Old fashioned 12inch 3 way

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Dr Bunsen Honeydew
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#16 Re: Old fashioned 12inch 3 way

Post by Dr Bunsen Honeydew »

ed wrote: Mon Jun 12, 2017 6:45 pm what about aerolam like was used in the celestion sl600.
Would this have similar properties to steel.
Is it still available?
is it workable?
I am sorry but in my opinion it defeats the object, I want mass, I want heavy, I want solid. That was the whole point of steel plate lining in Doc Mods.
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Dr Bunsen Honeydew
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#17 Re: Old fashioned 12inch 3 way

Post by Dr Bunsen Honeydew »

Thinking of permanently fitted large (four to six inch) industrial casters as stands.
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Dave the bass
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#18 Re: Old fashioned 12inch 3 way

Post by Dave the bass »

Being an eminent speaker-thinker-upper myself....Whaddaabout.... Sand.

Build a speaker, or even cheaper, just take an old clunker from a skip that we can do the doping mods to and remove the crossover and put in just cap n resistor.... but then build another 'cabinet' around that, a bit like double glazing but in wood. The gap, say about 2 inches or so, fill it with sand. Same principle as Wharfdale SFB speakers but the entire cabinet, not just a baffle?

Poss Nobel Prize award next year for me or public humiliation? (and a lot of sawdust and sand down the shed, and the living room, and the garden, and the wheelie bin).
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Dr Bunsen Honeydew
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#19 Re: Old fashioned 12inch 3 way

Post by Dr Bunsen Honeydew »

Not for me.

Lots of different ways to do things.
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Ray P
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#20 Re: Old fashioned 12inch 3 way

Post by Ray P »

Dr Bunsen Honeydew wrote: Mon Jun 12, 2017 7:04 pm ...I want mass, I want heavy, I want solid.
Concrete (or plaster)?
Sorry, I couldn't resist!
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#21 Re: Old fashioned 12inch 3 way

Post by Dr Bunsen Honeydew »

My first speaker project of any consequence was a Wharfedale 12 inch 3 way kit. Chipboard lined with concrete keyed with nails. About 1970. I even have a pic somewhere of me brocade flares long hair and all, sitting cross legged pouring in the concrete sitting in the garden.

Seriously folks nothing anyone says about cabinets will have any effect on me, I have tried most things in my time, and I know what I want. BUT please try it yourself.

Nothing beats 20mm acrylic, its balance of qualities is perfect for me, but done that wrote the book on it. Projects are for FUN!! :bounce:
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shane
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#22 Re: Old fashioned 12inch 3 way

Post by shane »

I'm intrigued by this. For many years I had Heybrook HB3s which I think are along similar lines, i.e. 3-way, 10" bass unit, relatively simple crossover and big IB cabinet, albeit with conventional chipboard construction. Having spent a couple of years assembling the beasts, one of the biggest problems was sealing the midrange enclosure so the mid driver didn't get pushed about by the bass unit. That's going to call for some complicated welding, I'd have thought?
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#23 Re: Old fashioned 12inch 3 way

Post by Dr Bunsen Honeydew »

Sorry lack of understanding. Ed Villchur understood it (well he invented it) and many others in the USA did, we seemed to have picked up some bullshit somewhere along the line. You have to understand the difference between a sound pressure wave and an air pressure wave that happens to contain a signal path. Acoustic suspension is an airtight cabinet, the driver *sits* on the air of the enclosure, it stops extension unless it is dictated by the signal.

http://www.aes.org/aeshc/docs/recording ... lchur.html
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#24 Re: Old fashioned 12inch 3 way

Post by shane »

Exactly. The bass unit requires an airtight cabinet, so how do you mount the midrange unit on the front baffle without compromising the airtight box? HB3s had a 4" plastic tube from front to back that was sealed from the main enclosure and gave the mid its own mini IB, but you usually do things differently....
The world looks so different after learning science. For example, trees are made of air, primarily. When they are burned, they go back to air, and in their flaming heat is released the flaming heat of the Sun which was bound in to convert air into tree.
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#25 Re: Old fashioned 12inch 3 way

Post by Dr Bunsen Honeydew »

You still don't see my point, you are still working on a false presumption that the midrange driver needs its own enclosure, in a properly designed acoustic suspension it doesn't.

You need to let go of pre conceived ideas someone else has foisted on you. You wasted your time doing what you tried to do.

Just watch the project develop, you will see.
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#26 Re: Old fashioned 12inch 3 way

Post by Dr Bunsen Honeydew »

Both bass and so called midrange drivers are used full range and are just in parallel with no electronic components. The drive units are differentiated by cone doping. As far as the air pressure in the cabinet it will just see them both as part of the same system as a combination of the cone area. Same as if it was two parallel bass drivers.
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#27 Re: Old fashioned 12inch 3 way

Post by Dr Bunsen Honeydew »

As an aside I found this on the Acoustic Suspension AES paper. See where we went wrong, we forgot about the room!!!!

All down to BBC bullshit, their way top corner picture.

Image
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shane
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#28 Re: Old fashioned 12inch 3 way

Post by shane »

So the pressure generated by the bass unit in the cabinet is countered by the same signal controlling the movement of the midrange?
The world looks so different after learning science. For example, trees are made of air, primarily. When they are burned, they go back to air, and in their flaming heat is released the flaming heat of the Sun which was bound in to convert air into tree.
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#29 Re: Old fashioned 12inch 3 way

Post by ed »

oooh, I'm still trying to get my head around this, it looks like a trixy concept

If I'm reading your synopsis correctly then the 12" driver must have exactly the same compliance as the smaller driver, otherwise in my head I can see them interfering with each other. Mainly the 12" interfering with the smaller one.

If this is the case then it looks necessary to have the Qt figure for both drivers, but again in my naive head I didn't think this figure was available to Ed Vilchur when he was doing his work. I didn't think it was an exact science until Thiele and Small did their thing. Does this mean that Ed was doing all this by trial and error?

further, to approximate the volume for the enclosure in todays terms how would you sum the Qt of the 2 drivers with respect to the total compliance?

apologies if this is venturing into the objective realms Richard.

edit: just had a further thought...this could reap big benefits if the 12" was a field coil driver, then you could twiddle to get a good match. This would of course necessitate the use of measurements as ones ears would not produce a good result for somebody elses ears, i.e level the playing field(no pun)
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shane
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#30 Re: Old fashioned 12inch 3 way

Post by shane »

If I put Also Spracht Zarathustra on at a decent level, why won't the bass unit blow the midrange cone out of it's basket? An extreme case, I grant you, but I'm just trying to get my head around the concept.
The world looks so different after learning science. For example, trees are made of air, primarily. When they are burned, they go back to air, and in their flaming heat is released the flaming heat of the Sun which was bound in to convert air into tree.
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