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post #181 of 200 Old 07-11-2017, 12:48 PM
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Well, that was the best sim shown at that time. In the meantime LTD showed a great sim that is even better because the frequency response is just as good as the H sim AND you get mechanical force cancellation AND it's easy and effective to eq because it's symmetrical. LTD's latest is better than the H in post 123.
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post #182 of 200 Old 07-11-2017, 03:50 PM - Thread Starter
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@LTD02 I was concerned about the motors in the same manifold hitting so disregard that.

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Originally Posted by diy speaker guy View Post
LTD's most recent drawing? No, I simulated that [edit] hasn't been simulated yet [/ edit], it still retains the big resonance problem.

I still haven't entered your actual driver specs into the sim, I've been doing everything with the same size box (whether it be U, H or W baffle) with the dimensions you provided in post 1 for the purpose of making all my sims directly comparable. Same size enclosure, same shape (overall), same power level, same drivers. The only difference is in the baffle wall itself, U, H, W shape.

I haven't done any tweaking to the sims to get the best possible response for a few reasons.

1. I haven't entered your driver t/s yet.
2. I don't know what you are going to do with the closet. Leave it? Tear it out?
3. I don't know your max dimensions and what you are willing or able to do to the house to make this happen.

You say you can't mod the rear wall of the closet at all - does it already have a hole in it?

What the max size of the "enclosure" that you can deal with? I'm going to need exact dimensions. A lot of this will depend on how big the existing hole in the wall is (if there is one), how many drivers you want per "enclosure", stuff like that.

I can get you a nice response but again, it would be better if you could measure you room gain curve FIRST so I can incorporate that into the sim. If you need help with that I can help you. And I need to know what kind of eq you have if any. Full dsp is always nice, and may or may not be required depending on what the room does to the response. As Vince said, it's not much use designing for a perfectly flat response if the room is going to shred it.

Another thing that hasn't been mentioned is that you can use a resonance peak at the top of the passband to very good advantage as Ricci has done with his MAUL and SKHorn designs. In that case you deliberately design a big fat peak into the response at/near the top of the passband and eq it down to flat. That give you less power needed in the eq'ed frequencies which is beneficial for a number of reasons.

How fancy do you want to get? Can you measure the room gain curve? Do you want extra sensitivity at the top of the passband so you can eq it down and make life easier on your drivers and amps? Are you absolutely sure you never will want to use the sub for both rooms on both sides of the wall? If not, why not? That's one of the biggest advantages to IB. Lots of questions before I start even thinking about doing final sims for you.
Room gain:150-50 +-3db 50-40hz -2db 30hz rising to 25hz hits +6db drops-2db at 20hz fairly flat to 10hz with slow rise after. I did this as close to Ricci's process as I could.

I only currently have 2 drivers with those specs I may change unless you think we can incorporate them with 2 from another maker. Im using a mini dsp and a ep4000 for the manifold the IB is currently in. Ill caught out any sheetrock needed for the mouth of the manifold, also the room is 3 block walls with sheetrock, the only framed is the closet wall.

The room opposite the theater does have a staircase leading out of it and is open to another area. If designing for both sides complicates it, theater takes precedent.

Sizes

Ported or sealed boxes each box can be 55"x32"x36" max

The IB as LTD sketchup could 120"L x 42"H x 24"D, doesnt have to be like that, but that will fill most of the closet.

Those sizes work and can leave the closet. After doing the room gain measurements I realized my room is more the issue and not necessarily the closet alone. I can remove the sheetrock if needed, it will never be seen and cover with fabric.
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post #183 of 200 Old 07-11-2017, 04:47 PM
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Quote:
Originally Posted by Gorilla Killa View Post


Room gain:150-50 +-3db 50-40hz -2db 30hz rising to 25hz hits +6db drops-2db at 20hz fairly flat to 10hz with slow rise after. I did this as close to Ricci's process as I could.
Could you post this process? Hope I didn't miss it.
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post #184 of 200 Old 07-11-2017, 04:54 PM
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Quote:
Originally Posted by Gorilla Killa View Post
Room gain:150-50 +-3db 50-40hz -2db 30hz rising to 25hz hits +6db drops-2db at 20hz fairly flat to 10hz with slow rise after. I did this as close to Ricci's process as I could.
So you took a small sealed sub and measured it outside and then brought it into your theater room and placed it where the manifold mouth would be and measured the response at the listening position and then compared the two graphs, with the difference between the two graphs being the room gain curve?

If so then please post the graphs. If not, that's how you do it.

