Hi
Has anyone ever encountered an imbalance in volume between their Leak 12.1 amps? I have a problem with one amp playing softer than the other one. I have swopped the valves between the amps but the problem remains.

Thank you kindly for the reply.

This morning I replaced the KT66 with 7581A and my first impressions are favorable.

After listening for 2 hours I find the sound is clean, chimey, delicate, focused and well balanced. Bass is slightly less (compared to GEC KT66).

I will say the GEC has a slightly warmer & natural tone.

The differences are small.

They are new production Tung-Sol 7581A.

I can live happily with them.

Other tubes are:
Mullard EF37A
Mullard ECC33 (yellow print)
Mullard GZ32

最後修改時間: 2025-09-01 17:51:45

Re. 1841

As checked the Duncan tube data sheet, 7581A has exactly the same pin-outs as KT66 (including G3 internally connected to cathode), and 7581A anode Va and Vg2 tolerance a are slightly better than KT66's. It should be a good substitute for KT66.

On added benefit is 7581A's heater current is 0.9A vis-a-vis KT66's 1.27A, i.e. it consumes lesser current.

Soundwise, you should compare by your ears and let us know your findings.

最後修改時間: 2025-09-01 14:03:27

According to the tube data sheet for 7581A it is "unilaterally interchangeable" with the 6L6GC. Should be good in Leak 12.1?

Hi
Can I use the 7581A tube in my Leak 12.1 instead of KT66?

I've been using 7581A in my Quad II amps without any problems.

7581A is said to be (from internet);

"an upgraded 6L6GC tube but willprovide more headroom than typical 6L6GC tubes. The 7581A power tube has a plate dissipation rating of 35W, as opposed to the 6L6GC and 7581 rating of 30W."

我又八卦建議一下

很不錯的

這種東西工廠用了廿幾年，我2019年開始就冇回到中國工廠

2017年最後一次安裝這種輪，在一些測試儀器底架下，質地不錯，好穩定，水平調教暢順

應該適合這個重型喇叭底座，如果高度適合都建議使用

嘩這位主人家好多有趣嘅玩具呀

Rcwy hing

多謝多謝

嘩對喇叭好靚

Haha 兄,

當你回香港, 有機會的話, 介紹你認識 FSM 喇叭的主人, 或許, 大家一起來吹水.

嘩好靚好靚

這種排版方法除了是對以往設計的一些尊重，這個年代我有一啲 marshall 膽結他 amp，都是這樣的

都幾十年人們累積零件與零件之間的排位幹擾等等等的認知增高了

是否還是一種在擴幹擾互相幹擾，可接受的設計呢？毫無疑問相比起其他的搭棚技巧維修各樣都是方便很多

真係好靚好靚

如果有機會可以分享一下 tannoy FSM 的聆聽感受就好了

thx you

最後修改時間: 2025-07-28 17:57:08

[黑仔] 外觀

朋友的一對仿造 Leak TL 12.1 "the Black" (黑仔)

Marino 的一對 TL12.1 推 Tannoy FSM 大型喇叭



最後修改時間: 2025-06-16 15:15:11

明白了

所以之後才有Stereo型號ST-20同ST-50

#1830

Thanks

Belafonte at Carnegie Hall (album recorded in 1959) is one of the first releases on the 1958 RIAA stereophonic standard.

Enjoy the stereophonic sound, which is even better than many new recordings.

https://www.bing.com/videos/riverview/relatedvideo?q=harry+belafonte+belafonte+at+carnegie+hall&&mid=CC5AB719CBD7E0F8109BCC5AB719CBD7E0F8109B&FORM=VAMGZC

最後修改時間: 2025-06-01 11:47:12

Re. 1828

Leak TL12.1 was produced in 1948-55(?).

At that time monaural was the standard (2-channel stereo was established in 1958).

最後修改時間: 2025-05-31 23:47:19

Can I use vintage Brimar 6L6G in the place of KT66 in the Leak 12.1?
----------------------------------------------------------

Duncan tubedata sheet shows that:

6L6 and 6L6G works at recommended maxium anode voltage of 360V for maximum 19W.

KT66 at max 500V for max 25W.

6L6GC at max 500V for max 30W.

Hence, 6L6G (and 6L6) is NOT recommended for Leak TL12.1.

Use 6L6GC or KT66 only!

Varislop II preamp - TL12.1 power amp

是否因為在單聲道年代 所以只需一部單聲道後級？

Hi
Can I use vintage Brimar 6L6G in the place of KT66 in the Leak 12.1?

有冇師傅可以幫手維修？Leak 12.1 ?