Will these over power my mains?

[PENG]

You're the EE I'm not all that clear on the point in this case, nor do I remember who said it, but I don't need to run my "gains" full on the Crowns so far either in order to achieve clipping levels.

I think it is more semantics than technical. If the thing is fitted on a power amp, mainly in the pro world, they call it gain control, whereas on a receiver, integrated, prepro/preamp they would call it volume control. In pro applications, they probably shouldn't be arbitrarily set to maximum, but rather, set to the point where it would minimize noise and distortions when used with other controls on the mixers, preamps in the signal chain, hence the term "gain structure".

For home use with prepro/preamp outputs that are compatible such as in this case (AV7005 rated 1.2V, XLS rated 1.4V) with the power amp, there is no good reason not to set the so called gain knobs to maximum.

 

[Verdinut]

I have a pair of PSB Image T6 with Marantz SR 7005 receiver.

I got a Crown XLS 2002 for about $300. I intend to power my mains with this - pre out from receiver. I'm wondering if this be too much power for my mains?

The speakers have recommended input power upto 200W with clipping less than 10% (speaker impedence as rated by manufacturer 4 ohm, if that means anything) and the amp 650W @4ohm dual channel.

I intend to keep the dial at 12 O clock, setup audyssey and use the remote. I do tend to play it pretty loud often.

In answer to your question, YES THEY COULD POSSIBLY BLOW YOUR SPEAKERS!

See my comments in Post #22.
Cheers,

 

[PENG]

We need to clarify the function of a gain control on a pro audio amplifier.

The gain control on a pro audio power amp is not, as is the case with an audiophile power amp, a volume control. It is an input sensitivity control, not a power control. It has absolutely nothing to do with output power. It does NOT affect the amp's ability to send out full power to the speakers.

Some experts recommend to turn up the amps LAST, and only loud enough to provide full volume in the room for the loudest peaks. Turning the amp in a turned-up-all-the-way state COULD potentially lead to blown speakers if the amp input gets any spike or huge input signal.

As for the Crown amplifier in question in this thread, I would set it to a sensitivity of 1.4V at the beginning and see if the available volume is sufficient, by increasing the gain control gradually from 9 O'clock with a CD that contains dynamics, for instance an action movie soundtrack or some classical music. A disc that I have and which contains a wide dynamic range is a CD by the South African trompetter, Hugh Masekela. The title of the Album is "Hope" and the last track entitled "STIMELA" which means "The Coal Train" is the one with outstanding dynamics.

Here is a good article on gain structure adjustment and which explains differences between home or audiophile audio and pro audio signal levels:

http://www.hometheatershack.com/forums/home-theater-receivers-processors-amps/35677-gain-structure-home-theater-getting-most-pro-audio-equipment-your-system.html

My short response is, as I mentioned before, for home use with a simple/straight forward avr/avp, just set the so called gain control to maximum. Crown's instruction won't say it because it is designed as a proamp. For home audio amp such as Parasound Halo, they would recommend the knobs be set to maximum too, just to start of course as they are made so one can adjust... It is also just semantics, really, to call them gain control when found on power amps especially proamps, but electrically speaking one can actually consider them volume control though I have no objection to call them differently for reasons cited.

 

[lovinthehd]

I'm still of the opinion to set the gain/level/sensitivity so that the amp just gets what it needs for full power from the signal

 

[PENG]

I'm still of the opinion to set the gain/level/sensitivity so that the amp just gets what it needs for full power from the signal

You stated it in such a generic way that no one can disagree with you.

 

[lovinthehd]

You stated it in such a generic way that no one can disagree with you.

By "just" I mean just "just"

 

[PENG]

By "just" I mean just "just"

I knew that, but one could interpret that you could have meant in conjunction with the other vol/gain/sensitivity controls, and adjust all of those to that "just" point.

 

[lovinthehd]

I knew that, but one could interpret that you could have meant in conjunction with the other vol/gain/sensitivity controls, and adjust all of those to that "just" point.

That's why I'd start with 1.4V and see where on the Crown's vol/gain/sensitivity controls I needed to be. Forgot about the separate 1.4/.775V there for a minute, since my gen 1s don't have that switch.

