If this is true as I believe I wonder if this cone material topic has already been discussed at length in other threads
There are so many questions I would like to ask
For instance about how material properties can change with age
As I said previously I have had my portion of bad luck with two mid domes about 40 years old
Same part number and properties so different that is surprising
I have nothing about cannibalizing old speakers
Some units can be good even for today standards
But they should take a little care of matching them for frequency response and TS parameters and impedance
Recycling done right 👍
About the shape I believe that when a concept is sound it could be also scalable
For instance design and build a midrange cone
Then scale it up in size to make a woofer and down to make a tweeter
All with same shape
There are so many questions I would like to ask
For instance about how material properties can change with age
As I said previously I have had my portion of bad luck with two mid domes about 40 years old
Same part number and properties so different that is surprising
I have nothing about cannibalizing old speakers
Some units can be good even for today standards
But they should take a little care of matching them for frequency response and TS parameters and impedance
Recycling done right 👍
About the shape I believe that when a concept is sound it could be also scalable
For instance design and build a midrange cone
Then scale it up in size to make a woofer and down to make a tweeter
All with same shape
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Everything wears out, also speakers. I got speaker drivers that are 60 years old that still work close to spec, but that is not a guarantee, because most will detoriate and change spec. I measure all speaker drivers older than 10 years fully before i will use them in a build because of that.
Might look right but it's difficult to make it sound right. Domes, inverted or not, don't have the type of controlled 'breakup' needed for good sound. You have to operate them as 'pistons' and then deal with HUGE breakup just above the passband.
About the only advantage of a dome is you have to use a large voice coil so it looks (and IS) expensive and has slightly higher power handling, slightly better compression bla bla. NB I said slightly. 😊 Alas, the requirement to operate pistonic also means the bandwidth is severely limited.
You can certainly move between Mid & LF with the same shape but a HF unit is too small to take that scaling. You need a minimum voice coil size to have sensible power / signal handling. Fortunately, HF units can be domes and operate mostly pistonic.
KEF units of that era will have 'paper' voice coil formers and a B139 would be rated at 50W. It's quite easy to damage a KEF bass unit of that age as they were allowed to bottom out at high level and the paper formers don't like that. However, KEF were early adopters of plastics for cones and the other stuff which affect sound don't change much. But they won't survice teenage party use.
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I got a Kef Chorale speaker that is at least 55 years old and outside the crossover caps is fully original and functional. The grills are old and disuty, but even those are still intect. The B200 woofer and the Seas T27 tweeter are both in perfect shape.
I do also use some old Philips 9710M8 from 1969 in a certain setup, and altough they are probally not to original spec anymore, they still sound wonderfull good in big cabinets driven by a small wattage amplifier
But at the same time i got some B&W DM 603 from 1998 where the woofers are shot, they were not stored in good condition, and are rotted away. I can't even restore those anymore. The Kevlar mid is ok, and the tweeter is damaged due to a shot crossover...
So it all depends on the build quality and how well the speakers or drivers were stored. I would test those old KEF woofers extensivly before i do anything with them, even before i start to design a cabinet for them.
I do also use some old Philips 9710M8 from 1969 in a certain setup, and altough they are probally not to original spec anymore, they still sound wonderfull good in big cabinets driven by a small wattage amplifier
But at the same time i got some B&W DM 603 from 1998 where the woofers are shot, they were not stored in good condition, and are rotted away. I can't even restore those anymore. The Kevlar mid is ok, and the tweeter is damaged due to a shot crossover...
So it all depends on the build quality and how well the speakers or drivers were stored. I would test those old KEF woofers extensivly before i do anything with them, even before i start to design a cabinet for them.
I don't want to break open the packaging just to test them, it would be ludicrous. The originals in the Concertos functions very well and sounds lovely warm and inviting not like modern speakers. Besides, I turn the speakers every six months by 180 degrees just to ensure the cone does not sag. the voice coil is wound around a non ferrous metal tube as far as I can tell. The newer B139 could be a paper composite which is clearly identifiable in the bass radiator of the Cadenza. But the two B139 actual drivers are completely different in construction as well as magnet size, cone size, height, surround and spider and pigtails. I don't really care much about that, it is about the sound. I also have a single T27 tweeter spare of that time, completely sealed in original packaging, but had to replace one 40 years ago when I burnt the voice coil listening to Bach on Moog, the moog sound was probably constructed of square waves and burnt out the tweeter coil. I have since avoided electronically generated music at all costs. I cannot stand auto-tuned voice either it is just unpleasant.
