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a very long post about sub/avr tuning but very very cool if u get a chance to read it.

https://www.avsforum.com/forum/113-...bration-bass-preferences.html#/topics/2958528
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Cool, I read the post but I don't think it's as complicated as they're making it out to be.

Basically your receiver is outputting the signal at one volume and the speaker (subwoofer) is set to another volume, and if you multiply the two, that's the actual volume.

It's the same thing as having a pair of computer speakers (with their own volume control) plugged into your computer. If you set your computer to 50% volume, and the speakers to 50% volume, then the actual volume you hear is obviously going to be 25%. (That's not exactly how the math works but it's good enough to understand what's going on.)

If you turn the volume way down on the computer, then you have to turn the volume way up on the speakers to get a useful total. That means the signal from the computer is kinda crap, because it's a low level and very close to the noise floor, so it's unnecessary noisy. And plus it's lower resolution. And plus you have to run the amp on the speakers closer to its maximum level, which is the zone where amps perform the worst. So the result is that you're hearing static when it's supposed to be silent and the amp is probably distorting.

So that's why it's much better to run at ~80% volume from your computer (to avoid distortion from the DAC) and control the volume with the knob on the computer speakers.

Similarly, it's going to be better to run your receiver subwoofer level closer to 0 and control its volume with the volume knob on the back of the subwoofer. Exactly how much better, who knows, but it's theoretically better. The only reason you'd want to run at less than 0 is if you think you'll need to turn the subwoofer volume up via the receiver, and I'm not sure why you would even want to do that, unless you're running Audyssey again or something. Otherwise just use the knob?
 

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This is correct. Plus, it will also force the AVR to use more power by having to output those lower frequencies through the mains, so setting them to small (80Hz)/LFE will definitely yield a much cleaner response. Another reason why having a powered sub is useful, as it helps eliminate using AVR power unecessarily. Hence, the reason why it's recommended keeping the sub trim level in the negative numbers. ...
I was following you up until the part of the sub trim level. Is this not just a volume control for the subwoofer? Maybe I'm missing something here.
 

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This is correct. Plus, it will also force the AVR to use more power by having to output those lower frequencies through the mains, so setting them to small (80Hz)/LFE will definitely yield a much cleaner response. Another reason why having a powered sub is useful, as it helps eliminate using AVR power unecessarily. Hence, the reason why it's recommended keeping the sub trim level in the negative numbers. ...
I was following you up until the part of the sub trim level. Is this not just a volume control for the subwoofer? Maybe I'm missing something here.
I believe the issue was to avoid clipping the signal somewhere in the chain, because post-Audyssey we usually raise sub levels; some of us, a lot. Your points about signal to noise are valid, I just don't know if that makes a real-world difference in this case.
 

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from everything i’ve read or been told so far is to set it (currently Have it this way but i’ve tried it both)LFE+ main, small with crossover at 80Hz


for denon if the speakers are set to small the all the LFE and anything the speakers would play below the 80hz cross go to the sub, giving exrta power for unused bottom end that crossed to the top end above the 80hz cross.

also sending all sub 80hz from the main speakers to the sub and in my case the sub handles it much better the the towers do

if i set it to lfe+main large then the sub still plays both like before but the speakers don’t have a crossover and they also try to play everything and in my case it sounds very muddy and distorted (still learning terms)
This is correct. Plus, it will also force the AVR to use more power by having to output those lower frequencies through the mains, so setting them to small (80Hz)/LFE will definitely yield a much cleaner response. Another reason why having a powered sub is useful, as it helps eliminate using AVR power unecessarily. Hence, the reason why it's recommended keeping the sub trim level in the negative numbers.

Also, whenever you're using the small/LFE crossover settings, your speakers/subs are still playing those other frequencies. They're just rolling off/increasing at the 80Hz crossover point. So it's not like there's a complete shut-off/brick wall effect happening.
And the main reason it will sound cleaner is because you're avoiding running multiple bass sources that are not time aligned and summed, and are located in different parts of the room. With LFE + Main, you're going to get constructive and destructive interference at various frequencies that will wreck any chance at a smooth bass response.
 

