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"Official" Audyssey thread (FAQ in post #51779) - Page 1973

post #59161 of 70896
Quote:
Originally Posted by Theresa View Post

I think Feri's comments about clipping would be correct if limited to subwoofers. The higher order distortion would not be fed to the non-sub drivers, band limited so to speak, and would therefore probably do no harm. The sub could fail if fed too loud a signal, especially if its below the tuned frequency of the sub or if it overheats from a signal too loud for too long a time.

 

Feri seems to be saying that clipping is never a problem and can never cause any damage to ANY speakers. At least that is how I read this:

 

"Keith my friend, clipping of a sinusoidal signal means it's being transformed into a square wave. Feed this into a speaker and the speaker will play it. It will sound distorted, but the speaker does not care, it just plays what is fed into it. Feed a speaker with a distorted signal or a pure signal makes no difference for the speaker. You can't distroy a speaker with a clipped signal because the peak-to-peak voltage does not change. A speaker can only be destroyed by mechanical or thermal overload. A clipped signal will cause neither of these two cases."

 

FWIW, I believe he is entirely wrong that a clipped signal cannot cause thermal overload in the voice coil and thus destroy it. At his behest, I googled the subject and the first page of hits confirmed my viewpoint. (My bolding)

post #59162 of 70896
Yes, feeding a sub too much power for too long will result in failure because of exceeding thermal limits. Many speakers fail because of this. Didn't mean to cast doubt as to the reason for your subs failure. I've read many accounts here of people having parties or just listening at unreasonable levels and having their speakers release "magic smoke" and then not working. Amplifiers too can overheat and fail.
post #59163 of 70896
Quote:
Originally Posted by Theresa View Post

Yes, feeding a sub too much power for too long will result in failure because of exceeding thermal limits. Many speakers fail because of this. Didn't mean to cast doubt as to the reason for your subs failure. I've read many accounts here of people having parties or just listening at unreasonable levels and having their speakers release "magic smoke" and then not working. Amplifiers too can overheat and fail.

 

Oh yes - I have been that man too :)  All in my naive past of course ;)

post #59164 of 70896
I too have had it happen. Back in my teenage days I had friends "crank my stereo up" and blew a tweeter and had a receiver release smoke and fail. It was a nice Fisher tube receiver.
post #59165 of 70896
Keith, after reading your technical note in the FAQ I can now clearly see where your confusion is coming from:

"There is another important reason why it is advisable to avoid maxing-out your sub trim, especially in the positive (+) range. In pro and consumer equipment, different components and manufacturers have different acceptable ranges for the signal inputs and outputs. Exceed this range and you will produce clipped signals in the chain."

This is true. The Pro industry (musicians, recording studios, etc.) uses different signal levels for line out/ line in than the Consumer electronincs industry (Home theaters).

Pro: +4 dBu
Cons: -10 dBu

This means the whole Pro industry is using +4 dBu, while the whole consumer industry is using -10 dBu. Line levels for both industries are standardized, makers can not just do as they want, they have to keep up with these standardized levels. I can't imagine what would happen in either of these industries if line levels were all over the map.biggrin.gif

In the linked article Wayne is talking about matching the gain structures when the same system contains a Pro/Consumer mix.

Now, tell me please, in your household how many Pro gears do you have? I bet none!tongue.gif

Good read here: Line level
Edited by mogorf - 1/19/13 at 7:22am
post #59166 of 70896
Quote:
Originally Posted by djoberg View Post

Quote:
Originally Posted by kbarnes701 View Post

Yes, Feri and I disagree on this. But I am the one who ran his AVR at +10dB and destroyed a sub because of it. Following Feri's line of thinking +10dB ought to be fine, but I know from experience it isn't. I can only tell you what I believe to be true - the sub trim should ideally be well clear of the maximum 'end stops'.

I hear you Keith and believe me, I'm concerned. But do you think it will make a difference (concerning the *clipping* issue) that I turned the trim level down to +3.5dB (and the gain is now at 12 o'clock)?

