Greetings,
At the moment, I'm working on a STK4050V power amplifier, and I've been browsing STK40xx related posts on this forum to get some info. I found some very useful informations, but still, there are a few questions...
Q-1. Thermal shutdown
Q-2. Load-short protection circuit
Q-3. Pop noise muting
The datasheet says that the amp supports addition of these electronic circuits. Are these circuits already in the schematics, or if not, does anyone have the schematics?
Q-4. Input signal voltage and impendance
Does anyone know the maximum input signal voltage in Vrms and nominal input impendance?
Q-5. PSU with voltage regulation
Can I use a PSU with positive/negatve float voltage regulators? is there anything bad about this idea? Resonances? Cooling problems?
Q-6. R15?
There is a Sanyo datasheet,
And also schematics I've found on this forum (attached);
There is one question- what is the purpose of the 100 ohm resitor R15? There is no such resistor in Sanyo datasheet...
Q-7. Stopping oscillations
rljones posted: this;
Should I change the input resistors from 1K/56K to 1K/20K, and why exactly? Where should I put that 200pF cap- between ground and which point in the schematics?
Q-8. Speaker impendance
What happens if a 4ohm speaker is connected? If I got it right, output resistors and PSU must be able to handle 2x the nominal current, right? And then the STK will burn out if it feels like it... And what happens if a 16 ohm speaker is connected? Evrerything should be OK, right?
Q-9. Part list
Considering the schematics and common sense, I have made this part list. Could someone be so kind to check the voltage and power ratings for the components?
At the moment, I'm working on a STK4050V power amplifier, and I've been browsing STK40xx related posts on this forum to get some info. I found some very useful informations, but still, there are a few questions...
Q-1. Thermal shutdown
Q-2. Load-short protection circuit
Q-3. Pop noise muting
The datasheet says that the amp supports addition of these electronic circuits. Are these circuits already in the schematics, or if not, does anyone have the schematics?
Q-4. Input signal voltage and impendance
Does anyone know the maximum input signal voltage in Vrms and nominal input impendance?
Q-5. PSU with voltage regulation
Can I use a PSU with positive/negatve float voltage regulators? is there anything bad about this idea? Resonances? Cooling problems?
Q-6. R15?
There is a Sanyo datasheet,
And also schematics I've found on this forum (attached);
There is one question- what is the purpose of the 100 ohm resitor R15? There is no such resistor in Sanyo datasheet...
Q-7. Stopping oscillations
rljones posted: this;
Should I change the input resistors from 1K/56K to 1K/20K, and why exactly? Where should I put that 200pF cap- between ground and which point in the schematics?
Q-8. Speaker impendance
What happens if a 4ohm speaker is connected? If I got it right, output resistors and PSU must be able to handle 2x the nominal current, right? And then the STK will burn out if it feels like it... And what happens if a 16 ohm speaker is connected? Evrerything should be OK, right?
Q-9. Part list
Considering the schematics and common sense, I have made this part list. Could someone be so kind to check the voltage and power ratings for the components?
R1 1K 2W 5% carbon film
R2 56K 2W 5% carbon film
R3 560 0.5W <1% metal film !
R4 10K 2W 5% carbon film
R5 56K >2W <1% metal film !
R6 100 2W 5% carbon film
R7 1K 2W 5% carbon film
R8 100 2W 5% carbon film
R9 .22 5W 5% ceramic
R10 .22 5W 5% ceramic
R11 .22 5W 5% ceramic
R12 .22 5W 5% ceramic
R13 4.7 5W 5% ceramic
R14 4.7 5W 5% ceramic
R15 100 0.5W lin trimmer
C1 470p 500V ceramic
C2 4.7u 160V electrolytic
C3 100u 160V electrolytic
C4 10u 160V electrolytic
C5 100u 160V electrolytic
C6 100p 500V ceramic
C7 1n 500V ceramic
C8 100u 160V electrolytic
C9 100p 500V ceramic !
C10 100p 500V ceramic !
C11 10u 160V electrolytic
C12 1u 350V electrolytic
C13 0.1u 400V polyester film
Attachments
A-Parts list
Over kill on your cap voltage!!!!
C1, C2, C3 are all low voltage stuff like 1~2V so 10V caps are good for that and will save you some money and space.
C4, C5, C8, C11, C12 are way too high, suggested value on schematic is 63V which is way more than enough.
C6, C7 50V should be more than enough.
C9 and C10 should be double so if using a 50V rail, use 100V caps
C13 should be what is shown on schematic, 120V
Resister wqattages are way too high!!!!!
R9, R10, R11, R12 are good, leave them at 5W
R1, R2, R3, R4, R7, R15 could be 1/8W but 1/4 are easier too handle.