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I believe the issue was to avoid clipping the signal somewhere in the chain, because post-Audyssey we usually raise sub levels; some of us, a lot. Your points about signal to noise are valid, I just don't know if that makes a real-world difference in this case.
Not only signal-to-noise, but turning the volume up on the subwoofer just to amplify a weak signal from the receiver is not optimal either. Amps distort more when turned up more. So there are multiple reasons to not turn down the subwoofer volume via the receiver.

As long as the subwoofer trim isn't set to a positive number on the receiver, I assume clipping is impossible. So what would the disadvantage be to just setting it to 0 and adjusting the subwoofer volume with the knob on the subwoofer?
 

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I believe the issue was to avoid clipping the signal somewhere in the chain, because post-Audyssey we usually raise sub levels; some of us, a lot. Your points about signal to noise are valid, I just don't know if that makes a real-world difference in this case.
Not only signal-to-noise, but turning the volume up on the subwoofer just to amplify a weak signal from the receiver is not optimal either. Amps distort more when turned up more. So there are multiple reasons to not turn down the subwoofer volume via the receiver.

As long as the subwoofer trim isn't set to a positive number on the receiver, I assume clipping is impossible. So what would the disadvantage be to just setting it to 0 and adjusting the subwoofer volume with the knob on the subwoofer?
It would be a good question to ask in the Audyssey (2) thread. I would like to see the answer.
 

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Not only signal-to-noise, but turning the volume up on the subwoofer just to amplify a weak signal from the receiver is not optimal either. Amps distort more when turned up more. So there are multiple reasons to not turn down the subwoofer volume via the receiver.

As long as the subwoofer trim isn't set to a positive number on the receiver, I assume clipping is impossible. So what would the disadvantage be to just setting it to 0 and adjusting the subwoofer volume with the knob on the subwoofer?
It would be a good question to ask in the Audyssey (2) thread. I would like to see the answer.

@motrek, I'm not sure where you're getting your information on sub calibration settings using the AVR's room correction software. What's being suggested here has nothing to do with weak signals from the receiver. Nor have there been suggestions to turn down the sub via the AVR's trim level. It's the complete opposite of that.

The whole idea is to give yourself plenty headroom on the AVR to bump the trim level up 3-5db hot if you want to...which most people want to. And thus far I haven't heard of anybody complaining about damaging their subs by following this method...EVER! Myself included, as that's where I run my sub.

Where you adjust your sub's gain level to achieve a -9/-10db trim level post calibration is going to vary depending on where your sub is placed, and how far from the MLP it is. I've never heard of anyone having to turn their gain to max in order to achieve this. Although, I have heard of people running their subs at max gain and adjusting the trim to compensate, but that's a rare few. Even Ed Mullen/SVS President told them that it wouldn't hurt anything so long as you're not overdriving the sub's driver.

Also, I've always been told that you want to have a cut off point on the the trim level at around -5db. Why this is, I really don't recall. I've just always followed the recommendations given by those who know more than me. Lol
 
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@motrek, I'm not sure where you're getting your information on sub calibration settings using the AVR's room correction software. What's being suggested here has nothing to do with weak signals from the receiver.
I'm not saying anything about room correction software. All I'm talking about is increasing the signal from the receiver and turning the sub's amp down in order to get the exact same effective volume.

Correct me if I'm wrong, but if you have the subwoofer trim set to -10dB on your receiver, isn't the signal to the subwoofer 10dB less than what it would be if you had the trim set to 0? How is that not a weaker signal?

Nor have there been suggestions to turn down the sub via the AVR's trim level. It's the complete opposite of that.
And yet people on this thread are suggesting that it's a good idea to run at -10dB trim, which means that the subwoofer is turned down by -10dB at the receiver, right?

