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Newb questions about MiniDSP SHD with Dirac Live to improve the sound in my living room as I am considering getting one. One speaker is kind of stuck in the corner so I would like to even out the bass response , plus extract any additional bass from the mini floorstanders that I am using as my subwoofer is currently out of the system due to space constraints.

 

1. Does it require a substantially powerful power amp to boost the bass frequencies, or does the strain happen in the pre amp side of the path? I currently have a Purifi which is 425w at 4ohms. 

 

2. Is there a limit on how many dB's you can or should boost the bass signal ie. +10 dB? What determines this and can a more powerful power amp improve this? ie. Hypex NC1200, or is it more about the speaker or pre amp section?

 

3. Do speaker ports play any role? Since the ports are tuned to a frequency can they be boosted? Would a sealed speaker be a better candidate since they actually go lower but suffer from SPL output which the DSP makes up for? I noticed some actives are sealed designs.

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10 hours ago, Midget said:

Newb questions about MiniDSP SHD with Dirac Live to improve the sound in my living room as I am considering getting one. One speaker is kind of stuck in the corner so I would like to even out the bass response , plus extract any additional bass from the mini floorstanders that I am using as my subwoofer is currently out of the system due to space constraints.

The MiniDSP SHD with Dirac Live is not the silver bullet that you are looking for. 

 

Uneven bass is due to the ROOM and how your speakers interact with the room.  If you have a bass trough in the room, it cannot be corrected by boosting bass!  If you try boosting the bass, it will lead to distortion and may damage your equipment.  Please forget about boosting bass with more power amps, extracting additional bass from the mini floor standers, playing around with speaker ports.

 

Getting the Anti Mode 2.0 will help reduce some of the problems.  Some of the reviews do explain in more detail how it works.

http://www.dspeaker.com/en/products/20-dual-core.shtml

 

Yes, you have space restrictions, but adding a small sub such as the SVS 3000 Micro will go a long way to getting even bass. 

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So DSP can not increase the natural roll off of a speaker? I thought that was one of the things that separated non active and active versions of the same speaker design?

 

Where does the distortion come from? The preamp that is adding the boost, the power amp, or the speaker driver?

 

In regards to the uneven bass, I thought the speaker in the corner might have too much bass. I already have the port plugged but thought there might be a way to reduce bass using DSP to make it more even.

 

Thanks for the link Snoop, I'll look into it!

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I think you are misunderstanding how bass interacts with the room.  The troughs are caused by sound waves interacting with the walls, ceilings, and cancelling each other in different parts of the room.  Boosting a bass signal will not remove the interaction.  If you go down the path of over boosting a bass signal, you may damage your amp or speakers.

 

Please have a read of these reviews; it explains things better than I can.

https://www.theabsolutesound.com/articles/dspeaker-anti-mode-20-dualcore-digital-signal-processor

https://www.avforums.com/reviews/dspeaker-anti-mode-2-0-dual-core-review.355

The second review also covers a bit about waterfall diagrams, which cover why bass can get muddied by long decay times.

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Thanks @Snoopy8

 

I have read both articles and it sounds like I was on the right track. It did fill in the blanks and also confirmed some of my preconceived thoughts. I'll summarise to see if I understood it correctly and post up a few follow up questions that I am still curious about.

 

  • Boosting bass frequencies puts stress on the both the power amp and the speaker
  • Evening out the response is more safely handled by decreasing the spikes
  • Increasing big divots can not be corrected by boosting as it is more about room interactions and speaker placement
  • Repositioning a speaker is one solution to fixing these big divots in frequency response
  • Fixing natural roll off of speakers can be corrected for by increasing the lower frequencies or lowering the higher frequencies
  • This is what is called a 'house curve' in which the bass is attempted to be corrected to be flat and the overall response tilted downwards
  • DSP works best for 300Hz and below as you are mostly correcting for the room. Correcting too much at higher frequencies can result in a negative effect

A few follow ups:

 

1. Power amp choice - Am I correct that if any boosting is done, instead of lowering everything to create the desired curve, that class D would be a good choice due to its lower thermal properties? Again, does overall power give more headroom?

 

2. Only reducing - Am I correct that you could create the desired response by only using reductions. The tradeoff would be that the overall output of the system might be reduced but neither the amp or speaker would be driven beyond its capabilities?

