OrganicZed
Roadie
- Messages
- 768
Silent Fan for VHT 2/50/2 !
- Thread starter Eagle
- Start date
OrganicZed
Roadie
- Messages
- 768
I measured the noise with a sound level meter about one foot in front of the amp and these are the results:
Stock Fan (MNB-MAT 3115PS-12T-B30):
Ambient: 40 dB
Low Fan :46 dB
High Fan : 59 dB
New Fan (Orion OA80AP-11-3WB):
Ambient: 39.9 dB
Low Fan: 40.2 dB
High Fan: 42.8 dB
The mod fan at full speed produces less noise than the stock fan on the low fan speed. I'm going to call that an initial success. I haven't done any testing while passing audio signal nor have I let it run for more than a minute or so. I will be sure to report back if I encounter any issues.
Other thoughts:
Based on additional research online, I think the reason that the leads are not labeled to indicate the hot and neutral is that it does not matter for single phase AC fans. The new fan worked the first time I wired it up and it spins the correct direction as indicated by the manufacturer label on the fan body.
I wish I had thought ahead to have the proper size of shrink tubing on hand. I had some larger heat shrink but nothing small enough for this job. I used electrical tape instead.
I probed what the fan speed switch was doing and found that it drops the voltage to 60VAC in low mode (120VAC to the fan in high power mode).
Stock Fan (MNB-MAT 3115PS-12T-B30):
Ambient: 40 dB
Low Fan :46 dB
High Fan : 59 dB
New Fan (Orion OA80AP-11-3WB):
Ambient: 39.9 dB
Low Fan: 40.2 dB
High Fan: 42.8 dB
The mod fan at full speed produces less noise than the stock fan on the low fan speed. I'm going to call that an initial success. I haven't done any testing while passing audio signal nor have I let it run for more than a minute or so. I will be sure to report back if I encounter any issues.
Other thoughts:
Based on additional research online, I think the reason that the leads are not labeled to indicate the hot and neutral is that it does not matter for single phase AC fans. The new fan worked the first time I wired it up and it spins the correct direction as indicated by the manufacturer label on the fan body.
I wish I had thought ahead to have the proper size of shrink tubing on hand. I had some larger heat shrink but nothing small enough for this job. I used electrical tape instead.
I probed what the fan speed switch was doing and found that it drops the voltage to 60VAC in low mode (120VAC to the fan in high power mode).
ctreitzell
Groupie
- Messages
- 57
I'm glad to see you got your new fan installed
What does "ambient" mean here? Is your noise floor at 40dB? Surely not
the fan running with the amp on standby? I'm unsure what you mean
59 dB!?! What are you using for "sound level meter"...and actual dB meter or a phone/ tablet app?
I mean, mine is loud, but it's 48dB on ipad using SPLnFFT app
...hmmm, I just tried and it's 0300 in the morning, extremely quiet and I'm getting 33-45 dBA...that seems off to me from my previous measurements...I need to do some research...and re-check my previous numbers
Last edited:
OrganicZed
Roadie
- Messages
- 768
Ambient is the noise level in the room with nothing turned on.
I am using an inexpensive (approx. $30) decibel meter, not an application on a phone or tablet.
Eagle
Rock Star
- Messages
- 5,145
They are both the same and it doesn’t matter on this . I presume it is because the fan runs AC . I checked it was running the right direction. Please someone correct me if this is incorrect.
GreatGreen
Roadie
- Messages
- 295
40 db is completely normal for standard room ambience. Keep in mind the db scale is exponential. Every additional 10 db means ten times more sound pressure.
60 db is 100 times louder than 40 db.
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ctreitzell
Groupie
- Messages
- 57
it's very quiet at my place (33 dBA is my typical "silent measurement"...now I've taken a reading, I realize that has been the number in my case)
but that is ipad running SPLnFFT...and ipad internal mic...so calibration may well be incorrect
anyway, I will check my VHTs again in the next couple days
because 48dB fan noise is not bad, so my numbers must be off
it is also important where the measurement is taken (distance from source)
but that is ipad running SPLnFFT...and ipad internal mic...so calibration may well be incorrect
anyway, I will check my VHTs again in the next couple days
because 48dB fan noise is not bad, so my numbers must be off
it is also important where the measurement is taken (distance from source)
ctreitzell
Groupie
- Messages
- 57
OK, I checked this morning
my ambient noise floor in my office studio is 33dBA with nothing running
with desktop computer fans is 35
2902 measured about one foot away from the front panel directly in front of the on/off switch
fan low= 55
fan hi= 60-62
my 2902 is on it's side in a 4U SKB with empty U above and below
my ambient noise floor in my office studio is 33dBA with nothing running
with desktop computer fans is 35
2902 measured about one foot away from the front panel directly in front of the on/off switch
fan low= 55
fan hi= 60-62
my 2902 is on it's side in a 4U SKB with empty U above and below
ctreitzell
Groupie
- Messages
- 57
I wonder if my SPLnFFT app got badly calibrated with user error
previously I had found 90 dBA for too loud when playing electric guitar thru amp(s)...and I had measured 75 to be comfortable
last night (early morning), I was playing in the dead of night and hitting peaks around 95dBA which was sounding good to me and could have easily been louder and still within my comfort zone...hmmmm? I know my hearing is getting worse, but not that bad...and the numbers are looking more like what other people post as a comfortable level
previously I had found 90 dBA for too loud when playing electric guitar thru amp(s)...and I had measured 75 to be comfortable
last night (early morning), I was playing in the dead of night and hitting peaks around 95dBA which was sounding good to me and could have easily been louder and still within my comfort zone...hmmmm? I know my hearing is getting worse, but not that bad...and the numbers are looking more like what other people post as a comfortable level
