Hi artosalo!
What do you think is the better preamp?!
Please all be documented, since this schematic is for your guitar preamplifier !??
Regards and cheers!
P.S.
Recommendation: Make this preamplifier and enjoy in the Valve's/Tube's excellent sound - checked !!!
What do you think is the better preamp?!
Please all be documented, since this schematic is for your guitar preamplifier !??
Regards and cheers!
P.S.
Recommendation: Make this preamplifier and enjoy in the Valve's/Tube's excellent sound - checked !!!
Last edited:
Sorry. I don't understad what you are asking.
No, this is for HiFi-use.
I know almost nothing about guitar amplifiers.
artosalo, how about diode from 1st tubes anode to 2nd tubes cathode,as well as 1k resistor for grid?
1 k grid stopper at the grid of cathode follower is a good idea, but I don't see any reason to use the diode you mentioned.
Hi artasalo, in your schema can I use double triode like the russian 6N9S (6SL7 equivalent) without modification?
thanks...
thanks...
No.
You could use 6N8S without modification, but 6N9S is hi-mu triode with lower anode current and higher impedance levels.
Below is modified schematic for 6N9S. It may require some fine tune to be optimal, but for sure it works with component values shown.
An externally hosted image should be here but it was not working when we last tested it.
Constant Current Draw. If you remove the 47K and you have the same value resistors on both the anode load of the first and the cathode of second stage, the 1st and 2nd stages draw the same cureent, but in opposite phase, cancelling more noise and distortion.
you cad to both! then you d need 2 ccs! start with the CCDA, 10x easier to design! Only thing you take care is the the anode of the first stage is 1/2 the B+ voltage!
I don't follow your idea completely.
The anode resistor of 1st triode is equal to cathode resistor of 2nd triode. OK.
But there are resistors at the cathode of the 1st triode,
which determine the bias and the gain of the whole stage.
Thus the current of both halves is not equal.
Can you draw a schematic to clarify your idea ?
Concerning the distortion cancelling; in theory it works but in practise, two intentionally non-linear stages connected in series makes the final result worse than two linear stages in series. 2nd and maybe 3rd harmonic can be reduced in some circumstances but higer order harmonics will be increased.
Noise is random in nature and can not be cancelled ( by adding it to "inverted noise").
The anode resistor of 1st triode is equal to cathode resistor of 2nd triode. OK.
But there are resistors at the cathode of the 1st triode,
which determine the bias and the gain of the whole stage.
Thus the current of both halves is not equal.
Can you draw a schematic to clarify your idea ?
Concerning the distortion cancelling; in theory it works but in practise, two intentionally non-linear stages connected in series makes the final result worse than two linear stages in series. 2nd and maybe 3rd harmonic can be reduced in some circumstances but higer order harmonics will be increased.
Noise is random in nature and can not be cancelled ( by adding it to "inverted noise").
CCS can be used at the cathode follower, but not at the anode of the 1st triode.
The reason is that the anode resistor and the cathode resistor of 1st triode form the local feedback network that determines the gain of the stage.
If the anode resistor is replaced with CCS, then the gain "jumps" to near mu (=high)
and the NFB disappears and the design concept is lost.
Hi all !!
The solution is the sum of well-stabilized DC-voltage anode Ua=300V and the well-stabilized DC-voltage to the heating Uf=2x6,3V.
The question is what if the other Valve/Tube preamplifier second harmonic no distortion (out at 1.5 V) of 0.5 ... 0.8%?!
If you do not distortion design with transistors!!?
Regards !
The solution is the sum of well-stabilized DC-voltage anode Ua=300V and the well-stabilized DC-voltage to the heating Uf=2x6,3V.
The question is what if the other Valve/Tube preamplifier second harmonic no distortion (out at 1.5 V) of 0.5 ... 0.8%?!
If you do not distortion design with transistors!!?
Regards !
Last edited:
Might as well stick to the design and have the supply regulated....BTW, can I go down to 250dc regulated supply?
Well,when tubes are "cold", it should prevent second tube's grid from "seeing" almost full battery?
I see your point.
Anyhow there will be high voltage for a moment but not essential current.
So why not if one sees it necessary.
The idea is to keep the AC currents equal, not the DC currents. If the AC currents are equal (but opposite) then there is negligible modulation of the HT voltage, so you get a cleaner power supply.
Until the grid arcs to the cathode... That's what the diode prevents.
Last edited:
- Status
- Not open for further replies.