Hi,
I' ve checked again for SE in/bal out conversion in my built. R7 to ground, xlr pin1 to chassis, -in to ground, 10 ohm DCR ground lifters. I used audacity to feed DCG3 with 50Hz sinewave and measured the output with DMM set to AC. No, there is not balanced output with SE input. I got 32mV at +out, 0V at -out and 32mV accross +out and -out.
I' ve checked again for SE in/bal out conversion in my built. R7 to ground, xlr pin1 to chassis, -in to ground, 10 ohm DCR ground lifters. I used audacity to feed DCG3 with 50Hz sinewave and measured the output with DMM set to AC. No, there is not balanced output with SE input. I got 32mV at +out, 0V at -out and 32mV accross +out and -out.
RZ/J watt rating
Planning to put in 10 ohm resistors in RZ/J (250 ohm headphones). Do the resistors need to be rated for 1 watt, or it's possible to use lower wattage also?
I have the following post made by Salas for reference:
http://www.diyaudio.com/forums/anal...cg3-preamp-line-headphone-17.html#post4846693
The post states - " It must be 1W when of substantial value intentionally used " - I am not sure if 10 ohms is substantial value in this case.
Planning to put in 10 ohm resistors in RZ/J (250 ohm headphones). Do the resistors need to be rated for 1 watt, or it's possible to use lower wattage also?
I have the following post made by Salas for reference:
http://www.diyaudio.com/forums/anal...cg3-preamp-line-headphone-17.html#post4846693
The post states - " It must be 1W when of substantial value intentionally used " - I am not sure if 10 ohms is substantial value in this case.
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5Vac into 250ohms + 10r draws ~ 19.2mAac
The headphones can draw transient current that may approach 150% of the resistor equivalent load. That gives the maximum peak current = 1.5*sqrt(2)*19.2mA = ~40.8mApk
Passing that into a 10r resistor using the standard formula P = I^2R gives an instantaneous peak dissipation of 16.6mW
Why can't Members just rely on the arithmetic instead of guessing?
BTW,
that 5Vac into 250ohms is equivalent to +20dBmW, ear drums still recovering an hour later !
The headphones can draw transient current that may approach 150% of the resistor equivalent load. That gives the maximum peak current = 1.5*sqrt(2)*19.2mA = ~40.8mApk
Passing that into a 10r resistor using the standard formula P = I^2R gives an instantaneous peak dissipation of 16.6mW
Why can't Members just rely on the arithmetic instead of guessing?
BTW,
that 5Vac into 250ohms is equivalent to +20dBmW, ear drums still recovering an hour later !
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Unfortunately certain members (like myself) have limited knowledge of circuits and electronics - hence was not able to connect the dots together to do the calculation. Now that you've explained it, seems simple...
Ouch!
Is it for beyerdynamic 250 Ohm headphones?
I suggest you first put socket pins for Rz like those the IC sockets have. So you can try various Rz values and decide. 10 Ohm for a 250 Ohm headphone load will certainly buffer the long cable's pF better but not sure it can noticeably alter the transducer's frequency balance.
I suggest you first put socket pins for Rz like those the IC sockets have. So you can try various Rz values and decide. 10 Ohm for a 250 Ohm headphone load will certainly buffer the long cable's pF better but not sure it can noticeably alter the transducer's frequency balance.
Yes sir, it is none other. Beyerdynamic DT880.
Thank you for the suggestion. Something like this should work?
http://www.digikey.com/products/en?mpart=8730&v=36
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I can only do simple arithmetic. That's probably why I will never become, nor even attempted to try EE training and went for Civil Engineering and not even Structural. Again they need high power mathematics and an ability to see the route to an answer very quickly.
Having the Forth Bridge and the Forth Road bridge nearby, I am aware of the jobs of those Structural Engineers and what they can do economically.
Now I get to watch the construction of the third crossing of the east Forth and stand in awe at what modern technologies are achieving.
