SRA實踐篇：震頻、消震、調聲的互動關係
SRA實踐篇：震頻、消震、調聲的互動關係
我十分喜愛Da Vinci的Grandezza系統。除了Orpheus的Zero轉盤和Heritage DAC外是用上了Acoustic System Int’l的 防震木板，其如所有的Analog器材己用上了Ohio XL+2的 消震儀器。等了二個月，昨晚終於收到給Heritage DAC度身訂做的Ohio XL+2。
未為Heritage DAC用上SRA前，Intonation喇叭的主要變數制定如下：
Active Subwoofer的分頻點: 55hz
Roll Off Slope: 12db
Subwoofer Volume Level: 12 o’clock position
裝上後的第一個感覺就是全頻更加細緻，音色更加純美(例如French Horn和 English Horn的音色分別更加明確)，以及樂器與樂器間的前後左右感顯得更明顯而又不失和詣。可是總體平衡度變得有點太過嬌美，Belafonte和Bryn Terfel的雄壯喉底聲好像不見了。
此時我在思考問題的來源。我估計Acoustics System Int’l塊防震木板的震頻應在55hz至60hz之間，剛剛填補了Supravox Full Range driver大約在60hz便開始Roll Off的問題。再且，這木板的震頻可謂是十分自然和悅耳，所以有詣震都冇所謂。若我這個假設是對，那麼解決方案就祗有把有源低音的分頻點由55hz開始慢慢推高直至這部份的空洞不再存在。有老父的耳朵幫助下，我們把分頻點調至57hz，再經兩小時的不停試碟，我們應為在加了SRA在Heritage下是須要作出相對的調教，才能發揮全面的進步。消除了木板的諧震後所換來的就是更有節美奏感的中低，更有速度，更線性，中高相對地變得更清析，小提琴的聲尾豐富得來有速度。在協奏曲裡，左面一群的提琴組更是秀麗，既有動態，不失豐富音色。我須更多時間去確定其他領域的變化。
這經驗令我想起Mr.Zanden曾問我為何Marvel哥用了瘋狂Hi Fi架後，仍然用上了Acoustics System Int’l的木板在Tron的Syren前級？Marvel哥的喇叭是沒有Active Subwoofer的。若然塊木板的震頻是下約在57hz至60hz左右(這是簡單的假設，因為不同器材couple了上塊木板後會多少改變了原本單體的震頻點)，有可能他的房間在這週波有個trough，又或者他的房間仍有一段頗猛的中高頻反射，須要用木板的震頻來offset (開始進入Psycho-Acoustics的領域)。如此推論，Mr.Zanden家的木架震頻應該都是集中在此頻段，對於從前的Avalon以ceramic為中音單源的喇叭有offset ringing的作用。
音響世界可是無絕對，完全消震只是邁向正確方向的其中一環，不代表平銜度會自動調節變好，必須再用心思考研習各變數，繼而嘗試才能達標。
我十分喜愛Da Vinci的Grandezza系統。除了Orpheus的Zero轉盤和Heritage DAC外是用上了Acoustic System Int’l的 防震木板，其如所有的Analog器材己用上了Ohio XL+2的 消震儀器。等了二個月，昨晚終於收到給Heritage DAC度身訂做的Ohio XL+2。
未為Heritage DAC用上SRA前，Intonation喇叭的主要變數制定如下：
Active Subwoofer的分頻點: 55hz
Roll Off Slope: 12db
Subwoofer Volume Level: 12 o’clock position
裝上後的第一個感覺就是全頻更加細緻，音色更加純美(例如French Horn和 English Horn的音色分別更加明確)，以及樂器與樂器間的前後左右感顯得更明顯而又不失和詣。可是總體平衡度變得有點太過嬌美，Belafonte和Bryn Terfel的雄壯喉底聲好像不見了。
此時我在思考問題的來源。我估計Acoustics System Int’l塊防震木板的震頻應在55hz至60hz之間，剛剛填補了Supravox Full Range driver大約在60hz便開始Roll Off的問題。再且，這木板的震頻可謂是十分自然和悅耳，所以有詣震都冇所謂。若我這個假設是對，那麼解決方案就祗有把有源低音的分頻點由55hz開始慢慢推高直至這部份的空洞不再存在。有老父的耳朵幫助下，我們把分頻點調至57hz，再經兩小時的不停試碟，我們應為在加了SRA在Heritage下是須要作出相對的調教，才能發揮全面的進步。消除了木板的諧震後所換來的就是更有節美奏感的中低，更有速度，更線性，中高相對地變得更清析，小提琴的聲尾豐富得來有速度。在協奏曲裡，左面一群的提琴組更是秀麗，既有動態，不失豐富音色。我須更多時間去確定其他領域的變化。
這經驗令我想起Mr.Zanden曾問我為何Marvel哥用了瘋狂Hi Fi架後，仍然用上了Acoustics System Int’l的木板在Tron的Syren前級？Marvel哥的喇叭是沒有Active Subwoofer的。若然塊木板的震頻是下約在57hz至60hz左右(這是簡單的假設，因為不同器材couple了上塊木板後會多少改變了原本單體的震頻點)，有可能他的房間在這週波有個trough，又或者他的房間仍有一段頗猛的中高頻反射，須要用木板的震頻來offset (開始進入Psycho-Acoustics的領域)。如此推論，Mr.Zanden家的木架震頻應該都是集中在此頻段，對於從前的Avalon以ceramic為中音單源的喇叭有offset ringing的作用。
音響世界可是無絕對，完全消震只是邁向正確方向的其中一環，不代表平銜度會自動調節變好，必須再用心思考研習各變數，繼而嘗試才能達標。
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Comments
Yes, indeed I just got the SRA for the Wavac phono last night.
