What uses more power bass or treble

Measure the AV receiver and optimize the settings

AV receivers have gotten pretty smart over the past decade. In order to offer you the best possible sound, they analyze the placement of your speakers and the acoustics of your room. To do this, they use an automatic calibration system. A measurement microphone and a little math are sufficient for the AV receiver to significantly improve the sound impression after the measurement.

The calibration works a little differently for every manufacturer or calibration system. There is therefore no reliable, generally applicable explanation. You should therefore always read the operating instructions for your AV receiver before measuring. The following description serves as a basic knowledge and as a cross-check whether your approach makes sense.

I assume that you

The placement of the subwoofer is a topic in itself. If the bass is not satisfactory after measuring, check the settings of the subwoofer and those of the AV receiver. If that doesn't reveal any major mistakes, you can wonder whether another location would not be more suitable for the subwoofer.

Have the AV receiver measured

I am assuming that you have an AV receiver with a calibration system (if not, you can read below about how to manually edit the settings). You should find information about this in the product description or user manual. The safest identification feature is if a small measurement microphone was supplied with the AV receiver.

The measurement microphone

However, a microphone is not always included in the scope of delivery. In particular, cheaper models sometimes only offer the Connection option for a measurement microphone - the microphone itself can be a special accessory. It's always one separate connection, not one of the typical cinch inputs on the back.

There are qualitatively much better measurement microphones than those that are supplied with AV receivers. As a rule, however, you can only use the microphone provided. Even if the connections were compatible, the AV receiver is still on be Measurement microphone set. Another microphone would falsify the measured values ​​and thus lead to incorrect settings.

The measuring microphone only remains connected until the calibration is finished. It can then disappear in the closet until something fundamental changes in your home theater: new speakers, a different layout, improvements to the room acoustics or a shift in the seats.

One point measurement

The measurement microphone is set up at the later listening position. Three things are important:

  • It has to be halfway exactly where your head will be later. Keep in mind that some cinema seats tilt back when someone is actually sitting in them.
  • The microphone should be as horizontal as possible - not just hanging over the headrest with the cable.
  • It should have neither a reflective nor an absorbent surface behind or under it. So no board, no cardboard box, but also no pillow.

Most measurement microphones have a thread that fits on camera tripods. So you can place it very well on a cinema seat. Keep a distance from the headrest while doing this.

When the right place has been found, the measurement can begin. To do this, follow the instructions for use.

During the measurement you either go out of the room or at least sit down somewhere on the floor, preferably behind the sitting position. You must not be between a loudspeaker and the microphone so as not to affect the room acoustics too much.

What happens when measuring?

You will hear a series of whistling tones from each speaker that start very low and get higher and higher. The AV receiver thus plays the entire relevant frequency spectrum. He immediately picks up the sound again via the measuring microphone and compares the differences between the transmitted and received signal.

The measurements tell the AV receiver the following:

  • Based on the time it takes for the signal to be received again, it recognizes how far away each loudspeaker is from the listening position.
  • From the volume he can tell whether the loudspeaker needs to be corrected a few dB up or down compared to the others.
  • The frequency response shows which tones the loudspeaker reproduces louder or quieter. With this he can create a correction curve for the internal equalizer.

In addition, it recognizes below which frequency the loudspeaker no longer plays powerfully enough and can thus determine the appropriate crossover frequency from which the subwoofer should later take over.

Measure at several points

Some AV receivers offer the ability to take measurements at multiple points. Between the measurements, the AV receiver will ask you to move the measurement microphone to the next position.

You decide which seats to choose based on the frequency with which they are used. The space that is used most often is the first measurement position. The second most frequently used space is measured second, and so on. I assume that the main position is in the middle. The more spectators there are, the more seats are occupied from the inside out. So you don't measure all the places from left to right, but rather like this:

  1. center
  2. left of center
  3. right of center
  4. two left of center
  5. two to the right of center
  6. etc.

The AV receiver will calculate an average value from the various measurements and adjust its settings accordingly. However, the distances are only determined during the first measurement.