 

[Verdinut]

I deleted my previous post because I was mislead by supposedly experts in pro audio gear.

Gain control on a pro audio amp and volume control on an audiophile amp are identical. So, if someone advances that a gain control is different, it's real bullshit!

The real fact is that a volume control on an audiophile power amplifier, similarly to the gain control on a pro audio amp, only controls the sensitivity of the input stage. It won't affect the power output of the amplifier. It won't prevent the amp's output stage to deliver its full output with a strong feedback source or other huge input source voltage, unless its resistance value is way up at the lowest setting.

However, I still believe in fixing a system gain structure by adjusting the inline source signal levels first and then fixing the power amp's volume or gain to get adequate headroom. Keeping an amp in a turned-up-all-the-way state could potentially lead to blown speakers.

 

[Verdinut]

My short response is, as I mentioned before, for home use with a simple/straight forward avr/avp, just set the so called gain control to maximum. Crown's instruction won't say it because it is designed as a proamp. For home audio amp such as Parasound Halo, they would recommend the knobs be set to maximum too, just to start of course as they are made so one can adjust... It is also just semantics, really, to call them gain control when found on power amps especially proamps, but electrically speaking one can actually consider them volume control though I have no objection to call them differently for reasons cited.

@PENG,

I did my research and I now agree with you. There is a good argument for fixing the gain control on a pro audio amp to maximum taking into account that the source output of home audio equipment is about -8dB compared to pro audio levels.

Call it gain or volume control, they have the same electrical function. The same risk of blowing speakers exists with both home sound systems and pro audio systems.

To summarize, it is desirable to match an amp's power rating to the requirement of the speaker to be driven, taking into account its power rating.

BTW, I deleted my previous post.

 

[KEW]

@PENG,

I did my research and I now agree with you.

Call it gain or volume control, they have the same electrical function. The same risk of blowing speakers exists with both home sound systems and pro audio systems.

To summarize, it is desirable to match an amp's power rating to the requirement of the speaker to be driven, taking into account its power rating.

BTW, I deleted my previous post.

So, can you really adjust a power amps output so it has enough headroom to accommodate any spikes in the content without going into clipping, but is hard limited to a level that would prevent ever overloading.
If so, is it a practical endeavor for the common music lover/audiophile to determine the correct setting.

I do know that too much power is generally better than too little because clipped signals are very hard on drivers.

 

[M Code]

As one can see there was alot of discussion where to set the input Sensitivity for the Crown Amplifier. I made the recommendation to set @ 0.775V where others said 1.4V..
Here is a copy lift directly from the Crown Operation Manual...

"Input Sensitivity
The INPUT SENSITIVITY feature enables the playback from sources with inherently low output levels to drive the amplier to full power by selecting "0.775 - HIGH." It is recommended that this remain set at the default NORMAL setting for all other audio sources to provide optimal system performance. The HIGH setting is often used with source devices that use RCA connections."

As I previously posted the majority of consumer application/products typically have low-level pre-outs. When used in pro-audio systems, there the pre-out and line levels are typically higher and then the 1.4V setting is used.

Just my $0.02..

 

[Verdinut]

So, can you really adjust a power amps output so it has enough headroom to accommodate any spikes in the content without going into clipping, but is hard limited to a level that would prevent ever overloading.
If so, is it a practical endeavor for the common music lover/audiophile to determine the correct setting.

I do know that too much power is generally better than too little because clipped signals are very hard on drivers.

First of all, with a gain or a volume control, you don't adjust the power output capability, but rather the input sensitivity of the amplifier. The full output possibility is always there, even if the gain control is at -25 minutes. Everything depends on the output voltage of the source, I am just referirng you back to a remote possibility of a spike or a feedback source that could get the amplifier to reach its full power output and blow speaker drivers. The risk always exists, more so if the speakers have a fragile design and don't have a high power rating.

BTW, the power rating of a speaker does not mean the power it will handle continuously, but the maximum power peak that it will take before destruction. However, some manufacturers will rate their products more conservatively. I am just thinking of Altec Lansing which made the 416 Model, a 15 inch woofer which was used in their famous A7 "Voice of the Theater" system. It had a power rating of 25 watts but could handle peaks of 300 watts without damage in a properly designed ported enclosure. However, I would tend to stick to the thought that speakers built today don't have that kind of conservative rating.

