Advice on enclosure

[Cool Hand Luke]

Hi Everyone,

After spending the last month or so trying to glean information from here and other forums, im still a bit confused about what enclosure to use with the Audio Nirvana 8 inch drivers i just picked up on ebay for £140.

I am using a small logic 3 valve amp at the minute but I plan to upgrade later.

Please see below for my room layout. the room is 5 meters by 3 meters (approx 6 yards by 3.5 yards) , the blue is my couch and the two boxes indicate the proposed location of the speakers. They can be positioned either where I have indicated, or at the back wall. The floor is concrete and there is minimal furnishing in the room.

I listen to a wide variety of music, alot of which is bass driven, so I imagine that I will have to build a sub at some stage, that is fine with me, also there is a fair bit of space for large enclosures.

As for construction material I have a choice of molded concrete and marine 18mm (3/4 inch ) ply.

Pic 2 is an idea i have been toying with, using a rear loaded horn and have the sound reflect off the floor and into the room. Does this sound like a good or bad idea? Can anyone make any reccomendations for the type of enclosure that would suit?

Thanks in advance for any advice any of you would like to submit and I will try to make an interesting thread by posting pics of the build.

Luke

 

[xrk971]

If you are thinking of aiming the rear down onto floor look at the Rondo threads.. It might work with AN 8. That's a big room to fill with a valve amp.

 

[Richard Ellis]

There is/was a lot of discussion here in the forums about the seemingly variable T/S parameters of the Nirvana series of drivers. An individual noted three different sets of specifications for the AN8..........how is one to build an enclosure with no set specs???.
What sounds fishy is Audio Nirvana does not publish specs at their own web-site??

Anyway, I would put your enclosures...what ever they may be, on the long wall some 3/4 meter from the side wall, angled, toed in toward the couch on the other long wall, 1/2 meter away from the back wall. Preferably the driver/ enclosure up on stands to get the driiver at sitting ear-level.
Here's hoping you have figured out which T/S parameters to use & design from.



____________________________________________________Rick........

 

[zman01]

That's a big room to fill with a valve amp.

I think OP made a typo when he mentioned 16 yards x 3.5 yards - probably he meant 6 yards and not 16, as 5 meters is~ 5.55 yards.

3.5 yards x 6 yards should be ok sized room for relatively high efficiency speaker and a valve amplifier.

 

[picowallspeaker]

A triangular base enclosure ? Closed, with no thrills and frills....

 

[Cool Hand Luke]

If you are thinking of aiming the rear down onto floor look at the Rondo threads.. It might work with AN 8. That's a big room to fill with a valve amp.

I had a look at them, they seem like they could work well for me, and thanks for suggesting, the only thing is the cabinet looks a bit more advanced than my carpentry skills would allow.

There is/was a lot of discussion here in the forums about the seemingly variable T/S parameters of the Nirvana series of drivers. An individual noted three different sets of specifications for the AN8..........how is one to build an enclosure with no set specs???.
What sounds fishy is Audio Nirvana does not publish specs at their own web-site??

Anyway, I would put your enclosures...what ever they may be, on the long wall some 3/4 meter from the side wall, angled, toed in toward the couch on the other long wall, 1/2 meter away from the back wall. Preferably the driver/ enclosure up on stands to get the driiver at sitting ear-level.
Here's hoping you have figured out which T/S parameters to use & design from.

Yeah that did cause me a bit of concern, so I was hoping to opt for a versatile enclosure that would allow me to fine tune easily. With that in mind im leaning towards a BIB, as from what I gather it can dampen the 'shout' of the AN high end, as well as produce ample bass. I will use your advice about the placement, thank you.

I think OP made a typo when he mentioned 16 yards x 3.5 yards - probably he meant 6 yards and not 16, as 5 meters is~ 5.55 yards.

I did indeed, fixed now, thanks.

A triangular base enclosure ? Closed, with no thrills and frills....

A good suggestion, and great looking, but again, probably out of my skill range to construct.

Can anyone confirm if the BIB has to be in a corner of the room or can it work well as long as its close enough to one of the walls?

Also the website that offered the BIB dimentions calculator on it seems to have shut down. I have found the following, can anyone advise if this will work with the AN8 drivers or if it will need modification?

 

[zman01]

Please refer to post #21 of the following thread for BIB calculator download:

http://www.diyaudio.com/forums/full-range/190224-enclosures-hemptone-fr8-3.html

 

[kevinr]

2.8

Audio Nirvana has spec sheets for their drivers at their web site .
The AN 8 was originally meant for the 2.8 cubic foot cabinet although they can be used in smaller ones the 2.8 is optimal.
I have the CF12 in the 2.8 but it really should be in a 5.6. They are toed in but against the back wall in a 11X15X8 room
BIB

 

[GM]

Can anyone confirm if the BIB has to be in a corner of the room or can it work well as long as its close enough to one of the walls?

Also the website that offered the BIB dimentions calculator on it seems to have shut down.

