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Hello, is inuke able to aproximate linkwitz transform? If yes, how it's done? I've read Linkwitz is bassicaly made of several filters on each other, but found nowhere how to do it, especially on inuke.

Thank you
 

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I used a shelf filter on my Crown DSi to kind of do such a thing with a sealed SI18, it's was quite stupidly flat. Like you draw a line with a ruler, measured nearfield outdoors. I got it to about 15hz before it went down, and it sounded fine at reasonable volume. You would not want to stress it doing so...

having played a lot with EQ and shelf filters I'm not a fan of them. They are basically headroom limiters.

You can probably achieve much the same effect with your inuke if you just knock down 40hz with decently low Q, then layer on another one at say 60hz.

Try to get the curve so it knocks down 40hz and 60 hz and it's losing effect below 30hz- with very little/no effect below 20hz. A couple well placed cuts should get you about 90% of the way there. Then you can add EQ wherever measurements seem to indicate.
 

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Yeah the inuke does have the tools to get what you want. I assume it's a more flat curve- with compensation for the roll off of 12db/octave ???

You can either boost the bottom, or cut the top. A shelf filter can be helpful. But really if you cut at 40hz, perhaps a second at 60hz with an even broader Q you'll get most of the way there. Then start adding a little EQ after that.

I'm not a fan of boosts more than 3db. They seem to do more harm than good.
 

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Depending on room size boosting the low end is OK. I have always had to use a boost due to room size. I have the 20 HZ boost of 7.5 and no problems. It takes additional headroom but, I have enough to get a good FR.
 

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linkwitz transform is possible on inuke dsp as well as the dcx2496. it is comprised of a 3-step process.


the first step is to apply a parametric eq to change the q of the sub to 0.707. this could be a boost or a cut depending on the q of the sub.


the second step is to apply the 12db/oct shelf filter. this will extend the f3 point as low as you would like. since the rolloff of q=0.707 is 12db/oct, if you were to add the full 12db that would extend the low corner down by a full octave (from 30hz to 15hz for example). if you add 6db that will extend it half (log) an octave. the key is to use the 12db/oct shelf regardless of how much boost you actually need. the 6db/oct option has the wrong slope.


the final step is to apply a parametric eq to change the q=0.707 to whatever you want the final q to be.


in practice and in most rooms, this is going to get all mucked up anyway, so simply eq'ing out the big peaks and then applying a little bit of shelf filter if needed to extend the low corner is really all you need to do.
 

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example:
um18 subwoofer in 4 cubic foot sealed box. red line. f3 is 28.5hz and qts=0.886
target is black line. this is what you want after the linkwitz transform. this is completely arbitrary for the example. it is qts=0.707, f3=17hz.




here is the raw sub again (red) with an ideal q=0.707 rolloff (blue). the first step is to try to match the blue line.
this can be done with a single parametric eq on the corner of the sub. in this case, we will use parametric eq: freq=35hz, q=0.88, gain= -1.9db.



once that filter is entered, the red line will match perfectly the blue line.



then we simply apply the shelf filter. in this case, i used +12db to extend the rolloff point a full octave from 34hz down to 17hz. you are done! perfect match to target response!



if for some reason, you wanted a final qts that was different from 17hz, then a parametric eq could be used to change it (essentially doing the opposite of what was done in step 1).
 

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Discussion Starter #10 (Edited)
Thank you all for answers. I am planning a smallish sealed sub and i modeled with LT. I've read a lot of good stuff about inuke dsp, mainly the price/performance ratio and was planing to eq sub to accommodate room (as far as my skills go). I was wondering if i should build circuit with aprox parameters of what i have in winisd and eq from there, but it seems i don't need to do that and can do everything from inuke.

Thanks LTD02, that was exactly what i was looking for, i will definitely bookmark this until i get sub and inuke :)
 

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LTD02 Please give analysis:
PEQ filter 1
Q: 0.67
Gain +7.5
at 20 Hz

Filter 3
Q: 10
Gain -15
at 32 Hz

Filter 4
Q: 0.38
Gain -15
at 500 Hz

I get almost the same FR using Filter 1 , gain of +8, LS 12, at 30 Hz, Filter 3 gain -13, Q 7, at 35 Hz

I would like to increase the around 12-20 Hz output. Thanks. Room is large at 4300 cu ft + and measurements were taken at MLP.
 

