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Deans new crossovers


jannegard1

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These are Craig's, which are very similar to Jan's. Jan has a very nice set of Universals which I built him about a year ago, but he much prefers the Jupiter build. This is pretty much where I'm at too, the Jupiters are just killer

 

 

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Edited by DeanG
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These are Craig's, which are very similar to Jan's. Jan has a very nice set of Universals which I built him about a year ago, but he much prefers the Jupiter build. This is pretty much where I'm at too, the Jupiters are just killer.attachicon.gifimage.jpg

 

I've a question for you, Dean.  Those XO's are super clean looking but in nearly every XO I have ever seen, there are always resistors, and I notice your Jupiter build has none.  Other than "they don't need them" can you explain why?

 

Also, in one component (autotransformer?) a wire is a soldered on the left, but is connected by a crimped on blue connector on the right.  Why is that, or what is the thinking on that?

Edited by wvu80
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What type of screw is in the center of that little orange coil?  Brass?

 

It doesn't look brass, but sometimes the photos are not accurate.  That screw looks like all the other wood screws holding components.

+++

 

Related:  What is the material in the CENTER of that orange coil?  It almost looks like silicon seal or hot melt glue that has set up, but I wonder what its purpose is?

Edited by wvu80
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I'll take a shot  :)

 

The autoformer input is usually 0 - 5.  This would equate to C -  -0 on this one.  With this one, one can move the non-common input to decrease the attenuation by 1 or 2 dB.  I assume both connections on the output side of the autoformer are moveable, to adjust the mid attenuation to taste.

 

That looks like a plastic spool for the inductor, or just a plastic cap to hold it down with a brass screw.  A steel screw would disrupt the 

magnetic field inside the coil.

 

The tweeter is probably needs no attenuation, therefore no need for l-pad resistors. 

 

But hey...I'm still learning!

 

Mike

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It's been shown that metal in the center of a coil changes the inductance.  That's why a brass screw is typically used.  It will not change the inductance.  Pretty well known.

 

However, as fast I as say this.............I am betting Dean has a reason for what we are seeing if it's some other metal, or even plastic.  :)

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Nice job guys.

 

All of the screws are non-magnetic stainless steel. I fill small coils with hot melt, lift the coil a little and let the glue run underneath a bit. I then press down, and fill the hole. After it cools, I drive a screw in.

 

People who like to play with different tweeters usually have a pair of Al's attenuators, so I leave it up to the customer to dial in the tweets. I do try to steer people away from the adjustable l-pad version, which I don't like. If someone doesn't want the add on attenuators, I can solder in a l-pad using high quality resistors -- normally Mills, unless they specify something different.

 

Mike pretty much nailed the deal with the jumpers. The first set went to Craig, and they were a prototype of sorts. Jan's order was in, but I needed to validate some things before I started his build -- and one of those things was the attenuation level for the BMS midrange. I scaled the parts based on 12dB of attenuation, and I was pretty confident with that number. However, Craig called within a day after receiving them to tell me that he thought the midrange was too forward. We were prepared for that possibility, and I had them set up so the midrange connections on the 3670 could be moved to add 3dB of attenuation. This would of course require the addition of a 15 ohm resistor in parallel with the driver to keep the crossover from shifting. Craig and Jan are both at 15dB of attenuation. Right now, I'm debating on whether I should rescale the parts and fix the attenuation level, or just go ahead and leave as is -- offering the two choices and taping a resistor to the board.

 

I'm expecting to be told by Dennis and John (Warren) both to go ahead and actually solder the resistor in and lock it in at -15dB. I asked John to do some measurements for me after sending him a pair of the 3670s, and the results were interesting. After years of battling the idea of l-pads and running resistors in conjunction with autotransformers -- several of the plots showed a clear improvement by using the resistor in parallel with the driver. The plots confirmed what Dennis and Al had both been saying for years. I will leave it to John to post and explain the results of the plots (if he wants). Resistor or not, I would prefer that the attenuation level be "fixed". My preference would be no resistor, and that's based on the wide range of things I've tried over here with my LaScalas. The effect of the resistor may look better on paper, but it just sounds better to me without it.

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