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PostPosted: 10 Feb 2018, 04:05 
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Hi Patrick - Of the plans provided from David I was thinking the next size up, the "1.3" (overall dimensions 32T x 10W x 10D inches). It would end up occupying about the same floor area and the AN drivers seems to work well in a bass reflex enclosure. The larger enclosure and lower tuning frequency would help extend the bottom end response of the speaker.

With the positioning in my room, speakers positioned off of the back wall, the BSC is necessary. Ideally you don't want to use a BSC and in some rooms you can get away without one with the speakers up against the wall and in the corners. The dual binding posts are a convenient way of being able to use both.

The AN drivers have a heavy cast frame basket and they don't need any damping like the stamped Fostex baskets.

Hope this helps.

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PostPosted: 10 Feb 2018, 16:16 
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It does, thanks.


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PostPosted: 11 Feb 2018, 20:32 
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Hi Folks,

As promised here are some measurements of the Audio Nirvana Classic 8 driver in the CommonSense Audio Monitor MkII Speaker Enclosure. First up is the impedance response of the speaker system. The two lines show the impedance response of the speaker system with and without the baffle step compensation (BSC) filter. The flat impedance response makes for an easy load to drive with tube amplification.
Attachment:
Classic-8-Monitor-MkII-Impedance.png

The following plots show the in-room response of the speaker system. For the measurements, the speakers were positioned at a distance of 1 m from the back wall, 2 m from each other and 2 m from the listening position. The two plots show the response both with and without the BSC filter. The response is identical with the exception of about 3dB attention from the filter.
Attachment:
AN-Classic-8-Monitor-MkII-no-BSC.png

Attachment:
AN-Classic-8-Monitor-MkII-BSC.png

In hindsight, I probably should have gone with a BSC filter closer to 6dB instead of 3dB. This is a change I will make in the future and that will help balance the bass out some more.

Overall the speakers are satisfying. They would benefit with wall loading. While the bass does not go as deep as I would like, the bass that is present is very tight, accurate and fast which is very enjoyable. A larger enclosure and lower tuning frequency would help extend the lower frequency response, but would come with other compromises.

This would be an interesting driver to try with the Fostex double bass reflex enclosure for the FE206En.


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PostPosted: 15 Feb 2018, 13:46 
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I built a pair of the 1.3 ported boxes. At 12-18" from the wall, no BSC is used and sound is excellent. The speakers sound great, from Brubeck to Pink Floyd. And my little K-12G pushes them just fine. More than fine.

I can hear each cymbal hit in Brubeck, and Echoes has more to it on top than I've heard without a ribbon. Female vocalists, e.g. Linda Ronstadt singing "What's New" with the Nelson Riddle orchestra, sound marvelous. Classic Rock soars.

Down below, these drivers do need a stronger sonic floor. Gio's measurements confirm my ears' desire for a pair of true subs at 60Hz and below. Frankly, I doubt bigger cabinets would solve the problem as effectively, although they might help.

One thing to know, these little drivers can fill quite a large space with mids and up.


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PostPosted: 15 Feb 2018, 21:31 
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Thanks for the comments Sam. I'm still fiddling with the position and do also plan to try with no BSC and closer to the wall. This is my third pair of AN drivers and will echo your comments about their excellent sonic attributes.

You are likely correct about a larger cabinet being insufficient. I have a pair of Fostex FE206E in a large back loaded horn and I would estimate the roll off in the 50Hz range and rather steep.

To satisfy my curiosity I still need to try one of these 8" sized FR drivers in a double chamber reflex enclosure to see if that will develop enough bottom. The ideal goal being just the single driver and no bsc.

Regarding the dual binding posts and BSC. In the future I think I will stick to single binding posts and keep the BSC on the outside.

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PostPosted: 18 Feb 2018, 11:12 
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So this weekend I tried pulling the Audio Nirvana Classic 8 / CommonSense Audio Monitor MkII closer to the wall. The wall loading results were quite favorable providing an appreciable lift of the lower end response of the speaker. Experimenting some more with the position I actually settled on pulling the speakers right into the corners of the room. This position resulted in the best sonics and most balanced sound from the Monitor MkII speakers.

The listening setup was:
- speakers tucked into to room corners
- speakers 2.9 m from each other and 2.9 m from listening position (equilateral triangle)
- speakers placed on ground (no stands) and tilted back towards the listening position

Below is the measured in-room frequency response of the Audio Nirvana Classic 8 fullrange drivers in the CommonSense Audio Monitor MkII speaker enclosure.

Attachment:
AN-Classic-8-Monitor-MkII-no-BSC-Wall-Loading.png


The results were excellent! The corner wall loading provides great reinforcement at about 50 Hz. In-room frequency response of about +/-5dB from across about 41Hz to 14kHz. This was with the BSC filter which is about 3dB. Without the BSC filter the response remains sufficiently balanced (+/-6.5dB) for those who would prefer not to use one. With the proper room placement, the overall response of the speaker is pretty good for a single 200 mm fullrange driver.

It's overcast today so I will get a photo posted with the setup in the next day or so.


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PostPosted: 28 Mar 2018, 22:10 
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Attached is a photo showing the Classic 8 / Monitor MkII Speakers sucked into the room corners. The microphone response for this positioning is shown in the previous post.
Attachment:
Audio-Nirvana-Classic-8-Monitor-MkII-Speakers.jpg

I have been really enjoying these speakers and have yet to switch back to the large open baffle speakers. It's a good reminder that simple systems can still sound good.


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PostPosted: 26 Apr 2018, 09:56 
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Those looks really neat! I really dig the finished wood look. Do you know how many hours in total did You spend on completing these, like at least an approximate, perhaps?

Gio wrote:
Attached is a photo showing the Classic 8 / Monitor MkII Speakers sucked into the room corners. The microphone response for this positioning is shown in the previous post.
Attachment:
Audio-Nirvana-Classic-8-Monitor-MkII-Speakers.jpg

I have been really enjoying these speakers and have yet to switch back to the large open baffle speakers. It's a good reminder that simple systems can still sound good.

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PostPosted: 29 Apr 2018, 09:30 
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Hi. The amount of time likely will boil down to the joinery chosen and how many clamps you have. I only used glued joints (no fasteners) and could only work on gluing one piece at a time due to number of wood clamps, so there was much time wasted with start-up and stopping many times over between glue drying. I probably spent about 40 hours total, but this was my first nice looking and finished speaker box built 100% on my own and using my own tools.

But if you use a brad nailer and glue, it can be built rather quickly depending on skill level. The speaker are 24" tall so you can get the lumber yard to cut you the plywood in the widths you need in 48" lengths. That will make the plywood easy to move around and then you just need to cut the pieces in half with a sled on your tablesaw. A skilled builder would likely spend less than 8 hours.

Cheers

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PostPosted: 10 May 2018, 12:09 
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Hello Gio! Nice project, i'd love to know the results of your measurements! does it match to the calculated frequency? I had some issues with a pair of helmholtz resonators exactly the same dimentions but resonating to different frequencies, i'm thinking the wood is the problem, i used the same wood in both but maybe they dont have the same density. Any thoughts?
My other question is about the insulation material, did you use mineral wool only? would you recommend an alternative material?

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