That is the key question, indeed. The answer is both yes and no, but more no than yes. Sorry if that sounds like I am obfuscating, I am not meaning to.
A current source fixes the current (not the voltage) and that means you have a finite amount of current. Now vary that current (less) through the voice coil at Zmax (the max motional impedance) up to the fixed amount, and you get to a certain point where Re can be infinite, where the total series impedance, including the driver itself, will have no effect, but the current at the motional impedance will control the damping. We are of course talking about sealed boxes, it is more difficult with vented alignments. It is done with passive components and it does not work when using a voltage source, because then you have no control over the current.
I don't want to say much beyond that, but it does work and can even be done in modeling with Bogdan's SoundEasy. But the presentation and wording of the argument has to be carefully prepared, proof-read by some key people. BTW, two of them is in the School of Physics Dept of your own Monash University down in your Melbourne city.
What is so interesting is that the output SPL is always proportional to the current. This can only be confirmed by the change in current and measuring that change. It cannot be done in an absolute sense because measuring the accuracy of absolute efficiency is a real challenge even to get to within 1dB. But Stuart Wurcer's question (challenge?) that proportional change on the electrical input of 0.1dB purports to an exact change of 0.1dB of SPL measured via a microphone will need to be proved true. SoundEasy modeling confirms it already and presented that evidence several times in the lounge (u-know-where) and was ignored until Stuart actually tweaked to what was going on. Also, this current vs SPL also applies at the peak motional impedance (Fs or Fb) and if you can control the current there and to either side in a precise way, you can make the output impedance of the amplifier irrelevant under current drive, but less so under voltage drive. It reverses popular notions, but then studying what the current does can lead to weird and wonderful things.
BTW, the Elsinore thread is more about supporting Elsinore builders than becoming a thread where theory takes over. Yes, there is a twin aspect to the Elsinore Project, where understanding current is important, but mostly just pure DIY, where those who make the effort can make a speaker that makes them happy, puts a smile on their faces.
If you ever come up this way, my front door is always open. I don't say much, I just play music for my visitors and that says enough.
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Thanks, much appreciated. I was hoping that you would read my earlier post when I mentioned you? I have a friend here locally, his name is Morris and he is a real no-nonsense kind of guy, crusty and very knowledgeable. I mention him because he is vetting what I am doing and keeping things on the straight and narrow. So I only mention this as I can't get away with anything sloppy and what I am working on (you will see it in the end) be logically tight and clean. I know that you will appreciate that.
I have come up with a central argument, something that is so good, I know you will like it. I can't yet go into it, but a single sine wave where the current phase angle is not zero, shows up measurable distortion on the current side and IMD that can be captured on the acoustic side. What's more, there is a mechanism that absolutely explains it. But it has to be perfectly presented. But this kind of discussion will not be in the lounge and not on this thread here. I have wisened up greatly.
Cheers, Joe
I am not dead yet. I will always be working on something.
Checking the basic schematic Joe I don't see it "breaking a lot of new ground"
Local anode-grid feedback / bootstrapping in the output stage? Done by McIntosh ages ago...
Maybe a large output transformer step down ratio to reduce the gain? Sorry it's not new let alone "ground breaking".
With Unity Couping done by McIntosh I see exactly the same outcome: local feedback in the output stage by dividing anode and cathode loads in halve, putting quite some strain on input/driver stages.
Not to mean trolling, but with this schematic you really are challenging your "trolls".
By the way: check your drawing. Curious what will happen with the upper output tube when you wire it as drawn...
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Knew that kind of comment was coming, so no other comment than this: Not everything has been revealed. If you saw some of those resistor values, you would think otherwise. It's not a McIntosh copy, or else I would have copied McIntosh and I did not. And oh boy, didn't show you the power supply.
The word "new" seems the colour RED to some people. I know what is new and not.
End of comment.
I didn't say it is a McIntosh copy; your schematic shows some similarities.
