Joe Mihok

So most of you know the story. I have a 194L SBB4 Tempest and finally broke down and got a Ratshack Analog SPL Meter. Anyways, I took the readings three times and got the exact same reading every time. This is the frequency response with both mains hooked up and crossed over to 80 hz with my sub. Is this normally how one tests for in-room frequency response ? Or do I unplug my mains ?

Here's what I get so far:



Is this a decent response ? Can a BFD flatten this out ? And if it could, would it be a drastic change ? During some movies the bass can get a little boomy and I'm not sure if it's the rooms response or just a poorly mastered movie ....

Hope you guys can give me some input. Thanks

GrahamT

Not pretty, but not unusual. Yes, a bfd would certainly help. You have about a 10 dB hump at 45 Hz, and another at 80 Hz. The BFD can take them down easy. You have a 5 dB depression at around 60 which may be a null. It is possible the BFD could help that, but you wont know till you try.

I run a FR sweep with only the sub, then only the mains, then both together to try to guess what the problems are.

Joe Mihok

GrahamT to the rescue again . I guess my next purchase will have to be a BFD.

Today I calibrated my sub with the rest of the speakers using AVIA. I was a bit thrown off during the subwoofer calibration because the sub uses a tone comparison for each channel in a 5.1 setup. I had different low frequency readings for each speaker. Here is what I had gottten from Avia:

Front left (which is where the sub is) - 71 DB
Centre - 72 DB
Front right - 75 DB
Rear left - 68 DB
Rear right - 68 DB

So what setting does one use ? I just took the setting from the left speaker comparison and made it flat with the subwoofer. This was done NOT using the corrected RatShack numbers (So I assume it's about +3db hot which is fine with me).

EDIT: I edited the Rear Left and Rear Right levels from 86 to 68. Too much bass tones affecting my brain .

GrahamT

Glad to help you Joe,
You can find the BFD at any local music supply store. You will need some 1/4" male to RCA female adapters. I think the BFD will make a big difference by just knocking down the two humps. no problem for 2 to 4 filters.

I use the S&V disc which might be similar. I set all the speakers to 85, master volume at 0 and then the sub to 85 dB uncorrected as well, a little hot. If you do some searches for avia, calibration etc, EdwardJM has made a lot of detailed posts on using the various calibration discs.

Joe Mihok

I answered my own question with AVIA by looking here:

http://www.hometheaterforum.com/htfo...AVIA+SUBWOOFER

Lots of great info in that thread . Should have done a "slow search" from the start.

MikeDuke

That response is incredibly close to what my sub was doing. But I have the krell showcase and it has a parametric eq built in. After I played with it I got a very flat response except for 63HZ down to about 25HZ. It just looked so freaky close to what mine was doing I had to say something.

I know what I like when I hear it

Joe Mihok

Well, it's reassuring you fixed your peaks ... it gives me some hope . I know every room is different, so I'll have to wait and see. Like Graham mentioned, I only have to calibrate a few frequencies and it should be fairly easy to do (or so I hope). The cost of a BFD here in town after local taxes will be around the $200 mark. That's fine and all. I've spent alot more on some HT gear, but it's just bad timing. If things work out and my car has no more problems, I'll be able to buy the BFD at the end of the month.

MikeDuke

"I only have to calibrate a few frequencies"
Agreed. I only did it on 4 frequencies.

I know what I like when I hear it

TonyWright

What software are you using to do these frequency sweeps?

I am interested in trying this out in my setup.


Thanks.

Tony

MikeDuke

I am not that high tech. I only used my radioshack SPL meter and the avia disk. But after a few hours I got it down.

I know what I like when I hear it