I've got company coming in a half hour for overnight, so after they leave tomorrow I hope to reconnect my Pioneer and do a calibration to see if the sub is the culprit. If it isn't, then I'll try Feri's suggestion of doing a reset on the Onkyo and the sub. This is all frustrating, because I really do love the sound of the Onkyo and of course I've spent a good 4-5 hours becoming acquainted with it and going through all the various settings.

If the Pioneer still works well (assuming similar microphone positioning for both calibration systems) and if the reset on the Onkyo doesn't help, I would return it. A question for someone who can't return is whether a compromise position of 7/8 on the sub and +5 on the AVR would be safer, in that the sub gain is not maxed out.
post #59167 of 70896
Quote:
Originally Posted by mogorf View Post

Keith, after reading your technical note in the FAQ I can now clearly see where your confusion is coming from:

"There is another important reason why it is advisable to avoid maxing-out your sub trim, especially in the positive (+) range. In pro and consumer equipment, different components and manufacturers have different acceptable ranges for the signal inputs and outputs. Exceed this range and you will produce clipped signals in the chain."

This is true. The Pro industry (musicians, recording studios, etc.) uses different signal levels for line out/ line in than the Consumer electronincs industry (Home theaters).

Pro: +4 dBu
Cons: -10 dBu

This means the whole Pro industry is using +4 dBu, while the whole consumer industry is using -10 dBu. Line levels for both industries are standardized, makers can not just do as they want, they have to keep up with these standardized levels. I can't imagine what would happen in either of these industries if line levels were all over the map.biggrin.gif

In the linked article Wayne is talking about matching the gain structures when the same system contains a Pro/Consumer mix.

Now, tell me please, in your household how many Pro gears do you have? I bet none!tongue.gif

Good read here: Line level

 

That's all red herring Feri IMO. The Pro gear example Max used was just that - an example, to illustrate his point.

 

I do have some Pro gear as it happens - a Crown amp. But that is just as irrelevant. As I said several posts back - we will have to agree to disagree, so please leave it at that. I think you are wrong. You think I am wrong. Nothing you can say will get me to alter the FAQ from its current recommendation of trim levels around +/- 3.5dB because that is the safest option.

post #59168 of 70896
Quote:
Originally Posted by kbarnes701 View Post

That's all red herring Feri IMO. The Pro gear example Max used was just that - an example, to illustrate his point.

I do have some Pro gear as it happens - a Crown amp. But that is just as irrelevant. As I said several posts back - we will have to agree to disagree, so please leave it at that. I think you are wrong. You think I am wrong. Nothing you can say will get me to alter the FAQ from its current recommendation of trim levels around +/- 3.5dB because that is the safest option.

Then, that part of the FAQ is pretty much useless, because it contains information based on (your) false premise. I will repeat for the attention of any and all members:

Any trim set by Audyssey will be safe and will not carry any risk of damage to your subwoofers. The trim value is set by Audyssey to ensure that your subwoofer will play reference level of 85 dB at the MLP.

Anything other you read in the FAQ is red hering.
post #59169 of 70896
Also not sure where are pulling this 85db from that you keep repeating. I assume that's from the 75db with a 30dbfs tone plus a 10db boost for the LFE channel. But I don't know why you keep repeating that number as gospel. During calibration the sub channel is trimmed to 75db at 30dbfs just like the other channels, not 85db. If you send a pure LFE signal at 30dbfs then it will play it at 85db.

But if you play actual content, it will play all sorts of levels. Where do you get that it will "play reference level of 85db"?
post #59170 of 70896
Technical discussion aside, there is a real operational benefit to not running the sub(s) too close to the Audyssey min/max trim values.

I frequently boost or cut the sub trims depending on the content and house occupancy. Having the Audyssey set trims closer to "neutral" leaves the most flexibility.

I'm a little behind on the thread, so if this was mentioned before, sorry for the repeat.
post #59171 of 70896
Quote:
Originally Posted by batpig View Post

Also not sure where are pulling this 85db from that you keep repeating. I assume that's from the 75db with a 30dbfs tone plus a 10db boost for the LFE channel. But I don't know why you keep repeating that number as gospel. During calibration the sub channel is trimmed to 75db at 30dbfs just like the other channels, not 85db. If you send a pure LFE signal at 30dbfs then it will play it at 85db.

