Skip to main content

DIY・自作 管共鳴 ( QWT / TQWT ) スピーカー パート 8 - このスピーカーによる10年間の実験で分かったこと / DIY QWT ( TQWT ) Speakers Part 8 - What I learned with this 10 years experiment with these speakers

DIY 管共鳴 ( QWT / TQWT ) スピーカー パート 8 - このスピーカーによる10年間の実験で分かったこと / DIY QWT ( TQWT ) Speakers Part 8 - What I learned with this 10 years experiment with these speakers

I have mentioned a bit on the prior post but after looking over, I found out that this craft was done around 2008, so we know now that this is a 10 years old craft. Originally it was done as an experiment, so if we take it from that perspective this could stand also as a 10-year span experiment. So I would like to write some conclusions inclusive of the years.
These speakers were just left at the corner of a room but the cone was clearly discolored. The same FF85K model bought as spare had not gone through the discoloring (wrapped in a plastic bag and boxed). Maybe we'd see some difference with a perfectly new unit, but by itself, I could not tell the difference. So it seems we could say that it would stay as it should with less humidity.
The stored spares are pristine till this day.
The dying of the cone by this agent I bought hasn't changed the sound almost at all likely because the agent only gave a negligible layer. I also tried it on a sheet of paper but it was very runny and did not give any thickness to the paper after it was dry, seeming it does not have damping properties of any sort.
The surface of the wood does not show any mold or smell. It's smooth to the touch and does not show any changes over the 10 years. Of course, it passed through 3.11 and fell over so some of the corners are chipped and such. One thing we can say is that the Bokujyuu is a pretty long-lasting coloring agent.
Next will be about the structure, but when you want to add a tweeter, basically you would like to have the unit that crosses with your tweeter to be as close to each other as possible, and that means mounting that unit close to the top edge of the box as possible. So, in this case, I wanted to know how far I can go. People that have ever designed a speaker might think that it's too close to the top panel, but that was my intent. The other point is that I wanted it as slim as possible.

There are many say about where a unit should be mounted on a Quarter Wave Tube but it seems there is no clearly established theory that the majority will be comfortable to agree on. Another reason why I wanted to have it mounted as close to the top is, as you can see in the photo, this enables us to have the rear panel some 200 mm away to minimize primary reflection. This is an effort to try avoid making it sound like it's in a small box.
Above is the measurement of the frequency response of the speaker. The measurement range is 20Hz to 20kHz, the orange being without a subwoofer and the blue being with the subwoofer. Normally the pipe should have a resonance of 47Hz or so, but since the speakers are crammed into corners, it seems to be resonating at a lower frequency. The dip from 160 Hz to 200 Hz is from the standing wave of the room. Even if it wasn't there the frequency response is declining toward the left and could clearly use more bass, so it seems for this length of pipe, a 10 cm (4 inch) unit or a 12 cm (5 inch) would be more adequate. But if you aren't shy of using subwoofers, this being a very slim speaker the stereo image is pretty outstanding so for those people 8 cm is also a good choice.
Just for your information, the subwoofer used was a Fostex PC-SUBmini2. Not like I planned to use Fostex, but simply it was small and cheap here. I have no problem with the quality of this product, but you might like to note that this will likely not be able to keep up with larger speakers. In any case, I am satisfied to have a quite high level of sound quality in this restricted space. Movies, games, and music are all very enjoyable so I would recommend if anyone thinks about trying. Recently there are good sounding Class D amps cheap as chips like starting from 20 bucks or so, and the speaker will probably outlast many of your digital gadgets.


So in the end, what would I do differently if I was to rebuild this model?
1. I would use thicker plywood or have it double layered such as two layers of 12 mm instead.
   You can feel the vibration from the box when it is at a considerable volume
2. Use a better terminal (speaker connectors)
   I would like to use one that has a better contact area to the cable.
3. Connect the front and rear panel all the way from the bottom to top
   For more structural rigidity
So basically since it went very well for an experiment, if I am to rebuild with the same concept I would want to simply spend more resources on it.


