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-   -   New guy here with lots of bass related questions. (http://www.diyaudio.com/forums/subwoofers/86548-new-guy-here-lots-bass-related-questions.html)

looneybomber 15th September 2006 06:51 AM

New guy here with lots of bass related questions.
 
First off I am new to the forum, but I am not a complete n00b when it comes to HT stuff, however, I still have a lot to learn. If you do not feel like answering a question directly but instead want to give a URL, I will gladly do more reading! I just can't find the info I am looking for. :( I am probably searching for the wrong stuff but when searching for subwoofer preamp,

My first question.
When using winISD pro, if I input a speakers T/S parameters it keeps giving me some error message telling me none of my parameters are correct and gives me a list of everything I need to correct. How can I get that to stop when I am putting them in exactly right. I will even use other speakers that are currently in the data base as a template to make sure I am putting them in correctly and it still doesn't work.

Question #2
What are some good preamps to use for a subwoofer. What I am wanting to do is use a Crown K2 as my amp, but want at least a 7band EQ and a crossover with a variable frequency to use as my preamp. I do not want to waste money by buying a 31band EQ when I am only going to use the 7 lowest bands.

Question #3
Where can I find box and frequency response info on an Alliance 18, Sound splinter RL-p15 D4 and the Dayton Audio Titan 15. (If I had my winISD working, I'd be fine)

My goal is to produce 115db @ 20hz anechoic. At first I wanted 120db's but after further investigation, realized it would cost too much $$$ and the enclosures would take up too much space in my room.

If you have recommendations on any other sub, or even reasons to stay away from a Crown K2, I am all ears.

Thanks for your help

nunayafb 15th September 2006 07:11 AM

Quote:

When using winISD pro, if I input a speakers T/S parameters it keeps giving me some error message telling me none of my parameters are correct and gives me a list of everything I need to correct. How can I get that to stop when I am putting them in exactly right.
Unfortunately, you are not inputting everything right. Most of those values are calculated from other values-Qts from Qes and Qms etc...
and since winisd calculates some fields even though you entered data, it compares the two and reports an error if there is so much as roundoff difference.
So what you need to do is read the help file on "entering new driver data" and it should guide you as to what to leave blank and what needs to be filled in.

richie00boy 15th September 2006 07:51 AM

Post up the parameters you are using and maybe somebody can see where you are going wrong.

Just to add that 115dB @ 20Hz anechoic is unlikely to happen unless you use probably about 4 drivers. If you aim for maybe 102dB you might not be dissapointed.

looneybomber 15th September 2006 08:05 AM

Quote:

Originally posted by nunayafb

Unfortunately, you are not inputting everything right. Most of those values are calculated from other values-Qts from Qes and Qms etc...
and since winisd calculates some fields even though you entered data, it compares the two and reports an error if there is so much as roundoff difference.
So what you need to do is read the help file on "entering new driver data" and it should guide you as to what to leave blank and what needs to be filled in.

I will probably have to read that whole thing and experiment with what I can omit.

Quote:

Originally posted by richie00boy
Post up the parameters you are using and maybe somebody can see where you are going wrong.

Just to add that 115dB @ 20Hz anechoic is unlikely to happen unless you use probably about 4 drivers. If you aim for maybe 102dB you might not be dissapointed.

At 102db's I would cry myself to sleep. If you meant 112, I could live with it, but would always crave more.

I was hoping to use 2 drivers to help with the inroom FR and to keep from having so many localized spots of standing waves. Even with 2 Alliance18's or 2 RL-p15 D4's 115db's @ 20hz (anechoic) isn't possible? Another good question, would those be quality drivers for music?

As for posting up the T/S parameters, I was wanting to to a lot of experimenting with different tuning frequencies, Vb ect while trying to get a good EBS. If you still want them, I can go to the websites and get them for you.

So many more questions I could ask. Thanks for the help thus far.

richie00boy 15th September 2006 08:28 AM

Well all I can say is that WinISD seems optimistic on predicted SPL levels by upto 10dB in the bass.

2 18 inch drivers in a vented box might see you hit 108dB anechoic.

Your target might be met if you have some usable room gain, but for anechoic I think you have little chance with just two drivers.

looneybomber 15th September 2006 07:57 PM

Quote:

Originally posted by richie00boy
Well all I can say is that WinISD seems optimistic on predicted SPL levels by upto 10dB in the bass.

2 18 inch drivers in a vented box might see you hit 108dB anechoic.

Your target might be met if you have some usable room gain, but for anechoic I think you have little chance with just two drivers.

Looks like I may have to set my sights a little lower.

What about a preamp/eq for the Crown amp, any recommendations?

Collo 15th September 2006 10:13 PM

Quote:

Originally posted by richie00boy
Well all I can say is that WinISD seems optimistic on predicted SPL levels by upto 10dB in the bass.

The WinISD figure is for radiation into "half-space". Since most subs are not mounted flush with a wall, the "full-space" value is closer to what would actually be measured. Subtract 6dB to see what would actually be measured @ 1m.

richie00boy 16th September 2006 06:24 PM

Half space is when the radiating plane is cut in half, with a sub this would be the achieved by the floor. Fitting close to a wall would achieve quarter space. If in a corner it would be eighth space.

WinISD is just optimistic.

TwisterZ 16th September 2006 07:01 PM

i just read about this yesterday, check it out. It is a parametric EQ for subwoofer.

http://www.hometheaterhifi.com/volum...06-part-1.html

looneybomber 17th September 2006 12:05 AM

Quote:

Originally posted by richie00boy
Half space is when the radiating plane is cut in half, with a sub this would be the achieved by the floor. Fitting close to a wall would achieve quarter space. If in a corner it would be eighth space.

WinISD is just optimistic.

How many db's of gain to get from each reduction of space, half vs quarter vs eighth?


Quote:

Originally posted by TwisterZ
i just read about this yesterday, check it out. It is a parametric EQ for subwoofer.

http://www.hometheaterhifi.com/volum...06-part-1.html

That looks interesting. 5 variable bands would be awesome.


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