But if you play actual content, it will play all sorts of levels. Where do you get that it will "play reference level of 85db"?

bp,

In case the Audyssey chirps go through the "real" LFE channel including the built-in +10 dB boost, then the Audyssey mic should record 85 dB SPL with a -30 dB test signal. If not, then it's 75 dB SPL and I stand corrected. wink.gif
post #59172 of 70896
Feri, because of the normalization feature of Audyssey we have had reports of subs being overdriven. Overdriving *can* cause damage.

And it is not pro gear per se that uses +4dBU, it is balanced lines. Plus any pro gear with single-ended IO will be at the -10.

Jeff
post #59173 of 70896
Quote:
Originally Posted by pepar View Post

Feri, because of the normalization feature of Audyssey we have had reports of subs being overdriven. Overdriving *can* cause damage.

Thanks Jeff. Although I don't really see how this dreaded normalization feature can be related to subwoofer trim settings. Gain knob low -> trim high. Gain knob high -> trim low. In any case the subwoofer (and especially the driver) will receive the same level.
Quote:
And it is not pro gear per se that uses +4dBU, it is balanced lines. Plus any pro gear with single-ended IO will be at the -10.

Of course, you are right about the balanced/unbalanced case. But let's explain why the Pro industry is using balanced and the Consumer industry the unbalaned. Balanced is usually less sensitive to interference especially when it comes to long cable lenghts. Imagine the lenght of cabling at a concert site, not just on the stage but also used to connect the sound engineers who are usually sitting in the middle of the audience in a big stadium.

At home we have much shorter cable lenghts, so there is no real benefit of using balanced. Although there are gear that use XLR cables, ...well...just to give it a cool Pro look, eh? cool.gif
post #59174 of 70896
Quote:
Originally Posted by bfreedma View Post

Technical discussion aside, there is a real operational benefit to not running the sub(s) too close to the Audyssey min/max trim values.

I frequently boost or cut the sub trims depending on the content and house occupancy. Having the Audyssey set trims closer to "neutral" leaves the most flexibility.

I'm a little behind on the thread, so if this was mentioned before, sorry for the repeat.

Yes, this is the most often cited reason. Personally, I think the +/- 3.5db think seems a bit arbitrary in its specificity. All of these arguments we are working through are generalized, so I don't see why it's +/- 3.5 as opposed to, say, +/-5 or 6. My sub comes in at -5 typically with the gain knob at 1/2 way, and it doesn't bother me since the auto on triggers just fine. I actually have it lowered 3db from there (all the way to -8) because my domestic tranquility is improved wink.gif
post #59175 of 70896
Quote:
Originally Posted by mogorf View Post

Thanks Jeff. Although I don't really see how this dreaded normalization feature can be related to subwoofer trim settings. Gain knob low -> trim high. Gain knob high -> trim low. In any case the subwoofer (and especially the driver) will receive the same level.
Of course, you are right about the balanced/unbalanced case. But let's explain why the Pro industry is using balanced and the Consumer industry the unbalaned. Balanced is usually less sensitive to interference especially when it comes to long cable lenghts. Imagine the lenght of cabling at a concert site, not just on the stage but also used to connect the sound engineers who are usually sitting in the middle of the audience in a big stadium.

At home we have much shorter cable lenghts, so there is no real benefit of using balanced. Although there are gear that use XLR cables, ...well...just to give it a cool Pro look, eh? cool.gif

From my "head end" in the rear of my theater to the power amp behind the false/screenwall, by the time service loops are included, it is 50 feet. I have an 8-channel snake for that run.

Jeff

Sorry if I am out of step here, it's difficult keeping up on an iPhone.
post #59176 of 70896
Quote:
Originally Posted by pepar View Post

From my "head end" in the rear of my theater to the power amp behind the false/screenwall, by the time service loops are included, it is 50 feet. I have an 8-channel snake for that run.

