Helium - a true micromonitor

[Leroy R]

Re: Helium - a true micromonitor

Do you have a sketch of the baffle layout dimensions? (Driver and port locations)

[scottsehlin]

Re: Helium - a true micromonitor

Nicely done, as always, Scott. Wish I'd gotten to hear them at Iowa. I'm curious about the choice of ND91. I've used the ND90 lots of times and wonder what the tradeoffs are.

Admittedly the ND91 is more expensive (when it is not on sale), so that is a very good question. The ND90 can be pushed very low if you can give it a little larger ported box, but the ND91 is nearly ideal in that small (1 liter-ish) enclosure I was targeting. That fact, along with the extra excursion comes in handy when you are at a hotel room full of audio geeks and someone (not naming any names ;) is throwing bass tracks at it. It should also help support a little lower sub crossover point for HT use.

If we stretched the height or depth of the enclosure by a couple of inches, I think the ND90 would start to come into play. I have some older Aura NS3's in an enclosure like that and get nice extension.

Another tradeoff to consider: For the flatpack I used, one can almost get an ND105 in there (cutout is 3.66" in diameter, internal cabinet width is 3.5"). In theory, that would do about 80Hz sealed and would handle quite a bit of power....

[scottsehlin]

Re: Helium - a true micromonitor

Getting into my 'shoehorning' territory there, Scottie! Close to a liter per cab creates some interesting dilemmas doesn't it? Parts selection is also kinda fun.

My Audinum, Xenum, and PC are all in this category, as well as Mark65's 'Dadiels', and cjd's 'Pecorino'; All have interesting solutions to the miniscule at hand.

Later,
Wolf

It seems a lot of my recent projects have veered toward the shoehorning territory. Hafnium was one of those where everything was where it was because that was the only way it was going to fit - but this project took that to even another level. Certainly, your projects helped provide inspiration along with the usual WAF considerations. I remember the first time I heard your PC's in the Grinnell auditorium and was amazed as I thought that they sounded like real speakers - even in that huge space.

[scottsehlin]

Re: Helium - a true micromonitor

Do you have a sketch of the baffle layout dimensions? (Driver and port locations)

My goal is to get that posted this weekend.

[andykriech]

Re: Helium - a true micromonitor

Hopefully with the port dimensions, too.
this is going to be a great little desktop speaker.

thanks, Andy.

[bkeane1259]

Re: Helium - a true micromonitor

That fact, along with the extra excursion comes in handy when you are at a hotel room full of audio geeks and someone (not naming any names ;) is throwing bass tracks at it.

Wait a minute......Um.....oh that wasn't me. I was pushing it in the dining room.

Ok, there. I feel better now.

[craigk]

Re: Helium - a true micromonitor

That fact, along with the extra excursion comes in handy when you are at a hotel room full of audio geeks and someone (not naming any names ;) is throwing bass tracks at it.

where were you at when this occurred ? I do not know anyone at the DIY events I have been to that would do such a thing. :D

[theLinks]

Re: Helium - a true micromonitor

At least Brian, you were in the dining room , unlike 2:30 in the morning in my hotel room! lmao
These are looking great lil speakers!

Wait a minute......Um.....oh that wasn't me. I was pushing it in the dining room.

Ok, there. I feel better now.

[bkeane1259]

Re: Helium - a true micromonitor

At least Brian, you were in the dining room , unlike 2:30 in the morning in my hotel room! lmao
These are looking great lil speakers!

You'll never let me live that one down will you, Tim? Can I make it up to you in two weeks? I'll buy you a beer.

[theLinks]

Re: Helium - a true micromonitor

No, :D

[bkeane1259]

Re: Helium - a true micromonitor

No, :D

****er

[andykriech]

Re: Helium - a true micromonitor

Hi Scott,

I am interested in the dimensions and port size as well.
Planning on building a set for my desk at work, now that I sold my set of Wolf's PCs to a co-worker.

Thanks, Andy.

[Naught1]

Re: Helium - a true micromonitor

Hi Scott, thanks for sharing your work! Very nice.

Would you please post the port dimensions?

I have a really similar project using the ND91-4 in a 5"x3.5"x5.5" (HWD) enclosure, currently using a 1"IDx4" port. Results are disappointing, because there's this broad hump in output between about 125-400hz. Changing port length hasn't tamed it, and tweaking the BSC circuit isn't helping.

Then again, I don't have a tweeter yet, and to my ears the ND91-4 really needs it. I can imagine that the midbass hump might be a lot more acceptable with some actual high end output to counterbalance it.

Cheers again for posting your project.

[randyohoh]

Re: Helium - a true micromonitor

The port looks to be a piece of pvc pipe. The tweeter is 32.5mm (1.279) in diameter and the port is "somewhat" smaller. My guess is that the port is 3/4" pvc pipe (1.050 OD - .804 ID) x at least 1/2" long. This might give a starting point.

This is a very interesting project as the foam surrounds on my old Energy Take Five are starting to give out.

[scottsehlin]

Re: Helium - a true micromonitor

The port is 3/4" pvc. There are two straight sections and an elbow (which barely fits in the box). I'll check the length of the straight sections tonight, but the tuning frequency should be between 65 and 70 Hz. Total length is about 6.5"-7".

The project can be built as posted, but lately, I've been listening with an added 40 ohm resistor across the terminals of the tweeter, which knocks down the highs by about a dB and like that a little better. Dayton has a 39 ohm 5 watt Xicon resistor that would be a good choice for that addition.