How Many Watts am I using?

[Swerd]

Odd that the impedance peak is 1000 Hz before crossover. However the crossover is second order electrically, as you can tell from the pictures. However both the woofer slope and the tweeter slopes are second order, so when you combine the two you get fourth order. So the tweeter power would be 18 db down by resonance, and so the speaker would handle 100 watts as far as the tweeter is concerned.

I haven't seen a SongTower crossover or a schematic. It's proprietary, and even if I did know its details, I wouldn't reveal it. So I can't directly answer your question. It's my impression that the tweeter impedance peak seen in speakers often can occur at a frequency below the actual crossover frequency. I don't really know how common this is.

All I know is what Dennis Murphy says, the crossover at 2500 Hz is 4th order acoustic LR crossover. Dennis usually speaks of a crossover's acoustic performance and not it's performance as an electronic filter alone. Perhaps Dennis may have something to add.

What info in the graphs I posted indicates 2nd order electric crossover slopes to you? The roll off slopes shown in the simulated reverse null plot are the predicted SPL from the combination of the crossover plus the speakers' measured SPL and impedance data.

From an owner's point of view, I've had my SongTowers since 2007, almost always driven by the B&K EX4420 amp, 200 wpc at 8 ohm load, 350 wpc at 4 ohms, THD 0.09% (all measured at 1000 Hz. If measured at 20 Hz - 20 kHz, the power would probably be somewhat lower). It delivers 75 amps current (peak to peak). I agree it's more power than the STs need, but I've never experienced any tweeter or woofer trouble. Maybe I have a gentle touch on the remote volume control. Dennis uses an old Hafler amp that Frank Van Alstine rebuilt (keeping only the chassis, transformer, and heat sinks) into a 120 wpc amp. It seems to drive any speaker Dennis has tried on it, including the SongTower.

 

[Swerd]

Has anyone actually heard an amplifier running out of headroom?

That's a good question. What does low levels (~10%) of clipping sound like?

The demonstration by Bob Cardell that I spoke of earlier in this thread compared a 100 wpc amp vs. 250 wpc amp driving the same speakers. At SPL levels averaging about 80 dB or less, electronically measurable clipping occurred at brief but demanding snare drum thwacks with the 100 watt amp, but not the 250 watt amp. No one could hear a difference. The demo's point was that clipping happens well before we are aware the speakers sound stressed.

 

[PENG]

I agree it's more power than the STs need, but I've never experienced any tweeter or woofer trouble. Maybe I have a gentle touch on the remote volume control.

That's the thing, if you do have a gentle touch on the volume control, you can use a 1000W amp and won't get into trouble. If you don't, you can get into trouble with a 100W amp, but quicker with a 1000W amp. So I think this amp power requirement thing is overrated to the nth degree, but there is still some truth to TLS Guy's stated opinion that "Contrary to the wisdom round here speakers are usually blown by too much power and not too little." In fact one can argue what he said was literally true.

 

[Verdinut]

Ha. No the voice coil just melted and it got stuck and flipped the protection on the amp. I did this with a 40hz tone so it would be obvious if there was clipping because the tweeter would start making noise.

Sent from my SM-G360T1 using Tapatalk

Ha. No the voice coil just melted and it got stuck and flipped the protection on the amp. I did this with a 40hz tone so it would be obvious if there was clipping because the tweeter would start making noise.

Sent from my SM-G360T1 using Tapatalk

You can see speakers smoking and some catching fire on several youtube pages.
Here is one:

 

[Bucknekked]

You can see speakers smoking and some catching fire on several youtube pages.
Hereis one:

I am not sure what one could learn by watching that video, but it was interesting to see. Kinda like watching car crashes (where nobody gets hurt but the car). I think it goes to show there's a youtube video for everything these days.

Its interesting that when I started this thread, it was about "how many watts am I using?". And it appeared that I am actually burning very few on a day to day basis. But the thread has morphed in to how much power will melt a speaker. That's creativity there. That's taking an idea an running with it. This forum is so much fun sometimes.

