Hi Guys
I have been meaning to try this dc blocker and i have just installed it into my test rig amp.
http://www.diyparadise.com/dablok.html
Well I will be blowed if there isnt an net overall improvement, in particular the amount of airiness in the music. It certianly hasnt degraged the sound.. the trans doesent buzz as much either.
Anyone else tried this trick?
Nick
I have been meaning to try this dc blocker and i have just installed it into my test rig amp.
http://www.diyparadise.com/dablok.html
Well I will be blowed if there isnt an net overall improvement, in particular the amount of airiness in the music. It certianly hasnt degraged the sound.. the trans doesent buzz as much either.
Anyone else tried this trick?
Nick
Interesting idea, several things need to be mentioned:
The entire load current is flowing through those capacitors for one half of each cycle, better make sure that the ripple current rating of that cap is considerably greater than load current. Excessive heating and early failure could otherwise be the result.
As the caps age their ESR will increase, resulting in increased internal heating, eventually you could be in for some excitement as the caps fail.
Should one of those diodes fail the associated cap will be subject to the reverse voltage the diode was clamping.
Shorts on the secondary side of the power transformer may result in substantially more voltage appearing across the cap than it is rated for. I would consider replacing the diodes with high power zeners to protect against the above failure.
I'd use at least 50V caps for this application and probably more than one diode per cap just to play it safe.
The fuse should be placed before this network so in the event that something fails there is some protection against the hazards this circuit introduces under some fault conditions.
On the surface this looks like a good idea, on closer inspection I am not quite so sure - enough so that I would not use this technique with the components suggested in the note.
The entire load current is flowing through those capacitors for one half of each cycle, better make sure that the ripple current rating of that cap is considerably greater than load current. Excessive heating and early failure could otherwise be the result.
As the caps age their ESR will increase, resulting in increased internal heating, eventually you could be in for some excitement as the caps fail.
Should one of those diodes fail the associated cap will be subject to the reverse voltage the diode was clamping.
Shorts on the secondary side of the power transformer may result in substantially more voltage appearing across the cap than it is rated for. I would consider replacing the diodes with high power zeners to protect against the above failure.
I'd use at least 50V caps for this application and probably more than one diode per cap just to play it safe.
The fuse should be placed before this network so in the event that something fails there is some protection against the hazards this circuit introduces under some fault conditions.
On the surface this looks like a good idea, on closer inspection I am not quite so sure - enough so that I would not use this technique with the components suggested in the note.
If you can afford it a dedicated line is best. (I have 4) Look for old style dimmers and ancient tv sets as possible culprits that inject dc onto the power line.
Bulb savers advertised and sold in super markets and drug stores are nothing more than half wave rectifiers - if you are using any they should be removed.
Note that all of the above presupposes that there is no significant dc coming into the house. (Pole transformer not shared with neighbors, or neighbors who do not have devices that put much dc on the line.
Frankly I suspect most large utility transformers are quite good at suppressing moderate dc appearing on their windings, so it should be a local problem only. This incidentally isn't a problem I have ever encountered anywhere I have lived in MA or NH over the last 30yrs.. (Too many places to count.)
Forget about it..
Bulb savers advertised and sold in super markets and drug stores are nothing more than half wave rectifiers - if you are using any they should be removed.
Note that all of the above presupposes that there is no significant dc coming into the house. (Pole transformer not shared with neighbors, or neighbors who do not have devices that put much dc on the line.
Frankly I suspect most large utility transformers are quite good at suppressing moderate dc appearing on their windings, so it should be a local problem only. This incidentally isn't a problem I have ever encountered anywhere I have lived in MA or NH over the last 30yrs.. (Too many places to count.)
Forget about it..
not really. the way i see it, without using a dc blocker, one has two choices:
1. remove the source of the dc (e.g anything on the power lines that half wave rectifies, etc.)
2. replace the power transformers in the affected equipment with transformers that are less susceptible to the dc that is present.
ok, i guess there is a 3rd option that we don't like: grin and bear it.
peter:
what effect did you hear that makes the dc blocker not an option for you? i'm curious ...
mlloyd1
1. remove the source of the dc (e.g anything on the power lines that half wave rectifies, etc.)
2. replace the power transformers in the affected equipment with transformers that are less susceptible to the dc that is present.
ok, i guess there is a 3rd option that we don't like: grin and bear it.
peter:
what effect did you hear that makes the dc blocker not an option for you? i'm curious ...
mlloyd1
lousymusician said:
Agree with the above safety/overload considerations, but also, since the current is the same on both sides, why not put this thing on the neutral side so it isn't sitting at line potential? Given the area of the cans, my guess is any sound difference you hear is somehow related to the field, not the designed function of the device.
I built this and it does work in that it removes DC. I find that Class D power supplies (computers) can inject DC into the mains.
First of all, be aware of the numerous potential safety issues. I insulated the exposed metal on the top of the caps and used a plastic enclosure.
The response by kevinkr raises some very important long-term safety issues. They are likely enough reason to look at other options.
Changes in sound were very subtle if any. I used it for a week and put it away, not worth the risk in my mind.
First of all, be aware of the numerous potential safety issues. I insulated the exposed metal on the top of the caps and used a plastic enclosure.
The response by kevinkr raises some very important long-term safety issues. They are likely enough reason to look at other options.
Changes in sound were very subtle if any. I used it for a week and put it away, not worth the risk in my mind.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.