Noisy fan on ampeg micro vr

[scotch]

Justin, you could have the best of both worlds with a long speaker cable and a baffle around the cab

Does record very well, though, doesn’t it?

It sure does!

There's work-arounds, for sure- but for a home studio, convenience and a small footprint are key.

Maybe it's time I built my own 1x10 iso cab with a mic installed inside.

 

[scotch]

WARNING: this post may be 'triggering' for some individuals! Read at your own discretion! ;-)

Well, as detailed in one of my responses above, given my use case and as my unit is well.out if warranty, I decided to mod my Micro VR with a fan defeat switch. I have been using my Micro rig this way as a living room rig and occasionally in my home studio where I mic it up. I've run the amp (on average) for maybe an hour at a time a few times a week for over a month now with zero perceptible problems. Could I be doing unseen/unheard damage? Sure! But, I now have an amp that is 100% more useable for me as I don't use this amp for gigs (although the fan is easily engaged so I could & definitley would use the fan outdoors in the heat or for extended use).

Used a leftover on/off circuit break switch that I salvaged off some panel long ago....

 

[agedhorse]

Thus is why safety standards require testing with a fan failure to insure that if the amp/power supply does fail, it doesn’t produce a shock or fire hazard when it does.

Many of the 60065/62368 safety regulations (and cautions) from the last 30-40 years center around users doing (really) stupid things with their equipment.

In the case of this amp, there won’t be any warnings or perceptions of problems. The failures tend to be instantaneous.

 

[scotch]

I reserve the right to do "stupid" things (really stupid, or just regular stupid) with my equipment. ;-)

I'm accepting the risk on this to adapt the amp so it is, well,... usable for me. We'll see what happens - I have a funny feeling any failures aren't going to be quite as life-threatening or catastrophic as implied.

 

[agedhorse]

I reserve the right to do "stupid" things (really stupid, or just regular stupid) with my equipment. ;-)

I'm accepting the risk on this to adapt the amp so it is, well,... usable for me. We'll see what happens - I have a funny feeling any failures aren't going to be quite as life-threatening or catastrophic as implied.

Absolutely you have the right to do “stupid things” of all styles and levels of “stupid” with your equipment. No argument from me.

Because it’s understood that people will do stupid things, designers are forced to insure that reasonably stupid things won’t hurt you, other people, or create a fire hazard.

You may get lucky, you may not, my warning is to other people who don’t recognize stupid things or haven’t learned those life lessons yet.

 

[Sprudellio]

Just to chime in:
I changed the stock fan to the Noctua couple of months back as well.
Lots of gigging and rehearsals with zero issues so far.
It turned the amp from being too obnoxiously loud to useable in any scenario for me.

 

[12BitSlab]

Thus is why safety standards require testing with a fan failure to insure that if the amp/power supply does fail, it doesn’t produce a shock or fire hazard when it does.

Many of the 60065/62368 safety regulations (and cautions) from the last 30-40 years center around users doing (really) stupid things with their equipment.

In the case of this amp, there won’t be any warnings or perceptions of problems. The failures tend to be instantaneous.

I assume that hardware is like software in that once something is made idiot proof, they invent a bigger idiot. True????

 

[agedhorse]

I assume that hardware is like software in that once something is made idiot proof, they invent a bigger idiot. True????

Seems to be pretty true…

 

[blr2]

The big question to me is why Ampeg haven't addressed this issue. The head has been in production for well over a decade (and still is, I believe). Installing a quieter stock fan is not a rocket science.

 

[beans-on-toast]

The big question to me is why Ampeg haven't addressed this issue. The head has been in production for well over a decade (and still is, I believe). Installing a quieter stock fan is not a rocket science.

It costs more to use a quieter fan. The fans are noisy on most all their amps. With a loud amp, a bit of fan noise isn’t an issue. Playing in a quiet room at a low volume level is a different story. People have raised this issue. It’s complicated. If they upgraded the fan, customers with older revisions would want an upgrade. It would be expensive for a new fan and to have the service centers install it. This wouldn’t raise to a level of a recall, it isn’t a safety issue.

The process would create bad blood. Better to leave it as is.

 

[Sparky Mark]

When I owned one I looked into mounting the fan on rubber inserts/washers, because it's the fan vibrations transmitted to the rear panel that cause most of the noise. Unfortunately however, the assembly is so tightly arranged that it proved impossible for me. At the end of the day, this is an excellent class AB amp for playing live. The fan was a minor annoyance during quiet practice but I could live with it.

 

[agedhorse]

The big question to me is why Ampeg haven't addressed this issue. The head has been in production for well over a decade (and still is, I believe). Installing a quieter stock fan is not a rocket science.

Actually, it is more difficult than it appears.

A cooling fan is part of the critical components that must be tested along with the rest of the amp for international safety certification. All operating temperatures are defined in part by the fan's performance, and the fan itself must have an appropriate 62368 safety certification under the current regulations (IEC 62368-1).

This means that the amp generally must be re-tested by the test lab to insure that the safety critical temperatures remain within the limits of the safety standard and the test report updated. This requires that the test report and certificate be amended after passing, an fairly costly endeavor based on my experience.

If a manufacturer simply changed the fan without follow-up testing and approvals, the safety certification would become invalid.