 

 3. Using one speaker to correct the other - My understanding is that the overall bass response is an accumulated effect from both speakers. The Dual Core seems to be limited by applying the same adjustments to both speakers. If one speaker had a null but the other didn't, would a seperate adjustment to each not allow the speaker that doesn't have a null to correct for the one that does? (To a certain degree of course within the limits of the boost and overall reductions)

 

4. Volume dependant correction - Active speakers tend to lose their DSP correction when they get closer to their limits. I take it this is to protect both the amp and the speaker. It doesn't look like the Dual Core does this, but does the MiniDSP SHD? I would also like the functionality of even more bass boost at very low volumes akin to 'Loudness' but only in the bass region. If it's not automatic then maybe three presets is the answer.

 

5. Recommended limit of boosting - The Dual Core appears to have pre sets for how much it corrects by boosting, "normal/typical" and "maximum". How many dB is maximum do you think? I take it this is what they believe is the most you can do safely.

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I do not boost any frequencies and solve the bass problems in my living room with 2 subs and a DSP.

 

Yes, you have limited space, but you can improve things by changing the speaker positions,  by as little as 0.5m, and also your listening position.  Bass is uneven in the room, because of the room. No amount of boosting of existing sources will fix bass problems. 

 

Room treatment and adding more subs, with DSP are potential solutions.  The key is to get even bass, not loud bass.

 

You will need to find someone else to discuss boosting the bass...

 

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46 minutes ago, Snoopy8 said:

Room treatment and adding more subs, with DSP are potential solutions.  The key is to get even bass, not loud bass.

 

You will need to find someone else to discuss boosting the bass...

 

 

No worries Snoop I will wait to see if anyone else has advice, however the articles you referenced clearly discuss bass boosting and the inadequacies of typical room treatment for these lower frequencies. I am just trying to understand what options I have if the other methods for correction are not an option, and how to safely do it. (I have a sub with built in DSP room correction but I do not want to use it due to space constraints). 

 

Of course my goal is to get even bass as previously stated, but also to correct for bass roll off which dips below that even frequency response target we all would like to achieve. The only way to do it is for the frequencies below this target to get louder, which is different to "loud bass" which I would describe as a mismatch in frequency response heavily favouring the lower regions. 

 

I appreciate your time though, thank you.

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I agree that room treatment is not enough by itself and adding subs after room treatment will give better results. It is OK to do a minor amount of boosting, but not to the extent of that you are considering. Yes, the bass has to be louder to compensate for the troughs, but you use the bass from additional sources like subs , not via boosting the bass from the mains.  You have missed the point that boosting the bass frequency on the mains will result in the same bass troughs, maybe even worse.  The bass troughs are due to speaker room interactions.

 

FYI, this is how I do it, much harder to implement than Dirac Live, Anti-Mode etc... but worked for me.

https://www.stereo.net.au/forums/topic/242166-using-multi-subs-mso-to-get-even-bass-in-room-across-sitting-positions/

 

Best wishes in your music journey...

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I am no expert but Ive managed to get results which are pleasing to me and anyone else that hears my system via a NAD C658 Dirac and twin Rel Subs.

 

My current curve is attached and I boost the bass and mids but close the curtains at 150hz so nothing above is touched.

 

The boosting I have done does not even begin to sound distorted or cause my components any stress, I haven't boosted to fix any null issues which I think the dual subs do anyway, but it just sounds the way I like it, full and lush.

 

I could not live without having subs in my music now and Dirac just makes it so easy to get sounding great once you have some basic knowledge.

 

But when it comes to boosting, it's each to thier own I guess. I know there are people who don't do it, I even used to try and be a "purist" and have no bass or treble controls in my system because "it's the way a system should be". I then got the Nad and Dirac and threw out any of those previous misconceptions, and when I did I managed to have my system sounding the best it ever has, and when it sounds good to me, the rest doesn't matter!

 

12949181_ScreenShot2021-05-03at2_57_51pm.thumb.png.38772fc31e333d44345991f8b1011cba.png

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22 hours ago, Snoopy8 said:

I do not boost any frequencies and solve the bass problems in my living room with 2 subs and a DSP.

 

Well this is an interesting one.

While MSO can be configured and is by default to not apply gain by PEQ's it can increase the overall gain of the subs if a Gain Block is added and is configured to allow positive gain.

So this is the same as boosting a subwoofers output for all frequencies.

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5 minutes ago, Satanica said:

 

Well this is an interesting one.

While MSO can be configured and is by default to not apply gain by PEQ's it can increase the overall gain of the subs if a Gain Block is added and is configured to allow positive gain.

So this is the same as boosting a subwoofers output for all frequencies.

