Mine does not have the NFB cap and it's ok at 50 mV offset (that means 0.31 mW dissipation in 8R loads). I don't understand why do you want to increase these resistors. This would only increase noise and offset.
If I'm doing my math correctly...The output noise of the LM49810 is about the same as the input noise on my sound card, so I feel like there's a little room to play with. Maybe I'm wrong...we'll see.
Resistors are easy to de-solder and change.
--Greg
Resistors are easy to de-solder and change.
--Greg
These are correct almost for sure, but there are little benefits from increasing these if you get rid of the cap.
I'm planning to do a class A mosfet power amplifier and i'm worried about if having a high sink to source voltage ( 8 V ) could somehow degrade sound quality. The idea is to use three pairs of 2SK1530/2SJ201 with R33 emmiter degeneration, and the use of positive tempco mosfet is intentional since its almost impossible to prevent bias current from going down with temperature and it's rather easy to prevent it from raising.
Is the driver worth a class A output stage? Any advise?
Sorry for the double post
Is the driver worth a class A output stage? Any advise?
Sorry for the double post
Hey, that's impressing. Have you checked power dissipation, mosfet cascoding is known for very high voltage drops, but it should sound amazing.
Have you actually built one? Does it sound good?
Have you actually built one? Does it sound good?
Because you use lateral's you could try to remove 2N2222A.Also 4,7uf parallel on 470uf is too much.
-try 1uf instead.
-R2-18K it seems too low.Try 100K for easy match of the impedance between amp and preamp or whatever you have.
-try 1uf instead.
-R2-18K it seems too low.Try 100K for easy match of the impedance between amp and preamp or whatever you have.
felixx said:
It does not matter if he use C6C9 to block the DC feedback or if he will use DC-Servo instead. The only one influence is thzt dc offset without C6C9 depend of the eqv. resistance symmetry at both OP inputs.
Usially, preamp that cannot work with 18k load - has no rights to live 🙂
I will try it soon, everything is carefully designed for the 2SK1058/2SJ162 or it will work with 2SK1530/2SJ201?
I see that you use 12 pF Cdom, but i only have 10 pF ones arround. Did you try it with 10 pF?
I see that you use 12 pF Cdom, but i only have 10 pF ones arround. Did you try it with 10 pF?
A 2pF difference should not have any major effect on the circuit, especially considering capacitor tolerances.
"The capacitor should be placed close to the LME49810 and a silver
mica type will give good performance. The value of the ca-
pacitor will affect slew rate and stability."
6..8pf no bad too, if you have good assembling.
Why no?
Slew rate skyrockets when capacitance is decreased below 10 pF since the relationship is not linear. Have you got 6-8 pF to work? Did you measure slew rate in these conditions?
I am once don’t soldered this capacitor. I don’t measured slew rate with 8pf. But sound don’t change.
Ivan -- you don't really need the Vbe multiplier if using the Renesas Lateral MOSFET's. See the application notes for the LM4702.
http://www.national.com/an/AN/AN-1645.pdf
You might want to wait for the LME49830 to go full production for MOSFETs. There are only samples trickling out of Nat Semi at the moment.
The LME49810 is for guitar and PA applications. The LM4702 is for high-end audio, the LM4702 will drive a pair of lateral mosfets without breaking a sweat.
http://www.national.com/an/AN/AN-1645.pdf
You might want to wait for the LME49830 to go full production for MOSFETs. There are only samples trickling out of Nat Semi at the moment.
The LME49810 is for guitar and PA applications. The LM4702 is for high-end audio, the LM4702 will drive a pair of lateral mosfets without breaking a sweat.
I have MOSFETS with namber of productions "7D4".
I don`t have LME4702. But this scheme for closed box (60lit) with speaker of broadband(100w 8r).
LME49830 of course best for MOSFETS. I know about datasheet
http://www.national.com/an/AN/AN-1645.pdf
But sheme
www.ivanaudiomaster.narod.ru/LME49810timbre.GIF
is the best of my construction. Preamplifer don't need with 1 pair SJ162/SK1058.
I don`t have LME4702. But this scheme for closed box (60lit) with speaker of broadband(100w 8r).
LME49830 of course best for MOSFETS. I know about datasheet
http://www.national.com/an/AN/AN-1645.pdf
But sheme
www.ivanaudiomaster.narod.ru/LME49810timbre.GIF
is the best of my construction. Preamplifer don't need with 1 pair SJ162/SK1058.
This is my acoustic system.
http://ivanaudiomaster.narod.ru/closedbox100gd60l.pdf
http://ivanaudiomaster.narod.ru/photoalbum100gd33.html
I'm sorry for my English.
http://ivanaudiomaster.narod.ru/closedbox100gd60l.pdf
http://ivanaudiomaster.narod.ru/photoalbum100gd33.html
I'm sorry for my English.
And the model this acoustic system(JBL SPEKERSHOP).
http://ivanaudiomaster.narod.ru/100GD60LITROV.pdf
I liked 'The model' Kraftwerk.
http://ivanaudiomaster.narod.ru/100GD60LITROV.pdf
I liked 'The model' Kraftwerk.