The Soundstream 700s uses NDP7050 with 3.3ohm gate resistors.
The 7050 has a "Rds On: 13 mOhms" and they are 50v 75amp.
Can I use IRF3205PBF to replace them? Rds On: 8 mOhms, 55v 110amp.
Will the gate resistors work with them?
If not, I've got NDP7060 or 85N06 to use.
Thanks all.
The 7050 has a "Rds On: 13 mOhms" and they are 50v 75amp.
Can I use IRF3205PBF to replace them? Rds On: 8 mOhms, 55v 110amp.
Will the gate resistors work with them?
If not, I've got NDP7060 or 85N06 to use.
Thanks all.
PM wadest. He probably designed that amp.
My opinion, if you're rebuilding it to be original, I'd use the originals. If I was repairing it for an abusive user, I'd use the 3205s. Either will be reliable for the average user.
My opinion, if you're rebuilding it to be original, I'd use the originals. If I was repairing it for an abusive user, I'd use the 3205s. Either will be reliable for the average user.
The NDP7050's are hard to find. DIGI-KEY has them for $7.79 ea.
I plan on keeping it so is it OK to use the NDP7060's?
I plan on keeping it so is it OK to use the NDP7060's?
Well I saw this too late! I put NDP7060's in. It will be used for the front speakers so not that much current draw.
Thanks. 😀
Thanks. 😀
90scaraudio, Actually they will work fine. What i was goinng to recommend was fets that wre 60 volts or higher. Sometimes under heavy load the stray inductance of the transformer / Fet circuitry can cause spikes which can blow the fets. 60 volts is 4 times higher than than the 14.4 volts a typical alternator puts out.
wadest
How high can the voltage rating of the FETs be? Would these have worked? Now I'm curious 🙄
I've got a bin full.....
HUFA75645P3
75A, 100V, 0.014 Ohm, N-Channel,
UltraFET® Power MOSFETs
Also, can I PM you about a RUB1000-2
How high can the voltage rating of the FETs be? Would these have worked? Now I'm curious 🙄
I've got a bin full.....
HUFA75645P3
75A, 100V, 0.014 Ohm, N-Channel,
UltraFET® Power MOSFETs
Also, can I PM you about a RUB1000-2
The ringing/spikes are generally a sign that the transformer was poorly wound and isn't a significant problem in production amplifiers with professionally would transformers. The snubbers generally tame any ringing. Even if they occasionally reach the rated voltage of the FET, the intrinsic diode will clamp it.
90scaraudio, if you have a scope, look at the waveforms on the drains of the FETs. What is the highest voltage you see on the leading edge?
90scaraudio, if you have a scope, look at the waveforms on the drains of the FETs. What is the highest voltage you see on the leading edge?
I do have a scope, never thought of looking at that. Will that tell what voltage the MosFets should be? Or times four?
Thanks Perry.
Thanks Perry.
50-60v FETs will work in virtually any amp with a 12v supply voltage using the typical push-pull power supply design. Look at the waveforms. The top of the square wave on the drains is 2x the supply voltage. If there is ringing on the leading edge, it's typically just a few volts higher.
Look at the IRFZ44. It's used in some of the most poorly designed amps ever built (and in properly designed amps as well). Even in budget priced amps with marginal designs, the 55v Z44 is reliable.
You probably have multiple amps laying around. Power them up and drive them relatively hard (sometimes the ringing isn't an issue at idle). What is the maximum voltage spike that you see with any of your amplifiers?
Look at the IRFZ44. It's used in some of the most poorly designed amps ever built (and in properly designed amps as well). Even in budget priced amps with marginal designs, the 55v Z44 is reliable.
You probably have multiple amps laying around. Power them up and drive them relatively hard (sometimes the ringing isn't an issue at idle). What is the maximum voltage spike that you see with any of your amplifiers?
OK, I've not done this before. Do I take my probe lead to the drain and hook the shield lead to ground? This would make sense...
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90scaraudio, If you connect your scope between the drain of the mosfets and ground under full load you should see spikes on the square wave form. measure the voltage of that spike and that will the voltage from drain to source across the mosfet.
wadest
Under full load. 😱 Crap, don't have a 60 amp power supply or load, except my car!
This is what they look like at idle...
Shouldn't the PWM have a nice square wave?
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Not for amplifiers with regulation. The reduced duty cycle will give odd waveforms. Reduce the DC input voltage and the waveform will be more like what you expect.
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K, I don't think the Reference 700s is regulated. Do they look ok or should I change the PWM, 2N2222 and 2SA1562's?
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