R6 and R8 are 1/2W as listed in schematic.
R5, R13, R14 are 2W, agin as listed in schematic.
Input voltage as stated above is about 1~2V max and Input imp. would be fairly high which is good.
Q-1,2,3 can all be done with on IC like the HA12001 (which is out dataed but good for examples) which can disconnect the load if the amp gets too warm (load = HEAT). It can also (because it uses a relay for load disconect) remove the load incase of amp shorting or disconnect load if load shorts. It also has a delayed on and almost instant off so pop noise is unheard of.
Sanyo recomends a 8 Ohm load so I wouldn't attemt any lower unless you want to lose a STK. High ohm speaker is easier for amp to drive but going from 8-16ohm will cut output power(W) in half.
Don't worry about Q-7 until you have built the amp then you can check for oscillation and fix it then.
Having a regulated PSU will not yeild a hole lot of inprovments for all the work and space that would be required.
BTW I have no Idea what R15 is for exactly, looks like a snubber network across pins 7 and 10? anyone want to correct or verify?
Over kill on your cap voltage!!!!
C1, C2, C3 are all low voltage stuff like 1~2V so 10V caps are good for that and will save you some money and space.
C4, C5, C8, C11, C12 are way too high, suggested value on schematic is 63V which is way more than enough.
C6, C7 50V should be more than enough.
C9 and C10 should be double so if using a 50V rail, use 100V caps
C13 should be what is shown on schematic, 120V
Resister wqattages are way too high!!!!!
R9, R10, R11, R12 are good, leave them at 5W
R1, R2, R3, R4, R7, R15 could be 1/8W but 1/4 are easier too handle.
R6 and R8 are 1/2W as listed in schematic.
R5, R13, R14 are 2W, agin as listed in schematic.
Input voltage as stated above is about 1~2V max and Input imp. would be fairly high which is good.
Q-1,2,3 can all be done with on IC like the HA12001 (which is out dataed but good for examples) which can disconnect the load if the amp gets too warm (load = HEAT). It can also (because it uses a relay for load disconect) remove the load incase of amp shorting or disconnect load if load shorts. It also has a delayed on and almost instant off so pop noise is unheard of.
Sanyo recomends a 8 Ohm load so I wouldn't attemt any lower unless you want to lose a STK. High ohm speaker is easier for amp to drive but going from 8-16ohm will cut output power(W) in half.
Don't worry about Q-7 until you have built the amp then you can check for oscillation and fix it then.
Having a regulated PSU will not yeild a hole lot of inprovments for all the work and space that would be required.
BTW I have no Idea what R15 is for exactly, looks like a snubber network across pins 7 and 10? anyone want to correct or verify?
Possible oscillation problems in the near future...
Thank you for the info!
If I got it right, the IC HA12001 solves the problems of overheating, short protection and pop noise? I didn't mannage to find the datasheet, nor a single thread on this forum... Are there any better solutions? Any links?
Regulated PSU is not worth the effort? Is the float voltage regulator too bad? I guess that 10000-50000 uF cap will be enough?
Does anyone else know the purpose of R15? I'll put a 100 ohm/0.25 W trimmer and see what happens...
I'm working on a PCB at the moment, and I do things nice 'n' tidy; so I'd like to know where should I put that cap if it turns out that I will be needing it. And what about that input resistors???
Thanks...
Thank you for the info!
If I got it right, the IC HA12001 solves the problems of overheating, short protection and pop noise? I didn't mannage to find the datasheet, nor a single thread on this forum... Are there any better solutions? Any links?
Regulated PSU is not worth the effort? Is the float voltage regulator too bad? I guess that 10000-50000 uF cap will be enough?
Does anyone else know the purpose of R15? I'll put a 100 ohm/0.25 W trimmer and see what happens...
I'm working on a PCB at the moment, and I do things nice 'n' tidy; so I'd like to know where should I put that cap if it turns out that I will be needing it. And what about that input resistors???
Thanks...
Are these old chips any good and how do they compare to newer stuff? I happen ta have 8pc of STK050 in my partsbin and it would be nice to know if they are useful for anything.
Good enough
As a well-informed n00b, I think they are. Anything bad about 200 Wrms @ 8 ohms w/ RMS ~ 0.08% and 28 passive external parts? They are easy to build, easy to bridge, and need no extra tinkering, save for a tiny oscillation problem (at VERY low levels, like 1 mW or so) that I mentioned...
Newer stuff? What newer stuff? Am I missing something? Any better options for my 200 Wrms @ 8 ohms w/ THD <0.1% project than a STK4050V?
Take a look at this thread , especially rljones' posts...
C'MON GUYS, HELP ME OUT- AM I ASKING TOO MUCH?
