Well, you state it as a fact that if a speaker measures correct, it also reproduces correct.....I wish it was that simple....there are many ways of getting nice looking measurements....but they all sound different....a wise man once said that if you can get the same result with less components, it will sound better, and thats a fact.
tinitus said:
Your right about the amount of information on cheap and average disc's. Stuff like the sound engineer mixing two different sessions, or a claustrophobic presentation, hyped treble, improper level settings and many other examples of mixing/recording gone bad that go on to make poor recordings. Then you playback a decent recording and realise that it isn't the speakers at all but someone botched the recording process. The point I'm making is not questioning the amount of information on a disc but rather the quality. This is easily highlighted through an accurate speaker.
It probably sounds like I'm not looking for musical enjoyment but rather I want something that allows me to analyse the recording however that couldn't be further from the truth. Accuracy is enjoyment for me and enjoyment that can only be provided by an accurate playback system, a side effect of this is that you notice the stuff that is wrong and its easily identifiable on some discs - again not the speakers fault but the recordings.
tinitus said:
You'll also notice that I've been deliberately vague as to what exactly is an accurate speaker. I've tried to portray it as something that is simply an 'ideal' and not a set in stone method. I've said that it follows the source as closely as possible and this implies that the loudspeaker measures as best as possible in all regards.
The crux of the matter is that an accurate loudspeaker isn't just about simply getting a +/- 0.5dB response or a THD figure of 0.3% from 50hz - 40Khz etc. A truly accurate speaker is impossible at this stage and there's still subjectivity involved but I place far less emphasis on that than most. An example of this subjectivity would be how a loudspeaker sounds surprisingly different using two XO schemes that measure almost identically on many aspects. Generally though, when your designing a loudspeaker and calculating the XO point you measure the distortion figures and on/off-axis response or get data to that effect and design around best case scenario's that fully exploit the strengths of each driver and the band that it covers whilst also mating well with the other drivers and improving areas such as power response etc. again this tries to adhere to the accuracy and measurement thing rather than listening to what sounds best.
I can trust my ears when listening but I can't trust my judgement when making critical calls as its all too much guess work based on subjectivity and this is the same reason why I can eat chips 3 days in a row and then get fed up with them and not bother for another week or so, whilst other times I can't stand to eat them for weeks on end, its all down to how I feel at the time.
My original point was that accurate speakers are desirable and its clear that there is no such thing as truly accurate otherwise there would only be one pair of speakers being made right now but rather varying degrees of accurate or even in-accurate if you like. I prefer to try to get as close as possible to this ideal as I possibly can.
Another point I made was that we should place far more blame on recordings than we currently do. It seems to me that the loudspeaker often takes the wrap for a poor recording.
Sound better? Or measure better? Subjectivity or objectivity? 😀
Its great to see the British unfolding celebral (the ones that tought loudspeaker science), the Danish unfolding sensual (the ones that progressed high end drivers a lot).
And its funny that the Japanese fathers of sensuality in Audio have an affection for LS3/5A and Tannoy too.
I guess we are all much closer than we think we are.
And its funny that the Japanese fathers of sensuality in Audio have an affection for LS3/5A and Tannoy too.
I guess we are all much closer than we think we are.
The shielding magnet is generally smaller in diameter and thickness than the main magnet. It is stuck 'outside' the rear plate and is obviously smaller in size compared to the main magnet. The picture seems to show two magnets stuck directly together. This would mean that they are in the main magnetic circuit . Higher sensitivity (?) or higher flux required in this design.
Cheers.
Cheers.
No, you should look closer at picture from Per - poleplate is between the two magnets
And Per, this way it has to be oriented rewersed - that means both magnets will have same polarity against the poleplate
It may not be as effective but it will help the other magnet to saturate inner polepiece
And Per, this way it has to be oriented rewersed - that means both magnets will have same polarity against the poleplate
It may not be as effective but it will help the other magnet to saturate inner polepiece
Per Nielsen said:
Hmm..... I'm wrong ?
I'm afraid its you who are incorrect.
You do not get any extra magnet power with "normal" polarity,
due to magnetic circuit saturation effects you actually get less.
With reverse polarity you do get a little more, perhaps 1dB.
