Re: Multi Amping
With all respect, I'm sure your system sounds very good but my question was how you came to the conlcusion:
To which you did not answer.
You seem to overlook the fact that loudspeaker distortion increases when the voicecoil is driven from a low impedance. There is nothing that says you can't use a high impedance drive and your active aproach in tandem.
See what I'm getting at?
/Peter
Magnetar said:
With all respect, I'm sure your system sounds very good but my question was how you came to the conlcusion:
To which you did not answer.
You seem to overlook the fact that loudspeaker distortion increases when the voicecoil is driven from a low impedance. There is nothing that says you can't use a high impedance drive and your active aproach in tandem.
See what I'm getting at?
/Peter
Zero One said:
Have you ever investigated how much of this that comes from the media/format and how much is from the specific apparatus and from what is put on the record?
I don't say red book CD is perfect but I don't think people realise what they are listening to.
Loop a LP or a SACD via a high quality 16/44.1 chain in a blind test and get back. These days I have problem to take folks seriously that has not done that. 😉
The major reason CD's often sound bad is becasue the recording and mastering is of poor quality. Also there are CD players that have flaws. Done right I think most people can't tell if a signal has passed a ADDA chain.
/Peter
Someone mentioned dome tweeter can't handle 1000W peaks. Dynaudio and other companies routinely tests their drivers with 1000W transients.. even tweeters and they show little compression. That means peak spl's at 120dB or above. I sure as hell don't need more than that above 2kHz in my listening room.
I know one manufacturer that have made pulse tests on dynamic drivers with 10000W. I think even the dome tweeters are tested this way. The drivers don't break from this.
Then of course there are lot of low quality stuff on the market that would fall to pieces at power levels like this.
/Peter
I know one manufacturer that have made pulse tests on dynamic drivers with 10000W. I think even the dome tweeters are tested this way. The drivers don't break from this.
Then of course there are lot of low quality stuff on the market that would fall to pieces at power levels like this.
/Peter
Pan [/i][B] I have also measured some good dome tweeters and I'd say in most situations they are just fine. I thought the thermal compression would be much worse but for normal use there is no problem. Typical program material have low power in the area above 1-2kHz. Would you mind telling how serious you found the compression to be? [/B][/QUOTE] It was a very seriuos problem - as much as 6 dB at 10 kHz. I'll post my data if you'll post yours and we will see what the data says. [QUOTE][B] I can't see how that can be true. A dipole put out less energy in the room for a given on axis output hence it must excite standing waves to a lesser degree than a monopole. I agree though that multiple monpoles makes sense in the low bass area.. say below 80Hz. [/B][/QUOTE] What does the energy output have to do with it? I am talking about the responses variations with frequency at any given output. Yes the monopole excites a mode less because it excites the room less said:
Ignoring the fact that "pulse" tests are kind of meaningless since music is a continuous signal, I find the claim here - for dome tweeters - incredible. Don't forget that the energy density from 2 kHz - 20 Khz is ten times the energy density from 20 Hz - 2 kHz. Energy content has to be measured on a linear frequency scale not the log scale that better correlates to our hearing.
I don't think that you have the science right in your posts.
Hi Peter
I am sure you are right regarding the recording and mastering of CDs and playback gear, CDs can be made to sound really really good, but generally for me using anything I can remotely afford LPs just float my boat better.
I have tried quite a few DVD-A and SACD discs and players and LP to CD conversions at various bit depths (a good part of my income is derived from teaching folk about the process and I am in most things a digital kind of guy). In the end the CD just didn't compare to the other formats to my ears, basically I felt it lacked life. I have of course tried dual discs and played both SACD and CD versions.....result the CD lost each time.
But as you say the quality of the mastering etc is probably a limiting factor, in the end however I can only listen to what the music format supplier sells me and if the content of the CDs are inferior then that remains the problem.
I must say however I have had really good results via ripping files from CDs using MAX on my Mac and playing them back via an external DAC, this was far far better than any CD player I have had.....and strangely the sound was far better than playing the CD direct in the computer via too. But that is a whole separate thread.
