Hi
Original schematic use Toshiba two pair's 2SC5200&2SA1943 output transistor.I want too use TWO pair's of IRFP240&9240.
I am not sure in value of R23 and R24.Voltage on this two resistor schoud be 7.8V.This is OK,but what is with currrnet in two resistor's?
Explanation please....
Original schematic use Toshiba two pair's 2SC5200&2SA1943 output transistor.I want too use TWO pair's of IRFP240&9240.
I am not sure in value of R23 and R24.Voltage on this two resistor schoud be 7.8V.This is OK,but what is with currrnet in two resistor's?
Explanation please....
Attachments
Hi VICTOR!
Replace R23 and R24 with one resistor 390 Ohms and set 20mA trough Q11 and Q12.
MY proposition:
1. make the amplifier but don`t connect output mosfets
2. Replace R23 and R24 with one resistor 390 Ohms
3. try to adjust bias with R19 and see if you can adjust 20mA trough Q11 and Q12, and if you can`t , replace R18 with some other value to acheve this.
POZDRAV!
Replace R23 and R24 with one resistor 390 Ohms and set 20mA trough Q11 and Q12.
MY proposition:
1. make the amplifier but don`t connect output mosfets
2. Replace R23 and R24 with one resistor 390 Ohms
3. try to adjust bias with R19 and see if you can adjust 20mA trough Q11 and Q12, and if you can`t , replace R18 with some other value to acheve this.
POZDRAV!
Hi,
if you decide to go with FETs then add a gate resistor to each FET and add a zener from each gate to source.
Increase the output FET Iq to 100mA for each FET and allow your sink size to let you experiment with upto Iq=250mA per FET. This will get hot.
Move the base connection of Q8 to next to R18 and connect the wiper of VR19 back to R20.
if you decide to go with FETs then add a gate resistor to each FET and add a zener from each gate to source.
Increase the output FET Iq to 100mA for each FET and allow your sink size to let you experiment with upto Iq=250mA per FET. This will get hot.
Move the base connection of Q8 to next to R18 and connect the wiper of VR19 back to R20.
!
MikeB,Techo is very very good and stable amplifier."Mlaen" had built Techno and he had problem's with him because he mistake too much.Mlaen has change some transistor's(they are not used in original schematic) and because that he had problem's with Techno.His Techno now work's fine because boraomega saw were is "MLAEN" mistake.
In my country,one guy has built Techno two month's ago are his amplifier work's perfect.
MikeB said:
MikeB,Techo is very very good and stable amplifier."Mlaen" had built Techno and he had problem's with him because he mistake too much.Mlaen has change some transistor's(they are not used in original schematic) and because that he had problem's with Techno.His Techno now work's fine because boraomega saw were is "MLAEN" mistake.
In my country,one guy has built Techno two month's ago are his amplifier work's perfect.
That's quite ridiculous... A single 10pf millercap in a high gain amp is not much. Mlaen did only substitute the output stage with even slower transistors...
And, i don't know which one is better... I did not intend to measure sizes now, maybe you want ? You say boraomega's amps are better, have you compared ? If not,
Mike...
And, i don't know which one is better... I did not intend to measure sizes now, maybe you want ? You say boraomega's amps are better, have you compared ? If not,
Mike...
Why the need for insults?
The Techno is a pretty regular execution of a classic design. I would probably add more compensation in the VAS area, 33pf on both transistors from C-B. I would also change the VBE multiplier's pot connections - if the wiper were to fail, Bad Things would happen!
As MikeB says, the gain is rather high. I would probably change that to 22K. It is probably fine with a carefully laid out PCB however.
The Techno is a pretty regular execution of a classic design. I would probably add more compensation in the VAS area, 33pf on both transistors from C-B. I would also change the VBE multiplier's pot connections - if the wiper were to fail, Bad Things would happen!
As MikeB says, the gain is rather high. I would probably change that to 22K. It is probably fine with a carefully laid out PCB however.
!
MikeB,Mlaen has acknowledge that he mistake and that he is guilty person.
Mike,you desgigned only couple of amplifier while boraomega designed about 50 and maybe more schematics!You
he he he he
MikeB said:That's quite ridiculous... A single 10pf millercap in a high gain amp is not much. Mlaen did only substitute the output stage with even slower transistors...
And, i don't know which one is better... I did not intend to measure sizes now, maybe you want ? You say boraomega's amps are better, have you compared ? If not,
Mike...
MikeB,Mlaen has acknowledge that he mistake and that he is guilty person.
Mike,you desgigned only couple of amplifier while boraomega designed about 50 and maybe more schematics!You
he he he he
Hi viktor1986,
MikeB and jaycee both have a lot of experience. They are commenting in an effort to answer questions. This is to help you and steer you away from trouble. Listen to ilimzn and AndrewT carefully as well.
If you need to attack members and amplifiers then just contact Boraomega for help. Otherwise take bogdan_borko's advice:
-Chris
MikeB and jaycee both have a lot of experience. They are commenting in an effort to answer questions. This is to help you and steer you away from trouble. Listen to ilimzn and AndrewT carefully as well.
If you need to attack members and amplifiers then just contact Boraomega for help. Otherwise take bogdan_borko's advice:
-Chris
Re: !
Oh, things getting childish... I believe in quality instead of quantity...
What exactly was Mlaens mistake ? He never told. I only know that adding the missing inputfilter stopped it from oscillating.
Mike
viktor1986 said:
MikeB,Mlaen has acknowledge that he mistake and that he is guilty person.
Mike,you desgigned only couple of amplifier while boraomega designed about 50 and maybe more schematics!You
he he he he
Oh, things getting childish... I believe in quality instead of quantity...
What exactly was Mlaens mistake ? He never told. I only know that adding the missing inputfilter stopped it from oscillating.
Mike
I would go with this second schematic. In fact, it seems familar, im pretty sure it's someone from this board that posted it.
Personally I would use 2N5401/5551 in VAS and current mirror and then drive the MOSFETS with driver transistors but I'm not familiar enough with MOSFETS to know if this would bring any major advantage. Certainly for 5.1 use it is good enough.
Personally I would use 2N5401/5551 in VAS and current mirror and then drive the MOSFETS with driver transistors but I'm not familiar enough with MOSFETS to know if this would bring any major advantage. Certainly for 5.1 use it is good enough.
Re: !
If this amp is intended for subwoofer only, i would also build it without drivers, but for higher frequencies the vas get difficulties to drive the gatecharges of the irfp's. You have 2 possibilities here, increase the vas current (this will need more powerful/expensive transistors in vas), or add a simple driverstage (which will be less expensive).
I think Bora's choice of the 2n5551/5401 is very good, these transistors make good audio amplifiers.
Why do you want to use the IRFPs ?
Mike
viktor1986 said:
If this amp is intended for subwoofer only, i would also build it without drivers, but for higher frequencies the vas get difficulties to drive the gatecharges of the irfp's. You have 2 possibilities here, increase the vas current (this will need more powerful/expensive transistors in vas), or add a simple driverstage (which will be less expensive).
I think Bora's choice of the 2n5551/5401 is very good, these transistors make good audio amplifiers.
Why do you want to use the IRFPs ?
Mike
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