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

[abdo123]

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.

Not really, if the subwoofers are not close to the speakers or at the same wall/corner they’re still localizable.

stereo subbass is stupid though indeed. I would definitely turn it to mono by having both Dirac inputs go to each of them.

 

[abdo123]

Did you gain match the subwoofers or SPL match them when you did the integration?

 

[SadMonster]

Did you gain match the subwoofers or SPL match them when you did the integration?

Gain match! Why?

 

[SadMonster]

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.

I don’t follow what this means but I was able to objectively remove the distortion by moving the volume slider from +12 to -10. Are you saying that I can get the same result with less volume loss by changing to +0DB even when I have an 5DB bass boost in my target curve?

 

[abdo123]

I don’t follow what this means but I was able to objectively remove the distortion by moving the volume slider from +12 to -10. Are you saying that I can get the same result with less volume loss by changing to +0DB even when I have an 8DB bass boost in my target curve?

Ooof YIKES.

okay time for some digital signaling basics.

no sample (or frequency) can ever go above 0dBFs, DIRAC when it applies boost understands this and would add headroom (negative gain) so no clipping would occur.

however, just because the MiniDSP sliders can go up to +12 dB doesn’t mean that you actually can increase it to +12 dB. keep all the gain settings at 0 dB unless you need to apply a bunch of boost filters manually, then you have to DROP DOWN, NEVER UP.

If you don’t have enough volume then get a beefier amplifier don’t boost the signal.

what are your MiniDSP non-Dirac settings?


Gain match your gain matched subwoofers to your mains speaker. After that make sure the speakers are playing at -4 dBFS. (-4 on the gain slider for their individual output)

and then run a DIRAC calibration.

if this is not clear then feel free to ask questions.

 

[SadMonster]

Alright since I’m not applying any boosts or cuts outside of the Dirac target curve I can safely get some more volume by setting the volume sliders to 0db!

These speakers have built in amps but I don‘t need any more volume for movies with the volume slider at 0db. At -10 I need a little more for movies though but apparently I can set to 0db so I should be fine.

Not sure what you mean when you ask what my minidsp settings are. Here is what I can tell you:
- 10DB gain on left and right channel
- No dedicated sub channel, stereo subwoofer pass through to stereo speakers.
- 3 Switchable Target Curves Progammed: Flat, Dirac Curve, Harman Curve
- No manual EQ
- Unused channels muted

I am not sure what you mean by gain match. How can I tell when the subwoofer is gain matched with the speakers?

Thank you for the help!!!

 

[abdo123]

A speaker is gain matched with subwoofers when both the speakers and the subwoofers would produce the same amount of SPL when they’re at the same location in your room.

to reach the Harman target curve it’s much easier to start with your subwoofer being 4 dB louder than your speakers. However you must gain match first.

 

[abdo123]

So, in that order:

1) gain match the subwoofers to each other, if they’re not identical

2) put the 2 subwoofers in mono

3) gain match the subwoofers to your mains

4) put the speakers at -4 dBFs and use the miniDSP for volume control

5) Run Dirac with the Harman target curve.

 

[McFly]

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.

Maybe so, but myself and others at minidsp forum have reported clipping / heavy distortion with shd playing above -10db with dirac enabled. Since its one button on the remote i was able to prove it by simply turning off dirac, poof! Distortion gone. It was bass distortion, well before the limit of what i knew my.speakers and amp were capable of. They may have fixed this this was a year ago..

 

[abdo123]

Maybe so, but myself and others at minidsp forum have reported clipping / heavy distortion with shd playing above -10db with dirac enabled. Since its one button on the remote i was able to prove it by simply turning off dirac, poof! Distortion gone. It was bass distortion, well before the limit of what i knew my.speakers and amp were capable of. They may have fixed this this was a year ago..

oh I didn’t know that, but i do know that there is no headroom for regular filters.

Now you’re going to make me check

 

[abdo123]

Maybe so, but myself and others at minidsp forum have reported clipping / heavy distortion with shd playing above -10db with dirac enabled. Since its one button on the remote i was able to prove it by simply turning off dirac, poof! Distortion gone. It was bass distortion, well before the limit of what i knew my.speakers and amp were capable of. They may have fixed this this was a year ago..

Oh my god i feel ridicoulus for assuming something would be intuitive without me actually checking for it.

Dirac does not add any headroom and expects you to use the Dirac enabled device for volume control.

there is obvious clipping going on in my system and i didn't even notice

 

[abdo123]

@SadMonster

this shouldn't effect you if you're using the MiniDSP for volume control. which you should anyway if you're using it to integrate subwoofers.

