Psyd wrote:Hmmm, I could probably make a fortune making mufflers for grinders designed by a sound engineer, couldn't I?

Well, of course, if I hadn't given all my secrets away for free already! ; >

Oh, all you need to keep the grinding/crushing sound in is a plastic tupperware lid with a beanbag attached.

The beanbag keeps the plastic 'drumhead' from transmitting the sound...

No, you could make a fortune making custom exhaust pipes for grinders. Just imagine, multi-chambered mini-hoppers that amplify and shape grinding tones into mean growls. "Yeah, my two-stage racing hopper sounds pretty sweet when I open her up, dude."

Alright, so joking aside, I think that I have finally come to a couple of conclusions.

I really tried to make my cheap foam option work. The only problem was that it reduced the stability of the grinder. Every pull of the doser lever rocked the grinder back and forth in an annoying way. So then I tried to add systematic foam donut supports, which only helped slightly.



So I decided that instead of over-engineering, I would go back to the much simpler mousepad option suggested much earlier in this discussion. And it really is the best. I found an old one when I came back home and spray painted it black so it was more discreet..



I seem to have gotten pretty lucky. The clearances between the feet and the edges of the pad are quite small.

The grinder is still perfectly stable, and even this thin foam-ish mousepad seems to have a 100% effect on vibration isolation. Certainly, as sound experts have noted, there could be some other fool proof options, but I don't really think that they are necessary. The vibrations that the Super Jolly puts out aren't that strong - I think the transfer has a lot to do with it's solid feet and large weight. Put another way, I don't think that the displacement of the exterior surfaces is large enough to justify multi-layer isolation options (as fun as they may be to design ) It's mainly loud because of such a "direct" connection to the counter.

If you too have a Mazzer grinder... or any grinder... think about putting a mousepad underneath it. It will be quieter.

As far as the bean breaking noise... I'm still working on that. I think that I'm going to take Psyd's advice and stick a hackie-sack on top somehow. While a sound box of some sort might be the truly quietest option, I want to be able to see my baby. I think that the internal casing actually does a pretty good job of directing the remaining sound straight out of the top and into the doser through the chute. I'll post again with my final solutions (dare I say mods?).

I gotta tell you one more time though, I'm really happy with the mousepad thing. It's not like a quiet grinder was super important to me, but when it happened it was "woah, that's pretty nice."

I might try this with my Cimbali Max. It's a nice grinder, but really loud. Putting it on a mousepad might help reduce vibration transfer to the counter.

I think part of the problem with the Max is that it has a thin sheet metal housing rather than the thick cast aluminum of the Mazzer grinders, so it tends to resonate more. Maybe putting some Dynamat on the inside of the case would help too. Maybe this weekend I'll take a look into the case and see if there's enough room for some sound damping insulation.

Idea for an over designed surface noise canceling device for a grinding machine.

1. Place several pizo vibration sensors under the surface.

2. Add several larger pizo surfaces bonded to the surface and the substrate.

3. Drive the pizo surfaces in step 2 at 180deg phase from the signal from step 1.

4. Silence.

5. Put this in a grinder tray and make it cheap.

-C

CRCasey wrote:3. Drive the pizo surfaces in step 2 at 180deg phase from the signal from step 1.

4. Silence.

You just layed out plans for Bose noise-cancelling grinder feet, didn't you.

Dream big, you crazy home baristas, dream big...

My Mazzer Mini showed up yesterday and was ready for a roar grinding but could not be happier with noise it makes.. The pump on my Breville Espresso Machine is another story though...

That's true, it should be noted that I was talking about a pretty low amount of noise to begin with.

My Super Jolly has always been a lot quieter than a blender, loud stereo, etc. I could always carry on a conversation pretty well while grinding. With some counters I didn't need to elevate my voice to talk. I think I've heard cheap dishwashers louder. The Mazzer Mini, I assume, is even quieter.

I just like reducing the noises I can.

So far, dampening the noises coming from the grinder chamber has been ineffective. I haven't noticed a difference in different types of lids. I'm still thinking about things, though.

Johnny Kleso wrote:The pump on my Breville Espresso Machine is another story though...

See the above methods for quieting a grinder... Most of the noise from the pump will be the pump transferring vibrations to the frame, which transfers that movement to the large panels attached to the frame which, as you know, starts to move a lot of air around.
'Sound' is just a term we use to describe moving air whose frequencies fall into the range which we can perceive. Stop the thing that moves the air, it gets quieter. Anything that interferes with that transfer of vibration will make it quieter. Rubber isolators on the motor (I may have a coupla hundred lying around...), some padding of sorts between the frame and the panels, or something like 'Dynamat'™ adhered to the insides of the panels.

mini wrote:So far, dampening the noises coming from the grinder chamber has been ineffective. I haven't noticed a difference in different types of lids. I'm still thinking about things, though.

Look at the hopper and what it's made of. If it's like mine, it's pretty resonant plastic, shaped like a trombone bell... If it's fulla beans, that should dampen it pretty quick, but empty, you might try finding a canning jar gasket or something to put on the lid, and then the beanbag (the hackey-sak isn't really an optimal example of that idea as much as the old beanbag ashtrays are) trick on the top of the lid.

Psyd wrote:Look at the hopper and what it's made of. If it's like mine, it's pretty resonant plastic, shaped like a trombone bell... If it's fulla beans, that should dampen it pretty quick, but empty, you might try finding a canning jar gasket or something to put on the lid, and then the beanbag (the hackey-sak isn't really an optimal example of that idea as much as the old beanbag ashtrays are) trick on the top of the lid.

I'm actually using a mini-hopper made out of a paper cup, not a Mini hopper.

I tried filling it up all the way with beans, about 4 to 5 inches high, but that didn't help much. I also can get a complete seal with my hand on the top, which I assume has roughly the same sealing/dampening affect as a gasket with (proper) beanbag. This really doesn't seem to do much either. Any other suggestions?

Am I wrong in thinking that my hopper is as quiet as a hopper made out of a more solid material with proper sound dampening? Not to initiate an in depth physics of sound debate, but is my paper cup too porous to contain sound properly?

mini wrote: Not to initiate an in depth physics of sound debate, but is my paper cup too porous to contain sound properly?

No in depth physics required. Sound is moving air. Air moves when paper cup starts to push it around. If the paper cup is moving (feel it) then it's making or transmitting sound.
OTOH, a paper cup filled with beans with your hand over it is probably the least amount of sound you're going to get out of the hopper portion of your grinder without getting into high-tech, high-dollar solutions.

You may be hearing the transfer from the body of the mini, and again, solutions for that start to get costly and change the construction of the grinder. You may be at the noise floor of the grinder.
You know, crushing beans will always make some noise, but a good hybobaric chamber will do away with almost all of it. Cost, about $200K, and it's about the size of a small Airstream trailer. Decibels are weird, the cost of them is also a logarithmic progression, whether you're wanting to create them or suppress them.

Greetings,

Cheap solution = ear plugs.

Cliff