-> WHERE TO PUT THAT 200 pF CAP ??? <-
I HAVE ONLY 10 DAYS LEFT OF MY SUMMER HOLIDAY TO FINISH THAT AMP!!!
kmj said:
As a well-informed n00b, I think they are. Anything bad about 200 Wrms @ 8 ohms w/ RMS ~ 0.08% and 28 passive external parts? They are easy to build, easy to bridge, and need no extra tinkering, save for a tiny oscillation problem (at VERY low levels, like 1 mW or so) that I mentioned...
Newer stuff? What newer stuff? Am I missing something? Any better options for my 200 Wrms @ 8 ohms w/ THD <0.1% project than a STK4050V?
Take a look at this thread , especially rljones' posts...
C'MON GUYS, HELP ME OUT- AM I ASKING TOO MUCH?
-> WHERE TO PUT THAT 200 pF CAP ??? <-
I HAVE ONLY 10 DAYS LEFT OF MY SUMMER HOLIDAY TO FINISH THAT AMP!!!
Re: Good enough
I believe this cap goes from the right side of R5 to ground(the side of the resistor that goes to R9), thats the impression I get from the post you linkined in your first post.
BTW these stk amps sound just fine to me, the main problem is people either thinking these sound bad, heared it in a crappy design or are massive audiofies.
Oh and a newer up to date amp could be the TDA7293 (100W 120V 4-8Ohm load with low THD.)
Usher said:
I believe this cap goes from the right side of R5 to ground(the side of the resistor that goes to R9), thats the impression I get from the post you linkined in your first post.
BTW these stk amps sound just fine to me, the main problem is people either thinking these sound bad, heared it in a crappy design or are massive audiofies.
Oh and a newer up to date amp could be the TDA7293 (100W 120V 4-8Ohm load with low THD.)
Thanks
Thank you, you have been very helpfull! I got the same impression, I just wanted to chek...
A guy who owns a tiny music shop here in Belgrade, built a STK4048XI. We have compared it with Rowland 112 (if my memory serves me), with the same studio monitors, same mixer, same CD and same guitar. The two seemed pretty much the same to me, save for a bit smudgy-smeared basses (somewhere around 50Hz or so) on STK4048XI. BTW, this guy frowned on some harsh highs, but I wasn't able to tell the difference (I think I have a problem with highs
)...
TDA7293 is a real beauty, but I need more power... STK4050V is the most powerfull single-chip amp that I know of... BTW, I'm building a bass guitar gig-amp, and since I play in a heavy metal band, the STK4050V is more than "fine" to me...
ifrythings said:
Thank you, you have been very helpfull! I got the same impression, I just wanted to chek...
A guy who owns a tiny music shop here in Belgrade, built a STK4048XI. We have compared it with Rowland 112 (if my memory serves me), with the same studio monitors, same mixer, same CD and same guitar. The two seemed pretty much the same to me, save for a bit smudgy-smeared basses (somewhere around 50Hz or so) on STK4048XI. BTW, this guy frowned on some harsh highs, but I wasn't able to tell the difference (I think I have a problem with highs
)...TDA7293 is a real beauty, but I need more power... STK4050V is the most powerfull single-chip amp that I know of... BTW, I'm building a bass guitar gig-amp, and since I play in a heavy metal band, the STK4050V is more than "fine" to me...
One STK4050V Warm
Anybody can help...
I'v built 2 modules based on STK4050V schematic published here. At Normal Room Listening Level.. 1 of the module getting warmer but the other module not even warm..
both modules are working fine... only a low hum when no music. Powering up using +/- 53Vdc (from 36Vac Transfo 100VA).
Any suggestion guys.....TQ
Anybody can help...
I'v built 2 modules based on STK4050V schematic published here. At Normal Room Listening Level.. 1 of the module getting warmer but the other module not even warm..
both modules are working fine... only a low hum when no music. Powering up using +/- 53Vdc (from 36Vac Transfo 100VA).
Any suggestion guys.....TQ
STK chips are bad a$$. 😀 Like a full-size amp in a small package! I also like the fact they have NO current limit, and they have strong, clean sound.
I've played with STK 4231 100W/ch and 4221 80w/ch
(same pinout of both chips)
I have driven 4 ohm loads on the 8 ohm channels before 😱, and they drive quite well despite the overload. They also sound powerful with headroom and I've even fried small speakers with them! Highly recommended for a small high powered amp!!
I parallelled 2 channels of 4231 to drive a 4 ohm subwoofer @ 200WRMS before and it performed great! When I blew up the 4231 and switched to a 4221(all I had to replace with), it still holds up fine at 200W, despite running the chip past its spec. I still have that amp as a spare.