Let me clarify. I do not boost the bass frequencies in the main speakers, which is what OP is trying to do.

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Posted (edited)
21 hours ago, Midget said:

 

No worries Snoop I will wait to see if anyone else has advice, however the articles you referenced clearly discuss bass boosting and the inadequacies of typical room treatment for these lower frequencies. I am just trying to understand what options I have if the other methods for correction are not an option, and how to safely do it. (I have a sub with built in DSP room correction but I do not want to use it due to space constraints).

 

I utilise all four of the profiles on my miniDSP SHD Studio and three of them apply bass boost to both my main speakers and sub-woofers.

The profile with the largest bass boost boosts by about +6dB.

I use two large sub-woofers in my system for low bass which are flat to 16Hz and high-pass my main speakers at 80Hz.

The default Dirac Live profile has bass boost.

 

Also I use Dirac Live full frequency and like it.

 

The safe way to do it is to not try and bass boost where your speakers and sub-woofers don't have much output.

So if you look at how @Hi-Fi Whipped is using Dirac Live is a good example because the EQ roughly follows the output of the speakers and sub-woofers.

In this example this is not really bass boosting but bass evening\smoothing.

The speakers start droppping off at 50Hz and the subwoofers at about 32Hz.

Edited by Satanica
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On 02/05/2021 at 11:05 PM, Midget said:

So DSP can not increase the natural roll off of a speaker?

 

Yes, it can.

 

On 02/05/2021 at 11:05 PM, Midget said:

Where does the distortion come from?

 

If you keep the overall SPL the same... and increase the bass from a driver..... you increase the cone movement... which increases distortion.

 

How much?   That depends.   It can be substantial.

 

If you monitor the maximum movement of the woofer (and know what the limit is) ... and are careful with the volume dial ... then you won't damage anything.

 

 

On 02/05/2021 at 11:05 PM, Midget said:

In regards to the uneven bass, I thought the speaker in the corner might have too much bass. I already have the port plugged but thought there might be a way to reduce bass using DSP to make it more even.

 

Yes, EQ can set the bass to anything you want it to ... more/less, etc.

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My system has 2-way passive sealed enclosure main speakers with an a single subwoofer, all fed by MiniDSP.  Recently I have been experiment with extending the bass response of the main speakers with DSP, exactly as Dave is describing above.  A smart (understatement) guy called Linkwitz invented a transform that you can use to calculate all the needed parameters.  It only works with sealed speakers,  mind.

Doing this gives three rather than one source for lower bass which has got  to be good.  The big "buts" are clearly outlined above by Dave.  I'm only using a "touch" of LT due to lack of power and speaker Xmax but the results seem to be worth it.  I've probably extended the speakers bass from 80Hz to about 60Hz.

Obviously you also need to mindful about the problems of applying boost to frequencies that are not "boostable" due to the room.  

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23 hours ago, Snoopy8 said:

I do not boost any frequencies and solve the bass problems in my living room with 2 subs and a DSP.

 

Yes, you have limited space, but you can improve things by changing the speaker positions,  by as little as 0.5m, and also your listening position.  Bass is uneven in the room, because of the room. No amount of boosting of existing sources will fix bass problems. 

 

Room treatment and adding more subs, with DSP are potential solutions.  The key is to get even bass, not loud bass.

 

You will need to find someone else to discuss boosting the bass...

 

 

 @Midgetcan i support these points as this is absolutely crucial... I want to call out that i am seeing some scary boosting going on with arcam AVRs with dirac and as default and this can end in tears. have seen one fellow blow up his denon not knowing why ! then switching to arcam and it is of course shutting down with warnings... turns out its wanting to do some scary boosts...

 

the article from JLaudio below is a very good one... and highlights so well as per snoops note... to cut ... dont boost ...

https://jlaudio.zendesk.com/hc/en-us/articles/217201737-Doubling-Power-vs-Doubling-Output

 

was it says an increase in 3db doubles the power requirement, + 6 db quadruples amplifier power requirement... start doing +10db boosts and you need 10x the power...

 

very few power amps have the kind of power reserves to sustain this sort of thing, let alone not start getting strained.... and especially if dirac without your knowing is doing some +10db boosts ! arcam AVRs are decent but no ways will they even sustain that sort of demands ! AVRs are compromise enough but be few and far between be multichannel power amps that will clean support that sort of thing either. 

