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Damaged Dome Mid-Range

I have an Energy Veritas 2.3 with a damaged 2 inch dome mid-range driver. It has been suggested to me that the problem with the driver is related to the diaphragm, voice coil, or both. The symptom of the damage is distortion that is apparent during use. I use the speakers for everything ranging from two-channel to movies. I can be an aggressive listener. The speakers are powered by an Adcom GFA 7000 (for the lower end) and a Denon 2803 (mids and highs). The Denon is obviously also pulling duty for surround processing... The stated power output for each (20-20 / all channels driven) is 130 and 90 watts, respectively. The speakers are rated at 200 watts.

Now to the questions. Is the damage done to the driver likely the result of the Denon clipping during a high output scene during a movie? If this is the case, I can surmise that 90 watts is insufficient? Though I don't think so, is it possible that I have the mid-range and tweeter over powered? Why would the mid-range sustain damage and the tweeter not?

A local dealer suggested that the Denon didn't clip, but sent pure voltage to the speaker and that is what damaged the driver. Don't know what that means. Any credence to this notion? If so, what happens and how do I avoid it?

I know this is a lot to chew. Any brilliant responses appreciated. :)
mordenmail
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shadorne's avatar
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shadorne
7,477 posts
 
Eldartford,

Thanks - you are correct.

A good power amp would have power rails around +/-75 volts or more. It is indeed possible that the Denon 2803 HT Receiver has much less - however I doubt it would be less than +/-50 Volts.

This could be a problem if the Veritas was a high impedance load in the midrange or treble!

The 2.4i Veritas seems to rise only to 15 ohms - if the Denon indeed clips at 50 volts (a wild guess) then I'd estimate the maximum power it can deliver at 15 ohms would be about 70 Watts. So it is possible that this might be a limiting factor rather than the amp "spec" into 8 ohm load.
eldartford
4,262 posts
 
Shadorne...The output voltage capability is limited by the power supply rail voltages, no matter how good the transistors may be.
shadorne's avatar
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shadorne
7,477 posts
 
Actually, it's the peak voltage that's needed, and it may not persist long enough to represent much power.

I agree that voltage is needed - some good MOSFETs should be all that is needed though and voltage is a lot easier ti supply than high amounts of current.
eldartford
4,262 posts
 
Mordenmail...Audio amps are designed today with power supplies capable of continuously delivering a certain level of output voltage. Some time ago some amps were designed with power supplies that could deliver high voltage, but only for a brief time interval. For this brief time a high power output could be measured, for example 100 watts for 1/2 second, but only a much lower power could be delivered continuously. Although there is some logic to such a design because music power only peaks briefly, it was criticised as false advertizing, and now all amps are rated for continuous power and designed accordingly.

Bottom line is that if you want high voltage swing you will need an amp with a power rating well in excess of the actual power of the music signal.
electroid
283 posts
 
"A local dealer suggested that the Denon didn't clip, but sent pure voltage to the speaker and that is what damaged the driver.'

well that's kinda properly stated. When an amp clips it sends DC to the voice coil which can burn it over time.....that time could be a second or a minute, depends on the level and type of signal sent.

ET
mordenmail OP
23 posts
 
Eldartford,

To avoid a repeat of this latest disaster, I need a high-power amp that will deliver a high peak voltage. Is peak voltage a spec I can look for when shopping for an amp? What would be considered high voltage?

By the way, thank you to everyone who has offered help to this point.
eldartford
4,262 posts
 
Shadorne...
"You really only need the mega watts for the bass drivers".

I used to think that until I made some measurements. Actually, it's the peak voltage that's needed, and it may not persist long enough to represent much power. However, the way our power amps are designed, only the high power ones have the voltage swing.
shadorne's avatar
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shadorne
7,477 posts
 
Shadorne,

Am I correct that you suggest that I have enough power and may be over-driving the mids and highs?

Yes - if you are sending 90 watts to the mid and tweeter alone then this should be more than enough. You really only need the mega watts for the bass drivers...those are the drivers that move most of the air.
mordenmail OP
23 posts
 
Shadorne,

Am I correct that you suggest that I have enough power and may be over-driving the mids and highs?
mordenmail OP
23 posts
 
Elevick,

I'm not entirely sure when the damage was done. However, I do watch movies and listen to music at pretty loud levels. I tend to push the volume as close to reference as I feel the system can handle. By reference I mean double zero on the receiver. I never get there, though, and I listen for any strain in the sound (distortion, change in pitch, loss of low-end punch, etc...) faithfully.

If I understand you correctly, you feel that the amplifier section of my system is under-powered? How much power would I need to avoid a repeat of this situation?
shadorne's avatar
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shadorne
7,477 posts
 
This 2 inch dome is crossed over at 550 Hz. I would suggest you are playing it too loudly (this is not a speaker that can play extremely loud). When you biamp you can send a lot more power to the mid and high. What goes first is just a matter of luck - in this case your tweeter is also working quite hard (crossed over at 2 Khz).

If you are an aggressive listener then get pro speakers or horns - most consumer designs simply can't take it (they are made for consumers - you get nice looks and/or veneer instead of beefy drivers...)
elevick
2,636 posts
 
Most speakers can handle 200 watts of clean sound. Most can NOT handle 1 watt of distortion. Hard loud was it in your room? The Denon may not be the only culprit, everything together in your system can add up to a little distortion when driven to their limits.
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