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驻波问题求助 [复制链接]

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madog
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madog

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发表于 2004-03-05 04:53 |显示全部

重起 在 2004-3-5 0:47:08 发表的内容
一个计算低频陷阱/吸音材料（商品）的网站，给大家参考。
http://www.rivesaudio.com/PARCcalc.html



This site is designed for their distributing speaker system and not very
helpful to your case but it's nice to know.
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madog
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madog

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发表于 2004-02-17 14:44 |显示全部

重起 在 2004-2-17 0:13:59 发表的内容
madog 在 2004-2-16 23:39:11 发表的内容
[OK, tell me your ceiling height as well. Better still tell me your models of
equipments and cables. etc.

I'll let you know tomorrow. Got to go to bed.


Ceiling height is around 2.5m

CD player: Marantz CD6000 OSE
Int tube Amp: Mei-xing 3008 AB (300B driving 805 single end 40W x 2)
Speakers: Harberth HL-Compact
Interconnect cable: Audioquest Diamondback
Spk cable: Das Monitor copper 5.0mm bi-wiring

Have a good sleep, let music be in your dreams.



Sorry forgot to tell you. I think the booming midrange is come from your
speaker cable.

First of all, American interconnect is heavy in low register, soundsl  more
like a cowboy.

Your speaker cable if is of hard wire (single core) 5mm, this will become a
disaster. If it is true 5mm single core, midbass boom is heavy.

You may not change you interconnect but first change the speaker cable
if it is 5mm solid core.

Try some lighter weight cable, such as multi-strand but don't be greedy for
few hundred strands otherwise the bass quantity will be overwhelming
that will eventaully cover up the midrang clarity.

Same to power cord. You may sick to the original power cord well
otherwise thick power cord also contribute too heavy bass and midrange.

Cheers and have fun
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madog
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madog

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t T
发表于 2004-02-17 11:29 |显示全部

重起 在 2004-2-17 0:13:59 发表的内容
madog 在 2004-2-16 23:39:11 发表的内容
[OK, tell me your ceiling height as well. Better still tell me your models of
equipments and cables. etc.

I'll let you know tomorrow. Got to go to bed.


Ceiling height is around 2.5m

CD player: Marantz CD6000 OSE
Int tube Amp: Mei-xing 3008 AB (300B driving 805 single end 40W x 2)
Speakers: Harberth HL-Compact
Interconnect cable: Audioquest Diamondback
Spk cable: Das Monitor copper 5.0mm bi-wiring

Have a good sleep, let music be in your dreams.



Without any additional device to cut some unwanted bass boom, I'll let
you to ry the resonance cancellation method.

As there are points in the room the bass has some peak and dips. I think
the problem you have is mainly midbass somewhere around 150 to 400Hz.
And according to your present layout, the null frequency is on 29.45 and
59 Hz respectively where former one is half wavelength and latter one is quarter wavelength.

If you move your speakers more close to the back wall, the null frequency
will raise, for example if you wanted to null at 200Hz, you have to move the speaker as close as 0.62m to the back wall.

In this way, I will advise to firstly move your speaker backward or even simply attache to the wall. By doing this, the back wall will reinforce the bass
but the frequency will be very low and so not harmful to listening and
sometimes, it is good in certain extend where some people might like the lowest note of the pipe organ ? Of course, this will totally depands on the
whole system.

After have found the better positioning of the speaker then you may move
you seat back and forth to fin the least booming spot. That's it folk.

i would like to hear from you the end result.

Cheers and good luck
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madog
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madog

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发表于 2004-02-16 23:39 |显示全部

重起 在 2004-2-16 16:04:02 发表的内容
Thanks again buddy. My spks are shown as the 2 black squares at top of the layout. The original sitting position is indicated as the brown box, now a tad (~1ft) closer to the speakers.
[upload=jpg]uploadImages/20042161557448115.jpg[/upload]

The very LF is not a problem as my tube amp is not very capable of producing deep base. It's the resonance of the mid that is really bothering. I'll try base traps if they are the ultimate solutions, but it will be a lengthy process --- not very good at wood work      

BTW, Celestion 3 has nothing to do with this problem, as I'm now using Harbeth HL-Compact in this setup.

Your advice is highly appreciated.



OK, tell me your ceiling height as well. Better still tell me your models of
equipments and cables. etc.