Balanced or unbalanced?
post #59177 of 70896
Oops, ... Balanced. That's way to long for single-ended.
post #59178 of 70896
Quote:
Originally Posted by mogorf View Post

Quote:
Originally Posted by kbarnes701 View Post

That's all red herring Feri IMO. The Pro gear example Max used was just that - an example, to illustrate his point.

I do have some Pro gear as it happens - a Crown amp. But that is just as irrelevant. As I said several posts back - we will have to agree to disagree, so please leave it at that. I think you are wrong. You think I am wrong. Nothing you can say will get me to alter the FAQ from its current recommendation of trim levels around +/- 3.5dB because that is the safest option.

Then, that part of the FAQ is pretty much useless, because it contains information based on (your) false premise. I will repeat for the attention of any and all members:

Any trim set by Audyssey will be safe and will not carry any risk of damage to your subwoofers. 

Anything other you read in the FAQ is red hering.

 

The sound output level of 85dB (75dB in fact) has nothing at all to do with it. You don't undersand the point of the discussion, Feri. Batpig has already pointed this out to you and he is right. Max has already explained how the output of one component can be too great for the input of another. 

 

The trim suggestions have been in the FAQ since the FAQ was started, with no objection from you until now. Your position makes no sense - you say that ANY trim level is OK but NOT the trim levels between -3.5dB and +3.5dB. rolleyes.gif

 

 

 

Quote:
The trim value is set by Audyssey to ensure that your subwoofer will play reference level of 85 dB at the MLP.

 

That's wrong too while I'm on the subject. The reference level of the subwoofer is set by a combination of the trim level of the AVR and the gain level of the subwoofer. 

 

That's the bit you are missing.

post #59179 of 70896
Quote:
Originally Posted by batpig View Post

Yes, this is the most often cited reason. Personally, I think the +/- 3.5db think seems a bit arbitrary in its specificity. All of these arguments we are working through are generalized, so I don't see why it's +/- 3.5 as opposed to, say, +/-5 or 6. My sub comes in at -5 typically with the gain knob at 1/2 way, and it doesn't bother me since the auto on triggers just fine. I actually have it lowered 3db from there (all the way to -8) because my domestic tranquility is improved wink.gif

I searched 'Ask Audyssey' and this is what Chris had to say;

"There is no need to worry about getting the speakers to have 0 dB level adjustment. The whole point of calibrating is to let Audyssey measure and automatically set the levels. As long as the sub level is not out of the range that the AVR can handle (–12 dB for most AVRs) then you are fine. This "need" to get the sub close to 0 dB is one of those silly internet myths that have no basis (imagine that!)."

June 26, 2012 04:19 pm

https://audyssey.zendesk.com/entries/74454-bass-management-and-lfe-not-the-same-thing
post #59180 of 70896
Quote:
Originally Posted by bfreedma View Post

Technical discussion aside, there is a real operational benefit to not running the sub(s) too close to the Audyssey min/max trim values.

I frequently boost or cut the sub trims depending on the content and house occupancy. Having the Audyssey set trims closer to "neutral" leaves the most flexibility.

I'm a little behind on the thread, so if this was mentioned before, sorry for the repeat.

 

It's a good point and it is also mentioned in the FAQ as a reason to aim for a trim towards the centre values. Feri is on one of his crusades again :)

post #59181 of 70896
Quote:
Originally Posted by batpig View Post

Quote:
Originally Posted by bfreedma View Post

Technical discussion aside, there is a real operational benefit to not running the sub(s) too close to the Audyssey min/max trim values.

I frequently boost or cut the sub trims depending on the content and house occupancy. Having the Audyssey set trims closer to "neutral" leaves the most flexibility.

I'm a little behind on the thread, so if this was mentioned before, sorry for the repeat.

