Hi Brian,
I am not sure what your question is asking of me.
A base 'stopper' is normally intended to influence the high frequency response of a stage with regard to maintaining stability.
Parallelling with a capacitor will have no effect at LF, then there will be a region of frequencies where there is phase shift, then at high frequencies it is as if the resistor is not there, though there are other aspects to watch when establishing overall stability.
Whether Carlos bypasses those series output base resistors must relate more to the sum of the parts of his design. It takes 'hands-on' with the circuit to determine which components and values might be used, so I really cannot comment upon his own carefully made choices, and thus I could have no reason to criticise or discuss his decisions relating to the use of series resistors/capacitors.
Cheers ........ Graham.
I am not sure what your question is asking of me.
A base 'stopper' is normally intended to influence the high frequency response of a stage with regard to maintaining stability.
Parallelling with a capacitor will have no effect at LF, then there will be a region of frequencies where there is phase shift, then at high frequencies it is as if the resistor is not there, though there are other aspects to watch when establishing overall stability.
Whether Carlos bypasses those series output base resistors must relate more to the sum of the parts of his design. It takes 'hands-on' with the circuit to determine which components and values might be used, so I really cannot comment upon his own carefully made choices, and thus I could have no reason to criticise or discuss his decisions relating to the use of series resistors/capacitors.
Cheers ........ Graham.
Hi Nordic,
I wasn't thinking in terms of 50 pairs. WOW
However the more transistors you need to pair the better chance you will have due to there being much greater numbers to pick from.
I think if you tape your transistors to several sheets of A4 paper with those two digital multimeter figures below each one, you should be able to peel off very closely matched pairs to double check as you go along.
Cheers ........ Graham.
I wasn't thinking in terms of 50 pairs. WOW
However the more transistors you need to pair the better chance you will have due to there being much greater numbers to pick from.
I think if you tape your transistors to several sheets of A4 paper with those two digital multimeter figures below each one, you should be able to peel off very closely matched pairs to double check as you go along.
Cheers ........ Graham.
Hi All,
My experience has shown that vBE voltages are normally very close. A few mV of vBE mismatch is far less important than the beta mismatch.
Personally, I have never found vBE matching to be terribly useful unless there are serious issues, like the beta being far off also.
But, to each his (or her) own. If your pairs are not thermally coupled, who cares? Very important.
-Chris
My experience has shown that vBE voltages are normally very close. A few mV of vBE mismatch is far less important than the beta mismatch.
Personally, I have never found vBE matching to be terribly useful unless there are serious issues, like the beta being far off also.
But, to each his (or her) own. If your pairs are not thermally coupled, who cares? Very important.
-Chris
Well.... good matching will not be bad... if not the golden solution for sonics..also
cannot be bad..... as Nordic decided this way.... will be good to the folks will receive matched pairs... low off set is guaranteed... this is good.
I do not mind about small mismatches... continue to sound good despite of those small things...but i can agree that many small things mismatched or wrong.... added one to the other, may produce bad results.
What an envy.... you country has heatschrink tubes.
Hello Anatech.... you are very experienced .... if you say that VBE is less important than the beta matching.... i will be addicted to the gain matching from now on!..... because you have more hours doing this job than the aunts have cutting leaves.
Yesterday was a shame on me day!
I was trying two versions of amplifier.... one could produce 80 watts continuous without distort.... the second option 125 watts continuous before clipping.
I was evaluating, comparing and i have spent hours beeing very, very, very stupid.... i thougth the lower power had better sonics... very stupid that sittuation... the better idea was to compare them into the same level, not into the threshold of distortion.
I forgot, but my speaker... the one use to test... cannot work with more than 80 watts... so.... the smaller one was inside the limits... the speaker was distorting less than the big brother.
I was listening speaker distortions, not amplifier distortions...because the big brother was overdriving the speaker.
Reduce the power... the big brother sounded better... into 10 watts RMS peak.
We can be fooled... we humans have a lot of weeknesses... we fail, and this need a lot of care... not to evaluate wrong.
regards,
Carlos
........................................................................................................
Hey Nordic
Please, put a small piece of heatschrink tube inside the envelope that will contain my boards.
Dudainc.... send to him... he will come to Brazil at December, 18th... then he will mail to me using the high speed mail system... December, 19 i will have the heatschrink to put into a frame...good rememberings of my past in Japan.