 

[RichB]

FWIW here's the bench test of a Denon avr that seems to have the same amp section (see Scott Wilkinson's remark in the comments section, he's the head guy at avsforum.com altho he is more on the video side of things). http://www.soundandvision.com/content/denon-avr-1612-av-receiver-ht-labs-measures#VuGPrtusyDcSCDlQ.97

There are some odd measurements:

This graph shows that the AVR-1612's left channel, from DVD input to speaker output with two channels driving 8-ohm loads, reaches 0.1% distortion at 103.9 watts and 1% distortion at 118.5 watts. Into 4 ohms, the amplifier reaches 0.1% distortion at 73.4 watts and 1% distortion at 141.5 watts.
Read more at http://www.soundandvision.com/content/denon-avr-1612-av-receiver-ht-labs-measures#HloZ2DzwpJD68ccI.99

The amp drops power output at .1% from 103.9 (8 ohms) down to 73.4 into (4 ohms).

- Rich

 

[RichB]

Has anyone actually heard an amplifier running out of headroom? I know what digital clipping sounds like but I've never been able to tell if my receiver is clipping. At one point in time I was using an ultra cheap htib receiver and decides to try and watch a movie at reference level just to see if I would actually get distortion. I know my speakers weren't distorting because klipsch bookshelves show low levels of thd even at 105dB but as far as I could tell the only thing I noticed was that the sound sounded kind of harsh, though this could have been the fact that it was insanely loud.

I've also tried to drive my onkyo tx sr 707 into distortion by hooking an old rat shack bookshelf that was broken on the corner. It was rated for 100w rms, but the speaker blew before I hit clipping.

What other types of things can one get besides straight up clipping? Compression of dynamics?

Sent from my SM-G360T1 using Tapatalk

A clipping amp sounds like less and more.
Less of the signal it should be producing and more distortion than it should be producing.

It depends on the speakers and amp how that turns out. Some amps clip better than others. On receivers, I notice less first. The sound does not increase proportionally, so compressed.

- Rich

 

[PENG]

There are some odd measurements:



The amp drops power output at .1% from 103.9 (8 ohms) down to 73.4 into (4 ohms).

- Rich

Denon rated that unit 75W, 8 ohms. For such entry level receiver, I would de-rate it to no more than 50W for 4 ohm loads.

 

[TLS Guy]

I haven't seen a SongTower crossover or a schematic. It's proprietary, and even if I did know its details, I wouldn't reveal it. So I can't directly answer your question. It's my impression that the tweeter impedance peak seen in speakers often can occur at a frequency below the actual crossover frequency. I don't really know how common this is.

All I know is what Dennis Murphy says, the crossover at 2500 Hz is 4th order acoustic LR crossover. Dennis usually speaks of a crossover's acoustic performance and not it's performance as an electronic filter alone. Perhaps Dennis may have something to add.

What info in the graphs I posted indicates 2nd order electric crossover slopes to you? The roll off slopes shown in the simulated reverse null plot are the predicted SPL from the combination of the crossover plus the speakers' measured SPL and impedance data.

From an owner's point of view, I've had my SongTowers since 2007, almost always driven by the B&K EX4420 amp, 200 wpc at 8 ohm load, 350 wpc at 4 ohms, THD 0.09% (all measured at 1000 Hz. If measured at 20 Hz - 20 kHz, the power would probably be somewhat lower). It delivers 75 amps current (peak to peak). I agree it's more power than the STs need, but I've never experienced any tweeter or woofer trouble. Maybe I have a gentle touch on the remote volume control. Dennis uses an old Hafler amp that Frank Van Alstine rebuilt (keeping only the chassis, transformer, and heat sinks) into a 120 wpc amp. It seems to drive any speaker Dennis has tried on it, including the SongTower.

You can tell the crossover is second order by the picture of it in the Audioholics review. That would make sense anyway from the acoustic slopes of the drivers. 2.5 KHz would be the right place to put it from the acoustic slopes. I don't know why the impedance peak is 1000 Hz below crossover, but likely due to BSC, as the drivers are small and the cabinet narrow, so it is going to start pretty high up.

 

[TLS Guy]

I haven't seen a SongTower crossover or a schematic. It's proprietary, and even if I did know its details, I wouldn't reveal it. So I can't directly answer your question. It's my impression that the tweeter impedance peak seen in speakers often can occur at a frequency below the actual crossover frequency. I don't really know how common this is.

All I know is what Dennis Murphy says, the crossover at 2500 Hz is 4th order acoustic LR crossover. Dennis usually speaks of a crossover's acoustic performance and not it's performance as an electronic filter alone. Perhaps Dennis may have something to add.

What info in the graphs I posted indicates 2nd order electric crossover slopes to you? The roll off slopes shown in the simulated reverse null plot are the predicted SPL from the combination of the crossover plus the speakers' measured SPL and impedance data.

