Shopsmith Forums

dusty wrote:Are all of these facts relevant if all one is doing is collecting readings for comparative analysis.

If I take a reading from 5 feet away from the headstock before rebuild and I then take another reading from the same location after rebuilt and the readings are the same - I can conclude that I did nothing to reduce noise level.

Am I reading you correct, 8iowa?

I realize that the shop is an acoustic chamber and that if I take readings from different locations they are likely to be different. All that I am attempting to do (for my own curiosity) is determine if a rebuild reduces the noise level significantly or not.

I believe that your logic is sound as to determining if the rebuild made it quieter. I do suspect though that it may be possible to quiet one pitch while increasing another. Maybe replacing a growl with a whine or something like that?
You might also record it running before and after with identical circumstances and listen to both after to see if it is quieter.
Interesting...

Dusty:

Due to all the echos, taking readings in your shop is not a good place for comparative readings. If you want meaningful data, take the headstock outside to as large of an open space as possible, and as far away from any reflective surfaces as you can get. Pick a real quiet time of day, like a Sunday morning, in order to minimize background noise, and carefully take readings all 360 degrees around the headstock at the same distance. I suggest three feet, as this is kind of a standard. Then average the readings.

I've been tempted to purchase a sound level meter and make some of these tests as my conditions here in the middle of the Hiawatha National Forest are very anecohic and the background noise level is extremely low.

8iowa wrote:Dusty:

Due to all the echos, taking readings in your shop is not a good place for comparative readings. If you want meaningful data, take the headstock outside to as large of an open space as possible, and as far away from any reflective surfaces as you can get. Pick a real quiet time of day, like a Sunday morning, in order to minimize background noise, and carefully take readings all 360 degrees around the headstock at the same distance. I suggest three feet, as this is kind of a standard. Then average the readings.

I've been tempted to purchase a sound level meter and make some of these tests as my conditions here in the middle of the Hiawatha National Forest are very anecohic and the background noise level is extremely low.

I could probably find a somewhat quiet place outside the shop to take these measurements but the quail and cactus wrens will undoubtedly produce some spikes in the readings. If I invade their territory the quail just leave but the cactus wren become hostile (especially now because it is nesting season).

first things first - you certainly don't want to interfere with momma bird.

When I finally do this pending rebuild it will be interesting to see what the noise level differences are. Right now, without doing anything to the Mark V, the noise readings would meet the acceptance criteria established in this thread.

[ATTACH]8759[/ATTACH] [ATTACH]8760[/ATTACH]

Low Speed on the left (70dB Range) and High Speed on the right (80 dB range)

My machine generates a little bit more noise at high speed than Jacob Anderson says is acceptable at low speed BUT my readings are with a 5 foot separation between the headstock and the noise meter. It Jacob's DVD he is holding the noise meter much nearer the headstock and the headstock is setting on a padded bench top.

If noise level was the only factor, I probably should not bother with changing bearings throughout.

I just had a hearing test done as I was having issues with my right ear hearing and the results were terrible. I am 46 and I have the hearing of a much older person. I was asked if I listen to loud music a lot and I told the doc not anymore and it has been many years since i did but i guess the damage was already done. I have very poor high frequency hearing and he said as long as I watch it I should be alright but if i continue to subject my ears to damaging levels of sound I would be sorry.

So I have been very good about using ear protection the last couple of months and will continue to do so to keep what little i have left functioning. So if you are working in an environment where the sound level is very high please do yourself a favor and wear the hearing protection it will pay in the long run.

I noticed you were NOT using the A weighting as recommended by 8iowa. Does it make a difference in the readings?

JPG40504 wrote:I noticed you were NOT using the A weighting as recommended by 8iowa. Does it make a difference in the readings?

Using A-weighting rather than C-weighting would certainly provide some variations in the readings.

When using A-weighting, this meter responds to a frequency range from 500 Hz to 10,000 Hz. This is basically the entire range of human hearing.

The C-weighting response curve is from 32 Hz to 8,000 Hz and is nearly uniform over the entire range. This provides a good indication of overall sound levels.

Is one mode more appropriate than the other for this specific test purpose? I don't know.

The manual states: "Use A-weighting for voice recordings, or C-weighting for full range musical material". The sweet sound of a smooth running Mark V is truly "music to my ears", and no one was talking during this test so I used C-weighting.

If anyone needs to know what the readings would be in a different set up those results can be had. Just ask.