Audio Nirvana Super 15 ALNICO on Large Open Baffle

[bjuck57]

Hi there fellow diy:ers!
Here is a short report and some photos from my recent build. The Audio Nirvana Super 15 Alnico on large open baffles (180x90cm) with wings (180x20cm). I have roughly 150 hours on them by now. Bass improved after about 40-50 hours and the rising midrange response was somewhat dampened after ~100 hours. I use a Behringer 31 band equalizer with +-6 dB compensation (20Hz - 20kHz). I am quite pleased with the sound this way, not really that bothered by the filter phase shifts and added noise. I use a SG 845 tube amplifier (similar to Mr. Liang's model?) which adds some muscle to the presentation. My EL34 SE amp could not control the bass notes like the SG 845 amp does. So 10-20 Watts amplification seems adequate. Well, this was a fun and interesting build. I was curious about the larger Audio Nirvana models and if they could be implemented on open baffle to achieve a fullrange presentation. With the added +-6 dB eq I think it is pretty much 'fullrange'. For my music taste (I listen to pretty bass heavy music), there is no need at all for further bass augmentation. Maybe some added treble to taste, but just maybe.

 

[bjuck57]

Some photos.

 

[Richard Ellis]

Long long ago (1981) I tinkered with OB implementations, then I closed them in for ages then re-discovered & learned more.
I recently tested some un-known drivers & got a Qts of 1.06...a bit of a un-controlled driver.....knowing baffle size will make or break the lower registers, I opted for a one square meter size baffle, coupled to the floor, it turned out just fine!
In your case of a Qts of .954 it is rather under-damped & the lower registers might sound a bit "sloppy"..........That said, a simple build on your part(One plain sheet of MDF) will be an easy "experiment"!
As bigger is better on OB, for your 15" I would get a rather giant sheet for this experiment.
Truth be told, I would get two sheets at one meter by one and a half meter in size.....yeah really big for sure..........if it sounds what your looking for, a nice big 300mm radius on the four corners would be nice.
Put the driver centered at the upper square meters worth, the bottom half meter will couple to the floor.....the driver as such will be "up" high enough, near to "ear level".


________________________________________________Rick.........

 

[bjuck57]

Thank you for your input and advice, Richard. The baffles I built are somewhat higher than you suggest. I thought about making them roughly the size you suggest, 150 cm tall instead of 180 cm tall. But I landed on building a 180 cm tall baffle, to accomodate two helper woofers (above and below the AN driver), if ever needed. But I will not do that, no helper woofers needed, I think. However, I think the eq is essential to make the representation fullrange (well, the 'fullrange' definition according to my ears )). I am attaching a photo of the eq settings I use. The scale is set to max/min +- 6 dB. I use 5 dB bass boost, midrange damped 5-6 dB, treble boost 6 dB.

 

[Richard Ellis]

View attachment 408960 Thank you for your input and advice, Richard. The baffles I built are somewhat higher than you suggest. I thought about making them roughly the size you suggest, 150 cm tall instead of 180 cm tall. But I landed on building a 180 cm tall baffle, to accomodate two helper woofers (above and below the AN driver), if ever needed. But I will not do that, no helper woofers needed, I think. I think the eq is essential to make the representation fullrange (well, the 'fullrange' definition according to my ears )). I am attaching a photo of the eq settings I use. The scale is set to max/min +- 6 dB. I use 5 dB bass boost, midrange damped 5-6 dB, treble boost 6 dB.

Beautiful build!...very pretty!!
I had always been concerned with the Dipole(?) effect of the mid to high frequencies emanating from the rear, reflecting off the back wall & messing things up, but after actually building one, I found that a non-issue.
After building my "proof of concept" version, I need to build the permanent versions, perhaps tweaking the Height to width ratios for a more aesthetic presentation. Draping sheets over them just won't do! Perhaps something resembling that big blue grill on the JBL 4350 monitors..???


_________________________________________________Rick...........

 

[kevner1954]

I have some 12 inch cast frames, that im going to OB . hope you don't mind if I steal some of your bracing techniques. not going to be EQed just a experiment for a small room and to get those 12inch audio nirvanas back in something other than their boxes, also have 10's and 8's in the 2.8 boxes. 10's I like veeeeery much thanks

 

[bjuck57]

Very cool that you find my bracing techniques and the ob design interesting! Good information from you about the 10's; I have a pair of AN10 Classic drivers that will be my next project, probably also ob but crossed over to a 15 or 18 inch bass driver in H or U-frame. Thanks!

 

[kevner1954]

one more question . I drive my 10's with a certain 45 tube amp that's maybe 2 watts. not sure it will drive the 12's in a open baffle design. also the amp does drive the frugalhorns which are 93db/w/m????? fostex drivers, enabled, if that means anything1

 

[Bigun]

I've been using a couple of Watts without issue.

http://www.diyaudio.com/forums/full-range/217893-bigun-audio-nirvana-super-15-a.html

 

[kevner1954]

with just the single driver ,in my case 12 in. cast frame driver?

 

[CLS]

I'd suggest not to boost below 30Hz. Cutting it instead.

Even though the baffle is not small, but OB would not pressurize the room anyway. So giving up the large excursion of the very LF would be a good thing - less distortion and higher headroom.

 

[kevner1954]

ok , thanks a lot

 

[2 picoDumbs]

I'd suggest not to boost below 30Hz. Cutting it instead.

Even though the baffle is not small, but OB would not pressurize the room anyway. So giving up the large excursion of the very LF would be a good thing - less distortion and higher headroom.

I agree.