# Flat Frequency Response vs Bass Decay



## Phillips (Aug 12, 2011)

Any thoughts on this topic?

Which is more important?


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## JohnM (Apr 11, 2006)

At low frequencies (below 100Hz) we have very limited ability to perceive slow decay in the absence of a peak, but can more easily detect a peak. The two ordinarily go hand in hand of course, but arguably improving the flatness has greater perceived impact in the region below 100Hz than improving the decay. This paper is one of relatively few that have looked at this issue at low frequencies: Perception of low frequency decay.


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## Phillips (Aug 12, 2011)

JohnM said:


> At low frequencies (below 100Hz) we have very limited ability to perceive slow decay in the absence of a peak, but can more easily detect a peak. The two ordinarily go hand in hand of course, but arguably improving the flatness has greater perceived impact in the region below 100Hz than improving the decay. This paper is one of relatively few that have looked at this issue at low frequencies: Perception of low frequency decay.



Hi John thank you.
I normally eq so it's bit of a compromise, not necessary flat.

Do you mean that the *human ear *can't perceive slow decay...............?

Is it best to eq the sub then speakers and sub (combined)?

Thank you


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## JohnM (Apr 11, 2006)

Phillips said:


> Do you mean that the *human ear *can't perceive slow decay...............?


Do we have another kind? 



> Is it best to eq the sub then speakers and sub (combined)?


Depends what the system is used for and what the EQ configuration is. If mostly used for movies then LFE is sub only so mains don't come into it. If the sub's main use is handling redirected bass from the fronts (e.g. if mostly music) then worth EQ'ing for the best combined response, bearing in mind the EQ filtering is often only available in the sub path.


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## Phillips (Aug 12, 2011)

JohnM said:


> Do we have another kind?
> 
> Depends what the system is used for and what the EQ configuration is. If mostly used for movies then LFE is sub only so mains don't come into it. If the sub's main use is handling redirected bass from the fronts (e.g. if mostly music) then worth EQ'ing for the best combined response, bearing in mind the EQ filtering is often only available in the sub path.



Thanks John, 

My uses are:

95% 2 Channel music
3% Multi Channel music
2% Movies

My subs are Velodyne DD12 + DD15

I was thinking of using the DD12 as the LFE & the DD15 natural roll of from the main speakers (bit like a REL)?


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## jmschnur (May 31, 2011)

It is interesting to play with the sub distance to decrease mode effects esp in the cross over region when using subs combined with fronts for stereo listening.

The REW system can lead to optimization on this regard. I have it found this helps with bass guitar esp in jazz. Of course room treatment is very import prior to to this.


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## Phillips (Aug 12, 2011)

jmschnur said:


> It is interesting to play with the sub distance to decrease mode effects esp in the cross over region when using subs combined with fronts for stereo listening.
> 
> The REW system can lead to optimization on this regard. I have it found this helps with bass guitar esp in jazz. Of course room treatment is very import prior to to this.



Thanks for that.

The crossover region is good, seems to be from about 50hz down. 

Would the distance feature in the Receiver address this?

Does REW have a feature for distance?

Do you reccomend high crossover for music only. Movies come well down the list.


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## jmschnur (May 31, 2011)

Most AVRs have distance settings. After optimization (eg. Audyssey) measure system response .then measure sub only and mains only as the article referenced in this thread has shown. If there is a mismatch try changing the distance of the sub to improve integration .

Other ways to improve system is to find place(s) for sub that minimize room mode integration . Then set your cross over above this region so that the mains do not excite the modes and since you have placed the sub (s) properly neither does the sub (s)'

REW can be used to measure the responses of the system and each individual component as you optimize.


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## Phillips (Aug 12, 2011)

jmschnur said:


> Most AVRs have distance settings. After optimization (eg. Audyssey) measure system response .then measure sub only and mains only as the article referenced in this thread has shown. If there is a mismatch try changing the distance of the sub to improve integration .
> 
> Other ways to improve system is to find place(s) for sub that minimize room mode integration . Then set your cross over above this region so that the mains do not excite the modes and since you have placed the sub (s) properly neither does the sub (s)'
> 
> REW can be used to measure the responses of the system and each individual component as you optimize.


Thank you

What crossover range do you recomend for a music, mainly 2 channel system?


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## jmschnur (May 31, 2011)

Phillips said:


> Thank you
> 
> What crossover range do you recomend for a music, mainly 2 channel system?


Really depends on the speakers, sub, and room.

If your speakers are full range and your room has no modes then no sub is a good choice. With a very good sub and a limited range set of mains 80 hz will be fine.

I have 2 very good subs and the Martin Logan Montis with some hard to tame modes. I use 70 hz after some careful placement of my subs to minimize the interaction with my low frequency modes.

I also did the distance trick after all was done to good effect.