I have a monster headache and I'm exhausted so I won't be doing any sims tonight.
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post #185 of 200 Old 07-11-2017, 04:55 PM - Thread Starter
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http://www.data-bass.com/data?page=content&id=80

My only concern is whether I had ample space from boundaries outside, being its the best I can do Im not going to dwell on if it is or not. It was either that or nothing.
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post #186 of 200 Old 07-11-2017, 05:06 PM - Thread Starter
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Quote:
Originally Posted by diy speaker guy View Post
So you took a small sealed sub and measured it outside and then brought it into your theater room and placed it where the manifold mouth would be and measured the response at the listening position and then compared the two graphs, with the difference between the two graphs being the room gain curve?

If so then please post the graphs. If not, that's how you do it.

I have a monster headache and I'm exhausted so I won't be doing any sims tonight.
I did 4 places and NONE were where the manifolds will be, duh. If I get off early enough Ill do it tomorrow, I was paying more attention to duplicating Ricci and forgot why I was doing it lol. Since Im redoing it whats acceptable distance from a boundary
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post #187 of 200 Old 07-11-2017, 05:32 PM
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Never mind the boundary, it's going to be there anyway where the manifold will be.

1. Take a sealed sub.
2. Measure it outside, say at 2m distance with the sub and mic at least 10m from any boundary.
3. Take it inside, put it exactly where the center of the manifold mouth will be. Measure it from the main listening position.
4. Take the two measurements and determine the difference between them. The difference is the room gain curve.

This room gain curve is only applicable when the source (sub) and listener (mic) are in those exact spots but it will help to get things rolling.

It's absolutely essential that you do the outside measurement, if you don't all you have is a room measurement, not a room gain curve measurement. If you are going to be cutting out parts of the wall that will change things too but just to get started follow those steps. Post the graphs if possible, and if you can do a difference sum with the software (not sure if that is available or not) to show just the room gain curve.
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post #188 of 200 Old 07-12-2017, 06:47 AM
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@diy speaker guy , does a close mic'd measurement of the sealed sub indoors not give an adequate picture of its response?

Gorilla, seems like it might be taking measurements at all the important seats, depending on how spread out they are, just to verify how consistent they might be?

REW definitely can add and subtract measurements.
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post #189 of 200 Old 07-12-2017, 06:55 AM
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Quote:
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@diy speaker guy , does a close mic'd measurement of the sealed sub indoors not give an adequate picture of its response?
I don't think you can eliminate room gain completely from the measurement even if it's close mic'ed. You might be able to diminish or even eliminate the room modes but I think the room gain is still going to be there in full effect.

Ideally I would like to see it done exactly as Ricci did it, starting with the sealed sub measured outside.

Normally we don't do this at all since subs are not usually fixed in location and could be used literally anywhere. So we usually just design for a flat(ish) response so the sub has a good chance of working wherever it's placed, in whatever location in whatever room or even outside. But in this particular case the sub is part of the house, the location is fixed and it will never move. So it just makes sense to design around the room gain curve so you have the flatest possible response from the get go.
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post #190 of 200 Old 07-12-2017, 06:59 AM
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Quote:
Originally Posted by Gorilla Killa View Post
http://www.data-bass.com/data?page=content&id=80

My only concern is whether I had ample space from boundaries outside, being its the best I can do Im not going to dwell on if it is or not. It was either that or nothing.
Somehow I missed this post entirely, sorry about that.

Boundaries in the outside measurement are definitely a problem, how far away was the nearest boundary?

There's always gating to eliminate the boundary effect but that adds further complication.

But if that's the best you can do then that's what we have. Just describe the measurement location (with boundaries and stuff) and we'll work with it. Also please post the actual measurement graphs and the sum/difference graph.

The issue I was concerned about was that you were not reporting much gain at all at the lowest frequencies. As Ricci's article shows, he measured a MASSIVE amount of gain at the lowest frequencies, something like 30 db (IIRC).

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post #191 of 200 Old 07-12-2017, 12:48 PM
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Quote:
Originally Posted by diy speaker guy View Post
I don't think you can eliminate room gain completely from the measurement even if it's close mic'ed. You might be able to diminish or even eliminate the room modes but I think the room gain is still going to be there in full effect.

Ideally I would like to see it done exactly as Ricci did it, starting with the sealed sub measured outside.

Normally we don't do this at all since subs are not usually fixed in location and could be used literally anywhere. So we usually just design for a flat(ish) response so the sub has a good chance of working wherever it's placed, in whatever location in whatever room or even outside. But in this particular case the sub is part of the house, the location is fixed and it will never move. So it just makes sense to design around the room gain curve so you have the flatest possible response from the get go.
close micing pretty much eliminates the room gain effect...