The whole thing is an attempt to optimize it for several seats. "Try" because the optimization of the settings is only for one Seat is possible. The additional measurements only have the effect that the AV receiver weakens the optimizations made for place 1 in favor of the other places so that it does not have such a negative effect there. In doing so, however, the optimum for the main position is lost.

The best way to decide whether you want to measure at several points is based on two criteria:

  1. Will the home theater be used primarily by one person or by several? If you are multi-person watching a lot of the movies, it is a good idea to optimize for multiple seats.
  2. What do the settings look like after the measurements? Utter chaos? Incomprehensible values? Then it's better to measure at one point only.

Special specifications for several measuring points

Some AV receivers or calibration systems make special specifications for several measuring points. Pay attention to the description in the operating instructions again.

A manufacturer-independent representative, on the other hand, is the so-called Scheme 101, where the measuring points are not only based on the seats.

Instead, measurements are taken at various points on the main seat. The distance to the first measuring point is only a few centimeters. More seats will only be added later.

  1. exact seating position at the main seat
  2. like 1, but 8 cm forward
  3. like 1, but 8 cm upwards
  4. like 1, but 8 cm forwards and upwards
  5. like 1, but 8 cm to the left
  6. like 1, but 8 cm to the right
  7. exact sitting position at the seat on the left
  8. exact seating position at the seat on the right

The aim of these closely spaced measuring points is to eliminate inaccuracies caused by local disturbances. The example shows that it is not possible to make a generally valid statement about the distribution of the measuring points. So, based on your seats, decide what makes sense.

Special features in the search for the measuring point

If your main seat is not exactly in the middle between the speakers, this begs the question of whether you shouldn't measure exactly in the middle, regardless of the seats. Then you would at least have symmetrical settings, which may not be ideal for position 1, but position 2 is not that bad.

How you find the main measuring point is again based on the use of the home theater. If you and your guests are always sitting somewhere else anyway, or if you can't even make out an exact seat (sofa), it might be best to measure in the center of the speaker setup. The distance to the front should in any case correspond to that of a possible seat.

In all other cases, it is better to measure on the primary seat - especially if you use the home theater mostly on your own. Especially if the primary place is not exactly in the middle, asymmetrical values ​​come out, but they fit perfectly for this one place. The rest is at a slight disadvantage anyway.

If there are several rows of seats, it is sufficient to measure only the main row (usually the first). In any case, the back row is not ideal in the acoustic sense because of its proximity to the rear wall.

Phew, halftime. Yes, the topic is quite extensive. And the manual interventions in the measurement result only come now. If you have the feeling that you are completely on the hose, it is best to turn to our advice. This is especially true for a home theater with several rows of seats.

Check and correct settings

After the AV receiver has finished measuring, you can unplug the measurement microphone and put it aside for the time being. The AV receiver may also offer you various sound settings to choose from, which have names such as “neutral” or “natural”. If that is the case, first choose the standard setting or whatever as unadulterated as possible seems to be.

Then it's up to you to check all the settings. The AV receiver does not always make the right conclusions from its measurement results - or the measurement was simply inaccurate.

You can also go through the following settings if the AV receiver does not offer any possibility for calibration and you have to set everything by hand.

speaker

The speaker setup must be displayed correctly. Almost every AV receiver today offers a graphic representation of a virtual room with speakers. All speakers that you have connected must be visible on them. Often this setting is made before the calibration.

size

For all loudspeakers, the size can usually be selected in 2 stages: small or. small and large or. large (also: "full range" or "full band"). The AV receiver uses the frequency that a loudspeaker was able to reproduce with sufficient strength to determine whether it was large can apply.

At least that's how it should be. Misinterpretations of the measurements tend to show up here. The recommendation on how to set up your speakers is different anyway. If you have connected a subwoofer, set up all the speakers small one - even when it comes to large floor-standing speakers! Without a subwoofer, at least the front speakers should large be.

It may seem nonsensical to buy expensive floorstanding speakers, but then buy them as small to declare. But it is not. The AV receiver is relieved of the lowest frequencies - there is more power for the higher frequencies. The subwoofer does the rest. It can do that much better anyway and it brings its own amplifier for it. In addition, a single bass source is easier to get acoustically under control.

