Silent cooling fans (Hartke etc)

[P. Aaron]

Have a LH1000 and can't hear the fan at all. Have to check closely at rear of unit to tell it's running. It's only a few months old so maybe they changed them?

Ditto here. Have had my LH1000 since 2007-08.

Nice amp. Pounding guitar players into submission, one gig at a time.

 

[avvie]

I know this is an old thread, but thought I'd post my solution. I too had issues with the fan and researching around on the net I found that you can easily replace the fan with a quieter one. I used Invalid Link Removed which only cost $8.74 and replaced the existing one. With the new one I barely know it's even on now in my quiet room.

Did this yesterday, awesome solution, many thanks!

 

[joenoone]

Did this yesterday, awesome solution, many thanks!

Yea, fixing that made me go from hating the amp to loving it again...

 

[pbass2go]

Pounding guitar players into submission, one gig at a time.

Awesome line...

I just bought a used 3500 that sounds great but the fan is loud. Going to look into one of these fans

Love the KC-135A reference. I worked B52-G's and always laughed at how the four engines on the tanker were louder than the eight on the BUFF!

Rock On!

 

[fnordlyone]

Yea, fixing that made me go from hating the amp to loving it again...

I think that the stock fans are built for the stage with the amp burning hot every night at their max. Otherwise, they would get a crap rep and be returned by live musicians. All that air flow isn't necessary in the home studio environs. Don't get rid of a nice amp over its fan noise… upgrade is so cheap and easy.

fnord!

 

[joenoone]

I think that the stock fans are built for the stage with the amp burning hot every night at their max. Otherwise, they would get a crap rep and be returned by live musicians. All that air flow isn't necessary in the home studio environs. Don't get rid of a nice amp over its fan noise… upgrade is so cheap and easy.

fnord!

Actually the one I list/used has more airflow then the factory one and is quieter. I researched the specs for the stock one before ordering a replacement as I wanted to be sure it got at least as much airflow.

 

[Camaro69]

Subd

 

[fnordlyone]

Actually the one I list/used has more airflow then the factory one and is quieter. I researched the specs for the stock one before ordering a replacement as I wanted to be sure it got at least as much airflow.

I lost a little airflow when I switched my qsc rmx 1450's original fan, but it (Invalid Link Removed) never has run hot after the switch.

fnord!

 

[Stefan Verbeeck]

I used to go with two fan idea. I placed two 12V ones in series. One was the replaced 8cm one and the other a small 4cm model in front of the heatsink. Gives me an air-in/air-out setup. However they seem to be REALLY quiet so this might not be the best plan for hot regions.

 

[agedhorse]

I would like to make a couple of suggestions here, as I have seen a few amps come in for repairs that had been inappropriately modified with "super quiet" fans that caused unexpected problems.

Forst of all, it's critical to understand that fans, especially in the computer industry, are not all rated to the same performance standards. For example, noise levels can be measured at different distances, or with different finger guards and get entirely different numbers.

Second, fans operating under different static pressures are designed with different blade pitches and profiles. To get the quietest operation, it's important to match the fan performance curves to the actual static pressures and speeds involved.

Third, amp designers generally calculate the necessary CFM at the actual operating static pressure that the fan will see. CFM varies by static pressure and fan blade design, so you can have 2 fans that sat 35CFM but one will be say 35CFM at .1" WC and only 10CFM at say .25" WC whereas the other may be 35CFM at .1" WC and 29CFM at .25"WC. If the amp design has a .25" WC static pressure but the first fan was installed, there would be a serious reduction in flow under operating conditions.

Fourth, with variable speed fan circuits, the control circuit is designed around a particular fan performance curve. Varying from this curve will affect the cooling performance in practice.

Fifth, changing a fan will void most manufacturer's warranties.

 

[Stefan Verbeeck]

@agedhorse

Good explanation!
After reading your post I should add the following disclaimer to my mod:
I changed mine to super quiet ones with the idea to never use it for a long period and at normal room level.
I can still feel a steady flow of hot air coming from the back.
And lastly mine has no temp control at all, so both run at max all the time.

Cheers

 

[fnordlyone]

Yeah, I run my old qsc as my music room power amp, not a hot stage environment. The original fan sounded like a vacuum cleaner. It was designed to be in a rack on stage and had a super robust fan… I bought my amp used; so, the warranty issue wasn't an issue. My qscrmx1450 hardly ever gets warm before or after my upgrade, but I researched a long time and got to know the tech lingo for what was safe while getting the noise down. I think any DIY'er would/should do the same before burning up the amp. Newer fans can deliver more airflow for a lot less noise than the stock fans on some old amps.
fnord!

 

[Artman]

I use my 3500 Mosfet with upright bass mostly, in a band that has lots of very quiet sections to our music. We usually play in smaller rooms to an intently listening audience, so fan noise has been an annoyance for me for some time now.

I just put in a Sanyo Denki fan p/n 9S0824L4011 that I got from Mouser (p/n 978-9S0824L4011)

Direct replacement, 24V, 23.5cfm, claimed 16dBA

I has a yellow temperature control lead but that can be snipped and tipped with some heat shrink and ignored. Dropped in with no physical mods necessary and it is very quiet compared to the stock fan in mine (the aforementioned super-noisy Fonsan).

Sometimes a fan can transfer noise to the amp enclosure so putting thin foam rubber tape between the fan and the case can help in those instances.

I also was noticing a lot of buzz from the transformer when I turned the amp on, so I put a layer of foam tape on between it and the top panel to damp it out.

Old thread, I know. Please don't flog me. ;-)
I just purchased a used 3500 head from a guy via Reverb.com. Just after pulling the trigger, I remembered how noisy that fan had been on my last two 3500's about 22 years ago. Then I found this thread! Ordered the very same fan above from Mouser. Installed it today and WOW! So MUCH QUIETER! The old hand next to the fan test appears to indicate the same or possibly slightly more airflow. This amp already had two strips of rubber tape on top of the transformer, so no buzzy-rattly noises there. Installed a new pre-amp tube and vacuumed everything out while I was in there.
Totally satisfied! Thanks for the pointers guys!