There are different ways to reach a goal; yours are not so different as you suggest.
"New" OK.....
"breaks a lot of new ground"....mmm let's see.
You did not correct your schematic; there is a fatal mistake still.
There are different ways to reach a goal; yours are not so different as you suggest.
"New" OK.....
"breaks a lot of new ground"....mmm let's see.
You did not correct your schematic; there is a fatal mistake still.
Are you just asking the trolls to come out of their bushes, or are you actually going to tell us what is new about your circuit?
Hi Hugh. Wow! Good to hear from you, hope you are keeping well. Many of us are starting to have age problems, mine is arthritis, but for now not in my hands. If you ever come up this way, please do tell.
Cheers, Joe
Yes, there was a CAD typo. Did anybody else spot it? The bottom tube was OK though, so it was kind of obvious. Never were the best CAD operator around.
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One can see the bones of Allen’s work in the map Joe posted.
I look forward to further developments.
dave
OK, I found the problem, after looking at wiring diagram and my crossover I found I wired zobel the wrong way. Will try to rewire it tomorrow I just want to enjoy the sound coming out without zobel for the rest of today... Thanks Joe for designing this magnificent speakers... Here is a picture of my setup will post some more photos when Im done...
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Absolutely!
The "Vacuum State" guys are still carrying on.
I owned the domain name until I eventually passed it on to Hanni, his wife, around 2013 and made sure the registration was fixed for another ten years. The website is still there and if anybody wants anything made, Thomas is still there to do it. So guys, you still want Allen's designs, then you can still get them. They can still be made.
Oh, I won't get a cent out of it. Zilch!
Duratex experience
I painted my with Duratex, paint is great for something that gets transported around alot... But if I would be painting speakers again I would not go with Duratex, this thing dries quicker than I can apply paint so my speakers after first coat with white foam roler were like sand paper my first thought was dust build up and cleaning. But there was something that I like about this paint just not for speakers. So I did the method with plastic bag to get it a litle bit smoother. I was reading later that the thiner version for spraypainting works better but dries a little longer. But this paint has a lot of texture when it dries...
I painted my with Duratex, paint is great for something that gets transported around alot... But if I would be painting speakers again I would not go with Duratex, this thing dries quicker than I can apply paint
so my speakers after first coat with white foam roler were like sand paper my first thought was dust build up and cleaning. But there was something that I like about this paint just not for speakers. So I did the method with plastic bag to get it a litle bit smoother. I was reading later that the thiner version for spraypainting works better but dries a little longer. But this paint has a lot of texture when it dries...
Yes, there was a CAD typo. Did anybody else spot it? The bottom tube was OK though, so it was kind of obvious. Never were the best CAD operator around.
Had to stare at it for about 5 minutes. Seems my brain was dubbing in the correct connection.
Hope you have these available when I visit, curious I become.
OMG.. Track 3 sounds amazing on the Elsinore's!
As that song started, it grabbed my attention and the hairs on my arms stood up...
I believe these baby's are warming up nicely. So amazingly happy with how full and complete they sound!!!
Have to admit, I don't believe I have heard the entire sound spectrum like ever before.
Another strange, very strange thing... At low volume, the room is filled with glorious sound. Every frequency is crystal clear. At low volume I feel like they are playing MUCH louder than they really are. Absolutely does not need a sub for any reason.
Back to the music...
scottme,
I am not sure if it will work in your case, but I have repaired small cracks in rubber surrounds using contact adhesive type glue and very thin polythene. I applied it from the rear side of the cone, using as little glue and polythene as possible. For glue IIRC I used UHU glue.
Amazon.com : UHU ALL Purpose Adhesive 35ml : Office Products
My reasoning was that the repairing material should be very low mass and add minimum change to the compliance of the existing surround; basically a patch that restores the air seal allows the front suspension to function as closely as possible to what the manufacturer intended.
If you want to try out, it's better that you recreate a similar sort of slit in an old throwaway driver and see how well it repairs.
