Buschhorn Driver Upgrade...

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#64
Finally got some time free from work and pushed forward on the speakers. 😀

Here are a couple of pics showing construction of the sloped top and the curved interior bit.

Most of it's MDF, but the front panel is birch so I could drill and tap for machine screws to hold the speaker on.
 

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#66
Aengus, excellent work!

You might want to consider Dremel'ing some cutouts between the taps in order to let the driver vent somewhat better. I found that an improvement.

An externally hosted image should be here but it was not working when we last tested it.


This is an older picture, I don't use any sheep wool or other material in the CC any more. The FE108EZ wants acoustic impedance more than anything else IME.

Best regards,

Oliver
 
#67
Hi Oliver

Thanks for the note. I have relieved the inside with a 45-degree router bit, but it doesn't show clearly in the low-res photos. I started it at about 1/3 of the way in from the front, and it just covers the screw-holes on the inside, so that's probably about as much relief as I can give it.

I hadn't planned on stuffing the chamber, just putting thin (~2mm) self-adhesive felt on the walls. I'm hoping it will tame a certain brightness I'm hearing, but that of course may still be break-in as well.

I do have to come to some arrangement about internal finishing, since my wife has some peculiar aesthetic that is against large woodworking clamps on the furniture 🙂
 
#68
Thanks for the note. I have relieved the inside with a 45-degree router bit, but it doesn't show clearly in the low-res photos. I started it at about 1/3 of the way in from the front, and it just covers the screw-holes on the inside, so that's probably about as much relief as I can give it.
Click to expand...

Ah, sorry, I didn't see that. All is well as long as the driver can breathe properly. 🙂


I hadn't planned on stuffing the chamber, just putting thin (~2mm) self-adhesive felt on the walls. I'm hoping it will tame a certain brightness I'm hearing, but that of course may still be break-in as well.
Click to expand...

If I were you I'd make sure it's removable. My horn Guru told me that any stuffing in the CC is disturbing the acoustic impedance, and the FE108 seems quite susceptible to that. So I ripped out everything, even the small felt patches around the driver. They immediately gained an improved hear-through quality by doing that. Now, mine seem properly run-in now, so the felt could make a positive difference during that period for you. You can tackle a lot of the brightness by positioning.


I do have to come to some arrangement about internal finishing, since my wife has some peculiar aesthetic that is against large woodworking clamps on the furniture 🙂
Click to expand...

No problem as long as you can reach inside through the driver's cutout. 😉

Ah, BTW: you can improve clarity quite a lot by using a snubber parallel to the driver. I use a 8.2R resistor and a 0.47uF cap in series, this small network tackles the driver's inductance. Just make sure you use decent caps. I tried the following types:

Wima MKP10, 2 * 0.22uF in parallel -> very clear and very bright
Wima MKP4, 2 * 0.22uF in parallel -> not as bright, somewhat lower midrange forward, gives a bit more 'tubey' sound
Mundorf MCap 0.47uF -> nice bass, but slightly coarse treble. Boogies better than the others.
Solen FastCap 0.47uF -> the worst of all in this application
Audyn-Cap Plus 0.47uF -> after run-in they just do it for me. They match the drivers in every aspect, even run-in time. 🙂

All of the above is, of course, IMHO, etc.

Best regards,

Oliver
 
#69
Here's a shot showing the "clamped mono" setup I'm currently listening to (hey, maybe I can start a trend).



Coredump said:

If I were you I'd make sure it's removable. My horn Guru told me that any stuffing in the CC is disturbing the acoustic impedance, and the FE108 seems quite susceptible to that. So I ripped out everything, even the small felt patches around the driver.

and

Ah, BTW: you can improve clarity quite a lot by using a snubber parallel to the driver.
Click to expand...

Oliver, thanks for the advice. I have fastened down some sample bits of the felt and will test to see how easily it comes off after 48 hours or so.

On the snubber n/w, I may well try it once I think everything has stabilized.

Thanks again.
 
#76
I see that the Buschhorn MKII is much more used with the FE108ez than the Fostex recomended... I'll order my FE108ez tomorow, and I'll start with the Fostex enclosure first. I think this will be better for me because the enclosure will be only 15cm away from the wall, and far from the room corners.
 
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