Best sounding external speaker is the one you make yourself.

Discussion in 'Microphones, Speakers & Audio Processing' started by KC8VWM, Jun 12, 2019.

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  1. KC8VWM

    KC8VWM Ham Member QRZ Page

    Some of us might remember those days of listening to the BBC news on a floor console shortwave radio set. The sound was Hi-Fi quality and filled the room with the booming, warm authoritative tones of the radio announcer reporting the daily news from London, as you relaxed in your big easy chair...

    zenith.jpg

    What if I told you you can bring back that same full bodied sound quality to your radio again, even if it's a modern solid state rig by constructing this economical external speaker for your shack?

    This project speaker for your station simply rivals any manufacturer supplied external speaker made for your rig hands down. Metal or plastic speaker enclosures, or using lesser quality plastic computer speakers, or other smaller bookshelf type speakers in the shack are simply no substitute and just will not do !

    When it comes to external speakers, there's no substitute for what you hear from a big wooden speaker enclosure and a much bigger speaker.

    Yes that's right, bigger is indeed better! In fact, speaker size itself is what makes all the difference in what, and how you hear something on your radio. Why? Because even the very weak stations you strained and struggled to hear in the past on smaller external speakers, now sound like they are right there in front and center on a bigger speaker. You can now hear more information in the audio making it much more legible to understand than before, so there's simply no more straining to hear anyone in the distance anymore.

    This project is a 12" external speaker setup for your station. I start by choosing a vented wooden speaker enclosure as typically found at any local stereo install shop or outdoor flea market car stereo vendor in your local vicinity.

    Typically the speaker enclosure is around $20 or so, cash and carry. (no shipping costs. )

    [​IMG]

    Purchase a high quality, powder coated steel mesh speaker grill for around $5 - $6 as supplied by same stereo install shop / fleamarket vendor. I would avoid plastic versions as they can crack, although it will be cheaper to purchase though.

    [​IMG]

    Find an old full range (not bass reflex) paper speaker to install inside. These are available on Ebay, fleamarkets, guitar amplifier parts places, salvage from old ceiling mounted PA speaker, ( other suggestions? etc.) The speaker doesn't in any way need to to be capable of handling high power. Less is better so 10 to 20 watt rating is just about perfect and will do. I found one of these speakers at a local flea market vendor in my area for only $10.

    speaker.jpg

    Next, install the paper speaker inside the wooden enclosure, wire it all up, install the steel grill on the front to protect the speaker, plug it into your rig and your new station speaker will look and sound like no other

    Here's an actual demo of what you will hear...



    Choosing the right external speaker for your station makes it very easy and enjoyable to listen to for hours, without experiencing listening fatigue and it's like HD audio for your ears. You simply can't buy a more fully capable, external speaker for your station that sounds any better than one you can easily make yourself. :)
     
    Last edited: Jun 12, 2019
    K0UO, AC8UN, NL7W and 1 other person like this.
  2. G0GSR

    G0GSR Ham Member QRZ Page

    Sounds very resonant to me... But if you like it.... :)

    There's a lot to loudspeaker design. Have you plotted the response of that driver/box combination?

    A 12" speaker is going to be very directional at the tone frequencies used for CW.
    Frank
     
    WA7PRC likes this.
  3. K6BSU

    K6BSU Ham Member QRZ Page

    You are correct. Bigger IS better! Klipsch horn 002.jpg
     
    KC8VWM likes this.
  4. K4EM

    K4EM XML Subscriber QRZ Page

    Or go to Goodwill or yard sale and buy a Pioneer, Klipsch, Yamaha, Sony, KLH; TV center speaker for $6. They sound great.

    Dave
     
  5. KD4ZMV

    KD4ZMV Ham Member QRZ Page

    Is that an A7?
     
  6. KD4ZMV

    KD4ZMV Ham Member QRZ Page

    OOps, I replied to the wrong post, I'll try again.
    Is that an A7?
     
  7. W8AAZ

    W8AAZ Ham Member QRZ Page

    Must have a big shack!
     
  8. WB2GCR

    WB2GCR Ham Member QRZ Page

    No, that is a corner enclosure with what looks like an 811 cast horn on top...

    As far as KC8VWM's project, while it is a nice idea, unfortunately, it's not quite that simple.

    IF one wanted that "old" sound, best to buy one of those old console radios, borrow the
    output stage (or another amp) and use the old speaker in the original radio enclosure.

    Fwiw, drivers (aka speakers, as opposed to speakers being box + driver(s)) are not
    "bass reflex". Cabinets are "bass reflex" or "ported". The enclosure shown is a bass
    reflex enclosure/ported/vented.

    Those old console radios were NOT "bass reflex" or even "sealed", they were open back.
    The open back requires that the driver have a high "Q" to produce bass, and a relatively
    low Fs (resonant frequency).

    High Q drivers usually do not want to be in a "vented" enclosure, they want a large volume sealed enclosure.

    In any cabinet with a "port" or "reflex" opening, the volume of the enclosure and the
    VAS parameter of the driver need to be "matched". What this means is that the system,
    box + driver + port = a filter response. The standard responses are Butterworth, Bessel,
    and C4. Of course, it's not essential for this application to be dead bang on one or any
    of these ideal response curves.

    In addition, the other T/S parameters, need to be included in the design. They are
    Fs, Q, VAS. What happens if these parameters are randomly chosen for a given box
    volume is that you get a rather undesirable result in terms of the lower octaves of the
    response. This includes truncated LF response, with a big peak before rolloff, or little
    or no bass response. You could just get lucky. It does happen.

    If this seems too picky, or technical, ask yourself if you would design a PI network for
    a rig by grabbing "good looking" parts at a hamfest and wiring them up to look about
    right? Or making any other sort of RF filter, would you do that by guessing? Think not.

    The good news is that measuring the T/S parameters of a driver is fairly simple, and you need
    only a resistor, scope and signal generator (and an amp to drive the speaker). That and
    some simple formulas. Then you can find many online "bass box calculators" and you
    will get pretty close to the resulting curve for a given box, plus you can trim the port
    volume and length for best results.

    If for some reason one did not want to do an actual design, my suggestion is to use the
    largest volume enclosure possible, the smallest diameter driver (as in if you had a given
    box, and could fit a 12" or a 15", if they were apparently similar (as in old paper cone drivers
    from a 1960s stereo/TV console) use the smaller diameter. BUT do as much as possible
    to absorb the sound inside the cabinet. Polyester fiberfill (pillow stuffing) and a layer of
    thick felt on the interior walls will make the midrange and highs sound as good as they
    are going to. Empty cabinets are NG. Too much reflection.

    The larger drivers will work fine for ham use, and the concern about directionality does
    not exist for this application at all.

    I agree that one can DIY excellent sounding speakers for ham use.

    _-_-bear
     
    N0TZU and WA7PRC like this.
  9. WA7PRC

    WA7PRC Ham Member QRZ Page

    For voice communication work, in a room w/ lots of reflections and driven by a ham rig w/ narrow response, it's not as important as in (for example) a professional/musical application. In fact, some communication speakers feature filter(s) to shape the response. :)
     
  10. WB2GCR

    WB2GCR Ham Member QRZ Page

    What is "not as important"??

    Shaping the response would not be as the result of the enclosure.
     

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