Any general suggestions on this sub would be much appreciated.

[frascati]

Just received a Vifa NE315W-04 12" Neodymium Woofer at the door.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-1120

Specifications: • Power handling: 150 watts RMS/300 watts max • VCdia: 2" • Le: 0.38 mH • Impedance: 4 ohms • Re: 2.8 ohms • Frequency range: 25-1,000 Hz • Fs: 20 Hz • SPL: 88.6 2.83V/1m • Vas: 7.12 cu. ft. • Qms: 15.6 • Qes: 0.32 • Qts: 0.31 • Xmax: 9 mm • Dimensions: Overall diameter: 12.40", Cutout diameter: 11.20", Depth: 6.55".

I have on hand two of the following from the NHT sale...

WF-100K Foster subwoofer plate amplifier. 115W into 4ohms, 80W into 8ohms. 4th order (24dB/octave) low pass adjustable from 50-200Hz. 0-180 degree phase switch, RCA and speaker level inputs, volume control. Unit has a 3rd order (18dB/octave) high pass filter at 29Hz with a Q of 0.707 built into the subwoofer section. Can easily be modified for any Q and cutoff frequency that you want by changing R615, R617, R618, C607, C608 and C609. The amplifier also has a spectral tilt control that is adjusted to give about 10dB of shelving. It can be manually adjusted with a pot on the PCB. See response curves linked below. A drawing of the amplifier and schematic are both linked below. Two of these amplifiers can be bridged together to produce 220W into 8ohms. See the FAQ below for details of bridging and filter modifications. This amplifier is available in two versions. Ver1 is externally switchable between 115/230VAC. If you want this version, clearly indicate so on your order. Ver2 has a modified HP filter to extend and flatten the bass response down to about 20Hz. See the pdf files below for the measured frequency response. This version is 115VAC only.

I expect to go sealed according to the following advice regarding this Vifa driver...

If sealed, A 2 Cu Ft. box will do. If ported, 3.3cu ft. 4" dia port, 13" long for 25Hz tuning. This driver leans towards ported, but not so much that you couldn't go sealed. I don't recommend a 3" dia port or tuning below 25Hz. Tuning it below 25Hz means you lose efficiency in higher bass where most of it resides and the F3 point actually rises.

Any consensus on this? Only real criticism I've seen on this driver so far is it's low sensitivity. Should that be taken into account in the cabinet design aiming for 100 percent music, no HT, relatively low listening levels?

Since I have two of these sub amps, is it at all worth my while to combo them on this driver?

What is the current take on stuffing in subs? Understanding that it can increase the volume that the driver "sees", is it not the case that after all the numbers are run through a design program it's best to simply line the walls to absorb reflections to avoid screwing up the attention to details in the box design? (I realize exact volume is less critical in a sealed design)

Thanks for any suggestions on any of this.

[cjd]

Assuming you using this as a dedicated sub? If so, the comments about efficiency largely become moot with respect to recommended alignments - you just need to apply more power to get it loud.

Stuff to fine-tune, not to overcome intentional compromises to SQ by significantly undersizing the box. Nothing, and I mean nothing, beats the sound of a system that's not undersized. It's subtle, but very clear once you know what to listen for.

I'd have to run the numbers through Unibox or another similar tool to see where my recommendations might fall with respect to this driver.

[frascati]

Thank you. Yes this will be a dedicated sub in a sub/sat arrangement with a pair of 8in woof 1in dome sealed ADS L520 '80s vintage speakers.
They appear new out of the box, but one tweeter has some dust collected on it which does not seem to affect performance.



(link to an old brochure with specs)

http://sportsbil.com/ads/l420_l520-l620-b.pdf

I'm thinking of keeping with the thrift store ethic on these (where I got them) and finding a small end table of solid hardwood that needs refinishing and brace and seal the cavity for use as a subwoofer cabinet. I'll make my own stands for them as well.

[frascati]

Found a cabinet at my favorite thrift, St. Vincent DePaul yesterday.
Ten dollars.



