Hello!

I've been investigating this bass cabinet called House of Joy. Initially designed for 15" drivers by Sir Coxson, they were used in early sound system rigs, for playing old school reggae (ska, rocksteady, lovers rock, rockers, roots). Now I have been searching a long time for pertinent info on these cabs and have found nothing. Besides a few pictures. No plans, no specs, no feedback/experience on performance.

question 1 : Does anyone have any info to share? e.g. PLANS + Specs + experience

question 2 : would it be adaptable / scalable to 18" Drivers?

those that have / had this cab are Sir Coxson, possibly Shaka, Count fire, King addies, Sir Charlies, and CountryAct. Crazy that I can't find anything on any forum...

below, the link to a few pics

https://enkismusicrecords.com/biography-clement-sir-coxsone-dodd-founder-of-studio-one/

https://www.billboard.com/music/music-news/king-addies-celebrates-35-years-with-35-gun-salute-mixtape-feat-fugees-anita-8479592/

Thanks in advance for your responses!

Best,

Tristan

Here ya go, lovely looking rig but my back has started to spasm at the very thought of moving it

Thanks for your responses guys! 

So I've done some extra searching, and found that the sub in the picture / link was not really called House of Joy. Turns out these subs I mentioned (king tubby's, sir Coxson's) were modeled after the Jensen Imperial. The apparent difference is that they seem to be a bit narrower until the last fold before the final horn expansion. Maybe better for the response below 50Hz? There's a thread on this forum from 2011, but all links are cooked. Thanks for the mention of Paul Axis, he has a beautiful rig, But those quad subs are more like the classic reflex boxes from the 60s. I've exchanged a bit with Paul, I purchased some equipment from valvatron last year, but thanks for the pointer, he's a vintage reggae sound expert, I'll send him a msg. Otherwise, what do think of the potential sound performance for this jensen-type box, if scaled for an 18" driver (PD1850) ? 

here a link to what the box looks like: https://ch.pinterest.com/pin/282530576619969871/

Cheers, and thanks again for taking the time :)

I have one which I built from the older plans, the one with the box behind the driver and the throat either side. (tried to post pictures with no luck)

I think squeezing an 18" into the simplified version, where the throat starts above the driver, would probably be easier.

It sounds great to my ears. Non optimum driver but slightly narrowed throat and loads of extra bracing. Two filters to flatten the response and I love it. 

I don't know how it would react with more than a couple of hundred watts stuck up it. Mine has a lot of extra bracing but there are some big panels in this box.

Mine was built as a vanity project during the end of covid and now lives seasonally at a beach bar where it plays rocksteady to a handful of folks once or twice a week. It moves 3m on wheels on a tiled floor.

It's super heavy, on wheels, sounds lush at medium(?) volume but I don't know about using this box design for PA applications, did I say it's heavy?

You should find more info about Jensen Imperial and it's different iterations at the more HiFi orientated DIY sites on the net. People have made mods. Double driver, bigger driver, half width cabinet etc.

Personally wondering why anyone would want to build these back breakers in this day and age, considering what can be achieved, bang per puck, with smaller 1x21" cabs, with neo drivers, and the "right amplifiers".

It would sound lovely with the drivers intended for it, would have been made for efficiency, but sticking a modern driver in it even with mods would be a waste of both cab and driver.

But for many, Reggae sound systems are a business first, hobby 2nd.

I learned from Indian DJs, the importance of the soundsystem being optimised to return every dollar possible.

Know an excellent Indian builder who used to be here, would take out 2x subs, 2x tops on sticks, 2x 40" TV screens  on stands, and 2x flaming cloth thingies, and he'd be getting paid £1K for that Indian wedding gig.

All of that lot fit in Transit SWB, doddle to move with ramp, permitted in any posh hotel or corp venue.

That Jensen lives in India. 

I get that people on this site are primarily out to make money with the best equipment to meet their requirements. That is why I suggested that the op search the more HiFi diy sites for feedback on this design. Anybody who has actually heard one will know that there is no point in trying to compare it to any kind of commercial or contemporary scoop based rig set up.

