Center channel "farting" at high volume

L

lucassean

Audioholic Intern
Hello,

I have Onix Ref 1 moniters with a Ref 100 center that I just got used. I'm driving them with a few yrs old Pioneer VSX-815 pre outed to a used B & W AV5000. I was using an AV123 ELT 525C before the ref 100. When I cranked the volume to quality listening levels both center channels break up at low base points in the music. It sounds like a farting noise. The AV 5000 has level adjustment knobs in the back. I had the three front channels set to 2:00. I've since back off the center to 12:00 which seemed to help. I'm going to do some isolating procedures with the ref 100 by trying on my main system in the family room. I'm thinking there's something in the amplification though as both speakers reacted the same way. Does anyone have any ideas? Thanks.
 
Seth=L

Seth=L

Audioholic Overlord
The VSX-815 might not actually allow size settings for speakers to be passed through the preouts, I've seen this kind of idiocy before on receivers. It's most likely the "farting" sound you are hearing is tell tale sign of mechanical stress signified by the voice coil hitting the back of the magnet structure (which it's not supposed to ever touch). Prolonged mechanical stress such as this will ruin the voice coils on the mid-bass drivers in the center channel thus ruining the speaker for the most part. I'd recommend attempting to to run the center speaker through the receiver instead of the amplifier with the center speaker set to small and the x-over set to 80Hz on the receiver at the minimum. If the problem still occurs the damage to the speaker was done before you got it, or it's already been damaged from recurring mechanical stress. There is an outside possibility the amplifier you have is clipping in some odd way, but it's unlikely.

The most likely scenario is that the center speakers are receiving a full bandwidth signal when they should receive nothing below 80Hz. Center speakers aren't meant to reproduce bass sounds, so there's no reason to send a signal to a speaker that isn't meant to play it when there are subwoofers designed with the specific purpose of handling low frequencies. The first step you should take is to check and see if the center is even set to small and the cross-over is set to at the least 80Hz. If it already is set to small and the full bandwidth is going to the center speaker regardless of what setting you choose then the receiver's bass management has no affect over the preouts (only God and the people that designed it would know why). Having said that, I don't believe it's likely Pioneer is that stupid. I'm thinking you have the center set to large.
 
adwilk

adwilk

Audioholic Ninja
I just wanted to post in a thread that had "farting" in the title... thanks, OP....
 
S

sptrout

Audioholic
Have you checked the condition of the speakers? I had a similar problem a couple years ago that happened only once in a while with certain frequencies. I even had problems at first trying to figureout which channel the sound was coming from because it was so brief and unpredicable. The final draw came while watching Pearl Harbor, one scene in particular; it happened everytime. At this point it was very obivous that it was the center channel speaker so I removed the cover and found that the two mid-range cones had rotted-out. So, with specific frequencies, the remaining paper in the cones would vibrate and cause the distortion.
 
TLS Guy

TLS Guy

Audioholic Jedi
This post reminds me of the old Flanders and Swann "Song of Reproduction"!

Flanders: This is a song of reproduction.

Both: I had a little gramophone,
I'd wind it round and round.
And with a sharpish needle,
It made a cheerful sound.

And then they amplified it,
It was much louder then.
And used sharpened fibre needles,
To make it soft again.

Today for reproduction,
I'm as eager as can be.
Count me among the faithful fans,
Of high fidelity.

High fidelity,
Hi-Fi's the thing for me.
With an LP disk and an FM set,
And a corner reflex cabinet.

High frequency range,
Complete with auto-change.
Flanders: All the highest notes neither sharp nor flat,
Swann: The ear can't hear as high as that.
Flanders: Still, I ought to please any passing bat,
Swann: With my high fidelity.

Flanders: Who made this circuit up for you, anyway? Bought it in a shop? Oooh, what a horrible shoddy job they fobbed you off with with.
Surprised they let you have it in this room anyway, the acoustics are all wrong. If you raise the ceiling four feet... put the fireplace from that wall to that wall... you'll still only get the stereophonic effect if you sit in the bottom of that cupboard.
I see... I see you've got your negative feedback coupled in with your push-pull-input-output. Take that across through your redded pickup to your tweeter, if you're modding more than eight, you're going to get wow on your top. Try to bring that down through your pre-amp rumble filter to your woofer, what'll you get? Flutter on your bottom!

Both: High fidelity,
Flanders: FFRR for me.
Both: I've an opera here that you shan't escape,
On miles and miles of recording tape.

High decimal gain,
Is easy to obtain.
Flanders: With the tone control at a single touch,
Swann: Bel canto sounds like double Dutch.
Both: But I never did care for music much,
It's the high fidelity!


Flanders: This is perhaps a good moment to explain that we don't normally have these things standing around here, but tonight they are recording this - stereophonically, in fact - for posterity. So wherever you're sitting now, that's where you'll be on the record.
Sit up nice and straight. Any of you feel like rolling in the aisles or being carried out helpless with mirth, this is a jolly good night to do it! Do you want to say hello to posterity?
Swann: Hello!
Flanders: Hello, Posterity! If we sort of move around a bit, they'll use it for demonstration purposes.


These lyrics are from the Drop of a Second Hat, at the dawn of the stereo age.

This song is on my mono album "At the Drop of Hat", well before the stereo age, at the start of the British Hi-Fi craze of the early fifties, when I caught the affliction.

Unfortunately I can't find a free download of the song, you have to pay for it.

As far as the OP is concerned, I doubt it is his speaker but it might be. The drivers on those speakers seem to have an unusually robust motor system. I have been on the French Atohm site. His drivers are Atohm with Scanspeak tweeters.

They may well be a difficult load, and you might need a very robust amp.
 