Popular posts from this blog

ハロー キティ マウスのDIYラインストーン デコ / Hello Kitty DIY Rhinestone Decor

ハロー キティ マウスのDIYラインストーン デコ / Hello Kitty DIY Rhinestone Decor 見出しの画像は編者ではなく姉の作です。当ブログ記事の家のリフォームのデザインを考えてる人ですね。以前からDIY好きを自称していましたが、実際やったら根気つづかないんでしょ?と思っていたんですが、なんと物凄いDIY好きだということが分かりました。まあ、この記事の写真を見てもわかりますよね。 ちなみに彼女のBlogはこちら。 荒木師匠オフィシャルブログ「荒木師匠の修行日記」 The top image is not mine (the writer) but by my sister. She's the one responsible for the designing of the house renovation on our blog. She's been telling me she loved DIY, but I was l ike "But you wouldn't last long if you actually do the stuff no?" but I was wrong. She really likes DIY. A lot. Well, you can already tell by the photos in this article. By the way, her blog is here . まず希望の色と大きさのラインストーン、専用の接着剤、とんがった棒っぽいものと爪楊枝が必要なようです。そして当然キティ様のマウス。デコったのがAmazonで売ってるけど死ぬほど高い(数万円だったかと)ということで一番安い普通のを買って自分でデコることに。皆様にもお勧めとしてはGoogleの画像検索で検索して(カタカナと英語両方で見てみるのを忘れないように)気になる画像を見てお店かチェック。そうすると大概の物が安く買えます。 First, you seem to need the rhinestones you want color/sizes, a specific glue for rhinestones, then a pointy stic

DIYリフォーム パート30 - 化粧 / DIY Home Renovation Part 30 - Cosmetics

DIYリフォーム パート30 - 化粧  / DIY Home Renovation Part 30 - Cosmetics 今回でとりあえず撮りだめた分は終わりです。窓をやりながら化粧をやっていったわけですが、ほとんどの壁は珪藻土です。例の ネリード というブランドのもので、非常に塗りやすくておすすめです。編者もこれ以前はコテで珪藻土をぬるという経験は無かったのですが、簡単すぎて拍子抜けです。広告費が出てるわけではないですよ!ただ、水性とはいえ床に落とすと拭かなければいけないので、それなりに体力は使います。 These are the end of the photos that have been taken for the moment. We did the cosmetics for the wall alongside doing the windows, which was done with the Diatomaceous earth that goes by the brand of Nerido , and is insanely easy to apply. I have never used a trowel before but it was to the level that it was anticlimactic. And I'm not paid to write this! But I must warn you, even though it's water-based, if you drip it on to the floor it'll get messy and you'll likely use a considerable amount of energy. 窓枠はまだ未塗装です。 The window frames aren't painted yet. ここの右側の耐力壁だけ一部壁紙が使用されています。中々アクセントになっていてオシャレです。 The structural wall you see on the right side has a wallpaper applied. It works as an accent and mak

DIYリフォーム パート29 - 窓地獄 / DIY Home Renovation Part 29 - Windows Hell

DIYリフォーム パート29 - 窓地獄  / DIY Home Renovation Part 29 - Windows Hell おっと、マイクロソフトの悪口はそこまでだ! 異常に窓の多い作りで建物の片側がほとんど窓という状況なので、以前の二重窓化の作業が延々と続きます。やってることは一緒なのでさらっとお写真だけ。 Stop right there! Enough badmouthing about Microsoft! The make of the house has an insane amount of windows on one side of the house so double windowing them on and on is what is done here. But since what we're doing is the same as the previous posts, so I'll just mostly introduce you the photos. 逆光で写真暗くてすみません。 Sorry for the backlit dark photo. 慣れてきてからは枠を作ってはめるようになりました。 After we got used to it, we started building the sill into a frame then attach it.  これは1か所分のオガクズです。何故かひどく見覚えのある光景。 This is the sawdust amount for just one section of the windows. But for some reason, this looks strangely familiar. トイプードルにそっくり。 It looks like a toy poodle. 立体化は見る見る崩れていくので非常に難しいです。 3D is a bit difficult since it starts to crumble as you go. そして熊。  And a bear. ここ暫く家の構造上