Author Topic: what the heck...chuffing?  (Read 590 times)

Offline Nick B

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what the heck...chuffing?
« on: February 01, 2021, 12:14:16 AM »
I was playing a cut on a very nicely recorded album streamed via Roon and I heard this horrible noise in the low registers a couple of times. Seemed like it was emanating from the rear port. The only thought I had is maybe this is what chuffing is. I’ve never heard it on my system or anyone else’s, but have only read about it. My amp is 600w a side. Guesses/explanations welcome
Van Alstine SET 120 Control Amp
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Offline _Scotty_

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Re: what the heck...chuffing?
« Reply #1 on: February 01, 2021, 01:34:17 AM »
My speakers are also vented and I have used software to examine the infrasonic spectrum of a number of music files and to my dismay I have found that in many cases there was substantial infrasonic content present which could cause my amplifier to waste power, or depending on the loudspeaker design, have excessive driver excursion which could result in damage or at the least a waste of power needed for the reproduction loud passages of music without clipping.
 My bet is that you have unwanted infrasonic information in the stream or at least musical content below the speaker's low frequency reproduction capability.
 I am not sure whether you could filter out the unwanted low frequency noise at your end or not.
The other possibility is that the amp has a stability problem that is manifesting itself as low frequency oscillation which could produce the same effects. If the same chuffing occurs with shorting plugs placed in the input jacks, then there is a stability problem with the amp.
 I not sure if some kind of problem in the preamp upstream could also cause this or not.
Be well.
Scotty



Offline Nick B

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Re: what the heck...chuffing?
« Reply #2 on: February 01, 2021, 01:42:11 AM »
My speakers are also vented and I have used software to examine the infrasonic spectrum of a number of music files and to my dismay I have found that in many cases there was substantial infrasonic content present which could cause my amplifier to waste power, or depending on the loudspeaker design, have excessive driver excursion which could result in damage or at the least a waste of power needed for the reproduction loud passages of music without clipping.
 My bet is that you have unwanted infrasonic information in the stream or at least musical content below the speaker's low frequency reproduction capability.
 I am not sure whether you could filter out the unwanted low frequency noise at your end or not.
The other possibility is that the amp has a stability problem that is manifesting itself as low frequency oscillation which could produce the same effects. If the same chuffing occurs with shorting plugs placed in the input jacks, then there is a stability problem with the amp.
 I not sure if some kind of problem in the preamp upstream could also cause this or not.
Be well.
Scotty

It was quite a concerning sound...happened a couple of times. I would think the amp is stable. Sometimes I’ll admit to playing the system at pretty high levels, which does cause concern on some dynamic cuts. Also the ports are angled and within 18” or so off the wall. I might play that cut again tomorrow. I’m curious how your house and acoustic room are coming together.
« Last Edit: February 01, 2021, 10:56:54 AM by Nick B »
Van Alstine SET 120 Control Amp
Audio Hungary APR 204 preamp
Fritz Carrera 7 BE speakers
Border Patrol SEi dac
Auralic Aries Mini & Mojo Audio lps
Audio Envy cables
Roon, Tidal, Qobuz
PI Audio UberBUSS

Offline _Scotty_

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Re: what the heck...chuffing?
« Reply #3 on: February 01, 2021, 01:54:25 AM »
Still unpacking basement, it had to wait until the the the rest of the house was livable. I am busy putting together shelving for my wife's room. I have just barely started unpacking the book boxes in the listening room.
To quote Roger Murtaugh, I am getting too old for this shit.
Scotty

Offline Nick B

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Re: what the heck...chuffing?
« Reply #4 on: February 01, 2021, 02:17:44 AM »
Still unpacking basement, it had to wait until the the the rest of the house was livable. I am busy putting together shelving for my wife's room. I have just barely started unpacking the book boxes in the listening room.
To quote Roger Murtaugh, I am getting too old for this shit.
Scotty

Roger’s right on that....no need for hard work right now. I’m staying put for a while.  Well, you’re gaining on it. Good luck with all that.

 Nick
Van Alstine SET 120 Control Amp
Audio Hungary APR 204 preamp
Fritz Carrera 7 BE speakers
Border Patrol SEi dac
Auralic Aries Mini & Mojo Audio lps
Audio Envy cables
Roon, Tidal, Qobuz
PI Audio UberBUSS

Offline HAL

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Re: what the heck...chuffing?
« Reply #5 on: February 01, 2021, 03:44:55 AM »
A friends B&W 801 Matrix speaker have port chuff when playing pipe organs with fundamentals in the 17Hz range where the port it tuned.  It was very distinct as the speakers are front ported. 

One method some folks have discussed to break it up is to use multiple straws filling the port.  This lets airflow, but breaks up the turbulent flow. 