I haven't given up on 16/44 format and I still seek to get the best out of it, it just doesn't bring the hairs on the back of my neck to attention, but I have far too many CDs to avoid it so any tips are always welcome
PS: I will say however I have got a couple of CDs where everything seems to be really sweet and peachy.
Cheers
Zero One.
I am sure you are right regarding the recording and mastering of CDs and playback gear, CDs can be made to sound really really good, but generally for me using anything I can remotely afford LPs just float my boat better.
I have tried quite a few DVD-A and SACD discs and players and LP to CD conversions at various bit depths (a good part of my income is derived from teaching folk about the process and I am in most things a digital kind of guy). In the end the CD just didn't compare to the other formats to my ears, basically I felt it lacked life. I have of course tried dual discs and played both SACD and CD versions.....result the CD lost each time.
But as you say the quality of the mastering etc is probably a limiting factor, in the end however I can only listen to what the music format supplier sells me and if the content of the CDs are inferior then that remains the problem.
I must say however I have had really good results via ripping files from CDs using MAX on my Mac and playing them back via an external DAC, this was far far better than any CD player I have had.....and strangely the sound was far better than playing the CD direct in the computer via too. But that is a whole separate thread.
I haven't given up on 16/44 format and I still seek to get the best out of it, it just doesn't bring the hairs on the back of my neck to attention, but I have far too many CDs to avoid it so any tips are always welcome
PS: I will say however I have got a couple of CDs where everything seems to be really sweet and peachy.
Cheers
Zero One.
gedlee said:
Then I assume you used high continous levels not likely to be found in music. I have measured dome tweeters that can play sines in the low impedance region* at 90dB spl continously for a minute without more than a tenth or two of a dB in thermal compression. I must search in my drawer for the results or do them again if you want exact conditions and results but it was thereabout. Feeding a 5kHz sine at 54V p-p (ca. 45W) for 5 seconds into a Accuton C23 raised the resistance by a factor 1.14. That equals aprox. 105dB spl. No one with normal hearing enjoys that kind of sustained levels at those frequencies.
* The measurements was done as a "worst case scenario" that is we played sine in the range where the impedance is a low and resistive as possible. Also obviously without any crossovers which improves not only HD and IMD of drivers but also improves upon the thermal behaviour.
We also measured some Seas alu-domes with ferrofluid and a Scanspeak 9700. The Seas was ok but 9700 compressed more most likely due to lack of ferrofluid in the gap and the silk dome that does not help with cooling of the VC.
Stereophile published a mesurement of thermal copression of a two way 7" speaker (I think it was) and it showed no compression to speak of using typical program material. The bassmid showed some compression though.
The stereophile measured average and not peak compression though.
I don't doubt that for some users a dome tweeter will thermally compress audibly.. but the debate on the forum from the "pro-driver-croud" seems a little off. The compression in the masteringstudio is a far worse factor when it comes to dynamic music reproduction.
Energy is what drives the room resonances and the outputlevel has little to do with it practically.
A monopole and a dipole excites mode differently on the axis but the dipole has way less contribution up and to the sides due to the figure eight dispersion. Also one must take into account the physcoacoustics when judging performance in room. A graph on paper does not tell the whole story.
I am aware that some standing waves may be worse (in the direction the dipole faces of course) with a dipole but overall there is better articulation with a dipole in the modal region than compared with a omnipole. Obvioulsy multiple omni woofer spread out in the room improves upon this... as would multiple dipoles.
Not at all. Music is not continous.. it CAN BE but then it is normally not played back at very high levels. We simply can not tolerate continous high levels in the high audio range. I'd consider a tweeter that can play 80-90dB continous and peaks/transients to 110dB without compression adequate. Anyone that doubt this, just play a 4V rms sine into a 88-90dB sensitive tweeter and see.
Incredible or not they are designed to handle 10kW transients. The spec says 5kW for safety. Obviously this is only valid in the high range, above 300-500Hz where conetravel are tolerable.
Don't forget that MUSIC does not contain ten times the energy in the topoctave. I assume you have done some work on this and done spectral analysis on typical music.
/Peter
Pan said:
A "little", and my results and experiences conflict with yours.