Oh!.... i could not forget Akihabara.... the electronics place near Tokyo.... i felt alike sea sick.... the heart was beating 150 per minute.... enormous emotion to be there.
The Muslims goes to Meca.... audiophiles goes to Akihabara.
Image is a good use to heatschrink tubes.
regards.
Carlos
cannot be bad..... as Nordic decided this way.... will be good to the folks will receive matched pairs... low off set is guaranteed... this is good.
I do not mind about small mismatches... continue to sound good despite of those small things...but i can agree that many small things mismatched or wrong.... added one to the other, may produce bad results.
What an envy.... you country has heatschrink tubes.
Hello Anatech.... you are very experienced .... if you say that VBE is less important than the beta matching.... i will be addicted to the gain matching from now on!..... because you have more hours doing this job than the aunts have cutting leaves.
Yesterday was a shame on me day!
I was trying two versions of amplifier.... one could produce 80 watts continuous without distort.... the second option 125 watts continuous before clipping.
I was evaluating, comparing and i have spent hours beeing very, very, very stupid.... i thougth the lower power had better sonics... very stupid that sittuation... the better idea was to compare them into the same level, not into the threshold of distortion.
I forgot, but my speaker... the one use to test... cannot work with more than 80 watts... so.... the smaller one was inside the limits... the speaker was distorting less than the big brother.
I was listening speaker distortions, not amplifier distortions...because the big brother was overdriving the speaker.
Reduce the power... the big brother sounded better... into 10 watts RMS peak.
We can be fooled... we humans have a lot of weeknesses... we fail, and this need a lot of care... not to evaluate wrong.
regards,
Carlos
........................................................................................................
Hey Nordic
Please, put a small piece of heatschrink tube inside the envelope that will contain my boards.
Dudainc.... send to him... he will come to Brazil at December, 18th... then he will mail to me using the high speed mail system... December, 19 i will have the heatschrink to put into a frame...good rememberings of my past in Japan.
Oh!.... i could not forget Akihabara.... the electronics place near Tokyo.... i felt alike sea sick.... the heart was beating 150 per minute.... enormous emotion to be there.
The Muslims goes to Meca.... audiophiles goes to Akihabara.
Image is a good use to heatschrink tubes.
regards.
Carlos
Attachments
This Christmas will be great dear Nordic...your boards are very nice
And i will have tubes enougth to use and will put one into a frame...a good remembering.
By the way, dear nephew, have you already mailed some boards?... are there boards still travelling... say.... on the run?... will we have happy folks, receiving boards, soon?
Thank you, in advance, by your kindness.
Carlos
And i will have tubes enougth to use and will put one into a frame...a good remembering.
By the way, dear nephew, have you already mailed some boards?... are there boards still travelling... say.... on the run?... will we have happy folks, receiving boards, soon?
Thank you, in advance, by your kindness.
Carlos
Now i remember..... i have made those regulators, adjustable electronic stabilizers
and i have tried more than once to audio amplifier.... and result nothing special.
This explains why i have not those supplies anymore (I had not those last years).... because do not help to sound.... i could perceive nothing.
But those circuits are very helpfull, as you will have many voltages to many different circuits... also do not bother sound...just do not increase nothing.
Very hot here folks...very hot weather!
regards,
Carlos
and i have tried more than once to audio amplifier.... and result nothing special.
This explains why i have not those supplies anymore (I had not those last years).... because do not help to sound.... i could perceive nothing.
But those circuits are very helpfull, as you will have many voltages to many different circuits... also do not bother sound...just do not increase nothing.
Very hot here folks...very hot weather!
regards,
Carlos
Attachments
Sorry dear nephew, i could not understand the meaning
I tried to translated it literally... i have used google for that...but do not make sense to me.... i would like to know to smile, as usually you have nice kiddings with me.
Maybe some local culture kiddings.... literally translation do not make sense to me.
sorry, my ignorance about your language.
regards,
Carlos
I tried to translated it literally... i have used google for that...but do not make sense to me.... i would like to know to smile, as usually you have nice kiddings with me.
Maybe some local culture kiddings.... literally translation do not make sense to me.
sorry, my ignorance about your language.
regards,
Carlos
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