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careful with the inukes- they do a poor job full range with speakers that vary in impedance.
Hmm, I am running my JTR215's full range with an Inuke 6000DSP and I feel they sound great. I certainly don't want to put words in his mouth, but RMK told me he was running his 215's and surrounds with a few Inuke NU4's and he said they sound just about the same as his previous Lab Gruppen!! Not sure if that opinion has changed or not?
 

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I would think swapping out that inuke for something that's known and measured to be better would be an interesting blind test.

I've always kind of felt that differences in amplifiers are not as great as differences with other things. I know a few people on these forums that have swapped out the inuke and said it was noticeable better. Some of those guys I know personally.

I don't usually put too much credit into things people say though. I've seen some dudes say some crazy stuff over the years.

My understanding of the inuke is the switching of the amp does not lend itself to very high fidelity on the top end (treble) when driving full range signals, especially when impedance varies or there is substantial content like bass at the same time. It's also not an amp that measures well, or has a very low noise floor. But if you can actually hear a significant difference or not ??? IDK. Might be interesting.

I think running those 215's of an inuke is like putting 85 octane in your turbocharged race car.
 

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LTD02 Please give analysis:
PEQ filter 1
Q: 0.67
Gain +7.5
at 20 Hz

Filter 3
Q: 10
Gain -15
at 32 Hz

Filter 4
Q: 0.38
Gain -15
at 500 Hz

I get almost the same FR using Filter 1 , gain of +8, LS 12, at 30 Hz, Filter 3 gain -13, Q 7, at 35 Hz

I would like to increase the around 12-20 Hz output. Thanks. Room is large at 4300 cu ft + and measurements were taken at MLP.

a high shelf with negative gain will increase your spl below 20hz fairly well. but as was noted earlier, that is going to eat up headroom (db for db) so unless you have a ton of extra sub/amp capacity sitting in reserve i wouldn't really recommend it.


type=HS12, frequency=20hz, gain= -??, where ?? is however much you want to boost it (note it is entered as a negative value for 6db gain, enter -6db).
 

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Thanks LTD02. I have 8 of the UM 18's but, I would still appreciate adding some headroom. I will give it a try and report the results.:)
 

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Thanks LTD02. I have 8 of the UM 18's but, I would still appreciate adding some headroom. I will give it a try and report the results.:)

sounds like you might actually have the headroom to spare. :)


here are what the gain profiles look like using that strategy with 6db of gain and 12 db of gain:




 

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I would think swapping out that inuke for something that's known and measured to be better would be an interesting blind test.

I've always kind of felt that differences in amplifiers are not as great as differences with other things. I know a few people on these forums that have swapped out the inuke and said it was noticeable better. Some of those guys I know personally.

I don't usually put too much credit into things people say though. I've seen some dudes say some crazy stuff over the years.

My understanding of the inuke is the switching of the amp does not lend itself to very high fidelity on the top end (treble) when driving full range signals, especially when impedance varies or there is substantial content like bass at the same time. It's also not an amp that measures well, or has a very low noise floor. But if you can actually hear a significant difference or not ??? IDK. Might be interesting.

I think running those 215's of an inuke is like putting 85 octane in your turbocharged race car.
I told you before when we ran mine off of Gooddocs Crown that I felt they woke my 215's up! I know some found them loud or harsh, but I thought they shinned, but I like a bright speaker and I have found I don't really care for EQ. I like a speaker raw. After the G2G, I guess it was about 5 days before I got the 215's back in my theater, but I was really curious to run them and see if I found they sounded different with the inuke and to be honest, I felt they sounded about the same as they did at Andrews. I am working on getting a new amp, but they just don't come cheap. I winded up ordering a new 215RM for a matching center channel and I also ordered the new Denon X7200WA (2.2) So an amp will be next. Personally the only reason I am really using the Inuke is because the house curve (DEQ) just works great for bass management. I would love to get the Crown IT5000, but they are very pricy. Certainly going to keep looking for a replacement but for now, I really don't have any complaints.
 

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LTD02 I tried it and the output was less. I did not add the 12 db. Where is that added? Twelve db is a lot and may will make a difference.:) I know the filters as a whole can be raised?
 
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