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  #1 (permalink)  
Old 06-02-2018, 3:13 PM
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Default Uniden BC15 and BC20 passive comm speakers

Ugh - not another subjective review of external speakers. Maybe this one is a little different hopefully.

I'll concentrate on the passive BC15 and BC20 and not compare it to every other combination known on earth. I've had many other systems over the years like manufacturer matching types with filtering to Fostex amps and equalizers. We won't go there or this thread would be miles long.

So far with the smaller BC15 - Right - Yes, it *is* a frequency-response limited, flat lifeless sounding speaker. That's what I want for cw / ssb hf monitoring. BUT not for swl or bcb listening, unless you like that type of flat lifeless sound.

Most of my monitoring career has been through either hi-fi or full-range speakers filtered down, rather than listening to the natural limited response of a transducer designed to limit the range in the first place. There is a distinct difference. This one is obviously less expensive, but by no means less effective.

CW - It is a natural match. If you don't have narrow filters, this won't cure that, but will make for far more pleasant listening and cut down on listener fatigue. And unless you plan on making the speaker bounce off the desk, the peak where the box resonates a little bit is quite pleasant. The thick plastic body of the speaker makes it sound less like a toy.

SSB - Lows are rolled off, highs are rolled off, and the midrange response seems flat and lifeless. Perfect! Again, if you are not used to this, it might take a few days or so to *really* evaluate the response to see if it plays with your brain properly. At first I was disappointed, being used to filtering full-range speakers down, but now my brain seems to be training itself. Long term listening fatigue is reduced.

tbc
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Old 06-02-2018, 3:58 PM
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i use a bc15 for my pro652...sounded muffled until i removed the grill and foam. now it sounds better. im thinking of getting the bc20 for the woodshop and my pro2096 .
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Old 06-02-2018, 4:16 PM
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Hi Lou9155! You beat me to it ....

FM - not so sure about this one. I actually LIKE a bit more fidelity on FM, be it broadcast or utility. Of course, this is where a real Motorola (not one rebuilt with a generic cone!) shines.

Scanners - may not provide enough output, although fine with the scanner that Lou9155 and I have. The Uniden connector is stereo plug to a mono speaker. Which means that in *some* scanner configurations, that are wired that way already, you may end up driving it with only half the output. Might want to have a stereo-to-mono adapter on hand just in case. And of course some handheld scanners have resistive attenuators inline to protect headphone listeners, further attenuating the output. Be sure to evaluate knowing this...

"Noise Filter". Up top is a noise filter button. I thought it was just some R/C/L filter to change the high frequency slope. Nope - it actually DROPS the impedance down to about 1.5 ohms, and of course lowers the power output handling cabability as a noise cancelling trick. I don't have that bad of an issue.

However, if you don't have a lot of hard-core noise to contend with, using the noise-filter under normal conditions actually provides a *slight* change in characteristics that may further take the edge off very high frequency noise. That slight change is much more useful than a sledgehammer approach just to make a point out of it.

tbc

Last edited by hertzian; 06-02-2018 at 4:36 PM..
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Old 06-02-2018, 4:33 PM
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IF-SHIFT change!

Even coming from the world of heavily filtering down full range speakers to my liking, I *always* tended to improperly use the IF-SHIFT control found on most receivers to fine-tune the audioslope, even when my other external speakers had filtering. It may seem small, but that limits my range when I do need the IF-shift to move away from another station!

But not so with the Uniden! I am dead-center in the IF passband, usually felt by the manufacturer's detent. This observation made me want to take a longer eval of the Uniden to see what's going on.

Tested on a Kenwood TS-590 - looked for any spectrum gotcha's by removing the antenna, and cranking the Kenwood's filters around from wide to narrow (no if-shift on the kenwood). No gotcha's to be found, other than hey, maybe I can listen to a wider bandwidth once in awhile without bleeding ears!

Over the years, I'm so used to 2.4k audio for ssb that I rarely even take it wider, even with more costly audio setups. But the Uniden seems different. No, I don't blow the Kenwood wide open, but when conditions allow, the Uniden does nicely at 2.8 - 3K and not much listener fatigue.

