Northwest Horns w/ slanted cabinets

[louped garouv]

Anyone familiar with these? Seems like there may have been a few variants on the theme produced.
these have the 3 vane horns - possibly Northwest model 340 from what I have gleaned....

thanks in advance for any insight.

[Earl K]

Yep, I'm quite familiar with those NorthWest Horns ( owning more than 2 dozen of them ).

If they are @ 24" across then they are the Model 340 ( meant for drivers with a 2" exit ) . There was also a larger model / the 350.

They are ( as is the case with virtually all conical/planar horns ) very "open" sounding. That's the good news.

The bad news is ( & also a result of the mostly planar profiles contained within the horn bell ) the horn barely loads the intended large 4" diaphragm drivers down to 800hz.
- We now know ( I suppose ? ) through the emergence of the M2 horn ( waveguide ) that horn loading isn't always the bug-a-boo previously trotted out as finger-waggling piece of dogma ( ie;" thow, shalt not break this rule /upon fear of audio death " ).

Anyways, with a bit too much drive ( and perhaps a sketchy crossover point ) the expensive destruction of one's 4001 diaphragms is a simple bump of the fader away ( just ask Maryland Sound ).

These horns found a happier niche within the recording studio market ( back in the 80's ) .

Their most significant design heritage looks obvious ( to these eyes ) as being inspired by the W.E./Altec 32a/32b ( redesigned for a bigger entrance with most of the throat removed ).

FYI, there's a ( necessary ) metal adapter plate that goes between the horn & the driver ( since all the versions that I've seen ) didn't have a flange to mount the driver onto.



:)

[louped garouv]

'Tis very much appreciated Earl --

I'm guessing that you might have posted a pic of the mounting plate --
but all I see is a small "X" box/icon -- I'll pull this up with another browser tonight...

I'll have to fabricate this I think, as they are not present in the pair I have --
I'm thinking an appropriate sized hole for the driver throat - in some thick sheet metal stock, w
ith properly places holes for driver mounting to the plate and then to the flare - would basically do the trick?


(neither are the ring radiator driver mounting holes - but easily remedied)

I'm planning on using some 2440 motors with the Truextent diaphragms with the cabinets -
so I will certainly take your warning about a proper crossover point very seriously....

Best regards,
David

[Earl K]

You're Welcome Louped !

I'll take another picture of the stock plate and post it here.

I had received a stock adapter ( way back when in 86 ).

I simply made the rest out of 1/8" hardened aluminum alloy ( I'll remeasure & get an accurate thickness ) .

I purchased mine as cut stock from a local metal fabricating company .

The most difficult aspect of making your own adapter is producing a nice clean 2" wide hole.

I punched mine out using a ( fairly pricey ) GreenLee hole punch.

As seen in the following picture ( click it, to go see it sold via Amazon.com );
https://images-na.ssl-images-amazon.com/images/I/41KMmMhZ-FL.jpg (https://www.amazon.com/Greenlee-737BB-Knockout-2-Inch-Conduit/dp/B0025PQNR2)

:)

[louped garouv]

that advice also helps much. :)
I'll have to reach out to some electricians I know,
that seems like something a commercial sparky might have around, maybe...
(I can hope at least.... )

[Tim Rinkerman]

A drill press and a 2" hole saw is just as nice,and a lot cheaper...

[Earl K]

A drill press and a 2" hole saw is just as nice,and a lot cheaper...

All good points Tim! I had forgotten that I didn't have easy access to a drill press (back then in 86), hence the punch usage .

Louped, here's the promised picture ( better late than never, I hope ).

72364

One can see the effects of not using a drill press ( ie; wandering drill bits, resulting in holes well off the penciled lines / an oversized hole means it's still "all-good" ! ).

BTW, ( somewhat incredibly ), I found one cardboard wrapper ( that encased the cut plates ) that had some relevant info.

The alloy used in my plates was Aluminum Alloy, 6061 (https://www.metalsdepot.com/products/alum2.phtml?page=sheet&LimAcc=%20&aident=)

:)

BTW, that plate is 7.75" x 8"

[grumpy]

Hole saw on a drill press? In sheet/thin metal? Personally, I'd go for the punch if possible/available.

Make for darn sure the work piece is firmly clamped to the table.
Absolutely no 'free hand' or it could be disastrous. Even clamped the saw will tend to grab,
particularly as it breaks through.

Sorry if I sound like a shop nanny. I like my fingers where they are.

[louped garouv]

this is perfect, thanks!

and thanks for the shop safety tips -- always appreciated.

[Earl K]

Hole saw on a drill press? In sheet/thin metal? Personally, I'd go for the punch if possible/available.

Make for darn sure the work piece is firmly clamped to the table.
Absolutely no 'free hand' or it could be disastrous. Even clamped the saw will tend to grab,
particularly as it breaks through.

Sorry if I sound like a shop nanny. I like my fingers where they are.


Well, we all need a "shop nanny".

I'm thinking that metal cutting fluid (https://en.wikipedia.org/wiki/Cutting_fluid) is a necessity .

I have yet to try this out ( I may using the neighbours drill press & my hole-saw & some cutting fluid/oil ) .

:)

[louped garouv]

https://www.metalsupermarkets.com/wheat-ridge/

looks like I may have an easy way to get this adapter done...
if it isn't too spendy, I may have them provide the adapters


I'll dis-mount one of the horns, and stencil out the pattern required, scan it -
then request a quote for 2 adapters

:)

[Danny B]

I'm looking for some northwest horns model 250 24" wide. Anyone have them for sale.

[Danny B]

I'm looking for some northwest horns model 340 24" wide. Anyone have them for sale.

[rl5555]

I'm looking for some northwest horns model 340 24" wide. Anyone have them for sale.

Hi Danny, I got few pairs of Northwest 340 horns for sale, I'm few miles from Downtown LA.
80061

[Earl K]

Here's a pic showing these horn in action ( within an un-named studio ).

http://techtalk.parts-express.com/filedata/fetch?photoid=1364559


:)

[rl5555]

I notice on most of the 340 horn setup that I saw from the picture the horn opening is in front of woofers by few inches.
Is it for time alignment?
Anyone know if there's exact measurement for this distance?

[Earl K]

I notice on most of the 340 horn setup that I saw from the picture the horn opening is in front of woofers by few inches.
Is it for time alignment?
Anyone know if there's exact measurement for this distance?


Only Acoustic Measurements of the pictured setup ( that capture the offsets ) would be able to answer your question ( so that leaves me unable to help ).

Sorry :)

[Danny B]

Hi Danny, I got few pairs of Northwest 340 horns for sale, I'm few miles from Downtown LA.
80061
I'm interested in your model 340 Northwest Horns Danny 310-528-8888