- #61 [bambino], 18-09-18 11:33
- #62 [pluto2], 18-09-18 11:53https://www.review33.com/avforum/index.php?topic=92080522211322&post=20#message_reply
以前D高手去左邊。 在裏面学到野。。
Ck2007.. 前post 的preamp 電源牛巳瓜左好耐末整返。大陸xifu 砌的。小学level soldering..連fuse 都沒有用。(瓜左开蓋才見到上述horror scene)。在 之前post的 link 有講。 - #63 [an8m4], 18-09-18 12:41如有興趣,找個星期六攪個gathering飲茶聚聚,交流一下 : ))
最好有埋家訪,精彩了!
最後修改時間: 2018-09-18 12:43:04 -
- #64 [ck2007], 18-09-18 13:34自問DIY都係為咗負擔到得出成品, 沒有能力研究人家線路好壞, 最好有人試過推薦吾洗行冤枉路.
睇落DHT難度避免hum聲, 選擇低噪供電線路最緊要.
K&K audio有組合用4P1L, 好似幾實際, 有師兄提過coleman regulator. 請高手比D意見. - #65 [n19137], 18-09-18 16:27For my 2 cents experience, Coleman regulator VS Filament Choke LCL Filter
Noise(Hum) - Coleman Regulator Better than LCL but LCLCL can be same noise level as Coleman Regulator.
Sound Quality - LCL or LCLCL is win a lot!
Money - Coleman Regulator cheaper too much - #66 [n19137], 18-09-18 16:32LCLCL Fliament filter
- #67 [pluto2], 18-09-18 16:38http://www.bartola.co.uk/valves/2017/08/14/uv-201a-dht-preamp-revisited/
Ale Bartola 的線路現今最hot gah lah. :)
要简单D,其實不用gyrator (即電子choke), 連coleman reg 也不需要lah..如下圖. :)
1) 用3.3v 電池。包無hum! :)
LiFeo4 type 最好。 battery tech now greatly enhanced ah..
** sorry, battery should be in direct connection to filament, not via 47 ohms..**
2) 用01A, 不用考慮其它胆
3) B+ 百多廾百volt,up to you
4) 33k 1W .. play with 22k to 33k
5) 1k, play with it too..for cathode bias
6) output z is high, thus need hi z input amp (eg, tube amp)
Thats all. :)
最後修改時間: 2018-09-18 16:46:13 - #68 [n19137], 18-09-18 16:49Yes 01A can be used battery for Filament because it's filament current is only 0.2A. And also 5V battery is easy found.
最後修改時間: 2018-09-18 16:52:17 - #69 [羅密歐], 18-09-18 17:07#67 容小弟來個狗尾續貂。
3. B電也可用9V rechargeable電池,廿多塊串聯起來便夠,反正耗電應不超過10mA。
6. 加個cathode follower以減低輸出阻抗,用White cathode follower會更好。 - #70 [pluto2], 18-09-18 17:12agreed with #65 & #69 :)
如果interconnect cable 短及用high input z amp... then as is ..ok.. - #71 [bambino], 18-09-18 19:55#65
Noise(Hum) - Coleman Regulator Better than LCL but LCLCL can be same noise level as Coleman Regulator.
Sound Quality - LCL or LCLCL is win a lot!
------------------------------
n19137 hing,
what's the total H & uF in LCLCL to achieve the same noise level as Coleman Regulator?
i like passive filters (LCL or LCLCL) too. - #72 [thomasc2], 18-09-19 10:38用電池點燈絲最好能配合一個可較的自動充電線路,唔知c hings 有冇好介紹.我以前買落一堆26,十幾年來一直都想搵2V的鹽酸電池但都搵唔個到.
- #73 [n19137], 18-09-19 10:41bambino hing
the capacitor is better to use bigger than 22000uf in each Cap. I 'm using 47000uf.
Choke - that is depended on how many chokes are using in your passive filter.
LCL - at least 100mH for each choke.
LCLCL - you can use 25mH or above for each choke. - #74 [baker.steven], 18-09-19 11:14#72
Hi Thomas C-Hing, Is that possible to use regulator to drop down the Filament supply Voltage?
ie. Couple of 18650 batteries parallel > LT-1805 >DHT Filament.
最後修改時間: 2018-09-19 11:14:54 - #75 [pluto2], 18-09-19 11:34LT-1085 or alike is something to avoid with (unless being used as a ccs)...its output z is similar to the filament resistance, the problem is signal also goes through the filament in a dht...in this case highly likely that some noise will get injected or signal gets robbed out from going in and out of the 3 terminal device..thus non linearity will be introduced, hence, the need of coleman regulator for the rescue...
I discussed this effect and others in my thread on 1PK previously. (see link posted earlier)
LiFeO4 battery is the choice... just need to find a way to do it...or some Lithium based 1.5v...
最後修改時間: 2018-09-19 11:48:56 - #76 [pluto2], 18-09-19 12:32Thank you for bringing up LT1085, come to think of it...indeed it will be a good solution for LiFe04 3.3V battery based filament powering for 26 tube (and others), to be used as a current source in this case, passing 0.8-1.0A. :)
There are also other schemes, like filament bias with say three 3.3V batteries in stack going thru the filament and some cathode elements (R, SiC diodes).
最後修改時間: 2018-09-19 12:48:03 - #77 [welborne], 18-09-19 15:46一開始又全部都係tech talk,circuits,我就完全沒興趣再看下去了⋯⋯Poor me
最後修改時間: 2018-09-19 15:46:46 - #78 [pluto2], 18-09-19 15:51so true... sorry ..haha...
Thats pretty much it on the tech part from me... :)
I think buying that switchable 01a-26 is a good option.
最後修改時間: 2018-09-19 15:56:09 - #79 [CodyChan], 18-09-19 16:32奇怪點解無師兄講27膽嘅?
不知有無師兄砌過27前級呢? - #80 [n19137], 18-09-19 16:47因樓主起個標題是直熱管前級,但27是傍熱膽呀。
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