Nagaoka Swan cabinet resonance HELP!!

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Hello,

Long time reader, first time poster.

I just finished building a pair of Nagaoka Super Swan (D101S) using the Fostex fe 108EZ drivers. This is my first speaker build in the past 15 years, and I don't really know too much about the various aspects of speakers and basically just built the enclosure exactly as layed out from the plan (except I used cheap Home Depot Plywood...sigh.)

It sounds really good (~20 hours of playing), I could hear more details about the ambience of the recording venue and it's really cool. Bass is unbelievable for such a small driver as well. I hope it keeps getting better with more break-in.

The problem is that there is a clearly audible resonance right around the human vocal range. It quite distracts from enjoying vocals. The effect is not as noticible with instrumental works, but again quite distracting with vocals.

Is there any way to get rid of the resonance? I have several idea but may be way off.

1. Add stuffing materials? Fibreglass to the inner sides of the head?
2. There is a funny hole on the body of the swan, do I fill that with stones?
3. Is this just an issue of not enough break-in? Should I just wait to see it gets better by itself?
4. I really hope it is not due to me using cheap plywood, because this means I am stuck with this resonance (I am NOT going to rebuild another one for the rest of my life, these are absolute a pain to build... :>)

Help me out...Any ideas are greatly appreciated...

Thanks!

Roger
 
Add stuffing materials? Fibreglass to the inner sides of the head?
A little goes a long way. I put a single piece of polyfill on the back of the head and a single layer of carpet felt on the mouth exit floor.


There is a funny hole on the body of the swan, do I fill that with stones?
I used sand.

Is this just an issue of not enough break-in? Should I just wait to see it gets better by itself?
Perhaps, the drivers need several hundred hours I have found to "smoothen"

I really hope it is not due to me using cheap plywood,
In all fairness this is probably the or part of the problem. Voids in the plywood and sometimes fillers in the plywood that are loose.

Hope you can sort them out, I have no issues with mine except I have yet to finish (veener) them.

Andrew
 
Thanks Scottmoose for the suggestions. I will try them after work today.

One more piece of information that I would like to provide, when I was sanding the cabinet using my random orbit sander, the cabinet tends to amplify the noise of the sander (resonate) when I sand a particular area (the hole area on the body of the swan), much like the same way it's resonating now. Does that suggest that it is the source of the problem?

I guess I will find out when I fill the hole anyways...

Thanks again,

Roger
 
What is detachable?

Neck from body?

Might be good to also try fishing a small piece of damping down into the neck hole and see what happens. Using a little retractable claw to remove it later. (not sure the name, but I used a tool like this also for fishing fallen bolts out of car engine compartments).

Not to dumb things down too much, but I will convey what I have learned from others on this forum: the rule of "halves," regarding damping. Insert some in. not enough? Double it. Too much? Half what you added. etc.

Good for fine tuning.

It is good to try to damp only one area at a time to perfection, the move onto others. Try to separate out each section's damping's effect on the music in your mind. Get that part of the music (or instrument) sounding decent, then move on to the next section that might be a problem. Decent is good enough, because after all sections are properly damped (and it really won't take very much), you will adjust them all at the same time to match each other and be "just right."

To echo other's comments, it is good to wait for the enclosure to "cure" a bit. The glue hardening and gradual panel dewarping affects the horn sound profoundly, especially of such a complicated horn path.

Try finishing the accessible inside areas of the horn with the same finish as used on the outside... it completely changes the resonance behaviour (depending on the finish).

I used "Tried and True" brand varnish oil on every surface in my old speakers. It works WONDERS...meaning, that I felt like I could head the petrolum unholiness in other finishes...by direct comparison.

Also, I was not being poisoned by the stuff. Major plus...

Ye Olde Schoole style shelllac is good also (likely better). Violin varnish, I hear is very nice. Have not tried it.

There are lots of options for finishing and damping. Many people other than me have explored them more exhaustively.

Tried and true linseed oil is pretty darned organic, and is somewhat edible, even. A good middle ground for use with Fostex (don't wanna out cabinet the driver...).

I have read multiple threads to this effect about the swans, that they resonate badly for a while, and then a few creative measures and simple waiting solves, for the most part, the problem. I never built them, (though I have the 108ES-II pinnacle driver for them...).

What is the rough specific gravity of your plywood? Cheap might not be a big issue, actually, if properly implimented. Sure, voids will mask ultimate resolution, and might add a little background noise to the sound (very small), but bad implimentation of good ply will warp the response to far worse effect. Can't throw money at it, only effort.... good implimentation of cheap wood still makes a pretty decent speaker, which it sounds you are after.

-Clark
 
Thanks Andrewbee and Blumenco for your suggestions! Now I have an systematic method to approach the "art" of adding damping materials to the enclosure.

