stk4048 Question from newbie

[murat]

Hi I want to build this big guy and need some help:



1) For capacitors: I don't know what types and voltage values to use for each capacitor.

2) For resistors: I feel like some should be power resistors but which one how much?

3) I will use perforated board instead of PCB but I will instal the parts like shown in the circuit pattern. Anyting to be carefull?

4) I found this: will it work for my power supply?

Thanks a lot!!

Murat

http://www.allelectronics.com/cgi-bi...-46&type=store http://www.datadart.com/al/sanyo/STK4048XI.pdf

[CPX]

hellostk 4048 is a very powerfull chip amplifier...and it works at up to +-87 volts(not recomanded ise max +-75 volts) so you must use high voltage capacitors lets say 4700-10000 mf at 90-100 volts for the power suply.since they cost much you may use pairs of 50-63 volts capacitors....also for the ic use 63+...if posibile 100 volts..
you mai also need power rezistors i dont realy know what... try for starters 5-20 wats and see how it works...you mai use perforeted board but i dont recomand it....use pcb if possible ....
as for the rectifier the one you have chosen probable will blow at the first full power test ..use a 15 amp+ rectifier or a 25 amp + if you build stereo.also use a toroidal power transformer 400 VA 2*50 vca for stereo
Good luck....i havent build this myself ..let me know how it works

[Stuart Easson]

Hi,

The power supply voltage you decide on will determine the correct minimum voltage for the rectifier and capacitors. The DC voltage from a transformer is approx 1.4 times the AC voltage. If you end up with +/- 50v, you can use 63v capacitors no problems. I'd allow 10% over for safety and reliability, so don't try and use 50v caps with a 50v supply...The rectifiers need to be rated for at least twice the voltage you end up with, so again with +/-50v rails you'd need at least a 100v rectifier, and I'd go for 10 amps at least, given your target output 20+ amps would be better. 150

The only resistors that need to be 'high' power are in the output of the amp, and should be a few watts, 3 or 5 ceramic is quite normal. Looking at the datasheet you would use these as the 0.22ohm resistors coming from pins 13, 16, 17 and 18, and for the 4.7ohm resistor in the output. The output inductor is perhaps 15 turns of heavy copper wire wound around the body of the resistor.

With +/-70v rails, you will get the 150w RMS into 8ohms, but to do this for 'real' for more than a few seconds will need a number of pretty big components, at a minimum, a very big heatsink (better than 0.2c/watt), a big transfomer (50-0-70, 450va), big caps (15000uF, 80v), all of this per channel. You can skimp on the caps for instance, but too small a heatsink and the module will die, too small a transformer and it will die, too small a rectifier and it will die, probably taking the caps and module with it...and this is only into 8 ohms, doing more into 4 ohms needs more hardware...

I constructed using the 4040xi module, it is a great amp, though I only use it for a sub now.

Have fun building it...

Stuart

[murat]

Thanks for your replies.

So, this is getting little bit expensive and bulky to me!!

The reason I wanted to build a powerfull amp was actually NOT since I needed this much power. I thought a powerfull amp would work more linearly at moderate volume levels hence better sound???

But now I also found something much affordable and convenient to build. Have you heard that Brian GT amp:

I think it is also powerful. If bridged, it should be 120 W per amp. Do you know whether its sound quality would be similar to a good STK like 4048XI??

Thanks again

Murat

Brian amp

[Stuart Easson]

Hi Murat,

Brians amp is a well known piece of equipment and has a good reputation for sound quality. It will give more power if bridged, but will only do so into a high impedance load (>8ohm), the 2 amps each see half the impedance of the load, so the result might not be as strong as you think into a normal speaker. The NatSemi approved solution for more power includes 4 or even 6 amps, paralleled and bridged.

The STK modules have a broad range of output powers and are quite easy to use, I haven't compared the results of my STK amp to a gainclone, basically because I'm still building it.

If you compare the hardware required to build amps of similar outputs you won't save much if anything by building a gainclone over using one of the STK modules. One big difference, Brians kit makes the gainclone technically easy, you simply assemble it, the STK module requires more design effort.

You probably need to decide how much power you actually need then plan accordingly. The gainclones are not 100w amps, if you can get away with 50ish watts, the gainclone is the way to go. The STK modules are available at much larger outputs, but any amp of this output level requires a bigger investment in hardware.

Stuart

[murat]

Dear Stuart,

Thanks one more. Now I found P101!!

Although not cheaper than a 4048 project I hope the sound quality may worth. Also I belive I will find more technical support for P101 compared to 4048 and also a ready PCB which I think I cannot make at home!

Still thinking and searching.

Murat

[HIPCHECK]

hey murat i live in arkansas and have alot of 4048 spare parts
1. stk4048 chips (2)
2. power supply (HUGE/and mounted on pcb)
3. bridge rectifier (mounted on heatsink)
4. power suplly caps (80v/10000uf)
5. (2) Huge heatsinks (really sexy alum with deep fins)
6. various other parts scrapped from pcb and also a zip file of pcb

im sure the caps,rectifier,psu etc works, chips well maybe? i had this old sunsui amp running my video game system forever it had blown many of cheap speakers in its days, tons of power.im not sure what version of the 4048 chips i have but can dig them up for you.

[murat]

Hey, thanks a lot for the info!

I have been searching about diy amp's for a while and I just ordered Leach low TIM amp PCB's.

May be to much for a newbie.

But still I feel little bit uncomfortable since I made the decision reading others opinions but without listening any of the amps!! I simply don't have such a chance.

Is it reasonable to ask sound differences between chipamps and solid states?

[PA0SU]

Gentlemen,

Forgive me when I am on the wrong thread but:

How do the Sanyo STK's (086G, 4048, and 4050) sound?
The promissed low distortion is not the only criterium, I think...

[PA0SU]

Is this thread dead?
Is there anybody who can tell me about the audio quality from the STK's ?