That 10,000 Watt tweeter sounds like a real winner. How do you even test for something like that? Thats almost 300 volts, RMS!!
You seem pretty attached to your position so I'll leave it there.
End of argument?
So tell me about it then..as you told me you were going to if I shared my findings.. otherwise it's just empty words and you who are talking about science and all..
It's one of the better, maybe the best yes. You build an amp or device that puts out that power of course.
Attached? I tell you about my and others findings/studies and I have not seen anything from you other than a slightly odd attitude.
/Peter
So tell me about it then..as you told me you were going to if I shared my findings.. otherwise it's just empty words and you who are talking about science and all..
It's one of the better, maybe the best yes. You build an amp or device that puts out that power of course.
Attached? I tell you about my and others findings/studies and I have not seen anything from you other than a slightly odd attitude.
/Peter
Pan said:
You are correct about my not giving any data. I didn't see the point. And my attitude is simply that these are the kinds of arguments that I'd prefer to stay away from. I've tried to be polite, I havn't called you names, but yes, I don't want to continue with this argument. Sorry.
The post just above is a classic example of where this will lead. Real useful comment!
Earl, it was a joke. The quote is taken from Yoda. It isn't all quite as serious as it seems. Audio is fun remember?
gedlee said:
Ok empty words then.
As for the dynamic rating of those drivers I mentioned I was wrong and I apolgize for spreading false information. The tweeters only handle 3kW, it's the midbasses that handles 10kW between aprox. 300Hz and 3kHz.
Really, you could easily have avoided this situation and I have only being straight and honest with you.
/Peter
I'd be interested in more information.
The compression test I've seen from in the NRC show little tweeter compression with a frequency sweep 20Hz-20K. The test are done at 96dB/1M & 101dB/1M and most of the time, the midwoofers show more compression than the dome tweeters.
For home audio, those are extremely high levels for a single speaker. If we are not seeing even a dB of compression at those levels, and the midwoofer is experiencing double or triple the compression of the tweeter, why is that the case?
The data I'm referring to is on the SoundStage site. Some of the speakers they review get measured in the NRC all using the same method.
The compression test I've seen from in the NRC show little tweeter compression with a frequency sweep 20Hz-20K. The test are done at 96dB/1M & 101dB/1M and most of the time, the midwoofers show more compression than the dome tweeters.
For home audio, those are extremely high levels for a single speaker. If we are not seeing even a dB of compression at those levels, and the midwoofer is experiencing double or triple the compression of the tweeter, why is that the case?
The data I'm referring to is on the SoundStage site. Some of the speakers they review get measured in the NRC all using the same method.
Kevin,
there is simply less power going to the tweeter than to the midbass.
Also small 5" woofers or midranges with small voicecoils typically suffer more from thermal compression than does a bigger midwoofers.
Good dome tweeter absolutely has enough dynamics for domestic use and for most program material and listeners.
Sterephiles findings and NRC's and mine all indicate this.
Some day I'll do some more measurements on tweeters but right now I'm busy with other stuff.
/Peter
there is simply less power going to the tweeter than to the midbass.
Also small 5" woofers or midranges with small voicecoils typically suffer more from thermal compression than does a bigger midwoofers.
Good dome tweeter absolutely has enough dynamics for domestic use and for most program material and listeners.
Sterephiles findings and NRC's and mine all indicate this.
Some day I'll do some more measurements on tweeters but right now I'm busy with other stuff.
/Peter
Kevin Haskins said:
Actually, to me, those are miniscule levels and maybe this is the source of the problem. A commercial theater has been measured - by myself - peaking at 125 dB SPL in the mid seats. Now to achieve a comparable SPL in a small theater one is going to be way above 101 dB/1M, more like 20 dB higher than that.
My test was not impulsive or swept, but a sustained noise level at about 100 dB @ 1 meter for the dome tweeter and 106 dB for the compression driver. The dome tweeter could not take the power level of the compression driver test without failure and at the lower level the compression driver showed absolutely no variations with time. It didn't even get warm.
The data is attached. Page one is compression driver and page two is a dome tweeter.
