Feastrex Fun

[Nelson Pass]

You could use smoother edges on your Feastrex add on panel, better for diffraction.

It doesn't show on the photo, but the edges are beveled at 45 degrees.

To answer the other question, the PHL is open also, although the
panels have 12 inch wide by 30" high panels at the bottom sides
for support and a little more baffle distance for the woofer.

I'll get back later with some more data after the system settles out
a bit, and then we'll put the Lowther PM6A's (Ticonal with 15 ohm
silver voice coils) in.

Also there will be other woofers shortly, as I think the resonant
frequency is a bit high on the PHLs, and I think I can do a little better
with 20-25 Hz or so.

 

[pdan]

A Klein Horn Beard OB.


(I've no idea about the PHL (nor feastrex, for that matter) ... perhaps it could make for a decent pleasure band driver, with something else for the lowers?)


Cilla

 

[DaveCan]

A Bigger is Better OB Sweet!!
Dave

 

[bvan]

I'm curious if anyone out there that has heard the Lowther PM6A and also the Bastanis Prometheus could offer any insights into their relative strengths?

I know they are a different design, the Prometheus having a dipole tweeter operating above 10/12k, but price wise they are the same ball park and it might be that I have to make a choice between them unheard.

Many thanks

B.

 

[KevinHeem]

Kind of plain looking. You might want to "pimp em out" a bit. Bevel the edges, round the top corners, fill those screw holes, prime and finish in Ferrari red lacquer...tight dog!

Let me know, Kevin

 

[Nelson Pass]

Naaah, these aren't for public consumption. I'm going to be swapping lots
of drivers in and out and exploring crossovers and diffusors.

If I want Ferrari red, I'll buy a Ferrari

 

[Salas]

Naaah, David Wilson beat you in to the Ferrari part.

Go for a Labo.

 

[Nelson Pass]

I went through my red sports car phase twenty years ago. Now I drive
a white Ford, and listen to plywood speakers.

 

[Cal Weldon]

Hear, hear!

'cept mine's black.

 

[KevinHeem]

Naaah, these aren't for public consumption. I'm going to be swapping lots
of drivers in and out and exploring crossovers and diffusors.

Having become a student I follow. Having read this thread, I found humor in the irony that your speakers are 4' x 8' - 2' plywood sheets with two holes. My post was in reaction to the humor I was feeling, nothing more.

Take Care, Kevin

 

[Nelson Pass]

My post was in reaction to the humor I was feeling, nothing more.

Of course. I interpreted it as such.

 

[Bunpei]

The D9nf is mounted in a flat 4 foot wide by 6 foot high open baffle,
sharing the space with a PHL 18 inch woofer.

Dear Nelson,

I'm interested in open baffles that mounts Feastrex.
I'm afraid my question is bothersome as you might have already explained the baffle before somewhere.

What kind of wood material do you use?
How thick is it? Do you make any efforts to suppress unintended vibrations?
Thank you very much in advance.

Best regards,
Bunpei

 

[Nelson Pass]

These baffles are Chinese Birch Plywood, 3/4 inch thick.

There is nothing else special about them, except that they have
been constructed with removable driver panels so that I can
change out full-range and bass drivers without much work.
I have small side panels 16" inches deep and 30" high at the
back surface tapering down to 24" to support the baffle and
provide a longer path for the woofer. These are removable and
replaceable.

They are about 6' from the wall in a 30' X 30' room with a vaulted
ceiling.

I built the panels 4' X 6' as my maximum size, and as I acquire
information about the performance I can cut it down to smaller
dimensions and compare the results. I have about 10 types of
woofers to try and about 10 different full rangers.

There is a very adjustable active crossover and equalization
circuit for it, the result of my previous baffle efforts.

 

[Salas]

Good luck with your test platform, at a point I am sure you gonna hit best synergy. Just don't be afraid to cross at 200Hz.

 

[Bunpei]

Dear Nelson,

I appreciated your prompt and detailed reply very much!

I understand that you use the OB as your universal and common test bed for checking native performances of your various units.

I think the thickness 3/4" is enough, however, the big woofer may have a strong power to produce uninteded vibrations on the baffle plane. Don't you observe this?

Bunpei

 

[Nelson Pass]

Yes, but I would not use the word unintended, since it is
expected - the woofer makes everything else vibrate as well.
It remains to be seen whether it is a problem.

 

[KevinHeem]

Three saw cuts around the woofer fixture, and another set of legs on the back would separate the two drivers. Yeah I know, now what have you got?

 

[Vix]

Hi Nelson,

Big baffles they are. Not a chance of surviving WAF attack, at least in my home. So, how about a different approach: tall and slim, as Graham did here: http://www.audiocircle.com/circles/...gt05160htgja4&topic=57919.msg524884#msg524884

And a question: Assuming that you are using F3 amp for the fullrange driver, can you make a 2nd order high-pass crossover, by adding a suitable small capacitor at the input, and by decreasing the ouput electrolytic capacitor. I am asking this because it could be possible to replace that elco with some MKP type, and the F3 would sound even better?

Thanks

Vix

 

[Nelson Pass]

Having already noted the advantages and disadvantages of
slim, I felt the need to explore better extension for the full range
with a flat baffle. My 2 foot wide units allowed the PM6A and
the D9nf to make it down to about 180 or so. You can imagine
what happens to narrower that that. The taller 4' wide version
falls off about 60 Hz.

Certainly you can use the input 10K of the F3 as part of a
filter, but the impedance of the full range jumps up pretty high
at resonance, so the output cap is not that effective, unless you
load the output.

 

[Vix]

Thanks!