Howdy Neighbours,
Just fer giggles, let's try this:
..puttin' the DIY BACK into diyaudio...
Hun, so this is a REcreation of " "T's" Inverted GainClone ". It obliviously wasn't his, but rather somebody took his idea of an inverted gainclone power amp and thru a pot on the front ...
...
Doh! [1st Task: why is this 'amp' unstable? ]
So I recall T noting (re his power amp) that using an opamp [no matter signal or power] in invert. config. has some advantages:
A) You can choose the values on the +input so they match the -input's (better balance; tweak by actual measurement)
B) Invert. operation provides that nifty virtual ground that, because of the fet input, physically ACTS almost IDEAL [acting purely mathematical, with no real-world 'fudge' factor] and thus has these tech. advantages ... blah, blah, blah, ... I can't recall what he said.
...oh, oh , and I thought:
C) Well, because [in this particular case] the pot sets the input impedance, Rin and Rf can be dropped by an order of magnitude to provide better noise and more current through the resistors [and junction] that provides further benefit by ... blah, blah, blah, I can't recall what I thought. ;}
D) So I'd like to correct and develop this circuit and build it and do some basic testing and listening and ... and, d o i t m y s e l f , ... if ya know what I mean ...
Cheers from the
ALD
man!
PS And YES that's how yer supposed to spell n e i g h b o U r s!!11!1!
PPS It's not DOUBLE inverted .... Yet!
PPPS This project wasn't getting much traction in the Loungy thread sooooooooooo ..................
Just fer giggles, let's try this:
..puttin' the DIY BACK into diyaudio...
Hun, so this is a REcreation of " "T's" Inverted GainClone ". It obliviously wasn't his, but rather somebody took his idea of an inverted gainclone power amp and thru a pot on the front ...
... Doh! [1st Task: why is this 'amp' unstable? ]
So I recall T noting (re his power amp) that using an opamp [no matter signal or power] in invert. config. has some advantages:
A) You can choose the values on the +input so they match the -input's (better balance; tweak by actual measurement)
B) Invert. operation provides that nifty virtual ground that, because of the fet input, physically ACTS almost IDEAL [acting purely mathematical, with no real-world 'fudge' factor] and thus has these tech. advantages ... blah, blah, blah, ... I can't recall what he said.
...oh, oh , and I thought:
C) Well, because [in this particular case] the pot sets the input impedance, Rin and Rf can be dropped by an order of magnitude to provide better noise and more current through the resistors [and junction] that provides further benefit by ... blah, blah, blah, I can't recall what I thought. ;}
D) So I'd like to correct and develop this circuit and build it and do some basic testing and listening and ... and, d o i t m y s e l f , ... if ya know what I mean ...
Cheers from the
ALD
man!
PS And YES that's how yer supposed to spell n e i g h b o U r s!!11!1!
PPS It's not DOUBLE inverted .... Yet!
PPPS This project wasn't getting much traction in the Loungy thread sooooooooooo ..................
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Alllllmost therrrrrreee !!11!1!
😎
Go given that inductors are inherently hf blocking I just applied generic HF filt. to all inputs and outputs [except ps ...]
Also realized that thus there's way more that just the usual low level and PWR GND.
So it's a work in progress, ... er, ... will it explode?
.
.
.
...
.
.
.
No seriously ???11?1?® 😱
Cheers,
Jeff
😎
Go given that inductors are inherently hf blocking I just applied generic HF filt. to all inputs and outputs [except ps ...]
Also realized that thus there's way more that just the usual low level and PWR GND.
So it's a work in progress, ... er, ... will it explode?
.
.
.
...
.
.
.
No seriously ???11?1?® 😱
Cheers,
Jeff
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Not much farther now ...
And here's some more INTERNAL fiddlin'.
PS And I know of at least 1 mistake ...
PPS And where the hell's my DoubleDouble .... ☕
And here's some more INTERNAL fiddlin'.
PS And I know of at least 1 mistake ...
PPS And where the hell's my DoubleDouble .... ☕
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In all cases, the volume at middle the gain is less than 10. Go to the first post and replace the volume by 10k or less.
So now the double inverti .... S$SQUIRRELLL!!11!1!!
Oh I almost forgot:
https://www.ti.com/product/LM3886
View attachment lm3886.pdf
Audio input type Analog Input
Architecture Class-AB
Speaker channels (Max) Mono
Power stage supply (Max) (V) 94
Power stage supply (Min) (V) 20
Load (Min) (ohms) 4
Output power (W) 68
SNR (dB) 110
THD + N @ 1 kHz (%) 0.03
Iq (Typ) (mA) 50
Control interface Hardware
View attachment overture series amps AN 1192 snaa021b.pdf
View attachment SPiKe protection AN 898 snaa008b.pdf
View attachment measuring amp performance sloa068a.pdf
View attachment die datasheet snao202.pdf
View attachment amp power supply design AN 1849 snaa057c.pdf
Oh I almost forgot:
https://www.ti.com/product/LM3886
View attachment lm3886.pdf
Audio input type Analog Input
Architecture Class-AB
Speaker channels (Max) Mono
Power stage supply (Max) (V) 94
Power stage supply (Min) (V) 20
Load (Min) (ohms) 4
Output power (W) 68
SNR (dB) 110
THD + N @ 1 kHz (%) 0.03
Iq (Typ) (mA) 50
Control interface Hardware
View attachment overture series amps AN 1192 snaa021b.pdf
View attachment SPiKe protection AN 898 snaa008b.pdf
View attachment measuring amp performance sloa068a.pdf
View attachment die datasheet snao202.pdf
View attachment amp power supply design AN 1849 snaa057c.pdf
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Shhh ... let the others churn it over for awhile ...
[In Edjumication we call that short circuiting, not sure where that's from ... 😉]
Springsteen? Alex Steen from the Blues?
Stein!, stein is that it??
Not mine, just the newbs: when a kid wants to be smart and blurts out all the answers to 'beat' all the other kids; thus the other kids haven't even gotten into 2nd gear yet and learn very little.
Oh and that's Mr. Chief to you. 😉
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Nope, but good guess; just givin' people sumpin to chew on In The Meantime; will post full project soon ...
in the meantime - Bing video
🤐
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