Thought that might grab some attention. I seem to be having a small problem with my m80's.... I think.

When I put my ear up to the tweeters on my m80's I hear a slight hissing noise coming from them. It kind of sounds like an air mattress with a very slight leak (hence the title). I put my spl meter right up to the tweeters and it does not pick up anything... so it is a very slight noise.

at first I thought that the noise was part of the recording... but it shows up as soon as I turn on my receiver.

I have to get pretty close to the speaker before I hear it...

The hissing is still audible with all of my other components turned off and unplugged.

Is this normal?

What is the cause?

Thanks guys!

It's your nice shiny new receiver

Recheck all the wiring just incase there is a loose strand touching something it shouldn't be.

all the wiring looks good to me.

When you put your ear up to your tweeters is it completely silent?

This is normal, some power hiss is normal. I hear it also in my 80's.

No, I get some noise, but it's never really bothered me. It has been a minimal buzz or hum or white noise type thing. I have to put my ear right up to the tweeter to hear it, though. Virtually unnoticeable otherwise.

Phew. so you are telling me I don't need to spend $700 on a not home depot air dried maple wood power strip stand or some traids from shady maple?

Seriously though, is this something a 'power conditioner' would cure? The sound is not audible from my seating area so it is not a big concern... I have to put my ear up to my M80's like they are telling my a secret.

I just wonder if/how it can be eliminated and what the cause is.

thanks,
T

Gremlins.

I have a tripplite power cond/surge HTPOWERBAR10 setup and it does not fix such an issue. Your mileage may vary.

http://www.tripplite.com/products/product.cfm?productID=2812

I asked the same question months ago when people thought I needed an exorcist in my basement as I was having weird things happen. JohnK, and others assured me this is fine. If you can't hear it unless you put your ears up to the speaker grill covers I would not sweat it.

If I crank my Denon up to the MAX, with no music playing, I can barely hear the hiss/buzz from about 10" away.

T, most solid state amplifiers have an extremely low noise level which is inaudible in use, but there's always some. When I turn the receiver volume control to max and put my ear a few inches away(with no program being played, of course), there's a very faint hiss from the tweeter and hum from the midwoofers. This of course isn't normal use and isn't audible at all a few feet away anyway. So, what you've described wouldn't appear to be of any audible significance.

Unless it is a lot worse than what JohnK has just described, it is a frequent thing that I usually refer to as the "space shuttle" syndrome. If lots and lots of top notch engineers cannot make a rocket that can't blow up once in a while, what is the probabily that regular engineers with create something totally perfect?

Understand that this is a joke... I have great respect for the engineers who built/work on the space shuttle.

My 'problem' is no different than described by sirquack and johnk.

glad to know this is normal.

I do however still notice somewhat of a rattle coming from my sub.

I thought I had fixed the issue by tightening the amp plate. It pretty much did resolve the rattle, but on very demanding explosions and such I can hear a rattle. It only happens when I am playing at LOUD volumes (sorry I have not taken an spl reading). It is more apparent when I up the gain on my sub via the denon from -10db to -8db which I often do for movies.

it sounds like the rattle is coming from the back of the sub. Usually when I put pressure on the amp plate it goes away. However, there was one particular time when it sounded like the entire box was going to rattle apart.

I need to decide if this is something to call axiom about or not.

When you say -10dB are you talking about the receiver sub levels, or the main volume? That seems pretty low. Normally, you want to be closer to 0dB and have the volume(gain) on the back of the sub lower. Maybe your running your sub volume to high and creating rattles, not sure.

My old amp, a Kenwood M2a, had this hiss you speak of. My current amp, a Rotel RB 1080, is dead quite.

I told you to put a beaver on your sub. Failing that, use a chunk of granite.

The hiss (junction noise from transistors/FETs) is perfectly normal. Just don't get speakers that have a sensitivity of 120dB/W/m.

sirquack, I have the volume knob on the ep 500 set at about 7 oclock. I used the 3808 audessey auto set up- it set the at -10db in the denon. Verifying with an SPL meter the sub was pretty close 75 db along with all of the speakers.

Mojo, I am not sure that applying weight on the top of the sub fixes the issue. Pressing on the back generally does.

>>I need to decide if this is something to call axiom about or not.

If you're not sure, call Axiom

Have you tried sticking your arm in the port to see if the rattle is coming from the port tube ?

The rattle I initially heard was audible from my couch and it was higher pitched. It occurred at moderate to low volumes. This is gone after tightening the amp plate.

I watched a few clips from an LFE demo dvd that i obtained from AVSforum. Some clips were from the haunted, star wars episode II, and finding nemo.

