Hi, you've probably opened the amp by now, but there's not much room in there for a larger (width or depth) driver. The baffle is cut funny and it has extra material around the 8", which prevents a larger diameter speaker without a new baffle or extensive reworking. There's about 3.75" of clearance between the baffle and the chassis, which makes most 10" speakers (and most AlNiCo guitar speakers of any diameter) a no-go.
I did find the Celestion to be unpleasantly bright in the upper midrange, even after breaking it in. I swapped it for a Warehouse G8C, which was much, much better. Weber also makes a British style 8" ceramic that I think would fit, but it's around $80-90.
The Origin 5 is a cool amp, but I ended up selling it after I acquired an Origin 20 and several other amps. Can't keep them all!
I manufacture speakers from scratch so very well know kind of steel used, since I regularly buy a few hundred kilograms of it at a time.
Best is lowest carbon possible but is very hard to find, so usually it´s SAE1008/1010 cold rolled steel plate.
Polepieces "should" be the same, but lathe guys HATE it because being very soft and malleable (for steel that is) it produces looooonnnnngggg sharf which tends to get stuck everywhere, even catch and break cutting tool tip, go figure, so typical is 12L14 which contains tiny Lead droplets in the alloy which make for self-breaking easy to hndle scales.
Lead also "lubricates" cutting tip so they love it.
Not as good magnetically but hey, machining advantages far compensate for the tiny loss.
The coercivity and the shape of the hysteresis loop are certainly different, but the belief that Alnico de-magnetizes and re-magnetizes itself as music is being pumped through the speaker (compressing the signal in the process) is almost certainly complete nonsense. Without any solid evidence (or a even a convincing mathematical model) for the hypothesis, it is about as believable as the Loch Ness Monster.
It IS nonsense, only imagined by people who don´t know even a little bit of Magnetics and Hysteresis curves.
In fact the "convincing Mathematicalmodel" says it is nonsense
You CAN move a magnetic working point up and down the original one, but EVERY TIME YOU WILL RETURN TO A LOWER ONE
, it´s a lossy process and that´s exactly how DE-magnetizers work You apply AC to a "magnetizing" coil and lower its value to zero= fully demagnetized magnet.
Some (not all) Magnetizers incorporate a de-magnetizing mode, they simply connect the capacitor bank to the coil, and let it oscillate back and forth, the coil DC resistance continuously dissipating energy and damping oscillation down to zero in a fraction of a second.
Seems Magic being able to pull magnet away effortlessly, with your own hands.
Mind you, it´s possible only in very high voltage *film* capacitor power banks , so the most expensive ones; on typical electrolytic capacitor ones back voltage will make them explode like a small Nuke, no kidding.
We are talking thousands of Joules stored energy, capacitor banks are fridge sized.
As of:
Absolutely NOT.
The voice coil generated magnetic field is perpendicular, 90 degrees away from the gap field, so it does not do one iota to it.
For 2 very good reasons:
1) that´s how an electric motor works!, current in the wire perpendicular to magnetic field.
2) IF it shifted main magnet field up/down it would quickly demagnetize it.
About AlNiCo vs. ferrite: Up to the end of the 1970ies all big manufacturers used AlNiCo magnets in their high end drivers, due to their superior magnetic strength/mass ratio. In 1977 a civil war broke out in Zaire, hence the major source for the worldwide cobalt supply ran dry due to an international embargo. Consequently all major manufactures (JBL, EV, Altec, Tannoy etc.) switched to ferrite drivers. And the myths began ...
Regarding the magnetic flux in the gap, the magnet material doesn't play any roll at all. For instance, in 1978 JBL replaced the former AlNiCo magnet in their 2205H's for ferrite without altering this driver's TSP's!
Yes, for whatever reason AlNiCo magnets are prone to lose their energy in drivers that are pushed hard for a long time, e.g. musical instrument or PA speakers. This can be measured with a Gauss meter. And they also lose some of their magnetism if the magnetic circuit is opened. These magnets need to and can be re-magnetized, but don't ask me how this is done without disassembling the whole magnet structure.
Nowadays we have neodymium magnets for high-end drivers which excel all other known materials in terms of energy/mass ratio. Consequently neodymium drivers are much lighter than comparable ones even with AlNiCo magnets. The heaviest ones are the ferrites: Comparing the JBL K140 with the E140 means 12.5 kg vs 14.5 kg!
And again: If you'd build a pair of drivers that only differ in their magnet materials, say ferrite vs. neodymium, but not in the magnetic field, i.e. have the same BL value, you'll get two drivers that perform identically.
Best regards!
...Regarding the magnetic flux in the gap, the magnet material doesn't play any roll at all. For instance, in 1978 JBL replaced the former AlNiCo magnet in their 2205H's for ferrite without altering this driver's TSP's!
Yes, for whatever reason AlNiCo magnets are prone to lose their energy in drivers that are pushed hard for a long time, e.g. musical instrument or PA speakers. This can be measured with a Gauss meter. And they also lose some of their magnetism if the magnetic circuit is opened. These magnets need to and can be re-magnetized, but don't ask me how this is done without disassembling the whole magnet structure.
Nowadays we have neodymium magnets for high-end drivers which excel all other known materials in terms of energy/mass ratio. Consequently neodymium drivers are much lighter than comparable ones even with AlNiCo magnets. The heaviest ones are the ferrites: Comparing the JBL K140 with the E140 means 12.5 kg vs 14.5 kg!
And again: If you'd build a pair of drivers that only differ in their magnet materials, say ferrite vs. neodymium, but not in the magnetic field, i.e. have the same BL value, you'll get two drivers that perform identically.
Best regards!
True.
Voice coil has NO CLUE on magnetic material or magnet geometry, it can even be an electromagnet, all it "knows" is magnetic flux in the gap.
Broadly, Ferrite Alnico curves are "soft", and moving up-down is lossy, IF you vary magnetic flux it always returns to a lower point each time.
Demagnetizers work that way.
Opening-closing a magnetic circuit, even magnet shifting (bumps or had knocks) causes magnetic field variations, again weakening it each time.
They are not disassembled but magnetized inside the fully assembled magnetic systems.
In fact, many factories (such as RCF) magnetize speakers already inside the shipping carton!!!!!
My large magnetizer has a 15 cm gap, I also magnetize my 12" speakers inside the cardboafrd shipping box.
!5" and 18" ones are taller, frame must rotate something to let the top polepiece in.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.