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Open Baffle Epiphany!

i definitely recommend the miniDSP. if you get the microphone you can use the REW software to feed equalization fixes to your miniDSP. took me a bit to figure it out (and you need an external power supply...) but it was a great way to set the crossover point.

martin king recommends against running both drivers full range. says you get a mound where the 2 drivers cross.
 
rogerfederer said:
i definitely recommend the miniDSP. if you get the microphone you can use the REW software to feed equalization fixes to your miniDSP. took me a bit to figure it out (and you need an external power supply...) but it was a great way to set the crossover point.

martin king recommends against running both drivers full range. says you get a mound where the 2 drivers cross.
Click to expand...

Because of all the problems I've had with my active crossover and amplifiers I have tried running both my FR drivers and Alphas without a crossover or filter. Now call me crazy or deaf or a little of both but in my system I like the way this sounds. I'm currently using a filter while I figure out what to do with my crossover but when all is said and done I'm not sure what my final solution will be.

cubdog
 
Running the AN's and Alpha's without a crossover or filter is akin to listening to two different sounding full range drivers at the same time.

The Alphas will play pretty high and some folks use them as FR speakers rather than as woofers but used that way they'll compete with but lack the HF or midrange of the AN's.

And it's better to augment the AN's with what the Alphas do best rather than compete with them.
 
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Jim Shearer said:
I don't know how you can get proper integration of the drivers w/o the XO. Not to mention the very real possibility of over excursion on the FE126en.

Please check out Martin King's excellent site:
http://www.quarter-wave.com/OBs/OB_Theory.html
http://www.quarter-wave.com/Project09/Project09.html

I built a modified version of his small passive OB using Fostex FF85k & Eminence Alpha 15a with great results.

Cheers, Jim
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Hadn't thought about over-excursion. Active crossover it is then.

Thanks for the links, I've read the papers, understanding some of what Martin King says, hopefully the parts that matter. I'll go with the Alphas in the H-frame. Is it correct that the internal dimensions of the frame should be 16" x 16" x 16" with the board holding the Alphas centered equidistant front and back?
 
rogerfederer said:
i definitely recommend the miniDSP. if you get the microphone you can use the REW software to feed equalization fixes to your miniDSP. took me a bit to figure it out (and you need an external power supply...) but it was a great way to set the crossover point.

martin king recommends against running both drivers full range. says you get a mound where the 2 drivers cross.
Click to expand...

Yeah I can see now why not using a crossover wasn't the greatest idea.

From what I've read so far the miniDSP with the microphone and REW looks good, but I'm just starting out on xo, I really know next to nothing about this. Since this is computer-driven, I wonder if there is a sound card and software that can be used in the same way? I'm already using a computer with a sound card up-sampling to FLAC files and running those as a source.
 
Poultrygeist said:
Running the AN's and Alpha's without a crossover or filter is akin to listening to two different sounding full range drivers at the same time.

The Alphas will play pretty high and some folks use them as FR speakers rather than as woofers but used that way they'll compete with but lack the HF or midrange of the AN's.

And it's better to augment the AN's with what the Alphas do best rather than compete with them.
Click to expand...

I'm probably missing the obvious but what are AN's? All I can think of is Alnico Nickle or Audio Note.:scratch2:

Is there anything you'd suggest I look at for active crossovers for the FE126En and the Alpha 15"?
 
1.6Baffle said:
I'm probably missing the obvious but what are AN's? All I can think of is Alnico Nickle or Audio Note.:scratch2:

Is there anything you'd suggest I look at for active crossovers for the FE126En and the Alpha 15"?
Click to expand...

He's referring to my full range Audio Nirvana speakers.

cubdog
 
I am planning on using a Yung SD-200 plate amp for the Alphas. What type of filter or crossover would I need for my Fostex 126 speakers. I'm not planning on using an active crossover. What options would I have?
 
