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Goodmans rebuild

interalian

interalian

Super Member
I have a pair of 16 ohm Goodmans Axiom 112 drivers (10" fullrange 40-15kcps, max 12W) that were purchased in ~1960 by my dad on his first foray into stereo, paired with an Eico HF-81 he built from a kit. These drivers are in fine condition so I'm thinking about getting them ready for when I resurrect the aforementioned Eico.

The cabinets may have been built locally as they contained a Pioneer horn tweeter (vertically oriented) as well as the Goodmans driver. I'm not sure about the type, but the cabs are 23.5"h x 19"w x 10.5"d (inside) made from 3/4" particle board. The 10" driver was* mounted, centered near the top of the cab and the port was a 7x7x3.5" snorkel with the open end facing up toward the driver. The snorkel was about 1.5" off the bottom of the cabinet and spoke through a 7x3.5" port (landscape orientation). There was 1" thick rag insulation on the back panel and on the top and one side (classic hard/soft alternation).

Any thoughts about the type of enclosure this is (was)? I remember them sounding very nice back in the day but were easily overdriven even with the 14w Eico, especially with +15db bass boost at 50cps on that amp.

Is there any particular 'magic' about this cabinet type or could it be built with the driver mounted on a side instead of the face?

p1010003.jpg


*(I say was, 'cuz I hacked them up 25 years ago and converted them to a 3-way with 12" woofer. They sounded awful...)
 
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Woofer's gotta be on the front if it's playing anything above 200 Hz, as that is directional. Let's see the baffle without the grille. Is the baffle removable?

15 kHz is doubtless fantasy in contemporary terms. I do know what I'd be building with them; we provide components for 16-Ohm woofers over there, too.... :thmbsp:
 
Zilch said:
Woofer's gotta be on the front if it's playing anything above 200 Hz, as that is directional. Let's see the baffle without the grille. Is the baffle removable?

15 kHz is doubtless fantasy in contemporary terms. I do know what I'd be building with them; we provide components for 16-Ohm woofers over there, too.... :thmbsp:
Click to expand...

Baffle is not removable. Here's a shot with 'skirt up'. I fitted Philips dome mid and tweeter (dig the recessed mounting...) plus 12" woof. The cabinets truly are not suited for those drivers - way to flexy.

p1010001-1.jpg


By side mounting, I meant the revised cabs would be rotated so the 'depth' would become the 'width', 10" driver mounted on the short side, up top. These cabinets are rather ungainly in their original configuration. I guess my real question is what was the original port design called and would they work the same if the baffle, driver and ports were moved to the side?

p1010002-1.jpg


I suspect you're driving (pun intended) at e-wave, yes? These drivers would certainly be capable of hitting 1.6kHz - they were originally crossed at 3500Hz IIRC for the horn tweets (you can see the openings on the baffle).

Here's a sketch of the original setup.

p1010002-2.jpg
 
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They're going to be ungainly deep and asymmetrical if you mount woofers on the side, and it doesn't look like those Goodmans will fit there.

Are those nails on the edges of the front baffle, it being glued on? A cat's paw and your router would make short work of removing that, to be replaced with a new one of birch ply mounting the Goodmans and a waveguide, or whatever. Is dad still around to appreciate this effort?

The original was a ducted rectangular port, perhaps, of indeterminate tuning. I doubt you're going to get big extended bass out of those woofers, but I have been wrong before. You can measure their T/S parameters using Woofer Tester, and the box tuning, as well, a worthwhile investment for less than $100, I believe they are.... :yes:
 
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Zilch said:
They're going to be ungainly deep and asymmetrical if you mount woofers on the side, and it doesn't look like those Goodmans will fit there.

Are those nails on the edges of the front baffle, it being glued on? A cat's paw and your router would make short work of removing that, to be replaced with a new one of birch ply mounting the Goodmans and a waveguide, or whatever. Is dad still around to appreciate this effort?

The original was a ducted rectangular port, perhaps, of indeterminate tuning. I doubt you're going to get big extended bass out of those woofers, but I have been wrong before. You can measure their T/S parameters using Woofer Tester, and the box tuning, as well, a worthwhile investment for less than $100, I believe they are.... :yes:
Click to expand...

Hmmm, I was going to just build new boxes but maybe just replacing the baffle would work. Downside is the top has to come off for access. I think before I get too far into it I'll try patching up those holes and re-construct the ducted port then test as 'full range'.

Dad's still around (71) and he might appreciate the re-build - that's one of the reasons to do it, plus re-building the HF-81.

Too bad Woofertester doesn't work with Mac OS...
 
The original porting on a lot of the Goodmans designed cabinets was known as an ARU (acoustical resistance unit). There were a couple of different sizes depending on the internal volume of the speaker cabinets. It is there to damp the resonance frequency of the low frequency driver the same way as the Dynaco A 25 and Dynaudio Variovent do. Should find some information if you google Goodmans or ARU.

spkrparts.
 

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The enclosures were probably built to one of the published Goodmans plans. The port you described was fairly typical. I could probably find a pdf of a brochure with some of the plans in it if you are interested.
I have an empty set of speaker enclosures for those very drivers tucked away in my garage, they're made of solid mahogany and just look too good to throw away.
 
spkrparts said:
The original porting on a lot of the Goodmans designed cabinets was known as an ARU (acoustical resistance unit). There were a couple of different sizes depending on the internal volume of the speaker cabinets. It is there to damp the resonance frequency of the low frequency driver the same way as the Dynaco A 25 and Dynaudio Variovent do. Should find some information if you google Goodmans or ARU.

spkrparts.
Click to expand...

That makes a lot of sense, thanks. I do remember this combination had great bass (used to get the grille cloth flapping) but somewhat horn-y (ugh) highs. The old Pioneer hornz were less than smooth.
 
ArtD said:
The enclosures were probably built to one of the published Goodmans plans. The port you described was fairly typical. I could probably find a pdf of a brochure with some of the plans in it if you are interested.
I have an empty set of speaker enclosures for those very drivers tucked away in my garage, they're made of solid mahogany and just look too good to throw away.
Click to expand...

Too bad you're half a world away or...
 
If you could find some Trebax horns with the 5000 cycle crossovers and resistive attenuators you might have a great sounding resto project there. PM me if you are interested in any other info on the Goodmans speakers and cabinets. I'm only a couple of hrs from where you are located.

spkrparts.
 
Thought I'd jump in here and ask a question.... I have 2 sets of Goodmans speakers. They are both triaxials and have been rebadged as Lafayette. I believe they are 15 inch and the cabinets and drivers are in very nice shape. A couple of years ago I pulled the back of one and and took a quick peak and to my surprise there was no crossovers just an L-pad . Are the crossovers hidden under the back of the driver? if so how do you get eh back off the driver? Being that these drivers are in really nice shape I want to be careful, but I'd think after 30 +- years the crossovers would be tired. thanks, Ed
 
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