My pre is high frequency noise!
The voltage across this 1 ohm resistor V= 220V. i conect !
You se image
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He, he
You're telling me you got 220 amperes going through that resistor (and implicitly, through the mosfet)?!? No way, you're making a mistake in measuring.
WhatCan i do Now??
You have to measure it correctly. It cannot be 220V across the resistor. Remember that the source of Q3 is the third pin, G D S, as seen from the front.
One other way to measure the current through Q3 is to replace the 1 ohm resistor with the DMM set on the 200mA.
Do you have a 10W resistor between 4k7 and 6k8? If you do, I would suggest that you disconnect your preamp and connect this resistor as the load. Then measure everything again.
One other way to measure the current through Q3 is to replace the 1 ohm resistor with the DMM set on the 200mA.
Do you have a 10W resistor between 4k7 and 6k8? If you do, I would suggest that you disconnect your preamp and connect this resistor as the load. Then measure everything again.
This makes sense. I hope nothing happened, with him being so quiet all of a sudden.
Well, in short, this tube has more connections for cathode and grid. Make shure you use all or cut the pins of the unused connections right at the socket as these make beautiful HF antennas. Use grid stoppers and solder the resistors very close to the pin. 150V and 10mA are good op points, more current brings out the uneven harmonics.
- Q: How is the temperature of Q2?
Q2 : a little hot
Im mesure thi morning!
Thank all!
I measured parameters in drawing. it is noise
I think My pre is high frequency noise
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Your measurements on the shunt show it healthy. Good you use a little sink on the MPSA92. Did you turn the 100R trimmer to go a little higher on Vout? The 92 gives lower than the 350. Looks like your Leds - vgs is rather under target, use 33R for R1, so to have a little more spare current. From what I see you now run 57mA and your channels draw 40mA together. Don't leave the 1R test there, its bad for normal use.
Follow Disco's recommendations on debugging your preamp. Nice PCB.
P.S. You mean you have ''hisss'' noise? Can we see the circuit of your preamp?
Follow Disco's recommendations on debugging your preamp. Nice PCB.
P.S. You mean you have ''hisss'' noise? Can we see the circuit of your preamp?
Ok! I think The Shunt is good, the sound is very best! I like Salas shunt!
I sure my pre use tub 6c45, is not good, i check again!
I measure 3 Leds = *betwen C1 // 3 leds*. V= 5.8 v!, i think is ok??
thank!
Quang Hao
Yes, healthy. It is just that the CCS current depends on a relationship between Leds, IRFP9240 Vgs, so we start with safe resistors not to run too hot. Looks like you are having about 3.7V Vgs and your transformer sags a little under constant current. Yor shunt is adequate. Look in the preamp. Hiss noise some times is too much bias in high gain tubes when not safeguarded perfectly for oscillation. They can only optimally used to run much current many times. How many mA you run into each? I see 20 + 20 mA supply draw in the shunt, try 10mA each. Then the 840 sink will go hotter, you can go back to a higher resistor like 47R if you stay in 10mA bias for 6C45Π.
Also see http://www.diyaudio.com/forums/showthread.php?p=294728
Also see http://www.diyaudio.com/forums/showthread.php?p=294728
How many mA you run into each? I see 20 + 20 mA supply draw in the shunt, try 10mA each. Then the 840 sink will go hotter, you can go back to a higher resistor like 47R if you stay in 10mA bias for 6C45Π.
No! i want bias for 6c45Pi 15-17ma one tube!, i thik it is good sound than 10ma one tube!
Then the 840 sink will go hotter, Yes ! it is hotter ! i use R1= 33R!
! thank
No! i want bias for 6c45Pi 15-17ma one tube!, i thik it is good sound than 10ma one tube!
Then the 840 sink will go hotter, Yes ! it is hotter ! i use R1= 33R!
! thank
It is still ees..ee! I think Tube 6c45.
Shunt is good! I try to treatment miller for tube 6c45pi!