Helium - a true micromonitor

[scottsehlin]

Re: Helium - a true micromonitor

The circle is the amplifier. Your connection with that is the terminal cup. Anything with a ground symbol should connect back to the negative terminal (usually black). The non-ground side is the positive terminal (usually red). One can connect the ground points to each other, then send one wire from one of the ground points back to the negative terminal.

[Chris Roemer]

Re: Helium - a true micromonitor

And the "S" (turned on its side) is just a std. symbol for an AC signal, which music is (it's actually depicting one cycle of a sine wave).

[Mike Burke]

Re: Helium - a true micromonitor

Thanks Chris,
I understand it now, and learned a couple things to boot. Thanks

[garychelette]

Re: Helium - a true micromonitor

Will the baffle layout be the same for the new design? My only issue with the original is the extreme (to me) offset of the tweeter and the port on the front right next to it. I don't make grills (I suck at making them look nice) and my wife has flat out said "No" to this design with this layout.

Same box and everything , yes. Mod to the Xover.

[garychelette]

Re: Helium - a true micromonitor

Got the Xover parts in, but not all. Got to wait for the rest of the shipment.
Placing the 1.8 mH coil in that tiny box is a chore. The rest is good. Found a small .2 mH 22ga Ferrite core inductor that is small and cheap!
PE part # 269-2116. Don't know how many they have so I got 4 in case I make another pair.

[garychelette]

Re: Helium - a true micromonitor

Will the baffle layout be the same for the new design? My only issue with the original is the extreme (to me) offset of the tweeter and the port on the front right next to it. I don't make grills (I suck at making them look nice) and my wife has flat out said "No" to this design with this layout.

Have you tried to paint the white port? Make it blend in? That's what I will do.

[scottsehlin]

Re: Helium - a true micromonitor

For my build, I wound up painting the ports black. I spray painted down the port and painted over the end closest to the baffle with duratex.

[fastbike1]

Re: Helium - a true micromonitor

I think the slot port correction is 1/2 the port height added to the length, which would make actual tunings lower than calculated.

[garychelette]

Helium II , I'll be posting my reviews tomorrow. Just finnished them tonight and giving them a once over. Sound very nice!
More to come.

[scottsehlin]

Looking forward to your review Gary. It will be nice to have a proven 8 ohm option.

[garychelette]

OK, It's been awhile and as many here have often stated, life gets in the way sometimes. For me it's been an illness, but I'm much better now.
Now my impressions of the 8 Ohm Helium II.

To begin with, I have not heard the 4 Ohm version for the Helium so I will have to judge it as it is. I can compare it to the Quarks I have built and give my comparison to it.

#1. The ND91-8 is an 8 ohm, 30 watt RMS driver with a frequency response of 70 to 17,000 Hz. with a sensitivity of 82.1 dB. I started off on a nice little T-amp to listen to a few of my known songs to see how it would respond.
This is not a driver that goes well on an amp that is only an output is 18 watts @ 4 ohms. Being 8 ohms 82 db driver, it was a bit lacking on power. So I hooked it up to my Harmon Kardon at 50 watts RMS to see if I could get the volume up.
The Helium II seems to improve well with a little more power and even better with a little boost in bass. The tiny ports were pumping a lot of air with no hissing or noise.

#2. The ND16FA-6 tweeter gave the speaker the sparkle it needed but was not in anyway over powering.

#3. The .04 CuFt box was just enough for both speakers and cross over but not much else. Very tight fit. The box did it's job with no problems in construction. (Denovo Audio Knock-Down MDF 0.04 cu. ft. Micro Bookshelf Speaker Cabinet )
The port was made out of PVC Schedule 40 pipe with an elbow so it would fit into the box.

Note: Everything is the same as the 4 ohm Helium. Just the ND91 and the crossover has changed.

Where as the Quarks sounded a bit crisper and a bit more volume (85db vs 82db for the ND91) the H2 had more bass and longer tonal quality than the Quarks. Funny that it sounded best playing Country and Western music or New Age music than Hip Hop.
Bass drum on Hip Hop or Rap sounded more like thumping on an old oatmeal box. String bass sounded natural though.
It depends of the type of music you like to say if the H2's will fit your bill.
It does like a bit more power than the Quarks. I would say 25 - 50 RMS would provide the kick it needs as long as you don't over drive the little guys.
As you can see in the photo, I set them up off the table and listen to them sans reflection. They would improve on a desk for more bass and volume.

Over all, I liked the H2's for the nice bass and clean sound that comes out of the little box and driver. It was smooth and easy to listen to.
As long as you are not looking for mass amount of volume, these would do great in a small bedroom or dorm.
They also my make a good back surround speaker for amps needing an 8 Ohm load. Just remember not to drive them too hard.

I want to thank Scott for modeling the crossover for me and giving me encouragement along the way. Without his help, I'd be making a boring single speaker and no Xover box that would not have done as well at all. Thanks Scott!

** 04/22/22
Just wanted to pop in here after all these years and say that my 8 ohm Helium's are still serving as my computer speakers! I have added a Dayton 6" Classic Sub and a 100w Yung plate amp. The setup is great! Better than a store bought setup any day! Hope we can keep this little guy alive and keep people building!

Gary - Somerville Texas

[garychelette]

Bump!

[whatabirdie]

Congratulations for your nice build and thanks for the review. They look good in duratex

[garychelette]

Congratulations for your nice build and thanks for the review. They look good in duratex

I guess almost anything looks good in Duratex.

[CZ Eddie]

Whoah.... I'm totally building one of these for my bar speaker project!

Since I'll be using a single one of these firing straight up on a table with no boundary near by, with the table in the middle of a very wide open large room, should I incorporate a BSC? Maybe 3dB boost in the bass?
Also, how much power can these take? I've got a 60W amp but am totally willing to find something with more power since this speaker will absolutely be taken to it's limits!

Yes, I know this is the wrong speaker for my needs.
Large, open room, etc.
But please bear with me, I know what I'm doing and this fits a very specific need.
I've already got an NS3 in a crap box doing 90% of what I need.