The whole idea is to give yourself plenty headroom on the AVR to bump the trim level up 3-5db hot if you want to...which most people want to. And thus far I haven't heard of anybody complaining about damaging their subs by following this method...EVER! Myself included, as that's where I run my sub.
Okay, great, set up your receiver and subwoofer however you want. If you want to be able to occasionally turn up the subwoofer volume on your receiver, great. In that case you will need to run with some negative trim normally. I don't see how that's better than using the knob on the back of the subwoofer but it's your equipment.

Where you adjust your sub's gain level to achieve a -9/-10db trim level post calibration is going to vary depending on where your sub is placed, and how far from the MLP it is. I've never heard of anyone having to turn their gain to max in order to achieve this. Although, I have heard of people running their subs at max gain and adjusting the trim to compensate, but that's a rare few. Even Ed Mullen/SVS President told them that it wouldn't hurt anything so long as you're not overdriving the sub's driver.
I never said anything about max gain. But it's a well-understood property of amps that, as you turn up the volume/amplification, distortion increases. You don't have to turn an amp to max in order to get distortion.

So the scenario we're talking about is that somebody is running at -10dB trim on their receiver. Okay great. They could achieve same result by setting the trim on the receiver to 0 and then turning down the subwoofer amplifier to 10% of what it was set at. (Remember that 10dB requires 10x the power.)

So you get a stronger signal from the receiver (10x the amplitude = much better resolution and signal:noise ratio) going to the subwoofer, and the subwoofer's amp only has to work 1/10th as hard, and you end up with the same effective subwoofer volume. The only practical difference is that if you want to increase the volume of the sub, you have to stand up and go turn a knob instead of press a button on your remote. I know which I would choose, is all I'm saying.
 

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It would be a good question to ask in the Audyssey (2) thread. I would like to see the answer.
If you're talking about Audyssey, then yeah, you'll want to turn the subwoofer volume up in order to give Audyssey a wider range of potential subwoofer volumes to work with.

But it sounds like Audyssey does a crap job with subwoofer volume anyway, if people keep having to turn up their subwoofers after running Audyssey.

So all I'm saying is, set the subwoofer trim to 0 and adjust its volume with the knob after running Audyssey. If you were going to change the subwoofer's volume anyway, then why not.
 

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Discussion Starter #150 (Edited)
If you're talking about Audyssey, then yeah, you'll want to turn the subwoofer volume up in order to give Audyssey a wider range of potential subwoofer volumes to work with.



But it sounds like Audyssey does a crap job with subwoofer volume anyway, if people keep having to turn up their subwoofers after running Audyssey.



So all I'm saying is, set the subwoofer trim to 0 and adjust its volume with the knob after running Audyssey. If you were going to change the subwoofer's volume anyway, then why not.


ideally it should be -5 not -10, the -5 is recommended even by SVS so that is never has the chance of running over 0.0 and only uses power from the sub amp and NEVER the avr power to push it.

like if i have my sub trim set to 0.0 and i also have DEQ enabled (like i do) where it will sent a small bass boost when i’m not running my MV at a ref level of 0.0 that’s what you technically don’t want cuz at that point it steels power from the av.
your better off running -5 and if it needs to take a little it will take it from the extra amp power and not the avr.

i also read if your at 0.0 trim and certain songs or movies are recorded differently it can use more then just the amp and also take from the avr and push u over into the positives.

edit:
also yes i will be adjusting my sub through the knob anyway.

what audyssey does is make sure every speaker including the sub is at 75db so if my gin is a little high it just holds on to that exrta power at the avr to make it 75 also.
 

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If you're talking about Audyssey, then yeah, you'll want to turn the subwoofer volume up in order to give Audyssey a wider range of potential subwoofer volumes to work with.

But it sounds like Audyssey does a crap job with subwoofer volume anyway, if people keep having to turn up their subwoofers after running Audyssey.

