Someone to build low frequency shelf filter?

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etflutes

New member
Joined
Feb 26, 2007
Messages
4
Location
Humboldt County, CA
Hi folks,

I'm new to the forum and I hope that this is an appropriate place for this posting.

I've just remodeled my very small studio space, and to help with space issues I've soffit (flush) mounted my Dynaudio BM5A monitors. Typically, I don't think these are necessarily recommended for soffit mounting, since they have the bass port in the rear, but the results so far are surprisingly good (to my ear).

However, there is an exaggeration of the bass response as a result. I read about "baffle step compensation" and the possibility of building a special filter to attenuate the extra bass resonse--in fact I have a schematic that was provided on another forum by Thomas Barefoot.

However, I don't know the first thing about electronics and building the thing myself is pretty much out of the question at this point.

Is there anyone out there who does this sort of thing commercially? Clearly there are a lot of DIY users on this forum and Thomas recommended asking here to see if I could find someone to build it for me.

Any takers?

If so, you can PM me or e-mail me (or post an answer here) and we can discuss the nitty-gritty details. Obviously I'm willing to pay for the service :wink:

Many thanks!

Geoffrey
 
sofit mounting will increase bass. Thats true. IMO at that point it's more of an acoustic issue. You could do something as simple as put up some bass traps from auralex or insert brand here or even run a an EQ in between your speakers and the output of I would assume a daw? Then you can take out completely or lower the frequencies you want. In the long run would help more then just a simple Hi pass filter. PLus you can get a decent Graphic EQ for not mucho money...
 
Pucho, mi amigo... that is not what the man wants. I believe he is after someone to make him a "baffle step compensation" gizmo, so let us help him out.

Geoffrey... post a schematic of what you want and someone will nail one together for you.

peter
 
well, actually that speaker was designed for free-field use, so it must have baffle step compensation built-in to the crossover. you could try to remove the compensation, instead of putting another filter on top to negate it. maybe add a switch on the back to defeat it. easy?, probably not. fun? yes.

mikep
 
[quote author="peter purpose"]Pucho, mi amigo... that is not what the man wants. I believe he is after someone to make him a "baffle step compensation" gizmo, so let us help him out.

Geoffrey... post a schematic of what you want and someone will nail one together for you.

peter[/quote]
you just want to stare at another schemo :green: :thumb:
 
it's like looking at playboy I understand...

well here check this out... Has some good info here plus a schemo.


http://www.t-linespeakers.org/tech/bafflestep/index.html
(This page got the schemo)
http://www.t-linespeakers.org/tech/bafflestep/bstepcompo.html

or if you just want the schemo part

circuit.gif
 
Humboldt county, eh? I've been there a bit... Eureka/Fortuna mainly... -The really BIG cities!!! :green:

Pucho, isn't the schemo which you posted an LF BOOST schemo? -It looks like it to me. -If the monitors are soffit mounted he'll want an LF CUT...

Keith
 
Wow! Great to hear so many responses--very encouraging.

Fiddling around with the inside of my monitors is probably not a good idea. I've never done anything electrical beyond screwing in a lightbulb!

I'm pretty much open to whatever will work, be it a step filter or EQ or whatever. Definitely a cut and not a boost, however. There is a switch on the back that lets me cut 2 db off the bass, but it is not enough. Room acoustics is probably not a major factor at this point. John Sayers (studio designer) did the modification plan for my space and it includes non-parallel walls, bass traps, helmholtz resonators--the works. I'll be fine-tuning the space with the ETF software but I wanted to address the monitors first.

I was proceeding on the assumption that the filter was what I needed because that is what everyone said was needed (over at John's acoustics forum). When clueless, take advice. I've posted the schematic from Thomas Barefoot and welcome any input. If I can make a desktop "box" that I can run my cables through on the way to the monitors that would be great but I have no idea what is necessary in terms of parts or how much labor would cost, etc.

My dad is retired and lives nearby, and he has had some limitied experience with this sort of stuff (about 40 years ago) and he looked at it and thought we could tackle it, but I'm worried that it might be a loooonnnggg project and I need it sooner than three months from now.

Just realized...I don't know how to do attachments! How can I post the GIF file?

[/img]
 
[quote author="SSLtech"]
Pucho, isn't the schemo which you posted an LF BOOST schemo? -It looks like it to me. -If the monitors are soffit mounted he'll want an LF CUT...

Keith[/quote]

DOh!!! I'm thinking hip-hop.. Forget me.. Time for some PG tips w/honey.
 
By the way, can anybody tell me if this unit would serve the same function as a low frequency shelf filter?

http://www.marchandelec.com/wm8.html

I don't know enough to make the finer distinctions here but this seems as though it was made for this sort of problem. Any thoughts?
 

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