I checked the output during some of the starwars explosions and peaks were near 100 db from my listening position. The rest of the movie was around 80 db, but peaks at about 97 occasionally. I guess what I am hearing for the most part requires me to walk up to the sub to hear it. A particularly long rumble from the haunted caused the vibration/rattle sound on the back of my subwoofer (this sound was audible within arms reach of the sub at normal listening volumes. If I cranked up the main receiver volume and upped the gain of the sub a little through the denon from -10 to -8db it was auidible from my couch) This rattle/vibration noise will completely stop if I press on the back of the sub or the side of the sub towards the back. I do not have to press on the amp plate directly.

So it seems that if I have to walk up to the sub during a 100db explosion to hear a rattle that is no big deal right? I just don't want to hear anything coming from my sub but LFE... what do you think?

short of sending a completely new ep500 I do not know what axiom could do for me...

Try Mojo's suggestion and put something heavy(10-20lbs) on top of the sub to see if it helps. It does sound like an enclosure vibration. Maybe Axiom needs to beef up their bracing.

LOL!!!!!

Well I called axiom with regards to my sub. Someone will be getting in touch with me tomorrow sometime to help figure this thing out.

I listened to the sub carefully during some DVD scenes and basically cut out the other speakers so I could concentrate on the sub.

There is definitely some internal vibrations or rattling somewhere inside the enclosure that does not sound normal. I can not tell if it is from the driver, the amp, or the box itself.

Hopefully I can get a solution worked out with axiom tomorrow.

I had a rattle with a EP500 I owned at one time. At first I took the driver out (be careful very very heavy) and thought it was the wires bouncing on top of the port. Then I noticed the internal speaker wire terminals were a little loose, so I took some black electrical tape and secured them.

I still had the noise. Then I found if I applied pressure with my fingers to the back amp plate in certain locations, I could get the noise to stop. They sent me a new amp and all was good.

Actually I just got done reading a post of yours about that very issue. I printed off the directions/order that axiom told you to open/check.

JC from axiom told me to open her up and have a look. I took out the amp and took off the plastic boot that covered the amp. All wires appeared to be tight on both the amp and driver. The only wires that were touching anything were the wires that ran inside the plastic boot from the amp to the speaker terminals. I tried to tuck these wires away as much as possible. Nothing looked out of place or broken on the amp, driver, or anywhere else. The white foam stuff was not lined up against the walls of the enclosure well so I tucked them back a bit. I tighted the hex screws on the back side of the port a bit (it was very hard to fit my hand in their though)in case the noise was comming from the port.

Anyway, I got it put back together and the noise is still there.

Axiom will get back in touch with me tomorrow and we will work something out.

hmmm.... is the amp plate on the ep600 the same size and does it have screw holes in the same place as the 500?

IF so I wonder how much convincing/cash it would take to talk axiom into providing me with an ep 600 amp to slap on the back of my ep 500

Try sticking your arm in the port tube -- that's the other place where the occasional rattle has shown up.

Yeah John, but I understand that's how BigJohn got started.

I believe it's the same amp form factor.

Don't put your tongue on the 33,000uF cap terminals.

>>Yeah John, but I understand that's how BigJohn got started.

OMG, I couldn't live with *that* on my conscience.

What harm can a mere 0.33 farads do?

0.033F.

I actually just realized I was off by a factor of 10 and came to correct myself.

dang it, you beat me to it.... suddenly my smart comment is not so smart anymore ;p

Maybe my memory is wrong, but I could swear I've seen 1 F capacitors in the car audio section of Good Guys.

Tell me I'm wrong. That's just scary.

I was debating whether or not I should correct you. But I couldn't let you go through life believing 33,000 uF was 0.33F.

There are lots of 1F capacitors for car audio purposes. The sub amps used in vehicles have rinky dinky power supplies. During a heavy bass hit, the sub can go dead for a few seconds because the power supply can't keep up (and neither can the battery because it has a relatively higher equivalent series resistance). The cap delivers the required energy so as not to starve the amp.

Axiom's subs have beefier power supplies. Any more capacitance and it would likely be a waste. Besides the 33,000 uF, there are other, smaller caps in there too.

T,

The hiss is there with most receivers. All of mine have had that with one exception, my Marantz. My Rotel rig has no hiss either.

The sub rattling may be the driver. I had to replace my 600's a while back. If it is, JC will hook you up.

I always thought the hiss was caused by cosmic background radiation. Shows what I know.

I thought it was caused by Dana Carvey's George Bush impression.

Axiom is sending me a new amp. They think the problem is with the plastic boot that covers the amp. They suspect that it might not be sealing properly.

I will report back when it arrives.
Hopefully this solves my problem!

Any more feedback on this, Ter?