 

far better to fix room issues with the room and locations used wihthin the room... of main listening position... after all if decide to sit in the middle of the room where for mosts its going to be a null no matter of boosting is going to solve this .... better to sit 2/3rd depth using rule of thirds...alternatively sit back to wall and you get huge gain and all can do is kill the bass to point can end up sounding lifeless and with nothing in reserve... again easily fixed... same with speakers and subwoofer locations much easier to optimise these than try to do band aids with EQ ! 

 

it is a double edge sword too ...eg audyssey by definition doesnt boost it cuts... but then you have situation where folk find inadequate and keep cranking the volume to compensate.... similarly with dirac... it can boost but if trying to fix a null it wont and folk will crank again here and its heading for a quick death and shut down to prevent :)

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Dumb question but can Dirac  tell the difference between minimum phase and non-minimum phase dips in room response?   And can you select a maximum boost level?  So that it will never try to apply, say, 20 dB of boost to a 25Hz non-minimum phase null?  If would assume yes and yes but that's just a guess.

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Posted (edited)
On 03/05/2021 at 12:08 PM, Snoopy8 said:

The key is to get even bass, not loud bass.

 

It is well known that bass frequencies vary (a lot) between recordings.

And it is also quite well known and dare I say accepted that a flat frequency response can sound unsatisfying regarding bass frequencies with many recordings.

So, I don't know how anyone can one argue that it isn't somewhat flawed to only have one target curve for ultimate music satisfaction.

For some recordings I think it can be argued that loud bass (boosted\shaped) will subjectively sound better than even (flat) bass.

Presumably miniDSP and Dirac Live know this which is why they have facilitated the ability to have multiple target curves at the press of a button.

 

 

On 03/05/2021 at 12:08 PM, Snoopy8 said:

You will need to find someone else to discuss boosting the bass...

 

I think some of the discussion in this thread is getting a bit confusing regarding applying EQ gains (boosting).

Although the same action is applied there is seemingly two types.

EQ gains (boosts) to smooth-en a response and EQ gains (boosts) needed to shape to a desired response.

Dirac Live makes it easy to combine the two because one only needs to present the target curve rather than decide what action(s) need to be applied to try and achieve it.

 

 

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7 minutes ago, RoHo said:

And can you select a maximum boost level?  So that it will never try to apply, say, 20 dB of boost to a 25Hz non-minimum phase null?  If would assume yes and yes but that's just a guess.

 

No I don't think you can adjust the boost level.

 

This is a not so recent article but might still be relevant.

 

https://www.audioholics.com/room-acoustics/dirac-room-correction-interview

 

Audioholics: What is the maximum boost / cut your room correction products will apply? Is it possible for users to set a limit in this respect (i.e. no more than 3dB of boost)?

Mathias Johansson: Normally, Dirac Live does not allow you to boost more than 10 dB. You can lower this by adjusting the target curve. However, narrow dips (nulls) are never compensated, as they are always position dependent in real acoustic spaces.

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1 hour ago, RoHo said:

My system has 2-way passive sealed enclosure main speakers with an a single subwoofer, all fed by MiniDSP.  Recently I have been experiment with extending the bass response of the main speakers with DSP, exactly as Dave is describing above.  A smart (understatement) guy called Linkwitz invented a transform that you can use to calculate all the needed parameters.  It only works with sealed speakers,  mind.

 

 

You can figure out a transform starting with any response.... but it gets complex.... but these days, nobody has to calculate anything.   "LT"  comes from a time when calculators were fancy, and graphing calculators we stuff of the "space program".

 

1 hour ago, RoHo said:

Doing this gives three rather than one source for lower bass which has got  to be good.

 

As long as there's not too much distortion.

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33 minutes ago, RoHo said:

Dumb question but can Dirac  tell the difference between minimum phase and non-minimum phase dips in room response?   And can you select a maximum boost level?  So that it will never try to apply, say, 20 dB of boost to a 25Hz non-minimum phase null?  If would assume yes and yes but that's just a guess.

 

The concept of phase becomes pretty much useless at these frequencies, aside from how it can relate to level vs location.

 

Measure in all the seat you care about and then let it do it's thing.

 

If you want to help DL .... put some effort in the placement, and EQ of individal bass sources, so that their combined response is the flattest possible.

 

Another approach is to use the Dirac Live Bass Control addon ..... which exploits the subwoofer (and speakers if they play low enough) phases to try to address modal issues.    It's basically like "MSO" (software) but extending the approach to fine control over the phase of each bass source (as opposed to just the delay).

