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Helium - a true micromonitor

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  • wogg
    replied
    Originally posted by Matt Clara View Post

    What happens if you use too fine a gauge? Asking for a friend...
    What Jeff said...

    Basically, too small a gauge is effectively adding a small resistor in series with your speakers. Heat wouldn't be a concern unless you're running crazy high wattage, but you could simulate the effect in Xsim if you want.

    Use an online wire resistance calculator like this one. Add the resistance as a series element before your crossover in Xsim. for example, a 50 foot run of 18 gauge is 0.3192 ohms each way, so add 0.638 ohms. That will affect frequency response a bit based on impedance, if you've got a 4 ohm speaker wherever it dips in impedance will have more loss in the wire than areas of high impedance. Larger gauge wire reduces that series resistance and that effect on the output.

    Let's say you have a 3 ohm minimum speaker with that 50 foot 18Ga run, you'll make a voltage divider with 3.638 ohms total and 3 ohms for the output = 82.4% of the signal makes it to the speaker. That calculates out to a 1.67dB drop at that frequency. Not huge, but adds up. Swap that 18Ga for 12Ga and your series resistance drops to 0.1588 ohms total. Now you've got 95% of the signal making it to the speaker and a 0.45dB loss.

    If you want to get really crazy, determine the capacitance and inductance of the wire as well and model that. Spoiler alert: the capacitance and inductance is almost negligible.

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  • Jeff F.
    replied
    Originally posted by Matt Clara View Post

    What happens if you use too fine a gauge? Asking for a friend...
    Heat, and before that maybe less bass response at mid to high listening levels.

    Leave a comment:


  • Matt Clara
    replied
    Originally posted by wogg View Post
    14ga is plenty large, 16 would be fine too.
    What happens if you use too fine a gauge? Asking for a friend...

    Leave a comment:


  • Dunk_c
    replied
    REL T Zero integrated with HMM in my work area using REW to set XO and volume, phase and position.
    Sub bass On carpet over concrete
    Graphs show best integration I could achieve when listening at desk (HMM toed in on desktop, sub under desk in corner) and when listening on a couch on opposite side of the room (HMM minimal toe in)

    Leave a comment:


  • MattyTeaks
    replied
    Have experimented with a few different iterations of the Heliums previously and loved them for their purpose.
    With some modifications on another project, I've got a couple pair of 91-8's looking for work.

    Considering giving a go at a Helium TMM design.
    Opening up some space with a mini tower setup 2.5 way.

    Worth the trouble?

    Leave a comment:


  • Dunk_c
    replied
    Thanks, just wasn’t sure about the current demand of low ohm speakers
    Last edited by Dunk_c; 12-04-2019, 03:32 PM.

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  • wogg
    replied
    14ga is plenty large, 16 would be fine too.

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  • Dunk_c
    replied
    I just replaced the fixed cables with binding posts on my speakers. Can someone recommend a speaker wire gauge? I need about a 2.5m run and I understand that the speaker impedance is low at about 5ohms IIRC.

    How about 14 awg?

    Thanks
    Last edited by Dunk_c; 12-03-2019, 04:05 AM. Reason: Update

    Leave a comment:


  • andykriech
    replied
    I have built the Lithiums and several of the Heliums. Love them both.
    I would build the Lithiums again if the size works for you. They are a very good sounding speaker and have good bass if fairly close to the wall.
    Andy.

    Leave a comment:


  • Goa604
    replied
    Thank you Scott! I will search for InDIYana 2017 and see if there is anything that would suit me better. Any recommendations on which build to look for? I would like it to sound very good, we are kinda tired of cheap bluetooth speakers. Thank you very much.

    Leave a comment:


  • scottsehlin
    replied
    The Helium could be made a little more bassy by moving to an MTM version (using the 8 ohm ND91, which can be tuned for a little more bass extension). Speakers like the Overnight Sensations or my Lithium project are about 4.5 liters and offer considerably more bass than the Heliums. In 2017 at InDIYana, there was a nanotech challenge that had a size limit of 3 liters. There were several designs that had impressive bass performance. If you search for InDIYana 2017, you can find some descriptions. I entered the Rhodium design, but it includes a Ribbon tweeter and is probably overkill for a "fun work speaker" from a cost perspective.

    Leave a comment:


  • Goa604
    replied
    I absolutely admire your knowledge and i understand the use case of monitors, however would a similar but more basy build be possible in not much bigger size? Im in search of a speaker build i would use for fun music at my workplace. We usually play trending music so a basy speaker wouldnt hurt. Any advice if this build could be modified or is there perhaps another build similar to this one i could find? I would limit the size to about 4 liters. Thank you very much in advance.

    Leave a comment:


  • Chris Roemer
    replied
    It doesn't work the way you think it does.
    Besides, when you use 2 speakers in parallel, their (combined) sensitivity rises +6dB (which is even WORSE, right?)!

    Leave a comment:


  • Scarface1
    replied
    Originally posted by scottsehlin View Post
    Re: Helium - a true micromonitor

    Sensitivity is pretty low, as Bryan mentions. They are right around 79 dB. I was targeting about the same power Bryan recommends - around 50W. The good thing about the Heliums is that they can comfortably handle that power.

    Hi Scott, I want to build this speaker for a 2.1 setup, but now I have use the nd65 because the subwoofer have a 80.7db SPL. I had to use 2 nd65-8 in parallel because of the missing Xmax.

    Now I read the heliums are at 79db, will this work with a sub (w5-1138) with 80.7db. I think so but just for sure to avoid mistakes.

    Leave a comment:


  • scottsehlin
    replied
    The 10W resistors will be fine. The 5's were nice when available to save a little space. Also, there are a couple of different tweeter resistor combinations that work (14 and 39 ohms or 15 and 47 ohms).

    Leave a comment:

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