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TomCray
Bronze Member
USA
75 Posts |
 Posted - 05/11/2008 : 08:40:02
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When I have my DD-20 plugged in to my 1Spot daisy chain, there is a popping noise when the blue tempo LED blinks, now when the tempo is 100ms it gets really annoying 
I'm using my old PSA right now and theres no noise, also when I used the 1Spot minus daisy chain theres no noise.
I don't mind using the PSA, just wondering whats going on.
Thanks |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 05/11/2008 : 09:51:46
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Hi TomCray
This subject has been brought up a few times recently.
The dual pedals seem to require their own & individual power supply.
I postulated that it might be a problem with the dual pedals & their virtual ground arrangement.
Or when two or more are on the same supply, that the internal clocks for the microprocessors inside the pedals might be interacting or beating against one another.
Some power supplies (not sure about your 1Spot) are switching or switch mode power supplies; These also run at a very high frequency and maybe interacting with the clocks as well.
In a lot of/most cases you will be able to hear some artifacts from the switching supply, because it is just that, & not a transformer diodes regulator & filter cap, linear supply.
I was hoping that Laurie, Stinkfoot, RonNovy, Christo or one of the other Tech Heads here, might all pitch in here & offer their respective comments.
You have actually fixed the problem without knowing it or why.
Regards Dr. Bob
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bossFan
Bronze Member
Portugal
97 Posts |
Posted - 05/11/2008 : 11:10:11
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quote:
Originally posted by Dr. Bob
...when two or more are on the same supply, that the internal clocks for the microprocessors inside the pedals might be interacting or beating against one another...
The same thing happens with mr RC-2.It can�t stand beeing connected to the daisy chain.
It needs an individual PSA or else it�s high pitch noise all around.
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 05/11/2008 : 11:26:15
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Hi bossFan
I forgot about the RC-2-20-50 series.
I would hazard a guess, that this is a problem with all the newer COSM based effects,
they all have some type of Clock/Microprocessor &/or A to D & D to A converters in them.
There may be a way to bypass the virtual grounds, & supply lines to a real ground with some small (pf) value caps.
Rainy day project
Regards Dr. Bob |
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bossFan
Bronze Member
Portugal
97 Posts |
Posted - 05/11/2008 : 14:46:02
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Hi, Dr.
You are right, but i guess it would be not a rainy day but an "All Winter" project" because the schematics of these new COSM pedals, that we would need for a serious study of the supply lines,
are probably still ""In the Lap of the Gods"",so it would be a looonnnng project..
Cheers  |
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 05/11/2008 : 17:46:49
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Hi bossFan & Guys
I'm certain that these pedals have both a Digital ground & an analog signal ground, & this is where some of this noise is coming from.
Else you would still hear the noise, even when running separate power supplies.
Do you have any other ideas?
you might also have to use Ferrite type beads on certain internal Pwr & signal lines, to further reduce the problem.
Regards Dr. Bob |
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Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 05/11/2008 : 18:06:46
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The 1spot is definitely a switched mode device - the easy way to be certain is that it says "convert international voltage (100V-240V) automatically; no transformer needed". Anything that can do that - with no transormer and no changing of jumpers/switches - is switched mode.
I'd be interested to see the schematics for these COSM pedals... I suspect Dr. Bob has hit it on the head - they almost certainly have a "digital" ground for the power supply and an "analogue" ground for the signal. Chaining a pedal with dual grounds with a normal compact pedal would connect the digital ground to the analogue ground and make exactly the type of noise you describe. The standard electronic engineering fix for this is to put a ferrite inductor in the wire joining the two grounds.
The noise from switched mode power supplies is more problematic. Those of you who have read my rants on this topic know that I firmly believe that a linear supply (like the PSA) is the only way to go. It is simply not possible to remove all the high frequency switching artifacts from a switched mode supply under all conditions and for audio equipment this can bleed into the audio circuit, again giving the type of noise you describe. There is a reason switched mode power supplies generally are not used for big power amplifiers even though that style of supply is smaller and lighter.
Add to that the risk that mains voltage *might* get through to the output of a switched mode supply in the event of a failure, and I think it's a good case to not use them for pedals. Just my $0.25 rant
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TomCray
Bronze Member
USA
75 Posts |
Posted - 05/11/2008 : 21:03:40
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Thanks guys,
Kind of peeves me because I would have rather spent less on a PSA then spend $30 on an 1Spot.
Oh, live and learn,
Thanks |
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Laurie
Double Platinum Member
Canada
4854 Posts |
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Goran
Double Platinum Member
Sweden
2203 Posts |
Posted - 05/12/2008 : 12:51:42
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I have had the same trouble with switched supplies and DD-20, really noisy.
But I also have a Cioks supply (transformer based)(http://www.cioks.com/products/products.htm), and no noise even with both DD-20 and a couple of more pedals, never. And Cioks don�t have insulated outputs, they are all parallel, like a daisy chain.
Boss PSA works good but only supplies around 200 mA, and that�s what DD-20 requires�
I have also had trouble with DD-2 and switched supplies, a bit of noise.
Copied from Stinkfoots homepage;
Why no switching type adapters?
These days there are plenty of switching type supplies out there (1spot/Godlyke/Diago/Rocktron etc, and of course the Maplin/Radio Shack variants). They can deliver more current than a standard adapter of similar size, and are also said to be quieter with less hum. And still I do not recommend any adapter of that type. I'll even go so far as to strongly advise against using them. They can cause a high frequency whining noise in certain pedals (mostly clock-driven circuits like delay/reverb/chorus etc), which is not nice. Also, a problem in one of your pedals can cause them to severely damage your pedals.
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Edited by - Goran on 05/12/2008 13:03:46 |
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pedals 4 pv
Platinum Member
Canada
1351 Posts |
Posted - 05/14/2008 : 00:22:26
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I have had absolutely no problems with my Boss PSA-120S, in fact I get less noise. |
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PaulH
Gold Member
535 Posts |
Posted - 05/31/2008 : 11:25:09
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I use my DD20 with my other Boss pedals (OS2 HF2 CE5 TU12) and a Sansamp DI box all powered from the BCB60.
No noise issues at all.
I did have some noise problem, but I sourced it as my guitar pickup wiring.
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Topic |
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DD-20 and daisy chain noise?
