No ADSL connection all day yesterday! Frustrating if you're trying to sort something out but strangely liberating too! Back up now.
Offie, I pointed to those sinks for those MOSFET's in this application - they're cheap as chips, available worldwide and keep the devices at a regular temp that's not too hot. I thought I'd offer something back to the forum instead of just asking stupid questions.
Andrew - my understanding is that the twisted pair should be of the Flow and Return wires for each channel. I'm assuming that the middle pin of the molex and what's called the GND tag of the pot are where the Return side of the pair connect. What I was trying to ask is if I'll have to take two wires off those to twist with each of the Flow wires - so the twist is the Flow and Return. I don't understand why (for example referring to the RCA to pot connection) joining those Return routes at the pot is any different from joining them at the socket tags.
It looks like for each 'stage' (RCA in to pot/pot to DCB1 in/DCB1 out to RCA out) I have to make two twisted pairs from three connectors - is that right? Thanks for your time by the way, I'm being a bit slow but I'll get there!
Offie, I pointed to those sinks for those MOSFET's in this application - they're cheap as chips, available worldwide and keep the devices at a regular temp that's not too hot. I thought I'd offer something back to the forum instead of just asking stupid questions.
Andrew - my understanding is that the twisted pair should be of the Flow and Return wires for each channel. I'm assuming that the middle pin of the molex and what's called the GND tag of the pot are where the Return side of the pair connect. What I was trying to ask is if I'll have to take two wires off those to twist with each of the Flow wires - so the twist is the Flow and Return. I don't understand why (for example referring to the RCA to pot connection) joining those Return routes at the pot is any different from joining them at the socket tags.
It looks like for each 'stage' (RCA in to pot/pot to DCB1 in/DCB1 out to RCA out) I have to make two twisted pairs from three connectors - is that right? Thanks for your time by the way, I'm being a bit slow but I'll get there!
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Ok, I'll try that, thank you. I'll have to bin the molex plug - it was trying to fit two wires into the centre pin arrangement that put me off twisted pairs.
At the pot I have a signal ground on each channel so that works. How about the RCA to pot connection? Shall I separate the RCA socket tags that I soldered together and run each signal ground separately (but twisted with its corresponding Flow wire) to its channel on the pot? I think I'm getting somewhere
At the pot I have a signal ground on each channel so that works. How about the RCA to pot connection? Shall I separate the RCA socket tags that I soldered together and run each signal ground separately (but twisted with its corresponding Flow wire) to its channel on the pot? I think I'm getting somewhere
I did fit both signal grounds (0.5mm diam copper) into the molex tag inside that middle hole.
It did not look nice and slightly misaligned the tag/blade.
I took the connector off and soldered it eventually.
A 4way pin and connector would have been far better and not wasted any space, even for a 6 input 1 output Mez.
I'll have to do that Andrew, the molex plug is looking a bit 'tired' after me trying to cram thicker wires than that into it.
Looking back there seems to be an element of 'mixing' of channels around the pot with one prevailing, maybe because I've not been methodical with the signal grounds. Does the RCA to pot proposal above look ok (i.e. keep them separate)? If I do that then I probably won't need to link the pot tags to eliminate the savage hum I was getting - the link will be at the molex centre tag.
Looking back there seems to be an element of 'mixing' of channels around the pot with one prevailing, maybe because I've not been methodical with the signal grounds. Does the RCA to pot proposal above look ok (i.e. keep them separate)? If I do that then I probably won't need to link the pot tags to eliminate the savage hum I was getting - the link will be at the molex centre tag.
The two channels are separate. Keep them separate, but close together. The twisting reduces crosstalk.
It's this twisted Flow and Return pair that should never be contravened.
Keep the input RCAs close together.
The reason for this channel to channel close proximity is to reduce the area of the ground loop of two channel and multichannel amplifiers that are fed from a pre/source that has a commoned Signal Ground.
I posted a link to a paper that discusses and solves/attenuates the interference in this multichannel ground loop.
It's this twisted Flow and Return pair that should never be contravened.
Keep the input RCAs close together.
The reason for this channel to channel close proximity is to reduce the area of the ground loop of two channel and multichannel amplifiers that are fed from a pre/source that has a commoned Signal Ground.
I posted a link to a paper that discusses and solves/attenuates the interference in this multichannel ground loop.
I wanted to say thanks for your time and patience but I've clogged up enough of this thread so I thought I'd take it offline.
I think you linked to this http://www.diyaudio.com/forums/diya...udio-component-grounding-interconnection.html so I'll have a good read. I'll report back on how I get on!
I think you linked to this http://www.diyaudio.com/forums/diya...udio-component-grounding-interconnection.html so I'll have a good read. I'll report back on how I get on!
Found it
Grounding by Daniel Joffe
http://www.diyaudio.com/forums/soli...ichael-bittner-our-mikeb-198.html#post4024136
Note WHERE the added resistance is actually located. The added resistance must not add to the signal voltage to be read by and amplified by the next amplifying stage.
Grounding by Daniel Joffe
http://www.diyaudio.com/forums/soli...ichael-bittner-our-mikeb-198.html#post4024136
Note WHERE the added resistance is actually located. The added resistance must not add to the signal voltage to be read by and amplified by the next amplifying stage.
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I'm stumped! I've run twisted pairs from the RCA's in to the pot, twisted pairs from the pot to DCB1 in (soldered direct to the bare molex pins so that I can fit two signal ground wires to it) then twisted pairs from DCB1 out to RCA out. I'm pretty sure everything is connected to the pot as it should be.
There was quite a bad ground loop (from a DAC and an ipod - same with both) but that disappears completely with a connection from the DCB1 PSU 0v to the chassis ground - I'll look into the diode/resistor permanent connection. No problem there.
But... no sound on either channel now The strange thing is that when I pull one of the RCA input plugs out I get one full (very nice sounding ) channel but when I plug that RCA back in it wipes the sound out/mutes it on both channels. Any ideas what that could be?
There was quite a bad ground loop (from a DAC and an ipod - same with both) but that disappears completely with a connection from the DCB1 PSU 0v to the chassis ground - I'll look into the diode/resistor permanent connection. No problem there.
But... no sound on either channel now
The strange thing is that when I pull one of the RCA input plugs out I get one full (very nice sounding ) channel but when I plug that RCA back in it wipes the sound out/mutes it on both channels. Any ideas what that could be?
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Hi Salas, only the left channel is working. The source is fine, either RCA out from that will play through the left channel of the DCB1. The amp is fine too, the left channel out of the DCB1 plays through either amp channel.
The odd thing is that the left channel of the DCB1 only works when only the left RCA in is connected. When I connect the right RCA in as well as the left both channels are muted.
The odd thing is that the left channel of the DCB1 only works when only the left RCA in is connected. When I connect the right RCA in as well as the left both channels are muted.
DCB1 to amp works fine, the working DCB1 channel plays through either cable to either amp input. I've tried RCA interconnects from the DAC and a 3.5mm jack to RCA's from the ipod - same symptoms.
Previously (out of circuit) I opened the 20k pot to full volume and measured 19+ kOhms on left and right tag 2 so that looks ok.
Previously (out of circuit) I opened the 20k pot to full volume and measured 19+ kOhms on left and right tag 2 so that looks ok.
OK. Now disconnect DCB1 from A1. Turn up DCB1's pot to full, feed some busy and loud music to both channels. Get your DMM to ACmV or ACV selection. Stick the black probe to the any DCB1 earth point or chassis if connected to DCB1 0V. Red probe to each leg of all 220R resistors. Note down where is a reading or not, and the channel. Let us know.
