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Author Topic: Stuffing my SP-2000 Speaker  (Read 3851 times)
AF6D
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« on: October 26, 2010, 08:42:10 PM »

Why? Speakers are supposed to have an air pocket behind them so that they move back and forth. Benefits?
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KD8DEY
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« Reply #1 on: October 27, 2010, 05:20:19 AM »

Changes the Bass response. Just don't go overboard Smiley
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W3LK
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« Reply #2 on: October 27, 2010, 10:49:35 AM »

Why? Speakers are supposed to have an air pocket behind them so that they move back and forth. Benefits?

The speaker cones will move whether there is an "air pocket" behind them or not. Otherwise, how do you explain sealed-back speakers in high-end stereo systems. Smiley
« Last Edit: October 27, 2010, 10:51:41 AM by Lon Kinley » Logged

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AF6D
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« Reply #3 on: October 27, 2010, 11:07:01 AM »

Why? Speakers are supposed to have an air pocket behind them so that they move back and forth. Benefits?

The speaker cones will move whether there is an "air pocket" behind them or not. Otherwise, how do you explain sealed-back speakers in high-end stereo systems. Smiley

Sealed back speakers are piezo type, or, there is a port. I'm a retired high-end sound and lighting guy Smiley For the cone to move without resistance there needs to be air flow.
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KG6YV
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« Reply #4 on: October 27, 2010, 01:33:56 PM »

First, I used to design speaker enclosures so I know a little, not everything. 
Second, I own an Sp2000 and have owned OEM speakers from Kenwood/Icom etc.

OEM speakers will sound OK if the manufacturer actually puts any money into the product.  Most do not.
They just size a box to match the transceiver and put in a $1.00 speaker (at volume prices). 
ICOM has about the worst speakers on the market, some from Kenwood and Yaesu are better.

The FT-2000 speaker (sp2000) isn't bad out of the box.  However, like most units there is no acoustic design done and no thought to damping resonances inherent to the driver or reflections inside the enclosure.  I once saw an ICOM speaker that had a 1/2 inch thick block of styrofoam behind the speaker (nice try ICOM).   DUMB!

Most OEM speakers are not sealed, there are air holes sometimes intentionally placed in the back panel.  That's OK.
The raw speakers they use do not require and are not designed for acoustic suspension (sealed box) applications.

About the easiest way to reliably improve a speaker cabinet/speaker combination(not always since some are just crappy) is to obtain some acoustic insulation.  This can be in the form of a wool insulation or very dense fiberglass.
Stuff the enclosure behind the speaker but don't pack it tightly. 

At most you will remove some resonances in the audio pass band and some white noise that is prevalent from cheaper
speakers and SSB audio from modern radios.  It might be worth it if you find that the stock speaker is anoying and the problem is white noise generated from the speaker itself.  I will also smooth the passband of the system.

FYI, the absolute best OEM speakers I own are the Sp2000 and the Tempo 2010 which came with my Henry Tempo
2020 transceiver.  I opened the Tempo speaker to install acoustic insulation and found that Uniden (the manufacturer)
had lined the entire case with 2 inch thick acoustic fiberglass.  Its a very smooth sound coming from a 4X6 inch speaker.
The SP2000 sounds great too, although that may be more a result of the FT-2000D which has the best audio I have heard in any HF transceiver on the market (heard em all including TenTec and Elecraft).  I put some wool insulation inside my SP2000 for kicks too.

Gud luck and have fun,

Greg


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W3LK
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« Reply #5 on: October 27, 2010, 06:19:35 PM »

Sealed back speakers are piezo type, or, there is a port. I'm a retired high-end sound and lighting guy Smiley For the cone to move without resistance there needs to be air flow.

It is true that most sealed-back speakers today are piezo, but I have both tweeters and mid-range cone speakers with sealed backs from the mid-70s. They were used to prevent interaction with large, long-throw woofers in base reflex designs.

That aside, stuffing a small speaker enclosure is really no different than putting batting inside large enclosures; it alters the frequency response.

Personally, it's not worth the effort for me as I use headphones unless there are visitors in the shack.

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AF6D
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« Reply #6 on: October 27, 2010, 09:08:01 PM »

Seems like more work than its worth. The SP-2000 is the first rig speaker I've ever purchased since I have favored bookshelf speakers and the like. You're right -- the SP-2000 isn't bad out of the box which is why I asked. I've read of others putting cottons balls and batting and that just tends to dampen the sound. The SP-2000 sounds fine.

Piezo tweeters don't generally have a baffle. Most mid-range speakers aren't piezo and will usually have a port. Subs are almost always ported because the speaker has to displace air.

Than you for the reply.
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AF6D
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« Reply #7 on: October 28, 2010, 12:08:50 PM »

Well, I stuffed it half way with material and didn't really notice an improvement. Imagine my surprise at how well assembled this damn speaker is!
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KG6YV
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« Reply #8 on: October 28, 2010, 05:48:29 PM »

Gee whiz, now I will just have to take my SP2000 apart too..... It does sound nice with the FT-2000, let us see what Yaesu did inside.

Greg
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