Accidentally hit my Theos w/ amp cranked ALL THE WAY UP! Damage?

Hello gang,

So I just bought a brand new integrated amp from a well known manufacturer that pushes 400 Wpc @ 4 ohms. The amp has software which allows me to control it with my laptop via an Ethernet cable. Part of the software control is the Volume control. I had the volume on my laptop set a nominal level that I had already been playing through the Theos, but somehow it glitched and the amp was actually at maximum volume. I had it muted, went over and dropped the needle onto my album, came back to the laptop and un-muted, and was hit with the loudest squawk of distortion I have ever fed my new Theos. It took me literally half a second to react and mute it again. I also have a Descent i hooked up to the speaker level outs of this new amp to the speaker level inputs on the sub.

The Theos and Descent i still sound great but I am curious if that .5 second of max power could have done some type of damage to them? Isn't there some internal gizmo on the Theos & Descent i that would shut them down in the event of an overload to protect them? Blow a fuse, etc? Thanks in advance... Homer

Hola. There is no way to do that. The signal will always get to the speakers and sub. Now, what you did apply to them was a distorted signal. This signal is called clipping signal and it is part of it, DC. This is the reason why you got that horrible sound. If you react that fast, and everything is playing as it should, I think there is no harm to the amplifier, speakers and sub.

You are learning how to use your system the hard way. Now that this happened to you, you will be very aware about it! You will never forget it too.

You do now worry. Shi* happens. Long time ago, I was with the DBX stuff. These devices, brings down the noise and hiss of the system, and you do not know if the system is on or off. I was in another room, and a friend came in. Because I was very busy at that moment, he went to where I had my system. My preamplifier was showing infinite and 0dB. He thought that 0 meant no volume, and he played a record. That transient bleu my speakers. The four woofers were damaged.

Since then, nobody touches my system. No matter how knowledge he or she might be. I do not want that to happen again! Happy listening!

Hello Recardo and thank you for the reply my friend. Well good, you make me feel better because I was worried that I damaged something. Yes, I did learn a lesson - to be more careful when brand new gear is introduced into the equation of my system. Much appreciated...

If something is broken, your ears will know right away. Move the balance to one channel, turn off the volume of your sub, then play some music. Play a well known track. Bring your ears closer to the speakers and listen carefully. Trust your ears!. If everything is OK, do the same thing with the other channel. This will make you know that nothing had happened!

Do not worry, and enjoy your system. The more you use it, the better it becomes! Happy listening!

Homer_Skins said:

The Theos and Descent i still sound great but I am curious if that .5 second of max power could have done some type of damage to them? Isn't there some internal gizmo on the Theos & Descent i that would shut them down in the event of an overload to protect them? Blow a fuse, etc?

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On the SL3 there is an overvoltage circuit of diodes and a mosfet to protect the ESL. IIRC it kicks in at ~200V. I guess newer ML's have something similar?
I would be worried about the woofers though.

Hello Tosh, what would be different or unique about the woofers that I should have to worry about? I also sent an email with the same concerns to MartinLogan's Tech Support.

Thanks...

If it all sounds fine after the incident, no worries and consider yourself lucky.

As Tosh said, check the woofers.

GG

Hello Gordon and I appreciate you taking the time to comment on my post. The woofers are still producing sound as they used to. Other than that, what might I be listening for to tell me I may have damaged them? These 8" woofers really don't produce a lot of low end, and that is why I have incorporated a Descent i sub into the equation. Thank you for your assistance on this matter.

So far everyone has given you good advice. However, it is possible to damage the speaker and the distortion you hear later is less than completely obvious. The MLs have protective circuitry. On the Prodigy and CLX this circuitry is on a board called the DEC. Essentially this is what Tosh was describing in the SL3. With a singer and a single instrument at normal volume its possible you might not detect the problem. Put on something more complex with some vocal harmonies and multiple instruments with which you are very familiar, say like something from the Eagles. Push the volume somewhat. If you say "that sounds great" you are probably fine. If you say that sounds loud or a little off you may have some damage and you will need ML's help.