Clearly the smaller two way was having a lot more trouble with the power even at 6 dB lower than the compression driver. Now maybe these levels are more than you care about, or maybe this test is not to your liking, I don't know, but as far as I'm concerned no dome tweeter is going to survive my design criteria.
I am not interested in arguing about 3 kW dome tweeters any longer. Sorry.
This looks like an apples/oranges comparison again.
Everyone in my hifi club who is new to our gatherings quips that we play our systems bloody loud, but we've never approached anything close to those levels. Nor have I read about any audiophiles listening to their music at levels like those. This really seems to be the difference between the HT crowd and the hi-fi (stereo) crowd.
Everyone in my hifi club who is new to our gatherings quips that we play our systems bloody loud, but we've never approached anything close to those levels. Nor have I read about any audiophiles listening to their music at levels like those. This really seems to be the difference between the HT crowd and the hi-fi (stereo) crowd.
Thanks for the graphs.
Ok let's skip the 3kW discussion and talk about these tweeters you and I have measured.
My test shows that Accuton C23 has similar compression as your summa. I gave it 45W or so that equals aprox. 106dB at 1 meter and the thermal compression at 5 seconds was 0.6dB.
The dome tweeter you measured seems ok after all but obviously not on the level of your summa and the Accuton and Seas tweeters.
Care to tell what dome tweeter you measured?
edit: I assume your summa and the other speaker was measured in box with crossovers?
That gives them a possible advantage over the tweeters I measured since any impedance in series with the voltage drive serve to decrease the actual thermal compression. Possibly the C23 would have better thermal behaviour than your compression driver.
Sure, it's not really wise to compare drivers measured with different methods.. buit I think it gives some clues anyhow.
/Peter
Ok let's skip the 3kW discussion and talk about these tweeters you and I have measured.
My test shows that Accuton C23 has similar compression as your summa. I gave it 45W or so that equals aprox. 106dB at 1 meter and the thermal compression at 5 seconds was 0.6dB.
The dome tweeter you measured seems ok after all but obviously not on the level of your summa and the Accuton and Seas tweeters.
Care to tell what dome tweeter you measured?
edit: I assume your summa and the other speaker was measured in box with crossovers?
That gives them a possible advantage over the tweeters I measured since any impedance in series with the voltage drive serve to decrease the actual thermal compression. Possibly the C23 would have better thermal behaviour than your compression driver.
Sure, it's not really wise to compare drivers measured with different methods.. buit I think it gives some clues anyhow.
/Peter
I would agree.... we have different expectations.
What you are advocating is using full-blown pro-audio products in the home environment. Nothing wrong with that, I love horns and lots of dynamics but it won't ever sell. Average people don't have the space or the budget for seven loudspeakers of that kind of cost/size in their living space.
Also... I'd say 99.999% of the people building a home theater are not going to find the need to reproduce @ 125dB peaks. Nor will 2-channel guys need that kind of headroom to enjoy a loudspeaker. Otherwise, nobody would buy those twinkie little 4" full range drivers and come to the conclusion that they have reached audio nirvana.
What you are advocating is using full-blown pro-audio products in the home environment. Nothing wrong with that, I love horns and lots of dynamics but it won't ever sell. Average people don't have the space or the budget for seven loudspeakers of that kind of cost/size in their living space.
Also... I'd say 99.999% of the people building a home theater are not going to find the need to reproduce @ 125dB peaks. Nor will 2-channel guys need that kind of headroom to enjoy a loudspeaker. Otherwise, nobody would buy those twinkie little 4" full range drivers and come to the conclusion that they have reached audio nirvana.
JoshK said:
That doesn't make sense - movies don't play specific frequencies, they play soundtracks. This was a dB C measurement.
As far as levels, I know that I listen to a live performance DVD of Cream at a sustained level of 110 dB(C) - I measured it. These ARE NOT outrageous levels for those who like music at live performance levels. As background music I would agree on your position, but I want my system to perform at levels that I "might" want to achieve and sometimes do.
I used a lot of speakers for Home Theater before I made my own, and they either played loud or sounded good, but none of them did both. Thus I set out to achieve this task. Now if playing loud is not your thing then fine, but don't criticize me because its my design objective.
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