Helium - a true micromonitor

[Herman Trivilino]

Re: Helium - a true micromonitor

Having built and listened to both I would say that because the OS go lower I can listen to them without a sub. The Heliums need a sub for the listener to be able to hear the same low frequencies. But the Heliums are smaller in size so visually they disappear into my living room decor better.

It's all about how your speakers appear and sound. Sound is important, but so is appearance.

[arrayed]

Re: Helium - a true micromonitor

thanks! makes sense. I do like the 'tiny' heliums.

[scottsehlin]

Re: Helium - a true micromonitor

I was researching woofers to use with the new Dayton Mini-AMT and I remembered this design. It seems to me in theory that you could drop the Mini-8 AMT in place of the tweeter. A 5Khz crossover point looks to be nearly ideal for the AMT. Anyway, just a thought. I know this design is good to go as is.

I do think that the Mini-8 could be mated with the ND-91 - and that would have a lot of potential. The sensitivity is similar to the ND-16 used in the Helium, but in looking at the response plots I would guess the filter on the tweeter would change a lot. The ND-16 has a lot more output in the 2 kHz to 5 kHz region than the Mini-8 does. So I would consider it a new design rather than a drop-in. Dayton made their B652 the B652-Air, but Helium-Air just doesn't quite sound right. Maybe Liquid Helium, or Heliox?

Also, I know the Mini-8 is small, but it isn't as small as the ND-16. One would have to make sure it would fit on the baffle.

Cost was certainly a consideration in the tweeter choice. The ND-16 saves you $20 per speaker, which becomes significant if one were to build 5-7 of these for surround sound.

[Herman Trivilino]

Re: Helium - a true micromonitor

For anyone struggling to build the crossover by looking at the schematic, here's a picture of mine. From my fifth Helium build. This one is destined for center channel duty. Soon 5 of the speakers in my 5.1 living room system will be Heliums.

The inductors at the top and bottom are from Dynavox.com. The rest of the parts are from PE. I would have used the smaller NPE caps but PE was out of the sizes needed.

[djkest]

Re: Helium - a true micromonitor

For anyone struggling to build the crossover by looking at the schematic, here's a picture of mine. From my fifth Helium build. This one is destined for center channel duty. Soon 5 of the speakers in my 5.1 living room system will be Heliums.

The inductors at the top and bottom are from Dynavox.com. The rest of the parts are from PE. I would have used the smaller NPE caps but PE was out of the sizes needed.

[ATTACH=CONFIG]54698[/ATTACH]

That's excellent, thanks for posting.

ETA: Are they (dynavox choke coils) really 0.5 ohms? That seems rather high for the DCR.

[corradizo]

Re: Helium - a true micromonitor

Could these be put into a wall as an inwall? Otherwise could the go on-wall?
I need to do something really WAF friendly for the bedroom wall mounted lcd.

[Herman Trivilino]

Re: Helium - a true micromonitor

It seems I measured the DCR of the 1.0 mH inductor and posted it earlier in this thread. I can't remember.

Their website lists the DCR of the 0.2 mH inductor as 0.5 ohms. That does seem a little high but now that mine is installed I have no way to measure it.

I plan on recessing my Helium center channel into the wall. Just build a box around it of the correct volume.

[djkest]

Re: Helium - a true micromonitor

Could these be put into a wall as an inwall? Otherwise could the go on-wall?
I need to do something really WAF friendly for the bedroom wall mounted lcd.

Paul Carmody has designed some OS variants for near-wall use. These have baffle step compensation so they will be heavy in bass and midbass if used on a wall. Scott can fill you in on more details.

[Mike E]

Re: Helium - a true micromonitor

im kinda surprised this isn't offered as a kit on PE yet.

[johnnyrichards]

Re: Helium - a true micromonitor

im kinda surprised this isn't offered as a kit on PE yet.

I think the necessity for tiny coils kind of puts it out of PE comfort zone. I agree, it would make a great kit - but so would any number of other small 2-way speakers.

[Herman Trivilino]

Re: Helium - a true micromonitor

Could these be put into a wall as an inwall? Otherwise could the go on-wall?
I need to do something really WAF friendly for the bedroom wall mounted lcd.

Paul Carmody has designed some OS variants for near-wall use. These have baffle step compensation so they will be heavy in bass and midbass if used on a wall. Scott can fill you in on more details.

My recessed center channel Helium will probably stand 1.5 inches proud of the wall surface. I plan on cutting a hole in the wall and inserting the cabinet. The cabinet depth is 5.0 inches. I'll have a hole of depth 3.75 inches, but I'll need a quarter inch at the back for the speaker wire.

I'll post pictures when I do it. Hopefully this weekend.

I hope the Audyssey equalization will undo the baffle step compensation.

[scottsehlin]

Re: Helium - a true micromonitor

I think the necessity for tiny coils kind of puts it out of PE comfort zone.

I agree, although I don't know what PE sources for some of their lower cost completed speakers like the B652, B452, etc...

My recessed center channel Helium will probably stand 1.5 inches proud of the wall surface. I plan on cutting a hole in the wall and inserting the cabinet. The cabinet depth is 5.0 inches. I'll have a hole of depth 3.75 inches, but I'll need a quarter inch at the back for the speaker wire.

I think this will work okay. The ND-91 tends to have a bit of a dip in the response in the baffle step region. You will probably have some peaking below that, which plugging the port may solve if needed.

[bkeane1259]

Re: Helium - a true micromonitor

Scott - Can this be used for the big inductor? I just ran across these at PE - http://www.parts-express.com/ferrite...-watt--269-303


They say the core can be pulled out, yielding a 1mh air core coil. Thoughts?

[Herman Trivilino]

Re: Helium - a true micromonitor

I think it would fit in the cabinet.

[scottsehlin]

Re: Helium - a true micromonitor

You would be upping the DC resistance a little (from 0.5 mH to 0.88 mH), but the effect would be pretty minimal for this design. I would feel comfortable using the buyout coil (core removed of course).