Have anyone removed dust cup in Fostex FE driver?

Status
Not open for further replies.
Jump to Latest
#41
in these 2 drivers the VC sits proud of the cone leaving a nice V to fill up
Click to expand...

I thought that the whizzer cone/ dust cap was rigidly fixed to the voice coil, but the main cone was connected to this assembly via a black rubbery compound, so that the whizzer cone could respond more freely to higher frequency signals without having the influence of the additional mass of the main cone to contend with.

Wouldn't filling this area stiffen this flexible coupling and modify the frequency response of the assembly? (de-sensitise the whizzer)

Correct me if this is not the case for these fostex drivers, as I only read this somewhere, and it may have been another type of driver.
 
#42
I made some phase plugs for my Fostex drivers. My friend is working with digital programable milling mashines and he did these for me out of aluminium. This is the first one. I want to try a couple of sheapes. There are much more highs and the sound is crystal clear with these fitted. Imaging and low level detail improved and the speakers are more smooth and relaxed. I will report how does it compare to diffrent shapes I'm going to try (maybe I will set a new thread about it). These are 33mm but it seems like 34mm would also fit. The height is 55mm.

Bartek
 

Attachments

  • 11.jpg
    11.jpg
    81 KB · Views: 460
#46
zygibajt said:
I made some phase plugs for my Fostex drivers. My friend is working with digital programable milling mashines and he did these for me out of aluminium. This is the first one. I want to try a couple of sheapes. There are much more highs and the sound is crystal clear with these fitted. Imaging and low level detail improved and the speakers are more smooth and relaxed. I will report how does it compare to diffrent shapes I'm going to try (maybe I will set a new thread about it). These are 33mm but it seems like 34mm would also fit. The height is 55mm.

Bartek
Click to expand...

Looks like the shape is pretty optimized. What is the shape of the sides?
 
#48
Just a quick question: how long should the tip of the phase plug extend? Should it be on the same level with the whizzer's outer surface?

I have seen phase plugs being level with, short of or longer than the whizzer. Is there a general rule concerning this?

Evangelos
 
#49
Looks like the shape is pretty optimized. What is the shape of the sides?
Click to expand...

I don't know if it's optimized. I will try a couple of diffrent shapes and will see which one I like better. I can't do any measurements becouse of lack of instruments, I will be examinating them only with my ears. The shape is straight 33mm untill some 2mm above the base of the whizzer.

how long should the tip of the phase plug extend? Should it be on the same level with the whizzer's outer surface?
Click to expand...

I personally have no idea, but I don't think it should be much longer than Whizzer.

Bartek
 
#50
bobhayes said:
I thought that the whizzer cone/ dust cap was rigidly fixed to the voice coil, but the main cone was connected to this assembly via a black rubbery compound, so that the whizzer cone could respond more freely to higher frequency signals without having the influence of the additional mass of the main cone to contend with.
Click to expand...

Bob,

I was looking at the review of the Konus Essence speaker on 6moons.com and Ted Jordan was talking about this very thing. I believe it's the Jordan drivers that you're thinking of.

Best,
KT
 
#54
Hey Dave,

Hey Dave,

Because you have designed and experimented with phase plugs and, as I understand, did some extended listening to Visaton B200's, you may be in a unique position to speculate on a question I have.

Do you think phase plugs would improve the HF response of the B200's? I'm thinking of the off axis dips in the 5k to 10k range (and above) on some response graphs I've seen. Or might the phase plugs(and dustcap-ectomy) risk loosing some of the HF extension?

Also, while you had the B200's did you run them past any of your test equipment(Fuzzmeasure)?


Thanks,

scottw
 
#55
Re: Hey Dave,

scottw said:
[Do you think phase plugs would improve the HF response of the B200's? I'm thinking of the off axis dips in the 5k to 10k range (and above) on some response graphs I've seen. Or might the phase plugs(and dustcap-ectomy) risk loosing some of the HF extension?
Click to expand...

My (untested) opion is that phase plugs on these would make quite the improvement (based on general results from every other speaker we have done). I've had lots of inquiries, but no one has decided to take the plunge yet. I'm not at the moment in a position to buy a set and do the experiemnts myself.

At least here in NA, the B200 is an excellent driver that is still flying under the radar of most people.

Also, while you had the B200's did you run them past any of your test equipment(Fuzzmeasure)?
Click to expand...

They were BFM (before fuzzmeasure).

dave
 
#56
Thanks for the info Dave.

Guessing it's just a matter of time before someone "takes the plunge" and operates on their B200's, and posts about it here. I doubt I'll be the first to try it.

Have you seen any/many occasions where adding a phase plug has reduced the HF extension?

thanks

scottw
 
#57
Generally removing a VC cap and putting in a phase plug reduces the effective mass at high frequencies allowing for better response, but if it's a very small percentage compared with the other parts of effective mass, then you may not see improvements.
 
Status
Not open for further replies.
Top Bottom