MJ Mini Tube Board

[digi01 0]

about the 2 transformers hook method,analysis here:

the 18VAC transformer directly powered the tube filaments connected in series.and the second step-up transformer converted the 18VAC to about 165VAC(transformer formula,U1/N1=U2/N2,220*18/24=165)which was then rectified and filtered with my power supply parts to output 220VDC.

 

the voltage trace: in 220VAC=>the first transformer=>18VAC=>the second step-up transformer=> 165VAC

 

 

[huangyong 0]

Which means the final voltage to the PSU is 165VAC, not 220V. So, there's no need to supply 24V into the secondary transformer, instead you uses 18V.

is that correct?

[digi01 0]

Which means the final voltage to the PSU is 165VAC, not 220V. So, there's no need to supply 24V into the secondary transformer, instead you uses 18V.

is that correct?

YES,165VAC is enough for B+ used.

 

 

[mukegile 0]

How bout the 6x4 rectifier filament ?..

Why don we simpy use... One input primaary 230VAC...with multiples secondary output ?

lets say...165VAC.--150mA for the B+ ...and 6.3VAC 2 A for the filament to be connected in parallel ?

 

 

 

[mukegile 0]

2.Part no. 159414

12VA 2x12V (S$12.00 each)

 

Guys...this one is not working...the specs of trannies is 230V or 115V primary with

2x12V seconday..., meaning it is a step down trannies...in real life application, u wouldn't want to work it as a step up trannies... ..

Edited August 19, 2004 by mukegile

[digi01 0]

Hi mukegile,

there are two rectifier method in my power supply board,one is solid diode bridge,the another is tube(6X4 or 6Z4).

as you know,the tube rectifier is high cost.it needs a special transformer for tube.the transformer is expensive

So,in the standard KIT,advice solid rectifier.

Edited August 19, 2004 by digi01

[digi01 0]

2.Part no. 159414

12VA 2x12V (S$12.00 each)

 

Guys...this one is not working...the specs of trannies is 230V or 115V primary with

2x12V seconday..., meaning it is a step down trannies...in real life application, u wouldn't want to work it as a step up trannies... ..

actually, B+ tolerates a big range of voltage value. from 90VAC to 160VAC, it will work. Slight voltage drop is not a major problem.

 

this is my first MJ mini tube amp.the transformers is standards 220V/18V and 220V/24V.

 

[mukegile 0]

great. tell us how it sounds...

[bpribadi 0]

Wow, a suprise in cake box ??? I don't mind to get one for new year present

 

We are waiting for your comment

[digi01 0]

Sorry,I cannot express my meaning well in english.So,I have to try post it in simplicity chinese encoding use GB.

 

 

MJ的声音特点：

给我印象最深刻的是中频，中音的声场非常好，细节丰富。

高音甜美，感觉象丝绸一样，很唯美很优雅。尤其是听女声独唱。小提琴的拉弦感非常真实！

低音不松散，但动态稍微弱一些。

总的来说，MJ不适合听大动态的电子舞曲，适合听流行，和品味古典。

另外，mj的声音好坏，很大程度取决于tube的品质。

 

 

 

 

[bpribadi 0]

Got to ask my wife to read it for me

 

In simple, do you think it sounds good? How about the bass compare to simple CMoy? I know that in midrange and treble tube will excels solid state.

Edited August 20, 2004 by bpribadi

[Mackie 0]

MJ的声音特点：

给我印象最深刻的是中频，中音的声场非常好，细节丰富。

高音甜美，感觉象丝绸一样，很唯美很优雅。尤其是听女声独唱。小提琴的拉弦感非常真实！

低音不松散，但动态稍微弱一些。

总的来说，MJ不适合听大动态的电子舞曲，适合听流行，和品味古典。

另外，mj的声音好坏，很大程度取决于tube的品质。

 

My translation:

 

Sonic traits of MJ:

 

"Quality of mid-range left the deepest impression on me; good soundstaging and details.

Highs are sweet, silky and depict refinement and elegance, especially with female vocals. Nuance of every bow movement on violin strings are realistically portrayed.

Bass control is tight but a tad lightweight.

In summary, MJ is not suitable for techno music but handles mainstream pop and classical music well.

In addition, potential of MJ's sound quality is largely dependent on tube selection and quality."

Edited August 20, 2004 by Mackie

[bpribadi 0]

Thanks a lot Mackie!

 

I wonder if we put Op-Amp buffer after the tube, it might improve the bass.

[digi01 0]

Hi Mackie,thank you very much.translation very clear:yes:

 

 

[N@Z 0]

Sounds like my cup of tea