So all I'm saying is, set the subwoofer trim to 0 and adjust its volume with the knob after running Audyssey. If you were going to change the subwoofer's volume anyway, then why not.
After calibrating to 75dB (step 1), Audyssey typically returns a negative sub value. It can be anywhere from -1 to -10 in my experience. It's rare that you end up around 0.

What hasn't been mentioned in this discussion is that Audyssey is creating filters to adjust the amplitude of each frequency of your sub (step 2). Whether you end up at a volume of 0 and a weak boost to the bass portion of the curve, or -10 and a strong boost, it's all in the target curve. Either way, the total signal going to the sub is the same (step 3). That is where the difference is, not on the volume knob.
 

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@rbfastback,

Here are some links to threads that will help you with tweaks to get things dialed in. It's alot of reading, but the information documented will help you out tremendously. Make sure to read through the info given on these prior to asking questions.

The 1st link is for the Official 2017 Denon AVR Thread. This will give you specifics on your X3400H, and you should be able to get plenty of feedback from people who actually own your AVR as well.
https://www.avsforum.com/forum/90-receivers-amps-processors/2794073-official-2017-denon-s-series-x-series-avr-owner-s-thread-faq-posts-1-8-a.html

The 2nd link is the Offical Audyssey Thread.
https://www.avsforum.com/forum/90-receivers-amps-processors/2376770-official-audyssey-thread-part-ii.html

Lastly, this is the Guide to Subwoofer Calibration and Bass Preferences. This guide also has helpful tips on running your Audyssey calibration.
https://www.avsforum.com/forum/113-subwoofers-bass-transducers/2958528-guide-subwoofer-calibration-bass-preferences.html

@jdsmoothie, @kbarnes701, and @mthomas47 have shared a ton of knowledge and put a lot of time & effort into these guides to help folks like us get the most out of our systems, so this is where you will get the best info to get to where you want to be. :)


Darrell
I'm not saying anything about room correction software. All I'm talking about is increasing the signal from the receiver and turning the sub's amp down in order to get the exact same effective volume.

Correct me if I'm wrong, but if you have the subwoofer trim set to -10dB on your receiver, isn't the signal to the subwoofer 10dB less than what it would be if you had the trim set to 0? How is that not a weaker signal?



And yet people on this thread are suggesting that it's a good idea to run at -10dB trim, which means that the subwoofer is turned down by -10dB at the receiver, right?



Okay, great, set up your receiver and subwoofer however you want. If you want to be able to occasionally turn up the subwoofer volume on your receiver, great. In that case you will need to run with some negative trim normally. I don't see how that's better than using the knob on the back of the subwoofer but it's your equipment.



I never said anything about max gain. But it's a well-understood property of amps that, as you turn up the volume/amplification, distortion increases. You don't have to turn an amp to max in order to get distortion.

So the scenario we're talking about is that somebody is running at -10dB trim on their receiver. Okay great. They could achieve same result by setting the trim on the receiver to 0 and then turning down the subwoofer amplifier to 10% of what it was set at. (Remember that 10dB requires 10x the power.)

So you get a stronger signal from the receiver (10x the amplitude = much better resolution and signal:noise ratio) going to the subwoofer, and the subwoofer's amp only has to work 1/10th as hard, and you end up with the same effective subwoofer volume. The only practical difference is that if you want to increase the volume of the sub, you have to stand up and go turn a knob instead of press a button on your remote. I know which I would choose, is all I'm saying.
I think it would be more helpful for you to read up on these threads that I posted for the OP, as it might help you to better understand what is being discussed here. This way people aren't having to repeat themselves.

I want you to don't get the wrong idea about me here, so don't think I'm trying to be an *******. It's just a pet peave that I have when it comes to having to repeat myself, and it's apparent that you need more info about what we're discussing in regards to proper sub calibration using today's AVR's. So no offense.
 

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If you're talking about Audyssey, then yeah, you'll want to turn the subwoofer volume up in order to give Audyssey a wider range of potential subwoofer volumes to work with.