I took some measurements in this thread at the lp and close mic to compare since the room gain was just absurd..

https://www.avsforum.com/forum/155-di...nclosures.html
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post #192 of 200 Old 07-12-2017, 01:20 PM
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close micing pretty much eliminates the room gain effect...

I took some measurements in this thread at the lp and close mic to compare since the room gain was just absurd..

https://www.avsforum.com/forum/155-di...nclosures.html
Close mic works in a pinch. It is a little off from GP. Exaggerates the low end a bit and rolls off the top a small amount. Think of rotating the response
5 min clockwise with a hinge point near 50 or 60Hz. Good enough for most work.
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post #193 of 200 Old 07-12-2017, 02:25 PM
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My measurement mic broke somewhere around 2009, I didn't replace it until a couple of months ago and I still haven't taken it out of the box. So yeah, listen to the guys who have actually compared nearfield and outdoor measurement. I don't recall ever doing that particular exercise.
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post #194 of 200 Old 07-12-2017, 02:38 PM - Thread Starter
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First issue may be the sealed sub in question has a F3 of 66hz, its a 12"Dayton sho. I was probably 8m from a 2 story house, I know not ideal. I can set up elsewhere over the weekend if weather permits. Is close mic good enough and second do I need to use a different sub. Besides the IB drivers, everything else is ported. I can build a box if needed.
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post #195 of 200 Old 07-12-2017, 02:52 PM
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It's a lot easier to plug a port than to build a box. Your 12 inch sub should work though, as long as you can power it high enough to get all the frequencies of interest above the noise floor of your measurement system and the noise floor of the neighborhood.

If my math is right a reflection from a boundary 8 meters away will cause a notch at somewhere around 20 hz so that's plenty good enough. If my math is right.
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post #196 of 200 Old 07-13-2017, 08:15 AM
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If you have it setup to do GP at 1m do a close mic too. Then you will have both for comparison. Make sure there is no dsp or filters in the loop. Get a good 3 to 6 measurements of both to make sure it is repeatable and then you can average them to improve the noise rejection. If using REW use the longest measurement length. The dayton 12" should be fine for this. For the 1m GP measurement use 20v input for better SNR. Thats strong enough for good output but wont endanger the driver. Just need a dmm and run a 60Hz sine from REW. Start at a very low volume and adjust volume until you get close to 2v at the cabinet terminals. Then increase by 20dB in REW and that will be 10x voltage or about 20v.

For the close mic that may be too much for your mic input so drop back 20dB to the 2v level if so.
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post #197 of 200 Old 07-13-2017, 03:26 PM - Thread Starter
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Quote:
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If you have it setup to do GP at 1m do a close mic too. Then you will have both for comparison. Make sure there is no dsp or filters in the loop. Get a good 3 to 6 measurements of both to make sure it is repeatable and then you can average them to improve the noise rejection. If using REW use the longest measurement length. The dayton 12" should be fine for this. For the 1m GP measurement use 20v input for better SNR. Thats strong enough for good output but wont endanger the driver. Just need a dmm and run a 60Hz sine from REW. Start at a very low volume and adjust volume until you get close to 2v at the cabinet terminals. Then increase by 20dB in REW and that will be 10x voltage or about 20v.

For the close mic that may be too much for your mic input so drop back 20dB to the 2v level if so.
Its a plate amp sp1-4000, there are no external terminals. Is there a way to measure the slave out speakon and will that suffice or am I misunderstanding "cabinet terminals"
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post #198 of 200 Old 07-13-2017, 03:27 PM
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Its a plate amp sp1-4000, there are no external terminals. Is there a way to measure the slave out speakon and will that suffice or am I misunderstanding "cabinet terminals"
you can measure the slave out
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post #199 of 200 Old 07-27-2017, 06:14 PM
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@Gorilla Killa


just kind of curious if you decided which way you were going to go. any update?

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post #200 of 200 Old 07-28-2017, 07:25 AM - Thread Starter
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When I went to do the outside measurements again, as I was setting up i noticed my multimeter had quite a bit of condensation. I keep the AC kicking at 68 24-7 in the summer and the humidity from rain everyday nixed it, Ive been waiting so I dont have condensation on the avr and amp etc

I did do in room measurements, close mic, and I will say it opened my eyes to how much a room influences the low end. This in itself has me leaving all options on the table, horn,ported,Ib.

Im looking for good low end and midbass, the graph indicates the low end should be there regardless. That was a dayton 12sho and the low end is close to the same level as the the rest before it hits the F3.

The submaximus thread does make me think that should be an option, or a different design. This thread has been very informative, Ive read it at least 3 times . I would like to do this once and not second guess. Huge ported ,huge sealed, huge horn, huge IB. I have the room Im open to all suggestions, if it can fit in a 144"x28"x85" footprint.
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