Thank you very much again I have to say that since i got an impedance meter i can see things of which i have never tought before
i think i have a sort of cannibal instinct in audio My reasoning is the follow
Everything starts from a transducer Speakers famous for great sound must have great transducers
The new products have reached prices out of my reach I have seen small 2 ways bookshelves at 5kUSD/pair
So i was looking at the vintage speakers and the drivers they mount
But now i am quite worried
For instance i like very much the drivers of the dq10 in particular the philips and the dome midrange
it is difficult to test them before buying Almost impossible
maybe it they are packed well who knows Pretty soon i hope i will be able to record a frequency sweep that together with an impedance sweep and TS parameters calculations should provide a better picture of a driver
That is a real problem that anyone will have, besides you cannot trust comments here either because you may hear and appreciate something totally different from whoever reviewed them. In the distant past you could read a review of some equipment, then go in to a distributor and listen and make up your mind. Nowadays you are compelled to look at a picture on the internet and buy on-line, hoping that what you read conforms to your expectation. If not you just got yourself another pair of drivers that you don't know what to do with.
what about using them with a very steep digital xover ? for me it is important that at least in a range they measure very good
i am starting to be puzzled by all discussions about passive xovers So many variables And just one high end cap can cost like an entire digital stereo xover
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very interesting Thank you very much Again I have learned more about speakers technology this week than the last ten years reading magazines
personally also the purchase of an instrument has been an eye opener
My uncle uses some electric stimulator to cure his leg
I'm trying to convince him to let me measure the impedance of his leg 😏
thanks a lot again I have checked and actually i bought these things about 5 years ago
But the important thing is that i have learned the lesson I will never buy old drivers again without testing them
i have still to set up a rig to measure the freq response to be fully operative
i would like the Dayton Audio usb calibrated mic Is around 100 euro I will ask around about its quality
Even though the driver technology is quite similar now than hundred years ago, the advancements in materials and manufacturing tolerances and all means that there is probably only a handful of old drivers that are worth buying, and rest just aren't. Unless you are restoring some particular speaker you'll likely find brand new driver with similar price and be sure it will work the next x years.
thanks a lot again What i find surprising is that in all discussions about vintage speakers this extremely important issue of parts aging is never mentioned
On the basis of my own experience i can say tat aging could make a pair of drivers pretty much unusable because their parameters have changed from the original specs in different way
I am in contact with an audio dealer who has bought many old drivers from a collector
He says that buyers are usually more concerned with the look of speakers than with their electrical performance
For me this is mind blowing They are not furniture or ornaments
Look can be deceiving What looks similar can perform quite different
and what looks good it does not mean that sounds also good
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Yeah, it doesn't matter if it's best in the world, if it's not working... It's just not worth it unless it's something you must have from nostalgic reasons for example, or if it's super low cost good deal and indifferent if it works or not. Because, similar or better performance is likely available brand new.
Look and smell and other values can be very important to people, and for this reason be very careful whose advice / opinion you value because their reasons might be different than yours. In my narrow view 80% of people don't care much about the sound and listen what ever they happen to have, that looks cool or is practical. 80% of the rest likely think they do it for good sound but still might not know what is good sound and what it calls for and buy the trendy gold nugget looks and status than sound, because everyone else does this it must be good, right?
While there might be little difference in sound between two very good suitable units, it's very likely that difference is due to expectation bias. Example, the expensive vintage unit must sound better, because I saved for it years and finally found it, right, the modern alternative doesn't even interest me, it's invisible. Nothing would be better in that case, and why not, do what you please, what ever makes one happy 🙂 It might be that some particular old unit is better than anything made after, but if it is why no-one is making new version of it? Or are they?
So, I think there is both power and weakness hidden in how we perceive things, if you lust for something nothing else can substitute. But if you can think it through rationally, you'd likely be more than happy with something more rational. I think that I could either drive my expectation bias, or be driven by it, and the difference is whether I know it exists and affects perception.
Look and smell and other values can be very important to people, and for this reason be very careful whose advice / opinion you value because their reasons might be different than yours. In my narrow view 80% of people don't care much about the sound and listen what ever they happen to have, that looks cool or is practical. 80% of the rest likely think they do it for good sound but still might not know what is good sound and what it calls for and buy the trendy gold nugget looks and status than sound, because everyone else does this it must be good, right?