1.6Baffle said:
I'm probably missing the obvious but what are AN's? All I can think of is Alnico Nickle or Audio Note.:scratch2:

Is there anything you'd suggest I look at for active crossovers for the FE126En and the Alpha 15"?
Click to expand...

Analog 2 way electronic crossovers ( Parts Express prices )

Behringer CX2310 - $79

dbx 223 - $159

Ashly XR-1001 - $250
 
Bonkers60 said:
I am planning on using a Yung SD-200 plate amp for the Alphas. What type of filter or crossover would I need for my Fostex 126 speakers. I'm not planning on using an active crossover. What options would I have?
Click to expand...

I'd try the 126 running full range off the amp with nothing in the signal path and then use the Yung plate amp's internal crossover on the Alpha's. If you don't like the sound you've lost nothing by trying.

I enjoyed this combination for a good while and finally bought an active crossover. I know it's not what MJK recommends but it sounds very good to me.
 
I wouldn't worry about over excursion of the FE126.

It's one of the toughest FR drivers around. Watched deliberate efforts to destroy a pair at Hornfest one year but it never happened.
 
Poultrygeist said:
I'd try the 126 running full range off the amp with nothing in the signal path and then use the Yung plate amp's internal crossover on the Alpha's. If you don't like the sound you've lost nothing by trying.

I enjoyed this combination for a good while and finally bought an active crossover. I know it's not what MJK recommends but it sounds very good to me.
Click to expand...

Thanks, I think that this is what I will go with. I am trying to keep my startup costs to a minimum, and I can always try something different in the future.
 
Poultrygeist said:
I wouldn't worry about over excursion of the FE126.

It's one of the toughest FR drivers around. Watched deliberate efforts to destroy a pair at Hornfest one year but it never happened.
Click to expand...

Good to hear that the FE126's are tough, I'll relax about running them as they are for now without crossover or filters. That you ran them like that for a while gave me an idea, since I'd prefer the simplest path from the source to the Zen Amp to the FE126s would I lose anything by just putting a 150Hz FMOD low pass filter in the line to the Alphas and leaving the FE126's as is? Or is an active crossover noticeably better?
 
I might have made a mistake by centering the FE126En's in 20" x 32" baffles. Should I make new baffles to offset the drivers? What would be good dimensions for the baffles for that driver?
 
Check out the edge baffle modeling software; helps you see what different driver placements do to your sound curve
 
rogerfederer said:
Check out the edge baffle modeling software; helps you see what different driver placements do to your sound curve
Click to expand...

Thanks for suggesting Edge, interesting to see the effects of changes in action. It does look like centering the driver gives a big hump at 400 Hz. Back to the workshop. Is it a good graph for a 4" driver in an open baffle to have the line rise at a low Hz (around 200 Hz) to about 8 dB and then go across to the higher Hz close to the same level?
 
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1.6Baffle said:
Good to hear that the FE126's are tough, I'll relax about running them as they are for now without crossover or filters. That you ran them like that for a while gave me an idea, since I'd prefer the simplest path from the source to the Zen Amp to the FE126s would I lose anything by just putting a 150Hz FMOD low pass filter in the line to the Alphas and leaving the FE126's as is? Or is an active crossover noticeably better?
Click to expand...

The low pass filters ( not FMOD's ) I used with the Alphas were 80Hz.

As you would expect an active offers superior LF/HF integration. The difference in my case while better was not earth shattering.

Running the full rangers straight off the amp and using a plate amp with it's built in active crossover to filter the Alphas sounded better than using the low pass filters with a standard amp.
 
Poultrygeist said:
The low pass filters ( not FMOD's ) I used with the Alphas were 80Hz.

As you would expect an active offers superior LF/HF integration. The difference in my case while better was not earth shattering.

Running the full rangers straight off the amp and using a plate amp with it's built in active crossover to filter the Alphas sounded better than using the low pass filters with a standard amp.
Click to expand...

Thank you, that helps a lot, I'm slowly getting there.
 
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