And we have the Kincardine Bridge. The longest swing bridge in Europe at the time of it's opening c 1937.
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Very good model. Takes + $400 for really better from Beyer (DT1990)
You could try various Rz by 10 Ohm step maybe up to 1/4 nominal for curiosity. The 880 is among their smoother along 770/80, but less V shaped, still has that 10kHz peak nonetheless which can sting when excited on some genres / tracks.
I mean header pins you can cut from a row like 310-87-104-41-001101 Preci-Dip | Connectors, Interconnects | DigiKey
Thank you Salas - will try out as advised.
Btw, I am using the DCG3 on a daily basis as a line preamp and enjoying - thank you for sharing this with the DIY Community!
And on a side note, I also like the warm glow of the LEDs. My case is still without a top - will have to plan for incorporating an acrylic window on the top so that parts of the power supply unit are still visible.
Hmmm... nice!
Btw, I am using the DCG3 on a daily basis as a line preamp and enjoying
- thank you for sharing this with the DIY Community!And on a side note, I also like the warm glow of the LEDs.
My case is still without a top - will have to plan for incorporating an acrylic window on the top so that parts of the power supply unit are still visible.Hmmm... nice!
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Thank you Salas - will try out as advised.
Btw, I am using the DCG3 on a daily basis as a line preamp and enjoying
And on a side note, I also like the warm glow of the LEDs.
Hmmm... nice!
I also would have done some acryllic stuff, for the look at the nice PSU's inside
... I never did that work through!I like to still follow this thread, looking at peoples marveles builds, and chassis.
Anyway, i am done with my winther project's for now, gathering information and like for next winther build.. What are you guy's using for DAC's here?
It might be, that i am building an Soekris DAM1021 for a freind... That way i can listning at that particulair R2R-DAC my Danish fellow developed some years back.
Please keep posting pictures of the DCG3 build
Jesper.
I also would have done some acryllic stuff, for the look at the nice PSU's inside
I like to still follow this thread, looking at peoples marveles builds, and chassis.
Anyway, i am done with my winther project's for now, gathering information and like for next winther build.. What are you guy's using for DAC's here?
It might be, that i am building an Soekris DAM1021 for a freind... That way i can listning at that particulair R2R-DAC my Danish fellow developed some years back.
Please keep posting pictures of the DCG3 build
Jesper.
For Dac, i am using diy ak4490 ( single side pcb )
More on SE input to balanced output conversion;
I checked with R7s lifted. Yes, it does SE/bal conversion. The interesting thing is that it does it with and without - in to GND! Also there is buzz noise not affected by ground lifters. It doesn't change to better or worse even if I touch the wire that connects the R7s. Go figure!
Pic of my "DAC". A modified Asus essense STXII.
I checked with R7s lifted. Yes, it does SE/bal conversion. The interesting thing is that it does it with and without - in to GND! Also there is buzz noise not affected by ground lifters. It doesn't change to better or worse even if I touch the wire that connects the R7s. Go figure!
Pic of my "DAC". A modified Asus essense STXII.
Attachments
It does it with and without - in to GND on the simulator also. For buzzes maybe it takes physical rearrangement of the grounding like separation of the plane between phases, also coaxial cable with one way shield grounding between R7s and grounding of - in. In general its not easy to create a very good se to bal converter out of physically well separated SE routes. Sends/returns must track along in tandem for narrow loop area. Best should be a dedicated se input to bal transformer or a chip for that job. Real bal in bal out needs modify nothing and its quiet as you know from your build.
I am thinking at some point to try the DCG3 with a pair of SSLV1.1 shunt regs which at the moment are supplying a BA3 preamp with +-24vdc. Would I be ok using the same transformers; 2x22vac secondaries which are giving 28vdc after the the main capacitors. This would mean dropping 11 volts. Also is 220R the correct load resistor for a dummy load? tia.