Subs and tops on sticks are there. It fits in a small car and makes people happy also, it sounds like a good set of subs with tops on sticks and weighs a fraction of the weight.

There are also a few big rigs here, though not used for weddings as far as I'm aware.

The reggae scene in India is a new thing but growing fast. There is a Sunsplash once a year with international artists in attendance. Not my cup of tea but it's very successful.

And there is a local bar in a small bay on the west coast that serves cold beer and plays old tunes to a handful of people over a totally impractical speakerbox from yesteryear that simply sounds rather nice. If the op was thinking to do something similar I would suggest that they at least consider building a Jensen Imperial and buy some small but heavy duty wheels to bolt on the bottom.

Thanks for the responses guys!

As far as my objectives, well, it's a passion. I have a job I love on the side, which finances sound system construction, and vinyl collection. So no, I am not looking at maximizing return, or anything like that. I'm just looking to make authentic old school boxes, for 60s/70s ska, roots, rocksteady & lover's rock, and still have them sound as good as possible with what we know today. Lets the analog amps be heavy, let the old boxes be heavy, I don't mind suffering a bit, it'll keep me in shape. But back to the topic at hand:

@eyeT

"I think squeezing an 18" into the simplified version, where the throat starts above the driver, would probably be easier." is there enough space to squeeze an 18" in a half (single driver)-Jensen? If it doesn't quite fit, is it possible to widen the horn path by a few mm without altering the sound too much? else what about scaling the box to 18" was wondering if that might make more sense (aside from it being heavier ).

You also said "slightly narrowed throat" do you mean the last part before the final horn expansion? by how much, do I just eyeball it to make it look like Tubby's or is there a formula of some kind I can play around with?

Cool to know about India ! In japan and the UK they've made a few as well which seem to deliver :)

Thanks again for your time.

bless up---

There are people on here with a whole wealth of knowledge. I am not one of them and never will be so I don't really feel too comfortable giving much advice on modding this box. Having said that....

During covid I had a few sheets of ply spare in the workshop so

I built the standard box using the plan on the first page of this thread.

https://forum.speakerplans.com/jensen-imperial-plans_topic50914.html" rel="nofollow - https://forum.speakerplans.com/jensen-imperial-plans_topic50914.html

I made a second baffle for a 12" but it's too small to fit an 18" driver as is.

This design may be easier to mod to fit an 18" driver. Increase the size of the removable baffle somehow perhaps?

http://www.dcaudiodiy.com/jensen_imperial/page_11.jpg" rel="nofollow - http://www.dcaudiodiy.com/jensen_imperial/page_11.jpg

By "throat" I mean the very start of the horn path behind the driver. I made the opening a bit more narrow using a simple equation I found on this site. That smoothed out the response from the 'not ideal' driver at the expense of a little low extension. 

That reversible throat mod and extra bracing is all I changed.

That's my tuppence worth but I think you would do well to read some of the threads on Diy Audio. There is a fair bit of discussion about modding this box on there.

I must emphasize how flopping heavy this box is. It's not practical, there is lots of dead space and you must add more bracing. Not keep fit heavy, visit to the doctor heavy...

If I'm understanding what you mean...

When looking from the top, the throats are either side of the driver starting right against

the baffle. They flare out and meet the rest of the horn which runs the full length of the back of the cab. Either side of those flares there are two wedge shaped voids that are dead space. Behind the driver there is also a dead space. Bellow the driver there is a big dead space.

Look at the 3D cut away sketch at the bottom right of the plan.

I hope that makes some sense.

There was an 18" version of the Jensen Imperial built by user "Lee in Montreal". The plan was made available on the site but is no longer online. However, I saved it. Just dug it out of an old HDD. Enjoy. If there's any issue please let me know via PM and I'll take it down.

It's a gigantic box. If I could live with such a thing I'd love a pair