There are of course exceptions to this rule: When using a separate power amplifier, when used frequently for music or when it simply sounds much better large the better attitude. In all likelihood, however, you have already dealt with the matter more and would know which setting is appropriate.

distances

Due to the delay in the signals arriving at the measuring microphone, the AV receiver can calculate the distance between the loudspeakers and the microphone. From the distances, it in turn calculates the necessary delay time for the channel.

The purpose of the distance or the delay time is to virtually bring all loudspeakers to the same distance from the listening position. If all loudspeakers were to emit an impulse at the same moment, it should reach the listener at the same time. The delay times thus compensate for different distances.

You can subsequently measure the measured distances in the room exactly (preferably with a laser distance measuring device) and correct the values ​​set by the AV receiver with even more precise information.

But be careful: It is better not to do this with the subwoofer, active speakers or speakers that are connected to external power amplifiers with an upstream DSP. Active modules and DSPs can result in further delays which make it necessary to consciously accept apparently incorrect distance information.

If you only sit one seat further to the left or right, the distances to all loudspeakers naturally change. This only proves that an optimization of the settings is only possible for exactly one position in the room.

Background knowledge: With AV receivers that were built up until the early 2000s, you basically had to set the delay time manually by converting the distance into milliseconds based on the speed of sound. Fortunately, this is much easier today.

Volume / level

As the distance from the loudspeaker increases, so does its volume at the listening position. In addition, different levels of efficiency of the loudspeakers lead to large deviations in volume.

The AV receiver compensates for these differences by raising or lowering each individual channel by a few dB. Like the distances, the values ​​are displayed in the menu for each individual loudspeaker and can be adjusted manually afterwards.

For checking and manual correction, the AV receiver offers the option of outputting a test tone, the so-called pink noise. It rushes in each loudspeaker for a few seconds (or as long as you want). At the listening position, the noise should always sound equally loud. At the same time, this is the old, manual way of determining the correct volume, which is also completely sufficient, especially for beginners.

Sound level meter

It works better with a sound level meter that measures the volume fairly accurately at a certain point. Our ears can deceive us. With a sound level meter, the volume is clearly displayed as a number in decibels. The sound level meter should have an A and C filter, using the C filter.

The procedure is basically the same. You let the AV receiver play the pink noise and measure the volume with the sound level meter at the listening position. On the first loudspeaker, turn the volume control up so that the sound level meter shows a value around 80 dB. The same value should then be displayed for all other channels - if not, correct it accordingly in the setup of the AV receiver. Make sure there is nothing between the sound level meter and the current speaker.

Better to correct downwards than upwards

Regardless of how you make the settings, you should pay attention to the following: Individual speakers should be corrected downwards rather than upwards. An example: Instead of leaving the front at 0 dB and increasing the center to +2 dB, you should leave the center at 0 dB and lower the front to -2 dB. All values ​​should be less than or equal to 0 if possible.

The reason for this is that the increase is added to the current volume setting and so you can go above the maximum at high volumes. This can cause clipping or other unsightly effects. Damage to the speakers is one of them.

Equalizer

Many AV receivers now have a built-in equalizer that can be set separately for each channel. This is the fourth point that the AV receiver uses the measurement results for.

Equalizers are often misused to raise the sound slightly in different frequency ranges in order to support certain preferences. This is known from music players where there are predefined equalizer settings for music genres. Unfortunately, that's exactly the opposite of the point of an equalizer.

As the name suggests, it should bring all frequencies to the same volume (adjust to one another). Due to the frequency response of the loudspeakers and the room acoustics, not every frequency reaches the listening position equally loud. Some speakers are a bit too thick in the bass, others in the treble - with some models the frequency response is a total roller coaster ride. The function of the equalizer is to amplify the frequencies that are too quiet and to weaken the frequencies that are too loud.

By measuring, the AV receiver knows which frequency is how loud. To do this, it reproduces the test tone from very low to very high. From this he creates a curve that works in exactly the opposite direction. The actual frequency response in your room is straightened in this way.

Manual intervention in the frequency response

In many cases, the AV receiver offers to intervene in this curve and adapt it to your own requirements. You should only do that if you know halfway what you are doing. You can bend the sound quite a bit with it.

