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Salas DCG3 preamp (line & headphone)
Salas DCG3 preamp (line & headphone)
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Old 28th February 2017, 11:01 AM   #1471
MagicBus is offline MagicBus  Greece
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Agreed. That's why I think XLR pin 1 sould be connected to circuit GND in this case. I'll test it against pin 1 connected to chassis as soon as I find some time.
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Old 28th February 2017, 11:26 AM   #1472
bkdog is offline bkdog
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Salas DCG3 preamp (line & headphone)
XLR pin 1 must be connected to the chassis by the shortest route. Please do a search for "pin 1 problem". I think Rane had a decent analysis of the issues when I last looked.
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Old 28th February 2017, 11:28 AM   #1473
ivigueras is offline ivigueras  Spain
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Salas DCG3 preamp (line & headphone)
Hello!

Salas, I'm thinking about to try some better resistors like Shinkoh that I like very much in my DCB1, but are expensive. What resistors do you think are more critical in the signal path? (R1, R15 and RZJ, evidently)

Thanks!
Ignacio.
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Old 28th February 2017, 11:34 AM   #1474
MagicBus is offline MagicBus  Greece
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This is true for differential amps. Here we have two indepented lines that do not amplify the difference of the signals applied in their inputs but just amplify the antiphase signals they get from the source. In differential amps the circuit ground stays out of the line. In the application discussed here the circuit ground is the returning path af the signal as with all SE circuits
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Old 28th February 2017, 01:09 PM   #1475
Salas is offline Salas  Greece
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Salas DCG3 preamp (line & headphone)
Quote:
Originally Posted by ivigueras View Post
Hello!

Salas, I'm thinking about to try some better resistors like Shinkoh that I like very much in my DCB1, but are expensive. What resistors do you think are more critical in the signal path? (R1, R15 and RZJ, evidently)

Thanks!
Ignacio.
R6, R7 (feedback) for sure are important

R4, R5 (gate stoppers) are in the signal path also
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Old 28th February 2017, 01:24 PM   #1476
Salas is offline Salas  Greece
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Salas DCG3 preamp (line & headphone)
Quote:
Originally Posted by MagicBus View Post
This is true for differential amps. Here we have two indepented lines that do not amplify the difference of the signals applied in their inputs but just amplify the antiphase signals they get from the source. In differential amps the circuit ground stays out of the line. In the application discussed here the circuit ground is the returning path af the signal as with all SE circuits
Can alternatively lift from GND and connect the phase channel amps R7 feedback returns together
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Old 28th February 2017, 02:18 PM   #1477
nashbap is offline nashbap  United States
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2) You will only need one CL60 per DCG3 board. It could be connected like my ground lifters - the rectifier bridge with the power resistor and the cap.

Thanks for responding Kostas.

So is your SLB connected to the DCSTB G point? I see that it is next to it.

nash
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Old 28th February 2017, 02:25 PM   #1478
nashbap is offline nashbap  United States
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Quote:
Originally Posted by MagicBus View Post
This is true for differential amps. Here we have two indepented lines that do not amplify the difference of the signals applied in their inputs but just amplify the antiphase signals they get from the source. In differential amps the circuit ground stays out of the line. In the application discussed here the circuit ground is the returning path af the signal as with all SE circuits
Kostas, I thought that you mentioned that you had a balanced connection going into your DCG3 from your DAC. In which case you should have signal between pins 2 and 3 only, not between pin 2 and pin1 and pin 3 and pin 1, since pin 1 is only the shield. I am referring to the XLR plug that plugs into the XLR connector of the DCG3.

nash
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Old 28th February 2017, 04:51 PM   #1479
MagicBus is offline MagicBus  Greece
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Quote:
Originally Posted by Salas View Post
Can alternatively lift from GND and connect the phase channel amps R7 feedback returns together
Yes, I ought to test this at some point. It would change the way I can connect DCG3 for balanced or SE mode though.
Quote:
Originally Posted by nashbap View Post
2) You will only need one CL60 per DCG3 board. It could be connected like my ground lifters - the rectifier bridge with the power resistor and the cap.

Thanks for responding Kostas.

So is your SLB connected to the DCSTB G point? I see that it is next to it.

nash
SLB is connected midway to the wire from DCG3 to DCSTB
Quote:
Originally Posted by nashbap View Post
Kostas, I thought that you mentioned that you had a balanced connection going into your DCG3 from your DAC. In which case you should have signal between pins 2 and 3 only, not between pin 2 and pin1 and pin 3 and pin 1, since pin 1 is only the shield. I am referring to the XLR plug that plugs into the XLR connector of the DCG3.

nash
DAC output is balanced but circuit GND is connected to chassis by default and consequently so is pin 1 coming out from it though I suspect the sound card incorporates some kind of SLB too. Pin 2 and 3 carry the signal. Typical so far. Now, DCG3 input pin 1 could be connected to chassis or circuit GND without altering the grounding scheme of the DAC - sound card. Actually, when DCG3 runs on balanced mode it doesn't need the SLBs. It needs them only in SE mode. But even in balanced mode - if we don't do the R7 modification - DCG3 works in SE mode and then pin 1 is in the circuit.
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Old 28th February 2017, 06:24 PM   #1480
ernesternest is offline ernesternest  Europe
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Hello Salas, hello Tea, another DCG3 running :-)

Thank you both and all the other guys too for their questions which prevented me from asking ;-)
Here my build still in workshop running on 130 mA and 6mV DC at output without the service.

Click the image to open in full size.

Last edited by ernesternest; 28th February 2017 at 06:27 PM.
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