Salas hotrodded blue DCB1 build - Page 108 - diyAudio
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Old 26th May 2011, 02:21 AM   #1071
Marra is offline Marra  United Kingdom
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Don't think it matters its just that its how I wired mine and its so quiet I sometimes think I've forgotten to turn it on....and then the music starts
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Old 26th May 2011, 03:06 AM   #1072
Marra is offline Marra  United Kingdom
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Lucas I see you're using an LDR volume control with your DCB1; its a great combination don't you think? I've just fitted one in my unit and it blew the switched attenuator that I'd been using out of the water; well pleased.
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Old 26th May 2011, 08:26 AM   #1073
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Quote:
Originally Posted by Marra View Post
Lucas I see you're using an LDR volume control with your DCB1; its a great combination don't you think? I've just fitted one in my unit and it blew the switched attenuator that I'd been using out of the water; well pleased.
Yea, I hated the clicky clack of the stepped attenuator I had in before, and wanted a nice smooth volume pot, but didn't want to put my signal through carbon after going to such lengths to keep it short, simple, clean. The LDR solution is the answer, and of course allows a remote control to be fitted that is completely isolated from the circuit. So, yeah, it is an ideal combination I think. Sound wise, I can't say it's any improvement, but then I wouldn't expect an improvement over a pair of quality resistors - that's also pretty clean.
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Old 26th May 2011, 08:29 AM   #1074
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Originally Posted by Marra View Post
Don't think it matters its just that its how I wired mine and its so quiet I sometimes think I've forgotten to turn it on....and then the music starts
I have a thought - the main comes in to the power amp, and is then linked through to the pre-amp. Perhaps separate IEC cables to the sockets will sort it - I'll go check now!
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Old 26th May 2011, 09:44 AM   #1075
AndrewT is offline AndrewT  Scotland
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Hi,
The primaries of the transformer are "LIVE".
Do not connect any of them to Earth, nor Ground, nor anything else.

The extra secondary could be an "Earth" from the transformer core. The transformer core is exposed and you don't want that becoming "Live" in event of a primary winding failure.
Connect the secondary Earth to Chassis.
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Old 26th May 2011, 10:41 AM   #1076
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Quote:
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Hi,
The primaries of the transformer are "LIVE".
Do not connect any of them to Earth, nor Ground, nor anything else.

The extra secondary could be an "Earth" from the transformer core. The transformer core is exposed and you don't want that becoming "Live" in event of a primary winding failure.
Connect the secondary Earth to Chassis.
OK, I get that Andrew. So, this buzz that comes from the transformer and into my speakers, gets into the signal GND because they are both linked to the star GND at the IEC EARTH terminal. Where do I use a CL60 to provide a degree of isolation for the signal GND? Do I connect the signal star GND to the mains GND via a CL60, or what?

Many thanks
Lucas


By the way, did you get your remote volume working yet? I found the supplied pot terminals to be ridiculous, so I swapped it out and Frankensteined the motor onto another alps pot. None of the terminals needs to go to the remote board - only the two motor terminals.
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Old 26th May 2011, 11:47 AM   #1077
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Sorted it with 3x CL60s

The first between the two centre tap wire of the transformer (as I saw in a Nelson Pass power supply schematic)

The second between the pre-amp signal and IEC Earth connection. Still buzzing at 50Hz!!!

OK, opened the power amp and CL60ed the signal to Earth in there too. Sorted! Silent as the dead of night! It was transformer buzz going through the inter-connects.
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Old 26th May 2011, 11:50 AM   #1078
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The drop across RcurrentSet has to do with the Vf of the 3 leds minus the Vgs of the CCS Mosfet. The most productive is you arrange the I=V/R via proper R value to target I than changing leds or Mosfet. Vgs will also differentiate for different currents a little.

I would nick just after the rectification, tapping off the filter cap to a 3 legged chip for the sub circuit needed. Don't overload the 7812 (you saw the result).

That with the illuminated leds was by using one secondary across the Tx connector I suppose, not middle and next inserts.
Thank-you Salas.

I will add another basic regulator circuit with a 78 series regulator.

The buffer worked with only one half of the transformer 2ndary connected - all leds nice and bright!. I suppose that 21v AC when 1/2 rectified with those large PS caps was enough to five decent +/- DC output. it even sounded good!

just ruined my 12mm thick alu front panel with a wrong router setting, so will have to wait b4 I can complete the pre-amp and put it in my system.

Brad
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Old 26th May 2011, 12:07 PM   #1079
Salas is offline Salas  Greece
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The CCT can work on +/- 5V floating, but you cut max swing to half.
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Old 26th May 2011, 03:25 PM   #1080
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Quote:
Originally Posted by LucasAdamson View Post
Sorted it with 3x CL60s

The first between the two centre tap wire of the transformer (as I saw in a Nelson Pass power supply schematic)

The second between the pre-amp signal and IEC Earth connection. Still buzzing at 50Hz!!!

OK, opened the power amp and CL60ed the signal to Earth in there too. Sorted! Silent as the dead of night! It was transformer buzz going through the inter-connects.
Hi Lucas
Nice tip you've mentionned and shared.
I've got to remember it as a sticky rule
Cheers
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