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PostPosted: Thu Sep 24, 2009 4:41 pm 
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Bottle Rocket

Joined: Thu Sep 24, 2009 4:32 pm
Posts: 8
hello there, ive been a mesa user since more than 15 years now, played triaxis+gforce+50/50 over a syrincs guitar mate up to date but wanted to get down to 3HE in my rack, so i sold the 50/50 and bought a 20/20.

ive read harmony central user reviews, ive read about the deep mod and i trusted into the mesa sound to order it blindly. today it arrived, plugged it in, a bit scooped sound, so i sat down and deep modded it and soundwise im just super happy now - very warm smooth solo sounds, warm clean sounds and all that at very comfortable volumes so i wouldnt wake the neighbours.

now, ONE thing really got me annoyed though - on low volumes the fan is just superloud - it exceeds the fan noise of my 50/50 by far since its one of those small size fans with high rpm. my question is: are there any replacement fans for a less noisy unit or can i eventually shut it down completely if i use the amp on low power (i rarely play beyond 11am knob volume, and especially not now since i stopped playing live a while ago). i didnt dare to shut it down yet, but the unit is cold even after 2 hours playing.


help appreciated, i didnt expect such a loud unit. for small volume recording sessions this poweramp is unbearably loud. first thing my girlfriend said when she entered today to check my new unit: wow, whats that noise?! :(


kind regards,
simon


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PostPosted: Thu Sep 24, 2009 5:52 pm 
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Bottle Rocket

Joined: Thu Sep 24, 2009 4:32 pm
Posts: 8
hmm, alright, i was so fed up with the fan noise that i simply disconnected the fan and played 1hour with open case, since i couldnt enjoy my rack at normal bedroom level at all thanks to the stupid fan. unlike for bigger amps, the 20/20 tubes are not cooled - instead the middle-mounted fan is just there to dissipate heat from the power supplies sitting in the front part into the rear part of the casing.

with low energy consumption like playing on bedroom volume and slightly beyond, i shouldnt expect any overheating. tested it now with open casing and the big fat power supply block gets about hand-warm - probably not a critical temperature at all.

i think for now ill just leave the fan disconnected and for future live applications ill put another switch next to the ground lift which manually adds the fan for higher power consumption applications.

another possible way would be using a thermal diode maybe, but im not too experienced with such things - if anyone got a good readup on such modifications somewhere on the net, feel free to post it.


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PostPosted: Thu Oct 01, 2009 8:40 am 
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Mark I

Joined: Sun Aug 23, 2009 9:56 am
Posts: 21
I've bought a used 20/20 and the I also find the fan pretty noisy Part of it is mechanical noise form an old fan but a lot of it is the airflow itself. So I've ordered a replacement Sunon fan of the same rpm and airflow and another which is about 2dB noisier from the fan itself, but about 20% less airflow.

I'll let you know how I go.

I think a temperature triggered fan is a good idea but don't know how to do it either. Maybe two or three fans would do the trick, more optimally placed, with much less rpm/airflow per fan.

Where is the cooling actually needed? Tubes? PCB the tubes is on? Elsewhere?


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PostPosted: Mon Nov 09, 2009 8:28 pm 
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Mark III

Joined: Fri Oct 30, 2009 9:16 am
Posts: 467
Location: Guam
With a former profession in temp control I've wired ex. fans within my rask to ex. warmer air from the space, very simple. If anyone wants a diagram send me a msg.

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Main Rig:
#6 of 14 '91 PRS
LD Ch. Studio Pre (MkII C+)
RH Ch. Recto Pre
G-Major
50/50
Pair of 2X12's (Swamp Thangs on Closed Back V30's on Ported)
...some other stuff of course


"A ton of tone. Sure it's heavy...it's a ton"


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PostPosted: Tue Nov 10, 2009 3:16 pm 
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Joined: Thu Oct 15, 2009 1:30 pm
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Location: San Francisco Bay Area, CA
I found that my 20/20 got super-hot in the rack, even at moderate volume. I recommend a larger, quieter fan mounted in your rack pointed at the tubes. The tubes will last a LOT longer if you keep them cooler.