Yes, basically, there's ~3 dB less dynamic headroom, power handling, driver protection down low, so may/may not play loud enough for you at low distortion on music with significant < ~42 Hz content.

Another calculator link: http://www.diyaudio.com/forums/atta...90303-fostex-fe206e-bib-bib_166_gm_v2.xls.zip

GM

 

[Cool Hand Luke]

Please refer to post #21 of the following thread for BIB calculator download:

http://www.diyaudio.com/forums/full-range/190224-enclosures-hemptone-fr8-3.html

Thanks Zman!

Audio Nirvana has spec sheets for their drivers at their web site .
The AN 8 was originally meant for the 2.8 cubic foot cabinet although they can be used in smaller ones the 2.8 is optimal.
I have the CF12 in the 2.8 but it really should be in a 5.6. They are toed in but against the back wall in a 11X15X8 room
BIB

Thanks Kevin, i had a look and have found them. I'm pretty much settled on the BIB now, they appear to do all I need and look great at the same time.

Yes, basically, there's ~3 dB less dynamic headroom, power handling, driver protection down low, so may/may not play loud enough for you at low distortion on music with significant < ~42 Hz content.

Another calculator link: http://www.diyaudio.com/forums/atta...90303-fostex-fe206e-bib-bib_166_gm_v2.xls.zip

GM

Thank you, so would you reccomend I go inverted BIB then if I was to place the caminets that far away from the wall? I could position them at the back wall but would have to remove a large book shelf that I built, so I would prefer to have them as per my drawing in post #1

 

[GM]

Good question, don't know as I've yet to do any of these types of BIB alignment. My pipe horns were designed using a different cut-off point with a Sd = Av reflex vent and normally corner loaded, but if you prefer them away from boundaries, then floor load them and empirically find the best overall tuning [terminus/floor gap]. Worst case is you may need a loading plug, though AFAIK no one has actually experimented with one, so apparently everyone's room gain has been sufficient to meet their anticipated LF performance.

GM

 

[Cool Hand Luke]

So I have gone for a regular BIB, on further inspection the iBIB seems a bit too easy to get wrong.

Modeling the dimentions on CAD software has hilighted a bit of a problem. Reccomended Z Driver value is 32.73 inches/83mm. Using a baffle thickness of 36mm (2x 18mm Marine ply sheets, approx 3/4inch) the driver wont fit! The magnets on these things are huge!

I would have to either move the Z Driver down by 4 inches/100mm or increase baffle thickness by .4 inches/10mm

for reference the internal height is 76.8 inches/1950mm, internal width is 9 inches/228mm and depth is 13 inches/330mm

Should I increase the Z driver value or the baffle thickness to accomodate? i'm leaning towards the baffle increase as I can mill a nice thick hardwood baffle and open it up at the back..

 

[GM]

??? Drawing of what you're talking about?

GM

 

[Cool Hand Luke]

Please see attached..

 

[GM]

OK, what about mounting it on the side or is it too narrow also?

GM

 

[Cool Hand Luke]

Theres even less room to manoeuvre if I mount it sideways, not to worry, ill just increase the baffle thickness.

 

[Squeak]

Remember to chamfer well around the edges if you are using a thick baffle. And remember to do it it in a fourleaf (or however many screws are used for this driver) clover pattern so the screws have enough material to bite into. Use a rasp and round file for this as it is virtually impossible to do well enough with a handheld router. If you have access to CNC equipment that's a different story though.

 

[xrk971]

You might try using a very thin plywood or even foam core inner divider panel and curve it in an arc to make more room for the driver. This was done with some success in the Flat BIB or FIB. The slight curve changes the horn from conical-conical to parabolic-hyperbolic by a slight amount. It does not alter the character of the BIB too much and provides a lot more flexibility to mounting larger drivers. Plywood can be curved by cutting partial depth slots on the concave side. Bendy plywood that has this treatment already is also available but for the slight arc you need to clear the magnet you can do it with some slots.

 

[picowallspeaker]

Wow, XR, while reading your post about curved panels inside
( and I knew you were going to mention...foam )
And having still in mind a triangular base, I blong ( it's the past tense of : bling ! ) of an exponential duct BR .
As I recall that someone on another forum lamented for the not-so-good bass of an AN8 in a labyrinth enclosure.
So, Triangular base and exp BR with duct aperture on the rear or on the bottom
Nice catch!

 

[xrk971]

Pico,
The DNA thread appears to be an exponential duct BR and it achieves some amazingly low bass extension into 30 Hz before starting to fall of with a 5 in driver. Look in the DBLH thread and you will see a five pipe BLH speaker I am designing. I utilize a relatively large driver chamber required to provide capacitive isolation of one duct from another in order to tune them independently. But the bonus is 30 Hz bass extension with 5 in w5-1611 driver.

I still do not know how to visualize what you mean by a triangular base with a BR and exponential duct. Do you have a sketch you can provide?