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6 minutes ago, davewantsmoore said:

Another approach is to use the Dirac Live Bass Control addon ..... which exploits the subwoofer (and speakers if they play low enough) phases to try to address modal issues.    It's basically like "MSO" (software) but extending the approach to fine control over the phase of each bass source (as opposed to just the delay).

 

Unfortunately it is not currently supported by miniDSP.

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What's missing here is some specific information. There is a lot of generally true advice that turns out not to be useful in many specific cases. Sometimes in a small room, just a pair of speakers is enough to get good bass. Even though one or two subs usually give a big improvement in the right positions.

 

But as a general rule, there are two things that are best done before you start calibrating. Room treatment and figuring out the bare bones bass solution - where the bass makers will go, if you will use subs, how many etc. If you load the room correctly, you won't be trying to do the impossible with EQ.

 

Applying EQ boost is VERY EXPENSIVE. If you don't first get woofers or subs in optimal positions, you may be trying to fix this with 15 dB boost or more. This is like turning a 1kw amp into 25 watts!

 

You can extend the response of any speaker with EQ. With a sealed speaker, this is limited by excursion, distortion and power handling (both driver and amp). With ported speakers, boost should be limited to the range above tuning. Below tuning the excursion and distortion rise dramatically without any worthwhile increase in output.

 

The two most common mistakes people make regarding subs are:

1. Ruling them out completely

2. Deciding two are necessary without testing

 

People often rule them out because of space. Often with just a little creative thinking, you can find a workable position. Very often it will solve problems EQ can't. Sometimes if you can put the smallest of subs in a very strategic position, it can be a game changer. Very often it works out that a position that measures beautifully, also works out aesthetically, even when the first response to a sub was "NO it can't be done!" .... I do take that as a challenge!

 

Why is two subs a mistake? I've seen many people get a worse result with two or even five subs, compared to just one in a non crazy position. 5 subs is a solution almost nobody needs. It's usually best to go with the simplest solution that works.

 

 

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8 minutes ago, Paul Spencer said:

2. Deciding two are necessary without testing

...

Why is two subs a mistake? I've seen many people get a worse result with two or even five subs

 

Definitely....

 

I'd reiterate what you said above, by pointing out that this is mostly an example of how critical good positioning of a subwoofer is..... to the point that two in non-optimal positions can we worse than one, or none.

 

EQ is also critical.... but without sensible positioning, it can be asking a lot.

 

Subs almost always make a huge improvement, but without proper setup ..... can give a pretty bad result.

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Thank you everyone for the additional info. This is very helpful. A few comments below:

 

11 hours ago, Satanica said:

The profile with the largest bass boost boosts by about +6dB.

 

Satanica would you say this is an advisable max? Or just what your system required?

 

11 hours ago, davewantsmoore said:

If you monitor the maximum movement of the woofer (and know what the limit is) ... and are careful with the volume dial ... then you won't damage anything.

 

Does this mean speakers with a higher power capability are better for the task? I take it they are designed to handle some heavy current and driven hard if they say they can handle 300 watts for example.

 

10 hours ago, betty boop said:

an increase in 3db doubles the power requirement, + 6 db quadruples amplifier power requirement... start doing +10db boosts and you need 10x the power...

 

very few power amps have the kind of power reserves to sustain this sort of thing, let alone not start getting strained.... and especially if dirac without your knowing is doing some +10db boosts !

 

Thanks Betty Boop your caution is noted and I will be careful with my equipment. This leads me back to one of my original questions which I am hoping someone can answer.

 

Does a more powerful amp give you more headroom for these bass boost corrections?

 

For example, my 8 watt amp has all the power I need for my listening levels without disturbing the neighbours, so can I assume my normal listening levels are not using that many watts, and that a bass boost of +9dB might only use at max 64 watts (8>16>32>64)? (With those extra watts only being drawn when those specific boosted frequencies are being played)

 

My intended amp of use will be a Purifi Class D which is 425w at 4 ohms and 450 at 2 ohm. Is this enough power for +9dB adjustments would you say, even though it might require nearly 10 times the power? (My major assumption in this premise is that we use far less watts than we think for normal listening)

 

On 03/05/2021 at 3:15 PM, Hi-Fi Whipped said:

I am no expert but Ive managed to get results which are pleasing to me and anyone else that hears my system via a NAD C658 Dirac and twin Rel Subs.

 

The boosting I have done does not even begin to sound distorted or cause my components any stress, I haven't boosted to fix any null issues which I think the dual subs do anyway, but it just sounds the way I like it, full and lush.

