Power consumption of Pulse 2
Answered
Hello!
I recently bought a second hand Pulse that is five years old. I think it works as advertised, at least having read up on some peoples issues with the standby mode causing a high pitched hiss or buzz. I've grown quite tired of listening to it and reached out to an audio engineer friend who suggested that a class D amp shouldn't really draw any real power if not playing. I hooked the speaker up through a power consumtion meter and when silent but out of standby mode it draws 13,5W. When playing at a comfortable level, just at the border of drowning out conversation a couple of meter away from it, it draws 14,5W. In standby mode it draws just under 5W.
So my idea to just turn off standby mode maybe isn't that viable considering the "always on" design.
My audio engineer friend had a few different ideas as to what may be causing he hissing, one being that an odd transistor in the amplifier design is left on in standby mode, causing the hiss. Another idea is that the DA-converter is left on and some signal is bleeding through. However, the real mystery to me (apart from a power save mode actually producing more sound than an active mode) is why the speaker draws almost as much power when silent as when playing. This is an unfortunate combination of factors as I really would prefer this unit to be silent when not playing.
The thought of just disconnecting it had occurred to me but then having to deal with the time it takes to reconnect to the network is prohibitive. Although, its not that much worse than the current 30-45 seconds it now takes from pressing play on Spotify, even when standby mode is not active. My Powernode 2i starts playing instantly as a comparison.
What is the standby mode in the Pulse actually doing? What is it turning off? And why is it making more noise whan in standby mode than when music is not playing but it is out of standby mode?
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Official comment
Hi Karl
What you are describing is not normal nor what is expected of the PULSE. It is likely defective. You mentioned you purchased it second hand so as a result you likely are not eligible for any warranty or after warranty options. Please check out www.bluesound.com/stored and click the link to view Distributors. Depending on your country, some of our regional distributors (but not all) may offer repair options. The PULSE however, being an all in one product is sealed so any possible repairs may not be worth it compared to re-purchasing.
I am sorry to hear about your predicament but this could be an example of why it may be best to stick to an authorised re-seller.
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Thank you for replying.
My hope here was to glean some actual information about the product and how the amplifier topography is arranged. My hope was that something might be done to reduce the noise, either by filtering the power input in some way or by a software fix.Bluesound products has a good reputation in Sweden where I am located and I would expect the components in them to last longer than five years, at the price point they are at. In my opinion, a good quality product should be able to handle a couple of owners and getting good quality products second hand is usually a very good option resource wise, for both consumer and from a waste standpoint. I find that most companies that do sincerely back up their products will still be helpful when issues arise, even if they have been re-sold. I had hopes of this applying to Bluesound as well, but after reading several tales of tech support interactions I'm starting to get the impression that that will not be the case.
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Karl, in case you still own the hissing Pulse 2. I had the same experience with two pulse 2 speakers. One died and was replaced under warranty by a Pulse 2i (HiFiKlubben service), and the other one died a couple of weeks ago.
I decide to take it apart and inspect the boards, especially the capacitors. Only poor unknown quality caps are used, some even rated 85 degrees. The KSC 1000uF 35V caps on the amp board were bulged.
I recapped both amp board and power board with Panasonic and Nichicon caps of the same values. Quite straightforward if you have some experience in soldering (and have access to a desolder station).
After recap the sound is crisp as new and the hissing is completely gone. Dead silent. So the design is good, the components are bad. No pulse 2 speaker will last 5 years “always on” without a recap.
So if you or anybody else has a dead Pulse 2 (solid RED led), recapping it turns it as new. Also improving sound quality a lot, bulging caps on the amp board and out of spec PSU is not helping sound quality.
My two cents!
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Hi Diederik, thanks for the information. I have two new flex units with hissing, high pitched periodical noise when in standby. I notified support, but found a thread mentioning this issue 4 years ago (static noise). Do you think a change of same components might help? It sounds like crap in the bedroom at night (standby). I thought its some bleed from internal WiFi components into the speaker circuit inside. Best regards, Daniel
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Hi Daniel, I have to correct my earlier findings. Replacing all electrolyte capacitors made the Pulse 2 work in fine order, but my children could still hear the hissing.
I opened it again and found a ceramic disk capacitor in the high voltage circuitry as cause. I suspect this cap is there to dampen voltage spikes through a diode. I low load conditions this might be too much for this cap.
I will replace it with a new one and also try a film cap in its place.
I suspect the PSU (and other board as well) of these units is build with economics in mind rather than silence and durability. Whining ceramic disc capacitors can be replaced with better parts that will be silent.
I have three flex 2i players and two are in my daughters rooms. If they start hissing while in standby I will take them apart as well.
To answer your question: it can be repaired, but I suspect the bleusound repair service only replaces boards (with again some crappy components) and will not replace components with better parts. However, there are repair shops who will do that for you. You may even have a friend who can do this for you. Better for you and our planet.
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Hello Diedrik, thank you for your insights! I kept tracing the issues with my “red dead” Pulse 2 and managed to find a smoking and cracked open component on the amplifier board. I suspect it’s a voltage regulator. At that point I was a bit sick of the whole thing and decided to place the project on hold. I did however confirm that the PSU board did deliver the correct voltage before probably getting some sort of faulty feedback reading and entering the amp into amplifier protect mode.
The good news though is that I’m confident I’ve found the source of the hissing in standby mode. There is a rather small transformer at the top right corner of the PSU board. It is not potted. I think what I’m hearing is “coil whine” from it. Apparently a typical behavior from unpotted (or poorly potted/aged potting agent) transformers of this scale when they are idling and not under load. My plan has been to epoxy pot this transformer under a vacuum but I’ve not gotten around to it yet.
Whether or not both the issue with the whining transformer and the busted voltage regulator is due to bad capacitors is outside of my knowledge. And I suspect the regulator will be difficult to source. If you have a good source for capacitors of decent quality with a form factor the will fit the Pulse boards I’d love to hear it! Sounds like you are in Sweden as well? I bought some caps from mouser but it became overly expensive for just a few parts.
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