PROBLEM - well not so much. Ok, I've got the restricted flat response from the transducer cone itself, but of course there is not much of an enclosure, so I kind of lack a bit of depth. THIS is what larger speakers, even if metallic manufacturer speakers provide. Sure, I put stuffing into them (old clean beach towels, etc) to reduce the metallic boom.

This lack of depth is why I tend to use larger speakers with enclosures, or headphones because in a home setting, I don't like to listen to "point sources" of audio.

What about the slightly larger BC20? That's on the way. Primarily to see if I can coax a little more depth from what appears to be a nicely engineered comm-speaker.

At the end of the day: I'm one of "those guys" in regards to audio. Very sensitive. In the stereo realm, I can't stand horn-tweeters, no matter the cost, and truly prefer dome tweeters. I warned you.

Looking forward to testing the BC20 to see if it is just a louder version of the BC15, or will I get just a tad more depth. I'll let you know.

Basically, the Unidens are the real deal, and may not be everyone's cup of tea, just like shoes. I can say that they are NOT just some little piece of crap speaker thrown into a box and marketed as a comm-speaker that STILL has full range annoying responses.

Price vs Performance I think they are a great deal. But if you have never really listened to this type of speaker before, give it some time and don't go for a knee-jerk evaluation.

Last edited by hertzian; 06-02-2018 at 4:37 PM..
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Old 06-03-2018, 5:34 PM
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The larger BC20 arrives!

Within minutes, this is the one for me.

Despite having a lower frequency response down to 300hz, (vs 500hz for the BC15) the midrange clarity of a larger cone is immediately apparent.

What is really scary is that it sounds somewhat like my Yaesu SP-2000 manufacturer's speaker with the first high and low pass filters engaged which is what I normally use it at. Still, it lacks the overall depth with a limited enclosure, but is far improved over the BC15. Then again, it doesn't have the metallic depth sound of the Yaesu, even with the clean beach-towl stuffing.

It is close enough that unless I needed to do headphone filtering with the Yaesu, the BC20 is a total win all around.

BCB and SWL - now we are getting close to a real toss up! If you don't absolutely need highs and lows, the midrange clarity makes this something worth considering. No mistake - it still sounds "flat", but maybe dx'ers or those totally inundated with noise will appreciate it.

CW - unlike the smaller BC15, it is not as easy to make the enclosure ring. That may be good or bad depending on taste, casual ops, or running contests. Hard call here because it all depends.

In the end, unless your needs are specialized, such as very limited space, or maybe custom cw operations, the BC20, *for me* is the overall choice.

IF-SHIFT: I'm still in the center of the passband. Ie, the manufacturer's center detent on most rigs, provides the most pleasant balanced sound.

Alinco R8T / SR8T cw op note - despite being in the center of the passband, you may STILL want to move the IF shift just a *tad* off the center detent to make the signal on the opposite side of zero beat fall away real fast.

Nothing to see here: don't be tempted to remove the speaker grill. All you'll do is see the very thin dust cover material (not foam), and have a hard time finding the bite of the plastic screwthreads when you reassemble. Stripping the plastic is a real possibility here unless you are real careful. And of course any paperclip within reach will head for the dome without any cover.

Thumbs up on the BC20!
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Old 06-20-2018, 10:29 AM
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Here is another option. The Radio Shack, Optimus Pro-7 cat # 40-2066 has been known to the SWBC DX community for many years as "The Magic Speaker." They are rear-ported and thus easy to drive with low (~5W) and have superb voice reproduction. It uses a 4" LF driver and 1" dome tweeter. They are very stout, sporting a solid aluminum case.

JBL sound did a paper some years ago explaining why 4" drivers were the best choice for voice sound reinforcement. There is a model which uses a 5" LF driver. Don't waste your money, the Pro-7 with the 4" driver is the one to get. There was an older variant with the Realistic name on the front panel. Its the same and as good, only re-branded.

I must have collected 8 of them across the years and you'll find most SWBC DX'ers have one or two in their arsenal of hardware. I have one on my BDC536 and the audio reproduction is wonderful, full of detail and certainly not "flat" sounding ! These can be found on E-Bay more often than not; I just checked and here is a link to a pair:

https://tinyurl.com/y9kqw94f
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Last edited by WA4HHG; 06-20-2018 at 10:35 AM.. Reason: Added add'tl information.
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