Especcially complete with a stepped attenuator out of a Burmester preamp. It's 10K
Ok for me to drive the "source".
I'm happy that I didn't go for a 25K.
This concept is top! This week I'm gonna do some thing with a phono pre...le pacific style. Enough 2SK170 available...in my room
I am about to begin the wiring phase of my DCB1 build after a six month layoff subsequent to completing the CB build. Could someone please describe the proper way to wire the RCA input/output jacks with respect to type of wire, twisted or not, grounding method and location? A photo would be helpful if possible.
Mark
Mark
Isolate the RCA from the Chassis.
Place the Left and Right RCA sockets very close together.
Use twisted pair to connect RCA to PCB.
At each end of the twisted pair ensure by careful placement of the wires that you have a very small loop area for least pick up of interference.
If you decide to "Ground" the input at the PCB then run the ground wire/trace to the Main Audio Ground (MAG) over the route that the other Flow Current follows through the PCB.
If you "Ground" the input at the RCA, then run the ground wire along the twisted pair to the PCB and then follow the Flow route of the other PCB currents to the MAG.
This RCA located "Ground" wire can be two wires, one from each RCA or you can couple the two RCAs and run one Ground wire back to MAG.
The input wiring is not "simple", it needs to be thought out and run carefully to maximise it's ability to reject interference. Adopting a coax does not make it any easier. In some respects a coax is more difficult.
When you come to wiring the three PSU wires, it requires just as much thought for correct routing.
Similarly when you wire up the Speaker Terminals.
All these connections to the "amplifier" are potential INPUTS and OUTPUTS and ALL need careful routing.
Place the Left and Right RCA sockets very close together.
Use twisted pair to connect RCA to PCB.
At each end of the twisted pair ensure by careful placement of the wires that you have a very small loop area for least pick up of interference.
If you decide to "Ground" the input at the PCB then run the ground wire/trace to the Main Audio Ground (MAG) over the route that the other Flow Current follows through the PCB.
If you "Ground" the input at the RCA, then run the ground wire along the twisted pair to the PCB and then follow the Flow route of the other PCB currents to the MAG.
This RCA located "Ground" wire can be two wires, one from each RCA or you can couple the two RCAs and run one Ground wire back to MAG.
The input wiring is not "simple", it needs to be thought out and run carefully to maximise it's ability to reject interference. Adopting a coax does not make it any easier. In some respects a coax is more difficult.
When you come to wiring the three PSU wires, it requires just as much thought for correct routing.
Similarly when you wire up the Speaker Terminals.
All these connections to the "amplifier" are potential INPUTS and OUTPUTS and ALL need careful routing.
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Please share with link if you do see some detailed diagram or clear picture of internal RCA wiring based on AndrewT's advises on internet. It will help to beginners a lot. I can't see any valuable and essay to read info there.
Finished building my hot rod, balanced DCB1 based on Tea-Bag's kit. Both DCB1's mounted to the same Modu 4 U 400 mm heatsink, temperature seems to be approx. 37 deg C. Using 3R3 CCS resistors, I'm measuring ~2 V across CCS resistors.
The DCB1 certainly seems to bring it's own flavor to the sound. More relaxed and "analog" presentation, maybe due to some added 2nd order distortion.
My setup is a LynxTwo-B sound card, First Watt F1J diy clone power amp and HiFiMan HE-6 headphones. Without the DCB1, sound seems a bit more transparent and tight, but lacking some of the "body" and naturalness the DCB1 brings to the table. No free lunch
The DCB1 certainly seems to bring it's own flavor to the sound. More relaxed and "analog" presentation, maybe due to some added 2nd order distortion.
My setup is a LynxTwo-B sound card, First Watt F1J diy clone power amp and HiFiMan HE-6 headphones. Without the DCB1, sound seems a bit more transparent and tight, but lacking some of the "body" and naturalness the DCB1 brings to the table. No free lunch
Finished building my hot rod, balanced DCB1 based on Tea-Bag's kit. Both DCB1's mounted to the same Modu 4 U 400 mm heatsink, temperature seems to be approx. 37 deg C. Using 3R3 CCS resistors, I'm measuring ~2 V across CCS resistors.
The DCB1 certainly seems to bring it's own flavor to the sound. More relaxed and "analog" presentation, maybe due to some added 2nd order distortion.
