Spectral dma 260 hum
- Thread starter gratefulgroveway
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garylkoh
WBF Technical Expert (Speakers & Audio Equipment)
As someone who lived in 230V land, and now living and designing in 115V land (for both 115V and 230V) - there are two big issues - DC offset and 50Hz vs 60Hz.
When transformers are designed in USA (60Hz), sometimes we just take a step-up transformer or a variac and test it at 230V. In my experience - big mistake. A transformer that is totally quiet will hum and buzz and rattle when tested actually at 50Hz. I've found two solutions, but both expensive. The Burmester power conditioners all zero-out the DC offset. Secondly, the IsoTek Synchro powercord which attempts to promote a perfectly symmetrical sine wave. Both try to do the same thing in different ways.
When transformers are designed in USA (60Hz), sometimes we just take a step-up transformer or a variac and test it at 230V. In my experience - big mistake. A transformer that is totally quiet will hum and buzz and rattle when tested actually at 50Hz. I've found two solutions, but both expensive. The Burmester power conditioners all zero-out the DC offset. Secondly, the IsoTek Synchro powercord which attempts to promote a perfectly symmetrical sine wave. Both try to do the same thing in different ways.
Yeah I really do hope the manufacturers did not make the mistake of using incorrect transformers relating to 50-60hz, but mistakes can happen depending on the build process used.
Relating to the DC issue, the hambuster seems the cheapest option I have seen over here in the UK - if it fully resolves it.
One other thing, if the voltage is slightly too high this can also cause buzz if I remember due to saturation.
But if suffering a buzz, 1st thing I would suggest is take the component round to a friends and see if it still happens.
Thanks
Orb
I did try a humbuster III in several configurations, Humbuster in front of power conditioner (Running Springs Audio) and all components, humbuster in front of Spectral components (with and without power conditioning), Humbuster in front of just preamp (with and without power conditioning), . I noticed no reduction in hum from the preamp.
Oh dear, well I guess sometimes cheap is not always best sorry to hear.
Dan, you able to take the component to a friend's house?
Just needs to be the one that buzzes.
If it still buzzes there, then a good chance I would say the transformer is incorrect.
Gary, got any suggestions?
Cheers
Orb
garylkoh
WBF Technical Expert (Speakers & Audio Equipment)
If you are in the UK, see if you can find a store that would let you borrow the Isotek Synchro to try out. It's far harder to get one to try in the US, but they are quite widely distributed across the pond. I don't think that the Humbuster or the IsoTek Neoplug will work with buzzy transformers.
I don't know enough about how Spectral designs the front end of its power supplies forward of the primary windings of their power transformer. If it was one of my speakers/amplifiers I would have suggested that you reverse the polarity of Live and Neutral. Depending on the design of the Spectral, it could just sound bad, or something might break.
Finally, something that people have called me crazy for - put the amplifier upside down.
I don't know enough about how Spectral designs the front end of its power supplies forward of the primary windings of their power transformer. If it was one of my speakers/amplifiers I would have suggested that you reverse the polarity of Live and Neutral. Depending on the design of the Spectral, it could just sound bad, or something might break.
Finally, something that people have called me crazy for - put the amplifier upside down.
Spent some time at my dealer. The hum is about half that I hear at home. The preamp has some hum, but as expected according to the dealer. I will investigate my line voltage and polarity. I can also look for a source of noise by taking the pre to each room and listen for increased transformer noise.
Okay I'll bite. How do you impregnate a transformer. And would not that just produce a lot of little nosier transformers.
You need a signed consent form before you start the process.
I am very very concerned that the thread I began about a hum has been co-opted by comedians!
Gentlemen, and ladies, hi-fi is far too serious to crack jokes about!
Gentlemen, and ladies, hi-fi is far too serious to crack jokes about!
garylkoh
WBF Technical Expert (Speakers & Audio Equipment)
Okay I'll bite. How do you impregnate a transformer. And would not that just produce a lot of little nosier transformers.
It is a term used by transformer manufacturers. You impregnate the coils with a resin to reduce any chance of the coils vibrating, and you can also impregnate the plates. Basically, the transformers are put into a big tank. All the air is sucked out of the tank with a vacuum pump, and the resin injected. Sometimes, the tank and the transformers are heated so that the resin will flow better into the space between the coils.
The cheap transformers are just dipped into a tank of resin. That coats the outside but doesn't properly impregnate the coils.
No it's not. If we can't have a laugh at this wacky hobby of ours from time to time we really have some problems!
True but this problem is annoying to say the least when one has spent a fair amount of cash on the product only to find one of the transformers is giving grief (either due to build-spec or more usually it seems to mains issue as is happening for us in this thread).
I can smile but after 9k on a transport this is not a problem I wanted, ironically I went with this product as mechanically is superbly silent, so silent the freaking transformer is doing my head in at low volume hehehe
And the issue for me is the house mains/electrics and maybe this is something the manufacturer cannot design fully for, but those like me with this problem are not happy its happening, especially when other good kit is fine.
Just a heads up to those with the problem, I may be trying the Isotek Synchro in next week or so as I just purchased new standmounts from a dealer who sells them (will see if he can loan me a Synchro with delivery of the speakers).
Cheers
Orb
It would help to try and pool experiences and solutions at this point. My dealer is in the process - he says - of discussing my problem (a humming DMA260) with Spectral. I have not gone on the phone to the company myself because I think it is the reasonable responsibility for the dealer to find a solution. Certainly for such an expensive piece of kit - and my heavy duty investment in Spectral - where I am is not satisfactory.
When I hear his practical solution to the problem - be it send the amp back or some other - I will report here. It would be good to hear what other members are doing and achieving.
I am aware of how delicate or set up dependent Spectral can be and I wonder if there is something in how my cables are running that is generating hum?
Thanks
When I hear his practical solution to the problem - be it send the amp back or some other - I will report here. It would be good to hear what other members are doing and achieving.
I am aware of how delicate or set up dependent Spectral can be and I wonder if there is something in how my cables are running that is generating hum?
Thanks
Myles
I have tried different cables. Indeed I have experimented with the amp unconnected. It still hums. As pointed out this is the 2nd 260 I have had in the house. Both hum.
Paul
I have tried different cables. Indeed I have experimented with the amp unconnected. It still hums. As pointed out this is the 2nd 260 I have had in the house. Both hum.
Paul
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