Yes, this is the most often cited reason. Personally, I think the +/- 3.5db think seems a bit arbitrary in its specificity. All of these arguments we are working through are generalized, so I don't see why it's +/- 3.5 as opposed to, say, +/-5 or 6. My sub comes in at -5 typically with the gain knob at 1/2 way, and it doesn't bother me since the auto on triggers just fine. I actually have it lowered 3db from there (all the way to -8) because my domestic tranquility is improved wink.gif

You are right Batpig - the +/- 3.5dB range is fairly arbitrary and I have always said so - it could just as easily be, say -5.0db/+4.5dB. But you have to set an 'ideal' range somehow and +/-3.5dB is where I chose to set it for the FAQ. It actually came from Ed Mullen (I think it was Ed) of SVS who suggested it a long time ago as being a 'good' range to aim for. I suspect Ed knows more about subwoofers than many of the other members in this thread.

 

FWIW I aim for a sub trim during calibration of -5dB (which I achieve by setting the test tone a few dB higher than the suggested range in Pro) - this is precisely for the reason you mention - that it then enables me to run it a little hot later - up to +3dB in fact. If I followed Feri's 'advice', and achieved +11dB and thought that was fine, I would not have the option of running 3dB hot. 

 

It seems to me a pointless discussion. There is clearly nothing wrong at all with aiming for +/-3.5dB and it has several benefits - the one you have just mentioned, the ability to wake the sub up from auto-off and also the potential to reduce overdriving of the sub's input, which Feri categorically says cannot happen. How he knows this without knowing the output level of every AVR and the input sensitivity of every sub is beyond me, but he asserted it was so without the possibility of exception: "A SW pre-out signal can not clip, an AVR can not deliver "extreme" voltages even at the higher end of the trim allowance."

post #59182 of 70896
Quote:
Originally Posted by Patrick Murphy View Post

Quote:
Originally Posted by batpig View Post

Yes, this is the most often cited reason. Personally, I think the +/- 3.5db think seems a bit arbitrary in its specificity. All of these arguments we are working through are generalized, so I don't see why it's +/- 3.5 as opposed to, say, +/-5 or 6. My sub comes in at -5 typically with the gain knob at 1/2 way, and it doesn't bother me since the auto on triggers just fine. I actually have it lowered 3db from there (all the way to -8) because my domestic tranquility is improved wink.gif

I searched 'Ask Audyssey' and this is what Chris had to say;

"There is no need to worry about getting the speakers to have 0 dB level adjustment. The whole point of calibrating is to let Audyssey measure and automatically set the levels. As long as the sub level is not out of the range that the AVR can handle (–12 dB for most AVRs) then you are fine. This "need" to get the sub close to 0 dB is one of those silly internet myths that have no basis (imagine that!)."

June 26, 2012 04:19 pm

https://audyssey.zendesk.com/entries/74454-bass-management-and-lfe-not-the-same-thing

 

I agree with that. There is absolutely no need to try to achieve 0dB. A range of +/- 3.5dB or thereabouts is fine.  You will also see that Chris specifically mentions the minus range (he says -12dB) and says nothing about the positive range, which is where the possible danger of overdriving the sub input occurs. He also doesn’t mention that a setting of -12dB would almost certainly not trigger the auto-on that many people use.

post #59183 of 70896
Quote:
Originally Posted by kbarnes701 View Post

It's a good point and it is also mentioned in the FAQ as a reason to aim for a trim towards the centre values. Feri is on one of his crusades again smile.gif

How many times do I have to repeat Keith that there are no center values for trims.

There are no center values for trims.
There are no center values for trims.
There are no center values for trims.
There are no center values for trims.
There are no center values for trims.
There are no center values for trims.
There are no center values for trims.
There are no center values for trims.
There are no center values for trims.
There are no center values for trims.

And once more:

THERE ARE NO CENTER VALUES FOR TRIMS!!!!!!!!!!!!!!!!
post #59184 of 70896
Quote:
Originally Posted by kbarnes701 View Post

I agree with that. There is absolutely no need to try to achieve 0dB. A range of +/- 3.5dB or thereabouts is fine.

I can't beleive this Keith!

Chris K. said: "As long as the sub level is not out of the range that the AVR can handle (+/–12 dB for most AVRs) then you are fine." smile.gif
post #59185 of 70896
Quote:
Originally Posted by kbarnes701 View Post

I agree with that. There is absolutely no need to try to achieve 0dB. A range of +/- 3.5dB or thereabouts is fine.  You will also see that Chris specifically mentions the minus range (he says -12dB) and says nothing about the positive range, which is where the possible danger of overdriving the sub input occurs. He also doesn’t mention that a setting of -12dB would almost certainly not trigger the auto-on that many people use.