From an owner's point of view, I've had my SongTowers since 2007, almost always driven by the B&K EX4420 amp, 200 wpc at 8 ohm load, 350 wpc at 4 ohms, THD 0.09% (all measured at 1000 Hz. If measured at 20 Hz - 20 kHz, the power would probably be somewhat lower). It delivers 75 amps current (peak to peak). I agree it's more power than the STs need, but I've never experienced any tweeter or woofer trouble. Maybe I have a gentle touch on the remote volume control. Dennis uses an old Hafler amp that Frank Van Alstine rebuilt (keeping only the chassis, transformer, and heat sinks) into a 120 wpc amp. It seems to drive any speaker Dennis has tried on it, including the SongTower.

I have replaced two tweeters in the last month! One I'm pretty sure was due to age, as it was 34 years old. Either wire fatigue, or the ferrofluid drying up and no longer being effective.

The other was a tweeter in the SEAS coaxials. I expect that was J.S. Bach's fault. He really puts the power on the high flue pipes and the gritty reeds. The H.F. power is colossal in a lot of his great fugues.
The rig never sounds stressed and the center has to keep up with the larger mains. The VC on that center tweeter was darkened and the ferro fluid had been over heated. The tweeter worked but was down 6db and had lowered DC resistance due to shorted turns. Crossover is at 2.9 KHz, and I used third order electrical slopes rather than second which I would have liked to have used, as I was worried about this happening. It still did, so I will have to be more careful.

 

[Swerd]

You can tell the crossover is second order by the picture of it in the Audioholics review.

I had forgotten about that photo in the review. Yes, they look like 2nd order electrical filters.

 

[Swerd]

I have replaced two tweeters in the last month! One I'm pretty sure was due to age, as it was 34 years old. Either wire fatigue, or the ferrofluid drying up and no longer being effective.

The other was a tweeter in the SEAS coaxials. I expect that was J.S. Bach's fault. He really puts the power on the high flue pipes and the gritty reeds. The H.F. power is colossal in a lot of his great fugues.

So the coaxial tweeters played Bach for their own funeral. Go ahead, blame it on the dead guy .

 

[Verdinut]

I am not sure what one could learn by watching that video, but it was interesting to see. Kinda like watching car crashes (where nobody gets hurt but the car). I think it goes to show there's a youtube video for everything these days.

Its interesting that when I started this thread, it was about "how many watts am I using?". And it appeared that I am actually burning very few on a day to day basis. But the thread has morphed in to how much power will melt a speaker. That's creativity there. That's taking an idea an running with it. This forum is so much fun sometimes.

Buck,
Did you happen to peruse my post on page 5 of this thread, as a reply to TLSG, in which I was suggesting that you perhaps look into the possibility of getting a pro audio amplifier like a QSC RMX850a, if you have trouble finding a Quad 909. I was asking for his opinion but he never replied.
I know he prefers the Quads but that could be IMO a good alternate option.

 

[Bucknekked]

Buck,
Did you happen to peruse my post on page 5 of this thread, as a reply to TLSG, in which I was suggesting that you perhaps look into the possibility of getting a pro audio amplifier like a QSC RMX850a, if you have trouble finding a Quad 909. I was asking for his opinion but he never replied.
I know he prefers the Quads but that could be IMO a good alternate option.

I did happen to see the reference and recommendation. I took a look at the QSC products and while I was at it I revisited the Crown professional amplifiers as well. All are worthy amps and look like great sources of good clean watts. There are no end to good and excellent choices. I hope to begin to narrow it down sometime soon. So many new suggestions keep cropping up it makes my ADD feel right at home.
Ohhhh.......squirrel...........

 

[highfigh]

Agree, it is obvious that a lot of people either don't notice or don't care about a few % distortions of any kind. People used to crank those 5WPC to fill their room and not bothered by the distortions that probably were >10%. Mind you, those Telefunken/Grundig radio/amplifiers were all tube stuff.

https://cdn.globalauctionplatform.com/b90aeb51-f66d-4b55-82d9-a4d800ad532a/61d6bab6-ed2c-4594-8582-bcca7cbfa533/540x360.jpg

This wasn't Telefunken/Grundig, this was Sony, Pioneer, Harman Kardon, Sansui, etc. When the Sansui R-series of receivers came out and an insane % blew up, someone commented about it and our service tech said "They put the output transistors in to protect the fuses".

