SD Powerstage 170 fan issue?

DaveMon

Just received a replacement amp as my first one had the fan spinning all the time. 
However the replacement is doing the same thing. 

According to SD support the fan should only spin once at power on and then shut off until the unit needs cooling. 

I’ve sent another question into SD support to see if the fan behaviour has been changed so that it is spinning constantly on the current batch of amps. 

Or is it that there is a faulty batch and I’ve received another faulty one?
The serial numbers are 4 digits different on the 2 amps. 

If if anyone has a PowerStage 170 can you let me know how your fan operates on the amp?

ecc83

Ha! Many years ago Sony brought out a range of "Micro Hifi" and the amp, punchy wee thing, 50Wpch iirc, had a thermostatic fan. The customer complained that it was noisy when it kicked in and so a phone call to Sony elicited a mod kit.

I fitted it in the punter's bedroom and the "mod" was that now the fan ran ALL the time! Needless to say, we got the kit back and lost the sale.

Many electronics designers view cooling fans as a design failure, often prompted by the bean counters not being prepared to stump up for big enough heat sinks or enough OP devices. Maybe back in the earlier design stage that fan should have been controlled? THEN they had burn outs!

I spent a good 3 weeks taking temperature measurement from the heat sink of an amp's power controller just to make sure it was getting the right cooling..SANS fan!

Dave.

DaveMon

That is one thought I had @ecc83 that they’ve had to adjust the fan profile to prevent component damage. 
I’ve sent another message to SD support and to their UK distributor to see if they will confirm it either way. Fan adjustment or faulty batch. 

It it does sound pretty good. 
And the fan is quiet and unobtrusive at the moment. 

DaveMon

Currently contemplating testing it against an Orange pedal baby, which as far as I know doesn’t have a fan. 

ICBM

ecc83 said:

Many electronics designers view cooling fans as a design failure, often prompted by the bean counters not being prepared to stump up for big enough heat sinks or enough OP devices.

This. At the power levels in guitar amps and even many bass amps, there should be no need for fan cooling if the gear is properly designed in the first place, although it gets harder to avoid with bass amps above about 300W.

Fans can fail and which will cause (usually expensive) failure of the rest of the kit as well.

Clecko

I bought one of these a few weeks ago and the fan - though quiet - runs all the time. Would be very interested to hear what SD say and I can check the S/N if helpful?

Could I ask a massive favour? When SD come back to you, would you mind letting me know by DM so that I can recheck the thread? I'm not on here that much and the topics move fast!

fretmeister

I hate fans that can be heard at TV volumes.

I don't mind if they wind up a bit when cranked - as long as they can't be heard above the louder playing, bur for low level playing or late nights / recording etc it's a nightmare.

I had the wonderful Mesa Prodigy 4:88 once. 265W all valve.

Sounded amazing (as it should have done for the money) - but the fan was stupid. Looked to be a 4 inch item, it was loud and whiny. Made it impossible to use at TV listening levels.

I thought about having the fan replaced for a "silent" version but in the end I traded it for a Demeter 800W amp that was fanless - never overheated either - just properly designed in the first place.

I don't get the obsession with making the case as small as possible - it just causes heating issues. And then for many small amps the design means they can't be racked either.

Just stick them in 1 or 2u rack sizes with proper cooling. Maybe have a fan for when the amp is working in the top third of the output - at that volume there will be a noisy drummer anyway. Otherwise let them run silently as they should.

I want to hear the notes - not the fan.

ICBM

Fan noise is largely due to cheap fans. The Ampeg Micro VR I have was also unusable at home volume - ridiculous, given that it's really a toy best suited to your sitting room, and not a real gigging amp - and that was on the slowest fan speed. On the fastest it was like an air-raid siren and annoying even at band volume when everyone stopped playing...

I replaced it with a low-noise Papst fan, and the fastest speed was then about the same as the slowest had been before, and the slowest was inaudible even at late-night bedroom volume - so much so that when I first turned the amp on I thought it wasn't working at all. Admittedly this fan cost £15, and the original was probably worth about a tenth of that.

ecc83

Yes, fans can be cheap and noisy or pricey and quieter but they all suffer from the same problem..Muck.

Even without fan sucking or blowing an amp will develop a "crust" on every exposed surface. The solution is of course to fit a fan and filter the air going in but you then rely on the punter cleaning/changing the filter!

Most fans on most of the gear I have seen do not have filters so they just clag up themselves. Even a mm of muck on the blades has a drastic effect on a fan's efficiency but then they rarely get cleaned until they gum up completely and something blows.

Dave.

ICBM

ecc83 said:

Yes, fans can be cheap and noisy or pricey and quieter but they all suffer from the same problem..Muck.

Even without fan sucking or blowing an amp will develop a "crust" on every exposed surface. The solution is of course to fit a fan and filter the air going in but you then rely on the punter cleaning/changing the filter!

Most fans on most of the gear I have seen do not have filters so they just clag up themselves. Even a mm of muck on the blades has a drastic effect on a fan's efficiency but then they rarely get cleaned until they gum up completely and something blows.

Or worse. I should probably warn you that the following picture is not pleasant to look at - but it's a perfect illustration of the risks of fan cooling coupled with lack of maintenance.

It's a QSC PA power amp which had been installed in a club for many years before the smoking ban. It had essentially been operating as an air cleaner for the club...

DaveMon

Had a response from the distributor and they are forwarding my query over to the SD technical department. I’ll post the response soon as I get an answer.
@Clecko I will dm you the details of the 2 units I’ve had and when SD get back to me.

I’ve seen the insides of PCs that look very similar to that amp @ICBM and even with filters on the intake fans it still doesn’t stop the muck getting in. Just means it’s a very fine layer of dust that still coats every surface of the components. 

Going to to organise a return again for this second unit, but I won’t be requesting another replacement. 
I’m just not happy with a constantly spinning fan waiting to clog up in a year or 2. 

ecc83

"I’ve seen the insides of PCs that look very similar to that amp @ICBM and even with filters on the intake fans it still doesn’t stop the muck getting in. Just means it’s a very fine layer of dust that still coats every surface of the components. "

Yes Dave M but often that is because the filters have not been changed/cleaned often enought and the dust is being "pulled thru" the filter!

Fans have their place where there is proper, scheduled maintance. Comms room racks often have multiple top fans (built a few) and filters at the bottom 2U space. There would almost certainy also be some thermal management software in the system to alert the IT bods when things were getting too warm.

On another tack. I wonder how many Dysons have been "WEE'ed for want of a clean filter?!

Dave.

DaveMon

Just had confirmation through the distributor from Seymour Duncan, that the fan on the PS170 is now set to run all the time.

However on the PS700 the fan is still temperature controlled and will only spin when cooling is required.

Wazmeister

Bumping this old thread.

Ive just purchased a PS 200, and the fan is always on, AND emits considerable noise…

Danny1969

These things are using Icepower modules ... a generic SMPS and class D digital amp on one compact PCB which also has an auxiliary power supply for a pre amp and a power supply header for a PC type fan. It's a very complex design that allows other manufacturers to get powered products straight to market. I've got a couple myself. 
These things are great for powering home cinema systems, monitor speakers and such but might not have been designed living in such a small box. Personally if I owned one I would want the fan on constantly. 

Hydra

Sold a Mesa Mini Mk5:25 because the stupid fan made it unuseable at home. 

Same thing with a Marshall 20:20 power amp.  

The Blackstar St James has one… doesn’t bode well.