La Scala's humming

[stevencap]

After sitting in my garage for 4 years I finally hooked up my La Scala's. I had been listening to my stereo through small speakers and I finally got around to switching out the small speakers for the La Scala's. The problem is there is a humming noise coming through the Klipsch's that was not there with the other speakers. I changed nothing except the speakers, so why the humming? Any help would be appreciated.

Thanks,

Steve

[JohnA]

Can they carry a tune?

The humming is from the amp. Their efficiency makes it audible.

[lynnm]

This issue has arisen before and users frequently find the answer difficult to believe but here we go !

Unpowered ie. unamplified speakers do not and cannot hum,hiss,buzz etc. whether they are made by Klipsch or another manufacturer.

The difference you noticed is simply that the Lascallas are far more efficient than the speakers that you had been using and amplifier noise that was too low in level to produce an audible output from your previous speakers is sufficient to be produce an audible output from the lascallas.

You will need therefore to do one of the following:

1.) Find some way to reduce the hum from your amp to an acceptable level or failing that:

2.) Purchase an amp with lower hum which implies being able to test it with the Lascallas. Or failing that:

3.) Learn to live with the hum.

The efficiency that makes the Klipsch line so dynamic and detailed is a mixed blessing for the reasons detailed above. The upside is that Klipsch speakers matched with the right equipment provide breathtaking sound.

If you find the need to go with a new amp consider a low to medium powered tube amplifier. Take a look for a post in the Two Channel Forum by Tom Brennan. He is offering a nice little Antique Sound Lab http://www.divertech.com/mgsi15dt.html tube amplifier at 1/2 of retail. I have heard the MG15 and it is a sweet natured match for Klipsch speakers and offers the versatility of triode (SET) operation or Pentode Push-Pull operation. I own its big brother the AQ1003DT which is a push-pull integrated using EL34's. As much as I love my AQ1003DT I might well have opted for the MG had I been able to listen to them in a side by side comparison. For details on that some other interesting options visit:

http://www.divertech.com/antiquesl.html

Edit:

The MG offers a choice of Triode or Pentode (Tetrode actually) operation and is not push-pull at either setting. Sorry if my brain fart misled anyone .

[WMcD]

I agree with what my fellow poster say, for the most part. One certain issue is that the efficent speakers will show up problems with any amp. They also show up problems with the system as a whole. I suspect the latter is your problem, just from reading.

The usual problem with amplifers are noise or distrortion at low levels. Not typically hum. We have a lot of discussion about the merits of tubes and transistors, and one brand versus another. However, Hum is not a leading complaint when the system is working well.

As you might know, this is 60 Hz or 120 Hz from the power line. It may be that the amp's power supply is not well designed (rare). But more typically, this is getting into the feed circuity by a loose connection or a bad ground.

In my experience, hum, in a system is caused by something flakey with the connections, rather than the amp. So don't go off chasing a better amp if there is another source of the problem.

So do first make sure every connection is plugged in tightly.

Do some investigation. Do all sources, e.g. CD, FM, have the same hum. If one or the other does not, there is something to look at.

So, tell us some more about your amp. If it is an old unit, perhaps there is a problem with power supply regulation. A blind guess is that there is a loose ground connection.

Gil

[lynnm]

Further to William's question. How loud is the hum on a scale of 1 -10 ?

1. Barely audible at high volume with no signal.

2.

3.

4.

5. Clearly audible during quiet passages in music.

6.

7.

8.

9.

10.Very loud at all times.

Make/model/age of amp would be helpful to know. Is it a tube type or a solid state unit?

If the hum persists after you have reseated all of the connections as suggested above try reconnecting your small speakers. If the hum disappears then this clearly is related to the high efficiency of the Lascalla's and you will need to improve or replace the amp.

[Colin]

It probably is the increased sensitivity of the big old horns, which you are not used to. My first reaction to hum however, is to swear softly under my breath - then get up off the couch. Next, I try switching the amplifiers, or other component, from the wall power outlet that it is currently using (pun intended) to another wall outlet. This often works, especially if I run an extension cord to the other wall. I also try a cheater adapter plug, which converts a three prong grounded electrical power plug to a two blade plug. This also works, if you find the appliance making the hum.