 

What power amp are you using Hi-Fi Whipped? Does Dirac Live have options that are volume dependant? So if you go to party like levels it automatically reduces and boosts, and at really low level listening can it automatically increase the bass on a more tilted response?

 

5 hours ago, Paul Spencer said:

You can extend the response of any speaker with EQ. With a sealed speaker, this is limited by excursion, distortion and power handling (both driver and amp). With ported speakers, boost should be limited to the range above tuning. Below tuning the excursion and distortion rise dramatically without any worthwhile increase in output.

 

Paul this sounds like you are saying extending the natural roll off of a speaker using dsp is not really applicable to ported speakers as the roll off is generally coming from the port, and that it is more applicable in a sealed speaker, provided a few requirements are met.

 

 

One last question for those who are integrating subs:

 

Do you high pass the main speakers at the roll off of the woofer, or the port? Is there any audible difference in removing the frequency range that falls within the ports area of coverage and letting the subwoofer handle this?

 

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8 hours ago, Midget said:

 

What power amp are you using Hi-Fi Whipped? Does Dirac Live have options that are volume dependant? So if you go to party like levels it automatically reduces and boosts, and at really low level listening can it automatically increase the bass on a more tilted response?

I’m using an Elektra TheatreHD, before that a Rotel1582mk2 and before that a CXR200 Cambridge AVR.

 

On the Nad you can have 5 different target curves to suit needs but they are passive not active curves (if that makes sense) so you need to manually switch them but it’s easy.

 

The Nad Dirac target curve they provide on their website for people that like some more bass compared to the flat Dirac curve tops out at around +6.5 at 30hz which is also where mine tops out, I effectively modelled mine off that, so never thought there was an issue and be it right or wrong probably still don’t.

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Posted (edited)
11 hours ago, Midget said:

Satanica would you say this is an advisable max? Or just what your system required?

 

It really depends on what your system comprises of and what its capabilities are.

I experimented with up to +10dB boost but I found that anything greater than +6dB was too much.
Note I am also using software based Loudness compensation (JRiver Media Center).

At the moment I'm only using the +6dB profile for the most bass lean recordings and I've attached a screen shot of what it looks like.

 

image.png


I've done a fair bit of experimenting and have found that too much boosting in the midbass about 80Hz to 150Hz makes what I hear from my system sound "slow".
So as you can see there is only a relatively small boost there.

 

Also, with Dirac Live curves you can choose to cut instead of boost or do a bit of both.
Although I don't use this curve I've attached a screen-shot illustrating.

With the one below there is only a small bass boost and a more significant cut at higher frequencies.

Of course this will limit maximum SPL but it provides a safe(r) way of doing a target curve.

 

image.png

 

 

 

 

 

 

Edited by Satanica
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Posted (edited)
17 hours ago, Paul Spencer said:

Why is two subs a mistake? I've seen many people get a worse result with two or even five subs, compared to just one in a non crazy position. 5 subs is a solution almost nobody needs. It's usually best to go with the simplest solution that works.

 

I think one subwoofer is not absolutely optimal.


Although I think very good results can be achieved with one subwoofer if the main speakers significantly contribute to bass frequencies making them subwoofers themselves ...

 

AND\OR

 

... using one subwoofer at a low crossover point say 50Hz or lower where the position in the room of the one subwoofer doesn't make much if any real difference.

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11 hours ago, Midget said:

Does this mean speakers with a higher power capability are better for the task? I take it they are designed to handle some heavy current and driven hard if they say they can handle 300 watts for example.

 

 

This means you need enought cone movement (with low enough distortion from both the speaker and amplifier) to reach your SPL goals....

 

More than that is not better.... although "low enough" distortion varies between people (its subjective).

 

"More" isn't better.    If you go off an "get 500w" and you only need 100 ..... then that doesn't inherently do anything good.

 

 

11 hours ago, Midget said:

caution is noted and I will be careful with my equipment.

 

Let Dirac do it's thing..... boost is fine, if used appropriately.

 

Your job is to be guardina of the volume knob...... if there is "too much boost" you will not be able to attain a high enough system volume before distortion (and/or too much cone movement) sets in.

 

ie. you'll get "lots of bass" but at an overall system volume which isn't loud enough.

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1 minute ago, Satanica said:

I think one subwoofer is not absolutely optimal.

 

It's impossible to generalise.... except to say if you place a subwoofer badly it can be "more trouble than it's worth" (ie.  you'll get a worse, or at least not  much better, result)

 

.... and the "odds" of placing (one of them) badly go up the more you have.

