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Old 10th November 2005, 08:54 PM   #11
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Default Re: I love my FE108EZ but.....

Quote:
Originally posted by Jaime
I think this is not a good idea.

The manufacturer in order to construct a driver full range, he necessary make many commitments.
Lows and high but not very linear.

You do not use the good things but you use the bad ones!!!!!!.

The FE108EZ does not need a tweeter and is very sweet. That is good. I would make only 2 way and the xver very low ( 100~150 Hz)

best regards Jaime
100-150Hz seems pretty like a pretty low crossover point for this driver. This of course depends on the loading, but this would certainly be too low for me in a sealed enclosure like we have been discussing. Midbass is not the 108's strong suite, not to mention it's lack of excursion to really reproduce 150Hz with any volume. Something like 300Hz seems more appropriate if we are still talking about sealed.
Joe
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Old 10th November 2005, 09:26 PM   #12
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The FE108eSigma is my single most favorite driver. In a well done horn is will reach 60-70 Hz and there is little need to have a tweeter.

But i have given much thot to using it as the heart of a mostly full range system. To get lots of dynamics & volume out of it and get it to mate with a woofer an XO of 250-300 seems about right to me (i might try to push it as low as 200 Hz to get it doing as much of the range as psossible. It would certainly work as a mid-tweeter, but the extended range of a ribbon is hard to touch... and if the ribbon isn't straining because it is XOed high so much the better. An XO here 0f 7-10k seems right to me (as a ref, Nelson says the Rushmore XO is 8.8k).

As always what you have to battle is integration. Pushing the XOs out on either end allows the FE108 to take over where it shines & gives it some help where it is its weakest.

Any XO is going to have to be completely transparent. probably best to integrate it into the amplifier (ie for hi-pass just shrink some of the coupling caps -- i would recommend a nice SE tube amp or a really good Class A differential tube amp (much harder to get rigt than an SE), a purpose built amp similar or the same with iron optimized for HF on the top too)

dave
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Old 10th November 2005, 11:07 PM   #13
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Default Aperiodic Enclosure

Scan-Speak sells this Aperiodic Encosure Vent. Is it a good start? Also, where can I learn more about these kinds of enclosures? I don't really know much about them.

http://www.partsexpress.com/pe/pshow...number=296-546

-A.F.
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Old 11th November 2005, 02:39 AM   #14
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Quote:
Originally posted by planet10
The FE108eSigma is my single most favorite driver. In a well done horn is will reach 60-70 Hz and there is little need to have a tweeter.

But i have given much thot to using it as the heart of a mostly full range system. To get lots of dynamics & volume out of it and get it to mate with a woofer an XO of 250-300 seems about right to me (i might try to push it as low as 200 Hz to get it doing as much of the range as psossible. It would certainly work as a mid-tweeter, but the extended range of a ribbon is hard to touch... and if the ribbon isn't straining because it is XOed high so much the better. An XO here 0f 7-10k seems right to me (as a ref, Nelson says the Rushmore XO is 8.8k).

As always what you have to battle is integration. Pushing the XOs out on either end allows the FE108 to take over where it shines & gives it some help where it is its weakest.

Any XO is going to have to be completely transparent. probably best to integrate it into the amplifier (ie for hi-pass just shrink some of the coupling caps -- i would recommend a nice SE tube amp or a really good Class A differential tube amp (much harder to get rigt than an SE), a purpose built amp similar or the same with iron optimized for HF on the top too)

dave
I'm definatly with you on this one. My 108's are in a two way right now crossed at 300Hz and are sounding quite good. I've been pondering recently switching to an active crossover though and getting myself some dipole bass for the low end. With the active crossover I could push the crossover lower with a steeper order crossover, and equalize the dipole bass if need be. I'm still educating myself on active crossovers, but it's definately in my to do list. I had not thought about adding a ribbon tweeter as I've never been dissatisfied with the upper range on the 108's. I've also never spent much time with a ribbon tweeter. Ignorance is bliss I guess.
Joe
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Old 11th November 2005, 02:59 AM   #15
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Quote:
Originally posted by Josephjcole
I've also never spent much time with a ribbon tweeter. Ignorance is bliss I guess
I was spoiled forever by the Decca London Ribbons in the late 70s.

dave
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Old 11th November 2005, 10:58 AM   #16
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Dave slightly OT, but... do you know what happened to John Pomann?
http://www.snippets.org/filters/crossover.htm#ordering
I found the link off of your page and it looks perfect for someone like me. Unfortunatly he doesn't seem to be around any more. At least he doesn't answer e-mails. I would be happy even with a copy of the manual if he is no longer in the selling these kits. Any insights into this?
Thanks
Joe
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Old 11th November 2005, 11:20 AM   #17
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Quote:
Originally posted by Josephjcole
do you know what happened to John Pomann?
[url]http://www.snippets.org/filters/crossover.htm#
I haven't talked with him for a long time. I did expect him to drop off the map. He was a med student and i thot he'd have problems keeping it up when he became an intern.

I have bits & pieces of his website on my drive, i should have at least an early version of the manual but on a quick look couldn't find it.

dave
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Old 11th November 2005, 04:57 PM   #18
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Yeah, the project looked like it would be something that would wear somebody out. Not much room for anykind of profits for him. Hard to keep a hobby/buisness like that going on goodwill alone. Especially if you are a med student... that sounds pretty exhausting. If you find any of the manual or anything else that might be helpfull in designing an active crossover I'ld love to see it.
Thanks
Joe
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Old 15th November 2005, 05:04 AM   #19
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Default Still Designing

I have made a fomacore mock-up of the speaker design and I think i like it. I was able to catch some errors in design and measurement, so I am really glad I made a small model first.

Has anyone else used balsawood or something similar to simulate a scale model? My next project is to make a small-scale balsa model to see how I like the look of the speakers. I think I want to also try veneering it to see how it works out astheticly.

Also, Would anyone see any issues in using the Scan-Speak 18W/8531G Revelator as the main driver for the MLTL. i have modeled it with Mr. Kings worksheets and I am happy with the results.

Driver/Opening Ratio: 4:1
Line Length: 77"
Lb/sq foot: .6 (Wool)
Offset Ratio: .46

The main enclosure will be 15" deep and 11" wide, 42" high.

I am currently thinking about using 1" Marine-Grade Mohagany Plywood. To get really wild, I also want to experiment with using 1" Sitka Spruce to form the soundboard inside the MLTL. If it doesn't work, I would remove it, but the sound possibilities really intrigue me...
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