| Author |
 Topic  |
|
|
Laurie
Double Platinum Member
Canada
4854 Posts |
 Posted - 02/24/2008 : 00:14:45
|
G'day! I have a DS-2 that is proving troublesome. It's "old" (maybe 5-10 years - don't know for sure because I bought it from the local Cash ConvertOrs).
Anyway, the symptom is that when the pedal is turned on a probably 2kHz noise is injected into the chain, even with no signal into the pedal, and even with the input shorted to ground. This happens with the DS-2 powered by a 9VDC regulated multi-pedal supply that runs all my other pedals, and also with a PSA-120T connected only to the DS-2.
Here is the interesting thing though... the DS-2 is on a "true bypass loop" - I have a pedalboard with external footswitches that trigger relays that switch the pedals entirely in or out (the signal wire to the pedal is switched by the relay, but not the ground wire). The 2kHz noise is injected into the chain when the DS-2 is on, but true-bypassed, leading me to think the noise is being injected onto the ground wire?
Has anyone seen *anything* like this before?
Thanks, and regards,
Laurie
DS-2, NF-1, PH-3, CH-1, BF-2, SD-1, DS-1 (seeing eye)
|
|
|
Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 02/24/2008 : 02:25:55
|
Hi lauries2
Please try the DS-2 on it's own & using a KNOWN GOOD battery.
to see if it's the DS-2 or something else.
I'm guessing it's from the Multi power supply.
Is it a switching type, you didn't mention what it was or the brand.
Isolating it from the rest will determine where to look next.
Good luck & welcome to the Forum.
Regards Dr. Bob |
 |
|
|
Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 02/24/2008 : 17:05:00
|
Just plugged the DS-2 back into the board to set up the test with the battery (thanks for the tip!) and the problem has disappeared. No 2kHz noise when powered by the 9V power supply - just the usual low level white noise/hum I'd expect. Thanks Dr. Bob for fixing it "by remote" ;-)
Grrrr... I hate it when this happens.
FYI - the power supply I am powering the pedals from is the "standard" 7809 regulator circuit. Works a treat for up to about 10 pedals and costs only a few dollars to build.
Regards,
Laurie.
Download Attachment:  PSU1.gif
4.77 KB |
|
|
|
Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 02/25/2008 : 07:28:10
|
Hi lauries2
Glad to hear that we were able to help you out.
I would like to know, where you think the 2Khz whine was coming from,
maybe if one of your pedals is a digital pedal?
What other pedals were/are you using with your 7809 regulated adapter?
Did you build the regulator? does it have an adequate heatsink, for he current that you might be drawing from it.
The LM780x series of regulators tend to go into a soft shutdown mode when overheated, & you might be loosing some of the regulated 9VDC,
which might be causing one of the digital pedals to misbehave under lowered voltage.
The MZ-2 does weird stuff when the volts go low, great if you can control it... 
Regards Dr. Bob |
|
|
|
Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 02/25/2008 : 08:21:17
|
G'day Dr. Bob. I have NO idea where the whine went. It was there and now it isn't.
The 7809 circuit is rock solid. 8.97VDC every time I've measured it under any and all variations of pedal load, although that's admittedly with a DMM - I haven't put a scope on it to look for HF ripple. Heatsink is an aluminium rail weighing about 1kg so no worries there.
There are two digital pedals on the line - a Behringer DR100 and a DD100 (reverb and delay) - plus a Line6 POD. No issues with noise from them with any other pedals in the chain. The total chain is as follows:
- POD 2.0
- DS-1 (seeing eye)
- DF-7 (Digitech distortion)
- PB100 (Behringer boooster)
- CH-1
- BF-2
- PH-3
- DD100 (Behringer delay)
- DR100 (Behringer reverb)
- ED-1 (Marshall compressor)
- NF-1
The chain above (no DS-2) all running now with no sign of the whine. When I plug the DS-2 into the chain between the POD and the DS-1 (it's old home), there is still no sign of the whine.
The only thing I can think of is that maybe there was some noise on the domestic 120VAC circuit that the DS-2 (specifically) reacted to. Anyway, I've swapped the DS-2 out and am using the DF-7 for the time being. I'll set the DS-2 up in a smaller chain (with a PH-2 and GEB-7) for my bass at some point and soak it to see if it whines again.
Time will tell (or not!).
Regards,
Laurie.
|
|
|
|
Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 02/25/2008 : 12:34:37
|
Hi lauries2
You have me a little confused,
you said that you are running your POD 2.x off or with the other assorted 9VDC pedals.
My POD 2.x uses a 9VAC 2000mA adapter.
While I know that you CAN run DC into a bridge rectifier, like in the POD, but you will see a loss of at least 1.2 to 1.4VDC (2 diode junctions), from the 9.8VDV off your regulator.
Or do you have the AC side of your plug pack running into the POD?
I like your L--O--N--G BOARD, you will have to tell us a bit more about it, materials, the audio patch sockets etc.
Do you have just one LM7809 Reg. or a couple, inside your LONG BOARD.
Did you take any pics of the insides?
And 20 years of connector experiments - must make you at least close to my age (C)
Regards Dr. Bob
|
|
|
|
Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 02/25/2008 : 17:42:02
|
Hi Dr. Bob! The POD is powered by the POD power supply that came with it. I couldn't be bothered rigging something up for it. Everything else runs off the 7809. The relays for the true-bypass switching are all 12VDC running off a separate unregulated plug-pack.
The POD is plugged into an insert on the "long board" (I call it a �rail�) - I have 5 insert points, 4 un-switched, and one with a true bypass switch for the POD.
I have one 7809 in the rail (pic attached). My total current draw from the pedals is about 600mA so it only needs one.
True-bypass switching is done with standard miniature DPDT 12VDC relays. The foot switches in the rail turn the relays and indicator LEDs on and off.
The rail itself is a 4 foot length of 2 inch �architectural� aluminium channel with a 2 inch plate as the base.
1/4 inch sockets are Chinese copies of Cliff types. I can't easily get Cliff products where I live at the moment, or I would have used them. The sockets have all been checked for tension and cleaned and lubed before use. Patch cords use the Chinese manufactured 1/4 inch plugs from Neutrik. I figure the patching arrangement will be OK because the plugs/sockets aren't exercised much in a pedalboard.
Yeah, I started my technical education in 1979... I guess I'm "old" too, eh?
Regards,
Laurie.
Download Attachment: board1c.jpg
84.47 KB
Download Attachment: board2a.jpg
69.61 KB
Download Attachment: board3a.jpg
35.83 KB
|
|
|
| |
Topic |
|
DS-2 noise
PSU1.gif
board1c.jpg
board2a.jpg
board3a.jpg