80 hz seems to be reasonable in a large number of systems.


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## Phillips (Aug 12, 2011)

jmschnur said:


> Really depends on the speakers, sub, and room.
> 
> If your speakers are full range and your room has no modes then no sub is a good choice. With a very good sub and a limited range set of mains 80 hz will be fine.
> 
> ...



I have 2 subs Velodyne DD12 & DD15, how would you recomend they be setup/try, due to different size drivers?

They are run as mono, due to mainly the driver size difference.

The main speakers extend to 35hz.

Thank you

What do you think of the idea of using the DD15 for extension of the main speakers and the DD12 for LFE?


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## jmschnur (May 31, 2011)

Phillips said:


> I have 2 subs Velodyne DD12 & DD15, how would you recomend they be setup/try, due to different size drivers?
> 
> They are run as mono, due to mainly the driver size difference.
> 
> ...


How do you set up the sub integration and placement?

What is your pre/pro /receiver?


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## Phillips (Aug 12, 2011)

jmschnur said:


> How do you set up the sub integration and placement?
> 
> What is your pre/pro /receiver?



Currently:
Subs are inside the main speakers (very little option)
Measure with REW with all options (from full range - bass management 40,60,80,90,100,110,120,160,200) to find the least room modal problems.
Measure with REW with all included subs (DD12 & DD15) + mains
Eq with mains included.

Yamaha Z9


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## jmschnur (May 31, 2011)

Phillips said:


> Currently:
> Subs are inside the main speakers (very little option)
> Measure with REW with all options (from full range - bass management 40,60,80,90,100,110,120,160,200) to find the least room modal problems.
> Measure with REW with all included subs (DD12 & DD15) + mains
> ...


Can you equalize the summed subs with the Yamaha ? If you used one for the your mains and one for your .1 HT theater how would you calibrate the system?

I am inclined to suggest your smaller sub be linked to your mains and the larger to the HT .1 for movies but usually two subs help smooth out the bass in a room. Music does not need very low bass but the effects for movies do.

Can you set different xovers for the subs used this way? How does your system sound for music with no subs.

Then try the subs linked with xover at 80 and decide which is better .


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## Phillips (Aug 12, 2011)

jmschnur said:


> Can you equalize the summed subs with the Yamaha ?
> If you used one for the your mains and one for your .1 HT theater how would you calibrate the system?
> 
> I am inclined to suggest your smaller sub be linked to your mains and the larger to the HT .1 for movies but usually two subs help smooth out the bass in a room. Music does not need very low bass but the effects for movies do.
> ...



Yes i can eq with the Yamaha, but i don't like what it does, so i use the Velodyne 8 band Parametric EQ (per sub).
I would use the EQ in the Velodyne for the LFE, then intergrate the sub with mains natural roll off. Set the Yamaha to Large for the main speakers and the LFE to Sub. The Velodynes have speaker inputs as well as RCA. The Velodynes have alot settings/adjustments for optimizing.

Yeah i could try either sub for LFE/Mains. You are right with dual subs smoothing.

Yes i can set different Xovers for the subs on the mains sub + disable the other one and set the Yamaha crossover.
The mains on there own don't sound to bad, but have a room mode at 36hz which the Yamaha cannot deal with. 
Yeah it's a matter of playing with the sub. Having all the adjustments and EQ, this has more power to adjust/EQ in the Velodynes.

Thanks


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## jmschnur (May 31, 2011)

Phillips said:


> Yes i can eq with the Yamaha, but i don't like what it does, so i use the Velodyne 8 band Parametric EQ (per sub).
> I would use the EQ in the Velodyne for the LFE, then intergrate the sub with mains natural roll off. Set the Yamaha to Large for the main speakers and the LFE to Sub. The Velodynes have speaker inputs as well as RCA. The Velodynes have alot settings/adjustments for optimizing.
> 
> Yeah i could try either sub for LFE/Mains. You are right with dual subs smoothing.
> ...


Probably better to roll off the mains above the 36. Xover at 50 may sound better. Then use your small sub with the mains, Can you put your small sub on side wall to see if that sounds better integrated with the main only at 50 hz for music.


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## Phillips (Aug 12, 2011)

jmschnur said:


> Probably better to roll off the mains above the 36. Xover at 50 may sound better. Then use your small sub with the mains, Can you put your small sub on side wall to see if that sounds better integrated with the main only at 50 hz for music.


Thank you

I have tried the smaller sub with the mains, but i prefer the bigger one on music. Looking on the website people tend to prefer the DD15 for music over the DD12 & DD18.

No harm in changing around though.

The speakers roll off pretty steep @ 32hz, you suggest 50hz would that work, or would that able me to eq/adjust that room mode?

Movies aren't a high prioity in my eye, more music and multi channel music.

Thanks again.


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