Apparently you are using a Hantek DSO. The model has a maximum input sensitivity of 2mV/div which is a little bit better than the usual 5mV/div and you use this setting on the "output noise" screen picture in post 47. The readout seems to hint at a 100Hz (rectifier and supply, probably also filament related) fundamental residual, but it is not visible in the trace. Some uncorrelated spikes are visible of what seems to be mostly noise. In order to display residual hum properly, you need additional amplification as suggested before.
However, your hum may be well below 1mV which is fair enough (but it is not zero as you implied). For very efficient speakers it is desirable to aim at even lower levels and have a look at harmonic overtones of 50/100Hz (60/120 in other countries). This is not possible with your scope.
I appreciate your effort to build an amp in Shindo style using a rare german tube. My own creations are not of any interest here.
However, your hum may be well below 1mV which is fair enough (but it is not zero as you implied). For very efficient speakers it is desirable to aim at even lower levels and have a look at harmonic overtones of 50/100Hz (60/120 in other countries). This is not possible with your scope.
I appreciate your effort to build an amp in Shindo style using a rare german tube. My own creations are not of any interest here.
to _audio
Noise is not generated by the amplifier. I didn't mean that I need your help. Almost everyone knows this about the scope. You had previously asked me to publish the f2a se schematic ... Unfortunately, it is not possible, that is my business in iran . Now someone has liked your last post and lives in my country. He has been looking for information on winding out put chokes for years. I would really like to publish detailed information even about f2a out put chokes... But it is not possible.
Noise is not generated by the amplifier. I didn't mean that I need your help. Almost everyone knows this about the scope. You had previously asked me to publish the f2a se schematic ... Unfortunately, it is not possible, that is my business in iran . Now someone has liked your last post and lives in my country. He has been looking for information on winding out put chokes for years. I would really like to publish detailed information even about f2a out put chokes... But it is not possible.
Dear friend, the thing that you call it "Output Choke"!! is not some secret weapon anymore;
And believe me, just simply googling its proper name "OUTPUT TRANSFORMER", will lead you to a dozen literature including Patrick Turner's website, RDH4 , Wolpert's books, etc.. and it will give everybody all the information needed for winding an output transformer.
Ps I have designed a spreadsheet for calculating OPTs and other transformers and it is already posted here on this forum, you should search for it..
So please don't be like someone named Behnam, the famous fraud who sells his garbage amplifiers to people; I'm sure you know who I'm talking about.😉
My point was that you should not claim "zero hum and noise" (post 44). It is not zero,
this is not possible. If you know the schematic of Shindo F2a it may be useful for others
for repair.
this is not possible. If you know the schematic of Shindo F2a it may be useful for others
for repair.
to as_audio::If you know the schematic of Shindo F2a it may be useful for others for repair.
I have already written..... that everything I have built about Shindo... just from Searching the pictures of shindo . I have never seen a Shindo amps . Shindo has not published a schematics . You must know that the orignal manufacturer's diagram is only used for repair. so Shindo assembly pictures are available for you and everyone .I worked hard to be able to sell something.
I have already written..... that everything I have built about Shindo... just from Searching the pictures of shindo . I have never seen a Shindo amps . Shindo has not published a schematics . You must know that the orignal manufacturer's diagram is only used for repair. so Shindo assembly pictures are available for you and everyone .I worked hard to be able to sell something.
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The original amplifier he has cloned uses the F2a in Tetrode but the amplifier has feedback which deals with the high plate resistance.
Re post 65 : I will probably be able to investigate a Shindo F2a amp in the upcoming months.
Repairing a "Monbrison" preamp I found out that the phono stage has the same schematic as
in an old Telefunken amp, including a RIAA error.
Repairing a "Monbrison" preamp I found out that the phono stage has the same schematic as
in an old Telefunken amp, including a RIAA error.
Shindo built the amplifier based on a tetrode and 10 watts of output. Shindo was interested in local feedback. My clone has taken care of everything. But
some time agoI found a picture of f2a with normal feedback from the speaker output transformer .!!!!! Shindo was both working and adventurous in the design process. Shindo's method is a kind of realism and undoubtedly has no equal in sound.
If the amp is well constructed, a little of feedback should not hurt and reduces noises that another user could experience,
But seriously when the music is playing and we'll, a little hum hurts no one, my tube phone has hum because of the arm, but until I fix it somehow I live with it.
But seriously when the music is playing and we'll, a little hum hurts no one, my tube phone has hum because of the arm, but until I fix it somehow I live with it.
The feedback in this amplifier does not help . The first time the customer tested f2a clone ... it was with a vintage clipsch speaker. When the device was turned on, a little later .... there was a clicking sound of the tube heating up. There was no hum . People use sensitive speakers for a 10 w single end tube amp. There is no way to mask it .
Unfortunately, few tech friends talk about sound quality. It seems like everyone can achieve good sound !!! Your comments about Hm in music time are correct.