I agree with you in that it is generally better to use a more powerful than an insufficiently powered amp for obvious reasons.

I think it is a practical endeavor for an audiophile to adjust the volume/gain control on a power amp so that the power output meets the peak volume demand according to his listening preferences. The way to do that is to start the adjustment by putting the vol/gain control at 9 O'clock and raising it gradually just to the point where the SPL meets the peak demands. IMO, it is unsafe to keep an amplifier input level all the way up if you don't need the extra power. Most of the time, you will find that ½-¾ up is where you will set the knob.

There are several articles on the web with regard to sound system gain structure setting, and which can serve as a guide for home sound systems as well, when using external power amplifiers.

Cheers,

André

 

[Johnny2Bad]

You are far more likely to damage speakers from too little power versus too much.

The reason is straightforward ... with lesser power, you are closer to clipping at any room Sound Pressure Level (SPL) than with a bigger amp. Clipping destroys tweeters easily and can damage any driver.

Assuming you can recognize the sound of distortion, you will naturally turn down the power when it's encountered, which eliminates the problem of clipping.

The only other time where speaker damage is common is when you are trying to fill a large area (perhaps outdoors, or a hall of some kind) and the overall SPL might exceed the natural limits. In an ordinary home setting, on the other hand, this situation is unlikely.

The reason loudspeaker manufacturers offer power recommendations is to help you size the amp to the speakers in a normal home environment. Basically the low end is how much power you should have, for a reasonable volume level, and the high end is how much the speaker is likely to need to play at it's full potential volume, again in a normal home environment. It isn't a strict limit on power, simply because having more than that amount reduces the risk of clipping.

Now, it must be said, that there are people who don't recognize the sound of an amplifier entering distortion. They are likely to overdrive the speakers because the instinct to turn it down doesn't come to them.

I've examined hundreds of speakers for warranty evaluation when I was in the business (you cut them apart and examine the voice coil), and I can confidently say that in nearly 100% of cases, it was clipping that destroyed the drivers.

It should be noted that a drastic reduction of volume below the clipping level isn't necessary; just turn it down a bit so it's no longer distorting. There is little difference in overall level from the clipping point to zero clipping, so your enjoyment of the system should not be drastically affected.

If you are one who likes very loud music, you should choose speakers that can offer that level (high SPL capability) with ideally high efficiency (plays louder with the same power) than typical home speakers. There really is no way around that, even if it means the overall Sound Quality (SQ) doesn't equal the less efficient speaker you may like; it's a trade off that must be made.

In the end, I would not worry about it too much, if at all, if I were you. Use some common sense and everything should be fine.

 

[PENG]

As one can see there was alot of discussion where to set the input Sensitivity for the Crown Amplifier. I made the recommendation to set @ 0.775V where others said 1.4V..
Here is a copy lift directly from the Crown Operation Manual...

"Input Sensitivity
The INPUT SENSITIVITY feature enables the playback from sources with inherently low output levels to drive the amplier to full power by selecting "0.775 - HIGH." It is recommended that this remain set at the default NORMAL setting for all other audio sources to provide optimal system performance. The HIGH setting is often used with source devices that use RCA connections."

As I previously posted the majority of consumer application/products typically have low-level pre-outs. When used in pro-audio systems, there the pre-out and line levels are typically higher and then the 1.4V setting is used.

Just my $0.02..

I read that before I posted anything. Crown audio is not always (I guess it depends on whether the material was written by their design team or marketing team) right about what they wrote on their website, just checked out what they said, or used to say/brag about their high DF and the way exaggerated benefits and you will know what I mean. As a generic statement, I don't disagree with what they said in what you quoted in BOLD. In this case though, we know what that home audio gear is, i.e. the Marantz AV7005 that I know for a fact would have no trouble driving the XLS 1502 to clipping and beyond.