 

 

Of course, if you do "everything right", then (generally) more is better (as people usually need more dispalcement to get low distortion low bass, unless they're already well endowed in the subwoofer department).

 

It's more about what you do with it.... as opposed to "what you have"..... but it's easy to forget than when caught up with "how big is it", "how much did it cost", "how nice does it look" ... etc.   where as sound waves are invisible.

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41 minutes ago, davewantsmoore said:

Let Dirac do it's thing..... boost is fine, if used appropriately.

 

Your job is to be guardina of the volume knob...... if there is "too much boost" you will not be able to attain a high enough system volume before distortion (and/or too much cone movement) sets in.

 

 

55 minutes ago, Satanica said:

Also, with Dirac Live curves you can choose to cut instead of boost or do a bit of both.

...

Of course this will limit maximum SPL but it provides a safe(r) way of doing a target curve.

 

From both your responses it sounds like the safest thing for me to do is to try doing the majority of smoothing with cutting and doing minimal boosting as a starting point. I could lower the overall target curve to achieve this and still maintain a tilted frequency response that favours a little bass tilt. However, this would affect the overall SPL ability of the whole system, but I could see if the max volumes achieved is good enough for my needs. If not, I could bring the overall target curve a bit higher and try again knowing that each time I do this I am boosting more of the bass frequencies and cutting less.

 

53 minutes ago, davewantsmoore said:

"More" isn't better.    If you go off an "get 500w" and you only need 100 ..... then that doesn't inherently do anything good.

 

Got ya, so once a certain threshold is met anything past that doesn't hold an more advantage over the other.

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1 hour ago, Satanica said:

I think one subwoofer is not absolutely optimal.

 

As Dave pointed out, this is not a good place to generalise.  When I test rooms for sub positions, about half of them only need one sub to get one seat to perform well. In these rooms, adding more subs won't provide a worthwhile benefit in smoothing the response. Keeping in mind that optimising more seats is quite different.

 

My room is in this group. I have just one sub and a response of +/- 0.5 dB across the sub passband with very little variation across the 3 main seats. I'd have built 8 subs if necessary. Knowing that I only needed one, I built a horn sub and made sure it had loads of headroom.

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20 minutes ago, Paul Spencer said:

 

As Dave pointed out, this is not a good place to generalise.  When I test rooms for sub positions, about half of them only need one sub to get one seat to perform well. In these rooms, adding more subs won't provide a worthwhile benefit in smoothing the response. Keeping in mind that optimising more seats is quite different.

 

My room is in this group. I have just one sub and a response of +/- 0.5 dB across the sub passband with very little variation across the 3 main seats. I'd have built 8 subs if necessary. Knowing that I only needed one, I built a horn sub and made sure it had loads of headroom.

 

Fair enough, although your system is not typical. 

 

Out of interest what crossover/filters are you using with your mains?

 

What target curve(s) have you equalised to? 

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On 04/05/2021 at 5:42 PM, Paul Spencer said:

But as a general rule, there are two things that are best done before you start calibrating. Room treatment and figuring out the bare bones bass solution

Hi Paul,

 

I agree room treatment is important, and I have quite a bit of large/deep porous absorption (Acoustisorb 3) in my room which cleans up >150Hz nicely, but its effectiveness is dropping <150Hz...and more specialist treatment would be needed to work below that...and typically the size would get beyond acceptable WAF metrics :(

 

Fortunately my leaky room just lets all the low bass out...but in the context of this thread, which has headed down a path of  "achieving good 'in room' bass/sub bass", were you referring to room treatment that operates at sub frequencies?

 

 

Throughout your Acoustic Consultant work have you found rooms (presumably with more rigid boundaries than my room) that needed specialist "bass traps" that couldn't achieve good bass through positioning/multiple subs/EQ?

 

5 hours ago, Paul Spencer said:

I have just one sub and a response of +/- 0.5 dB across the sub passband with very little variation across the 3 main seats.

that is an amazing result 👍

 

5 hours ago, Paul Spencer said:

Knowing that I only needed one, I built a horn sub and made sure it had loads of headroom.

Are you still using your T20 tapped horn or something else now?

 

cheers,

Mike

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On 04/05/2021 at 11:29 AM, Satanica said:

The profile with the largest bass boost boosts by about +6dB.

 

19 hours ago, Midget said:

Satanica would you say this is an advisable max? Or just what your system required?

 

8 hours ago, Satanica said:

It really depends on what your system comprises of and what its capabilities are.

