240 watts from stk4050v module will it cook?

[jimmy audio]

Thanks to all for the help and advice! So now the amp is in place and hooked up enough to test. Driven by my ipod with Rush 2112 cranking the 4050 module is if my math is correct 31 peak volts squared / 4 ohms for an output of 240.25 watts rms. The 4048xi 's are peaking at 41.2 volts into 16 ohms for an output of 105.06 watts rms. The meter is a Fluke true rms scopemeter. I am guessing that the 4050 wont last long at that output but my normal listening level is much lower,if i lock down the volume on my ipod to 28 volts rms (196 watts) will it live?? Anyone have any experience driving 4 ohm loads at levels not exceeding 200 watts with these chips?? The sound quality in the open air of the screen porch is excellent with clean crisp highs solid midrange and a tight low end.thanks again for all your advice!! WE ARE ROCKING NOW!!

[geraldfryjr]

RMS is .707 of the peak voltage.
28Vrms into 8 ohms = 98 watts rms.
You must be trying to say peak rms?
I am very glad to see your tests as I have always wondered if those chips could actualy put out that kind power.

Keep up the good work! jer

[AndrewT]

Measure the maximum voltage into four different resistive test loads.
16r0, 8r0, 4r0, 2r0.

Calculate the dBV for each loading.
Compare how much dBV falls for each incremental lowering of load resistance.
A really good amplifier will lose <=0.8dBV for a halving of test load.
A really bad amplifier will lose >=1.5dBV for a halving of test load.

If you cannot bring your self to test for maximum power into a 2r0 resistive load, then you should not be considering the much more severe loading of a 4ohm speaker.

If the 16r0 to 8r0 dBV is <=-0.7dBv then proceed with next test.
If the 8ro to 4r0 dBV is ~-1dBV then you should probably not test into 2r0.

[jimmy audio]

Thanks for your replies. As for testing my main concern is not cooking the 4050 chip, i do have a 1 khz 1volt signal injector but to test the sub amp suppose i need more like a 80-100hz signal i suppose this would be more accurate than capturing a peak music signal? I don'y have any resistive loads so the speaker will have to do. I think that volt amp reactance will screw up things but unsure how to calculate. the heat sink is pretty good and runs only slightly warm after an hour or so at 80% (approx.) also not sure how to test for dBV what calculations are needed?

[Ferchito]

Originally Posted by jimmy audio

I am guessing that the 4050 wont last long at that output but my normal listening level is much lower,if i lock down the volume on my ipod to 28 volts rms (196 watts) will it live?? Anyone have any experience driving 4 ohm loads at levels not exceeding 200 watts with these chips??

Hi Jimmy, is very complicated put a 4 ohms load with this supply levels, you have to know that STK4050 work as single amplifier but it have four output transistors, working as two pairs in parallel mode and recommended
load is 8 Ohms for continuous 200W rms at +/-66V, For less impedance loads the module will overhead also with large heatsink.

[dlk666]

Hey man, do you perhaps have a schematic for the power supply you used with the 4050? I want to build one but need to figure out what power supply to use

[jimmy audio]

sanyo has an excellent data sheet with a schematic for the power supply included.Just google stk4050

[dlk666]

Originally Posted by jimmy audio

sanyo has an excellent data sheet with a schematic for the power supply included.Just google stk4050

Thanks, ive seen that, but i dont know what the ratings of an MG250 transformer are, tried googling it and i cant find anything. Would a 55-0-55 transformer at 300va be fine for a single chhannel? I used 55-0-55 so that at full load there will be atleast +- 66v and unloaded there will be 77V

[AndrewT]

240W from a +-77Vdc unloaded PSU?

I get ~310W into 4r0 and 170W into 8r0 from a +-58.5Vdc unloaded supply using a 230:40+40Vac transformer.
I would expect much higher 8r0 power from 45, 50 and 55Vac transformers.

[dlk666]

Originally Posted by AndrewT

240W from a +-77Vdc unloaded PSU?

I get ~310W into 4r0 and 170W into 8r0 from a +-58.5Vdc unloaded supply using a 230:40+40Vac transformer.
I would expect much higher 8r0 power from 45, 50 and 55Vac transformers.

Can the STK 4050 handle a 4R0 load? on the datasheets ive looked at it doesnt say? Oh, and are you using any sort of soft start circuit or does it work fine without one?