I'll let you know tomorrow. Got to go to bed.
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madog
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madog

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发表于 2004-02-16 13:13 |显示全部

重起 在 2004-2-15 21:19:47 发表的内容
应该是，但厂方没有很多说明。
高质素的音箱自己这样乱垫高怕会影响低频或这个那个的，但Celestion 3反正没什麽低频，无所谓。




If you could give me where you put your speakers then I can advise
where will be your seat to avoid the most peaky low bass.

This is a method to null the peak by cancellation and was suggested to
me long time ago (say more than 15 years) and he had put it in his article
into the audio magazine.

Thou no the best but really help a bit
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madog
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madog

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t T
发表于 2004-02-13 14:11 |显示全部

KENTRYFO 在 2004-2-12 17:46:26 发表的内容
惨了，原来madog的中文水平跟我的英文水平有得挥！
谁说了：“The standing wave is coming from the CD recording  ”



The guy called AH TANG just few block ahead of your post. He said
"there is no 200Hz in Chai Jhian recording, may be midrange??"
It seems he doesn't believe the standing wave is from the recording.

He is right and wrong. There is 200Hz in the recording for sure but the
standing wave, so called RESONANCE is coming from the room. That
means there is no 200Hz peak in the recording but surely not midrange.

AH TANG psot is on 2004-2-12, 17:27:07, take a look for yourself.
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madog
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madog

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发表于 2004-02-12 17:41 |显示全部

阿邓 在 2004-2-12 17:27:07 发表的内容
[upload=jpg]uploadImages/200421217241452240.jpg[/upload]


“接近200Hz的驻波最是困扰---琴姐的独白”

蔡蔡的歌声中没有200Hz的东东吧？我想应该是中音。



The standing wave is not coming from the CD recording but the
dimensions of the room stimulate certain low frequencies that becomes a
peak level. In electronics, we called it resonance. Understood ?
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madog
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madog

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发表于 2004-02-14 09:44 |显示全部

KENTRYFO 在 2004-2-13 17:51:26 发表的内容
不好意思提我那房子，帖子上没有人拍砖很遗憾！——其实那是一堆破烂，真的，就是我在我所住的城市里面到拆建区拣回来的废旧材料垒起来的。况且我的要求并不高，在所费不多的情况下作的尝试。
真希望有一天楼上诸位亲临现场嬉笑怒骂一番！！！
可现在，我想请madog兄先在网上看一看。
madog兄：承蒙不弃，请进http://www.hifi168.com/bbs/article.asp?titleid=39496&ntypeid=10




Quite a nice room. Thanks.

The biggest challenge for audiophile is to spend least of the money to obtain the best result. Yes, at least for some guys do not have so mushc  
resources to spend.

Looking back to one of the guy's post, one of the article from Taiwan
saying how the room was designed and had it made.

That article is a typical audiophile's thinking as I've found they did not
consider the room as a whole but trying very hard to show us he is an
audiophile. This also true to some DIYers trying to put all the best (market
says the best) components in their equipment but at the end, sounds
terrible.

Spare parts is like a painting brush but the picture is from the artist or the
painter.
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madog
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madog

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t T
发表于 2004-02-12 15:37 |显示全部

重起 在 2004-2-12 13:37:08 发表的内容
madog 在 2004-2-12 13:01:41 发表的内容
You must built few bass absorber or bass trap to solve the problem as your
room has a lots of STANDING WAVE!!!

There are 10 standing waves in axial mode below 200Hz and
4 standing waves at tangential mode.

Axial mode : 22.8, 41, 45.6, 82, 68.5, 123, 91, 164, 114,  136,
Tangential mode : 46.8, 93.7, 140.6, 187.54,

There will be more if you have the ceiling height.

Remember, only bass trap would do the job

Good  luck, buddy

谢谢buddy Madog.
哇，你的回应好科学！
接近200Hz的驻波最是困扰---琴姐的独白
Any easy (and inexpensive) way to make a bass trap and where to put them?



The strongest peak of any standing wave is in every corners of the room.
You may put the bass trap by corners and is the most effective way.

Personally I would prefer the bass trap made as a wardrobe attached to the corner wall. These traps can be made rectangular of triangle shape depanding on the locations and designs. They are simple made from chip
board of MDF with fiber glass filled. However, it must be carefully
calculated for the target frequency and the board used also need some
datas such as the mass of the board per square feet of square meter, so
and so............

Cheers
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