Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Yosser on May 24, 2026, 12:38:22 pm

Title: Marshall dual monobloc EL34 50/50 - Cooling fan too noisy
Post by: Yosser on May 24, 2026, 12:38:22 pm
Has anybody replaced the fan in this amplifier with a quieter cooling fan, if so what make and model did you use?
Title: Re: Marshall dual monobloc EL34 50/50 - Cooling fan too noisy
Post by: nandrewjackson on May 24, 2026, 04:34:49 pm
Do a search for the mesa boogie cooling fan used in several models.
Title: Re: Marshall dual monobloc EL34 50/50 - Cooling fan too noisy
Post by: Yosser on May 25, 2026, 08:32:15 am
The model of fan is Sunon kd2408ptS1 24vdc 1.6w 40cfm 33db  P/N 13.A.GN

No longer available

https://uk.rs-online.com/web/p/axial-fans/1118358?msockid=07ae167ec7b0634d0bf30003c6a562ce

I would be looking for an equivalent but noiseless if possible.
Title: Re: Marshall dual monobloc EL34 50/50 - Cooling fan too noisy
Post by: acheld on May 25, 2026, 09:41:04 am
I've used several different computer cooling fans w/o difficulty.  They are pretty quiet.  Many of them come with a variety of inline resistors to limit speed, but it is easy to dial in your desired speed as needed.   
Title: Re: Marshall dual monobloc EL34 50/50 - Cooling fan too noisy
Post by: Rontone on May 25, 2026, 09:47:40 am
I was just going to say computer fans, but if your in the UK and ordering from RS check out EBM Papst fans,

I used to work at a Power Amp company and that's what we stocked, they were pretty good, and very quiet

Check them out on RS versus your Sunon for airflow and dB ratings, their about a similar price too, just a little more
Title: Re: Marshall dual monobloc EL34 50/50 - Cooling fan too noisy
Post by: Yosser on May 25, 2026, 12:25:44 pm
I was just going to say computer fans, but if your in the UK and ordering from RS check out EBM Papst fans,

I used to work at a Power Amp company and that's what we stocked, they were pretty good, and very quiet

Check them out on RS versus your Sunon for airflow and dB ratings, their about a similar price too, just a little more

I had a look a them before and the db rating compared to the Sunon, I couldn't ascertain whether 30db or (33db in the sunon) is actually quiet loud or not.
I know the one in the marshall amp is loud to the point that it may be a malfunction and as I am considering selling the amplifier it's a bit of a concern.
You would not notice it at band volume levels but it could be a nuisance in a recording situation.
I had considered using it as a stereo playback amplifier but that fan noise is a no no.
Title: Re: Marshall dual monobloc EL34 50/50 - Cooling fan too noisy
Post by: Rontone on May 25, 2026, 12:44:28 pm
If its really that loud then maybe it is getting a bit tired and rattling like my PC at the moment!

30dB is around the normal level for most of those sizes of fans I can imagine, seems that way when I'm looking at PC fans

I can recommend Noctua branded fans too, unsure if they come in 24V though, although you could alter that I suppose...

But if you are thinking of selling it then just something good and branded and reliable will do, the standard Sunons from RS are around £10 each