Of curse it works, Dimitri. As do other things which help the amp to drive a speaker as best it can. I've had it in my speakers right from the start. Some better UK louspeaker companies used to do it by default, don't know if they still do.
If you assume that one of the prime functions of a loudspeaker system is to be as linear as possible, it's not going to happen all ny itself, you need to help it do that.
Ok, could be.Dan you're going up against the folks who have literally written the book on this.
A survey of l/ f noise in electrical conductors
Dan.
If the compensation is a zobel type for the HF, I'm against that method. I can see a reason to do it, but I can see a better reason not to do it.
Two questions for people here involved in speaker's design:
1- What can be the measured effect of changing the foam surround suspension of a boomer (for an other brand). Change in F.R. ? Change of the peak at the Frequency where membrane begin to fractionate ?
2- How long and how (sinus, pink noise, what level) are-you doing the break-in of a speaker before measuring-it ?
Thanks for your answers.
1- What can be the measured effect of changing the foam surround suspension of a boomer (for an other brand). Change in F.R. ? Change of the peak at the Frequency where membrane begin to fractionate ?
2- How long and how (sinus, pink noise, what level) are-you doing the break-in of a speaker before measuring-it ?
Thanks for your answers.
Two compensations. Zobel for inductance (can be in two parts when (often) not linear, specially for tweeters) and motional (RLC)l for resonance frequency.
I am curious and interested to read your cons arguments.
BTW: i just found an article about this on Internet:
DIY Speakers Design Knowledge, Speaker Review, Loudspeaker: Zobel Network Design
Last edited:
Christophe,
Changing the foam surround for another type of surround can completely change the resonance frequency by changing the suspension stiffness let alone the mass which could potentially change the FR. There would be a series of changes. Termination of the edge of the cone would change with different material properties, it is a domino effect that would be hard to predict the end results.
Changing the foam surround for another type of surround can completely change the resonance frequency by changing the suspension stiffness let alone the mass which could potentially change the FR. There would be a series of changes. Termination of the edge of the cone would change with different material properties, it is a domino effect that would be hard to predict the end results.
Thanks, Steven. I was wondering if the spider was not the main 'spring' in the assembly, so the surround could have little influence on resonance frequency (apart added or reduced mass of the foam).
i was obliged to do this replacements on my boomers, and they, as you said, changed a lot their 'sound' both edge of their bandwidth. Breaking a fragile balance. I have to redo measurements now. Boring ;-)
i was obliged to do this replacements on my boomers, and they, as you said, changed a lot their 'sound' both edge of their bandwidth. Breaking a fragile balance. I have to redo measurements now. Boring ;-)
Last edited:
Good grief - would it be too much to ask, please don't take anything I say out of context.
You have just constructed a classic straw man argument.
My bad, Joe, I clearly misunderstood what you wrote (or else you are made of straw?).
Would you care to clarify what you meant when you wrote "What is the point of science if it seeks answers to the unknowable and unobserved."? I took it at face value, but you clearly meant something else.
I took that to be a question, despite the punctuation, perhaps I was wrong. (Maybe it was a statement, like "'What' is the point of science, if it seeks answers to the unknowable and unobserved.") I thought I offered an answer to your question, but it seems to have offended you.
Would you care to clarify what you meant when you wrote "What is the point of science if it seeks answers to the unknowable and unobserved."? I took it at face value, but you clearly meant something else.
I took that to be a question, despite the punctuation, perhaps I was wrong. (Maybe it was a statement, like "'What' is the point of science, if it seeks answers to the unknowable and unobserved.") I thought I offered an answer to your question, but it seems to have offended you.
Christophe,
It becomes a total of the two. You can actually have some surrounds that are stiffer than the spider depending on what spider was used. Some thick rubber surrounds can be very stiff. The foam is more than likely one of the lowest in flexural modulus. I would have tried to obtain the original surround if possible. It could change the VAS and your enclosure size requirements.
It becomes a total of the two. You can actually have some surrounds that are stiffer than the spider depending on what spider was used. Some thick rubber surrounds can be very stiff. The foam is more than likely one of the lowest in flexural modulus. I would have tried to obtain the original surround if possible. It could change the VAS and your enclosure size requirements.
Yes, of course. No way to find the original surround and my boomers are no more in catalogs
I hope i will be able to make a miracle, but such a hard work, as the crossover is at the limit for the size of the membrane. (12", 1500Hz, go figure !)
Last edited:
I'm thinking to my son's heritage. At 70, i wonder each new day for me.
Beyma, if i remember well :-(
As they do not seem to use foam any more, I imagine that, if I can find the original surrounds, they will be as old as mine, so turn in powder in seconds or minutes.
I'll see what I can find. At the same time I don't understand why the engineers who produced all of these foam surrounds didn't understand UV blocking chemistry that would have kept these foam surrounds from doing anything but change color! Probably would have cost a couple of pennies more adding that to the pigment. At the same time the most stable color is always black.
Oh thank-you Steven.
I'm not sure it is not an effect of humidity on the foam. I can see the same kind of damage even with foam in enclosures protected from light. See the foams used for acoustic damping in Koss electrostatic headphones, as an example. It turn in oily powder with years. And they are not submitted to any movement.
I am always surprised how long foam is lasting with no visible change, and how fast it deteriorate all of a sudden.
I had took the precaution to paint my surround both side with silicone oil, to isolate them from air, and they were ok during > 30 years. Not so bad ?
No offense, and yes I clearly meant something else.
I was talking about the very motivation behind science. Of course, science is connected with curiosity - but that curiosity has a trigger - such as the sickness of a friend at a young age led you into science as to find answers. This is noble and proper. Ask people who ended up in science careers and you will find this pattern.
My point is that we can not disconnect science from the human experience, in fact that, as I said, the human experience was the starting point for many of us. My love for music, my love for my Father who died sadly young and was buried on my 23rd birthday - that I ended up in a similar profession to his and so on.
Of course we want to know the unknowable and chase stars - that goes without saying. And I am happy and comfortable that we shall never know it all - that it is endless.
Cheers, Joe
PS: Esperado's byline pretty much says the same thing: “The Only Source of Knowledge is experience, everything else is just information.” ©A. Einstein
Last edited:
So nice from you, Steven, but don't worry. I have changed yet the surrounds, no way to ensure an other brand will be better or even different from my new ones.
I will measure the result, and if there too much a peak around 1500 Hz, i will buy new boomers.
For the bass, not a problem to tune my vents according to the changes. and change the crossover frequency with my big sub.
But it is a lot of work to tune a two way enclosure with a horn for medium/treble and I'm more lazy than 30 years ago ;-)
I had spend six month at that time to fix the respective levels of the two ways, everything change at +- 0.2dB.
- Status
- Not open for further replies.