STK4050V, for real!
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?
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?
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???
Nice to see someone still "in love" with Sanyo's STKs.:)
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
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.)
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 :dead: )...
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... :devilr:
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
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