Helium - a true micromonitor

[scottsehlin]

I agree, not exactly a Helium - but an adaptation that will make sense for certain applications. I am curious as to how close the ND90 is as a drop-in to the ND91 from a crossover perspective. Looking at the graphs, the ND90 seems to have a few dB higher output above about 1.5 kHz. The ND91 has a breakup peak around 15 kHz that the ND90 doesn't show. As Jake suggests, this might wind up helping to balance the increased bass output that the ND90 will have in his enclosure. The Helium design as it is really is more of a balanced design than a perfectionist design due to the simple fact that small size and full-ish sound are top priorities. There is very limited space for port tubes and crossover components.

From a more conceptual standpoint, I have played with a few ND90 designs. For bass and box size, I wind up coming back to the ND105 as something I can get similar extension out of in the same enclosure size, but with more output capability due to the larger cone. The one thing that the ND90 does better is higher frequencies. So, if I get around to an ND90 design, it will probably be with something like one of the small AMT tweeters (the Mini-8 or the Pod-4) that really need to cross around 5 kHz.

[doom]

Hi all, a very good and necessary project, I really liked it, does anyone have the video or whether listening to music without YouTube? Case I already have ready, I want to repeat this life hack ). Price really delivery is not very adequate $152, so I think justify whether these speakers are such a cost?

[Jake]

Doom, I think you can build this cheaper than your estimate. You can buy a single 2x2' mdf board at lowes or home depot for $6, you can also buy the pvc pipe used for the port there. Much cheaper to build your enclosures. Also you can use bp electrolytic caps instead of poly, or just use a poly cap on the tweeter and electrolytic on the driver. Cost should be around $100. Definitely worth that price any day.

[doom]

box to me already almost ready, now the price goes.
Products (12)

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	Parts Express Recessed Speaker Wire Terminal Cup Banana 5-Way Binding Posts Part # 260-303	2	$6.98
	Speaker Cabinet Port Tube 1" ID x 4" L Flared Part # 260-470	2	$3.96
	Dayton Audio ND91-4 3-1/2" Aluminum Cone Full-Range Driver 4 Ohm Part # 290-224	2	$46.00
	Dayton Audio 1.0mH 18 AWG Perfect Layer Inductor Crossover Coil Part # 257-826	2	$14.46
	Dayton Audio DMPC-4.0 4.0uF 250V Polypropylene Capacitor Part # 027-421	2	$3.90
	Dayton Audio DMPC-2.0 2.0uF 250V Polypropylene Capacitor Part # 027-414	2	$3.22
	Dayton Audio DNR-2.0 2 Ohm 10W Precision Audio Grade Resistor Part # 004-2	2	$2.76
	Dayton Audio DNR-7.0 7 Ohm 10W Precision Audio Grade Resistor Part # 004-7	4	$4.36
	12 Ohm 5W Resistor Wire Wound 5% Tolerance Part # 015-12	2	$1.36
	27 Ohm 5W Resistor Wire Wound 5% Tolerance Part # 015-27	2	$1.36
	Dayton Audio ND16FA-6 5/8" Soft Dome Neodymium Tweeter Part # 275-025	2	$10.00
	Dayton Audio 0.20mH 20 AWG Air Core Inductor Crossover Coil Part # 257-024	2	$5.82

[doom]

here's a box of 200 grams more than 0.04 feet, I want to make the port top and the bottom to put a sack of sand, 200 grams, would that be a solution?

[Jake]

If your spending the money, I would not use those boxes. Buy the flat pack, or make your own from a 2'x2' piecell of mdf

[Millstonemike]

here's a box of 200 grams more than 0.04 feet, I want to make the port top and the bottom to put a sack of sand, 200 grams, would that be a solution?

First time I saw a metric tape measure

[doom]

Sometimes everything in life happens for the first time.

[jwjarch]

More than a few months late, but I finally put the finishing touches on my Heliums. My wife can't say enough about how much she loves the looks AND the sound. They're the newest addition to our master bedroom. Thanks again for the great design Scott!

[doom]

Beautifully made, the speakers, behind another picture to see if it is possible?

[jwjarch]

Thanks doom! I was so excited about the fronts that I forgot to take photos of the backs. I'll take some when I get home tonight and post.

[jwjarch]

Here are a few photos of the back of one speaker. The ports are mirrored on each side.

[doom]

very cool, respect)
a couple of minutes of recording music by listening would be like.
How many time have built these speakers?

[jwjarch]

Thanks doom. This was my first real speaker project. But I have years and years of woodworking experience.

[doom]

jwjarch
Clear, and photos of the construction too can check out?
How many days did they?
Or the box was purchased?

The best product I have ever seen !