DIY Class A/B Amp The "Wolverine" build thread

[miran50]

Thank you it has been a work in progress for sure! I have measured the IMD on multiple builds and it measures just as good as the rest. What specific IMD test and level would you like to see? The English from the translator is perfect by the way.

Did you test the IMD for 19 and 20kHz ??

 

[fireanimal]

Did you test the IMD for 19 and 20kHz ??

I can get that for you, leave it with me.

 

[poiy]

Hello guys
I finished building my AMP yesterday and I was brave enough to start in today. Unfortunately I could not get any sounds out of it
I used the SMPS Cobra-S2 from Microaudio but it seems to go directly into protect mode, at least the LED is red. Does anyone of you have an idea what I'm doing wrong?

 

[Cresnet]

@poiy

Disconnect your amplifier modules and power up the SMPS, and see if it starts normally.

If the SMPS starts then check your amplifier modules for short circuit or any other possible reason causing the SMPS to go into protect mode.

Sam

 

[poiy]

I made a pretty stupid mistake.
I unfortunately connected the boards as if they were symmetrical and well, then I stupidly confused + and -.

 

[poiy]

The SMPS works corretly

 

[wirewiggler]

Wow that was quick reply from Sam, doubt you could get Hypex to respond in a week. Cross fingers it did not damage amp .
Bill

 

[poiy]

Strangely enough, I got the channel that was connected incorrectly to run briefly. Then I unplugged the cables of the connector and plugged again because I thought maybe they are too loose on the other channel. I then checked both again but after that I had no sound on the briefly working channel.
I'll get to it tomorrow, today I'm done

 

[sp33ls]

@poiy
causing the SMPS to go into protect mode.
Sam

Thank you for building in such features, Sam.

 

[stuartmp]

@poiy The amplifier has reverse polarity protection. It you connected your DC rail voltage incorrectly the Amplifiers rail fuses would have immediately blown.

 

[Cresnet]

The SMPS protection circuit is too fast to allow the fuses to blow.

 

[Vunce]

Very nice Stuart 😉

 

[Cresnet]

I made a pretty stupid mistake.
I unfortunately connected the boards as if they were symmetrical and well, then I stupidly confused + and -.

I suggest that you test your amplifiers using a low current power supply before powering them from the SMPS again.

Thanks

 

[ghitus]

Agree, I would use a dim bulb tester and/or a variac.

Gaetano.

 

[sp33ls]

@Cresnet, is it alright to use the Cobra on a dim bulb tester?

 

[Cresnet]

@sp33ls ,

No, COBRA-S2 won’t start up with a dim bulb tester as it will remain in protect mode.

 

[mhuth1776]

I have heard the opposite.
I've heard that stacking them gives you the opportunity to rotate and flip them to reduce/cancel the noise and EMI
produced.

Twin Toroids

Yes, stacking them gives you the opportunity to cancel fields. I was surprised to see the data sheet where stacking was contra-indicated. It was only in one that I came across while looking at various transformer manufacturers. I cannot seem to find it again. My real point is to look at the manufacturer's data sheet carefully.
There are two possible reasons I can think of not to stack. One is the added torque on the longer mounting bolt. Second is the fact that stacking reduces the area through which heat can be dissipated. This latter is not likely to be a problem in use, but might show up during testing.

 

[wirewiggler]

I was wandering about startup on my cobra2 as well, I have a 50V 5A linear bench bench supply to test it on before I move it to the switching power supply. For the initial power up testing what should I limit current to?
Thanks
Bill

 

[fireanimal]

Reference the build guide. Use very low current fuses in the rails and either a light bulb tester or better yet a variac.

 

[stuartmp]

what should I limit current to

Check the build guide. Limit the current to what it mentions or 75% of your fuse rating should be ok for start up checking. Also 30v rails is sufficient voltage to do an initial test.