Ascend Sierra Tower + Emotiva XPA-11 = Burnt Voicecoil

[Pogre]

Thanks for the reply. Just to make sure if we're on the same page regarding volume... When I say -6db, this is from the volume control on the Marantz... Not really sure how all these tie together technically

Volume position doesn't really mean a lot as different sources can have higher input signals. A hot mix can demand a lot of power.

 

[Replicant 7]

Not taking sides here, OP doesn't state how old his EMO amp is. I googled that amp, front 3 channels are 300 each @8 Ohm's or 550 each @4 Ohm's. So umm yeah dude was throwing some serious juice at his speakers. Don't know what the impedance dip is on his speakers.

 

[Pogre]

Not taking sides here, OP doesn't state how old his EMO amp is. I googled that amp, front 3 channels are 300 each @8 Ohm's or 550 each @4 Ohm's. So umm yeah dude was throwing some serious juice at his speakers. Don't know what the impedance dip is on his speakers.

Yeah, it's a powerful amp for sure.

You guys know me, I like it loud sometimes and have the same speakers. I've never heard distortion or misbehaving even with 103 dB peaks at 14 - 15 feet. For both mids to go like that I think would require some serious juice. Maybe there is something to @TLS Guy's DC offset theory...

@jeeper, were you by chance using them outdoors for a party or something?

 

[Replicant 7]

Yeah, it's a powerful amp for sure.

You guys know me, I like it loud sometimes and have the same speakers. I've never heard distortion or misbehaving even with 103 dB peaks at 14 - 15 feet. For both mids to go like that I think would require some serious juice.

Wait, those are the one's you have Pogre?

 

[Pogre]

Wait, those are the one's you have Pogre?

Yup. I have Ascend Acoustics Sierra ribbon towers and the same center channel too.

 

[jeeper]

I can tell what happened. That Emotiva amp fried those speakers from DC offset. Emotiva gear is junk, pure and simple. Obviously that amp is not properly protected from DC offset. Get rid of that amp now, unless you want to keep replacing woofer drivers.

There is never a cap in series with a woofer or mid woofer. Midranges and tweeters always have at least one cap in series with the drivers as part of the crossover. Caps will not pass DC. The clincher here is that the tweeters are OK, which are the most sensitive drivers to overdriving.

You have a power transistor which is failing and passing the DC rail voltage to the mid-woofers, when it gets to a certain temperature point. This will get rapidly worse and cause you a lot of grief.

In the early days back in the seventies, when direct coupled output stages first appeared, this became a problem. I got stung twice. It then became apparent that protection was required for DC offset. There are various ways of doing this. The best, which is used in many amps now, is optocoupler protection.

That's a pretty interesting hypothesis. Especially about the transistor failing after getting to a certain temperature point. Any thoughts on how I might be able to get it tested?

 

[jeeper]

I own the Sierra towers and Horizon too. I've had them very loud, 0 on my dial, and didn't have any troubles. I didn't play it that loud for more than a song or 2, but I measured north of 100 dB peaks at my seat 14' away. It was very loud. Uncomfortably loud, lol.

Long story short, they can handle a lot of unclipped power in my experience. My amp is capable of 300 wpc into 4 ohms. I can't imagine what it'd take to blow that midrange driver, but I'd expect the tweet to go first if it was clipping.

See, that's what I would expect from the Ascends. I don't for a moment doubt the capability of the speakers, but something somewhere went wrong and I'm trying to figure it out... The DC offset under specific conditions theory from TLS is about the best I've gathered so far from all the research.

BTW, I have 2x Hsu VTF MK-5's as well... Good taste!

 

[Replicant 7]

See, that's what I would expect from the Ascends. I don't for a moment doubt the capability of the speakers, but something somewhere went wrong and I'm trying to figure it out... The DC offset under specific conditions theory from TLS is about the best I've gathered so far from all the research.

BTW, I have 2x Hsu VTF MK-5's as well... Good taste!

That's what I'm thinking, those speakers aren't your everyday BestBuy deal speakers. They're a well design speaker.

 

[lovinthehd]

Also curious, did you post this up in Ascend's forum?

 

[jeeper]

Not taking sides here, OP doesn't state how old his EMO amp is. I googled that amp, front 3 channels are 300 each @8 Ohm's or 550 each @4 Ohm's. So umm yeah dude was throwing some serious juice at his speakers. Don't know what the impedance dip is on his speakers.

The entire setup is about 3 years, so not very old
The impedance is 4ohm. http://www.ascendacoustics.com/pages/products/speakers/SRT/srtspecs.html

@jeeper, were you by chance using them outdoors for a party or something?