My setup is a LynxTwo-B sound card, First Watt F1J diy clone power amp and HiFiMan HE-6 headphones. Without the DCB1, sound seems a bit more transparent and tight, but lacking some of the "body" and naturalness the DCB1 brings to the table. No free lunch
Happy listening.
Power on my DCB1 build today.
Bought boards and matched mosfets from Tea-Bag an the rest from Hificollective and Elfa (Scandinavian version of Mouser)
Homemade copper heatsink 1mm thick at 180 x 240mm stock size giving it an aerea at about 390cm2 (60in2),
The copper heatsink seam to work quite well and the heat distributes well far away from the mosfets.
Takman carbon and metalfilm along with Mills 5w 10r.
Running at + 170ma shunt now and 40 deg C on the mosfets (and apox 37 deg on the sink)
Im using a 2x18vac 120VA R-core witch runs at 19.85vac with load giving me 26,4vDc after rectification.
No wonder the the series mosfets gets hotter than the parallel mosfet , having to drop 15 V.
I guess i should lowered the AC or put a CRC in front of the reg. to drop some more voltage?
I guess the rules applies that the regulator needs a minimum of 5-6volts over the reg.?
The numbers are as follows:
Some difference between the positive and negative i guess i need to play around with led to make the voltages equal
positive negative
10ohm CCR resistor 1,87 1,72
1ohm resistor mv 6,4 6,5
AC voltage in 19,87 19,86
DC voltage out of rectifier 26,4 26,48
DC voltage out of regulator 9,89 9,81
Voltage over 5 string led 9,23 9,16
Voltage over 3 string led 5,63 5,53
Bought boards and matched mosfets from Tea-Bag an the rest from Hificollective and Elfa (Scandinavian version of Mouser)
Homemade copper heatsink 1mm thick at 180 x 240mm stock size giving it an aerea at about 390cm2 (60in2),
The copper heatsink seam to work quite well and the heat distributes well far away from the mosfets.
Takman carbon and metalfilm along with Mills 5w 10r.
Running at + 170ma shunt now and 40 deg C on the mosfets (and apox 37 deg on the sink)
Im using a 2x18vac 120VA R-core witch runs at 19.85vac with load giving me 26,4vDc after rectification.
No wonder the the series mosfets gets hotter than the parallel mosfet , having to drop 15 V.
I guess i should lowered the AC or put a CRC in front of the reg. to drop some more voltage?
I guess the rules applies that the regulator needs a minimum of 5-6volts over the reg.?
The numbers are as follows:
Some difference between the positive and negative i guess i need to play around with led to make the voltages equal
positive negative
10ohm CCR resistor 1,87 1,72
1ohm resistor mv 6,4 6,5
AC voltage in 19,87 19,86
DC voltage out of rectifier 26,4 26,48
DC voltage out of regulator 9,89 9,81
Voltage over 5 string led 9,23 9,16
Voltage over 3 string led 5,63 5,53
An externally hosted image should be here but it was not working when we last tested it.
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Thanx, this is R-cores from Indian manufacturer Shilchar. i bought them from Selectronic
I purchased a load of these some years ago and after this project i have used them all.
Previously i have been purchasing toroids from toroidy.pl. nice and quiet transformers
I purchased a load of these some years ago and after this project i have used them all.
Previously i have been purchasing toroids from toroidy.pl. nice and quiet transformers
Your measurements are good. Is DC offset across the audio outputs acceptably low too?
If the total heat on the copper area (especially under the board not to work the components like resting over a frying pan) is still low enough, the 15V across series MOSFETS may stay. Helps them to lower parasitic capacitance even, if tolerable.
Thank you Salas.
Have 0V on the LH output and -1,5mV on the H chanennel with open inputs.
Will try more current later, i guess the sink can take more heat.
At the moment the series mosfets are running at 41-42 (body temperature)
When measuring at the copper under the in-between the mosfets its about 37-38 deg.
I guess the Kapton insulator and 2mm aluminum spacers along with copper screws helps the heat transferrer.
Have 0V on the LH output and -1,5mV on the H chanennel with open inputs.
Will try more current later, i guess the sink can take more heat.
At the moment the series mosfets are running at 41-42 (body temperature)
When measuring at the copper under the in-between the mosfets its about 37-38 deg.
I guess the Kapton insulator and 2mm aluminum spacers along with copper screws helps the heat transferrer.