Advice on adding a tweeter to Pioneer B20 8" FR

[LowVoltage]

Advice on adding a tweeter to Pioneer B20 8" FR

I've just finished building .67 cu ft. vented (BR) cabs for these drivers. I've let 'em burn in for two weeks now. And I'm generally pleased with the end results. However, "beaming" does seem to be a problem (typical of some full ranger's). I've tried A rear firing piezo, that with L-pad added is still overly bright... to me.

The Pioneer's do have a nice bottom end and good mid range. I would think that I would be able to cross them over a little higher if necessary. I'm looking for a tweeter that has a nice silky, smooth top end and a price in keeping with the $20 or so purchase price of the Pioneers. I've included a link to the speaker spec sheet

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=290-045

A. Recommendation for a tweeter

B. Recommendation for the attendant XO. (I can build what ever I need) and lastly:

I want to include an L-pad on this tweeter as well. Where do I insert that in the XO design....before or after the XO. My current L-Pads are 8 ohms. If I wind up with a tweeter thats rated at 6 ohms, would I be able to use the *ohm pads?

Thanks in advance for any help

Mike

 

[sreten]

Hi,

This ?

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=270-102

or This ?

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=270-049

The L-pad goes between the tweeter and c/o capacitor.

For a simple first order c/o on the tweeter only 1uF = 20KHz, and you
scale from there, e.g. 10KHz = 2uF, 2.7uF = 7.5KHz, and 3.3uF = 6KHz.

I'd say 3.3uF is the lowest frequency you should use.

/sreten.

 

[LowVoltage]

Thanks sreten:

Instead of a simple 1st. order X/O on the tweeter only, I think I will go with a 2nd order on both, what will now be a woofer, and the tweeter. I can cross them over a little higher. I was thinking 4000 to 5000 Hz. This would retain the character of the Pioneers and give me a little relief in the top end, I was thinking along the lines of a fabric dome tweeter, such as Hi-Vi K1 or the Audax TU025F1.

I know the issue of a 4/6 ohm tweeter could probably addressed with fixed padding resistors on the tweeter, but.......i would still like to be able to control the output level the tweeter. And I don't know how to design an X/O network like that. I guess if I stick to 8 ohm tweets that would eliminate THAT problem.

Mike

 

[sreten]

Hi,

By adding a 2 ohm series resistor to a 6 ohm tweeter you can use
the L-pads ideally, though they'd still work quite well with 6ohm.

Going for a proper 2-way you really shouldn't use a twin cone driver.

Also you should read up on baffle step compensation.
Using this you can effectively boost the treble of a twin cone driver.

http://www.quarter-wave.com/General/BSC_Sizing.pdf
http://www.quarter-wave.com/General/BSC_Variable.pdf

For lots of info on tweeters see here :

http://www.zaphaudio.com/tweetermishmash/

/sreten.