Experimenting with damping material

I thought I might share my experiences with a novel new type of damping material for use in the bottom of the Singular cabinets.
It is exceptionally dense. Yet rather difficult to keep in place, particularly during loud passages. Rock music however can become a problem with some damage to the rear of the cone if listening for prolonged periods.
The only downside I can see is a peculiar low frequency rumble that appears occasionally about an hour after the amplifier is switched off.

But seriously now, the cat has taken a liking to these, I need to make some kind of screen to keep him out.
Any suggestions before I panic the cat and he damages my drivers?

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Hi Mike,

The only downside I can see is a peculiar low frequency rumble that
appears occasionally about an hour after the amplifier is switched off

Leave the amplifier on ?
Peter

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Hi Mike,

The only downside I can see is a peculiar low frequency rumble that
appears occasionally about an hour after the amplifier is switched off

Leave the amplifier on ?
Peter

I was thinking of that Peter, but now that soothing purring noise is growing on me.

Perhaps I should lurk outside with the remote control and see what the cat thinks of Queen at high volume when he puts his head in the back.

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Ha ha ha Mike.. :lol:

What a great joke and story you are telling.

The cats name? Romy or Boomy?

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Vincent, even though he still has both ears.
From the Don McLean song.

A long story about the origin of the cat's name follows.

I was staying at a friend's house after a party and wanted to make some breakfast when I discovered a massive tower of dishes in their kitchen. Her and her brother had used every single bowl, cup, plate, saucepan and storage container in the house to eat from. They were both feuding with each other like only a brother and sister can and neither would back down. This was a truly massive pile of dishes, they were even useing saucepan lids as plates. There was nothing left to eat from.
I had woken up early and washed a few to eat breakfast from, then I decided to keep going until one of them woke up. So I played that side of that Don McLean record, over and over, very loud. I kept playing it trying to wake one of them as I washed the dishes. Both of them throught it was the other one doing it, they had forgotten I was there and they were determined not to give in to each other.
Well, I played the same side of that record at least 6 times as I washed those dishes. I know it was well over 2 hours with Don McLean blasting away. They must have been going insane, I know I was. I ended up washing all of the dishes. So what happened in the end? Well he is my brother in law and she is my wife. The cat was a 30th birthday present for her.

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Mike

Thanks God the cat has both ears left, as I have noticed cats without ears at all.

Hey...so you are a pro dishwasher? Don't advertice that too much. You will soon enough be an object for head hunters for diswash manager jobs from all over the world....and just imagine if the employer do not have any playback system, Vincent would be out of job.

Therefore this job offer: I have a playback system and also piles of filthy pots and pans to be cleaned. I have room for both you and Vincent. Vincent will be a nice tweak for my SWINGs... :grin:

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Hi Mike,

Any suggestions before I panic the cat and he damages my drivers?

Anything airy and non resonating will do in this case. A stiff metal structure as used to strengthen concrete comes to my mind.

Do replace the damping for clean material though, you'll never know what the cat was doing down there! It sure does like your music, or is it the opposite... :grin:

Bert

--
BD-Design - Only the Best!

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Do replace the damping for clean material though, you'll never know what
the cat was doing down there! It sure does like your music, or is it the
opposite...

Bert

I certainly will replace it. That is just temporary material anyway. I was impatient and cut up some pillows for that material. Thanks for the inspriation Bert, That type mesh they use on the back of police vehicles here, I can two wooden dowels on each to make bars like a jail. I can fit them to small slots cut in the outside of the MDF. The whole cabinet will soon be covered with thin plywood.

Just imagine what might have happened if sand was used in the bottom of the cabinet.. Oh dear.... :no:

I have just fitted phase plugs to the Fostex and listened to some Xavier Rudd (an Australian blues guitar & didgeridoo one man band). The cat does not like the didge. I like the mid-highs better with the plugs, even with a head-cold.

Fortunately the cat hasn't gone near the speakers since, I think I might have solved the problem.

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I've damped driver the basket a bit more and added some wooden phase plugs, The phase plugs really cleared up the high end.
I found I had over-stuffed the back chamber, there is much less midrange coming out the back vent now.

The high highs still weren't there so I added a Fostex FT17H yesterday with 1uF polypropylene capacitor.

Here is a picture of what I did to the driver, 5mm self adhesive felt on the back of the magnet, magnet to basket joint filled and shaped with blu-tac, 5mm felt inside the basket legs, bitumen and foil on the outside of the basket legs. It seems to keep things in control better at high volume now.

