Jak sie masz bracie?!
Yes, I've removed the dustcaps off my FE206E drivers and installed paper piezo tweeters...then phase plugs. I have some pictures laying around on my hard drive, somewhere.
Anyway...it's very easy, I took a hobby knife (x-acto, scalpel or whatever will do) and gently scored around the dome a few times till I got through. It's pretty intimidating at first (I didn't want to F it up) but trust me, it's easy. Also, it's well worth the effort, although I my paper piezo experiment gave mediocre results so far, the phase plugs are a big improvement. I didn't try a socket like the 'decware' mod, I made my own wooden plugs.
What are you planning to do?
Yes, I've removed the dustcaps off my FE206E drivers and installed paper piezo tweeters...then phase plugs. I have some pictures laying around on my hard drive, somewhere.
Anyway...it's very easy, I took a hobby knife (x-acto, scalpel or whatever will do) and gently scored around the dome a few times till I got through. It's pretty intimidating at first (I didn't want to F it up) but trust me, it's easy. Also, it's well worth the effort, although I my paper piezo experiment gave mediocre results so far, the phase plugs are a big improvement. I didn't try a socket like the 'decware' mod, I made my own wooden plugs.
What are you planning to do?
Witam,
Many thanks for the answer.I've done that many times before ,but never on Fostex.I'm using FE 206E and I was considering to do it but first wanted to ask what are the results. Some drivers benefit from doing it and some not.
I'm not using tweeter ,but I have a lot highs due to notch filter I'm using with this driver.I'm using it in BS enclosure and I dropped about 5-6 db to get satysfying higs and lows.
Some drivers I had sounded best without and phase plug ,much better than with it and I tried a couple of shapes I made of wood.
All Best
Bartek
Many thanks for the answer.I've done that many times before ,but never on Fostex.I'm using FE 206E and I was considering to do it but first wanted to ask what are the results. Some drivers benefit from doing it and some not.
I'm not using tweeter ,but I have a lot highs due to notch filter I'm using with this driver.I'm using it in BS enclosure and I dropped about 5-6 db to get satysfying higs and lows.
Some drivers I had sounded best without and phase plug ,much better than with it and I tried a couple of shapes I made of wood.
All Best
Bartek
With my first phase plug attempts on this driver I was getting some sibilance, which bugged me a bit, but the highs were more extended and I noticed better response off axis so I kept experimenting. My final result was a plug diameter that left a <1mm gap between voice coil and plug. I also gently sanded the cut edge with 400 grit paper to smooth it as much as possible, that took care of the sibilance entirely. The final plug extends just past the wizzer and has a bullet shape that compliments whizzer's profile. Sounds fantastic.
Powodzenia!
Powodzenia!
Hi,
New to this forum! I am looking to buy piezo tweeter that you find under a fostex speaker. They basically have a piezo element with some sort of a high density foam or paper on top of it and I have heard some of them sound great.
I am looking to buy this wide-range Piezo tweeer, but without any luck. Does anyone know where to buy them?
Or if I buy regular piezo horns and remove all the plastic, is the piezo element at the core of all the casing the same as what I am looking for? Has anyone tried this?
Any comment and suggestion will be much appreciated!!
New to this forum! I am looking to buy piezo tweeter that you find under a fostex speaker. They basically have a piezo element with some sort of a high density foam or paper on top of it and I have heard some of them sound great.
I am looking to buy this wide-range Piezo tweeer, but without any luck. Does anyone know where to buy them?
Or if I buy regular piezo horns and remove all the plastic, is the piezo element at the core of all the casing the same as what I am looking for? Has anyone tried this?
Any comment and suggestion will be much appreciated!!
Hey, check this out, it may be what you're looking for. What a coincidence!
http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&rd=1&item=5746294373&ssPageName=STRK:MESE:IT
These have the perfect diameter to fit in a fostex Fe206 driver.
http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&rd=1&item=5746294373&ssPageName=STRK:MESE:IT
These have the perfect diameter to fit in a fostex Fe206 driver.
tmblack said:
That would be me... the phase plug actually attaches to the pole piece and doesn't touch the cone. Removing the dustcap thou does reduce the mass, increasing sensitivity & increasing Fs -- i'm usually adding cone treatment which tends to bring both back to where they were before the dustcap-ectomy.
The theory behind the phase plugs is 2-fold.
