Interesting S/N Ratio of CD33!

Suddenly I have the thought of putting ALL the Chinese stuffs back into my CD 33 and see what the S/N ratio comes out.

1. Original Beijing 2C51 Tubes
2. Original BB 2604

What do you think I discovered?

忽發奇想, 將 CD 33 的原裝料放回去, 會得到什麼的 S/N Ratio?
1. 原來的北京 2C51 胆
2. 原來的 BB 2604.

你估到有什麼過癮的情況嗎? 以下開估 ....

Brothers, what do you think I will get if I replace the Beijing 2C51 with BENDIX 2C51?

How about using TWO OPA27AM to replace the OPA2604. What do you think I will get?

各位又估下, 如果用了 Bendix 2C51 代 北京 2C51. OPA 237AM 代 OPA 2604, 咁又會得到什麼的讀數?

Sorry, TWO OPA627AM replacing OPA2604.  Too hungry, typed wrong letters

Dinner finished. Back to my experiment.

Now I use a pair of Bendix NIB 2C51 to replace the Beijing 2C51. Both start with the letter "B". See how this "B" lives up to that "B" ....

飯就食完了, 遊戲再來. 用Bendix 2C51代北京2C51. 有什麼好看? 自己來看吧, 我無眼睇.

Experiment  # 3. Beijing 2C51 + One pair of OPA627AM.

See what will I get.

So dear Brothers, what do you think? I need not do the combination of Bendix + OPA627AM. It is definitely worse than the ORIGINAL Chinese combination.

The Question is, WHY? Is it because of the Circuit Design? Any comments?

各位大哥, 唔試都知 Bendix + OPA627AM 的情況唔會好得過大陸原配. 問題在, 為什麼? 是線路上的設計令 Bendix / OPA627AM 不能發揮, 或是其他原因. 只有請各位大哥教吓小貓, 不勝感激 ....

alfcat,

have you test by listening ????
any different ?

have you change the zener to 100v ??

thanks

alfcat,

I have upgrade my cdt-15a
the photo is enclosed.

thanks

alfcat,
the original cdt-15a photo

Dear Viewer,

So you changed the WIMA to Auricaps + Jensens. How much did you pay for this modification?

I haven't try comparing the Chinese Tubes + 6204 with Bendix + 627AM. Will try that later.

Very exhausting after a day's work and my work still haven't finish. Still need to mark exercises and set test papers ..... sigh

Dear Viewer,

I have changed the Zener to 100V already. Just listened to the THREE combinations I have used in the above experiment.

There is NO SIGNIFICANT better one. I would say it depends on your taste. The music sense for all three are pretty good.

Ha..ha.. I think I may be able to sell my Bendix and OPA627AM ... ha..ha..

Oh, I forgot to ask. How is your Cayin compared with your CD 33?

hi alfcat,


I changed the WIMA to Auricaps + Jensens the costs as follow:

Auricaps 2.2uf/400v x2 =       $320
Auricaps 0.1uf/400v x2 =       $160
Jensen e-cap 22uf/550v x2 =  $170
musiccap 0.1/400v x3 =         $225
                                        -------
                                  Total 885

jensen and musiccaps are stored one year old.
modified cdt15a is better than our upgraded cd33 a little bit on 3D an bass !!!!!!!!!
if both no modification I very sure that cdt15a is better than cd33 much.
You said have changed zener to 100v it is IN4764A ????
thanks,

Dear Viewer,

Yes, I have changed the Zener to 100V one; the one on the PSupply board next to my five BlackGates.

I asked my wife to listen for comparison as well. We concluded the following:

1. Pure Chinese Stuffs --- Beijing 2C51 + BB 2604 ==> Piano in 陳潔麗 really stands out. However, the vocal part is not that 3D ... but still good and clear.

2. Bendix / OPA 627AM changed ==> High Pitch Instruments not that "sharp". Vocals more natural, more details than the Chinese Stuffs.

It is obvious that without touching the Capacitors, the replacement of the OPAM and the TUBES really makes a difference. However, after changing the PS and the Analog part capacitors (and let them run in), the difference is not that significant.

