Question Increasing Slam from subs

Discussion in 'Subwoofers' started by i_raz, Jun 25, 2015.

  1. i_raz

    i_raz
    Well-known Member

    Joined:
    Feb 8, 2009
    Messages:
    4,089
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Stoke-on-Trent
    Ratings:
    +470
    I have a couple of si ht15 diy subs and was wondering how I could increase the slam from the subs.

    I have Dirac live which is reasonably flexible and I can adjust the frequency response. I understand that the slam region is around 60hz to 100hz.

    I have a attached 2 graphs from Dirac live for the sub, standard and calibrated.

    What would be the best was of doing this? How much db do I need to increase it by? I understand that you shouldn't eq a dip too much as it strains the driver.

    Also, if I increase the db for the sub, I assume that I would need to increase the same for the speakers around the crossover points?
     
  2. mattkhan

    mattkhan
    Distinguished Member

    Joined:
    Nov 14, 2005
    Messages:
    9,559
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Beckenham
    Ratings:
    +4,526
    No graphs attached :hiya:
     
  3. i_raz

    i_raz
    Well-known Member

    Joined:
    Feb 8, 2009
    Messages:
    4,089
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Stoke-on-Trent
    Ratings:
    +470
    Apologies I had problems attaching them. See below.
     

    Attached Files:

  4. i_raz

    i_raz
    Well-known Member

    Joined:
    Feb 8, 2009
    Messages:
    4,089
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Stoke-on-Trent
    Ratings:
    +470
    Attached some more slightly better quality graphs.
     

    Attached Files:

  5. i_raz

    i_raz
    Well-known Member

    Joined:
    Feb 8, 2009
    Messages:
    4,089
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Stoke-on-Trent
    Ratings:
    +470
    A couple more attached amending the target curve, one at the lower frequency and one at the higher frequency. This is just a very round amendment just to give you an idea.
     

    Attached Files:

  6. mattkhan

    mattkhan
    Distinguished Member

    Joined:
    Nov 14, 2005
    Messages:
    9,559
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Beckenham
    Ratings:
    +4,526
    The graphs are quite hard to read but that sort of sharp (high Q) transition is generally not desirable. Obviously your preference is your preference but I would have thought that lower mid bass shelf would be particularly offensive, it would also have the effect of masking the lower bass quite thoroughly.

    If I were you I would look at something like a 5-6dB rise starting at ~130Hz and ending at about 60Hz. This should accentuate the punch but maintain balance into the ULF.

    ISTR you have an inuke so you should note that this is a non trivial demand on your amp if you maintain overall volume level and boost the low end. What level do you listen at?
     
  7. i_raz

    i_raz
    Well-known Member

    Joined:
    Feb 8, 2009
    Messages:
    4,089
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Stoke-on-Trent
    Ratings:
    +470
    Just checking if these photos are better.
     

    Attached Files:

  8. mattkhan

    mattkhan
    Distinguished Member

    Joined:
    Nov 14, 2005
    Messages:
    9,559
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Beckenham
    Ratings:
    +4,526
    so basically just lift the hinge in that curve in that 2nd pic up and to the right

    it's at about {18Hz, +2dB} in the pic but move it to {60Hz, +5dB} and leave it flat beneath that
     
  9. i_raz

    i_raz
    Well-known Member

    Joined:
    Feb 8, 2009
    Messages:
    4,089
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Stoke-on-Trent
    Ratings:
    +470
    Thanks Matt. The original photos that I posted, I adjusted the target curve just to give an idea how much I can increase it by. I wasn't planning to increase it that much. Just wanted to know whether I was targeting the correct area when adjusting it.

    I have tried changing the target curve in the last photo by increasing it by about 3db between 60hz-130hz. Unfortunately, there is a dip (about - 6db) around 120hz which I can't reduce. Is this a problem being in mind it's - 6db? Around the 110hz, the DIP is reduced to about - 2db. I will be crossing my rear surrounds at 110hz, will this reduce the impact of the DIP at 120hz? I assume I will only be able to reduce the - 6db dip by moving the location of the subs (which I don't want to do). Is this target curve shown in the last photo better?

    I am using an inuke dsp6000 and I listen around - 10 to - 7. Just to clarify, are you saying that increasing the target curve places extra strain on the inuke?
     
    Last edited: Jun 26, 2015
  10. mattkhan

    mattkhan
    Distinguished Member

    Joined:
    Nov 14, 2005
    Messages:
    9,559
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Beckenham
    Ratings:
    +4,526
    if you maintain the overall volume level then yes, your power requirement has gone up because you want certain, power hungry, frequencies to be louder :)

    moving subs (in space or time) is the way to combat dips. You'd have to question the alignment of the sub with the main channel if that dip is at the crossover though.
     
