This time I am doing version up model 2A3/45 Transformer Drived Single Ended Amplifier
Driver tubes are 5687, double triode computor valves.consist 2 stages C-Couplig Drive.
C is using Toichi Vitamin Q oil paper capacitor.then drived by Inter-Stage-Transformer ISO TANGO
NC-20F.Audio OUTPUT Transformer are XE20S same as WE417A / 2A3 Single Ended Amplifier.
this amplifier is compatible for 45 and 2A3 valves.change filament voltage with one of Switch.
45 and 2.5 are same filaments voltages but power supply does not have regurator for filaments of eah other,
so have to reduce voltage for 45 around 0.5 V from 3.0V,
Max power is 3 W rms for 45 and 7 W rms for 2A3 getting from Transformer Drive.
45 sound feel like not 45 original sound from this amplifier.off course 2A3 single ended amplifier.
if same circuit using for 300B ,good enough 300B single ended amplifier than C coupling amplifier.
I thought , I feel ,sounding is 100 time good than WE417A drived amplifier.very clear
and good tight low but non NFB amplifier. feel like some low NFB Amplifier with NC20F
sound is need adjust with resistace of 2ary of NC20F(terminated resistance).
2dary of NC20F resistace are choose 47Kohm , sounding is 100 time better than open.
now I can use with termination resistance because drive amplifier has enough gain.
7119, E182CC , 5687,5687WB,7044 valves can be use as this driver.
1st stage's plate current is around 3mA and 2nd Stage is about 15mA,1st stages are regurated
by MOS FET regurator. 1st stages +B is 215V regurated by Zenner diode with 2SK1120.
each driver power supply are using Black Gate capacitor.
result: sounding is very natural and very clear sound getting.sound is very musical.
and not choose music,good for any kind of Music.getting good bass and mid, high are very
clear.if are you interesting ? please see schematic.sound charactor can be change with
load of first stage 5687 and cathode resistance of 2nd stages and B+ of 2nd stage.
2nd stage plate current is 15mA, this time I got good sound.but if going up 20mA does
not get enough high frequency response.7044 plate disspation is a little bit up so
be carefull to use.no same as 5687.if amplifier is osclation cause of high conductance
please connect 1K-7K ohm resistance between input and 1st grid circuit.same way
input of 2nd driver amplifier.indicated as Rp first one is 1.5K and 2nd one is 1.2K ohm.
if does not get noise when move potentiometer,It's not necesary to connected Rp resisitance.
2nd 1.2 K ohm Rp is very effective.sound quality are same.
Note: Yamamoto Noval socket is very expensive and very bad quality.I do not like
these kind of aficion product. Yamamoto socket are not so good. and made damege of
valves pins.why I did use ? because client would like to use.only one thing.
recently chinese valves socket are very cheap and very good quality.I do not would like
to use Yamaoto product any more. very bad.
these kind of amplifier needed at least 91dB/m/w speaker system.over 92dB is best.
Sound of this 2A3/45 single ended amplifier is very great.about 45 is like 2A3 single
2A3 is just like 300B single ended sound getting.what do you think ?
This Amplifier real cost is appx USD $ 5000 dollars.
Note:if would like export your product into south asia and china.they (transfer company
logistic company)does not care quality of merchandise. any thing throw a way ,,,,,,,,,
off course getting big dameges. chinese and south asian logistic company does not care
about package condition.if would like to send packages to these area, have a lot of
"big Risk".chinese logistic company is like thatChinese EMS
Is Inter Stage coupling Amplifier good ?
I said, I do not like sound of inter stage couplong amplifier.you can build up
good amplifier with C coupling and better than IST coupling Amplifier.
Inter Stage Type is only 2 thing is good
good bass and more power than C coupling Amplifier.
ただ、容易にパワーが取れます。2A3 であれば、7W 近く出ますし、魅力的です。音も帯域が狭くなりますが、