Did you know thatTact-2.2 XP equal loudness compensation can be used without room correction?  

Tact-2.2 XP is designed to perform dynamic room correction that includes equal loudness curve compensation. Please see the following link.http://www.tactlab.com/DRC/drc.html

Entire dynamic room correction process consists of room response measurement, reference target curve and equal loudness (dynamic) curves design. At the end of this processTact-2.2 XP will perform full range room correction based on one reference target curve and eight dynamic target curves. When listening to music and for any volume change 2.2 XP recalculates entire room correction with correction filters that are level dependent. That is why we have named it Dynamic Room Correction.

Tact-2.2 XP can be used to evaluate just the effect of equal loudness compensation without taking in account room response measurement. This feature of 2.2 XP is important for those who would like to evaluate the effect of equal loudness compensation only, with room correction feature being excluded.

To describe the process of evaluating equal loudness compensation only we assume the following:

1.      2.2 system with 100 Hz, 24th order crossover filters

2.      Equal loudness compensation is saved in RCS/DRC preset 1

  At the end of this process equal loudness compensation effect can be evaluated by switching 2.2 XP back and forth from DRC preset 1 to bypass. When in bypass, 2.2 XP will play audio with engaged crossover filters only. When in DRC preset 1, 2.2 XP will play audio with engaged crossover filters and equal loudness compensation curve. Please note that all dynamic (equal loudness) target curves can be modified to meet your specific listening needs.

  To setup 2.2 XP for equal loudness compensation evaluation please implement the following steps.

STEP 1 – Clear preset one measurement data

  Connect your 2.2 XP to PC and make sure that RS232 communication functions properly. For more help on communication issues please use on screen help menu. Click on RCD/DRC (1) button to enter RCS/DRC screen. 

Fig. 1. Click on (1) to enter RCD/DRC screen

 On the File No panel (Fig. 2) and for RCS/DRC Preset 1 select measurement File No 1 (1). On the Action panel, engage 2.2 XP preset 1 by clicking on RCS/DRC Preset 1 button (2). Enable DRC feature and disable automatic correction by clicking on (3) and (4) respectively.

 
Fig. 2. File No and Action panel with enabled DRC ON (3) and disabled Auto Corr (4).

Click on MSR button (5) to enter the Measurement screen (Fig. 3).

 

Fig. 3. Measurement screen

 On the measurement screen select Measurement File 1 (1). In the option menu click on Clear Measurement File No. 1 option (2). This will clear measurement data saved in measurement file 1. Clearing measurement data is equivalent to having flat measurement response. Please note that we have assigned measurement file 1 to correction preset 1 (Fig. 2). Click on Exit button to close the measurement screen.

STEP 2 – Set crossover filters and target curves

In the Tools menu select Set Crossover option and set crossover filter parameters as displayed in Fig. 4.

 
Fig. 4. Preset 1 crossover filter parameters.

Place the mouse cursor over T-L and R button (1) and right mouse click to display target curve menu. Click on Load menu option (2) and load Flat.cor target curve file. This curve is supplied with your 2.2 XP software.

Fig. 5. Click on (2) to load Flat.cor target curve.

  In the File menu (Fig. 6), click on Load Dynamic Target Group menu option and load Equal_Loudness_Minus_6dB_Ref.grp dynamic target group file. This file contains a set of dynamic target curves with -6dB target curve set to 0dB. For more details please refer to on screen help menu.

 

Fig. 6. Click on (1) to load Equal_Loudness_Minus_6dB_Ref.grp dynamic target curve group file.

Make sure that all target curve and crossover buttons are enabled. Target and crossover curves should be displayed as shown in Fig. 7.

Fig. 7. Target and crossover curves.

1. 0dB dynamic target curve.
2. -6dB dynamic target curve is overlapping with the reference target curve.
3. -12dB dynamic target curve.
4. -18dB dynamic target curve
5. -24dB dynamic target curve
6. -30dB dynamic target curve
7. -36dB dynamic target curve
8. -42dB dynamic target curve
9. Low-pass crossover filter curve
10. High-pass crossover filter curve. 

Click on ENGAGE button to engage selected target curves. At this point preset 1 is set for evaluation of the effects of equal loudness compensation.

STEP 3 – Set bypass crossover filters

On the action panel select RCS/DRC Preset BP. This will place 2.2 XP into bypass mode. In bypass mode all correction algorithms are disabled.

 In the Tools menu select Set Crossover option and select crossover filter parameters as displayed in Fig. 8.

Fig. 8. BP Crossover filter parameters.

 

It is very important to have bypass and preset 1 crossover parameters exactly the same. In this way the only difference between bypass and preset 1 is equal loudness compensation. Equal loudness compensation is present only in preset 1 and not in bypass.

Listening Tests

At this point 2.2 XP is set for evaluating the effects of equal loudness compensation. Simply, play your favorite tracks and switch between bypass and preset 1. When in bypass 2.2 XP will play with only crossover filters engaged and when in preset 1, 2.2 XP will play with engaged crossover filters and equal loudness compensation.

Please note that for 2.2 XP level set at -6dB there should not be any difference between bypass and preset 1. The reason for this is that at -6dB 2.2 XP will use -6dB target curve which is set at 0dB flat line. In general, a flat target curve at 0dB means that no correction was applied to audio signal.

It is important to note that the difference between bypass and preset 1 increases as the listening level decreases. For example, if 2.2 XP level is set at -24 dB the corresponding -24dB dynamic target curve (curve 5 in Fig. 7) will be engaged. If 2.2 XP level is set at -30 dB the corresponding -30dB dynamic target curve (curve 6 in Fig. 7) will be engaged. By comparing these to dynamic target curves is obvious that -30dB dynamic target curve will produce larger boost at low and high frequencies than -24dB curve. Therefore, we can expect larger difference between bypass and preset 1 at -30dB listening level than between bypass and preset 1 at -24dB listening level.

This loaded set of dynamic target curves can be modified to match your particular listening needs. Each target curve can be modified on the fly while the music is playing. To listen to target curve modifications simply click on ENGAGE button.

Tact-2.2 XP is the only processor on the market that offers this level of sophistication. With dynamic target curves concept users can literally enter their hearing properties into their audio system.

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