Take a read of the following review by Gene if you are still in doubt:

http://www.audioholics.com/av-receiver-reviews/marantz-sr6004-1/sr6004-measurements

"Preamp Section


Marantz SR6004 Preamp FFT Distortion Analysis

With 0dBFS in, the SR6004 was able to output a whopping 7Vrms unclipped (<.1%THD +N). The 3rd order harmonic component was over 80dBv below the fundamental which was very good. Adjacent channel to channel crosstalk produced 81dB @ 1kHz, 65dB @ 10kHz which again is excellent.

This is not the AV7005, and AH has not bench tested the more recent Marantz AVR or AVP, but one can reasonably expect the most Marantz SR7000 and AV7000 series would have decent outputs regardless of their specified mere 1.2 V rating."

I would have agreed with you, but in this case I am firmly in HD's camp especially as the OP seems concerned about blowing his speakers so why not start with the safer 1.4 V setting and if that's not good enough he can then flip the switch over.

 

[PENG]

So, can you really adjust a power amps output so it has enough headroom to accommodate any spikes in the content without going into clipping, but is hard limited to a level that would prevent ever overloading.
If so, is it a practical endeavor for the common music lover/audiophile to determine the correct setting.

I do know that too much power is generally better than too little because clipped signals are very hard on drivers.

I would assume it depends on the design. I have two power amps that have those knobs, the Marantz SM-7 and Parasound A21. If I turned them to the minimum position I get no sound at all so there aren't any hard limit and I can definitely set them to match a certain preamp for optimal performance.

 

[Johnny2Bad]

With regard to all the talk of Gain Matching, the fact remains that someone has to be in the room listening to the loudspeakers. Regardless of which gain setting is chosen, or the overload characteristics of the preamp, in the end it's either too loud or it isn't. How you get there isn't relevant if the question is about whether you could damage a speaker system with power.

A preamp's ability to generate output levels beyond 0dBu (775mV) or 0dBv (1.0V) isn't about steady-state levels; it's about clean headroom, without which, the preamp would generate square waves (high THD) into the amp that would not need to clip, it would only need to reproduce the square waves, which most amps can do, more or less.

With Digital sources it's not much of an issue ... they can be expected to generate about 2.2V (spec is 2.0, but it's rarely that low in reality) and no more. With analog sources, that will typically generate output closer to 0dBu (0.775V) steady state but may also generate transients of up to +14dBu (typical sources) to +20dBu (classical music). That's where your 7V (or whatever) output needs to be clean. In fact I would prefer a preamp with more than 7V clean headroom, to be honest. I think the one I use now is capable of about 20V at less than 1% THD (the onset of clipping by most definitions).

The source of clipping isn't relevant (aside from the fact that it's undesirable); it can come from any point downstream of the loudspeaker, right to the source component.

 

[M Code]

I read that before I posted anything. Crown audio is not always (I guess it depends on whether the material was written by their design team or marketing team) right about what they wrote on their website, just checked out what they said, or used to say/brag about their high DF and the way exaggerated benefits and you will know what I mean. As a generic statement, I don't disagree with what they said in what you quoted in BOLD. In this case though, we know what that home audio gear is, i.e. the Marantz AV7005 that I know for a fact would have no trouble driving the XLS 1502 to clipping and beyond.

Take a read of the following review by Gene if you are still in doubt:

http://www.audioholics.com/av-receiver-reviews/marantz-sr6004-1/sr6004-measurements

"Preamp Section


Marantz SR6004 Preamp FFT Distortion Analysis

With 0dBFS in, the SR6004 was able to output a whopping 7Vrms unclipped (<.1%THD +N). The 3rd order harmonic component was over 80dBv below the fundamental which was very good. Adjacent channel to channel crosstalk produced 81dB @ 1kHz, 65dB @ 10kHz which again is excellent.

This is not the AV7005, and AH has not bench tested the more recent Marantz AVR or AVP, but one can reasonably expect the most Marantz SR7000 and AV7000 series would have decent outputs regardless of their specified mere 1.2 V rating."

I would have agreed with you, but in this case I am firmly in HD's camp especially as the OP seems concerned about blowing his speakers so why not start with the safer 1.4 V setting and if that's not good enough he can then flip the switch over.