GirgleMirt

GirgleMirt

Audioholic
Probably port huff. http://www.cnet.com.au/how-does-a-speaker-work-339278272.htm

Bass reflex port

To work around the performance bottleneck of a small speaker cabinet and drivers, a bass reflex port can enhance low-frequency delivery. This is installed either on the front or the rear, and comes in single- or multiple-port configuration.

A catch for such a design -- versus a sealed cabinet -- is the possibility of port noise. This results in a 'huffing'-type sound, but the B&W port shown here is dimpled in order to reduce this effect. Rear ported speakers can tend to complicate installation because they need to be placed at least a metre from the wall in order to supply nimble, tight bass.

Many speakers come supplied with foam bungs to plug the bass reflex port in smaller rooms, and while you lose absolute depth this can cause the bass to become 'tighter'.
If you listen behind the speakers, do you hear the noise coming from inside the speaker? from the port?

If it's port huff, you could simply lower the volume, reduce bass settings, use a sub and use a crossover, etc... But it's normal, every ported speakers will have port huff at one point, it's just one of the speaker's limitations.
 
S

sptrout

Audioholic
He said fart............:D
Bevis.
Actually, it did sound kind of like a fart, but at the time I thought it sounded more like a piece of paper flapping in a strong wind, and only for a couple seconds when it occured, making it difficult to locate.
 
Last edited:
TLS Guy

TLS Guy

Audioholic Jedi
Probably port huff. http://www.cnet.com.au/how-does-a-speaker-work-339278272.htm



If you listen behind the speakers, do you hear the noise coming from inside the speaker? from the port?

If it's port huff, you could simply lower the volume, reduce bass settings, use a sub and use a crossover, etc... But it's normal, every ported speakers will have port huff at one point, it's just one of the speaker's limitations.
You know, that is a good thought. His center is rear ported. However if a speaker is designed correctly it will not have port huff. It is a matter of having a large enough port to get vent air speed velocity at least below 27 m/sec and if possible below 18 m/sec.
 
njedpx3

njedpx3

Audioholic General
You know, that is a good thought. His center is rear ported. However if a speaker is designed correctly it will not have port huff. It is a matter of having a large enough port to get vent air speed velocity at least below 27 m/sec and if possible below 18 m/sec.
As usual TLS --nice info --- I just try to be a sponge ;)
 
Seth=L

Seth=L

Audioholic Overlord
This post reminds me of the old Flanders and Swann "Song of Reproduction"!

Flanders: This is a song of reproduction.

Both: I had a little gramophone,
I'd wind it round and round.
And with a sharpish needle,
It made a cheerful sound.

And then they amplified it,
It was much louder then.
And used sharpened fibre needles,
To make it soft again.

Today for reproduction,
I'm as eager as can be.
Count me among the faithful fans,
Of high fidelity.

High fidelity,
Hi-Fi's the thing for me.
With an LP disk and an FM set,
And a corner reflex cabinet.

High frequency range,
Complete with auto-change.
Flanders: All the highest notes neither sharp nor flat,
Swann: The ear can't hear as high as that.
Flanders: Still, I ought to please any passing bat,
Swann: With my high fidelity.

Flanders: Who made this circuit up for you, anyway? Bought it in a shop? Oooh, what a horrible shoddy job they fobbed you off with with.
Surprised they let you have it in this room anyway, the acoustics are all wrong. If you raise the ceiling four feet... put the fireplace from that wall to that wall... you'll still only get the stereophonic effect if you sit in the bottom of that cupboard.
I see... I see you've got your negative feedback coupled in with your push-pull-input-output. Take that across through your redded pickup to your tweeter, if you're modding more than eight, you're going to get wow on your top. Try to bring that down through your pre-amp rumble filter to your woofer, what'll you get? Flutter on your bottom!

Both: High fidelity,
Flanders: FFRR for me.
Both: I've an opera here that you shan't escape,
On miles and miles of recording tape.

High decimal gain,
Is easy to obtain.
Flanders: With the tone control at a single touch,
Swann: Bel canto sounds like double Dutch.
Both: But I never did care for music much,
It's the high fidelity!


Flanders: This is perhaps a good moment to explain that we don't normally have these things standing around here, but tonight they are recording this - stereophonically, in fact - for posterity. So wherever you're sitting now, that's where you'll be on the record.
Sit up nice and straight. Any of you feel like rolling in the aisles or being carried out helpless with mirth, this is a jolly good night to do it! Do you want to say hello to posterity?
Swann: Hello!
Flanders: Hello, Posterity! If we sort of move around a bit, they'll use it for demonstration purposes.


These lyrics are from the Drop of a Second Hat, at the dawn of the stereo age.

This song is on my mono album "At the Drop of Hat", well before the stereo age, at the start of the British Hi-Fi craze of the early fifties, when I caught the affliction.

Unfortunately I can't find a free download of the song, you have to pay for it.

As far as the OP is concerned, I doubt it is his speaker but it might be. The drivers on those speakers seem to have an unusually robust motor system. I have been on the French Atohm site. His drivers are Atohm with Scanspeak tweeters.

They may well be a difficult load, and you might need a very robust amp.
I've got 3 words for you.

YOU ARE OLD!

:D
 
Seth=L

Seth=L

Audioholic Overlord
I know, but appertaining to the title of the thread I think you left off the last word!
That'd be 5 words old man, one's an article.:D I suppose I could make a contraction, but I believe it's still considered two words.;)
 
L

lucassean

Audioholic Intern
Ok,
:D I'm still smiling at my late night sound description wording. It came from the drivers in the front. I looked at the speaker levels only to find the center at +4.0 db so I backed every speaker down to 0 and cranked it up. I haven't heard it yet. Fingers crossed it's solved. Thanks for the humor and suggestions. :)
 

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