While there might be little difference in sound between two very good suitable units, it's very likely that difference is due to expectation bias. Example, the expensive vintage unit must sound better, because I saved for it years and finally found it, right, the modern alternative doesn't even interest me, it's invisible. Nothing would be better in that case, and why not, do what you please, what ever makes one happy 🙂 It might be that some particular old unit is better than anything made after, but if it is why no-one is making new version of it? Or are they?
So, I think there is both power and weakness hidden in how we perceive things, if you lust for something nothing else can substitute. But if you can think it through rationally, you'd likely be more than happy with something more rational. I think that I could either drive my expectation bias, or be driven by it, and the difference is whether I know it exists and affects perception.
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I use old drivers when i can find them cheap, those Philips drivers i spoke about above were a part of a small collection (including Audax tweeters, and various Seas and Philips cone drivers) that i got for about 100€, all worked stil quiet good when i bought them and still worked the last time i checked them.
But i will never pay a lot of money for old drivers, or think they are better than new. It's just i like to recycle things, and when an old driver is still fit the purpose i will use it. Those Philips are my workshop speakers, and are amped with a small SMSL amp fed from a laptop mostly (internal soundcard). There is mostly noise there and they are perfect as background music speakers. They sit in old subwoofer cabinets that were not build for it but work wonderfull well (pure luck). I did build them because i had the parts laying arround and i needed no budget workshop speakers...
But i will never pay a lot of money for old drivers, or think they are better than new. It's just i like to recycle things, and when an old driver is still fit the purpose i will use it. Those Philips are my workshop speakers, and are amped with a small SMSL amp fed from a laptop mostly (internal soundcard). There is mostly noise there and they are perfect as background music speakers. They sit in old subwoofer cabinets that were not build for it but work wonderfull well (pure luck). I did build them because i had the parts laying arround and i needed no budget workshop speakers...
thank you very much for the very kind and valuable sharing of important information
forgetting vintage now the problem is always to get an idea of the sound quality of a transducer
can we agree that there no practical measurements usable ? that the only way is like Mr Olson says to mount them on a baffle and listen ?
not very scientific but science has limits
and of course the same will apply to coils caps resistors cables binding posts ....
and there is another question ... listen to what ?
forgetting vintage now the problem is always to get an idea of the sound quality of a transducer
can we agree that there no practical measurements usable ? that the only way is like Mr Olson says to mount them on a baffle and listen ?
not very scientific but science has limits
and of course the same will apply to coils caps resistors cables binding posts ....
and there is another question ... listen to what ?
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I don't agree at all, all is measurable. You just need to know what to look for, and therefor you need to study speakers and how they work. It's not magic or rocketscience at all. It's all physics and math.
I see Let me rephrase I cannot select a driver only looking at its datasheet but other measurements must be carried out ?
i guess i have to trust someone else lab work then
I cannot measure CSD or group-delay vs. frequency (actually i do not even know what it is group delay. Just found mentioned here http://www.nutshellhifi.com/Ariel.html )
However i remember Lynn Olson speaking about drivers selection also using listening tests I cannot find those lines anymore
i would study about arbitrary waveforms specifically designed for drivers testing
like square waves They usually tell a lot And usually it is not good With drivers With some exceptions
https://quad-hifi.co.uk/collections/electrostatic-speakers
i think that the problem with Quad is that they can do this only up to a certain SPL I guess not that much Maybe only 90dB
in the end i like CSD and multitones response Settling time and IMD
i guess i have to trust someone else lab work then
I cannot measure CSD or group-delay vs. frequency (actually i do not even know what it is group delay. Just found mentioned here http://www.nutshellhifi.com/Ariel.html )
However i remember Lynn Olson speaking about drivers selection also using listening tests I cannot find those lines anymore
i would study about arbitrary waveforms specifically designed for drivers testing
like square waves They usually tell a lot And usually it is not good With drivers With some exceptions
https://quad-hifi.co.uk/collections/electrostatic-speakers
i think that the problem with Quad is that they can do this only up to a certain SPL I guess not that much Maybe only 90dB
in the end i like CSD and multitones response Settling time and IMD
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you would have to do extended listening tests to verify there is a correlation between reproduction of square waves and what you like in sound reproduction - or what you would classify as quality.
otherwise it's just an arbitrary rather "visual" attemt to simplify an (unverified) concept of "truth".
don't fall for the false and cheap explanations!
by the way: a measurement microphone, a soundcard/interface and REW are not very expensive and allow to make CSD and group delay graphs and much more.
It's incredibly instructive to use these tools.