But it sounds like Audyssey does a crap job with subwoofer volume anyway, if people keep having to turn up their subwoofers after running Audyssey.

So all I'm saying is, set the subwoofer trim to 0 and adjust its volume with the knob after running Audyssey. If you were going to change the subwoofer's volume anyway, then why not.
Here's why. Let's say you run Audysey and it sets sub to -8. This is a good setting, and won't result in low voltage from the AVR, because we don't leave it at -8. We turn it up to -3, or -1, or 0. Now the sub is calibrated hot to our taste without any chance of clipping the output from the AVR, which can happen as volume goes up with sub trim set up in the positive range.

Your solution of just turning up the gain on the back of the sub is a bad idea for several reasons. First, you can't turn up the sub from the MLP to hear what you are doing, so you are turning it up blindly. Whereas from your couch, when calibrated to -8 or whatever, you can turn it up and listen to it as you do so. More practical. More importantly, this allows you to turn up the sub a KNOWN amount in dB. When you just turn the gain knob some random amount, did you just turn the sub up 3 dB, 5 dB, 10 dB, 20? Plenty of folks either with poor responses or who are used to super boom car audio who have done this and ran into problems.

So calibrating the sub far into the negative range on the AVR lets you run the sub quite hot without going above 0, which will reduce or eliminate the chance of clipping the output signal from the AVR and allows the user to turn the sub up a known, exact amount. And the end result is that the sub trim will be close to zero anyways, so its NOT a very low level noisy signal.
 
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ideally it should be -5 not -10, the -5 is recommended even by SVS so that is never has the chance of running over 0.0 and only uses power from the sub amp and NEVER the avr power to push it.

like if i have my sub trim set to 0.0 and i also have DEQ enabled (like i do) where it will sent a small bass boost when i’m not running my MV at a ref level of 0.0 that’s what you technically don’t want cuz at that point it steels power from the av.
your better off running -5 and if it needs to take a little it will take it from the extra amp power and not the avr.

i also read if your at 0.0 trim and certain songs or movies are recorded differently it can use more then just the amp and also take from the avr and push u over into the positives. ...
No worries about the AVR powering the sub, it's just sending a signal to the sub. The sub uses wall power to create a new (bigger) signal based on the input signal; at no point is the AVR sending any meaningful amount of power to the sub.

The concern with positive trim levels is clipping:

https://en.wikipedia.org/wiki/Clipping_(audio)

So you don't want positive trim levels because let's say you have a source signal where some of the peaks in the signal are already as big (loud) as possible. The AVR can't make those peaks any louder, by definition. So the peaks get chopped off in a way that can damage amps and speakers.

If you have trim set to 0 then you shouldn't be able to clip, or at least that seems like the definition of what trim is supposed to mean.

Setting trim to -5 and adjusting the sub's volume to whatever you want seems like a good middle ground. -10 seems like too much to me. Decibels are exponential so there's actually a huge difference between -10 and -5.
 

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Here's why. Let's say you run Audysey and it sets sub to -8. This is a good setting, and won't result in low voltage from the AVR, because we don't leave it at -8. We turn it up to -3, or -1, or 0. Now the sub is calibrated hot to our taste without any chance of clipping the output from the AVR, which can happen as volume goes up with sub trim set up in the positive range.
I'm confused. It sounds like you're disagreeing with me but you're literally repeating exactly what I wrote: turn up the sub volume, run Audyssey, presumably it gives you some negative trim value. Set the trim to zero, turn down the sub volume to taste. We're saying exactly the same thing.
 

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I think it would be more helpful for you to read up on these threads that I posted for the OP, as it might help you to better understand what is being discussed here. This way people aren't having to repeat themselves.

I want you to don't get the wrong idea about me here, so don't think I'm trying to be an *******. It's just a pet peave that I have when it comes to having to repeat myself, and it's apparent that you need more info about what we're discussing in regards to proper sub calibration using today's AVR's. So no offense.
No offense taken. Actually I just read that link on subwoofer calibration and nothing in the article disagrees with anything I've been saying. Basically the article says that the only reason to run with negative trim (instead of 0) is so that you can easily adjust the subwoofer volume via your receiver's remote control, which the author of the article seems to think is more convenient.

