SheldonD,
To answer your questions.
1.I see little reason to keep 2 diodes in circuit
Don't populate D2 and D4 as shown in the PS schematic below.
2. there should be some decoupling capacitors although Ii think 4x4700 is huge overkill. It may be my suggested 2 x 1500ufd might not be enough.
If your external PS has plenty of reservoir capacitance, rule of thumb being 1000uF for every 10 watts of amplifier output power, then your choice of 2x1500uF is fine.
3. 0R2 resistors as input to decoupling caps would also aid in decoupling. so I would leave these in.
Just make sure the 0.2 resistor is rated for at least 3 watts.
Al
To answer your questions.
1.I see little reason to keep 2 diodes in circuit
Don't populate D2 and D4 as shown in the PS schematic below.
2. there should be some decoupling capacitors although Ii think 4x4700 is huge overkill. It may be my suggested 2 x 1500ufd might not be enough.
If your external PS has plenty of reservoir capacitance, rule of thumb being 1000uF for every 10 watts of amplifier output power, then your choice of 2x1500uF is fine.
3. 0R2 resistors as input to decoupling caps would also aid in decoupling. so I would leave these in.
Just make sure the 0.2 resistor is rated for at least 3 watts.
Al
Hi,
difficult to find some parts at a good price...
diodes hfa are 6$/p . (4,75€) here.
Can i use this ones from ST "Turbo 2 ultrafast hight voltage rectifier ST Microeletronics STTH12R06D/FP.
12A 600V 45ns in TO220AC (find in RS catalogue, in stock) price:1.5 $/p
About 2n5551, are finally BC550C better ?
Thanks.
jf
difficult to find some parts at a good price...
diodes hfa are 6$/p . (4,75€) here.
Can i use this ones from ST "Turbo 2 ultrafast hight voltage rectifier ST Microeletronics STTH12R06D/FP.
12A 600V 45ns in TO220AC (find in RS catalogue, in stock) price:1.5 $/p
About 2n5551, are finally BC550C better ?
Thanks.
jf
jef9200 said:
If you replace 2n5551 in vas (not q1/2) with bc550c, it will blow up because of overvoltage.
In input bc550c will work if supplyvoltage ist not higher than +/-36v.
Mike
Component change advice needed
Guys,
I'm using MPSA18 for the input pair and MPSA42/92 for all other small signal device. Is that OK?
Can I use Wima FKP2 (polypropylene) for C2 and C7 instead of Silver mica?
Driver and output stage are MJE15034/5 and MJL4302/3281. Is that OK?
Power supply from 37ac (150VA) EI transformer producing around +/-50V driving two channels.
Pls advice.
Thanks.
Guys,
I'm using MPSA18 for the input pair and MPSA42/92 for all other small signal device. Is that OK?
Can I use Wima FKP2 (polypropylene) for C2 and C7 instead of Silver mica?
Driver and output stage are MJE15034/5 and MJL4302/3281. Is that OK?
Power supply from 37ac (150VA) EI transformer producing around +/-50V driving two channels.
Pls advice.
Thanks.
Final schematics using MJL4302a/MJL4281A
Hi,
I've received boards from Ryssen and parts from mouser. Just wondering what is the final schematics using the above transistors with +/-50V dc power supply. It would be a great help for the fellow members if someone can publish the circuits using different output combinations for this PCB. I know the differences were posted in various threads but it would be handy if some one can consolidate those things and post in a single PDF file.
thanks,
routhun
Hi,
I've received boards from Ryssen and parts from mouser. Just wondering what is the final schematics using the above transistors with +/-50V dc power supply. It would be a great help for the fellow members if someone can publish the circuits using different output combinations for this PCB. I know the differences were posted in various threads but it would be handy if some one can consolidate those things and post in a single PDF file.
thanks,
routhun
Re: Component change advice needed
Hi, with +/-50v you must not use mpsa18, it has 45v rating. You can use mpsa42.