 

[blr2]

I get it, but if that's the price that must be paid for a faulty engineering (this is a faulty engineering in my book), so be it. This is an amp which main purpose is home practice, recording and small acoustic gigs. The level of fan noise is unsuitable for many of these situations. Shame, because otherwise the head sounds good and looks cool. If it wasn't for the fan issue, I'd have still owned mine. To me, this is a typical example of an otherwise good product ruined by a single engineering error. How much more expensive it would have been to fit it with a quieter fan from the very beginning...

 

[agedhorse]

I get it, but if that's the price that must be paid for a faulty engineering (this is a faulty engineering in my book), so be it. This is an amp which main purpose is home practice, recording and small acoustic gigs. The level of fan noise is unsuitable for many of these situations. Shame, because otherwise the head sounds good and looks cool. If it wasn't for the fan issue, I'd have still owned mine. To me, this is a typical example of an otherwise good product ruined by a single engineering error. How much more expensive it would have been to fit it with a quieter fan from the very beginning...

Depending on what drove the selection of the factory fan, it may have been impossible to pass safety certification with a quieter fan. There are more losses in that MOSFET output stage than a "casual observer" might expect, the hint is that there is a voltage boosted voltage amplifier stage and bias spreader circuit in order to overcome the output stage Vgs offsets.

My hunch is that there is more to this than a simple quieter fan, especially when it needs to pass safety certification. There's always a solution, either through a redesign, growing larger, thermal tracking (harder than it seems to do it right with MOSFET power stages combined with bipolar drivers), etc.

 

[blr2]

Depending on what drove the selection of the factory fan, it may have been impossible to pass safety certification with a quieter fan.

I have a very, very hard time believing that. Look at the computer industry. You have very quiet fans that can move a lot of air. Cooling is critical there too. Better fans are more expensive because they have better bearings that produce less noise at the same diameter and rpm. Also, many people have reported that mounting the fan properly cuts the noise considerably. Perhaps the engineers at Ampeg could have known that...
To me it is just corporate greed, why paying $1-2 more for a better one (plus 0.01-0.02 for four rubber washers), while this will do the job. Shame, because it ruined an otherwise good product.

 

[agedhorse]

I have a very, very hard time believing that. Look at the computer industry. You have very quiet fans that can move a lot of air. Cooling is critical there too. Better fans are more expensive because they have better bearings that produce less noise at the same diameter and rpm. Also, many people have reported that mounting the fan properly cuts the noise considerably. Perhaps the engineers at Ampeg could have known that...
To me it is just corporate greed, why paying $1-2 more for a better one (plus 0.01-0.02 for four rubber washers), while this will do the job. Shame, because it ruined an otherwise good product.

You are making assumptions that IMO are wrong.

It's possible that it's about cost, but its more likely that they needed a certain CFM and a specific static pressure in order to comply with one of the safety regulations, or possibly to keep the amp from failing under certain conditions.

Much of the noise is from the air flow itself, it may have nothing to do with the bearings or the mounting.

 

[blr2]

Much of the noise is from the air flow itself, it may have nothing to do with the bearings or the mounting.

NO, it's not. I had this head for some months, trust me. Even so, if they could not make a relatively low power amp to have a reasonably quiet active cooling, this is FAULTY ENGINEERING. At the same distance, this thing was louder than my air conditioner for crying out loud! This is when using no more than 5-6 W of power in my living room.
I see that you may want to justify the actions of your colleagues at Ampeg, but in this case they failed big time and spoiled a good product.

 

[agedhorse]

NO, it's not. I had this head for some months, trust me. Even so, if they could not make a relatively low power amp to have a reasonably quiet active cooling, this is FAULTY ENGINEERING. At the same distance, this thing was louder than my air conditioner for crying out loud! This is when using no more than 5-6 W of power in my living room.
I see that you may want to justify the actions of your colleagues at Ampeg, but in this case they failed big time and spoiled a good product.

Since already you know more than Ampeg does, why don't you go into the business of designing your own line of amps. It will be an eye opening (and butt puckering) experience. Go show them how it's done

 

[blr2]

Since already you know more than Ampeg does, why don't you go into the business of designing your own line of amps. It will be an eye opening (and butt puckering) experience. Go show them how it's done

That's a faulty reasoning and not very polite. The fact that they screwed the cooling of the Micro VR is undeniable, as witnessed by hundreds of disappointed users, me included. They could and should have done it better, no need for me to do it, although we see many people here fixing Ampeg's stupid mistakes. I elected not to do so, and just got rid of the head, losing money in the process (kept the cab, it's nice).
PS: Besides, I have a PhD in physical chemistry, so I may not be as profane as you may thing, although I don't design amps.

 

[agedhorse]

That's a faulty reasoning and not very polite. The fact that they screwed the cooling of the Micro VR is undeniable, as witnessed by hundreds of disappointed users, me included. They could and should have done it better, no need for me to do it, although we see many people here fixing Ampeg's stupid mistakes. I elected not to do so, and just got rid of the head, losing money in the process (kept the cab, it's nice).
PS: Besides, I have a PhD in physical chemistry, so I may not be as profane as you may thing, although I don't design amps.

I never suggested that you were profane, I suggested that maybe you don't recognize the challenges involved with bringing a product like this to market, and WHY they may have made the choices they did.

The combination of new technology (SMPS) combined with old technology (class AB MOSFET power amp) can be more challenging, especially for a safety approved product.

I'm qualified to recognize the challenges because I am an engineer who does design these products from the ground up, and also walks them through the regulatory process. Ampeg's not nearly as stupid as you assume, but I know you will never believe me on this opinion...