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Speaker noises

Hi,

I am a newbie in HiFi and HT, and I just bought some used speakers, pre-amp and amp to build my first HT.

I tested my system for the audio part and wanted to know why there are very obvious noises from the speakers. Anyone can hear this kind of noise even in a room that is not so quite and when you are 5-10 feet away from the speakers.
Currently I only have front speakers (Revel F32), a center speaker (Revel voice) and a sub (JL Audio F112).

Below is my configuration. I am using some cheap cables because that's what I have in my hands right now, and the main goal of my testing was to show that the items work (otherwise I will contact the seller for a solution).

1. Laptop playing CD, connected to Pre-amp (Marantz AV7005) using RCA audio cables (like this cable but a cheaper version: http://www.radioshack.com/product/index.jsp?productId=2290564)
2. RCA audio cable from pre-amp unbalanced audio pre-out to Theta Dreadnaught single ended jack. (FL, FR and center signals are connected).
3. audio cable (Gauge 24 bare wire) from Dreadnaught to FL, FR and center speakers).

When I turn the volume down to 0 in the pre-amp, I can hear very obvious noises from all 3 speakers, and the noises basically remain constant when I turn the volume up in the pre-amp. Since all speakers have the same noise, it doesn't look like speakers' problem.
And I also tried a different pre-amp (a much cheaper one), and still get the same amount of noise, so this basically rules out the pre-amp's problem.

One thing I have to let you know is that I am using 24 gauge speaker cables connecting the Dreadnaught to the speakers. Revel F32's user manual has a table listing the recommended max speaker cable length when connecting to this speaker, the max cable length varies depending on the gauge of the cable. The table listed all the way to gauge 18, so gauge 24 wire is not included in the table.

I can understand speaker cables can affect the sound quality, and eventually I will buy some better wires/cables. Now I just use what I have in my hand for some basic testing. But I am not sure if it is going to cause this much noise. I am new to the HiFi and fancy home theater thing, so I am asking for experts' opinion on this forum.

Thank you very much!
deeperblue
11 responses Add your response
lapierre
547 posts
 
Couple of things to look for:

AC Line. Possible you have a noisey AC line. Checkout your outlet and determine if it's the cheap ole 59ยข with below average connectors. Are there other components NON HiFi on the AC circuit?

Solution: Insert AC Noise Haverester and/or replace cheap outlets. Later install dedicated AC line.

Speakers Cables. Ensure your cables (bare strands) are twisted and not touching outside the terminal posts. And ensure cables are not touching other cables which may not be shielded.

Power Cables.
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jpainter236's avatar
jpainter236
115 posts
 
Unplug the power supply from the computer. Is the problem still there? I have a huge problem when I stream video from my computer to my tv/stereo. When it runs on battery, the system is dead quite. Ground loop. Suggestions above are great. I have a Jensen transformer and it it is a blessing if you have cable tv.
roscoeiii's avatar
roscoeiii
1,155 posts
 
Sounds like a ground loop to me.
swampwalker's avatar
swampwalker
5,138 posts
 
Can you describe the noise better? Is it a hum, a buzz, static, hiss, etc?
xxqq250
43 posts
 
As long as there is nothing defective with your cables, I really doubt they are the problem. Others have mentioned ground noise; I agree, that is definitely a good place to start. Also, are you sure you are running the theta in single ended as opposed to balanced mode? I use Ayre amps. Your Theta is designed by the same person that owns Ayre so there are probably some similarities between our amps. On my V5's, if I don't flip the switch to SE when using non balanced components, I get a hum. (Actually, that's not entirely accurate. If I use a really well shielded cable like Audioquest, I get no hum and can leave it in balanced mode. The only reason I bring this up is that it sounds better like this and may help you out in the future.) The only other thing I can think of is some type of gain mismatch between your components. I have a Wadia CD player and a VAC amp that I had been using for a while with no problems until I got a very efficient pair of speakers (Wilson). This led to a hum and I had to back off the gain on the Wadia. As some of the others have stated, I would first look at the grounding issue. It makes sense, and what ever you do, don't spend any $ until you are sure what the problem is. (And don't sell anything either. Nothing worse than taking your best component and getting rid of it thinking that it is the problem. I know from experience.)
dalecrommie's avatar
dalecrommie
91 posts
 
Hello. I am a newbie also. And I save spent a bunch on this hobby, so I feel I do have something to say at this point.

If you want to think like I used to, then forget cables. Interconnect, speaker and power. My speaking about this on Audiogon, and other. Now how could I say this any better, you have to take a chance. I already know the best. But I am not going to sell you, but do not neglect them.

Of course, the best cables do not come from the king Audioquest, unless you love the big seller. You can get them from them. Now, if you think any seller could, or would sell them in little derivations, then please get real.

I know, and it has been in print other than me.
almarg's avatar
Ag insider logo xs@2x
almarg
9,670 posts
 
First, if you already haven't, try disconnecting and turning off the sub.

Second, looking at the manuals for the various versions of the Dreadnaught, it appears that some modules on some versions have a switch on the rear to select between the balanced and unbalanced inputs, and some don't. It is claimed that the switch is not necessary on the modules that don't have it, but I don't necessarily believe that. If you are using modules that don't have a switch, you may need to connect a jumper between pins 1 and 3 of their XLR input connectors.

To do that, you would need a short piece of solid (not stranded) wire, that is of sufficient gauge to fit snugly, so that the connection is physically secure. Obviously, have the amp turned off while you are inserting the jumper.

Also, the Dreadnaught's manual emphasizes that it is imperative that the AC safety ground connection of its power plug not be defeated, for performance reasons as well as for the usual safety reasons. If by any chance you are plugging it into an ungrounded (2-prong) outlet, using a cheater plug (a 3-prong to 2-prong adapter), that could conceivably be causing or contributing to the problem, particularly if the adapter is not connecting the safety ground pin on the power cord's plug to the wallplate screw.

I don't think that the use of 24 gauge speaker wire, btw, has anything to do with the problem, although as you realize it is certainly non-optimal sonically.

Regards,
-- Al
deeperblue OP
8 posts
 
Thank you for all responses. I will spend time to check everything everyone has suggested. And when things are finally solved, I will post update here.

To be honest, I didn't really know what is a "60Hz hum sound", until I found this on YouTube: http://www.youtube.com/watch?v=SVZ2P0KsLic. Now I know, I think this is the sound I am hearing. I will start with ground loop and see if it is the problem.

Thanks for everyone!
deeperblue OP
8 posts
 
Just some update:

After I switched to balance table, the hum is gone.

Thank you very much for all your help!
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