KPA1500 fan noise concern

[Ralph Parker-2]

I'm on the list for a '1500, expected sometime in August (maybe).
However, I'm getting concerned about the reported high fan noise level.
I currently have a '500, and following a suggestion a year or two ago,
I've turned the fans around 'backwards' and they seem to be quieter in
this configuration. I would give the '500 a "quiet" in the noise
department. Temperature does not seem to be an issue.

In addition, I have an Acom 1000, which is also a quiet amp - fan as
well as relays. Hard to hear it in operation (but the 3 minute warmup
usually seems like three hours. :-)

I ordered the '1500 In the quest to be a couple of instant db louder,
but if I don't hear some resolution of the noise 'problem', I'm going to
put the order on hold until it is solved. I do have many headsets which
I usually wear, including the Bose QC15 noise cancelling model, but I'd
hate to be FORCED into using them.

A concerned citizen.

VE7XF
(over 30 years of sound recording wearing a headset)

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[K9MA]

My KPA1500 seems to max out at about 65 C when running and calling CQ. 
At that temperature, the fans are just barely audible with the
Radiosport headset.  That would be way too loud for me with any other
headset I've used, let along a speaker.  While it has other big
advantages, the noise level is about as bad as that of my old AL-82.  Of
course, the KPA1500 could be located in another room.

73,
Scott K9MA


On 5/28/2018 13:24, Ralph Parker wrote:

> I'm on the list for a '1500, expected sometime in August (maybe).
> However, I'm getting concerned about the reported high fan noise level.
> I currently have a '500, and following a suggestion a year or two ago,
> I've turned the fans around 'backwards' and they seem to be quieter in
> this configuration. I would give the '500 a "quiet" in the noise
> department. Temperature does not seem to be an issue.
>
> In addition, I have an Acom 1000, which is also a quiet amp - fan as
> well as relays. Hard to hear it in operation (but the 3 minute warmup
> usually seems like three hours. :-)
>
> I ordered the '1500 In the quest to be a couple of instant db louder,
> but if I don't hear some resolution of the noise 'problem', I'm going
> to put the order on hold until it is solved. I do have many headsets
> which I usually wear, including the Bose QC15 noise cancelling model,
> but I'd hate to be FORCED into using them.
>
> A concerned citizen.
>
> VE7XF
> (over 30 years of sound recording wearing a headset)
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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--
Scott  K9MA

[hidden email]

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[Carl Yaffey]

Well, I manually set the fan to 2 when I’m going to use the amp heavily. It’s a bit noisy but acceptable to me.
73


Carl Yaffey  K8NU
Recording studio.
[hidden email]
614 268 6353, Columbus OH
http://www.carl-yaffey.com
http://www.grassahol.com
http://www.bluesswing.com

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[Jim Brown-10]

On 5/28/2018 11:24 AM, Ralph Parker wrote:
> I ordered the '1500 In the quest to be a couple of instant db louder,
> but if I don't hear some resolution of the noise 'problem', I'm going
> to put the order on hold until it is solved. I do have many headsets
> which I usually wear, including the Bose QC15 noise cancelling model,
> but I'd hate to be FORCED into using them.

This is exactly one of the many issues that Acoustic Consultants address
in the design of buildings that house recording studios, concert halls,
and student practice halls in music colleges. I regularly worked with
world-class guys in my own consulting practice, which only did sound
system design, and I learned just enough to know that I shouldn't try to
do their work. :)  There are many elements to the design problem, and
the fan itself is only one of them. Other elements I'm aware of is
turbulence of air flow, mechanical vibration coupled from the fan to the
structure to which it is mounted, where the fan(s) are located, and so on.

I don't know if one of them was involved with Elecraft, but if not, I'd
suggest that Elecraft buy some time from one of them. And I'd be happy
to provide names of some good people/firms. In the early K3 days, I
referred a good acoustics guy to Wayne to solve the problem of acoustic
coupling between the speaker and the synthesizer that added a sideband
to RTTY, and suggested adding the stiffener to that board solved the
problem and became a running mod.

73, Jim K9YC



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[Clay Autery-2]

I don't have a fancy schmancy degree in acoustic design, but in my 20+
years of thermal control design for computing and other electronic
products, I necessarily dealt with acoustic design as it pertains to
device chassis.  They are often competing demands.
One of my main selling points to many of my clients was that while
meeting their requirements for thermal control, I could generally
improve (reduce) the acoustic stress on their staff.  I had several
long-term relationships where they kept adding adjunct projects to the
original contract that were primarily acoustic and only secondarily
thermal control as a result.

I'd be happy to trade some "free thermal/acoustic" analysis time on the
KPA-1500 in return for the simple pleasure of having one on the bench
during the process.  <big grin>
Assuming I can produce a viable/economically feasible solution for both
the company and customer base, perhaps a deal could be reached on a
price to avoid returning the "test bed". <bigger grin>

Wayne?  Eric?

