The 1M resistor isn't connected to ground. Its purpose is to feed current from the joint of the two 10k trimmers to the input for offset nulling at the output. The 1uF cap filters out contaminants(if present) to ground.
Of course. If your preamp has no offset, you can remove-it to improve the sound definition. or use a film cap.
Yup it is a "DC blocking cap". Plus the value is high enough so that there is no bass loss. And as Esperado says, use a high quality film cap here. Mine however has a cheap nonpolar electrolytic.
Hm... I have some high quality film cap, but I don't remembering having such high value. I have tons of 1uF film cap though, but I think not enough for this purpose 😕
If i'm not wrong, its a bit rare to have these high value film cap, isn't it ?😉
Bundle ten of them like dynamite sticks and join the fusewires at both ends. There you got a big and powerful 10uF dynamite... err... no, capacitor.
Or 2x 22uF in series, back to back. BTW, NP/BP is not always better than ordinary one. Just try any quality cap.
Quite a waste to use them like that ^^ better buy a big one to use 😀
Also waste of spaces, lining them like a choo-choo-train.
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NP=Non-Polar. BP=Bi-Polar.
Putting 2 polarized elcos make them like NP or BP.
2x22uF makes 11uF.
Can be positive to positive, or negative to negative. I don't know which arrangements suit which situations. But both can be done just like choosing NP or BP
Putting 2 polarized elcos make them like NP or BP.
2x22uF makes 11uF.
Can be positive to positive, or negative to negative. I don't know which arrangements suit which situations. But both can be done just like choosing NP or BP
Hi, I have insert the input filter, as close to base as possible. But the slight buzzing nosie I mention earlier still exist, maybe due to lack of shielding. (it is naked PCB ^^ no casing so far)
But what I notice is that the idle current of all my BJT is lower, maybe due to elimination of inaudible oscillation. 10mA of VAS became lesser than 9mA most of the time, except VAS become very hot due to palying music loudly.
Anyway, casing for shielding should connect to safety earth or ground ? or use '1 ohm style' ?
You can decrease the 1k2 resistors in small steps to increase current through input and VAS transistors.
Small "U" shaped heatsinks will be good for VAS. Direct contact, no mica or other insulation.
Safety earth directly connected to casing. From there a 10ohm to signal ground.
Hehe, I have no problem with that, I could adjust the pot to adjust both sides idle current and output voltage.
But what I meant is this happen (reduction of current) without adjusting pot, I'm suggesting something happen in input line, such as reduction of HF noise.
Maybe I should put up my schematic later on after I make it nice ^^
hehe, I'm using small heatsink, but sufficiently cooled for me. The VAS doesn't goes very hot, but just makes idle current increase slightly.
Hm..... yeah, but if I doesn't remember wrongly, someone also suggest put cap parallelly to the 10 ohm.
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