It's solid oak. Not one stitch of veneer (edges of all panels are visible). Office file of some sort. Antique, but not of any collectible value beyond what I want to use it for. Nice thing about this really old oak, especially if it's been well preserved over the years by coats of paint and varnish, is that the grain is gorgeous beyond most off the shelf stuff at the big box stores. Not easy to see in this shot, but it amazingly beautiful...



All that needs done is to disassemble, sand off the finish with a vac connected orbital sander, trim four inches off of the overall height, slap on a coat of urethane, and this is what it looks like drawn to exact scale along with my present speakers..



It's 3/4 inch solid oak all around. What I'll probably do is build a sub out of 1/2 inch MDF to exact outer dimensions to fit within this cabinet's inner dimensions and glue it within. That solves my sealing, mass, and joint strength issues. I'll plan for the volume of a vented system and seal off the volume for the present sealed sub I'm planning on using. That way I'll keep the option open in the future to modify it to vented if desired. Also plan to keep the front hinges and keyhole visible, and put some books and a lamp on top to disguise it better... more invisible bass!

Any other tips for me?

[JonMarsh]

Well, the sensitivity really isn't all that bad- 88.6 dB is fairly high for a sub- but then, this isn't really a sub driver, but a wide range woofer of moderate sensitivity. Xmax at 9 mm is a bit above average for a woofer (6-8 mm is common in this size) but it's not really a subwoofer, in the sense of something like the Dayton RS315HF, for example, with a 14 mm Xmax. (for reference, I have some 12" sub drivers that are 28 mm Xmax- rather low sensitivity, but high power handling.

A response about box tuning for this was posted at PE:

It will do well in a 1 to 2 cu ft sealed or 2 to 4 cu ft vented enclosure tuned to the mid to low 20's. In the 1 cu ft sealed your F3 is ~50 Hz, 2 cu ft sealed F3 is 45 Hz, 2 cu ft vented tuned to 25 Hz gives an f3 of 34 Hz, in the 4 cu ft tuned to 25 hz your f3 is 25 hz. I would not recommend running it with any more then 100 watts in the larger enclosures to prevent over excursion, and be sure to use a subsonic filter if going the ported route.

Keep that information in mind when working on your box design or adaptation.

Where this driver would excel is more in a conventional three way; pretty smooth response and low distortion up to 1 kHz due to the neodymium motor assembly with underhung voice coil. It does have a pretty strong peak in the 2-3 kHz area.

[frascati]

Thank you Jon for weighing in. I've already purchased and unboxed this driver. It was 115 on sale. This is the only application I anticipate for it. This sub is for 100 percent music, at relatively low levels. It will not be used in a HT.

Before I get too demoralized and return/exchange this for a Dayton 12inch based on your assessment, may I ask if you think that, within the limits of its excursion, there is any reason to think it would not do subwoofer duty equal to the Dayton driver? It would seem to have the freq response and Fs for the task. It will be in a sealed box with a 100watt plate amp.

[5th element]

According to the limited measurements I've seen, the NE range appear to have very linear motors. Not sure how well they'd cope with being over driven, but providing they are used within their capabilities then there's the possibility that they could even be better then the Dayton.

[Bear]

One has to love the Nd pricing issues. These are $115 at PE and over $300 at Mad.

[JonMarsh]

Thank you Jon for weighing in. I've already purchased and unboxed this driver. It was 115 on sale. This is the only application I anticipate for it. This sub is for 100 percent music, at relatively low levels. It will not be used in a HT.

Before I get too demoralized and return/exchange this for a Dayton 12inch based on your assessment, may I ask if you think that, within the limits of its excursion, there is any reason to think it would not do subwoofer duty equal to the Dayton driver? It would seem to have the freq response and Fs for the task. It will be in a sealed box with a 100watt plate amp.

As a music sub for the speakers you've shown, it should work fine. I'd suggest considering the larger sealed alignment, or using a high pass filter carefully with the ported alignment, so as not to overdrive it in the very low frequency range.

The price is certainly right for this driver at PE.