So actually I'm going into a bit more depth than the article, because there are actual technical reasons why it's undesirable to run with a lot of negative trim (like -10dB) which the author doesn't go into.
 

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No offense taken. Actually I just read that link on subwoofer calibration and nothing in the article disagrees with anything I've been saying. Basically the article says that the only reason to run with negative trim (instead of 0) is so that you can easily adjust the subwoofer volume via your receiver's remote control, which the author of the article seems to think is more convenient.

So actually I'm going into a bit more depth than the article, because there are actual technical reasons why it's undesirable to run with a lot of negative trim (like -10dB) which the author doesn't go into.
But it has been stated that regardless of it being -10 or 0, it's still the same output from the sub, and with having it at -10db post calibration, it gives you the headroom to run it 3-5db hot using the trim level...which most people do.

...and i just repeated myself. :p

All kidding aside, the methods that I'm referring to are what has been recommended on these forums long before I joined, so apparently they're pretty solid. If they didn't work for myself and all of the other members that have had success with them, I wouldn't be passing along the information to newbies that join us here on AVS.

The single most important thing about this site that keeps me coming back is the vast amounts of knowledge that can be had from either reading, or from some great people that are more than willing to take time out of their day to help us out. It really is a great community.
 
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If you're talking about Audyssey, then yeah, you'll want to turn the subwoofer volume up in order to give Audyssey a wider range of potential subwoofer volumes to work with.

But it sounds like Audyssey does a crap job with subwoofer volume anyway, if people keep having to turn up their subwoofers after running Audyssey.

So all I'm saying is, set the subwoofer trim to 0 and adjust its volume with the knob after running Audyssey. If you were going to change the subwoofer's volume anyway, then why not.
I'm confused. It sounds like you're disagreeing with me but you're literally repeating exactly what I wrote: turn up the sub volume, run Audyssey, presumably it gives you some negative trim value. Set the trim to zero, turn down the sub volume to taste. We're saying exactly the same thing.
The post I quoted didn't make it sound like thats what you were saying at all. You stated that people have to turn their subs UP after Audysey, which is true. Then you said calibrate in such a way that AVR trim comes out at 0 and adjust sub gain from there. This means you would then turn the sub UP to taste(since it will be set low).

For the sake of clarity, I'm saying it is correct to adjust subwoofer gain in such a way as to achieve an AVR subwoofer trim level of around -9 dB when running Audysey. Then, using the AVR subwoofer trim adjustment, increase the sub level to taste from the listening position. This increases subwoofer level an exact, known amount while being able to hear the incremental changes, rather than a random, unknown amount using the gain knob on the sub.
 

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But it has been stated that regardless of it being -10 or 0, it's still the same output from the sub, and with having it at -10db post calibration, it gives you the headroom to run it 3-5db hot using the trim level...which most people do.

...and i just repeated myself. :p
...
Right. Great. Like I said, run your stuff however you want. If you want the "convenience" of turning up your subwoofer volume via your receiver then that's what you'll have to do.

Just understand that your signal from the receiver to the sub will have less resolution and a worse signal:noise ratio. And the sub's amp will have to be set higher which almost certainly means more distortion. If these are trade-offs that you (and "most people") are willing to make, then fine.

Of course it's possible that none of this really makes an audible difference. You don't need a lot of resolution to accurately reproduce a bass signal, and similarly, most noise is going to be inaudible when played through a subwoofer. (Since they can't play higher frequencies.) And most higher-quality amps don't audibly distort until you get past their 80% range, so as long as you don't have your subwoofer volume turned to maximum, you probably won't notice any distortion.

But, speaking as an electrical engineer, give me the cleanest possible signal and the most possible amp headroom all day long...
 
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