high pass filter for my drivers

[ibofite]

Hi all,

I planned to use winisd pro to calculate the correct high pass filter for the drivers i have chosen (2 ficar IB18 in a manifold). However, the program has many errors when trying to enter the driver parameters and will not allow saving the driver or doing any calculations. any suggestions how to get the proper filter specs?

also, would my yamaha YPAO be sufficient to set up the EQ, at least temporarily, for the IB instead of going through the complex eq process with manual measurements?

thanks in advance for any help.

[ThomasW]

WinISD doesn't like some of the specs of these drivers. Look at the ISD webpage to find the minimium parameters necessary to get the program to work. Sorry I don't remember them off the top of my head.

No one has asked about YPAO so I don't know anything about it. Do you have a link to info?

[ibofite]

thanks for the response. sorry, I don't know what the ISD webpage is.

 as for the YPAO, I don't have more info on it. However, it is just like audacity, or other auto set up for surround receivers but proprietary to Yamaha. I just wanted a good guess as to whether one of those receiver -auto adjustment programs will work at all to set up the IB sub eq. I guess I can just give it a shot.

still have to figure out what to do with the high pass filter. sorry I don't understand what the ISD page is.

[ThomasW]

ISD = WinISD, the program you're having trouble using to model the woofers and the hi-pass.

A Google search will reveal multiple WinISD tutorials telling how to use the program, including some you-tube videos.

These should get you started

redspade-audio.blogspot.com/2010/06/winisd-entering-new-driver-data.html
redspade-audio.blogspot.com/2010/04/how-to-us-winisd-pro.html

www.youtube.com/watch?feature=player_detailpage&v=Iz06TL33m9I

[gworrel]

If you go to help in Winisd, new driver entry is documented. In simple terms, enter the parameters in the order specified below and let the program calculate everything else. Here is the recommended procedure that will avoid errors and allow you to complete the entry:

The suggested procedure for entering driver parameters is following (check first that "Auto calculate unknowns" option is checked):

1. Enter Mms and Cms

This gives fs. If either is not available, then enter fs and other parameter.

2. Enter Sd, Bl and Re

Now, you should get all but Qms (and Qts), Vas. Please note that Vas may not match exactly what is specified by manufacturer, because exact value of Vas depends on environmental parameters. See FAQ.

3. Enter Rms or Qms.

Either one will do, although I tend to prefer Qms over Rms, because it can usually be measured in driver measurement procedures.

4. Enter Hc, Hg and Pe.

If Hc or Hg or either is available, then enter Xmax and optionally either Hc or Hg if available.

5. Enter number of voicecoils.

This procedure is most accurate. Also note that it also calculates true SPL (1W/1m) value. So it might not match the marketing SPL value, which is generally somewhat vague. Not in all cases, though.

6. Correct Znom, if necessary.

If there are several voicecoils, then you must be careful when entering parameters in that case, because many manufacturers give Bl in voice coils in series, because it yields double value for Bl against parallel connection. If driver manufacturer gives Qes, Bl and Cms or Mms, then you can check how Bl is specified. For that, you can enter following parameters to calculate Re: Qes, Fs, Mms or Cms and Bl. Connection mode can be changed by changing the combobox selection. The driver editor then converts Bl and Re values accordingly.

Equivalently, you can check for Bl by entering:

Qes, Fs, Mms or Cms and Re (for desired connection mode).

If you enter resistance for parallel connection and get about half of advertised Bl, then you know, that Bl was specified that way.

[ibofite]

thanks for the help. I actually went through the procedure and was able to enter the driver. however, I am not sure if the program is working correctly. the curve does not reach the xmax unless I enter in a much higher (system input power) than normal handling (700 w). maybe I entered something incorrectly? I checked it several times but thee are a few things that are confusing. does this sound right? the fi ib318 does not reach max excursion until driven with 700 watts? there are just so many variables that affect the curve. . .

Just a point, while I have searched and searched to find info on high pass filters, a lot of posts suggest getting more drivers (often many more) to produce more bass so as not to have to push so near xmax. this seems like an expensive way to deal with a problem that could be dealt with by using a well calculated high pass filter so you can push fewer drivers to the max without risk of overdriving. I really cant find a good discussion on high pass filters.  does no one use them? While I know there is some complexity to the calculation (room, sources and others) that affect it, cant you generally say that this driver (e.g., fi ib318) with this amp (ep4000) in a particular manifold design needs this frequency of high pass filter to prevent over excursion? it there really that much variation that tables could not be constructed to simplify the process?

Thanks for help in advance.

[ThomasW]

Instead of fixating on a HP filter how about posting info about the room? Proposed location for the IB. How loud you want the IB to play at the listening position, etc, etc?

That way we're answering a far less abstract set of questions.

[dmadesign]

I think you may have something entered wrong. I show you will exceed xmax with 500 watts each at 19hz. Look at the graph below, it shows 2 318'3 in a 1000 cubic foot box with 1000 watt total.

[dmadesign]

I'm showing 300 watts max per driver to keep it under xmax.

[gworrel]

I get the same result. 300 watts per driver with no need for a high pass filter. If you can limit the power, which the Inuke dsp allows you to do, then there is no need to worry about a high pass filter. Winisd will allow you to simulate high pass filters as well. Implementing them may not be entirely straightforward on some of the dsp devices. The Inuke series is limited to 20Hz but there have been discussions on Avsforum about how to work around that limitation.

[ibofite]

thanks so much for the help. I was worried that I entered something wrong into WINISD and though I checked it several times there are a lot of variables. thanks for screen shots. really helpful!

I have no idea yet what power level I will need to properly fill my room with beautiful bass. I see now why adding more dirvers could be a simple answer to the xmax issue.

as for my room- I currently use a Velodyne sub - it gets rumbly at higher level and hoping that the IB will be an improvement just in general.

room- I have a square room  (not the best I know but it is fairly sonically isolated from the rest of the house- so a trade off?) 17.5 X 17. it has a "knee wall" on the front and back walls (starting about 6 feet at approximately 45 degree angle about 4.5 feet long) to a 10 foot ceiling. the 119 inch movie screen on the front wall is butted up against the bottom of the front knee wall. I have three bass traps.  to the right of the screen is a 48 inch corner trap from floor to 5 feet high. two back corner traps (36 inches wide) to 5 feet. the left front- at the front wall, is the entrance - has an arched pass through then 3 steps down to the entrance door. I can't put a trap there and this area seems to be a problem. standing in the space between door and arch (about 8 feet ) -its like a giant drum that resonates with bass.

I also have about 6 acoustical treatments- diy-2x4 hanging on the walls at first reflection points- for mid-high frequency, a couples of small bookshelves and a room divider screen butted against the center of the back wall with some (roxul- all traps made of this) corner material inside a panel of the screen. the projector sits on a shelf on the back wall just above the (room divider) screen. the shelves and screen hopefully act as diffusers. I believe the screen (it is paper on a frame) reflects and diffuses high frequencies and absorbs some of the Lf.

I want to put the IB in a 2 driver manifold (fi 18s driven with europower 4000) , just to the right of the front bass trap (there is about 20 inches between the edge of the front corner trap and the left edge of the screen). I checked the best place for a sub using standard techniques and this seems perfect. there is an attic on the other side of the wall that is above the garage with easy access. I can make the opening for the manifold attached to two studs 16" apart.

So that is the room. any advice would be appreciated.

My drivers should arrive any day. I am not in a hurry. want to do it right. I have been reading and hanging out here for months, so I have the basic idea.