Normally, adjustments should only be made with the help of manual measurements of the acoustics.But that would be a chapter in itself. The measurement microphone of the AV receiver is unsuitable for this and there is still a lack of other equipment.

What, on the other hand, is possible without hesitation:

  • You can tone down the equalizer settings by making the curve a little smoother. That doesn't hurt at first if the settings seem a bit excessive in some places.
  • You can deactivate the equalizer completely or smooth the curves completely. This is not necessarily an improvement, but it is no different than if the AV receiver had no equalizer on board.

Most AV receivers also offer a Pure / Direct mode that temporarily bypasses all of these settings. This way you won't lose the settings, but you can still hear how it sounds completely unchanged.

Subwoofer

Slightly different rules apply to the subwoofer. The automatic calibration systems have their problems with subwoofers. This is not least due to the fact that the measurement microphones supplied are not the best. Overall, however, the bass is a very critical field, where a little feeling and joy in experimenting is more in demand.

distance

A distance is also set for the subwoofer. The aim is to harmonize its sound waves with those of the front speakers so that there are no cancellations. The other speakers should be on small be set and therefore do not emit too deep bass, but there is still overlap in the area of ​​the set crossover frequency.

The distance determined by the calibration system will probably not correspond to the real distance between the subwoofer and the listening position or even have a completely utopian value. The effects of the room and the inertia of the subwoofer result in delays that are difficult to understand, so that it is not always possible to understand what the AV receiver is doing there. For now, keep the value and test the result. If the bass is not right, you can always correct the value later.

When measuring, make sure that the phase regulator on the subwoofer is set to 0 °. The distance on the AV receiver and phase on the subwoofer are two settings that end up trying to do the same thing.

volume

It is very likely that the AV receiver has brought the volume of the subwoofer output to the maximum value in one direction, for example to -10 dB or +10 dB. This is a typical maximum for the correction of the individual channels. Because the subwoofer has its own volume control, it was probably set too quiet or too loud during the measurement. The range in which the AV receiver can adjust the channel is too small, and so it directly hits a limit.

If this is the case, turn the volume on the subwoofer down significantly (at a measured level of well below -5 dB) or further up (at a level well above +6 dB). Then you carry out the measurement again. (For this reason alone, it makes sense to first carry out a one-point measurement before you do the complex multi-point measurement.) You repeat this until the AV receiver levels the subwoofer in the range of 0 dB to +5 dB after the measurement. This has the advantage that the subwoofer wakes up from standby a little earlier if the signals are quiet.

further details on the settings on the subwoofer

Crossover frequency

Some AV receivers also determine the optimal crossover frequencies for all speakers. This is the frequency below which all signals from the main loudspeakers are redirected to the subwoofer - in addition to the signals from the LFE channel, which the subwoofer reproduces anyway.

The AV receiver recognizes from the measurements of the main loudspeakers from which frequency they develop their full strength. He should set the crossover frequency just above this. As a rule, this should be between 60 and 100 Hz. With very small speakers, the crossover frequency can also be higher. The setting only affects speakers that are on small are set.

If the AV receiver has not made the setting, you may need to set it manually. There should be a manufacturer recommendation for your speakers. If you can't find any information about it or have other doubts, select 80 Hz as the crossover frequency.

The automatic calibration of the AV receiver is actually not that difficult. On the other hand, it is advantageous to understand the settings that are influenced by it. Manual interventions only really make sense and make it possible to get even more out of the system. Because as good as a calibration system is, it cannot replace a little understanding of the matter.

The next step is to measure the acoustics yourself with a really professional measurement microphone. This allows even more control over the acoustic conditions and enables much better fine-tuning. But you should only do this if you want to tease out the last 20 percent.

About Bert Kößler

Passionate projectionist, popcorn cook, ticket tearer, usher, program manager, projectionist, cleaning specialist and cable man all rolled into one. Tends to be very fanatic when it comes to the control and automation of the home theater. Was able to motivate himself between two films to set up Heimkino Praxis as an outlet for occasional typing attacks. Show all posts by Bert Kößler →