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[#5603] 單端胆機同好會 Yes, from my experience with the new digital amps, they are not perfect yet but they are getting close.		johnnykmtang 會員 70.xxx.xxx.22	2025-12-15 01:45

[#5604] 單端胆機同好會
Yes, full digital trend is booming. In this forum, 300B should never end.....

最後修改時間: 2025-12-15 02:24:21

niceday009

正式會員
42.xxx.xxx.28

2025-12-15 02:23

[#5605] 單端胆機同好會
#5597

E. 無負回輸OTL 胆機有4個過程
1. 分相
2. 电压放大
3. 电流放大
4. 合相
------

也有沒有分相的，我見下面是意大利設計OTL

最後修改時間: 2025-12-15 08:19:09

WilliamsonAudio

正式會員
182.xxx.xxx.61

2025-12-15 08:17

[#5606] 單端胆機同好會
Class D amp. 最大問題是影響系統中的其他器材，尤其喇叭/線沒屏蔽而線長落入開關頻率的話就更麻頻，本身的LC濾波作用並不全面，測量儀器例如AP等也需要加上AES特別的輸入濾波才能測出失真，否則很難看！現在的D.Amp.大多以hybrid形式出現，但未來好大機會以monolithic（做chip）的方法去做，現在已有類似的轉變，將來可能將此chip加在喇叭單元上作整體散熱和shielding,但犧牲左靈活性給diy'er和維修人員了！

mcc2018

會員
219.xxx.xxx.163

2025-12-15 08:30

[#5607] 單端胆機同好會
#5605 我見過類似，應該前面4枝电阻已構成电压比例式分相

最後修改時間: 2025-12-15 13:03:16

niceday009

正式會員
42.xxx.xxx.28

2025-12-15 12:54

[#5608] 單端胆機同好會
Psvane 845 reference PSE mono power amp

How can we tell this one is good? I found the schematic and I understand a bit more on its circuitry. The overall circuit isn't perfect but seems OK. Now, we do need to find out the quality of the components. The input, interstage and output transformer would be the key ones to check how they performs.

By testing of the THD and intermod distortion won't tell us much....

Johnny

最後修改時間: 2025-12-15 22:14:44

johnnykmtang

會員
70.xxx.xxx.22

2025-12-15 22:13

[#5609] 單端胆機同好會
Johnny has found the circuitry layout

I have found some abnormal connections, such as using interstage to connect the coupling capacitors in series. So not sure what intention the designer was thinking about. Having interstage to drive 845 capable to reach A2 and lesser distortion in A1, but putting coupling capacitor in series disable such benefit. Why do that ?

The amp use partial NFB loop covering first 2 stages, and 845 in zero feedback configuration . My viewpoint is still valid, except for old Chen 845 using totally zero feedback but the sound being harsh and bright, there is no other China made 845 in true zero feedback configuration covering from head to toe for aa the amplification stages.

最後修改時間: 2025-12-20 22:32:51

niceday009

正式會員
42.xxx.xxx.28

2025-12-20 22:26

[#5610] 單端胆機同好會
The Psvane reference 845 SE power amp can easily modifed for better performance - my believe.

1. Remove the NFB resistor or the capacitor.
2. The two coupling capacitors connect to the 300B anode instead. The Interstage transformer now work as the plate choke. This will improve the high frequency response.

Johnny

johnnykmtang

會員
70.xxx.xxx.22

2025-12-21 16:31

[#5611] 單端胆機同好會
Exactly, 買大陸制胆機你預咗要改，估記去設計果位自己都未必知何謂好聲音，自己都未必玩音响玩得靚聲，出到聲唔拮耳仔对他們嚟講已經係高標準

PSE845係欧美日屬於發燒級數最少賣三十萬以上，但係睇返呢对曙光PSE結構, 唔多似好掂

最快改善方式買对Lundahl 1677 1:2 3千蚊換咗佢对推動交連牛，拎走兩粒交連电容，删除負回輸，推動牛次級直接接入845栅，前面隻SRPP 6SN7改用下面果隻屏出，下面隻6SN7 陰極用粒Nichicon KG gold tune 或Super Through bypass 佢，680uF 50V

