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sfdoddsy 31st January 2013 10:01 AM

Mounting an RD50
My impulse purchase BG RD50s arrived today. I was surprised by how much they weigh, and by how they are not as tall as I was expecting.

Anyway, I'm trying to work out the best way of mounting them. Initially I'll test them baffleless like StigErik crossed to the H-frame subs from my digiOrions.

The weight makes my thought of a simple folded perspex baffle like my bedroom dipoles seem dangerous.

So assuming I need a baffle, do people mount them from the front or from the rear?

Mine are used and didn't come with any kind of gasket, but the various knobs and stickie out bits on front and back are already as annoying as the ones on my Neo10s and 3s.

Why don't BG give us a nice flat surface?

StigErik 31st January 2013 10:22 AM

I'm doing some experiments with a baffle for my RD-75's. I have hung the RD-75 from the ceiling as before, and just attached two boards, one on each side, and on the front side of the driver, making the baffles flush with the front of the driver. Very simple.

sfdoddsy 31st January 2013 11:32 AM

1 Attachment(s)
I have a warehouse type room so could hang them from the beams. I even have pulleys already. But the ceilings are very high. Aesthetics are kind of important and dangling them low enough to be at floor height will look a bit odd and possibly interfere with the screen.

Are your boards flush with the edges, or flush with the central section?

How wide is the baffle? Given your success naked, I'm a little surprised. Although given our terrible desire to fiddle I guess I shouldn't be. I now have my digiOrions, Plutos, a pair of Duevel omnis, a narrow baffle 4 way OB prototype using Neo10s and Neo 3, a wider baffle of the above with drivers arranged horizontally and my simple two way perspex OBs all splayed around the room.

Plus I'm considering pouncing on some cheap HiVi M8s for mids to go with the RD50s, although the reason for getting them in the first place was to have a simple system like yours.

Oh, and pair of Apogee Duetta Signatures are on the way.

My lovely partner has gone from enjoying my massive downstairs lair to hating it as speakers expand to fill the available space.

StigErik 31st January 2013 11:42 AM

My boards are flush with the central section of the driver. They are 20 cm wide each.

This is just an experiment I'm doing, have not decided whether I like it or not. Frequency response and polar pattern is much worse than the naked driver, but the low-end efficiency is increased by 10 dB. This would lead to less distortion.

sfdoddsy 31st January 2013 01:59 PM

How much EQ do you use on the bottom end now to get down to 200Hz?

StigErik 31st January 2013 07:51 PM

Actually, I have to attenuate around 10 dB at 200 Hz. The response at my (very short) listening distance rises 10 dB from 1k and down with the wide baffle.

StigErik 31st January 2013 08:10 PM

2 Attachment(s)
This is how my wide baffle experiment looks like, and the EQ curve. There is a deep notch around 1 kHz which is caused by the baffle. It moves in frequency with changed baffle width.

gworrel 1st February 2013 02:52 AM

BG recommends a 12" wide baffle as a minimum.

I am using a pair of RD75s hanging bare except for some pipe insulation, crossed over at 280Hz to 4 15" woofers per side mounted on 24" wide baffles. They sound great.

I think you would want to mount them from the rear, though just attaching some panels on each side as StigErik has done makes sense given the long cutout needed in any one-piece baffle. Some foam weatherstripping should seal the gaps.

Mine sound so good it is tough to get motivated to experiment. I was at CES and listened to some ridiculously expensive speakers and didn't hear anything clearly better. I'll be curious to hear your thoughts.

sfdoddsy 2nd February 2013 03:56 AM

I have them running naked, using the H-frames from my Orions for bass.

In my room (very large) the low two-way crossovers mentioned here won't work out.

They sound quite good, but sound better crossed upwards of 400hz.

A baffle would probably help, but I think an array of mids would be a better bet.

sfdoddsy 2nd February 2013 02:37 PM

Sorry to reply to my own post, but I can't find the edit button.

I've done extensive listening and quick and dirty measurements. It seems the RD50 isn't as suited as the RD75 to the kind of setup StigErik and gworrel are enjoying.

The issue isn't so much the FR. I've been able to EQ the RD50/H-frame combo flat fairly easily. Flatter than my Orions.

The problem is that the response varies significantly with slight changes in distance and vertical listening position. Lean forward and they are lively. Lean back and they are mellow.

No doubt a large part is because I sit much farther back (4.5m) than StigErik's nearfield position, and the line is not as tall. Plus the bass is a dipole point source whilst the mids and up are a line source and hence have different radiation patterns.

But given one of main reasons I'm trying this is to get consistent response whether I sit up or flop down the results are not encouraging.

As mentioned above, a line of bass/mids would probably help. As would using RD75s instead of RD50s.

But so far the experiments isn't a success.

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