 

[SadMonster]

Wait so should I stick with -10db on my minidsp? O_O

 

[abdo123]

Wait so should I stick with -10db on my minidsp? O_O

Use the highest gain settings on your powered speakers and subwoofers (while still being gain matched) and use the MiniDSP for volume control.

Otherwise you have to measure exactly the amount of boost DIRAC is applying and add negative gain as necessary.

 

[Frank Dernie]

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

???????
That would require 100x the power to fulfil, so is way more than I would consider even trying.
3dB for a dip may be worth a try, and even that might not work well if it is due to being very close to an anti-node in an excited room mode.

 

[abdo123]

???????
That would require 100x the power to fulfil, so is way more than I would consider even trying.
3dB for a dip may be worth a try, and even that might not work well if it is due to being very close to an anti-node in an excited room mode.

my peak listening volume if i get really frisky is 90dB, my speaker's sensitivity is 86 dB at 1m/2.87V and i listen at less than 4 meters distance.

40W is all I need theoretically, without even accounting for things like room gain, and my usual peak listening volume is more like 85 dB to be honest.

these things are relative to each person's needs.

 

[Frank Dernie]

my peak listening volume if i get really frisky is 90dB, my speaker's sensitivity is 86 dB at 1m/2.87V and i listen at less than 4 meters distance.

40W is all I need theoretically, without even accounting for things like room gain, and my usual peak listening volume is more like 85 dB to be honest.

these things are relative to each person's needs.

Whatever.
You recommended up to 10dB boost to the OP for dips. Even if normally listening at 3 watts that peak in the correction would need 300 watts from the built in amplifier which it doesn't have, so it will clip.
If the OP enjoys loud music and is adding boost of 10dB or more to fill in dips without understanding what it means no wonder it is distortion city.

 

[McFly]

Whatever.
You recommended up to 10dB boost to the OP for dips. Even if normally listening at 3 watts that peak in the correction would need 300 watts from the built in amplifier which it doesn't have, so it will clip.
If the OP enjoys loud music and is adding boost of 10dB or more to fill in dips without understanding what it means no wonder it is distortion city.

I think it was just a combination of Dirac needing 10db headroom in his MiniDSP and input sensitivity too high (gain too low) on his monitors. Like I said earlier I got bass distortion with my MiniDSP shd in my system way before music got loud. Dirac will boost to a maximum of 10db, which is just backwards IMO it should be using a preamp to drop levels before it applies any boost - but if it did this the volume levels would vary hugely when switching Dirac on and off with the remote - which it doesn’t (allowing you to AB Dirac vs no Dirac)- which further adds proof to this hypothesis.

 

[abdo123]

Whatever.
You recommended up to 10dB boost to the OP for dips. Even if normally listening at 3 watts that peak in the correction would need 300 watts from the built in amplifier which it doesn't have, so it will clip.
If the OP enjoys loud music and is adding boost of 10dB or more to fill in dips without understanding what it means no wonder it is distortion city.

what he is experiencing is a multi-faceted problem and perhaps even a mix of both digital and analog clipping.

however once he adds headroom in the digital domain then analog clipping is very likely to stop as well, no need to over complicate things.

And now thinking about it, 10 dB is probably too high for most speakers. better stick to 6 dB max.

 

[Frank Dernie]

I think it was just a combination of Dirac needing 10db headroom in his MiniDSP and input sensitivity too high (gain too low) on his monitors. Like I said earlier I got bass distortion with my MiniDSP shd in my system way before music got loud. Dirac will boost to a maximum of 10db, which is just backwards IMO it should be using a preamp to drop levels before it applies any boost - but if it did this the volume levels would vary hugely when switching Dirac on and off with the remote - which it doesn’t (allowing you to AB Dirac vs no Dirac)- which further adds proof to this hypothesis.

what he is experiencing is a multi-faceted problem and perhaps even a mix of both digital and analog clipping.

however once he adds headroom in the digital domain then analog clipping is very likely to stop as well, no need to over complicate things.

And now thinking about it, 10 dB is probably too high for most speakers. better stick to 6 dB max.

Yes but if, say, an 86dB/watt speaker has a 10dB dip in its in room FR and the software corrects for this the speaker will need the same power to achieve the corrected FR as a 76dB/watt speaker at that frequency would if it did not need compensation, which will be a lot, even if it can take it.
I know the correction has to reduce level before manipulation in order to avoid clipping the digital system but the analogue amp having to supply the power to achieve a correction of 10dB really is 100x the power and it is very likely not to be technically achievable, either because the speaker can't take that much or the amp can't supply it.
It may be able to cope at very low levels.

I suppose that is so why many advise not to try to correct dips.