EAR Primary Drive Speakers (Open Baffle)

[Puffin]

I have obtained a pair that are said to be prototypes. They both buzz to differing degrees and I am trying to cure this. The design is very unusual in that the bass driver has it's cone attached to a large cardboard baffle which was designed to extend the bass response in this open baffle design. This works to good effect, but as I say there is some buzzing, possibly some voice coil rubbing as well (in one).

I will try to add some pictures. The "baffle" is not securely attached to the outside of the frame, but the top and bottom and sandwiched into the frame which seems odd to me as this would/might cause the rubbing as it is not secure in the same way as a normal cone.

If anyone has any suggestions as to "fixing" these it would be appreciated.

 

[lowmass]

By "fixing" I assume u mean the buzzz?

I have built a number of bass panel protos myself using similar materials. One was actually cardboard the other was a plastic material that looks a lot like cardboard. In fact I think thats what they are using here?

The materials are quite heavy and I had my own motor design rather than use a standard cone glued to the "board".

Anyway I suspect any buzz you hear is going to be a loose glue joint OR a setion of the frame rattling against another.

I found the best way to locate a buzz is to use a frequency generator to get right on the frqency that excites the problem. Then use a tube from a paper towel, hold to ear and scan the area till buzz is isolated.

If dont have a freq generator then its a bit harder and trial and error.

Anyway I used cheap foam tape from hardware store to sandwich buzzy frames and there is some latex foam in a can u can spray on small areas.
This foam is similar to that "great Stuff" urathane insulation foam in a can BUT its not the same. Its actually a latex foam and is very fragile and easy to remove if needed. Its also very "lossy" in its mechanical property meaning its quite a good damper material.

 

[sreten]

Hi,

I'd suggest the builder has not thought all the problems through.

There is no justification for thinking they can be fixed to work well.

FWIW I think the builder has made a pigs ear out of the bass
end, and you know the saying, a silk purse is not possible.

rgds, sreten.

 

[cochleus]

A'pigs ear',that's what I hear..
Don't do it...
But, those who dare to advance...
That's what I'll bet...
Will succeed... dare we chance.

 

[Puffin]

Well I have sorted the buzzing/rubbing by resorting to a very expensive solution.......err....home made wedges. They are sounding great. Now to make a removable baffle and trim the wedges.

 

[tyu]

Vary good job.........I bet they sound good

 

[Toaster]

Interesting. I remember looking around a pair of those at a hi-fi show a few years ago to see how they worked. They looked too slim to be using conventional bass units. It does seem a bit crude. Surely better just to use, say, a pair of Peerless SLS 12" drivers for each channel?
I thought they sounded quite good, but wasn't that keen on the treble.

 

[Puffin]

Hello Toaster. I suppose it depends on a lot of factors as to whether you like a speakers balance. I think that despite the fact that the tweeter is horn loaded that it is pretty sweet and does not make itself stand out. It will also depend on the source material played and the room they are being played in.

I have tried them in my lounge and my dedicated listening room. They sound slightly different, but the fundamental character remains.

IMO they do a lot of things right. The bass is very good, tight, fairly deep and not boomy. The mid-range integrates very well.

As a free gift I am very happy, the trouble is do I prefer these or my Lampizator P17's

 

[Calvin]

Hi,

it looks to me as of they simply tried to enlargene the original diaphragm area in that they glued the flat blue piece to the membrane.
I'm wondering about two things ...
a- what happened to the original surround of the driver?
is it still there, and does the surround maybe contact the blue panel when asked to perform larger excursions?
b- is there no surround for the blue panel? If not, I don't wonder about buzz and rubbing. The high mass of the panel -in relationship to the original membrane- and it's position far off of the spider and original surround must lead to a tilt and a non-pistonic movement. I'd think about how to add some means of 'guidance' for the blue panel. Maybe one can find a soft tube (hose) and cut it in half, to use it like a (partly) surround, or one finds suitable thin metallic flat springs, or ...

jauu
Calvin

 

[Puffin]

Hi Calvin, just for the record I believe the material that the "planar" panel is made from is Correx a sort of fluted construction made of plastic. I originally thought it was plasticky cardboard. It seems (although vision is severely restricted) that the original cone surround is bonded to the panel. The front surround of the basket is bolted to the main frame as shown in one of the pics in the original post.

There is no surround for the planar panel. It is pinched in place in each corner, it is not in contact with the frame at the sides or top and bottom. I think this is why the voice coils were rubbing, and I assume either something the designer was aware of and thought "this is something that will hopefully not happen for some years" or that they were cavalier of the consequences.

"and it's position far off of the spider and original surround must lead to a tilt and a non-pistonic movement"

Yes, spot on. I have been considering permanent fixes, but I think that as the wedges are doing a brilliant job, can be re-positioned if neccessary, and cost nothing I am inclined to trim them and then add a removable frame/cover.

 

[lowmass]

The idea with the surround connected to the "blue panel" is likley to decouple the cone from the panel probably above about 200 hz, from there the blue panel can be tuned by size ,shape, and termination points, to get a rise in bass response to offset the dipole cancilation.

This type of panel uses its stiffnes rather than its tension to achieve the nessasary rise in bass output. Such panels tend to have a thickening of sound due to resonant issues between about 150 and 400 hz. I suspect the designer was aware of this and by mounting the panel to the cones surround this problem is neatly sidestepped and the bass rise below 150 hz is exploited.

By putting wedges in at various places you will alter the termination points and likley alter the frequency response a bit around 200 hz give or take a few. This may show as a bump in response around 200.

In my own design along these lines this was a trouble spot that often sounded great on rock and pop music but made everything else sound a bit thick.

 

[Puffin]

Interesting. I am not a speaker builder, However (I have built some back loaded horns and some open baffles) I have no measuring equipment and no technical expertise so basically "trust to luck" and hope that they will sound ok. I am sure this will horrify some. The EARs sound ok to me and I do not discern a response that is vastly different to the "un-wedged" sound. What is it they say "listen with your ears" as measurements are not the whole story?

Maybe I am lucky in that I listen to stuff with good bass content, anything with a Jazzy tinge, Jazzy Ambient, Jazzy Electronica, Acid Jazz, e.g Nils Petter Molvaer, Wolfgang Haffner, Lars Daniellson, Alien Chatter, plus Dub music (more horror I hear some say)

 

[lowmass]

listen with ears, verify with measurment, BUT in the end make sure your pleasing the ear not some technical belief system ha.

Yea often the differences are subtle and can go un noticed for a time. But time tends to reveal issues.

It may very well be that your arraingment changes things very little and it really isnt different enough to matter.