Hi! Sorry for my english. Can you help me? I made SSA BIGBT rev. 1.1, it`s work, but I see not good on my oscilloscope. Bias in 100mA on transistir, offset is OK.
Why I see it? Thank you!
Why I see it? Thank you!
I see this on 1kHz. My load is resistor 75W 4 Ohm. Works on +-27V. I can`t buy in Minsk BF471\472, I used BD139\140
Circuit:
Circuit:
Last edited:
OK... 4 ohm is fine to test.
What is the level of signal in your scope picture ?
Also, do you have 100ma flowing in the 0.22 ohms when no signal and no load is connected ? So DC voltage of around 22 millivolts across these resistors ?
What is the level of signal in your scope picture ?
Also, do you have 100ma flowing in the 0.22 ohms when no signal and no load is connected ? So DC voltage of around 22 millivolts across these resistors ?
Yes, DC voltage of around 22 millivolts across 0.22 ohms resistors.
Oscilloscope works on 10v\cm. On next step on my sinus generator i see clipping.
Sorry for my english.
I know that this distortion can be if 100ma not flowing in the 0.22 ohms (low bias level). I can used 1A, but distortion there is. I return to 100mA.
Oscilloscope works on 10v\cm. On next step on my sinus generator i see clipping.
Sorry for my english.
I know that this distortion can be if 100ma not flowing in the 0.22 ohms (low bias level). I can used 1A, but distortion there is. I return to 100mA.
I'm afraid I've no quick suggestions on this. Does the distortion disappear below a given output level or is it present at all levels ?
(I can't see the differing transistor types causing this either)
(I can't see the differing transistor types causing this either)
Well I'm afraid I'm not much help on this at the moment because I'm struggling to see where the problem could be.
Do all four 0.22 ohms have 100mv across them ?
Is the board layout one that has been used successfully by others... in other words a tried and tested version... or is it one of your own ? (I ask that because I've not followed the thread, its the first time I've seen the design I think)
It is an interesting schematic, in fact its taken me a while to figure out the operation of it all.
I'll have a think some more on it but as before, at this moment I can't just think of any possible reasons for it behaving like this. It would be very unusual for any design to be component sensitive (with regard to type) to this extent.
I'll have a think some more on it but as before, at this moment I can't just think of any possible reasons for it behaving like this. It would be very unusual for any design to be component sensitive (with regard to type) to this extent.
Check the simple things first. I, for one, have mistakenly substituted a resistor value, off by a decimal point or more, and gotten strange results until I spotted the error.
Sheldon
Sheldon
If I use resistor 1K 2W (in shematic neat LED) I can`t set bias, I used 470 ohm, because I have +-27V. Maybe need to test amplifier on +-32V?
Lazy cat, in which 1K resistors?
Lazy cat, in which 1K resistors?
I started it in +-32V, everything works, but bias stable too long time - near 3 minutes.
In +-32V amplifier have no distortion. Many thanks🙂
It`s play music very nice, more better then Quad 405 and amplifier based on Sumo Nine Plus circuit. But Mark`s Alexander`s amp play music better, then SSA.
My next step is SSA on bipolar transistors, without mosfet. I think that this schematic is more better for music.
Lazy Cat, thank you for schematic. It`s very interesting!
In +-32V amplifier have no distortion. Many thanks🙂
It`s play music very nice, more better then Quad 405 and amplifier based on Sumo Nine Plus circuit. But Mark`s Alexander`s amp play music better, then SSA.
My next step is SSA on bipolar transistors, without mosfet. I think that this schematic is more better for music.
Lazy Cat, thank you for schematic. It`s very interesting!
Glad it's working now. 
In this sch input pair drives output BIGBT directly. Add VAS stage plus drivers and it will outperform any of your best amp. 😉
In this sch input pair drives output BIGBT directly. Add VAS stage plus drivers and it will outperform any of your best amp. 😉
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