Ha! That was the first question Ascend asked me as well. But no, I was not. It was during a party, but it was indoors.

Also curious, did you post this up in Ascend's forum?

I did not. We all have our opinions, but I view this site as rather independent and having diverse views.

 

[lovinthehd]

The entire setup is about 3 years, so not very old
The impedance is 4ohm. http://www.ascendacoustics.com/pages/products/speakers/SRT/srtspecs.html



Ha! That was the first question Ascend asked me as well. But no, I was not. It was during a party, but it was indoors.



I did not. We all have our opinions, but I view this site as rather independent and having diverse views.

I think you might not only get more input from perhaps more experienced users of same gear as well as Dave's attention in any case. Don't see anything "wrong" with getting that input as that would diversify views more likely.

ps Have several Ascend speakers and altho not active in their forum much, would just be interested in the info....

 

[Pogre]

Ha! That was the first question Ascend asked me as well. But no, I was not. It was during a party, but it was indoors.

Dave, the owner of Ascend said he's only seen 1 pair of towers fry like that and it was an outdoor party. In that case the whole speaker melted down. Both of them, every driver and the tweets. I think he even fried the crossovers. That story is what made me even think to ask, lol.

 

[lovinthehd]

Parties can be bad. I know.

 

[lovinthehd]

One of the best features of a modern avr is the ability to lock up the max volume....you know, just in case

 

[jeeper]

Dave, the owner of Ascend said he's only seen 1 pair of towers fry like that and it was an outdoor party. In that case the whole speaker melted down. Both of them, every driver and the tweets. I think he even fried the crossovers. That story is what made me even think to ask, lol.

Yep, Dina told me about it as well... something about outdoor Karaoke, and the son snitching on the dad...
I exchanged a few emails with Dave as well and he's the one who recommended that I test the amp with some cheapos. That didn't reveal anything, but then again... not reproducing the exact circumstances

 

[Verdinut]

I don't know if this would be a factor, but they do have the midrange in its own sealed compartment and tuned to roll off naturally to the bass drivers.

If the Emotiva produced a DC offset voltage and there was no capacitor in series with the midrange driver, that could explain the destruction.

 

[little wing]

I have the same 3 speakers across the front on my set up. Ascend towers and horizon center with raals. The last party I had here, was before covid. But somebody cranked the volume up to about -11dBs or so. It was incredibly loud to my ears and when I saw the volume reading ..needless to say I took the freaking remote from them and they never saw it again. My speakers didn't blow thank Goodness. But I'm not using a separate amp, just a Yamaha 3060 receiver. I'm glad Ascend came through for you. A mid range driver on one of the towers did go bad after about a year, and Ascend promptly sent me another one. These speakers do rock though with all types of music especially if you have a sub or two.

 

[TLS Guy]

That's a pretty interesting hypothesis. Especially about the transistor failing after getting to a certain temperature point. Any thoughts on how I might be able to get it tested?

You drive it hard into large power resistors, and watch the output on the Scope and see if DC gets superimposed on the output. I bet that is the problem. I have been there. DC offset is the only time I have burnt out woofer voice coils. I have to admit to burning out the odd tweeter, may be a couple, from over enthusiastic levels.

This problem only started with the introduction of direct coupled output stages. One of the first was the Crown DC 300 A. I also had a very early Quad 405, send a speaker up in smoke. Peter Walker apologized and sent me the clamp circuit for the output. He also gave me new boards, as the output transistors were promptly discontinued, and so that led to the prompt new iteration of the power amp boards.

I would have enormous suspicion of that Emotiva amp. Ascend will probably not be so kind to you if you fry more VCs!

Ascend call that mid range driver, a mid woofer. So I suspect that the speaker is really a 2.5 way, with the cross to mid being acoustic. That is actually I good plan. But that would mean that there would be no cap in series with the midrange. That is actually quite a good design. You might check with Ascend to see if that is correct and if there is a cap in series with that mid or not. If there is no cap, DC offset is likely. If there is a cap, it was not DC offset. Since they call it a mid woofer, I suspect there is no cap in series with the VC.

 

[Pogre]

Ascend call that mid range driver, a mid woofer. So I suspect that the speaker is really a 2.5 way, with the cross to mid being acoustic.

It for sure is exactly that. They're 2.5 way speakers and the mids are in a sealed compartment acoustically tuned to roll off to the woofers. I'm pretty sure there's no cap.

 

[Pogre]

@jeeper you should run the DC offset hypothesis by Dave and see what he says. That's still just a guess (albeit an educated one), but the more I think about it the more plausible it sounds. The conditions are there if the amp is indeed designed the way TLS suggests.