Problem with ML Source

Hello,

I was enjoying a good listening session at Saturday night. During the track 3 on Pink Floyd - The Wall, disc 1, I heard a "pop", like an electric click, sound from left speaker and after that the sound from the panel was completely distorted, even on very small volume.

The volume lever was a bit more than 12 o'clock, and the sound level was quite low in the moment when this happened. I mean, there are scenes with much more decibels in that cd than the point where this happened.

First I unplugged the power cable for a couple of seconds but it didn't help. The panel still was completely distorted. Then I powered off the amp, unplugged the speaker from mains, removed the speaker cable from both ends and then plugged everything back on and the problem disappeared. It didn't happen again, even I used the same volume level again.

What do you think was the problem? Does the speaker have some kind of over-drive protection? Or do you think the problem was in the amp (which would be a bit strange, as there was still the distorted noise coming from left speaker and right speaker didn't have any issues)? It was not a crazy party volume, just normal, enjoyable listeling volume.

My system:
Cambridge Audio 840C cd player
QED Qunex 3 RCA
Electrocompaniet ECI-3 integrated amp (6 months old)
Audioquest type-4
ML Source (a bit more than year old).

The specs of the amp:
Maximum peak current > 60 A
8 Ohm 2 x 70 W
4 Ohm 2 x 120 W
2 Ohm 2 x 160 W

I would appreciate your comments and thoughts on this, as this really scared me - I thought I'd blown up the speaker. I would like to know what caused this.

Regards,
Mikko

First let's see if it's a speaker or amp problem:
Swap the Left & Right outputs on the amp's speaker terminals - if the 'problem' swaps sides you'll know it's the amp not the speakers...

That is something that I should have done first but it didn't come to my mind, unfortunately. After un-plugging and re-plugging everything the problem disappeared and hasn't happened again yet.

Hi Mikko,

The symptoms seem very much like a problem in the amp.

And judging from the specs you posted for it, it does not look like a suitable design for a ML.

An amp that can not double its rated output wattage into every halving of impedance is probably not going to work well with a ML.
The current delivery spec looks healthy enough, but the ratings for wattage into impedance make me wonder.

Also, an ESL panel rarely sounds "Distorted" (unless due to mechanical damage), it either works or it doesn't. So I always suspect something upstream of the speaker when I hear it.

In your case, it seems the amp 'reset' itself after you powered it down. Again, pointing to it as a possible source (no pun intended) of the problem.

Was the amp particularly hot after this occurrence?

I agree

I agree with the posters. Can you give me some idea of how you like the sound? I currently have Aerius i's and am thinking about replacing them with Sources. Thanks. -Bob.

JonFo, what you are saying seems to make sense. Perhaps there be that kind of functionality, which cuts the power if it gets too hot. Altough I thought that it would "mute" the speaker completely, as there was still quiet and distorted sound coming from speaker. Actually quite similar to the sound what is at the end of the song Better (Guns n' Roses: Chinese Democracy), if you know it.

It's too bad that I didn't try if the amp was hot after the insident, but usually it gets only warm after being played on the same levels (around 12 o'clock). After "reset", I continued listeling for about two more hours with about the same volume levels and the problem did not happen again.

I have also heard that amp doubling the wattage when impedance is halved would be good. Anyway, I trusted the good reputation of Electrocompaniet, and I also was convinced by the current delivery and the permission, that "Like all our amplifiers, the ECI 3 is stable in all loads down to 0.5 Ω" that is important for driving ESL panels. (http://www.electrocompaniet.com/products/integrated/eci3.html)

Rbernst929, I do definitely like the sound of the Sources! I think they provide very good value! The sound stage is clear and deep, cymbals are clean and detailed, I also think they provide enough lower frequencies for smallish room.

Edit: amp link added.

Mikvilja, the Electrocompaniet gear is pretty good, but maybe that unit is underpowered relative to ESL and how loud you might want to drive them.

If you are pretty set on keeping the integrated, then I’d suggest exploring adding a powered Subwoofer to the mix, as it will relieve the amp from dealing with power-hungry bass frequencies as well.

But continuing to operate the EC at levels that push it into protection modes will likely reduce its lifespan pretty quickly. So it’s either reduce the volume, or consider alternatives like a sub, or a new amp.

Thanks for your reply, Jonathan!

ECI-3 has a pre-out (both balanced and single ended), which I've planned to utilize for sub. If I the pre-out is used for sub, would I still need to same volume levels for the speakers, so that the amp would still work as much as now for driving the speakers?

I called the EC dealer who sold me the amp but he really could not tell me anything useful. He said that 12o'clock volume should not be an issue with this amp, and that they've demoed those sometimes even with 3 o'clock volume level without problems. He said that it might have been a "once-in-a-lifetime" case, which wouldn't happen again. Don't know what he meant by that, though...

-Mikko

Hi again,

I received a reply from Electrocompaniet. One thing that they proposed as a cause for this problem is the dust in the panel:

"maybe there was some dust on the panel that gave a flashover and this was the electric click you realised."

Could the dust cause this kind of problem? I have to admit that I have been too lazy about vacuum cleaning the speaker panels.