I agree about the fan noise - it was awfully loud.

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PostPosted: Mon Dec 21, 2009 7:28 am 
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Mark III

Joined: Fri Oct 30, 2009 9:16 am
Posts: 467
Location: Guam
...or just more volume :twisted:

_________________
Main Rig:
#6 of 14 '91 PRS
LD Ch. Studio Pre (MkII C+)
RH Ch. Recto Pre
G-Major
50/50
Pair of 2X12's (Swamp Thangs on Closed Back V30's on Ported)
...some other stuff of course


"A ton of tone. Sure it's heavy...it's a ton"


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PostPosted: Tue Dec 22, 2009 5:16 am 
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Mark I

Joined: Sun Aug 23, 2009 9:56 am
Posts: 21
OK I swapped the fan out and also tried a lower air flow fan. Turns out the original is the best.

But now I've bought an AxeFX anyway. (Fantastic BTW). It too has a fan....


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PostPosted: Tue Dec 22, 2009 9:24 am 
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Mark III

Joined: Sun Aug 16, 2009 9:44 am
Posts: 347
Location: Melbourne, Australia.
fearless wrote:
OK I swapped the fan out and also tried a lower air flow fan. Turns out the original is the best.

But now I've bought an AxeFX anyway. (Fantastic BTW). It too has a fan....


Don't you still need your power amp for the Ace Fx though?

How close is the Ace to playing a real tube amp?

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Ibanez RG1620


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PostPosted: Wed Dec 23, 2009 7:07 am 
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Mark I

Joined: Sun Aug 23, 2009 9:56 am
Posts: 21
Yep, still need a power amp. Or a full range flat response speaker (FRFR), like a PA speaker. I am using a powered one, so my rig is now simply guitar>AxeFx>PA speaker. So light and easy and stress-free!

The AxeFx produces a whole signal chain all the way through to sims of cabs. I initially went this way becasue of the ability to move the effects chain around and place a separate tube pre-amp anywhere in the signal chain (esp after boost/distortion etc, but before chorus, reverb, delay etc), as well as then smoothing it all out and adding character with the 20/20. But I like its onboard sounds so much that I think I'll just get rid of my pre-amp. As for the 20/20, well I love it, but I think I've got everything it has and so much more in this one box. It feels really organic. And I can choose what to do with poweramps, different types, different amounts of sag, brightness, power tube distortion and so on. Mind boggling.

The FRFR speaker experience is a bit strange. It is like listening to a really good recording of yourself playing, rather than listening to yourself playing. If that makes sense. I think it probably just takes some getting used to. I haven't tried it cranked in a big space yet as I've only just got it and playyed maybe 4 hours on it at home. So I'm in the honeymoon period, but so far, so good...


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PostPosted: Tue Nov 23, 2010 1:45 pm 
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Bottle Rocket

Joined: Thu Sep 24, 2009 4:32 pm
Posts: 8
alright, i havent been here for a long time, but after some months of playing regularly in the practice room i brought my rack back home again and IMMEDIATELY got fed up with the mesa 20/20 4cm fan noise again. really, its aweful!

aanyway, i started to google again and all i found about annoying fan noise were basically my own complaints in a german boogie forum and here, so i decided that something finally had to happen.

obviously, the small 4cm fan is supposed to drag air through the transformators over the capacitors to finally ease the heat from the tubes via small air vents at the backside of the case. i had basically 4 options:

1.) let the small fan run at low speeds
2.) buy a replacement 4x4cm fan which is hopefully more silent
3.) switch it off completely and put 2 12x12cm fans at the backside of my 3HE rack
4.) find another solution

i tried 1.) first, but it seemed to run too hot when built into the rack, i didnt believe in 2.) since a small fan at high RPMs will always be annoying and audible, so basically i was left with 3.) or something else. i wasnt sure about 2 12cm fans at the back of my rack - it wouldve helped the tubes of the triaxis as well, but i wasnt sure about the cooling of the transformators in the 20/20, so i finally decided to go for 4.). in my case i found a reasonable spot for an 8x8cm fan in the 20/20 casing, drilled a big whole for it, checked for silent fans from the pc market which were guaranteed to run at the 5V power supply of the original fan. this is only possible, since the power amp was always the lowest of my 3 rack units and my rack leaves around 1cm space underneath the 20/20 - enough air for the fan. stuffed it all together and what can i say: wow, finally i like this damn noisy unit!