Offline BobM

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Re: what the heck...chuffing?
« Reply #6 on: February 01, 2021, 05:25:12 AM »
I've heard it on front ported speakers when playing very low bass information, but it's less noticeable on rear ported ones. If you heard it there... well that's something. You could try stuffing the ports with open cell foam or something that doesn't interfere too much with airflow, but that's going to affect our overall sound and a bit of overkill if it's only on one or two recordings.

Then there's always the upgrade path. (your friends here will always help you spend your money)
Laugh and the world laughs with you. Cry and you'll have to blow your nose.

Offline rollo

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Re: what the heck...chuffing?
« Reply #7 on: February 01, 2021, 12:13:12 PM »
   IMHO. Too much bass energy at high volume. Fritz speakers not known for that at all.

charles
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Offline Nick B

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Re: what the heck...chuffing?
« Reply #8 on: February 01, 2021, 12:36:51 PM »
This was the only time...in any of my systems over the years...that I’ve experienced it. I’ll keep things simple and not do anything  :thumb: I’m not tempted right now to change from my Fritzies.
Van Alstine SET 120 Control Amp
Audio Hungary APR 204 preamp
Fritz Carrera 7 BE speakers
Border Patrol SEi dac
Auralic Aries Mini & Mojo Audio lps
Audio Envy cables
Roon, Tidal, Qobuz
PI Audio UberBUSS

Offline _Scotty_

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Re: what the heck...chuffing?
« Reply #9 on: February 01, 2021, 02:08:15 PM »
There are specific parameters for port sizes that must used when designing a vented speaker system.
If the port size is too small in area, the air velocity in the port will cause audible noises.
 It could be that the speaker design is right on the edge of what is possible in that size of enclosure.
Scotty

Offline rollo

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Re: what the heck...chuffing?
« Reply #10 on: February 02, 2021, 08:21:54 AM »
There are specific parameters for port sizes that must used when designing a vented speaker system.
If the port size is too small in area, the air velocity in the port will cause audible noises.
 It could be that the speaker design is right on the edge of what is possible in that size of enclosure.
Scotty


   Nope. Very well designed. First time I have heard that from a Fritz owner and Yes I sell them. Hals suggestion of straws works very well if ya want to experiment.

charles
contact me  at rollo14@verizon.net or visit us on Facebook
Lamm Industries - Aqua Acoustic, Formula & La Scala DAC- INNUOS  - Rethm - Kuzma - QLN - Audio Hungary Qualiton - Fritz speakers -Gigawatt -Vinnie Rossi,TWL, Mad Scientist, Swiss Cables

Offline _Scotty_

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Re: what the heck...chuffing?
« Reply #11 on: February 02, 2021, 10:26:33 AM »
You misunderstand me. Any vented loudspeaker system has low frequency response limitations. There are going to be limits on both driver excursion and the input power that the driver can handle before damage occurs.
 I have little doubt that the Fritz speaker is well designed, but infrasonic information or the attempt to reproduce low frequency musical content at high SPLs that has fundamentals below the port tuning frequency will catch any vented speaker design out and reveal its design limits.
 That this is the first time that Nick has run into chuffing with 600 watts on tap speaks well for the soundness of the Fritz's design.
Scotty

Offline Nick B

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Re: what the heck...chuffing?
« Reply #12 on: February 02, 2021, 02:56:04 PM »
You misunderstand me. Any vented loudspeaker system has low frequency response limitations. There are going to be limits on both driver excursion and the input power that the driver can handle before damage occurs.
 I have little doubt that the Fritz speaker is well designed, but infrasonic information or the attempt to reproduce low frequency musical content at high SPLs that has fundamentals below the port tuning frequency will catch any vented speaker design out and reveal its design limits.
 That this is the first time that Nick has run into chuffing with 600 watts on tap speaks well for the soundness of the Fritz's design.
Scotty

Thanks for elaborating on this interesting phenomenon, Scotty. In an audio sense, I think of this event now as “a perfect storm”. As I constantly discover new material in Roon, I can’t even recall what CD and song this was from. But I did save it and I’m sure will run across it again. What is puzzling also is this particular recording didn’t appear to have extremely low bass content.
Van Alstine SET 120 Control Amp
Audio Hungary APR 204 preamp
Fritz Carrera 7 BE speakers
Border Patrol SEi dac
Auralic Aries Mini & Mojo Audio lps
Audio Envy cables
Roon, Tidal, Qobuz
PI Audio UberBUSS

Offline _Scotty_

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Re: what the heck...chuffing?
« Reply #13 on: February 03, 2021, 03:41:00 AM »
It is probably just infrasonic noise so to speak riding along with the music like an unwanted parasite.
I've seen this same sort of thing on a lot of music files ripped from CDs.
I have no clue as to why it's there but it certainly can be a problem.
Scotty

Offline HAL

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Re: what the heck...chuffing?
« Reply #14 on: February 03, 2021, 04:47:02 AM »
Just as a note, some of the early RCA Living Stereo recordings have subway noise at very low frequencies in the recordings.  First time I could reproduce it at realistic levels, it was very interesting to hear it.   Been to long to remember which ones.