1/ removing the dustcap & filling the hole inside the voice coil eliminates the oil-can resonance that lives in the voice coil cavity.
2/ the reduction of the distance across the cone by a but better than a factor of 2 improves the HF dispersion characteristics.
3/ very dependent on the geometry, but there can also be HF reflection off the phase plug.
On the downside the dustcap can be used by the manufacturer to supress a resonance, which will be let free when it is removed, but as Mark M shows with his TB881 mod, getting the dustcap installed in exactly the right place can cause unit to unit variation making this resonance control sometimes spotty.
Listening tests tend to confirm the theory... measurements will be forthcoming sometime after my mic pre is up & running.
With Bart's 206/207 numbers phase plugs for those are in the works.
dave
Of interest to this thread could be this series of pictures on a radio Shack 40-1354...
http://p10hifi.net/tlinespeakers/FAL/1354-surgery/1354-surgery.html
dave
http://p10hifi.net/tlinespeakers/FAL/1354-surgery/1354-surgery.html
dave
Banned
Joined 2002
Halo back again.
I have to report that I removed the dust cups from my Fostex FE 204 (older brother of 206E) and I must say it sucks.
It sounds worst then with the dust cups in place. I don't know why, maybe it has something to do with the round hole with net in it. The drivers started to scream and the highs got much worst.
As I already destroyed the drivers I also painted them with dammar and this is a great improvement.
I also made some phase plugs, but haven't tried them yet.
Will report about them later.
Maybe with some phase plugs things get back, and maybe they will get better than with dust cups.
Bartek
I have to report that I removed the dust cups from my Fostex FE 204 (older brother of 206E) and I must say it sucks.
It sounds worst then with the dust cups in place. I don't know why, maybe it has something to do with the round hole with net in it. The drivers started to scream and the highs got much worst.
As I already destroyed the drivers I also painted them with dammar and this is a great improvement.
I also made some phase plugs, but haven't tried them yet.
Will report about them later.
Maybe with some phase plugs things get back, and maybe they will get better than with dust cups.
Bartek
Attachments
Halo again,
I did some more listening. As somebody said before, here in this thread without dust cup they somehow shout.
So now I painted them with one layer of dammar and put those phase plugs from the picture in.
They sound very smooooth and clean now, but somehow not open. The bass i diffrent quite nice, maybe becouse of cone treatment. I don't know it's just completely diffrent driver and I must say I don't quite like it ,now except it is cleaner and more relaxed sounding. The highs are still missing,a lot of them are missing.
At this poin I must say how do I use this driver. It works in 60 litre bass reflex enclosure with rectangular port. I'm using pass band filter that is 4mH coil, 10R mills resistor and 2uF Siemens MKV cap in paralell and in series with speaker.
I was very satisfied with the highs of Fostex with this circuit, it was 95% as a good tweeter, almost nothing missing.But now it is some 60%. Highs are rolled off.
I'm thinking what may couse it. Maybe the gap between phase plug an the cone is too big. It is about 1,5-2mm around. Maybe I will shorten the plug to make it thicker, it has exponetial shape.
Or maybe the shape should be strait , not exponential?
>Illusus
Can you post the pictures of your phase plugs?
Bartek
I did some more listening. As somebody said before, here in this thread without dust cup they somehow shout.
So now I painted them with one layer of dammar and put those phase plugs from the picture in.
They sound very smooooth and clean now, but somehow not open. The bass i diffrent quite nice, maybe becouse of cone treatment. I don't know it's just completely diffrent driver and I must say I don't quite like it ,now except it is cleaner and more relaxed sounding. The highs are still missing,a lot of them are missing.
At this poin I must say how do I use this driver. It works in 60 litre bass reflex enclosure with rectangular port. I'm using pass band filter that is 4mH coil, 10R mills resistor and 2uF Siemens MKV cap in paralell and in series with speaker.
I was very satisfied with the highs of Fostex with this circuit, it was 95% as a good tweeter, almost nothing missing.But now it is some 60%. Highs are rolled off.
I'm thinking what may couse it. Maybe the gap between phase plug an the cone is too big. It is about 1,5-2mm around. Maybe I will shorten the plug to make it thicker, it has exponetial shape.
Or maybe the shape should be strait , not exponential?
>Illusus
Can you post the pictures of your phase plugs?
Bartek
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