最後修改時間: 2025-12-21 20:29:46

niceday009

正式會員
182.xxx.xxx.197

2025-12-21 20:07

[#5612] 單端胆機同好會
我自己己經十多年不使用交連電容.
放棄用交連電容的原因是我使用了 Interstage.
但我也想講清楚不是所有的Insterstage交連牛都比交連電容優勝的。要知道如何選擇。
的确有很多交連牛的表現比用交連電容還差的。

wcw12

會員
119.xxx.xxx.24

2025-12-22 14:46

[#5613] 單端胆機同好會
wcw12師兄，好耐冇聽到你發貼，祝一切如意

niceday009

正式會員
182.xxx.xxx.39

2025-12-22 15:38

[#5614] 單端胆機同好會
Niceday師兄'多謝祝福，大家都如意！

wcw12

會員
119.xxx.xxx.24

2025-12-22 20:01

[#5615] 單端胆機同好會
Which one is better??? Interstage transformer vs coupling capacitor.

In general, using interstage transformer (IT) would have lower distortion than capacitor coupling with resistor load. Also, it can provide small amount of gain say 1.2~2 to boost in output signal. However, the IT has limitated frequency bandwidth and resonance at high frequency end. Having capacitor for coupling would have excellent overall frequency bandwidth. Capacitors are cheaper and much small in size.

So, a good quality IT would have wonderful sound at the cost of price, and size.

Johnny

johnnykmtang

會員
70.xxx.xxx.22

2025-12-22 21:53

[#5616] 單端胆機同好會
just some thoughts while i compared different load/coupling in my diy experiments......

when people makes comments on capacitor coupling vs interstage, most of them are actually comparing
1) resistor load on preceding stage and capacitor coupled to next stage; vs
2) using a conventional interstage trans to load preceding stage, as well as coupling to next stage.

the conventional interstage trans above actually serves 2 functions: loading and coupling. so, doing this comparison actually compare the SQ differences of i) resistive vs inductive load; & ii) capacitive vs inductive coupling. the comparison is not purely capacitive vs inductive coupling. as most of you know inductive loading is more favourable than resistive load on preceding stage, as a results, opinions tend to skew towards IT (i.e. #2 above).

最後修改時間: 2025-12-22 22:50:34

bambino

正式會員
61.xxx.xxx.40

2025-12-22 22:50

[#5617] 單端胆機同好會
Hi Johnny, I recap the #5230 that I once mentioned the pros and cons

Back to coupling and plate load for driving stage since this stage exposes the biggest problem, I categorize the type of coupling from the best to so-so in terms of performance

1. Plate choke, Direct Couple (The BEST, high AC impedance and voltage swing doubling, no coupling adverse factor) Komuro use this config

2. Interstage (high AC impedance, Voltage swing doubling, but now add an adverse coupling factor)

3. Resistor load, coupling cap (Much lower AC impedance, relatively higher distortion figure due to high voltage output, could be up to 7 times of induction load, also add an adverse coupling factor)

Your highly renowned Differential 5842 interstage couple 300B PP also doesn't use coupling cap but a decent interstage.To imagine using plate choke to replace interstage to enable the direct couple, may be it reach another level of purity

The quality of interstage induction coupling depends on core material, winding geometry, electrical properties of interleaving sheet

The quality of coupling capacitor depends on Dielectric material properties mostly

Theoretically original signal going through any type of coupling device would be worsen, not better. So Tube amp specialists trying hard to achieve direct couple is worthwhile

最後修改時間: 2025-12-22 23:59:52

niceday009

正式會員
42.xxx.xxx.28

2025-12-22 23:57

[#5618] 單端胆機同好會
分享 UK Audio note Andy Grove 在他設計的Ankoru PSE 845 power amplifier 文章的一段。

""""""Ideally transformer coupling between input stage and 300B would have been used but even super quality transformers impart a signature upon the sound (ultra mega quality ones don’t however) so a special copper foil capacitor with paper/oil dielectric was used to couple from 7044 to 300B. This capacitor like all caps has a sonic character but it was used to avoid a buildup of one type of timbre caused by the cascaded transformer coupled stages.""""""

他是用7044 cap couple 到300B牛推845