Chris made a typo, it should read +/- 12 dB as he mentions the range the AVR can handle.
post #59186 of 70896
Quote:
Originally Posted by mogorf View Post

Quote:
Originally Posted by kbarnes701 View Post

I agree with that. There is absolutely no need to try to achieve 0dB. A range of +/- 3.5dB or thereabouts is fine.

I can't beleive this Keith!

Chris K. said: "As long as the sub level is not out of the range that the AVR can handle (+/–12 dB for most AVRs) then you are fine." smile.gif

Now you are having to resort to doctoring the quotes of others!  Really Feri. The quote above clearly says -12dB.

 

BTW, Chris isn't God you know. He only ever answers what he wants to answer. I doubt if he would include in an answer the possibility of Audyssey destroying your sub by, for example, allowing the AVR to clip the sub input. And you must recall that more than one member has reported sever sub overdriving after running Audyssey.

post #59187 of 70896
Quote:
Originally Posted by mogorf View Post

Quote:
Originally Posted by kbarnes701 View Post

It's a good point and it is also mentioned in the FAQ as a reason to aim for a trim towards the centre values. Feri is on one of his crusades again smile.gif

How many times do I have to repeat Keith that there are no center values for trims.

There are no center values for trims.
There are no center values for trims.
There are no center values for trims.
There are no center values for trims.
There are no center values for trims.
There are no center values for trims.
There are no center values for trims.
There are no center values for trims.
There are no center values for trims.
There are no center values for trims.

And once more:

THERE ARE NO CENTER VALUES FOR TRIMS!!!!!!!!!!!!!!!!

 

Repetition doesn't automatically make something right. I agree that there is no purpose in aiming for a centre value (0dB). I suggest the range of +/- 3.5dB approx for the many benefits such a range brings. These are:

 

  1. Using a setting right at the negative end of the trim may cause the sub to not wake up from auto-off.
  2. Using a setting at either extreme allows for no possibility of further adjustment later.
  3. Using an extreme positive setting may clip the input of the subwoofer, which will make it sound bad and may also damage it.

 

 

If a member follows the 'Feri way' and achieves a trim of -12dB then he may have a problem under 1) above.

 

If a member follow the 'Feri way' and achieves a trim of -12dB or +12dB he will have a problem under 2) above.

 

This member did follow the 'Feri way' and destroyed his sub due to clipping its input by using an extreme setting of trim value.

 

Your way has no real benefits at all - my way has several.

 

If I have got that wrong, can you provide a similar list to the one above showing the benefits you will get if your sub trim is +12db or -12dB?

post #59188 of 70896
Quote:
Originally Posted by kbarnes701 View Post

Now you are having to resort to doctoring the quotes of others!  Really Feri. The quote above clearly says -12dB.

BTW, Chris isn't God you know. He only ever answers what he wants to answer. I doubt if he would include in an answer the possibility of Audyssey destroying your sub by, for example, allowing the AVR to clip the sub input. And you must recall that more than one member has reported sever sub overdriving after running Audyssey.

I was waiting for your recurring line: "Chris is biased". tongue.gif
post #59189 of 70896
Quote:
Originally Posted by mogorf View Post

Quote:
Originally Posted by kbarnes701 View Post

I agree with that. There is absolutely no need to try to achieve 0dB. A range of +/- 3.5dB or thereabouts is fine.  You will also see that Chris specifically mentions the minus range (he says -12dB) and says nothing about the positive range, which is where the possible danger of overdriving the sub input occurs. He also doesn’t mention that a setting of -12dB would almost certainly not trigger the auto-on that many people use.

Chris made a typo, it should read +/- 12 dB as he mentions the range the AVR can handle.

 

You can read Chris's mind!!  Now that explains a lot :)

post #59190 of 70896
Do us all a favor and give it a rest, guys. Or take it to a PM discussion.
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