[Photos and Measurements Inside] Dirac Live Distorts Bass JBL 705P

[SadMonster]

Audio Setup

Measured Frequency Response

Hi, Dirac Live calibration causes the bass on the JBL 705P to distort when playing at moderate volumes even if I set the correction target to just a completely flat line. What is happening here and can I fix it?

 

[Dimifoot]

The software pushes the loudspeaker to distortion when boosting to fill the 40-60Hz and 80-90Hz.
You need subs.

 

[Dimifoot]

Actually is 50-100Hz, just something present at 75hz

 

[abdo123]

you can click 'corrected' during filter creation to see how much will Dirac boost each dip, if your speaker doesn't have enough headroom for that then it will sound bad.

I wouldn't let Dirac add more than 10 dB with my target curve.

 

[SadMonster]

I have 2 subs they are in the picture! Also the max boost is under 10 as other guy recommended but I guess the 705P are too small to try and make up for room dips at a reasonable volume.

If I change out the JBL 705P for some cheaper but larger KRK 8 or 10 inch speakers do you think it would sound better?

Or maybe I can add 80hz low pass filter on the back of the speaker control panel in addition to the crossover and have the subs work even harder?

 

[alex-z]

I have 2 subs they are in the picture! Also the max boost is under 10 as other guy recommended but I guess the 705P are too small to try and make up for room dips at a reasonable volume.

If I change out the JBL 705P for some cheaper but larger KRK 8 or 10 inch speakers do you think it would sound better?

Or maybe I can add 80hz low pass filter on the back of the speaker control panel in addition to the crossover and have the subs work even harder?

Wait, you aren't high-passing your speakers at 80Hz? That is the entire point of owning subwoofers, to take the load off your speakers.

 

[SadMonster]

Wait, you aren't high-passing your speakers at 80Hz? That is the entire point of owning subwoofers, to take the load off your speakers.

They are already having the low range frequencies reduced by the subwoofer crossover

 

[McFly]

Where's the dirac ? on a minidsp or AVR or?

 

[SadMonster]

Where's the dirac ? on a minidsp or AVR or?

MiniDSP!!

This is the song with the most notable distortion that I’ve found, maybe it’s just a problem track or maybe even in the recording???

Distortion Bass On Right Speaker Within First 20 Seconds:

 

[McFly]

Are you exceeding -10dB on the Vol?

I believe miniDSP Dirac has a max boost of 10db built in, and if it uses it to correct, you will get digital clipping above -10dB.

You'll need to adjust your system to get gain somewhere else - can you detail the whole audio chain?

 

[SadMonster]

Are you exceeding -10dB on the Vol?

I believe miniDSP Dirac has a max boost of 10db built in, and if it uses it to correct, you will get digital clipping above -10dB.

You'll need to adjust your system to get gain somewhere else - can you detail the whole audio chain?

Yeah I’m actually at +12 db on the volume controls it doesn’t get loud enough a lot of content otherwise….

System:

TV
to
Minidsp
to
Subwoofers
to
Speakers

 

[SadMonster]

Edit: I just found out I can make the speakers way louder by setting them to -10 instead of +4 on the back should I try to recalibrate like this with the volume in Dirac control set to 0dB?

I guess I’ll try setting the volume to 0 from -12 and see if the distortion improves first

 

[SadMonster]

Are you exceeding -10dB on the Vol?

I believe miniDSP Dirac has a max boost of 10db built in, and if it uses it to correct, you will get digital clipping above -10dB.

You'll need to adjust your system to get gain somewhere else - can you detail the whole audio chain?

You are the winner!! I experimented and at the same volume level +12 on the dirac volume control is clipping and creating distortion. At -10 on the volume the situation is much better!

Now I just need to figure out if I want to recalibrate at 80hz or 120hz crossover. I've had these speakers for nearly a year and my completely no measurements impressions has always been that 120hz sounded like cleaner and more realistic bass with less boxy and more open vocals so maybe I should start there and let Dirac do it's thing...

 

[McFly]

Edit: I just found out I can make the speakers way louder by setting them to -10 instead of +4 on the back should I try to recalibrate like this with the volume in Dirac control set to 0dB?

I guess I’ll try setting the volume to 0 from -12 and see if the distortion improves first

Use -10 on the speakers to get more gain instead of pumping the minidsp volume up.

What mini dsp are you using? Ideally you wouldnt go from the subwoofer TO the speakers, rather use the miniDSP to feed the 705s and the subwoofers separately

 

[SadMonster]

Use -10 on the speakers to get more gain instead of pumping the minidsp volume up.

What mini dsp are you using? Ideally you wouldnt go from the subwoofer TO the speakers, rather use the miniDSP to feed the 705s and the subwoofers separately

I don’t remember the model but yeah I could do it like that but then I’d lose stereo bass and it would be a little more complicated to setup the wiring lol…but I am interested…

Okay for now here is the 120hz crossover measurements that sounds better to me versus the 80hz if anyone is interested in telling me why this might be

I have 3 target curves loaded to the Dirac.

1. Flat
2. Dirac Default Curve
3. Harman Curve

I need someone to help me blind test my preference ratings now but the initial impression is that the bass boosted harman curve does sound best for most content

Edit: Hmmmm actually I’ve been listening to completely flat and all sorts of other curves and I‘m not really convinced I like any better than flat right now

 

[alex-z]

I don’t remember the model but yeah I could do it like that but then I’d lose stereo bass and it would be a little more complicated to setup the wiring lol…but I am interested…

Stereo bass isn't really a thing. Below 100Hz our ears are omni-directional, you cannot distinguish the left/right subwoofer based on placement. They might sound different based on room modes, but that is a bad thing, not a good thing.

 

[SadMonster]

Stereo bass isn't really a thing. Below 100Hz our ears are omni-directional, you cannot distinguish the left/right subwoofer based on placement. They might sound different based on room modes, but that is a bad thing, not a good thing.

You were definitely right about the bass boost being better than flat! Interestingly when I set the subwoofer volume and crossover by ear before measuring - the result came pretty damn close to the harman curve!!

But I think I might be a mutant because I have always been able to tell where the subwoofer is

 

[alex-z]

But I think I might be a mutant because I have always been able to tell where the subwoofer is

Then the subwoofer crossover is too high, or not steep enough. If you can still locate the subwoofer at 80Hz with a 12dB per octave slope, that is impressive, and at 60Hz that would definitely fall into mutant territory.

Once you have both subwoofers playing together in mono, they should sound better than being in a stereo config.

 

[SadMonster]

Then the subwoofer crossover is too high, or not steep enough. If you can still locate the subwoofer at 80Hz with a 12dB per octave slope, that is impressive, and at 60Hz that would definitely fall into mutant territory.

Once you have both subwoofers playing together in mono, they should sound better than being in a stereo config.

The lowest I ever tried was 80hz but I could definitely tell then when I had a single sub. JBL says bass tends to be omnidirectional given enough distance so maybe I am too close or something. But it was actually my primary reason into looking 2 subs, didn’t learn about improve FR or whatever as a benefit until after.

 

[abdo123]

Are you exceeding -10dB on the Vol?

I believe miniDSP Dirac has a max boost of 10db built in, and if it uses it to correct, you will get digital clipping above -10dB.

You'll need to adjust your system to get gain somewhere else - can you detail the whole audio chain?

No that’s incorrect, it has no no headroom built in.

and you don’t need to put a headroom for DIRAC, just your manual filters.