Allison 6 Refurb.

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Simon Hickie
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Allison 6 Refurb.

Unread post by Simon Hickie » Sat Dec 02, 2017 6:25 pm

Well, the house move has happened and the hifi room is slowly taking shape. There's lots to do so the DIY speakers will have to sit on the back burner for a bit. However, I have acquired a pair of Allison 6 speakers in need of refurbishment. The cabinets are in excellent order, but the bass drivers need attention. I have two choices: refoam the drivers, or replace them. Given that I will be DIYing some mid/top cubes with a big bass box, I'm going to run the Allisons as a temporary solution before relocating them to the TV system.

Any thoughts on refoaming vs. driver replacement?
“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 » Sat Dec 02, 2017 6:33 pm

Resale value then refoam - better music then simple Doc Mod. Tweeter is good keep it, new doped 8 inchers, remove wadding. 3.3mfd tweeter protection, nothing on bass mid adjust pad for tweeter by ear. If you want more the line the cab with metal of some sort.

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karatestu
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Re: Allison 6 Refurb.

Unread post by karatestu » Sat Dec 02, 2017 8:47 pm

Get some steel lining in there Simon, you know you want to :guiness;

If you are keeping them long term then do what the doc says, you know he is right :P
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Simon Hickie
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Re: Allison 6 Refurb.

Unread post by Simon Hickie » Sat Dec 02, 2017 9:58 pm

I'm in for the long haul on these, so I think I'll do what the doctor ordered. I just have to find my doc modded 8 inch drivers... Why do removers never seem to put things in the correct room? Somewhere there's a box with my Tang Band full range drivers, SEAS tweeters & the 8 inchers, but they've not turned up yet after 12 days of unpacking.

Incidentally, the 8 inch drivers in the Allisons were horrendously dusty. It may be to to the perforated driver cover allowing loads of dust and stuff through. Suitably doc modded, they could well then form the upper section for the big bass box.
“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 » Sat Dec 02, 2017 11:17 pm

Simon Hickie wrote:
Sat Dec 02, 2017 9:58 pm
I'm in for the long haul on these, so I think I'll do what the doctor ordered. I just have to find my doc modded 8 inch drivers... Why do removers never seem to put things in the correct room? Somewhere there's a box with my Tang Band full range drivers, SEAS tweeters & the 8 inchers, but they've not turned up yet after 12 days of unpacking.

Incidentally, the 8 inch drivers in the Allisons were horrendously dusty. It may be to to the perforated driver cover allowing loads of dust and stuff through. Suitably doc modded, they could well then form the upper section for the big bass box.
Yes always listen to the good doctor. The doc does bake exceedingly good doped drivers and he has obviously found drivers with the correct parameters for doping

I should think a good blow out of the spider and shoving the end of a vacum hose up any vents to the voice coil should sort it out. I use a battery powered leaf blower to give everything a good blowing off when circumstances allow. Nothing worse than a stray bit of coper wire shorting two component legs together and then the tell tale smell of destructing integrated chip.

One problem i found with having driver magnets knOcking about in workshops is that they seem to attract every little bit of ferrous metal that you could imagine existed and then some. Good old vacum cleaner is the only thing that will sort that out. Do you give your vacum a name like i do ?
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Simon Hickie
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Re: Allison 6 Refurb.

Unread post by Simon Hickie » Sat Dec 09, 2017 11:44 pm

Phase 1 complete. The poor things were stuffed to the gunwales with cut up fibreglass so that's come out. 8 inch doc modded drivers installed and 3.3uF and 10 ohm resistor on the tweeter for starters. The top end is a bit muffled with this amount of padding, so using the 'binary chop' approach, I'll reduce it to either 4.7 or 5.6 ohms as the next step. which will add about 3db or so to the tweeter output. I'll then titrate up or down depending on the result.
“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 » Sat Dec 09, 2017 11:50 pm

I would not associate muffled with the wrong cap size, or do you mean too low a level ? Muffled to me means bad tweeter. Let us know what happens when you tweak it. Not that i am an expert though.
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Simon Hickie
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Re: Allison 6 Refurb.

Unread post by Simon Hickie » Sun Dec 10, 2017 12:14 am

Wrong resistor size. The original efficiency of the Six was about 86db. The modded bass/mid driver is 84ish. The tweeter is supposed to be a good one, but I have my SEAS unit to fall back on if needed. Not so much muffled as rather dominant midrange. Mind you, I was testing them with just an old DVD player as my daughter has borrowed the music laptop.
“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 10, 2017 8:58 am

Ah, dominant mid range. I know what that sounds like. I think i had too much whiskey last night as i did not read your post properly. Apologies.
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Simon Hickie
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Re: Allison 6 Refurb.

Unread post by Simon Hickie » Sun Dec 10, 2017 10:16 am

Ah whisky! More of a brandy person myself. Mind you, any alcohol tends to mess with my medication so I'm largely on the wagon. Back to the speakers: I think steel lining is the next & obvious step once the tweeter has been padded to taste. 5mm this time I think.
“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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