  11. i_raz

    i_raz
    Well-known Member

    Joined:
    Feb 8, 2009
    Messages:
    4,089
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Stoke-on-Trent
    Ratings:
    +470
    Matt which post are you referring to please as there are a few pictures and im not sure which one you are referring to.
     
  12. i_raz

    i_raz
    Well-known Member

    Joined:
    Feb 8, 2009
    Messages:
    4,089
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Stoke-on-Trent
    Ratings:
    +470
    Bearing in mind the amp is 6000 watts in total, will this still be able issue?

    By time, I assume you mean the delay?
     
  13. mattkhan

    mattkhan
    Distinguished Member

    Joined:
    Nov 14, 2005
    Messages:
    9,559
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Beckenham
    Ratings:
    +4,526
    something like this

    upload_2015-6-26_16-44-23.png
     
  14. mattkhan

    mattkhan
    Distinguished Member

    Joined:
    Nov 14, 2005
    Messages:
    9,559
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Beckenham
    Ratings:
    +4,526
    It's not a 6kW amp by a long stretch. Long term output is 1200W per channel, ~1800W per channel achievable for a few hundred ms.

    yes
     
  15. i_raz

    i_raz
    Well-known Member

    Joined:
    Feb 8, 2009
    Messages:
    4,089
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Stoke-on-Trent
    Ratings:
    +470
    I didn't realise the power rating was so low! I'm sure on their website they mentions 2x3100 watts.

    I am trying the delay and will let you know how I get on. It's making some difference to the dips but I need to experiment further.
     
  16. i_raz

    i_raz
    Well-known Member

    Joined:
    Feb 8, 2009
    Messages:
    4,089
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Stoke-on-Trent
    Ratings:
    +470
    I have set the delay to one of the subs to 10.42ms and the DIP between 100-115hz has gone. Photo attached. There is still a 5db dip but that's at 120hz. I am planning to cross the rears over at 110hz and the sides at 100hz so hopefully that will be a good crossover point and the DIP at 120 hz won't matter.

    Do you think the attached graph is now reasonable starting point before I start amending the target curve?
     

    Attached Files:

  17. mattkhan

    mattkhan
    Distinguished Member

    Joined:
    Nov 14, 2005
    Messages:
    9,559
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Beckenham
    Ratings:
    +4,526
    Certainly looks better though tbh a narrow dip like that can be quite inaudible, or at least it is not a barrier to raising the target curve as a sane eq system will not try to boost into it. If it does boost into it then you just move the start of the shelf to avoid it.

    10ms is a hell of a long way, that is one whole cycle at 100Hz which takes you back, in phase terms, to where you started. The adjustment range should be more like within +/-4ms. Are you sure you can't achieve a similar response with a much smaller delay?

    Do you still have the ecm8000 (the mic from the sms-1) or are you just using a umik-1 now?
     
  18. i_raz

    i_raz
    Well-known Member

    Joined:
    Feb 8, 2009
    Messages:
    4,089
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Stoke-on-Trent
    Ratings:
    +470
    Thanks Matt. I tried a few different delays upto 20ms. I can't remember what the graph looked like at 2ms and 4 ms delays but certainly all the other delays between 6ms to 20ms(apart from 10ms) created more dips at different point. The 10ms seemed to be the best.

    I will try a shorter delay again when I get a chance.

    Will the 10ms impact on the sound quality? I never got round to testing it.

    I have both mics but I am using the umik. The graphs are from Dirac not rew.
     
  19. mattkhan

    mattkhan
    Distinguished Member

    Joined:
    Nov 14, 2005
    Messages:
    9,559
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Beckenham
    Ratings:
    +4,526
    try 1.33ms (give or take 0.2ms) and report back
     
  20. i_raz

    i_raz
    Well-known Member

    Joined:
    Feb 8, 2009
    Messages:
    4,089
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Stoke-on-Trent
    Ratings:
    +470
    Thanks will do.
     
  21. i_raz

    i_raz
    Well-known Member

    Joined:
    Feb 8, 2009
    Messages:
    4,089
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Stoke-on-Trent
    Ratings:
    +470
    You were spot on! I'm impressed! Tried 1.33 ms and it gives a very similar response to when I had it set it to about 10ms. I tried from 0.3ms all the way to 3.0ms but 1.33 gave the best response out of all of them. Graph attached.
     

    Attached Files:

  22. AngelEyes

    AngelEyes
    Well-known Member

    Joined:
    Mar 23, 2004
    Messages:
    10,617
    Products Owned:
    1
    Products Wanted:
    1
    Trophy Points:
    136
    Location:
    Detached from reality
    Ratings:
    +1,636
    If you want to increase the slam (assuming we are all on the same page with what slam is), then you need to increase the system Q. Take the drivers off, chuck in a couple of bags of sand or some other mass that won't rattle about and that will increase the snappy hit in the chest in the upper bass region.

