Tweeters needed

hamerhead

hamerhead

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In my office at work I have a pretty craptacular stereo that includes some $2 garage sale Polk Audio Monitor 4a speakers. The tweeters were blown so I slapped in some that work but are 'meh'. Since I listen to them for 10 hours a day, a tweeter upgrade would be nice.

They look like these:

http://www.polksda.com/monitor4a.shtml

The cabinets are good and the 6.5-inch woofers work fine. The tweeter inset is 3.3 inches square.

Where might I find some original replacements (Ebay has a few used ones), or would something else be as good or better?

Thanks.

 
Well Mr Obvious......no I haven't, never even crossed my mind. But I will now!

As far as I can tell, these were made in 1984. I can't imagine after 30 years that they'd have anything, so I'm not really holding my breath. But it would be awesome to pick up some NOS units.

 
eBay1: Two available at $14.95 each.

ebay2: Three available at $19.95 each.

Probably more still-active auctions to pick from this list. Even though the listings may be a month old or more, they're BIN auctions and the vendor leaves 'em up until they sell.

 
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mathman said:
Check out

http://www.parts-express.com/?utm_source=google&utm_medium=cpc&utm_campaign=G+-+Brand+-+Main&utm_group=G-Brand-Main-Exact
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That's the first place I looked. I went down their entire selection of tweeters, but no visual matches. There were a few dome tweeters in square plates, but I don't know the measurements of the Polk plates, nor recommended crossover point, etc. The Polks are 4 ohm so keep that in mind if attempting to find a functional equivalent vs. a true drop-in replacement.

 
JB and Mathman - yep - scoured Parts Express and Ebay. PE didn't have exactly what I need, but there's a few things (ribbon tweeters) I'd like to try. /emoticons/default_cool.png And Ebay has a few of the actual Polk units, but I'm a little leery about ending up with what I've already got - blown up tweeters.

Joe - your link is bad, but I Googled Madisound. They have a ton of stuff. Very cool.

I emailed Polk. We'll see where that goes........

 
Here's a direct link to Madisound's soft dome tweeters.

To make things easier on yourself, measure the dimensions of the Polk tweeter's mounting plate. Also try to find the specs on the Polk tweeter. You want the replacement's sensitivity rating (in dB) to be as close to the original as possible.

 
Well I'll be dipped - I emailed Polk and got an almost instant reply - from a real person! He gave me the 800 number to their replacement parts department, so Friday I'll be giving them a call. That's pretty good customer service. I'm hopeful.

JB - the outside dimensions are 3.25 x 3.25. I'll snoop around Madisound's site in the morning, because they have a lot of stuff to wade through and I need sleep now. BTW - what's your take on ribbon tweeters?

 
hamerhead said:
BTW - what's your take on ribbon tweeters?
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Ribbon tweeters are awesome. They have more radiating surface and less weight per square inch than conventional tweeters. This imparts a treble that is both more detailed and yet smoother because they are free of the inertia and resonance artifacts of regular tweeters that let you know they're being driven hard.

Because of the larger radiating surface, a ribbon tweeter doesn't have the overshoot of a regular tweeter. They reverse directions more easily and in greater control of the electromagnetic field.

For example, this small folded ribbon tweeter (aka air motion transformer) presents a 1.26" x 1.6" rectangular area, but because it's folded, the total radiating surface is about 10 square inches. It would take 12 to 13 one-inch dia. dome tweeters to equal this radiating surface.

Several speaker companies use these folded ribbons, including ADAM Audio, MartinLogan's Motion series, and GoldenEar.

adam_a8x_1.jpg
mlmo35xt_blk_lpg34.jpg
aon%203%20and%20aon%202%20bookshelf%20speakers.jpg


I have auditioned several models of GoldenEar speakers and their treble is veru smooth, and yet detailed. Treble sounds very natural with no harshness or ringing when played loud.

I know less about the conventional ribbon, except that they are also very light and airy, and often more expensive than folded ribbons. Folded ribbons usually have a frequency response up to around 35-40Khz. The other kind of ribbon responds up to around 60Khz.

Although we can't hear that high, that ultrasonic bandwidth indicates how quickly a ribbon can start and stop--in other words, its rise time or how quickly it accelerates to make the sounds we can here. The difference in sound over a conventional tweeter is easily noticed.

 
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I have Ribbon tweeters in my Samson Studio Monitors. They are budget monitors but I really like their sound. The tweeters sound really clear and articulate. Highly recommended.

 
mathman said:
I have Ribbon tweeters in my Samson Studio Monitors. They are budget monitors but I really like their sound. The tweeters sound really clear and articulate. Highly recommended.
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This model, right? That's that folded ribbon.

cp_512_headline-Samson-Resolv-RXA6.jpg


 
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JohnnyB said:
mathman said:
I have Ribbon tweeters in my Samson Studio Monitors. They are budget monitors but I really like their sound. The tweeters sound really clear and articulate. Highly recommended.
Click to expand...
This model, right? That the folded ribbon.

cp_512_headline-Samson-Resolv-RXA6.jpg
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Actually I think those are the newer model. Mine are nearly 8 years old now, They are the Rubicon R5A

SAMSON_Rubicon_R5A_main.jpg


2-way Active Ribbon Studio Reference Monitor

2-inch Velocity Ribbon high frequency transducer

5-inch low frequency driver with Butyl Surround

Bi-Amp design / 50 watts low frequency / 25 watts high frequency

4-position high frequency level control

Tuned Shelf-Ported painted wood enclosure

 
^^^^

SAMSON_Rubicon_R5A_main.jpg


Very nice! A velocity ribbon and butyl surround woofer. That should hold up very nice. My Mirage M5si speakers still anchor my home theater surround system. They and their butyl surround woofers are 19 years old and show no sign of giving up. The folded ribbon design is pretty robust as ribbons go, too.

 
They sound great still. I only worry about the electronics. I had to replace the amplifier for the subwoofer.

 
Well I searched the world over and thought I'd found these to try:

http://www.parts-express.com/dayton-audio-b652-air-6-1-2-2-way-bookshelf-speaker-with-amt-tweeter-pair--300-651

The reviews are very good, and the size/price is perfect for how they'll be used. I thought about going higher end, but it's not the cleanest environment (neither sound nor dirt-wise), so that's a bit pointless. Plus it'll give me a chance at trying some ribbons on the cheap. Who knows - it may lead to bigger and better things.....

 
hamerhead said:
Well I searched the world over and thought I'd found these to try:

http://www.parts-express.com/dayton-audio-b652-air-6-1-2-2-way-bookshelf-speaker-with-amt-tweeter-pair--300-651

The reviews are very good, and the size/price is perfect for how they'll be used. I thought about going higher end, but it's not the cleanest environment (neither sound nor dirt-wise), so that's a bit pointless. Plus it'll give me a chance at trying some ribbons on the cheap. Who knows - it may lead to bigger and better things.....
Click to expand...
Good call! Those got a prety favorable review in Stereophile, a mag more accustomed to reviewing 4- and 5-figure components. They have a basic goodness about them. Stike got a pair of the standard dome tweeter version and is real pleased. The dome version is a Stereophile recommended component and they liked the ribbon version even better for being smoother and more linear.

 
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