SUNN Beta Lead solid state amp no sound

[Darlington Pair]

Just as a quick check for something unlikely but possible - measure the amp output with a DC voltmeter. Ideally have a speaker hooked up to sink any parasitic current. You're looking for problems with the amp producing constant DC, which is *not* something speakers will enjoy. If your speakers are all dead, maybe just a light bulb or a big resistor. Make this measurement with no signal present.

This.

Nothing kills a voice coil faster than DC.

Quote:
What could go wrong that there is not DC isolation there?


Aren't betas solid state?

Ergo, no output transformer.

So leaky coupling caps could indeed put some DC into the speakers, cooking them directly, or at least handicapping AC performance.

No coupling caps on the output of this one. It just relies on the complimentary NPN/PNP transistor pairs to be balanced and biased so there is no DC offset.

[kevin206]

I'm learning a lot from this thread. Keep it updated until the problem is solved. Please!

I've only fried speakers by pushing too much wattage into them. I actually melted the shellac ( or whatever the stuff is) on a voice coil once. The speaker would make a tiny little sound, but the cone wouldn't move. It was "glued" in place!

I did fry a transformer in a SS guitar amp (Fender M-80). My buddy borrowed my amp for a practice and used a guitar cable instead of the heavier speaker cable to hook up to the cab. I'm not sure why the transformer went dead, but that was the only thing "abnormal" about the situation.

Good luck on the Beta.

[Snarl 12/8]

I've only fried speakers by pushing too much wattage into them.

Are you sure? For years I thought my Hafler was such a badass for all the speakers it killed, until I realized that it killed them all from underpowering them. The shame.

[Randyman...]

I've only fried speakers by pushing too much wattage into them.

Are you sure? For years I thought my Hafler was such a badass for all the speakers it killed, until I realized that it killed them all from underpowering them. The shame.

"Underpowering" can be a misnomer. After all power basically equals heat or work. It takes a certain amount of power to kill a speaker - you can hit this power level with a perfectly clean waveform with a oversized amp, or you can reach this power level with a heavily clipped waveform from an under-powered amp driven into heavy clipping. In both circumstances, the total power (HEAT) put into the speaker surpasses what it was rated for. A 50Watt amp (rated clean) can likely put put well over 100Watts clipped - so a 50 watt amp can blow a 75 watt speaker if you clip it enough.

Clipping in and of itself does not blow speakers (DC is not "good" for speakers in general, but assuming you don't put more DC Power into the driver than it can dissipate, it won't fry the coil, but might damage the suspension and screw up the magnet).

Sending too much power (clean or dirty) into the coil is what burns the coil eventually shorting it or burning the coil open. The dumb coil of wire doesn't care what TYPE of power it sees - it just cares about the total amount of power it can dissipate (how much heat it can shed)...

Tweeters are a little different story, but this is due to the fact that a tweeter in a 100Watt full-range system generally only needs to handle 10-20Watts under clean listening conditions (this generally works fine). Once you start clipping the low-end, the 10-20watts that was going to the tweeter ramps up to get the full output power of the amp - and tweeter goes "poof".

It's not the clipping itself that blew the tweet - it's the fact that we are changing the power distribution and allowing that 100 Watt full-range amp to clip in the lows, but the highs will naturally see more power as you crank the volume knob (so the treble range ends up with much more than the 20watts it should have in a clean 100 Watt full-range system).

[kevin206]

I've only fried speakers by pushing too much wattage into them.

Are you sure? For years I thought my Hafler was such a badass for all the speakers it killed, until I realized that it killed them all from underpowering them. The shame.

When I originally posted that statement I was only thinking about pro audio situations. I've "blown" 6x9 car speakers by underpowering them along with the tweeters in some small Realistic bookshelf speakers. My blown pro audio speakers were indeed overpowering. I had read about the problems with too little power, so I made sure to get power amps with higher wattages. I've blown subs, typically. There WAS warning, but I wasn't quick enough to realize WHERE the distortion was coming from...I was generally doing live sound for metal bands, so distortion was everywhere!

Come to think of it, I burned out the tweeters in my first PA by underpowering, so began my quest for big amps.