This is because the reverse field concentrates the main field.
(That is the main field occupies 2pi instead of 4pi space)
🙂/sreten.
why not put it near to your television set and see what it does to the picture? you should be able to get it much closer than a normal driver if its the shielded version . . .
looks like the shielded one to me as the extra magnet is behind the back plate of the driver, i dont see why they would have done this instead of putting the magnet inside the magnetic circuit, seeing as they are making the drivers from basic parts anyway.
looks like the shielded one to me as the extra magnet is behind the back plate of the driver, i dont see why they would have done this instead of putting the magnet inside the magnetic circuit, seeing as they are making the drivers from basic parts anyway.
sreten: I have being saying right from the start they are jouinded together to increase the db!!! So please stop posting anymore disutions about if it is a sheilding magnet or not! I know it's not!! The question whas the expectet increasement in dB not a sheilding question!
Im proberly wrong on the polarity I dont know anything about this, and It really dosent matter and I really dosent care about that because it not me that does the job on putting the magnet on
Im proberly wrong on the polarity I dont know anything about this, and It really dosent matter and I really dosent care about that because it not me that does the job on putting the magnet on
Per Nielsen said:
Hmmm.......
you don't seem to be interested in what exactly is going on.
FWIW the increase in sensitivity is related to how badly designed the
magnetic circuit is in the first place before the magnet is added, the more
leakage flux prior, the bigger the increase post adding the bucking magnet.
An increase of more than 1dB IMO is highly unlikely.
🙂/sreten.
Sorry sreten im very interrested... but not in a debate about it being a sheilding or not.... when I have pointed out Its not a sheilding after shinobiwan har rasied that question I really don't see why that debate must go on
As I recall this was my answer and that would be enough!:
No the magnet is not there to cancel magnetic strays
That kind of clear answer should stop a very unimporten debate if it is or is not a sheilding!!! I know its not a sheilding so there fore no more people posting their very "cleaver" answers about its a sheilding or not!! -havent any one noticed i have written about it sounds like it's 2 db higer?? still the debate runs on...
Now I have ****** up my tv just to prove and to stop this debated about something totally useless...
The xt is being held about 40cm from the screen!!!!
If someone accidently should be color blind and still wants to debate sheilding.. I can tell you it has made a huge blue dot on a green background!!!
Ps. shinobiwan it really wasen't your fault, im glad people ask questions, it was other people that just kept your question going, even if I would say I had pointed out its not
As I recall this was my answer and that would be enough!:
No the magnet is not there to cancel magnetic strays
That kind of clear answer should stop a very unimporten debate if it is or is not a sheilding!!! I know its not a sheilding so there fore no more people posting their very "cleaver" answers about its a sheilding or not!! -havent any one noticed i have written about it sounds like it's 2 db higer?? still the debate runs on...
Now I have ****** up my tv just to prove and to stop this debated about something totally useless...
The xt is being held about 40cm from the screen!!!!
If someone accidently should be color blind and still wants to debate sheilding.. I can tell you it has made a huge blue dot on a green background!!!
Ps. shinobiwan it really wasen't your fault, im glad people ask questions, it was other people that just kept your question going, even if I would say I had pointed out its not
Attachments
Per Nielsen said:
Now why would you go and do something stupid like that? 😀
Well then..
..please refer to this page for diagrams:
http://ldsg.snippets.org/motors.php3
Lets think about the driver in general.. This ring radiator is all about creating sound from its "surround". Essentially then this is a driver that principally relies on excursion for operation - not just to extend low freq. response. (i.e. the surround IS the diaphram.)
With this in mind the VC is probably an OVERHUNG VC (..as opposed to an underhung VC - which most tweeters are). Overhung VC driver's have longer VC's and so it is more difficult (perhaprs impossible depending on the design) for them to extend out of their gap - which is why they are preffered for higher excrusion drivers. (..note however that they are usually less linear then underhung VC's operated within linear excrusions - so there is "give and take" here.)
Now then, most good overhung drivers use extended pole-pieces - and I'd bet that this driver is no exception.
