If input 2sk170 is with high Idss R13 have high voltage drop and swing on R4 is not enough. I think that Buzzforb have this situation.
I can parallel 2sk170 with lower Idss and put lower sorse resistor and on that way gain is higher with corect voltage on R13. Maybe 2sk170GR is much better solution, like on MC stage at XONO
I can parallel 2sk170 with lower Idss and put lower sorse resistor and on that way gain is higher with corect voltage on R13. Maybe 2sk170GR is much better solution, like on MC stage at XONO
If you change B+ and nothing changes across R4 towards a 4V goal then something's done wrong in your build. Either a value or an orientation or you simply don't measure the right points. Measure directly across R4 to see.
IN creasing B+ did not change anything. Vdrop across R4 remains at 8v. I will try the BC560's
@ impuls
MC set for your 3*K170 is 3x10R Rs, R13 1.2K 2W, 34V on its top, about 6.5mA through each fet id 8.5mA samples, about 8.2V on Q3's emitter to ground, about 4.2V across R4.
P.S. Gain 60dB. On MM in a little.
MC set for your 3*K170 is 3x10R Rs, R13 1.2K 2W, 34V on its top, about 6.5mA through each fet id 8.5mA samples, about 8.2V on Q3's emitter to ground, about 4.2V across R4.
P.S. Gain 60dB. On MM in a little.
TP1 is top of Jfet. TP2 is top of 2.2K resistor.
Changing the BC did nothing. What is the better route for solving the issue?
Lowering Rs or Increasing R13. MAy not have a lot of options with R13. I beieve i have some 2.2K from an old build, but that would seem extreme. I have more B+ if needed, just didn't know if there is ceiling?
Changing the BC did nothing. What is the better route for solving the issue?
Lowering Rs or Increasing R13. MAy not have a lot of options with R13. I beieve i have some 2.2K from an old build, but that would seem extreme. I have more B+ if needed, just didn't know if there is ceiling?
If you had an FSP board you would have seen it marked. TP2 shows same voltage on any point from Q3's collector to C3's input junction.
You did not inform us on your R2, R3, R13 values and also check if you have a problem with VR1.
I am suing 2sk369
R2,3 are 3.9 and are dropping 33mV.
R13 is 1.2K, per the bild guide.
Vr1 is working
I built it up according to the newest build guide. the only changes i made are in the ouput buffer scetion. I dropped standard buffer and used a different option in order to lower coupling cap. Similar to what Rush did.
R2,3 are 3.9 and are dropping 33mV.
R13 is 1.2K, per the bild guide.
Vr1 is working
I built it up according to the newest build guide. the only changes i made are in the ouput buffer scetion. I dropped standard buffer and used a different option in order to lower coupling cap. Similar to what Rush did.
Thanks Salas, that`s what i need, voltage across Q3.
Buzzforb voltage on R13 is defined with LEDs reference voltage and B+. This voltage and resistance of R13 give current. If current through jfet-s is too small voltage on R4 will be too high. You must increase current jfet-s with smaller source resistor
Buzzforb voltage on R13 is defined with LEDs reference voltage and B+. This voltage and resistance of R13 give current. If current through jfet-s is too small voltage on R4 will be too high. You must increase current jfet-s with smaller source resistor
@ impuls
MM mode. Rs=3X150R (1.8mA per fet in example of 8.5mA idss fets), 3.3K 1W R13 (32.8V on its top), Q3 checks same, 56R R8, gain=45.5dB (good for EPC-P23).
Good luck.
MM mode. Rs=3X150R (1.8mA per fet in example of 8.5mA idss fets), 3.3K 1W R13 (32.8V on its top), Q3 checks same, 56R R8, gain=45.5dB (good for EPC-P23).
Good luck.
We need know R4's drop also. Move B+ or VR1 or together to see 24V across R13.
Hi folks
I am planning to connect the FSP integrated to a MUSES72320 http://www.akouo.at/akouo/downloads/volume-select-datasheet-en.pdf. The chip has an average input impedance of 20k and the Akouo boards have an additional possibility to tune eventual channel variance down to 10k. Normally they differ only a few percent though, so maybe 19k is realistic.
What opt cap size would you go for? 10k gives a -3dB @ 7,23Hz and 20k @ 3,62Hz with the speced 2,2 uF.
I am planning to connect the FSP integrated to a MUSES72320 http://www.akouo.at/akouo/downloads/volume-select-datasheet-en.pdf. The chip has an average input impedance of 20k and the Akouo boards have an additional possibility to tune eventual channel variance down to 10k. Normally they differ only a few percent though, so maybe 19k is realistic.
What opt cap size would you go for? 10k gives a -3dB @ 7,23Hz and 20k @ 3,62Hz with the speced 2,2 uF.
I have a 2.2uf Rike on the output of my MM FSP.
It is well detailed, and certainly a little more organic sounding.
Regarding resistors, I like the PTF65 and 55 Dale resistors. Not easy to get a lot of values, but I find that low ppm resistors sound better. They are not cheap, but they are less than any texas instrument product.