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Loud Fans


cord.scott
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On 01/09/2020 at 19:15, Dan Dare said:

I have an AG700 and it isn't loud at all. You can hear it faintly when you're standing close to it and no music is playing, but it isn't intrusive. I wonder if there's an issue with yours.

I've owned 2 of these amps (AG700) both had the same fan noise. It kicks on after few minutes of playing. Most of the time I'm using it as  a DI for silent practice and it is annoying. I'm comparing it to my mesa d800+ which is dead quiet and its fans run the whole time. Just don't understand why if there is a quieter option, a manufacturer would not use it.

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On 01/09/2020 at 17:51, agedhorse said:

Be careful swapping fans to be sure the characteristics match what the designer intended. the is ESPECIALLY true on amps that have variable speed fan control circuitry. These circuits and the fans must track for the cooling to be the same. 

I agree and its probably beyond me to do it. I'm comparing it to your amp, the d800+, which is my main amp now. The d800+ is very quiet. 

I own the d800+ DI too, so perhaps I'm making an issue out of nothing, but was kinda just wondering. 

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7 hours ago, pineweasel said:

I have a Tone Hammer which is similar. The noticeably loud fan comes on after 20 mins or so then never turns off, even if you're just using the DI. Aguilar told me it was normal, and it's not a problem for gigs so I live with it, but it's annoying

Yeah I'm not saying there is a manufacturing defect, that it operates any other way than as designed. I'm just saying the fans should and could be quieter. 

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12 hours ago, cord.scott said:

I agree and its probably beyond me to do it. I'm comparing it to your amp, the d800+, which is my main amp now. The d800+ is very quiet. 

I own the d800+ DI too, so perhaps I'm making an issue out of nothing, but was kinda just wondering. 

The fan on the Subway amps (and other amps that I have designed in the past) are quiet by design. It's not something that can really be retrofitted AND still have acceptable performance under hot ambient conditions, 

As an example, it's not uncommon to reach 100 degrees F in my area so I typically design to somewhere around 105 degrees F as the high ambient temperature condition. At these temperatures, I doubt anybody would want to either play bass or listen to bass or a band or much of anything IME.

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2 hours ago, agedhorse said:

The fan on the Subway amps (and other amps that I have designed in the past) are quiet by design. It's not something that can really be retrofitted AND still have acceptable performance under hot ambient conditions, 

As an example, it's not uncommon to reach 100 degrees F in my area so I typically design to somewhere around 105 degrees F as the high ambient temperature condition. At these temperatures, I doubt anybody would want to either play bass or listen to bass or a band or much of anything IME.

Sure I get all that and agree.

Maybe my logic is too simple. I know the mesa amp and the aguilar are based around the same power module. Knowing that you made the mesa work with quiet fans it seems reasonable to assume other manufacturers could do the same thing. I'm sure there are several variable here. Where is the flaw in my thinking?

If there is a choice of a quiet fan to do the job vs a louder one, I don't see the reason that would lead to a designer choosing the louder one.

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15 minutes ago, cord.scott said:

Sure I get all that and agree.

Maybe my logic is too simple. I know the mesa amp and the aguilar are based around the same power module. Knowing that you made the mesa work with quiet fans it seems reasonable to assume other manufacturers could do the same thing. I'm sure there are several variable here. Where is the flaw in my thinking?

If there is a choice of a quiet fan to do the job vs a louder one, I don't see the reason that would lead to a designer choosing the louder one.

It is indeed the designer's choice. It's not just the fan, but the aerodynamics of the air flow, the ratio of laminar flow to turbulent flow, and how the heat is removed from the devices and into the atmosphere. Using the same power module and even the same fan, it's possible to have very different noise levels depending on the choice of the designer and the designer's experience in the area of thermodynamics. I actually am the "inventor of record" on a US patent for the management of thermal loads and peak current management in class D amplifiers, so this is obviously not something that I take as casually as others might.

There are many ways to skin this cat, some are quite elegant and some quite messy. 

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Given that you only notice the noise when you use it as a DI for quiet or silent practice, why not use something designed/intended more for that purpose and keep the AG for live playing? I use a small mixer, a DI box and headphones for silent practice. If I wish to play along with something, I can route music through it and blend the bass with it. Works fine.

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38 minutes ago, Dan Dare said:

Given that you only notice the noise when you use it as a DI for quiet or silent practice, why not use something designed/intended more for that purpose and keep the AG for live playing? I use a small mixer, a DI box and headphones for silent practice. If I wish to play along with something, I can route music through it and blend the bass with it. Works fine.

Because we like to use the gear we own?

