Goodmans maxim, BBC found alternative replacement, what is it....

[hbc]

Goodmans maxim woofer, BBC found alternative replacement, what is it....

This pair of ex BBC maxims were for sale on eBay recently. I noticed that one of the woofers had been replaced. The BBC, must have confirmed by measurements it's suitability as a replacement, it must be quite a similar driver.

So does anyone know what it is. I have some Double maxims I am rebuilding and on the look out for (obtanium) woofers........

or any other similar ones that may work for that matter?

thanks

 

[Colin]

It's likely to have been another Goodmans driver from the period. There were a couple of variations made. You may have to remove it from the baffle to see if there is any label on the back.

 

[hbc]

Hi, I don't recognise it as a Goodmans, not that I know everything. I think the original maxim woofer is a development of the old midrange used in the magnum for example, at least I am pretty sure it uses the same cone, "just" with a long travel magnet and suspension coil. I think the dimension 8 mid range is another variant. the Goodmans has a flared cone, where as this one is straight sided. Looks more like a Philips or Celestion to me.

 

[irext]

The one on the RHS has a Bextrene cone (KEF, Celestion etc). The one on the left looks like a paper cone. Quite different characteristics.

 

[hbc]

To me the one on the right looks like a doped paper cone. Its that big roll surround that I like most though.....

 

[hbc]

mystery solved... it is a later version. More unobtainium.
I am going to graft some dimension 8 woofers in to my very tatty double maxim boxes, they are a little bigger with a steel basket and probably the wrong impedance, but seem a close family member.

 

[system7]

The BBC report on the Goodmans Maxim is still available:
http://downloads.bbc.co.uk/rd/pubs/reports/1965-09.pdf

2kHz 2nd order crossover to cone tweeter. 4.5" paper bass with rubber roll surround, we'd guess. 5L closed box.

Wonder if these Peerless 830870 polycones would fit? They look suitable for closed box. You might investigate the crossover, and whether the basses are series or parallel wired, which affects impedance greatly.
https://www.falconacoustics.co.uk/drive-units-1/peerless-830870-midwoofer-hds-range.html

The tweeter in yours looks like that ancient Philips AD0160 mylar unit that Troels Gravesen evaluated, so the crossover must be nearer 3kHz: http://www.troelsgravesen.dk/WWDT.htm

The more modern take on this sort of thing, which might be more satisfying is this: http://www.troelsgravesen.dk/VifaPL14WJ-R2604.htm

 

[hbc]

Aha, I have some on my bench. I decided to build some almost maxims, using some dimension 8 woofers, thinking that they would be similar.... Low and behold I now have a pair of the newer ones (issue iii?).
My family of genetic relatives:


I can now find out how similar or not the 8s are to the maxims.....