, and they apparently are very quiet at the speaker. Besides, tubes really DO sound better!

My $0.02.

[Rudy81]

Larry:

Thank you for your interest and your comments. My system is supposed to be matched. All components are Parasound HALO. As you surmised, the problem is in the pre/pro section. The hiss does go away with mute switch and there is no sound with just the amps hooked up. However, turning the volume know DOES affect the hiss level.

I am currently working with Parasound, who thus far have terrific support, on this issue.

[LarryC]

Rudy,

Very good. Good luck! What is your amp's sensitivity, BTW?

[Rudy81]

Larry:

1V. I beleive. Here are the specs:

http://www.parasound.com/halonew/A52details.asp

[jerohm]

This doesn't apply here, but I still find it pretty interesting. For a time I had the Quartet sitting upside down on top of my Mitsubishi television (the horns closet to the tube). When the TV was turned on, but my amp was NOT powered up (but physically connected), you could distinctly hear noise from the tweeter (and maybe the midrange - can't remember). I assumed it was picking up some kind of TV radiation through the speaker cable. However when the AMP was powered up, the tweeter went (pretty much) silent (actually there IS a very low level hiss from my AMP (RB-985) if you put your hear right next to the tweeter).