The Wima fkp2 are fine.
Outputdevices are fine, but, at +/-50v a single output pair becomes critical even when driving only 8ohms.
Symasym was designed for +/-36v, +/-40v at most.
yes, it's also a ClassAB amp!
But, you can not use 2n5550 for q14, it will overheat. BD140 for q4 is also not suitable, BD140 has max rating of 80v.
Without vas-protection, q13 will blow on excessive positive clipping...
You should consider basestoppers to the drivers, what is c7 for?
R2 should be directly behind c5, otherwise your input filter operation depends on output impedance of signal source.
Q3 will also overheat, so will Q1/2, are you sure you want to feed ~40ma into the input diffamp?
Why are r7/26 different?
Mike
Ipanema said:
Hi, with +/-50v you must not use mpsa18, it has 45v rating. You can use mpsa42.
The Wima fkp2 are fine.
Outputdevices are fine, but, at +/-50v a single output pair becomes critical even when driving only 8ohms.
Symasym was designed for +/-36v, +/-40v at most.
MJL21193 said:
yes, it's also a ClassAB amp!But, you can not use 2n5550 for q14, it will overheat. BD140 for q4 is also not suitable, BD140 has max rating of 80v.
Without vas-protection, q13 will blow on excessive positive clipping...
You should consider basestoppers to the drivers, what is c7 for?
R2 should be directly behind c5, otherwise your input filter operation depends on output impedance of signal source.
Q3 will also overheat, so will Q1/2, are you sure you want to feed ~40ma into the input diffamp?
Why are r7/26 different?
Mike
Mike,
if you manage to scrape together die kohle for a Wiesmann MF5 i'll gladly exchange the 5 liter Beamer engine for an oldy carburator 8-valve 1.9ltr Opel.
Much safer for you.
if you manage to scrape together die kohle for a Wiesmann MF5 i'll gladly exchange the 5 liter Beamer engine for an oldy carburator 8-valve 1.9ltr Opel.
Much safer for you.
MikeB,
Thanks for your advise. Is there anything wrong with my power supply? 37ac-0-37ac ==>rectifier==> +50V/-50V
which one will sound nicer? Silver mica or Polyproplene?
My batch of MPSA42 only have hfe of 100. Is that good enough? While my MPSA18 have hfe of 700. Which one will sound nicer in your opinion? I wouldn't mind to lower the power supply if it helps. 🙂
All the the pair transistor are hfe match but vbe is unmatch.
Thanks.
Thanks for your advise. Is there anything wrong with my power supply? 37ac-0-37ac ==>rectifier==> +50V/-50V
which one will sound nicer? Silver mica or Polyproplene?
My batch of MPSA42 only have hfe of 100. Is that good enough? While my MPSA18 have hfe of 700. Which one will sound nicer in your opinion? I wouldn't mind to lower the power supply if it helps. 🙂
All the the pair transistor are hfe match but vbe is unmatch.
Thanks.
When I used 2N5551 as input devices with hFE barely above 100 I got a nasty turn-on transient. I use BC550c now with much improved results, but then again my rails are only 37 to 38V (depending on line voltage).
Hi,
2n, mps are both cbe.
bc5xx are ecb.
2s & bc5xxL are bce.
A very few manufacturers differ from the standard pin out. Measure to be sure.
2n, mps are both cbe.
bc5xx are ecb.
2s & bc5xxL are bce.
A very few manufacturers differ from the standard pin out. Measure to be sure.
Andrew, you are wrong here. Yes, mps and 2n have the same pinout, cbe.
All bc have ebc, just mirrored.
2S/2C have bce.
All bc have ebc, just mirrored.
2S/2C have bce.
Ipanema said:
The problem with your supply are the 150va. That's not even enough for one channel at these voltages.
Consider at least 225va with 24vac giving 36vdc. (one for both channels)
Mike