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Helium - a true micromonitor

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  • Naught1
    replied
    Re: Helium - a true micromonitor

    Originally posted by scottsehlin View Post
    Yes, 3/4" ID on the PVC. I have not heard any port noise and it wasn't for lack of trying :D The bass is rolling off pretty steeply below 60 Hz, which I think is helping.
    Thanks for clarifying. Good to hear that port noise won't be an issue ;. If you pushed it, then my wee little SMSL SA-S1 shouldn't pose a threat. Cheers!

    Leave a comment:


  • Zephyr
    replied
    Re: Helium - a true micromonitor

    Just wondering if the new 11.00 Dayton ribbon tweeter would have any advantages in this application. http://www.parts-express.com/dayton-...6-ohm--275-083

    Leave a comment:


  • bkeane1259
    replied
    Re: Helium - a true micromonitor

    Originally posted by scottsehlin View Post
    Yes, 3/4" ID on the PVC. I have not heard any port noise and it wasn't for lack of trying :D The bass is rolling off pretty steeply below 60 Hz, which I think is helping.
    I'll second that since I was sort of involved in pushing these tiny puppies in Grinnell. Great little speaker.

    Leave a comment:


  • scottsehlin
    replied
    Re: Helium - a true micromonitor

    Yes, 3/4" ID on the PVC. I have not heard any port noise and it wasn't for lack of trying :D The bass is rolling off pretty steeply below 60 Hz, which I think is helping.

    Leave a comment:


  • Naught1
    replied
    Re: Helium - a true micromonitor

    Originally posted by scottsehlin View Post
    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".
    Ahah, thank you! That's almost twice as long as I tried. And it makes sense considering what I was hearing. I was trying to keep a straight 1"ID to reduce port noise, but I see now that might be a pipe dream. The ND91-4 can move a lot of air, but I guess you didn't have any trouble with port noise?

    Do you mean 3/4"ID PVC?

    I found that with such a small box, it's a real trick to keep the inside port opening from being jammed against the walls.

    Parts on order to try out your x-over and tweet solution in my project.

    Leave a comment:


  • scottsehlin
    replied
    Re: Helium - a true micromonitor

    That will work. I see that Dayton doesn't have a 14 ohm resistor, but 15 ohms is close enough. For caps, I used the dynavox 4uF met. poly and a surplus met poly 2uF capacitor from Madisound. The NPE's you chose should be okay. You could pick up the Dayton 027-414 for something similar for the 2uF... The NPE's will make it easier to fit the crossover in the box and you probably won't hear any difference.

    Leave a comment:


  • flyfishingnitin
    replied
    Re: Helium - a true micromonitor

    Here is a shopping cart. Can Scott or someone you please confirm?
    Click image for larger version

Name:	PE_Helium_Shopping_cart.jpg
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ID:	1162335
    Click image for larger version

Name:	Dynavox_Helium_shopping_cart.jpg
Views:	1
Size:	41.3 KB
ID:	1162336

    Leave a comment:


  • scottsehlin
    replied
    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.

    Leave a comment:


  • randyohoh
    replied
    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.

    Leave a comment:


  • Naught1
    replied
    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.

    Leave a comment:


  • andykriech
    replied
    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.

    Leave a comment:


  • bkeane1259
    replied
    Re: Helium - a true micromonitor

    Originally posted by theLinks View Post
    No, :D
    ****er

    Leave a comment:


  • theLinks
    replied
    Re: Helium - a true micromonitor

    No, :D

    Leave a comment:


  • bkeane1259
    replied
    Re: Helium - a true micromonitor

    Originally posted by theLinks View Post
    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.

    Leave a comment:


  • theLinks
    replied
    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!

    Originally posted by bkeane1259 View Post
    Wait a minute......Um.....oh that wasn't me. I was pushing it in the dining room.

    Ok, there. I feel better now.

    Leave a comment:

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