Cab Builder Question

[billfitzmaurice]

Originally Posted by dhsierra1

I'm sure this varies a lot based on cabinet design, size, bracing scheme, etc but is there a certain frequency (range) where you lose the effect of coloration?

In the vicinity of 500Hz. With bass cabs the energy content drops drastically above that, while it peaks down around 100Hz. Guitar is very different, their energy peaks in the vicinity of 300Hz. Some guitar cabs use thin unbraced plywood to accentuate lower midrange resonance, which can sound good with guitar but would be abhorrent with bass.

[andertone]

doesn't Andy at Acme cabinets use bracing that actually flexes the panels? He does this for a reason, what is it?

[will33]

Originally Posted by andertone

doesn't Andy at Acme cabinets use bracing that actually flexes the panels? He does this for a reason, what is it?

Purposely put tension on the panels so they're "stretched" even tighter, thus even more resistant to vibration from long excursion drivers. It works, don't know if it's necessary.

[billfitzmaurice]

Originally Posted by andertone

doesn't Andy at Acme cabinets use bracing that actually flexes the panels? He does this for a reason, what is it?

If you put panels in a state of flex it increases their vibration resistance. With enough flex you can greatly reduce the panel thickness, therefore weight. That's what allows me to use 1/8 inch plywood in many of my designs.

[dhsierra1]

Originally Posted by billfitzmaurice

Some guitar cabs use thin unbraced plywood to accentuate lower midrange resonance, which can sound good with guitar but would be abhorrent with bass.

Thank you

Funny, this comment reminded me of a few pp in the old Badmaieff and Davis "How To Build Speaker Enclosures" from 1966 (yes, I read it as a lad when it came out, my dad was an audiophile DIYer) where they picture and describe a home speaker system with enclosures that were two giant concrete and brick openings built into the sides of a large fireplace, each loaded w/two Altec 803b's No resonating cabinet sides there

[Philonius]

In my former life as a cabinetmaker, I worked on Studio X in Seattle. About Studio X Seattle

The control room had a monolithic poured concrete wall separating it from the main studio. Built into that structure were bass speaker wells in the floor and boxes above to house other drivers. Not much flex there.

[INTP]

@dhsierra1

I have the 1987 printing of that book. It reads:

"In this system, performance was given first consideration, and as a result the entire living room in the home was specifically designed to house and acoustically enhance the musical system. Approximately 300 cubic feet were allowed for each 25-ton enclosure. The enclosure dimensions are 4ft x 4ft x 18 ft. Three of the walls of the enclosure are solid concrete. the fourth or front wall of the enclosure is of 1-inch plywood reinforced with random diagonal bracing. Obviously, the enclosure is meant to house a musical reproduction system and not to contribute tones of its own manufacture."

[will33]

Originally Posted by INTP

@dhsierra1

I have the 1987 printing of that book. It reads:

"In this system, performance was given first consideration, and as a result the entire living room in the home was specifically designed to house and acoustically enhance the musical system. Approximately 300 cubic feet were allowed for each 25-ton enclosure. The enclosure dimensions are 4ft x 4ft x 18 ft. Three of the walls of the enclosure are solid concrete. the fourth or front wall of the enclosure is of 1-inch plywood reinforced with random diagonal bracing. Obviously, the enclosure is meant to house a musical reproduction system and not to contribute tones of its own manufacture."

Is this house for sale by chance?

[dhsierra1]

Originally Posted by INTP

@dhsierra1

I have the 1987 printing of that book. It reads:

"In this system, performance was given first consideration, and as a result the entire living room in the home was specifically designed to house and acoustically enhance the musical system. Approximately 300 cubic feet were allowed for each 25-ton enclosure. The enclosure dimensions are 4ft x 4ft x 18 ft. Three of the walls of the enclosure are solid concrete. the fourth or front wall of the enclosure is of 1-inch plywood reinforced with random diagonal bracing. Obviously, the enclosure is meant to house a musical reproduction system and not to contribute tones of its own manufacture."

LOL, I was just reading that after I posted Yeah, when I was a kid I dreamed of having speakers like that in my music room. Well, I do have my speakers near the fireplace now, but they're a little more modest than 300 cu ft concrete behemoths (ADS L1530s), no complaints, though

[dhsierra1]

Originally Posted by will33

Is this house for sale by chance?

aw, c'mon Will, we all know you have the DIY bug bad, why not build your own?

[will33]

Originally Posted by dhsierra1

aw, c'mon Will, we all know you have the DIY bug bad, why not build your own?

Of course....300 cubic feet and 25 tons can't be good enough....must be improved upon.

Cheers to all....off to the gig now.

[will33]

With 4 cu.ft. and a Peavey amp...all of which weighs less than me.

[dhsierra1]

Originally Posted by will33

Of course....300 cubic feet and 25 tons can't be good enough....must be improved upon.

I'm thinking some sort of masonary Klipschorn design on steroids would do the trick

[edwinhurwitz]

Originally Posted by Philonius

THIS is why I love Talkbass. Sand filled cabinets? They must have weighed a ton. For FOH PA's, or audiophiles gone 'round the bend?

Resurrecting an old thread. I had a pair of Wharfedale cabs from the 70s that did this. They were home stereo speakers and were quite heavy and sounded pretty good. They were a sealed design. I kind of miss them.

Also, the Grateful Dead used a PA based on sand filled speaker cabinets that were like a huge home hifi. This was for their first east coast tour after decommissioning the Wall of Sound in 1976. I saw one of those shows at the Boston Music Hall and it sounded phenomenal. Powered by large Sansui amps, it was very clean and very loud. Like many of their experiments back in the day, I'm not sure that it was all that practical or cost effective, but for the audience it was a treat.

[jimo]

ON the Tl606---It looks like the plan just shows this board at 2/1/2 inches long, but all the pictures of peoples cabs have it extended much deeper into the cab??? What is the deal??..(I am using the Emenence 3015 ...no (LF)).

[BogeyBass]

Originally Posted by jimo

ON the Tl606---It looks like the plan just shows this board at 2/1/2 inches long, but all the pictures of peoples cabs have it extended much deeper into the cab??? What is the deal??..(I am using the Emenence 3015 ...no (LF)).

the TL606 port is is designed to have 2 different tune frequencies

normal mode at 55hz and step down at 40 hz

so the length of that small 2.5 inch port shelf is necessary to obtain both.
to lower the frequency to 40hz you simply would reduce the port opening with the port cover shown in the plans to obtain the stepdown of 40hz

the actual port frequency of the TL606 is closer to 62hz than 55hz and in stepdown mode is closer to 48/50hz rather than the 40hz in stepdown mode. yes it is a rather short inaccurate shelf

In your case you should just run the lower 40hz for the 3015
the actual volume of the TL606 is 3.2 cubic feet.

The BB4 alignment for a 3015 is very close to that at around
2.9 cubic feet with a port tune of 44hz. which is the Fs of the driver as well. Common for a BB4 is to set Fb to the Fs of the driver.

So in your case the old outdated TL606 could be updated for the 3015 simply give yourself more port area by leaving the stepdown cover off, and calculate and modify the length of that shelf to give you 44hz for the 3015.

again giving you good power handling and a very close match to a BB4 alignment for the 3015 with 3.2 cubic feet and 44hz tune frequency (Fb)

adding a inch or so to the depth of the cabinet wont hurt either to get a little more bass response, and also bring the front baffle a little more forward to increase the internal airspace from 3.2 to around 3.5/3.7 and still keep the 44hz port tuning.

[jimo]

I got it!!! Thanks, I thought I was reading the plans wrong....!!! MUch appreciated!!!