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NOS 1 PI's [message #64063]

Mon, 20 September 2010 17:09

steve f
Messages: 238
Registered: May 2009

Master

Hi Wayne,

I found an new pair of Motorola piezoelectric tweeters gathering dust behind the rest of my "stored, I'll get around to using this stuff eventually" audio junk. I decided to build an old school pair of 1 PI's. I checked the archives, but I need a bit of help. I don't know the port size. I also believe you also added a coil in series on the woofer. Help please. I remember these were a great little speaker.

Steve

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Re: NOS 1 PI's [message #64064 is a reply to message #64063]

Mon, 20 September 2010 17:31

Wayne Parham
Messages: 18860
Registered: January 2001

Illuminati (33rd Degree)

I'll send plans.

The box is the same and the woofer circuit is the same. The tweeter hole cutout is a little different and the tweeter circuit is different. Just cut a hole to fit the tweeter in, basically the same size as the one in the current plans minus the "ears" for the hookup wires. The piezo tweeter is hooked straight across the input terminals and runs "wide open".

Later when you want to upgrade, just swap out the tweeters. Those old models with the piezos are near and dear to my heart, sounding very good for the money. At the time I designed them, there was no soft dome option with sensitivity anywhere close. But now that there is, you can get a much more refined sound. So when you can, spring for the upgrade tweeters.

"The winds of change have blown through"

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Re: NOS 1 PI's [message #64068 is a reply to message #64064]

Tue, 21 September 2010 17:45

steve f
Messages: 238
Registered: May 2009

Master

Thank you Wayne.

BTW has Vifa changed the tweeter? Supposedly a new surround for a bit more efficiency.

I'm going to hang the 1 PI's in my shop in the garage. I can't wait to junk the boom box I was using.

Steve

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Re: NOS 1 PI's [message #64069 is a reply to message #64068]

Tue, 21 September 2010 18:16

Wayne Parham
Messages: 18860
Registered: January 2001

Illuminati (33rd Degree)

One thing I always liked about the DX25 is the surround. It is wide enough to allow a relatively low cutoff.

Vifa has changed it slightly, part number DX25TG09-04 replacing the older DX25TG05-04. There are differences, but not enough to warrant a crossover change. I think there is more unit-to-unit variance than there is difference between old and new, so essentially I consider them to be the same.

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Re: NOS 1 PI's [message #64071 is a reply to message #64069]

Wed, 22 September 2010 09:44

steve f
Messages: 238
Registered: May 2009

Master

The 1 PI's are finished. And playing beautifully. I really like the controlled directional launch of the piezo's shallow horn flare.

I'm tempted to try a cheapo horn tweeter, Fostex ft17h or Audax pr125t1 or similar instead of the Vifa dome. The Fostex sounds good.

Nothing is arbitrary about Wayne's designs. I'm trying to gain a little knowledge without messing up too badly. Just wondering if this is a good idea.

Steve

PS: I'm cheating a bit. The coil for the woofer hasn't arrived, but I hooked them up to give 'em a try.

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Re: NOS 1 PI's [message #64079 is a reply to message #64071]

Wed, 22 September 2010 16:07

Wayne Parham
Messages: 18860
Registered: January 2001

Illuminati (33rd Degree)

I used a Fostex horn tweeter a long time ago and loved it. The only problem was it really needed a high crossover point with a steep slope or it would poof. That really limited my ability to use it in a two-way.

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Re: NOS 1 PI's [message #64353 is a reply to message #64079]

Sun, 17 October 2010 00:31

steve f
Messages: 238
Registered: May 2009

Master

My coils for the Alpha 8a finally showed up. These "little" 1 PI speakers are cranking out some fine sounds. Just for fun, after I corrected the crossover, I brought them into the living room and placed them in a system with a Morrison preamp and Transcendent Sound single ended OTL amp. My wife preferred them to a highly rated speaker & so did I. I'm leaving them in the system and can't wait to mess with the heads of a few audiophile friends.
Thanks again Wayne.

Steve

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