-Mikko

Heh, nice try from the amp vendor, but while plausible, it does not fit the scenario in your original post. If you unplug the speaker AC, the panel looses (slowly) it's charge, but you indicated the highly distorted sound was still there, and not until you powered cycled the amp did it go away.

Even a very dusty panel will only produce short, transient ticks, not highly distorted sound.

Amps are tricky beasts, I once though one of my Monolith woofers had blown, but it was a 20 year old amp distorting in interesting ways. Sent the amp in for service, and perfect performance ever since. Diagnosing that one took some effort.

So my assessment is the same, the amp went into an overdrive instability in that channel, and didn't recover until a power cycle.

If we could find out more about the amp's internal protection devices, we might get closer to understanding what happened. To me it sounds like the amp's left power supply was interrupted (although the ECI-3 link makes no mention of having separate, or 'dual mono' supplies), and you were hearing the remaining charge on the PS capacitors trying to play music, but the voltage was dropping too low, causing distortion. But with 'only' 40,000uF (according to the ECI-3 link), this shouldn't have lasted very long (probably under a minute depending on the volume setting IMO). How long did the distorted sound last, Mikko?

Tosh, I turned to volume down maybe after 10 seconds. Then I unplugged the power cable from speaker for few seconds, then replugged and heard the sound was still distorted. I would say this perhaps took perhaps 30-40 seconds, roughly.

After that I switched off and on again the amp (and also again unplugged / plugged the speaker power cable), after which the sound was back to normal.

-Mikko

I have been trying to get answers still to this problem and confirmation from both the Electrocompaniet and Abrahamsen (http://www.abrahamsenaudio.com). It was Mr. Per Abrahamsen that designed the Classic line for EC but then left the company and started his own business, so I wanted to hear also his opinion about the problem. I'll copy here the full replies that I received from both of the parties:

Electrocompaniet:

First reply:

Lähettäjä: "ext Service Electrocompaniet" <[email protected]>
Aihe: SV: ECI-3 problem?
Päivämäärä: 24. kesäkuuta 2009
Aika: 14:18:59

Hello Mikko,

as long as we can evaluate this problem we don’t think it is the amplifier.

But since you said you removed the power cords from the ML and put them back again and every think works fine…maybe there was some dust on the panel that gave a flashover and this was the electric click you realised.

This maybe shouts down the power supply in the ML until it gets a reset.

It’s just an idea from one of our engineers who uses ML too.

The ECI-3 is not able to do a reset like this, which means if the ECI3 distorted for some in one channel it will still distort after reset.

If the amp runs out of power it will not distort on that heavy way but you can hear that.

It is normally not dangers as long as you react on that. It will not destroy the speaker and will go away when you adjust the volume down.



Regarding your last question, yes, I think the amp is too small. It will of course work fine under normal listen conditions but you get much more out of the speaker with a bigger amp. (I don’t mean playing louder, but the audible quality)

Anyway this has nothing to do with the problem you named.

Second reply:
Sent: 24 June, 2009 21:00
To: ext Service Electrocompaniet
Subject: VS: ECI-3 problem?

Hello Volker and thanks for your reply!

I'd like to correct that the problem did not disappear after unplugging the power cable of the speaker. Sound was still very distorded, similar to what is at the end of the Guns n Roses: Better song, even when I turned the volume to really quiet level.

The problem was fixed after I turned off the amp and also unplugged the ML power cable.

Just to confirm that I understood correctly; can this kind of incident happen if the ECI-3 is played too hard?

NO.

Is it normal and completely acceptable to play ECI 3 for one hour with volume knob pointing at 12 o'clock (straight upwards)? That provides me with good level of volume, as the ML Source has the sensitivity of 90 db/2.83 volts/meter.

Yes, no problem. Overload is audible because of heavily distortions. It will happen in both channels and go away when turning down the volume.
If the amp gets too hot, the thermo switch will turn the amp off for appr. 20min.. The problem you explained is surely not related to overload of the amp. Even if I think the amp is too small for this speaker. It is either a fault in the amp or ML. It is not possible to reset an ECI-3 if it is faulty on that way.

And here is the reply from Per Abrahamsen (the ECI 3 designer):

Hi Mikko,

From what you are saying I believe that the amplifier gets too hot, and a protection circuitry shuts down the amplifier.
Normally the heat is no problem, but if you have the same temperature as we have the these days it may be too much.

I think that the ECI3 is on the edge with your speaker. If everything is normal i.e. normal room temperature, normal sound level there is no problem, but if you push the amplifier too much, it will shut down to protect it selves or the speaker.

I think that when the room temperature goes down or you give the amplifier some more ventilation it will be ok.



Best Regards
Per Abrahamsen

if it has pre-outs... why not get get an ECI amp, sometimes manufacturers gain match their integrated amps and power amp...so you can do just this, otherwise a few simple attenuators or resistors will do the trick.

would be a good question to ask the designer, ask him for the gain levels of both the eci3 and whatever power amp you want to use.

Hi lpaudio2,

I am not sure if I got your point; do you mean that it might be possible to combine the ECI3 amp with another power amp?

Or do you propose to use the ECI3 as a pre-amp?