Silent Fan for VHT 2/50/2 !

@Eagle how did you determine which lead to connect to the hot lead and which to connect to the neutral? The fan leads don’t appear to be labeled on my replacement fan and searching on google has been unproductive. Thanks!
 
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).
 
OrganicZed said:
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).
Click to expand...
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:
ctreitzell said:
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
Click to expand...
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.
 
OrganicZed said:
@Eagle how did you determine which lead to connect to the hot lead and which to connect to the neutral? The fan leads don’t appear to be labeled on my replacement fan and searching on google has been unproductive. Thanks!
Click to expand...
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.
 
ctreitzell said:
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
Click to expand...

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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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)
 
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
 
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
 
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Huge difference, I should have changed the fan long before !!!

A new tubeset from Tube Amp Doctor has been ordered as well, and should arrive in a few days.

It's ironic (and probably typical) how I am coming back to tubes and cab, after a 10+ years excursion in digital and modelling. ""FRFR"" sounds like a toy in comparison.

The plan though is to keep an hybrid setup, with a digital front end for amps and FX. It feels like the best of both world at the moment.
 
I use mine with an X88 ir and an Axe 3.
I have used it hybrid with axe fx and regular cabs and even with "FRFR" cabs. The 2/50/2 is pretty neutral and I was happy with this. ATM I have it with the X88ir running irs in to the VHT and then two Celestion F12x200 equipped cabs.
IMG_4130.jpeg
 
Last edited:
Melodioso said:
That's an amazing setup Eagle ! It must sound glorious...

Congrats (y)
Click to expand...
It sounds even better when I hook up a 4x12 to the VHT for analog dry only. Then use the Axe as fx only and amplify the wet with a Matrix gt1000 with the F12x200 cabs as wet only.
 
Eagle said:
It sounds even better when I hook up a 4x12 to the VHT for analog dry only. Then use the Axe as fx only and amplify the wet with a Matrix gt1000 with the F12x200 cabs as wet only.
Click to expand...
yep, WDW is THE way

I use 2902 for the wets

still haven't replaced the fans, tho...needs doing

thanks for starting this thread!
 
Melodioso said:
Yes, the fuse on the B channel blew up when I switched to class A.

Ordered this set: https://www.tubeampdoctor.com/en/tubeset-for-vht-fryette-2/50/2-power-amp
Click to expand...
I used the term "blew up" with Fryette support at the other place for the V1 12AX7 in my 2562 A Channel and was told off...cuz "blew up" sounds like there was some shattering of glass or somesuch...I feel it is a typical term to describe a failed electrical component with a power rating...wtf do I know

My 2562 was fully re-tubed with JJs (unfortunately) by the previous owner...and still I have had issues with 12AX7 fails in that V1 socket in chnlA. Support said the JJs were typically not the best choice for that amp. I mostly run it mono, so it's not a big deal...support blamed the tubs I had in the socket
 
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