[mike1127]

Been playing with DIY isolation... cheap things like sand, lead shot, and inner tubes.

First tried sticking my CDP into a box of sand (covered with plastic) and putting a bag of lead shot on top. That improved things. (Highs more delicate and greater resolution.)

However, the sand got impractical. The CDP would not stay level.

So I tried floating it on a 16" inner tube, with the bag of lead shot still on top. That seemed to have similar effects. I convinced myself that it had nothing but positive effects through some long comparative listening sessions.

However, as happens too often, now that I'm listening for enjoyment, I notice that pace/rhythm/drive (PRAT) seems messed up. Transients are too soft, and fast lines don't have the necessary drive

Guess I need to try a few more configurations. Maybe get rid of the inner tube. Maybe too much lead shot.

Any ideas welcome.

 

[Markj]

I was looking at some tables and platforms for microscopes and lab lasers. They are the best antivibration devices and they can be used with turntables and cd players. They can be copied at home.

 

[Audiotodd]

What exactly do you mean when you say these designs can be copied at home? What kind of materials are involved?

 

[Lazarus Short]

Try this: take the feet off the CDP, place a slab of granite (custom-cut to size) top and bottom, and support the whole affair on enough sorbothane pods to take the weight of it. If the idea of the quartz particles in the granite being transducers which convert mechanical vibration to electrical energy bothers you, use slate.

 

[mike1127]

Quote:

Originally Posted by Lazarus Short /img/forum/go_quote.gif Try this: take the feet off the CDP, place a slab of granite (custom-cut to size) top and bottom, and support the whole affair on enough sorbothane pods to take the weight of it. If the idea of the quartz particles in the granite being transducers which convert mechanical vibration to electrical energy bothers you, use slate.

I could try that.

But there's something to think about here. Are we trying to isolate the device from external vibration, or are we trying to help it dissipate or damp its internally generated vibration?

When I put immersed my CDP into a box of sand (with a thin sheet of plastic protecting it from the sand), I was doing both at the same time. I really think the box of sand worked well. The problem is that the CDP wouldn't stay level. One or another corner was always sinking into the sand.

The next thing I tried was floating the CDP on an inner tube. The idea here was to isolate it from external vibration, the same way an optics table works. I also put a bag of lead shot on top of it, to aid in damping its own vibration.

Well, during initial listening tests, I thought this was great. The highs took on delicacy and the resolution improved. Tender passages of Mozart were especially musical and compelling.

Satisfied I had improved the system, I sat down to listen for pure enjoyment. And soon I couldn't shake off the impression that PRaT (pace, rhythm and timing) was off. The musicians sounded half asleep. Transients were too soft. Of course this complemented the tender passages, but ruined everything else.

I tried a new thing tonight. I decided to go back to the sand. Sand is great: it accomplishes mass loading of the shelf, external isolation, and internal damping all at the same time. This time I loaded the sand into one-gallon plastic bags and layered them until I had 12 kg of sand on the shelf. Because the sand was in bags, it wouldn't shift around. The CDP will stay level.

Just finished a lengthy listening test, comparing sand to no-sand. Big improvement with sand. Again the highs took on delicacy and resolution. On a poor recording of some brass instruments, they took on a satisfying degree of body. The reverberation time of a big bass drum was extended.

And this time, no problem with PRaT.

I also had the bag of lead shot, probably about 5 kg worth, on the top of the CDP.

EDIT: here are some photos.

Here is 12 kg of sand under the CDP (which consists of two boxes) and about 5 kg of lead shot sitting on top of the CDP:

Rear view:

Also I put a small bag of lead shot on top the Sonett. It improved the bass a lot. (Much deeper extension, better pitch delineation.)

 

[jojo_b2]

@Mike have you read this. Might be worthwhile trying.

Audio Tweaks - Collection of submitted tweaks

 

[mike1127]

Quote:

Originally Posted by Lazarus Short /img/forum/go_quote.gif Try this: take the feet off the CDP, place a slab of granite (custom-cut to size) top and bottom, and support the whole affair on enough sorbothane pods to take the weight of it. If the idea of the quartz particles in the granite being transducers which convert mechanical vibration to electrical energy bothers you, use slate.

I had a thought about this. Taking the feet off the CDP, for a high-end CDP, might not be the best idea, because the designers probably chose the type of feet and their location on the chassis to give good sound.

I wonder if this explains one experience I had. When I tried to "float" my CDP on an inner tube, it was no longer supported on its feet. The PRaT was messed up, making the musicians seem half asleep. Of course, there is a big difference between this and what you suggest, because my "floating" CDP had a chance to develop new chassis resonant modes, which in your idea, a CDP squashed between two heavy rocks is not going to vibrate all that much.

I suspect that sand is a good idea because it's hard for it to "do wrong." It damps internal and external vibrations, mass-loads the shelf, and yet at the same time grounds the equipment sturdily. It may be possible to do better than sand, but it's hard to beat the price! (Especially if you go to beach to get it.)

Report on using sand under my amp, and a bag of lead shot sitting on top. Got these improvements:

1. WAY deeper bass and better pitch delineation, better bass texture (for example ability to separate the bass drum and the bass guitar).
2. More excitement and presence, so it was a subjective increase in volume (even though I didn't touch the volume control).
3. Felt like a better presentation and balance. The distance of instruments and relative balance just "felt" better. Although I don't have a way to compare to the real acoustic space.
4. More midrange beauty.
5. More resolution, ability to separate instruments and separate direct sound from reverberation.
6. Did I mention deeper bass?
   
7. Also deeper bass.
   

 

[Lazarus Short]

I notice that the Naim power supply is on the bottom. Are there any venting holes in the bottom? If so, you need to make sure the bags of sand do not block air flow. I once tried to float an expensive Kinergetics CDP on bubble wrap for isolation, and it soon blew a power supply cap. Don't let that happen to you - Naim is good stuff.

 

[mike1127]

Quote:

Originally Posted by Lazarus Short /img/forum/go_quote.gif I notice that the Naim power supply is on the bottom. Are there any venting holes in the bottom? If so, you need to make sure the bags of sand do not block air flow. I once tried to float an expensive Kinergetics CDP on bubble wrap for isolation, and it soon blew a power supply cap. Don't let that happen to you - Naim is good stuff.

Good question. There are no venting holes in the Flat Cap, anywhere. The chassis is pretty heavy, so I imagine they consider the chassis to be a heat sink.

 

[mike1127]

Update on DIY isolation.

So I did some listening today to compare two configurations:

(1) Shelf loaded with 12 kg of sandbags. CDP sitting on top of that. The sand will damp vibrations in the shelf and to some extent isolate the CDP.

(2) First put down 4 sorbothane feet, then MDF panel on top of that, then the sand bags, then the CDP. The idea is to provide an isolated platform (the MDF panel sitting on compliant feet) which is itself heavy and highly damped.

I thought that #2 might work better, because it provides an extra layer of isolation. However, #1 was preferable.

The highs were the most obvious thing affected. In #2 they were more prominent, detailed, and defined. But there was an irritating quality to them. Switching back to #1, the highs were softened, and smoother in an appealing way. There really was no loss of resolution with #1---I could still hear inner lines and that kind of thing. PRaT seemed more natural with #1.

This is interesting. You would think anything that provides isolation from ambient vibration in the floor would be an improvement. However, some tweaks take an opposite approach, which is to "ground" the equipment. This means "attaching it securely to the ground"---and I'm not sure what that means, actually. Cones and spikes seem to be popular. Perhaps heavy bags of sand are another way of grounding the equipment.