CD33 的分享

發覺在原裝的CD 33上, 換了OPAM 和胆的分別是顯著的. 但當換了電容之後, 這個分別便在收細. 大胆講句, 電容 run in 之後, 可以說是口味之分. 大陸料, 高音樂器似乎較為特出, 但人聱相對比了下去. 用了 Bendix 胆, 人聱較為暖和, 為真.

以上只是小貓心德, 非金科玉律, 請勿見笑.

Hi alfcat,
I found the web site as following

http://www.threesixty.hk/products.asp?bmenu=178&jb=00720074
they have cable for sell.
thanks.

Dear Alfcat,

As hifi fans i personally think that the quality of sound is more important than the measured reading. In audio, if you compare measure reading between tube equipment and the solid states equipment, very frequently SS equipment will give you better reading but the sound may not sound better.

I agree that after changing the good cap, the impact of other part like tube, power code may reduce. Before i cahnge to BG cap, my DIY power cord give a long difference/impact but after changing good cap, the power cord like not much doifferences already....

Hi alfcat,

I 100% agreed with windwss said that :

"As hifi fans i personally think that the quality of sound is more important than the measured reading. In audio, if you compare measure reading between tube equipment and the solid states equipment, very frequently SS equipment will give you better reading but the sound may not sound better."

I have replace the zener of cd33 from 75v to 100v. the sound is more stable ,detail and high notes  on great volume.
no much different on lower volume.

Thanks for sharing.

True. That is why I think we come to a stage that "ersonal Taste" is far more important than just readings.

I am not saying readings / measurements are not important. Yet, getting the sound from our CD actually takes more steps than getting it just from the Headphone. All the stages that follow will exert additional factor on the sound of the CD.

Frankly, I am pretty happy with BOTH settings. It is a bit of surprise to me the Beijing tubes now are more "compatible" with the Bendix. When I first got the CD 33, you really can't stop me from replacing the Beijing tubes.

Cat and all,

Pay attention on the measurement, to get the basic requirement first.
Like S/N ratio. Frequency response, FFT analysis, and channel seperation.

Comment on original setting.
Do you know the GAIN in the circuit when you apply OPA627?
I will attach a important application note about opamp at another thread.

You get the good sound but you did not have good S/N, i.e. some of the "original small signal" must not be presented.

CAT, remember what I say in the class ?

KK.HO

Dear KK Sir,

What I don't understand are:

1. I used to have 75db after using the BG in the PSupply part. Now, with the same materials, the db dropped to only 65 or less.

2. The Chinese 2C51 + OPA2604 gave a reading of 89db. I just changed the TUBES to Bendix 2C51. Readings dropped to 65db already. I HAVEN'T change the OPAM.

Really want to know the possibilities of what went wrong with my CD.

我都話有90dB.如果部機得60幾dB我第一個吾買.



是否枝膽Bendix 2C51吾得,在邊到買,買時有無Check過工作狀態

DualXeon 兄,

我相信唔係隻 Bendix 的問題. 因為我也試過放隻 WE 落去, 後果也差唔多. 所以先覺得好奇怪.

Cat Sir


點解你確定D膽正常.

DualXeon 兄,

好問題! 唔好唔記得我是"老師"來的, 哈哈. 做實驗, 一定有 D CONTROL 要做.

1. 這對 Bendix 是由美國買回來的, NOS + NIB. 個盒一拆就"爛晒", 因為太陳舊了. 內有関於對胆的聲明.

2. 在不同的機上試過, 也用其他胆與它比較, 因都怕俾"鬼佬"搵笨. 用耳聽, 也用儀器測. 幾個大哥都覺okay.

3. 用其他的 Bendix 來比較, 不論耳聽或儀器度, 後果沒有大分別.

cat sir

本來寫左一大叠字,不過

寫文章時間長一點,大約5分錯後,按送出後變了登入,寫好文章無左.文章要寫過真無隱.

現在再無Mu寫.....氣頂....不過都要講,不如去   www.diyaudio.com    個邊高手多又會幫人,最好是個網吾覺有bug吾會寫好文章無左.文章要寫過無隱及氣頂. 最慘無人理.

Dear DualXeon,

Can't type Chinese on this machine. Thanks for the advice. Will continue to run the CD33 for another 100 hrs and see what will happen to the S/N ratio.