彙整 | 三月, 2007

德國全音篇之 葵花寶典 (十二) – 完結篇

28 三月

What a wonderful World

If you’re a Lowther fan please stay the course. It’s nice to live in a fan club to get lots of contacts and be exited of building the next horn this isn’t mean’t for you. Changing your speakers against one of those described here win produce a disaster supposed your system is a sophisticated one. Lowthers built in a horn show strengths as well as weaknesses, and you tuned the whole system to these. Throwing in a much more linear, direct radiating speaker will immediately bring up the lots of compensation you arranged. I don’t want to condemn Lowther, nor at all. Yet they’re today’s audio experience in wide range or, if you tolerate their lack of bass, full range speakers, and I simply hope naming the contrast might help you to find out the right one for you.Using o]d radio speakers is knocking at heavens door. Speed, transparency, accuracy, detail. low level information everything isn’t just better than ever, it’s overwhelming. Within this mags pages I’ve found already noted, “light-speed-fast speakers" J and I always wondered where those listeners got the idea. Lowther? VOT? Other horns? These indeed are slow compared to the best radio speakers. No matter how good your present system is, it will ask for steady improvements. You’ve already changed your amp and now are driving a 2A3 amp as presented by Joe Roberts (SP 15)? Well done, boy, but now it’s time to look for a faster and more detailed thing. Perhaps a 45 with a 417a or a 7788 in the first stage will do. I don’t know your system but this I know for sure: These speakers will bring up everything. Medjocre caps in the signals path, flimsy power supplies, muddy output transformers etc. – now you’ll hear them !

Saddling old radio speakers nothing is slow and easy. I started ten years ago and not a single component within my system stayed. First came a unique drive unit for my turntable which underwent several refinments meantime (see SP 10); a new step-up transformer followed; it took me five years to work out an amp whose lucid speed and bang-on-accuracy can match; the third preamp will be next. Just to give you an idea what might happen to you and your HjFi system. The ultimate speaker most naturally ends up with the ultimate search for components. It’s a journey, and I enjoyed every step I did, loved the fun and pleasure I never ever lived before, and the results in terms of music are stunning. It1s a wonderful world you’ll enter.

One last note. If by chance you find an old SE radio still working well be a nice guy, hand it over to a radio lover and/or collector and ask him for single speakers in return. Don’t crack them up! They give such an amazing sound and offer so much pleasure of listening, Great HiFi should sound like the best (tube of course) radio you ever heard" Vinny Gallo stated (SP 1). Precisely! I really love steam radio (that’s how we call it in
Germany) and even more after looking inside. Learned a lot enchanted by this sound, detailed and relaxed accurate but always on the musical side, and never boring. We’re out for dreams, aren’t we? Hope yours win fulfill. Mine did.

旺記十分欣賞德國博士的 minimalist approach。現在許多人不斷 go after vintage 德國喇叭,特別是 cinema type,越追越貴,例如 KL405,四、五年前不過六百美元一對。現在大概已經翻一翻。

想體驗德國全音的魅力,幾十美元找對 elliptical 的,在8 khz 以上加對 cone tweeter,已經很好。Cinema speaker 是 tune for 劇院的,中音怎樣 ? 去戲院睇過戲就知甚麽是 Cinema speaker。

That’s. Enjoy fullrange. Enjoy music.


德國全音篇之 葵花寶典 (十一)

27 三月

原來近兩個月沒有續 葵花寶典。OK,儘快把全文整理刊登吧!

Some more miles to go

Supposed you got your set of speakers nevertheless there are some steps to speaker heaven. Yougave them a run on an small flat baffle and they’re performing fine, ok. Yes, they will do in any kind of enclosure of about two cubic feet. Being a novice you can handle it that way and you’ll be pleased. Old wisdom however recommended a (nowadays) very unusual shape of cabinet setting proportions to 0.618 to 1 to 1.618. (These masses are common in old architecture too.) For two cubic feet this is about 9 inch deep., 15 inch wide and 24 inch high. Such a speaker has to be placed 12 to 15 inch above ground depending on your habits.Each material to build boxes will come up with a sonic fingerprint of it’s own. Today various kinds of MDF are preferred but I found them slowing down the speed of radio speakers. I also noticed a b1urring of transients. I prefer plywood, the thinner the better, the lighter the better. The back of the cabinet should be made removable, these speakers are rear mounted ones. I’m using a reflex cabinet with a circular port of 4 to 4.5 inch. diameter. At the end of a long road I tuned the port to 65 Hz following my ears. Multipleats make a stiff suspension causing a sharp resonance in closed boxes, and it seems to be not so bad to bring this down a little with a reflex port allowing the speaker to act more linear. For your calculation of the port use the old formulas based op the wisdom of Lard Rayleigh and Helmholtz . The Thiele/Small formulas are developed for today’s speakers and don’t fit here. Of course some damping is needed inside, and for me foam is fine. How much depends on the speakers you got, but with a removable backside it is possible to check this by try and error, consuming a little time only.The modern way is fixing the speaker to the box as stiff as possible but with old ones it’s just the opposite. Main drivers and super-tweeters come with a decoupling ring of felt (sometimes foam) and this is the only part of the speaker you can and should renew if necessary. Using plastic screws to fix the speaker is a good idea but don’t tighten them too much. Adjust the nuts with a little shot of glue to keep them down. Last not least: The papercones are sensitive to humidity, that’s why they’re covered with cloth in old radios. Always treat them as you would treat an excellent tube of that area .

