Allison 6 Refurb.

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Simon Hickie
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Re: Allison 6 Refurb.

Unread post by Simon Hickie » Tue Dec 12, 2017 1:51 pm

OK, will have a go. Meantime I'd better put the drill to normal DIY domestic use.
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” George Bernard Shaw.

Simon Hickie
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Re: Allison 6 Refurb.

Unread post by Simon Hickie » Sun Dec 17, 2017 3:19 pm

Green Russians now installed. I think I've fixed the recalcitrant bass driver: the connections bar had bent inwards and the tinsel wires were vibrating against the cone at larger excursions.

I'm now iterating the resistor values. 6.8 ohms seemed a touch hot & going back to 10 ohm is again showing as a little muted in the treble department. Time to try the 8.2 ohm.

I also think I know why Mrs DQ asked DQ to turn the bass down. When standing, especially when close to the speakers, you are getting much more of the upper bass / lower mid output.

With respect to the semi-omni presentation, it's different but not massively so from a well executed P&S setup. I'm thinking of my friends setup with the Lalis. With his system, soundstage is deep, wide and high with no suggestion whatsoever of sound emanating from the speakers. Hiowever, where semi-omni scores heavily is in bass performance. My go-to track is Catherine Wheel's Thunderbird. The bass can be overbearing and muddy on even a good P&S system. I put this down to the inherent problems associated with speakers that do not go against a wall: bass cancellations and reinforcements give a wildly uneven bass performance. A semi-omni like the Allison 6 which goes pretty well flat against the wall avoids all of this. On my Allisons, the above track shows no evidence of bass bloat or boom.
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” George Bernard Shaw.

Simon Hickie
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Re: Allison 6 Refurb.

Unread post by Simon Hickie » Sun Dec 17, 2017 6:43 pm

We're getting there. The 8.2 ohm resistor is there or thereabouts. The other thing is that I've gone for bare wire connectors to the Allisons (despite the &$£%ing awful period binding posts. This means that I have been able to get the speakers to within less than a centimeter from the wall. Bass is tight despite the lack of steel lining and extends pretty well if lacking a little weight. It's a bit 'boxy' though thanks to no steel and no stuffing. The bass buzz has not returned, suggesting my diagnosis and fix was correct. Rather oddly, getting the speakers right back to the wall seems to have added sparkle to the top end - or perhaps it's bare wire connectors.

So a trip to the nearest steel stockholder is on the cards for the new year to complete the job by reducing or eliminating the boxiness.
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” George Bernard Shaw.

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karatestu
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Re: Allison 6 Refurb.

Unread post by karatestu » Sun Dec 17, 2017 6:58 pm

Coming along nicely Simon.

What are the cabs made of ? Steel is probably a must if chipboard. Chipboard really is awful stuff especially the cheap crumbly stuff i used for my bass cabs. I need to get some steel on mine too just to see what happens.

I nearly bought a pair of Allison 6's when i first joined here. They were already doc modded by the owner. I chickened out in the end, cant remember why.

I am going to play about with binding posts and try them pointing down if i can design it in then cable will go straight down to the floor.
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Simon Hickie
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Re: Allison 6 Refurb.

Unread post by Simon Hickie » Sun Dec 17, 2017 7:47 pm

They are made of chipboard Stu! Currently listening to some Orbital (Halcyon +On +On from the brown album) and very engaging it is too. The cabs are definitely joining in more that I would like. I think I'm going to need those base cabs though...

I might plumb in my subwoofer from the home cinema system to see what happens. It's an MJ Acoustics one which I set to the lowest frequency and pretty low volume level. On other systems it just tends to provide some slightly firmer foundations for the main speakers.
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” George Bernard Shaw.

Simon Hickie
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Re: Allison 6 Refurb.

Unread post by Simon Hickie » Tue Dec 19, 2017 10:31 am

I think a Big Bass Cabinet is seriously on the cards for the new year. When in my usual seating area and with volume set to comfortable levels, the sound levels inflicted on other parts of the house are significantly louder than with P&S. This is due in my case to having a door on each side wall next to each speaker. The upward firing bass/mid is doing an excellent job of also pushing sound out of the room and up the adjacent stairwell unless the doors are closed, which one cannot be currently be due to house-moving stuff in the way. When that finds a home, I may be able to judge better.

My thinking about the BBC is that I will get more bass and lower mid from a 12 inch driver placed close to the floor. I might then be able to throttle back the Allisons a bit. I have 25mm ply in mind for the BBCs in a 40 to 50 litre enclosure which should put the Allisons at an appropriate height.
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” George Bernard Shaw.

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karatestu
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Re: Allison 6 Refurb.

Unread post by karatestu » Tue Dec 19, 2017 5:35 pm

Bbc is the way to go Simon. You know it makes sense ;) Not that i am trying to influence you in any way :liar:
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Simon Hickie
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Re: Allison 6 Refurb.

Unread post by Simon Hickie » Tue Dec 19, 2017 5:59 pm

Naturally I am not influenced in any way whatsoever by your efforts with your much documented speakers Stu.

As an aside (& maybe the Doc could chip in) given that it seems that only this forum seems to have somebody doing isobarics properly, in a BBC with a front firing bass driver at the base of a cabinet say 35cm wide x 35 cm deep by 70cm high, with the cab divided in two, could one have the 'internal' driver facing downwards? I think you may see where I'm going with this... ;)
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” George Bernard Shaw.

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Dr Bunsen Honeydew
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Re: Allison 6 Refurb.

Unread post by Dr Bunsen Honeydew » Tue Dec 19, 2017 6:19 pm

No I haven't got a clue where you are going, both drive units have to be in the same plane and the back driver must have no separate access to the outside of the cab apart from through the front driver. The driver can be place front and back or top and bottom as in a semi omni config. Cubix and Cubix Pro use this config.

It is not my fault other people can't go back to the guy who came up with the concept and patented it, but Linn well of course they know more than anyone else on the planet, don't they, like feck they do.

Simon Hickie
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Re: Allison 6 Refurb.

Unread post by Simon Hickie » Tue Dec 19, 2017 6:48 pm

Thanks Doc, that clears it up for me. I'm trying to avoid any other explanations based on most (not NVA) commercial designs and am attempting to track down the authentic Harry F Olson info.

I want to use the Allison Sixes as a top section and some kind of big bass cabinet as the bottom section. Option one is the 12 inch driver in a 40 to 50 litre box. Option 2 is perhaps a pair 8 inchers per side in an isobaric configuration, but avoiding something too deep. In a cabinet of the size suggested above I am supposing the divider could be vertical giving two equally sized compartments of say 60h, 30w & 15d with the drivers at the bottom of each section, but that might make the cone to magnet distance a bit tight.

Thinking some more, I think sticking with the 12 incher option makes more sense. I have the drivers and the air shifting capability will be better with more cone area.
“The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.” George Bernard Shaw.

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