73,

______________________
Clay Autery, KY5G
[phone]

On 05/28/18 15:33, Jim Brown wrote:

> On 5/28/2018 11:24 AM, Ralph Parker wrote:
>> I ordered the '1500 In the quest to be a couple of instant db louder,
>> but if I don't hear some resolution of the noise 'problem', I'm going
>> to put the order on hold until it is solved. I do have many headsets
>> which I usually wear, including the Bose QC15 noise cancelling model,
>> but I'd hate to be FORCED into using them.
>
> This is exactly one of the many issues that Acoustic Consultants
> address in the design of buildings that house recording studios,
> concert halls, and student practice halls in music colleges. I
> regularly worked with world-class guys in my own consulting practice,
> which only did sound system design, and I learned just enough to know
> that I shouldn't try to do their work. :)  There are many elements to
> the design problem, and the fan itself is only one of them. Other
> elements I'm aware of is turbulence of air flow, mechanical vibration
> coupled from the fan to the structure to which it is mounted, where
> the fan(s) are located, and so on.
>
> I don't know if one of them was involved with Elecraft, but if not,
> I'd suggest that Elecraft buy some time from one of them. And I'd be
> happy to provide names of some good people/firms. In the early K3
> days, I referred a good acoustics guy to Wayne to solve the problem of
> acoustic coupling between the speaker and the synthesizer that added a
> sideband to RTTY, and suggested adding the stiffener to that board
> solved the problem and became a running mod.
>
> 73, Jim K9YC

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[wayne burdick]

Thanks for the offer, Clay. But we actually did extensive thermal analysis of both the heat sink and fans, tested many different fan types and configurations, and did comparative noise testing of the KPA1500 vs. a number of other amps.

As you allude to, there’s no magic bullet. Heat must be removed, with various physical and electrical constraints to be satisfied.

We have some pretty amazing thermal imaging devices that we use to examine heat signatures of electrical components. These were used during R&D, which is how we determined that two LDMOS devices were far better than one for heat distribution. We also used it to evaluate the design of our very large/very thick copper heat spreader. On the production line, we review all modules for hot spots during burn-in and make sure the cooling is working perfectly (onset temperature, air distribution around modules, etc.).

Of course supplemental cooling of various types has been used with amplifiers in the past. I believe we have a couple of customers and staff experimenting with this idea, and anything that emerges will be posted here.

73,
Wayne
N6KR

> On May 28, 2018, at 4:34 PM, Clay Autery <[hidden email]> wrote:
>
> I don't have a fancy schmancy degree in acoustic design, but in my 20+ years of thermal control design for computing and other electronic products, I necessarily dealt with acoustic design as it pertains to device chassis.  They are often competing demands.
> One of my main selling points to many of my clients was that while meeting their requirements for thermal control, I could generally improve (reduce) the acoustic stress on their staff.  I had several long-term relationships where they kept adding adjunct projects to the original contract that were primarily acoustic and only secondarily thermal control as a result.
>
> I'd be happy to trade some "free thermal/acoustic" analysis time on the KPA-1500 in return for the simple pleasure of having one on the bench during the process.  <big grin>
> Assuming I can produce a viable/economically feasible solution for both the company and customer base, perhaps a deal could be reached on a price to avoid returning the "test bed". <bigger grin>
>
> Wayne?  Eric?
>
> 73,
>
> ______________________
> Clay Autery, KY5G
> [phone]
>
> On 05/28/18 15:33, Jim Brown wrote:
>> On 5/28/2018 11:24 AM, Ralph Parker wrote:
>>> I ordered the '1500 In the quest to be a couple of instant db louder, but if I don't hear some resolution of the noise 'problem', I'm going to put the order on hold until it is solved. I do have many headsets which I usually wear, including the Bose QC15 noise cancelling model, but I'd hate to be FORCED into using them.
>>
>> This is exactly one of the many issues that Acoustic Consultants address in the design of buildings that house recording studios, concert halls, and student practice halls in music colleges. I regularly worked with world-class guys in my own consulting practice, which only did sound system design, and I learned just enough to know that I shouldn't try to do their work. :)  There are many elements to the design problem, and the fan itself is only one of them. Other elements I'm aware of is turbulence of air flow, mechanical vibration coupled from the fan to the structure to which it is mounted, where the fan(s) are located, and so on.
>>
>> I don't know if one of them was involved with Elecraft, but if not, I'd suggest that Elecraft buy some time from one of them. And I'd be happy to provide names of some good people/firms. In the early K3 days, I referred a good acoustics guy to Wayne to solve the problem of acoustic coupling between the speaker and the synthesizer that added a sideband to RTTY, and suggested adding the stiffener to that board solved the problem and became a running mod.
>>
>> 73, Jim K9YC
>
> ______________________________________________________________
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>
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> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

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