 

[PENG]

This wasn't Telefunken/Grundig, this was Sony, Pioneer, Harman Kardon, Sansui, etc. When the Sansui R-series of receivers came out and an insane % blew up, someone commented about it and our service tech said "They put the output transistors in to protect the fuses".

Must be some very high end expensive fuses that needed solid state protection..

 

[Bucknekked]

This wasn't Telefunken/Grundig, this was Sony, Pioneer, Harman Kardon, Sansui, etc. When the Sansui R-series of receivers came out and an insane % blew up, someone commented about it and our service tech said "They put the output transistors in to protect the fuses".

Grundig. I haven't heard that name in ages. My first wifes mother was German and their family spent time in Germany. Their console stereo (when was the last time you saw a console stereo unit) was a Grundig unit. At the time I was awestruck because they told me, in hushed reverent tones, of the stellar quality of German engineers. That's why we couldn't play the rock n roll on it. It was "too good for that".

 

[moves]

I think what is important is headroom. I don't have an SPL meter but The meters on the Mcintosh can hit the 300W mark on very loud peaks. On the regular, it is hovering around probably less than 2 watts for t.v. Music, the amp meters can hover between 20 - 30 watts... but this seems high based on what everyone else is saying here.

What did I learn from the experiment to see how many watts I am actually using when I sit and listen to music? I typically listen at the 80db level for the average evening. When I want some zz Top and I want it loud, the 90db setting comes in to play. When I want it louder than that, its rare, I can get there too. Remember, my room is only a 10x10x10 sealed cube. I am not playing Carnegie hall here.

At 80db, I am probably not burning more than 1w out of my AVR. Night in and night out, I use the 80db listening level. 1 watt. At 90db, a pretty loud setting, I'm still not burning much more than maybe 2 to 3 watts (peaks will be more etc etc).

What that tells me is that a desire for more watts (a seemingly endless want) is simply not warranted or supported by the facts. I am a rock n roll guy, learning to appreciate jazz and the blues. Needing "more watts" has been a thought in my head for as along as I can remember. A cherished notion.

I think, all in all, the numbers tell me that if I buy more watts, I will just be heating the room with most of them. I can't approach amplifier clipping because I will get driven out of the room first. It would seem, if I am understanding the results, more power in the amp/avr is like a muscle car in Manhattan.

If this is true, its must be frustrating to answer all the "I need a new amp for more power" questions that the AH forum sees week in and week out. I see a lot of folks start their posts with "I need more power to drive my new xyz speakers, what should I buy?" or "I want these new xyz speakers and I know my AVR isn't as good as a real amplifier".

I still want more power. Its still in my head. But now, I think I will hold on to the cash for something else.
Maybe, I can get some more slide rules for my collection. Perhaps there's one out there for sound pressure or wattage.

 

[yepimonfire]

I think what is important is headroom. I don't have an SPL meter but The meters on the Mcintosh can hit the 300W mark on very loud peaks. On the regular, it is hovering around probably less than 2 watts for t.v. Music, the amp meters can hover between 20 - 30 watts... but this seems high based on what everyone else is saying here.

It's going to be highly dependent on content and the speakers in question. If you listen to a lot of rock music, you'll be lucky to have a 6 dB dynamic range.

Like I previously said, if you have a relative volume control, you can determine what the peak could be, then add 3dB to account for impedance drops across certain ranges. I generally listen to rock at 75dB, with the volume knob turned to -30dB, at this level, I am not even using a full watt, even adding 3dB of headroom. If I'm listening to classical, I'm much more likely to turned the volume control to -15dB, at this level, I'm now using 9 watts.

I have fairly sensitive speakers, so let's assume someone has a large room where the main listening position is 10 feet away and they're using speakers rated at 87dB. If they were to watch a movie at 5dB below reference level, they would need 180w, at reference level, 460w.

It all depends on what speakers you're using, what the dynamic range of the content is, how big the room is, and how loud you intend to listen.

For the majority of medium-sized living room setups listening well below reference level, 100wpc is more than adequate. In the majority of circumstances, people need a lot less power than they think.

Sent from my SM-G360T1 using Tapatalk

 

[highfigh]

Must be some very high end expensive fuses that needed solid state protection..

No, just crappy receivers.

Sansui had lost their way and eventually closed, but someone bought the name and is now putting it on cheap TVs and other stuff. I was never a big fan, but some of their old integrated amps were pretty nice.