I've played with STK 4231 100W/ch and 4221 80w/ch
(same pinout of both chips)
I have driven 4 ohm loads on the 8 ohm channels before 😱, and they drive quite well despite the overload. They also sound powerful with headroom and I've even fried small speakers with them! Highly recommended for a small high powered amp!!
I parallelled 2 channels of 4231 to drive a 4 ohm subwoofer @ 200WRMS before and it performed great! When I blew up the 4231 and switched to a 4221(all I had to replace with), it still holds up fine at 200W, despite running the chip past its spec. I still have that amp as a spare.
Re: One STK4050V Warm
Sounds like oscillation in one. If both channels are identical, they should be same temp. Make sure you have zobels and small caps to filter your power rails
satcure645 said:
Sounds like oscillation in one. If both channels are identical, they should be same temp. Make sure you have zobels and small caps to filter your power rails
STK AMP QUESTIONS
Hello all,
I would just like to ask the members a question about these stk modules. I have 4 ch of STK 4235MKII amps (pulled from a surround reciever)and would like to either bridge or parrallel to get better performance in a sub amp. I have no real need for 4x100 individual channels, but a bridged and maybe even a parallel amp would fit the bill better. I am just clueless of how these modules work, but I would guess by being 2ch chip that bridge mode would have to be done with 2ch of a chip in parallel then 2 chips bridged? Just taking a stab at this, and would love to be educated in the STK amps.
Thank you
Steve
Hello all,
I would just like to ask the members a question about these stk modules. I have 4 ch of STK 4235MKII amps (pulled from a surround reciever)and would like to either bridge or parrallel to get better performance in a sub amp. I have no real need for 4x100 individual channels, but a bridged and maybe even a parallel amp would fit the bill better. I am just clueless of how these modules work, but I would guess by being 2ch chip that bridge mode would have to be done with 2ch of a chip in parallel then 2 chips bridged? Just taking a stab at this, and would love to be educated in the STK amps.
Thank you
Steve
Re: Re: One STK4050V Warm
Thanks for the reply, will check on that..BTW I've read somewhere in the post to install 200pf cap on the circuit as a solution to the OSC.. can somebody highlight where's there correct place to install this cap. I will try that as part of the t/shooting stage.
TQ.
EWorkshop1708 said:
Thanks for the reply, will check on that..BTW I've read somewhere in the post to install 200pf cap on the circuit as a solution to the OSC.. can somebody highlight where's there correct place to install this cap. I will try that as part of the t/shooting stage.
TQ.
satcure645, i saw your first post, and I started typing a reply when, all of a sudden, my hard drive died. 
Please wait a day or two (I need to recover the data), I have answers and complete instructions for all of your questions! 😉
Please wait a day or two (I need to recover the data), I have answers and complete instructions for all of your questions! 😉
I'll be waiting.....Thanks Again...
BTW the Hum already gone as my amp input cable (going to the Mixer) is sitting on the Main Transfo which producing the Humming sound during the test-currently only heating problem which I believe due to oscillation..need to be solve.
Both module are identical and both connected to same power source (+- 56Vdc 100VA) with 20000 uF per rail/40000 uF for both.
BTW the Hum already gone as my amp input cable (going to the Mixer) is sitting on the Main Transfo which producing the Humming sound during the test-currently only heating problem which I believe due to oscillation..need to be solve.
Both module are identical and both connected to same power source (+- 56Vdc 100VA) with 20000 uF per rail/40000 uF for both.
To start.............
Put a 200pf cap on the input of each amp. It filters out high RF frequencies, so only the audio itself goes into the amp.
*Highly recommended for ANY AMP is to add a HV 0.1uf capacitor (bigger if you can) to the power supply rails closest to the amplifier. I'd recommend 0.2uf to 1uf or more if you can find them.
Keep all input signal wires AWAY from the transformer!!! Keep the transformer away from the chipamp too. No need to have the transformer "inducing" currents into wires it's not supposed to.
Put a 200pf cap on the input of each amp. It filters out high RF frequencies, so only the audio itself goes into the amp.
*Highly recommended for ANY AMP is to add a HV 0.1uf capacitor (bigger if you can) to the power supply rails closest to the amplifier. I'd recommend 0.2uf to 1uf or more if you can find them.
Keep all input signal wires AWAY from the transformer!!! Keep the transformer away from the chipamp too. No need to have the transformer "inducing" currents into wires it's not supposed to.
EWorkshop1708 said:
Can you provide the "solution" on the schematic i.e 200pf on the Input and HV caps at the supply rails show on schematic as to avoid any future mistake - TQ.
Currently using 100nf/100v at both neg rail to gnd and pos rail to gnd. Power Supply designed based on NMOS 350W (Quasi Complimentery - under Power Amp Under Development Section). Caps change to 20000uF per rail.
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