[Guest BobG]

It is also possible that the hum is due to the placement of the amp near some other device that is radiating the noise. Try moving the amp, and any interconnect cables (RCAs) to determine if this is the case. Sometimes just a few inches can make a big difference. Also, you may have other electronics plugged in that radiate hum/noise. Check this as well.

[stevencap]

Here is some more info that most of you requested. The amplifier is an NAD 2400. It is about 12 years old. It is solid state. 100 watts per channel. The humming is there all the time. It does not matter what component is ready to play cd, tape, etc. The humming does not get louder when the volume is turned up. All of my connections are good. I can live with the hum as long as I know it is not going to cause any damage to the speakers or any other components. This does not mean I do not want to get rid of it. It is annoying. Thanks

[WMcD]

I think Colin is on the right track.

Again, in my experience, most solid state amps have a noise floor, and not a power supply hum. The hum is probably because of something oddball with the line connection.

Gil

[stevencap]

Could it be that my RCA wires are not of high quality?

[lynnm]

That NAD 2400 looks to be a reasonably decent piece better suited to low efficiency speakers rather than to your Lascalas but you could have a lot worse. As has been suggested above probably the best approach would be to look at your interconnects and wiring as potential noise sources.

The fact that the hum doesn't change with volume setting it is likely that the hum is not coming from your sources, (Turntable,tuner,CD,Preamplifier, etc.).

That leaves a relatively small number of possibilities: For a tech like me that is a good thing !

Diagnostic steps I suggest:

1. Having ensured that all connections between the 2400 and Lascalas are clean and tight isolate the 2400 and the Lascalas from the rest of the system totally by disconnecting everything from the 2400 and the power outlet it is plugged into. If the problem resolves the problem is not with the 2400 itself.

If the problem persists go to 1a.

1a. Use a 2 prong cheater to connect your 2400 to the mains. If the problem persists then the problem is with the 2400 and you must then decide to live with the hum or not.

2.) If the problem is absent with everything disconnected from the 2400 then add the preamp back in and use the steps suggested in step 1.

3.) Continue this process component by component.

Hope it works for you

[Ray Garrison]

Do you have a cable TV system or satellite dish hooked up so you can play the audio through your system? This frequently causes hummmmmmmm problems (even if the equipment is turned off and the input is not selected.) If so, try disconnecting the cable input and see what happens.

If not, do you have any of those inexpensive halogen lamps with the dimmer switch on them? Try unplugging the lamp from the wall if you do.

Just a couple of thoughts...

[HDBRbuilder]

There is one possibility that has NOT been covered here...but this possibility depends on the answers to a few questions, first:

1. Do you hear any hum when OTHER speakers are hooked up to your amp? If the answer is yes, then it is your amp or some other source(or maybe cables or such)...if the answer is no...go to next question.

2. How well did you store your LaScalas? IE., were they completely covered up tightly where nothing could get inside of them while they were stored in your garage? If the answer is no, then do the following:

This is dependent upon the POSSIBLIITY that some critters have done something while they were stored in garage...such as dirt daubers making mud stuff inside em...or maybe paper wasps chewing up some of the paper on the woofers(if they have chewed through the voice coil dust covers, then you may have rubbing voice coils from dust entering there)....sometimes humming can be caused by the workings of critters in your bass bins!

So...how do you ensure this is NOT the case? Well...you flip the LaScalas upside down, take off the bottom panel(the door to the doghouse), remove the woofer, and inspect the face of it to ensure it is in good shape(no paper missing etc)...also give the woofer cone face a good dusting while it is out...then you reach through the motorboard slot and feel for any dirt dauber mud nests and such...removing any you find, and cleaning out anything you find in that part of the soundpathway...also reach into each side of the bassbin to the rear of the bin and feel there...if everything is clear and unobstructed, then clean it up a bit and reassemble everything...then look at your sources to the speakers for the problem! Pretty simple! As a matter of fact, it is a good idea to periodically clean out this area of dust bunnies, cobwebs, and such anyway...even if speakers are inside the house!

NOTE....WARNING...there MAY be some critters nesting there that are DANGEROUS...such as Black Widow spiders...so keep this in mind when you blindly reach into these areas to clear them of possible debris!!