You are here

Log in or register to post comments
Hinti
Hinti's picture
Offline
Last seen: 6 months 3 weeks ago
Joined: Feb 28 2021 - 10:39am
Frequency drop at 102Hz

Hi, my Name is Juergen from Austria and I found this Forum on google.

first of all, my english is not very good, so please excuse ;)

My fav is to listen to music - Stereo 2.0. I have a small room but fet speakers. I don't buy according to room size, but according to my preference for great hi-fi equipment.

And I have already a good acoustic, but have a lot to do. At first "Bass-Absorber". What I have yet is, heavy curtains behind the Speakers. It has done the voice field good.

I have problems with some deep frequencies (the bass overturns much), at 41Hz, 63 and about 95Hz, also as at 123Hz.

So much for the introduction, but I found in wake of a frequency check, there is between 101 to 103Hz - a very strong hole !! (don't know the right english word: notch down? extrem frequency drop down - big hole...)

I have no specific absorber, disturber yet. But a lot of facilities, a carpet, wooden ceiling, Shelves, a television, a radiator, etc. But nothing in particular to suppress excplicit.

Can that be a room effect? I hope it's not from my stereo/sound system itself, because I have no cheap Hifi equipment.

that's my problem. Do you have an idea to this? do you need more info? please, just ask me. appreciative greetings, Jürgen.

Kal Rubinson
Kal Rubinson's picture
Offline
Last seen: 21 hours 3 min ago
Joined: Sep 1 2005 - 9:34am
Quote:
Quote:

Can that be a room effect?

Possibly. You should experiment with moving the speakers and your listening position to see if you can fix it.

Hinti
Hinti's picture
Offline
Last seen: 6 months 3 weeks ago
Joined: Feb 28 2021 - 10:39am
I will try that. But I can't

I will try that. But I can't well imagine, because deep frequencies are not directly, they usually spreads independently of the placement, in an undefined manner. So, if there is anything in the room, which absorb my 102Hz, I'm not sure how to find. But you are right, I must begin with test the speaker positions.

geoffkait
geoffkait's picture
Offline
Last seen: 1 week 1 day ago
Joined: Apr 29 2008 - 5:10am
Depends on where you measured

Depends on where you measured the frequency drop. It’s normal for the frequency response to vary by quite a bit around the room. It would also be very unusual for there to be a deep frequency drop all around the room. The main thing is to try to get a flat frequency response in the listening position. People don’t realize it sometime but they might be sitting right in the middle of a standing wave, etc. other areas in the room include room corners, upper and lower where high peak sound levels always occur. You might consider investing in something like thr XLOQ Test CD that has a very useful track on it for determining the very best speaker locations in a given room. Trial and error can only get you so far, it’s better to have a fool-proof method.

Hinti
Hinti's picture
Offline
Last seen: 6 months 3 weeks ago
Joined: Feb 28 2021 - 10:39am
okay, it's time to tell you

okay, it's time to tell you how I tested. I played with an online generator through all the frequencies, directly connected to my amp. so the test sound comes out from the speakers when I sit at the normal hear position. The test equipment are my ears (https://www.szynalski.com/tone-generator/).

So I decide by listening what kind of frequencies are to much. it works very great. My ears tells me reliable when a frequency is to much. and you are right, when there is an overturn, I can go around in the room, and it's for sure very very different.

But the hole when comes, the 102Hz, the volume goes down many many decibel. it gets very quiet. I almost don't hear this frequency anymore! Has my ear a defect? I don't think so. More tomorrow, when I did some tests...

Kal Rubinson
Kal Rubinson's picture
Offline
Last seen: 21 hours 3 min ago
Joined: Sep 1 2005 - 9:34am
Hinti wrote:
Hinti wrote:

I will try that. But I can't well imagine, because deep frequencies are not directly, they usually spreads independently of the placement, in an undefined manner. So, if there is anything in the room, which absorb my 102Hz, I'm not sure how to find. But you are right, I must begin with test the speaker positions.

Bass spreads omnidirectionally in an open space. Once you add walls, as in a room, the room dimensions create nulls and peaks at different frequencies (room modes). The position of the nulls and peaks are fixed by the room but you need to reposition your speakers and your listening position away from them, particularly the nulls.

geoffkait
geoffkait's picture
Offline
Last seen: 1 week 1 day ago
Joined: Apr 29 2008 - 5:10am
Hinti

Hinti said,

“okay, it's time to tell you how I tested. I played with an online generator through all the frequencies, directly connected to my amp. so the test sound comes out from the speakers when I sit at the normal hear position. The test equipment are my ears (https://www.szynalski.com/tone-generator/).”

I suspect you’re probably sitting in the middle of a standing wave/wave cancellation location. Can you measure relatively flat frequency responses in any other locations in the room? I once measured a peak frequency of 70 dB that was 6 dB greeter than the average in the room. I built a 15 foot long folded Helmholtz resonator to suppress the 70 Hz peak. As I alluded to earlier you don’t want any large peaks or valleys anywhere in the room if you can help it. They’re all audible from the listening position. Comb filter effect. Try measuring the frequency response in room corners sometime. You will be shocked to see how much higher the sound pressure levels are compared to the average sound pressure in the room at those frequencies, which can be high and/or low.

  • X