Probably a silly question - Does an aluminum speaker cabinet attract more noise?

Folsom

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Clamp on ferrites are not going to help with a sump pump level of noise. In fact most devices won't. I could send you a demo unit to see if it would help, that will work on lower frequencies a sump pump may generate.
 

cjf

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Nov 19, 2012
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Which Freq range do you believe the sump pump may puke noise out at? 60hz or something still in the kHz range?

Based on what I measured with the i-phone APP it seems most of the grunge is pretty high in the Freq band (8-16kHz) during boot up of the amps.

I think the brain box may be contributing more to some of the noise then the sump itself so I may just skip attempting to cure any sump noise because in theory it shouldn't be spinning its motor unless activated.
 

Folsom

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Yes, in audible range sounds like it might be the problem area from the sump pump & brain. The unit I was thinking about sending begins very good filtration down at 1.6k. It may also be able to dampen resonation problems the SP&B may cause.

I still recommend checking your voltage.

Which Freq range do you believe the sump pump may puke noise out at? 60hz or something still in the kHz range?

Based on what I measured with the i-phone APP it seems most of the grunge is pretty high in the Freq band (8-16kHz) during boot up of the amps.

I think the brain box may be contributing more to some of the noise then the sump itself so I may just skip attempting to cure any sump noise because in theory it shouldn't be spinning its motor unless activated.
 

cjf

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Nov 19, 2012
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Hello,

I wanted to update this thread with my latest findings in hopes that this information will save others the headache I've been battling with for the last two months. Since my last post I have been on a continuous search to find out the source and reason for the noise I was hearing in my system. Thru allot of trial and error I have come to find out that the issue was caused by my use of "short" speaker cables in my setup.

For the last 5 years or so I've been using what many may consider very short runs of speaker wire with great success from all of the mono block amps and speakers I've had in circulation in my system during that time. Well in the current system configuration I use today it turns out that the use of these short cables were the source of all my headaches reported in this thread. I am now at a point where I can reproduce the issue at will by inserting ANY cable of ANY flavor under 11ft. Then, just as quickly, I can resolve the issue by inserting ANY cable of ANY flavor longer than 11ft between my amps and the speakers. The results, quiet as a field mouse with ear resting on tweeter. Even the strange bootup noise is gone with ear resting on tweeter with a longer cable.

At least in my case, I'm fairly certain that this issue is specific to the use of a Class D amp with the Magico speakers I own. I can't say if this issue would occur with other Magico speakers or not since I only have the S3 to play with but the fact that this happens with two different Class D amps from the same manufacturer leads me to believe that its a Class D specific problem in combination with some component or component layout choice within the cross over network of the Magico S3 speakers. I make this statement with a fairly high level of confidence because if I keep everything in the system the same and change just the speaker the noise does not occur. The same can be said if I only change the amps to a none Class D style using the same speaker, the noise does not occur. While in either of these changed states, I can also use a short speaker wire without issue.

Neither the speaker or the Amps are broken or malfunctioning in any way, they just don't seem to get along when connected together with less than 11ft of speaker wire between them. This increased length somehow seems to be the magic pill that offers just enough filtration of the typical noises found within a Class D amp using an SMPS power supply to not find its way into this very resolving speakers seemingly sensitive/picky crossover network.

At this point both manufacturers have been made aware of this strange finding but I'm not confident anything will ever come of it. So other than the additional expense of having to buy longer cables I'm pretty happy that the fix turned out to be something simple and cheap (in the grand scheme of things). I still wouldn't hesitate to recommend this pairing of equipment to others because it really is damn good as long as they can live with the expense of using a longer speaker cable for no other reason but to avoid the possibility of hearing interference/noise out of the speakers.

Well that just about does it for me. Now I just need to finalize my choice of which speaker wire I am going to purchase at a 4meter length so I can get back to enjoying the music :)
 

Folsom

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RLC, three properties that increase some with length.

Something must have been resonating. Crossover & binding posts, speaker wire, and the output indicator may not have been doing well. Maybe it has to do with elliptical crossovers.

ClassD have output filters, they don't need Zobels like other amps as far as I know; so it's probably not the class topology so much as the output filter.
 

Barry2013

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I'm coming late to this thread CJ, but I have KG Kipod Signature passives which as you'll know have aluminium cabinets.and I have never had the problems you describe.
My system is extensively Entreqed and includes amp negative speaker out puts grounded to a Poseidon ground box and it has been one of the best Entreq applications I have used. I really do not know if it would cure your problem but thought I would share that with you in case you wanted to consider it.
 

cjf

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Nov 19, 2012
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So are you guessing the change in resistance of the different length cables is the cause?

Hello,

I'm not sure if its a change in resistance or not because when trying many different types of wire during my testing each of them had different resistance values based on the length and wire gauge used at the time of the test. Wires that would have most likely had more resistance due to a smaller gauge showed the same results (up to a point) as other wires that would have had less resistance due to them being a larger gauge. But with that said, it did seem that the thinner gauge wires I used could be of a slightly shorter length and not generate noise. By this I mean if I used a 20ga Monster XP cable at 10ft it would not result in noise but if I switched to a larger 10ga no name wire at a length of 10.5ft the noise would still be present. Using that same larger 10ga wire at a distance of 11.5ft would result in the noise going away.

Currently my primary reference speaker wire is Cardas Golden Reference which is a whopping 3.5ga!! per pole and noise is present at its 3meter length. Technically speaking, 3meters is just under 10ft so I'm not surprised the noise is still present in this configuration. I'm going to keep my fingers crossed that should I choose another Cardas cable of similar "heft" that my planned 4meter purchase will result in no noise also. But I wont know for sure until I get some in my hands to try out. At the distances used for my purposes resistance differences should be very small but when taking the monster Cardas wires into consideration resistance is probably non existent so I'm hoping resistance isn't the cause.

I'm actually leaning more towards the extra length of wire acting more like a filter which soaks up the HF noise just enough to make it inaudible before it reaches the speaker terminals but this is certainly not my area of expertise and am merely speculating from my arm chair engineering seat :)
 

cjf

Well-Known Member
Nov 19, 2012
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948
RLC, three properties that increase some with length.

Something must have been resonating. Crossover & binding posts, speaker wire, and the output indicator may not have been doing well. Maybe it has to do with elliptical crossovers.

ClassD have output filters, they don't need Zobels like other amps as far as I know; so it's probably not the class topology so much as the output filter.

I have a feeling your probably correct about the elliptical crossover filtering found inside the speaker not playing well with the output filter on the Class D amp when connected at short distances from each other. It could be the extra wire is either filtering the noise or its offering up some form of buffer which calms the resonances that are occurring between the two circuits. Who knows!
 

cjf

Well-Known Member
Nov 19, 2012
452
101
948
I'm coming late to this thread CJ, but I have KG Kipod Signature passives which as you'll know have aluminium cabinets.and I have never had the problems you describe.
My system is extensively Entreqed and includes amp negative speaker out puts grounded to a Poseidon ground box and it has been one of the best Entreq applications I have used. I really do not know if it would cure your problem but thought I would share that with you in case you wanted to consider it.

Hello Barry2013,

I have found the issue to my problem and it turns out that the metal cabinet isn't the cause. During my initial post I was just curious if such an issue could be caused by a metal speaker cabinet acting like an antenna but that doesn't seem to be the case, luckily.
 

Folsom

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Oct 25, 2015
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Longer cables might provide just enough resistance to dampen the setup. Filtration isn't a very likely scenario.
 

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