Goodmans Triaxioms

[istari_knight]

I bought what is apparently a NOS pair of "212c" Triaxioms last night. Anyone familiar with them ? I've enjoyed some axiom 301's in the past so when I saw these going cheap it was difficult to resist...



Should be good for a laugh on the end of my little EL84 amp anyway

[Reffc]

Really good vintage speakers there James, a cracking find. 3 speakers in 1 with a claimed frequency response of 20Hz to 20KHz when mounted in bass reflex cabinets of the appropriate size. (the driver has a self resonance of 35Hz)

The only thing you need to watch is amplification. They are nominally 15 Ohm speakers of high sensitivity and lowish power handling (30W from memory) so possibly best with an appropriate valve amp?

Have you got the crossovers too? Difficult to find the circuit for these now.

They need large cabinets, Circa 4.5 cubic feet or 127 litres net. Something around the 1m tall by 420mm wide by 350 would do the trick (external dims).

[walpurgis]

Wow! You'll enjoy those James. Amazing condition and very collectable. Need a big box though.

[istari_knight]

Thats exactly what I wanted to hear chaps ! I'd never seen a pair before but the second I clapped eyes on them I knew they weren't the usual dross

Paul, I'm playing with a little 12wpc EL84 amp at the moment so no worries on that front. Whilst searching for information I stumbled across a few pictures which revealed the crossover is contained within those cylinders on the fly leads, each contains a waxy looking inductor, a film cap and what appears to be a rheostat pot.

Big cabinets will be alright, my work in progress listening room is a decent size & will be for my entertainment only [converted 18x12 summerhouse] I probably won't be doing anything with them until thats completed but what sort of cabinets do we think might work best ? There's such little info out there... Would a large cab designed for 12" DC's work ?

[Reffc]

Thats exactly what I wanted to hear chaps ! I'd never seen a pair before but the second I clapped eyes on them I knew they weren't the usual dross

Paul, I'm playing with a little 12wpc EL84 amp at the moment so no worries on that front. Whilst searching for information I stumbled across a few pictures which revealed the crossover is contained within those cylinders on the fly leads, each contains a waxy looking inductor, a film cap and what appears to be a rheostat pot.

Big cabinets will be alright, my work in progress listening room is a decent size & will be for my entertainment only [converted 18x12 summerhouse] I probably won't be doing anything with them until thats completed but what sort of cabinets do we think might work best ? There's such little info out there... Would a large cab designed for 12" DC's work ?

I think that they would be best with vented or ported cabinets James. You can work out the rough port dimensions running a sim on the recommended box size and tuning the port appropriately. To get the correct tuning a few things are usually needed such as the Qts of your speaker bass driver and its Vas. However, these were made before the Thiele-Small parameters came into being so you may need to play a little with tuning. I'd start by using a couple of 100mm cardboard tubes at around 150 to 200mm long and try different lengths until you get the best response. You can calculate it more accurately by building a small sealed test enclosure (say 30 litres) which is used to them work out Vas and Qts for a better approximation of the port. You could also run with a variable slot (vented) arrangement and play around with that. Otherwise it's a case of doing some in depth research on these.

[Reffc]

OK...a little research has thrown up that the 212c drivers had a "Q" of closer to 0.7, so they'll work well in bass reflex, sealed or even open baffle configurations. I've found these cabs for the Goodmans 12 inch drivers so perhaps somewhere to start?

[Ali Tait]

I have a set of Axiom 401, must give them a go sometime, they've been stored away for years.

[Macca]

'For amplifiers up to 15 watts (30 watts in U.S.A)'

What's that all about? 1 Brtish watt = 0.5 American watts? I've never heard that before.

[istari_knight]

I think that they would be best with vented or ported cabinets James. You can work out the rough port dimensions running a sim on the recommended box size and tuning the port appropriately. To get the correct tuning a few things are usually needed such as the Qts of your speaker bass driver and its Vas. However, these were made before the Thiele-Small parameters came into being so you may need to play a little with tuning. I'd start by using a couple of 100mm cardboard tubes at around 150 to 200mm long and try different lengths until you get the best response. You can calculate it more accurately by building a small sealed test enclosure (say 30 litres) which is used to them work out Vas and Qts for a better approximation of the port. You could also run with a variable slot (vented) arrangement and play around with that. Otherwise it's a case of doing some in depth research on these.

Thanks for the info Paul, I used my old 201's on an open baffle like this: http://jelabsarch.blogspot.co.uk/201...en-baffle.html

Sounded great but were A) fugly, and B) difficult to position so I'm not in a hurry to replicate that... A proper cabinet is definitely the way forward. Looks like It'll take some trial & error.

[istari_knight]

'For amplifiers up to 15 watts (30 watts in U.S.A)'

What's that all about? 1 Brtish watt = 0.5 American watts? I've never heard that before.

It is odd but Goodmans printed the same on every driver

An American forum member said the following on the subject: "The difference in rating is simply that of the difference between RMS rating and IHF rating. The Institute of High Fidelity (an American organization) measured power from positive peak to negative peak, which increases the apparent power."

Seems legit ?