    Fiddling with EQ will just make it louder at the preferred frequency and you will lose any detail either side of your hump, it won't make it it hit you any harder/faster just louder.

    Raising the Q will reduce the low end extension a bit though.
     
    • Like Like x 1
    • Agree Agree x 1
    • List
  23. mattkhan

    mattkhan
    Distinguished Member

    Joined:
    Nov 14, 2005
    Messages:
    9,559
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Beckenham
    Ratings:
    +4,526
    feel the powah of physics :beer:

    you had a sharp null at ~110Hz which was fixed by adding 10.42ms of delay. One cycle at 110Hz is ~9.09ms so 10.42ms is (10.42/9.09) * 360 ~= 412 degrees of phase rotation. You are therefore just playing one sub a whole cycle and a bit late at the crossover and hence you can back out 360 degrees (or 9.09ms) and achieve the same result in phase alignment terms at 110Hz. 10.42-9.09 is 1.33ms and hence you now have applied a small (52 degree) phase rotation at the crossover to bring the subs into a better alignment.

    Note that a time delay applies a frequency dependent phase shift throughout the passband but it gets increasingly small as frequency decreases so it is ~26 degrees at 55Hz, ~13 degrees at ~27.5Hz and ~6 degrees at ~14Hz. This means the effect, on the summed response, is increasing insignificant as frequency decreases.

    The phase difference applet in Wave superposition | AS A Level Physics Revision | University of Salford is a good visualisation of this effect which you might find instructive.
     
  24. mattkhan

    mattkhan
    Distinguished Member

    Joined:
    Nov 14, 2005
    Messages:
    9,559
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Beckenham
    Ratings:
    +4,526
    fwiw an Le adjusted model of that driver suggests it will be on peaky side anyway so I wouldn't be confident that that sort of changes makes a meaningful difference.
     
  25. markymiles

    markymiles
    Distinguished Member

    Joined:
    Nov 4, 2005
    Messages:
    6,137
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Caterham
    Ratings:
    +2,660
    Do you have a sheet with all the regularly used formulas for all your calculations or do you have them memorised. Would be great if there was such a quick reference.

    Not being lazy but most of the physics is long gone in my past and would like to know how to calculate some of this stuff. Like what you just did with the wavelength/time/cycle calcs, all the power, resistance, signal chain type stuff etc without having to ask you ;)
     
  26. mattkhan

    mattkhan
    Distinguished Member

    Joined:
    Nov 14, 2005
    Messages:
    9,559
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Beckenham
    Ratings:
    +4,526
    Combine memory with google for best results :D

    Period is just 1/frequency though
     
  27. mojogoes

    mojogoes
    Remembered (1961-2016)

    Joined:
    Oct 12, 2007
    Messages:
    10,469
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    166
    Location:
    Faraneverland
    Ratings:
    +1,984
    I concur with you here and its exactly what i found having the ht18s myself!! And another reason i built my enclosures giving the higher Q.

    In fact another reason ive taken out the underlay and added the fibre filling as its hitting / snapping so hard its making a hollow type of sound which will now be turned into heavy thuds.

    Yeah i also agree with you about it being just louder which with certain normal none action pact films / movies it won't sound to bad!! But with those in which have more content in between the big bangs and whistles will sound over baring , and like you have stated cloud other frequencies and those supposedly larger bangs.
     
    • Like Like x 1
    • Thanks Thanks x 1
    • List
  28. i_raz

    i_raz
    Well-known Member

    Joined:
    Feb 8, 2009
    Messages:
    4,089
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Stoke-on-Trent
    Ratings:
    +470

    Thanks guys. How much sand do I need to put in? You mentioned 2 bags, I assume you mean the size bags which you buy from wickes? I have attached a picture of one of the subs. You will note the driver is very close to the floor. Will this not damage the driver in any way having the sand in? Is there a particular way to put the sand in eg towards the back of the box away from the driver? Do I need to fill the while cabinet with sand, or just half of the cabinet?

    Also how much low end extension will I lose? I don't mind losing some as I have an earthquake 10b.
     
  29. i_raz

    i_raz
    Well-known Member

    Joined:
    Feb 8, 2009
    Messages:
    4,089
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Stoke-on-Trent
    Ratings:
    +470
    Matt Thanks for this. Very useful. I had to read it few times to get my head round it! I will also have a look at the link to.
     
  30. i_raz

    i_raz
    Well-known Member

    Joined:
    Feb 8, 2009
    Messages:
    4,089
    Products Owned:
    1
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    Stoke-on-Trent
    Ratings:
    +470
    When you say other mass, can this be anything as long as it doesn't rattle eg can I use bed sheets bed sheets, small pillow etc. Just wondering incase I ever need to take them back out it will be much easier rather than having to remove the sand.
     

Share This Page

Loading...