Gary

I had similar experience with very similar speaker to yours - Vista. After I bought some BAT preamp with remote having "unity gain" button.... long story short, over 1000w went through my speakers for a couple of seconds. Panel took the abuse without any problems, all electronics inside were fine, but woofers literally jumped out the cages. Damage was quite audible.....
Don't worry if it sounds fine, it probably is.

To the best of my knowledge, the panels are pretty much bomb proof.

To check for woofer damage, put on some heavy bass material and play at an aggressive volume.

Put you ear right up to the driver. If it is damaged, you will hear a "scraping" sound. If you don't, all is fine.

GG

Well, I do believe my Theos' woofers are fine, the Descent i sub as well. I did a test as suggested above and put on my Robert Ludwig Mastered LP of Steely Dan's Gaucho which I am very familiar with and is also bass heavy. I cranked it up louder than usual and turned off the sub and only listened to the two 8" woofers built into the Theos. They sound the same as before the "distortion blast" - no scraping or any other ugly sound being produced. I had it ups so loud for the testing that I didn't hear my doorbell ring. It was my neighbor coming over to ask me to please turn my music down because she couldn't even hold a conversation in her living room! My daughter was in her room watching Mr. Peabody and Sherman and came out to tell me someone was at our front door. Not only does my poor neighbor get the bass from the Theos and my Descent i sub, but I also have two 10" Earthquake Supernova subs on the opposite side of the living room than the main rig, one on each side of my couch listening position. They each have a Sunfire wireless receiver which receives the signal from a Sunfire wireless transmitter getting its signal from the sub out on the Descent i. I love this extra low end both for hi-def blu rays and my regular 2-channel music listening pleasure. I am a drummer and I likes my kick drum!

On a side note, where do I go in my profile to add pictures of my system like you guys have so you can click a "hyperlink" and see the pics? Thanks my MartinLogan brothers (& sisters?). Dana a.k.a HomerSkins

Seems like you got away with it -- this time!

Yep, but I am still curious as to how MartinLogan will reply as far as if they think I did some damage or not. Sorry if I sound like an idiot, but if I indeed did do some damage, you guys keep referring to the 8" drivers. Does that mean, I literally only did damage to the 8" speaker cone/ basket itself or did I also damage some internal crossover circuitry board? I don't mind if I have to end up having to replace the two 8" speakers themselves. Piece of cake and some cash - it's that other stuff that I am not sure of. Thanks again! Dana

Warranty, my friend. ML will likely help you out. However, if they sound fine, then they are fine, in my opinion.

Homer_Skins said:

or did I also damage some internal crossover circuitry board? Dana

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Unlikely. Consider yourself lucky and move on.

GG

Unlike the older models, one of the big benefits of the DSP-based low-frequency section in the Theos is that they probably have designed in a limiter to prevent damage in exactly these situations.
They've modeled the max drive the woofer can take, coupled with the max output of their built-in amp, and configured a limiter to not allow over-excursion of the driver nor overdrive of the amp.

I do this in my DBX DriveRack processor for my subs, and it has saved them twice.

As others have said, it's really hard to damage the ESL portion, at worst, some electronics in the crossover or step-up board would go. So if they pass the tests others have suggested, then you are probably fine.

Theos is passive, JonFo...

Tosh said:

Theos is passive, JonFo...

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Doh! - right you are Tosh, it is passive. I just can't seem to remember that little fact. The Montis is DSP.

So to the OP, you should indeed check the woofer carefully for possible damage.

Thank you to all that responded. I do think my Theos and Descent i are fine and have no damage. I also emailed MartinLogan Tech Support and told them what had transpired and here is the response I received from them:

"Thank you for your email and I am sorry to hear of the issue with the volume control. Yikes

1. It is not likely that a surge of this duration would do any long term damage to either the Theos or the sub.
2. The sub has a “limiter” built in which should help to guard against sudden surges. In short the sub will only allow itself to play so loud.
3. The Theos is not fused, so a long term over-powered situation may damage the woofer (or in a more extreme case, the crossover) but would not damage the panel itself. It is unlikely That the short surge you experienced has damaged either the sub or the Theos.

In short, I think you are probably ok. If the speakers still sound fine, it’s unlikely that there was any damage."