An extended pole-piece is used to increase the gap (length) and allow for a bit more extended VC excursrion - both forward and backward. Unfortunetly the field becomes less powerfull/forcefull at these "extensions" and as a result the field is less symetrical. What this means for an overhung VC is that more of the VC is in the gap even if not all of it is as linear because of power (gauss) loss at the ends of the gap (i.e. the area that is principally less symetrical).
Additonally, we also need to consider HOW the principal magnet is used. Note that the backplate, the portion that is on the rear of the magnet, extends the magnetic "circuit" (south pole) to the become the outer "edge" of the magnetic gap. Of course the north pole is forward of this - attached to the front plate which is then attached to the pole piece and creates the inner "edge" of the magnetic gap. (.. and of course the VC move in-between these two "edges".)
What we need to note here is that their IS a magnet forward of the backplate and there is NOT a magnet rearward of the back plate. This means that there will be some additional force foreward of the backplate in comparison to reward of the backplate. This has little meaning with an underhung VC, but with an overhung VC their is a bit more force foreward of the backplate that will interact with the VC.
The net result with an overhung VC is that the forward gap is more powerfull exhibiting greater control over the VC then the rear of the gap. (..i.e. the rearward "stroke" of the VC is less linear.)
Now lets add a magnet to the back plate of this driver. In particular lets add a magnet with dissimilar poles - in this case a north pole on the new magnet added to the back plate which is the south pole of the principal magnet. (.. the reverse is a obviously for reducing stray magnetic fields.)
The addition of the magnet to the back plate adds SOME strength to the back plate. With an underhung VC then the strength added to the south pole/back plate is more a factor of the new magnet's gauss/power. As mentioned, sometimes this can result in as much as 1-2 db's of gain (depending on the driver).
With an overhung VC however, the magnet interacts more with the VC then just via the backplate because the VC is longer and extends out of the gap. (..just like it does forward of the gap with the principal magnet.) Now it might not be much more force overall (..because the magnet is effectivly much further away from the VC), BUT force is applied over a greater length of the VC. Furthermore that force is now more "balanced" (for lack of a better word) - in that the additional force forward of the back plate is now represented with addtional force reward of the back plate. This should add some linearity at normal excrusions. More importantly however, it should add a fair bit of linearity at increased excursions. (i.e. the rearward "stroke" of the VC is now similar in linearity to the forward "stroke".)
Man that's a lot of typing up there. I just wanted to interject that you can fix most CRTs that have been damaged this way by degaussing them. You can do this with a degaussing coil (like a computer CRT monitor has) (Don't know it would work to put a computer CRT up to the TV and degauss the monitor, if it would degauss the TV as well? )
OR you can do what I have done (had to do) a few times. carefully, slowly, move a magnet in circles, from close and slowly moving backwards away from the TV, and you may be able to neutralize the magnetic field you JAMMED on there with the speaker magnet.
BTW, keep that magnet away from the cassette tape collection ok? HTH
/edit: you may have to give it the treatment several times if the imposed field on your TV is very strong. I have not yet had a TV I couldn't fix good enough to enjoy watching again this way.
OR you can do what I have done (had to do) a few times. carefully, slowly, move a magnet in circles, from close and slowly moving backwards away from the TV, and you may be able to neutralize the magnetic field you JAMMED on there with the speaker magnet.
BTW, keep that magnet away from the cassette tape collection ok? HTH
/edit: you may have to give it the treatment several times if the imposed field on your TV is very strong. I have not yet had a TV I couldn't fix good enough to enjoy watching again this way.
Excellent scott just the explaining that was needed....
I think i remember it is overhung I disassemble one a couple of years ago http://www.diyaudio.com/forums/showthread.php?s=&threadid=10890&highlight=
stocker: don't worry was just a joke would never have done it if I hadent had a degause coil just by the hand😀
I think i remember it is overhung I disassemble one a couple of years ago http://www.diyaudio.com/forums/showthread.php?s=&threadid=10890&highlight=
stocker: don't worry was just a joke would never have done it if I hadent had a degause coil just by the hand😀
ups wrong link to the pics
http://www.diyaudio.com/forums/showthread.php?s=&threadid=10890&perpage=10&highlight=&pagenumber=3
http://www.diyaudio.com/forums/showthread.php?s=&threadid=10890&perpage=10&highlight=&pagenumber=3
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