^this

6dB of boost may be too much for either the bass drivers (ie too much excursion) or amps (approaching/hitting clipping), or they may handle it easily, ie the drivers remain comfortably below Xmax and the amps don't come close to clipping...unfortunately it depends...

 

...good system design is required to not exceed driver/amp specs so you don't break stuff...

 

...I've managed to break plenty of stuff over the years - mostly toasted driver voice coils, but also poled drivers (exceeding their Xlim)

 

I would recommend to always be sympathetic to your gear - listen for distortion/stress, watch for large driver excursion, keep an eye on amp clip lights...and even take note of smell.

Amps working hard can have a smell - turn it down...

Drivers having a smell usually means you've overheated the voicecoil and the glues on the voicecoil have started to let go - turn down immediately...but likely you've already suffered damage.

 

I push my setup pretty hard, and back-off the volume at any signs of stress...

 

9 hours ago, davewantsmoore said:

Your job is to be guardian of the volume knob......

^this

Well managed, I can hit nightclub volumes if I want to on my setup, and occasionally I do...not often...but a sympathetic ear/eye/nose helps to mitigate the risk of gear failure, assuming you've got the design right at the start (ie driver excursion remaining comfortably under Xmax and amps remaining below clipping)

 

On 04/05/2021 at 11:49 AM, davewantsmoore said:

If you keep the overall SPL the same... and increase the bass from a driver..... you increase the cone movement... which increases distortion.

 

How much?   That depends.   It can be substantial.

 

If you monitor the maximum movement of the woofer (and know what the limit is) ... and are careful with the volume dial ... then you won't damage anything.

I agree with this, ie excursion = distortion

Better bass drivers have designs (eg copper sleeves) that help to minimise/reduce the distortion with excursion, but keeping excursion low is a good thing on any driver to keep distortion low.

Remaining below the Xmax (excursion limit) of a sub driver (actually any driver) is recommended - if you need more SPL, then you need an additional sub .

 

cheers

Mike

 

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22 hours ago, Satanica said:

 

Fair enough, although your system is not typical. 

 

Out of interest what crossover/filters are you using with your mains?

 

What target curve(s) have you equalised to? 

 

The sub operates from 20 - 60 Hz then hands over to sealed 18" bass boxes (60 - 350 Hz).

 

The system is calibrated to the "Red Spade target curve" which is similar to the Harman curve but more generous with the bass.

 

17 hours ago, almikel said:

Hi Paul,

 

I agree room treatment is important, and I have quite a bit of large/deep porous absorption (Acoustisorb 3) in my room which cleans up >150Hz nicely, but its effectiveness is dropping <150Hz...and more specialist treatment would be needed to work below that...and typically the size would get beyond acceptable WAF metrics :(

 

Fortunately my leaky room just lets all the low bass out...but in the context of this thread, which has headed down a path of  "achieving good 'in room' bass/sub bass", were you referring to room treatment that operates at sub frequencies?

 

 

Throughout your Acoustic Consultant work have you found rooms (presumably with more rigid boundaries than my room) that needed specialist "bass traps" that couldn't achieve good bass through positioning/multiple subs/EQ?

 

that is an amazing result 👍

 

Are you still using your T20 tapped horn or something else now?

 

cheers,

Mike

 

Yes, still using the bass horn.

 

Treating bass is difficult, that's for sure and bass traps can be a hard sell. With broadband traps that are practical, yes they may not be effective as low as people would like, but there is usually a worthwhile benefit that you can both measure and notice subjectively. The same can't always be said for tuned traps. I've seen examples where they were tuned for a narrow range without offering an audible improvement. I've seen better results with broadband traps.

 

 

 

The biggest issue for most people is being willing to dedicate considerable real estate and funds

 

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8 hours ago, rand129678 said:

I'm not an expert (I am a noob) but I read this by Harman Research

https://www.harman.com/documents/multsubs_0.pdf

 

For real world rooms, I think the best generalisations are:

 

1) One can be enough.

2) Placement is super important.

3) Extra sources can help solve problems not solvable by 2

4) EQ can really help deal with problems, but 2 and 3 hit the issue at the source

5) Getting good (representative) measurements, and getting a "flat" frequency response (no unintended lumps) is critical....  the way people typically view bass measurements understates the distortion.

6)  More sources obviously helps with distortion (both linear and non-linear) which people are often struggling with

 

So do you need more than one?   Eek... hard to say.    Just getting a second (one) and chucking it in...... is not a magic solve, by any stretch.

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