To me, the Craz rack and SRA platform are devices to reduce distortion due to internal (from the component itself, including transformers, mechanical parts, etc) and external (including the sonical wave bouncing back and forth, resonance, vibration from the rack due to action and reaction). Ohio is a component specific device whilst the Craz rack provides a generic platform.
I am using a wide rack which can house 6 components. Money aside, I would expect the sonical improvement to put all components on Ohio stand with an ordinary rack would be bigger than putting all components on a Craz rack without any Ohio. This is just a hypothesis without any scientific proof. My justification is that the Ohio has been designed based on the weight of the component and have considered the center of gravity, weight distribution, etc. So in terms of tackling the vibration energy across the entire frequency spectrum (different componet would have different vibration energy pattern at different spectrum depending on the vibration characteristics of its chassis, platform, feet, circuit design). Ohio should have a blanket reduction on the vibration energy across the entire frequency spectrum. As a result, I can hear more clarity and serenity between notes across the whole spectrum but not specific to certain range or type of music.
On the other hand, I think Craz rack has been generically designed without a pre-requisite for the user to specify what components would be put on top.
Putting in quantative terms, let's assume Craz can deal with 90% of the vibration distortion. Relatively speaking I would put 95% for the Ohio. So one can have a feel on the relative usefulness of these two. If they are used in conjunction with each other. One should achieve a total of 99.5% (90% due to the craz, another 9.5% due to the Ohio addressing 95% of the remaining 10% the cannot be dealt with by the rack).
Again this is just a hypothesis on the percertage of improvement but I think this can fully illustrate how these two can work separately or work in couple.
Franck's platform has used wisely the specific characteristics of wood with hollows made inside the platform in order to form an energy drainage system and to some extent, it reduces the action-and-reaction effect differentiating it from most of the other platform which only superimpose the vibration characteristics of the platform onto the that of the component, if by chance it can net off some of the vibration by action and reaction effect, then it is regarded as good for a certain type of component. That is why people tend to use different types of platform for different type of components. Franck's platform, in this respect, is more balanced and less component dependent.
Marvel
Yes, you are totally right! SRA does not alter the characteristics of the Wavac phono, it just lowers the noise platform due to mechanism vibration to the next higher level allowing me to hear more musical details. Using my analogy above the jump from 90% to 99.5% is pleasantly noticeable!
Marvel
Do you have one under the Zanden dac? The power supply chassis generates a lot ringing noises.
I know Mr Zanden is using SRA in all of his components. In my case, there is physical limitation for me to use SRA underneath the Zanden DAC and the Syren preamp because they both sit in the middle layer of the Craz rack height of which does not allow me to do so.
What is your experience using SRA stand?
Marvel
Yes, I believe so. But I have no way to prove if it is true or not...Looking at the rack, it is not exactly the design of the Ohio and vice versa. My hypothesis is base on the fact that Ohio is built specifc to a component. I understand if you can tell SRA upfront what components you are going to put on the Craz rack, they might be able to built the rack with such taking into account. Not sure, better check with AE. I think using a Craz rack is a must if you are serious about music and how it would be degraded by phsical vibration. Adding one or two Ohio on the amp or source (just like what I did) is perhaps a bit of icing on the cake.
Marvel