the be quiet USC 8x8cm fan is really absolutely inaudible at the 5V supply. the cooling is somewhat weaker than the cooling of the high RPM original fan, but strong enough to give me a comfortable feeling about the whole thing - eventually higher voltage can be found somewhere in the 20/20 (im no real expert in electronics, i just checked power demands of the fans and used the old supply cables for the new fan). the flow principle is somewhat diffrent now, since air is sucked in from the lower side of the case, pushed out at the sides/front and the original 4x4cm fan whole into the backmost parts of the case. overall the stream into the backmost parts of the case is weaker than with the weirdly placed original fan, but i think its working out fairly well. the unit is cold in the first part of the case, its handwarm in the middle section and it becomes hot where the tubes are. overall not much diffrent from the original setup.

made some pictures, hope you like it. :)



Image

Image

Image

Image

Image

Image


Last edited by whitepony on Tue Nov 23, 2010 5:46 pm, edited 1 time in total.

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PostPosted: Tue Nov 23, 2010 2:40 pm 
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Bottle Rocket

Joined: Thu Sep 24, 2009 4:32 pm
Posts: 8
incase anyone knows where i can grab 7V/12V inside the 20/20 without doing any harm, please speak up. the silent fan is really silent, even at 12V, so i'd like to increase the air flow as much as possible before the fan becomes actually audible over the 50hz hum of the transformators to keep everything as cool as possible. thinking about testing those small voltage step up circuits, but if i get 7V or 12V easier somewhere inside the unit poke me. ;)


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PostPosted: Tue Nov 23, 2010 6:09 pm 
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Mark I

Joined: Sun Aug 23, 2009 9:56 am
Posts: 21
Nice work.

I am pretty sure there is a schematic on this forum somewhere for grabbing the extra voltage.


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PostPosted: Fri Nov 26, 2010 11:50 am 
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Bottle Rocket

Joined: Sat May 28, 2005 12:49 pm
Posts: 13
I put a $2 switch mounted in the front of the 20-20 to turn the fan off/on when recording. Turns out that I always leave it in the off position, and I never have a problem. Now, this is a studio setup and I never use the 20-20 past 10 o'clock so this might not apply if you play louder, but then the fan noise shouldn't be as much of a problem.
I wish Mesa made a 5-5 amp in addition to the 20-20...


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PostPosted: Fri Nov 26, 2010 12:40 pm 
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Bottle Rocket

Joined: Thu Sep 24, 2009 4:32 pm
Posts: 8
small update: i put a 5V-> 9V DC DC converter (edit for the tech guys: http://octopart.com/nmg0509sc-murata-7992377) in front of the fan by now, since the middle section + tubes are really getting hot. i couldnt even touch the tube area after 1 hour of playing at 9am volume settings. i tested several voltages, 12V makes the fan audiable again, 9V seems the highest voltage where the fan is still basically inaudible (about 1500 RPM). the whole unit and in fact the whole rack benefits from increased cooling cause of the sidevents of the 20/20 where i can feel a noticeable flow of air into the back of the rack now.

and to the guy above me: without fan the unit definitely becomes SUPERhot, especially when built into a rack (i was trying without fan and with original fan at recuced voltages - no chance heatwise imo).

id be the firts buyer of a 2x 5watt unit. ^^


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PostPosted: Thu Aug 23, 2012 4:14 pm 
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Bottle Rocket
User avatar

Joined: Wed Mar 09, 2011 2:23 pm
Posts: 9
Hi,

I too have fitted my mesa 20/20 with fans after being inspired by your pictures. I was experiencing noise from the 5v power supply in the boogie when using it to power my fans. So i started to use a external DC supply to power the in the boogie whch seemed to help.

If some one could explain how to atttach a image i could post pictures.

However the bottom line is i am still experiencing slight noise for some reason only on one channel of the boogie ??

Cheers Dan


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