Unfortunately, nothing is detachable anymore (everything is glued tight), so the only access to the inside of the swan is through the opening for the driver), so I can't add varnish to the inside...etc. but I can still add damping materials there.

Anyways, I have attached some pictures of the swan (with a picture of the hole that I was referring to).

Thanks!

Roger
 

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Hi Roger,

I filled the hole with sand then cut a patch of wood and glued in place.
As Clark said, coating the surfaces, particularly the insides makes a difference. I am partial to Shellac. Tape off the glue arrears and do not apply the shellac or whatever you choose too close to the lines as it may leech into the wood and spread into the glue area.

I built a pair of D-156 Swans a few years ago and loaded them with 166es-r's.
They are the same Swan design, just larger. I prefered the 101a's.

There is a lot more to speaker building than numbers and formulae.
If you take different types of plywood for example and rap them with your knuckles, you will hear differences between them, the different densities of the wood plies.
Different types of wood in different parts of an enclosure will make it sound different than all of the same type of wood.
As with so many things in life there is an art to it.
I am still learning more and hopefully will continue to do so .

Andrew
 
I'm listening to a pair of these as I type this.
Great sounding pair of speakers, a lot better than I had expected to say the least.
Built them out of baltic birch though, very carefully fit (no air leaks), with shellac inside and out, taped off glue lines like Andrewbee mentioned.
Mine are actually the Super Swan enclosures, modified to use with the 108ES-II drivers (bigger magnet).
They took a while, like a few hundred hours to calm down, break-in whatever you want to call it though.
Other than sand in the central cavity (I didn't drill mine, just built it filled/sealed).
I'm not using any stuffing, felt, or anything like that.
I like them better this way.

They are VERY sensitive to rooms, and placement though...
At first I wasn't expecting much from them, (didn't think they'd be near as nice as the Ron Clark Austins with 166ES Rs), just planned on using them as a second or third system, & put 'em in a small spare room which is square, hard floors & walls, very live.
I tried stuffing, damping, all kinds of heavy stuff on top of the body and head.
Horrible resonance, (in the vocal area, especially on a voice only cd), and too much bass (believe it or not....)
Then tried them in a much larger room to hear just how bad they really were...
In a damped ROOM, that's NOT SQUARE, and out away from the corners, so they weren't getting so much reinforcement from the walls, (with a good amp) they suddenly sounded quite nice.
After tweaking with placement (a lot) they truly sound beautiful.
They were the suprisingly favored speakers @ a local "listening party" a few weeks ago, and were in the midst of some pretty high dollar equiptment.
Dire Straits was jaw dropping from a 4" driver, but what I love is what they'll do for Yo Yo Ma, or piano/bass/drum jazz...
I don't think it "out cabinets the driver."
Robert
 
yeah...

Sorry for confusion...I meant to say:

to avoid using truely expensive Violin varnish and REALLY expensive woods... (meaning solid tone woods for instrument building).

Shellac, Linseed oil, BB and Plyboo are MUCH cheaper...and more suited to use with the Fostex drivers. From the little that I understand, the drivers are voiced with that sort of wood, etc. anyways...

I too planned on using my pair of 108ES-II in a similar style finishing on the cabinet as yours. Now, I might just import them to use as an "ultimate" set of computer speakers w/ sub.

But trust me though: I aint knockin the Super Swan, or the ES-II for a second...hearing that combo at CES several years ago blew my mind. Happy to hear that they are so enjoyable. I always thought they were a true giant killer.

-Clark
 
Thank you all for your suggestions and expert opinions!

OK, so for the following were done:

1. Filled the hole with sand (and created a mess in my basement in the process...)
2. Added a piece of fibreglass insulation to the back of the head.
3. Added small pastic feet to the base (it was not stable prior to that).
4. Did another 24 hours of break-in.

Well the cabinet resonance may have been reduced, making vocals more enjoyable, but it is still there. Don't know what changed (did the speakers improve or is this all in my head?)

One important thing I learned through all this is the importance of prototyping and not to finalize anything until I am happy with the sound. Now that I have finished the cabinet it is difficult to do some of the things you recommended.

Next steps: To experiement more with damping materials. I'll see what happens!

Thanks again,

Roger
 
Roger,

did you add any damping material at the bottom of the body below where the neck enters the body? IOW the point below the neck where the horn bifurcates.
It is on top of the bottom #16 and goes between #6 & #7, a rectangular piece of damping. I think I got the numbers right
 
Andrewbee said:
Roger,

did you add any damping material at the bottom of the body below where the neck enters the body? IOW the point below the neck where the horn bifurcates.
It is on top of the bottom #16 and goes between #6 & #7, a rectangular piece of damping. I think I got the numbers right

I second that: again, I have not actually built the swans, but on similar horn foldings, damping this point is the best place to start. (better than the head, because that tends to (Ymmv) attenuate HF resp. and speed.)
 
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