Pls read my posts closely...
The actual pre-out level is determined by the input level of the source.. If one is running high levels sources such as 1V RMS like Gene did in his Test Report one should expect a reasonable pre-amp output level...
However...
When using a low level moving magnet cartridge through the phono source input the preamp output level will be decreased significantly requiring the external power amplifier to be driven harder....
Note that this situation exists with many other brands as well including Yamaha and integra, basically the output voltage swing of the phono preamp is significantly lower making the preamp output level lower as well. This may not matter if vinyl is not a crucial audio source but in my instance vinyl and phono preamp performance is very pertinent.

If one has to increase the Master Volume of the AVR significantly to achieve desired playback levels for the phono source input then its noise floor will increase substantially which is audible and very negative. Also if one has a larger listening room coupled with low impedance/low sensitivity loudspeakers the situation gets worst as higher power output is required..

In my archives library I still have some of the AP measurements for the Marantz AVRs and I will go back and check these more closely. If not available, we still have a couple of Marantz AVRs in the vault and I will try and rerun the AP tests.

Just my $0.02...

 

[PENG]

Pls read my posts closely...
The actual pre-out level is determined by the input level of the source.. If one is running high levels sources such as 1V RMS like Gene did in his Test Report one should expect a reasonable pre-amp output level...

Sure, but you are stating the obvious now, so what is the point, or the problem?

However...
When using a low level moving magnet cartridge through the phono source input the preamp output level will be decreased significantly requiring the external power amplifier to be driven harder....
Note that this situation exists with many other brands as well including Yamaha and integra, basically the output voltage swing of the phono preamp is significantly lower making the preamp output level lower as well. This may not matter if vinyl is not a crucial audio source but in my instance vinyl and phono preamp performance is very pertinent.

I didn't think we were talking about phono input here, even if we were, I still don't have any concerns about the AV7005's preout level or it's sensitivity. I don't use my turntable with my HT system, but I am sure it can do a good job too.

If one has to increase the Master Volume of the AVR significantly to achieve desired playback levels for the phono source input then its noise floor will increase substantially which is audible and very negative. Also if one has a larger listening room coupled with low impedance/low sensitivity loudspeakers the situation gets worst as higher power output is required..

Again, I can agree with you on those scenarios (two "if" s you have there by the way), but the OP is asking about using his AVP with an external amp. Based on the equipment he listed, I doubt he's using the phono input anyway. If he does, I still don't see a problem. Besides he can simply flip the switch over to 0.775V if necessary.

Edit: Your first "if" about the master volume does not sound right, I think you've got it backward again. If the power amp the AVR is driving does not have any input adjustments then you can't do anything about it, but in the case we are discussing, that is reason why I would select the lower sensitivity so that the AVR does not have to attenuate the signal as much.

In my archives library I still have some of the AP measurements for the Marantz AVRs and I will go back and check these more closely. If not available, we still have a couple of Marantz AVRs in the vault and I will try and rerun the AP tests.

Just my $0.02...

I am interested in seeing the numbers, maybe they are close to Gene's, may be not, so let's see..
The OP is asking if the amp could "over power", or damage his PSB T6 speakers, so that's the main reason why some of us suggested he try the 1.4V first, we have nothing against trying 0.775 V next, or after. He obviously could also set the gain knobs below the maximum point, as you suggested earlier.

 

[M Code]

We buy/install quite a few Crown amplifiers as they deliver alot of clean power @ competitive pricing. And we can buy these through our same local SoCal AV distributor we get alot of our audio, video, cameras, connectivity, home automation components from.

Basic reason we suggested setting the Crown amplifer gain controls @ about 70% is through our experience, we found that this setting allowed the amplifiers to deliver adequate power and operate cleanly without distortion. If we needed a little adjustment range we could easily go up or down as the system requirements dictated. Also since Crown moved mass production to China we had some concern for product reliability but to date we have had excellent performance without failures..

Regarding sonic performance of the phono section and preamp output levels, in 1 (in the family room) of my 3 systems I like to use my 7.2 setup for movies but then switch down to just 2.0 for good old music playback. I do have access to a large vinyl collection of primo audiophile vinyl releases and still prefer their sound compared to some of the digital audio tracks. But then again my vinyl components of turntable and Denon cartridge sell for >$2K which to many may be too extreme.

Just my $0.02...