I've had amps where I couldn't use them when supporting woodwind instruments because the fan noise was obvious in the room. (Including a Mesa, it has to be said).

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On 10/09/2020 at 06:14, Dan Dare said:

Given that you only notice the noise when you use it as a DI for quiet or silent practice, why not use something designed/intended more for that purpose and keep the AG for live playing? I use a small mixer, a DI box and headphones for silent practice. If I wish to play along with something, I can route music through it and blend the bass with it. Works fine.

Because it has an amazing sounding preamp that I love. I run its di through a small mixer and blend as well.i can't stand bad tone and think all basses, yes literally all basses, sound awful without a good preamp heading in to the console. I dont like the pure sound of any bass I've ever owned. Yes, I'm picky about tone.

Because of the fan noise it gets used less than my other amps.

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I've returned an Aguilar TH500 for the same issue. Kicked in after 10-15 minutes of low volume usage, at maximum speed when the amp was still cool to the touch. Even worse is that you can hear a pop sent to the speaker cab when it kicks in.

On my Orange Terror Bass, I've replaced the fan with a much quieter one - much less air flow than the original, I knew I was taking a risk in doing so but it turned out just fine. It has a massive heatsink and more air flow than most amps though, and larger fans can be quieter since they can get good airflow at low RPM.

Most fan systems on amps are under-engineered - low-volume usage seems not to be a primary design consideration, and variable fan speed controllers too much effort to design it seems.

Edited by dannybuoy
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48 minutes ago, fretmeister said:

Should be built where below a certain setting on the volume knob they just stay off completely.

Unfortunately from a cooling requirement PoV it doesn't always work that way. In my guitar playing days I used to run a Marshall PowerBreak with my combo and some of the more extreme effected sounds would send the fan on that into overdrive irrespective of output volume setting of the amp or the amount of speaker attenuation being applied by the PowerBreak. And that fan cooling was definitely being needed with those sounds.

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1 hour ago, BigRedX said:

Unfortunately from a cooling requirement PoV it doesn't always work that way. In my guitar playing days I used to run a Marshall PowerBreak with my combo and some of the more extreme effected sounds would send the fan on that into overdrive irrespective of output volume setting of the amp or the amount of speaker attenuation being applied by the PowerBreak. And that fan cooling was definitely being needed with those sounds.

A tube amp with a power soak sounds like a different scenario though, they're designed to push the amp harder at lower volume levels for a start.

Strange how some Class D heads have no fan at all and manage just fine. Neither did my Orange AD200B which put out a lot of heat but no fan needed. Makes me wonder how many of these amps would survive just fine with the fan ripped out as long as there was a decent heatsink!

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12 hours ago, dannybuoy said:

Strange how some Class D heads have no fan at all and manage just fine. Neither did my Orange AD200B which put out a lot of heat but no fan needed. Makes me wonder how many of these amps would survive just fine with the fan ripped out as long as there was a decent heatsink!

Very bad idea, amps are designed as a complete system, each part exists because of other parts and their needs.

I think we will see more fans on tube amps (as an example) as the new EU driven safety standard comes into effect at the end of the year. Many of the safety related changes relate to both internal operating temperatures (specifically of transformers) and external touch temperatures. This is something that was driven by the EU starting about 15 years ago but took until now for everybody to "agree", or at least not kill each other over it. 

As power densities increase (watts per cubic inch or cm), so does the need for mechanically assisted cooling, there's no getting around this until switching devices become more efficient (for class D and SMPS). It's getting better, but still not there. 

 

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On 11/09/2020 at 17:11, dannybuoy said:

Makes me wonder how many of these amps would survive just fine with the fan ripped out as long as there was a decent heatsink!

An effective heatsink might be large, which would put people off buying them. The packing density of components on class D modules is high, in order to keep them compact, so it would be difficult to add a good sized sink to them.

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It's not just the size of the heatsink, but the effectiveness of transferring heat to the ambient environment. A good deal of thermal engineering goes into high quality designs, it's not the kind of solution you pull out of your butt (or bum) because that's how you end up with thermal problems and noisy fan designs.

Edited by agedhorse
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On 01/09/2020 at 21:43, cord.scott said:

I have two main amps

Mesa d800+

Aguilar AG 700

The mesa is dead quiet and the Aguilar sounds like a jet taking off. Well maybe not that loud, but you get the point.

Has anyone every swapped these fans out for something quieter? 

I had two TH350s, a TH500 and tried out the AG700 and TH700.

All the Aguilar amplifiers use the same fan - whether they are loud to you or not is subjective but they're too loud for me.

It's down to the quality of the parts used I think.

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