I neeed to play with the filter to get the tweeter right next. I find them too "bright". I'll try adding an inductor to roll them off more steeply at 12dB/octave at about 10kHz.
I want to avoid any filtering on the fullrange driver, it drops off very rapidly above 12kHz by itself.
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Hi Mike,

Thanks for the update, tough job! :wink:

I neeed to play with the filter to get the tweeter right next. I find them
too "bright". I'll try adding an inductor to roll them off more steeply at
12dB/octave at about 10kHz.

Try to add a resistor in parallel with the tweeter (around 22 ohms) to dampen it a bit, should make it less "present". Instead of 12dB you could also use a smaller capacitor (470nF) to tune the high frequencies so that the overlap remains a bit wide for freshness. This by itself willreduce the output at its lower frequencies.

Bert

--
BD-Design - Only the Best!

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Try to add a resistor in parallel with the tweeter (around 22 ohms) to
dampen it a bit, should make it less "present". Instead of 12dB you could
also use a smaller capacitor (470nF) to tune the high frequencies so that
the overlap remains a bit wide for freshness. This by itself willreduce
the output at its lower frequencies.

Bert

the tweeter is 3.5dB more efficient than the main driver.
I have a bag of 1uF capacitors so I will put another one in series to drop the value, thanks Bert, I didn't expect such a quick and helpful answer.

I found another interesting cabinet for drivers similar to the Fe207E. a double back vented reflex horn type thing. Search for: frugal horn spawn Bruce.
It might have potential for AER drivers. Slightly more complicated build than the singulars but a similar amount of material.

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Pretty good advice there Bert, I added another uF in series, Much nicer, more subtle and integrated, it has lost a little sparkle, I might try for something in between next and see how that sounds.
I just finished watching Diana Krall Live in Paris DVD, I see what they mean about the singular and the double bass, Wow! Double Bass is so real. Vocals are great too, But the piano still sounds very much like a pair of speakers playing a recording of a piano. Still pretty nice considering the price of the drivers. I'm starting to really enjoy these speakers now. They like a bit of volume, somehow they seem clearer that way. Perhaps they need more hours of use to loosen up.

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Pretty good advice there Bert, I added another uF in series, Much nicer,
more subtle and integrated, it has lost a little sparkle, I might try for
something in between next and see how that sounds.

Using two capacitors in series doesn't improve quality....the type used does matter too you know. Loosing sparkle means bad sounding capacitors (you now have twice the sound of that capacitor!

Vocals are great too, But the piano still sounds very much like a pair of
speakers playing a recording of a piano.

Perhaps the piano is recorded....did you see where they put the microphone? :wink:

Bert

--
BD-Design - Only the Best!

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Using two capacitors in series doesn't improve quality....the type used
does matter too you know. Loosing sparkle means bad sounding capacitors
(you now have twice the sound of that capacitor!

Yes 2 capacitors in series is not good but it's what I had on hand. I bought parts for a 10kHz 12dB/octave crossover, works out nicely with 2uF and 1uF capacitors, I was going to use 2 of these in Parallel (half the capacitor sound?) for the 2uF.
I used axial leaded metallised polypropylene capacitors. 1uF +/- 10% 250VMP, no other markings, yellow. I measured them ant picked matched pairs (within 1%)
Not a famous brand but they would have to be better than an electrolytic.
I should buy some Wika capacitors and see if I can tell the difference.

Perhaps the piano is recorded....did you see where they put the
microphone? :wink:

It's all recorded isn't it? :yes:
She was sitting at a Steinway, but it certainly didn't sound like a Steinway. It was rather flat, without that rich resonance, like an electronic piano. I thought it might be the DAC I am using (the one in my AV receiver)
Interesting... I didn't see the microphone for the piano... But you'd expect with the effort of bringing in a small orchestra an extra microphone and recording channel would be nothing. A Pianist/Singer pretending to play a piano would be very strange. I think I'll have to watch it again, with less Whiskey this time. :drinks:

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Hi Mike,

I found another interesting cabinet for drivers similar to the Fe207E. a
double back vented reflex horn type thing. Search for: frugal horn spawn
Bruce.

I have seen those designs but they are HUGE...good thing for using them with AER's (or Lowthers) is their relative short path length giving good mid-bass.

Thanks for the link though...

Bert

--
BD-Design - Only the Best!

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I have seen those designs but they are HUGE...good thing for using them
with AER's (or Lowthers) is their relative short path length giving good
mid-bass.

Thanks for the link though...

Bert

Not quite as big as you might think, they use slightly more material than a pair of singulars - One 8 by 4 foot sheet per speaker plus some s****s to reduce the compression chamber volume. Overall not as deep but about a foot taller. It all depends on the layout of the room and the amount of jewelry the Wife has been given lately.

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Experimenting with damping material (Singular)