Every time I try to enhance the lm3886, the sound gets cleaner but goes back stage, as if the recorder microphone is placed far from the subject. I made a composite MOSFET +LM3886 to get single ended triode type sound
Post in thread 'Chip amp + MOSFET composite' https://www.diyaudio.com/community/threads/chip-amp-mosfet-composite.403832/post-7539252
The sound is very nice but far back staged.
I can workout to make this character adjustable as I know guitar accompany players do need to go background to let the voice of the singer to be on front stage by using probably reverb.
I need to know if such amp can be useful for instruments?
Post in thread 'Chip amp + MOSFET composite' https://www.diyaudio.com/community/threads/chip-amp-mosfet-composite.403832/post-7539252
The sound is very nice but far back staged.
I can workout to make this character adjustable as I know guitar accompany players do need to go background to let the voice of the singer to be on front stage by using probably reverb.
I need to know if such amp can be useful for instruments?
But you will not.
The MosFet as shown is within a STRONG NFB loop and its "triode ness" (actually "pentodeness") gets smashed by it.
You say so yourself:
"The universal circuit is shown bellow using LM3886 as simulation model compared to its application circuit. The Loop gain curves show how the initial 25db NFB@20khz leaps to 60db with MOSFET. The distortion is not implemented but the noise is. Comparing the output noise at 1khz, the 41.7uv of the initial circuit gets reduced to 0.7uv with MOSFET, this is 58 times lower which I estimate the distortion of the chip alone gets also reduced by the same factor."
Full amp will sound "very SS clean", not tube-ish at all.
About amp "going backwards" , it hints at something going wrong, big way.
You can adjust the required distortion by R4. Here what you get by 10k.
I have 3 examples of Chinese TDA2050-LM1875, $1.5 for 10pcs, using CCTV 48v 0.5A $3 supply you can make a 25W amp single floating ground supply.
you can parallel the R4 with mutiple selected zener pairs in head tail and get smooth saturation with selected level.
I have 3 examples of Chinese TDA2050-LM1875, $1.5 for 10pcs, using CCTV 48v 0.5A $3 supply you can make a 25W amp single floating ground supply.
you can parallel the R4 with mutiple selected zener pairs in head tail and get smooth saturation with selected level.
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Im not sure what the terminology back staged means.
If tested with musical instrument
Input impedance needs to be high.
1meg pretty normal for guitar.
Guitar Output impedance is around 8 to 12k
and then additional passive volume / tone controls.
So input impedance for preamp usually miles higher than what would be
expected. Because tone losses are pretty common with pickups.
Usually 1meg as mentioned
There is quite a few magical Fet
guitar preamp circuits on the net.
So magic tube circuits likely get lost in pretty
saturated market. line of products range from no name boutique guys
to established brand names.
Best sellers likely a affordable product with a real tube in it.
Hence a zillion other products with 12ax7 preamp of some sort.
Very saturated market as well, and endless junk circuits to ok ones.
If tested with musical instrument
Input impedance needs to be high.
1meg pretty normal for guitar.
Guitar Output impedance is around 8 to 12k
and then additional passive volume / tone controls.
So input impedance for preamp usually miles higher than what would be
expected. Because tone losses are pretty common with pickups.
Usually 1meg as mentioned
There is quite a few magical Fet
guitar preamp circuits on the net.
So magic tube circuits likely get lost in pretty
saturated market. line of products range from no name boutique guys
to established brand names.
Best sellers likely a affordable product with a real tube in it.
Hence a zillion other products with 12ax7 preamp of some sort.
Very saturated market as well, and endless junk circuits to ok ones.
Last edited:
Guitar Output impedance is around 8 to 12k
and then additional passive volume / tone controls.
So input impedance for preamp usually miles higher than what would be
expected. Because tone losses are pretty common with pickups.
Usually 1meg as mentioned
Guitar pickup DCR can be 8 to 12k, but the elephant in the room is the HUGE internal inductance in series.
That's why minimum load impedance in a single coil pickup is 250k, and 500k for double coil Humbuckers.
Of course, 1M is a general purpose value which serves all fine..
and then additional passive volume / tone controls.
So input impedance for preamp usually miles higher than what would be
expected. Because tone losses are pretty common with pickups.
Usually 1meg as mentioned
Guitar pickup DCR can be 8 to 12k, but the elephant in the room is the HUGE internal inductance in series.
That's why minimum load impedance in a single coil pickup is 250k, and 500k for double coil Humbuckers.
Of course, 1M is a general purpose value which serves all fine..