除了 OB 外,旺記曾經 strictly follow Dr. Wilimzig 做了 2 cubic feet golden ratio 的箱。效果一般。後來做給 Coral Beta 10 的  “大雪櫃" 就是累積了做幾個箱的經驗。

旺記的分享是 : the bigger the better 。 像 Coral Beta 這些 low Qts 的單元,用大箱加 reflex port 或 passive radiator 效果就十分好。German full range 的 Q 太高,應用 aperiodic 。

木的使用,以前已經討論過,硬淨收水足的北歐夾板是上選。大廠使用 MDF的原因只有一個 –  cost control 。

再論 Flying Mole : 方波測試與音質的關係 (2)

16 三月


測試時是使放大器直接直往揚聲器單元,中間無分音器。這是旺記慣用的方法。相對來說,接純電阻没有 甚麼意義,除非要測量失真,出 report,但 diyer不需要自欺欺人,放大器最终要接一個 non-linear impedance,純電阻真的没有甚麽指導性。


唔駛講,單屏 2A3 最 revealing。Charlize 也不錯,有少少 “掘尾 “,Flying Mole 再次之,比較平淡。

如果睇圖,方波最四正的反而是 Flying Mole。2A3 overshoot 最過分。

Hifi 就是這樣,不要以為越傳真就越好聽。

理論上 越傳真就應該越好聽,越自然。

不過祇得部 amp 傳真,其他不傳真,有啥用?

其他不說,就講錄音。 聲音從大大個鋼琴傳出,用個吋幾大的咪頭的diagraphm隔空 pick up 小部份的 wavefront,你話有幾傳真?

旺記上週下榻杭州的 Best Western Hotel 在大堂等人的時候聽到有鋼琴 background music。一聽就知喺真聲,追尋來源,終於看見在大堂有一部自動彈奏鋼琴。

我地日日聽 真聲,真聲定 hifi聲根本一聽就知,因為多頻間的相位關係有根本性的區別,multiway 就係死嚮呢度,全音叫做稍好。

話說回頭,因為在整個重播 pathway 都不傳真,適度的 " 刺激" 可以使聲音更 lively。當然,更 lively 不一定更 original 。

發燒的 bubble ,就是在此 setting 下 吹出來的。

講番 Flying Mole。

旺記因手上沒有 multiway speaker,所以無法下評語,但相信 performance 一定相當不俗,斷估的原因有二 :

1. multiway 因有分音器阻隔了 放大器的 damping,如果 multiway 的單元夠靚的話,會較易出好聲。

2. Flying Mole 力水很好, 旺記將 speaker impedance從 8 ohm 減至 4 ohm,輸出電壓毫無減少 – 即功率倍增也。因機不是自已的,所以沒有將阻抗再降低以免燒機要賠,但基本上要輸出功率從8 ohm 減至 4 ohm而可以倍增,許多一、兩萬元的成品機都做不到。一般 class AB 放大器的輸出沒有 4、5 對並聯是無法匹敵。

最後,相信 Flying Mole 推 horn 效果也不錯。Horn 聲已經很 ‘叫’,所以四正的 放大器有 “扶正"之效。許多人也用 gainclone 來推 horn,意義類同,八、九年前旺記測過 gainclone,typical SS amp ,直入直出也, rising edge 仲有少少圓邊,用來聽全音比較悶,低頻則很不錯。

BTW ,如果有日旺記發咗換大屋,買部 自動鋼琴好過買套卅萬 HiFi,又好聲又易保養又夠排塲。

再論 Flying Mole : 方波測試與音質的關係

13 三月

前幾天又去了杭州。近數月是差不多數週飛一次。恐怕祇會越來越密,大勢所趨,沒有辦法。近幾年來,旺記的想法是,人家給你機會,就要好好把握。這本是正常不過的,祇是回歸前十年,景太好,人都被寵壞了,現在夢醒了,還有氣有力,想點樣 ?

上月朋友借了他至愛的 Charlize Class D 和新寵 Flying Mole CA-S3給旺記兩週,旺記的 TAD300外遊,NS1000X在倉放年假,只好用 Feastrex D5nf 和 Jordan Jxr6HD 試聽一下。本來嘛,class D 應是與 multiway 共生的兄弟。


先看看一些測試吧 !

由上而下,分別是 Flying Mole,Charlize ,2A3 amp 。

如何解畫 ? 下回續。