I would hope that the PEQ DIY planning and zoning committe don't swoop in because you're having too much fun. All hell would break loose if you sold one.
If there are build-out resistors used with the DCAO driving the Pultec filter network it would be interesting to see the drop across them vs. frequency and EQ settings.
The build-out is a current sense resistor and the point of lowest impedance (greatest shunt voltage) might be interesting to measure. You could use a 1240 across that resistor and look at the 1240 output or the 'scope in differential mode.
Dual Class-A Line and Headphone Output Board Construction Information
- mediatechnology
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- mediatechnology
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Re: Dual Class-A Line and Headphone Output Board
Figuring out how low the impedance actually goes might help us dial in Iq for that application.
I just noticed something in the PC board photo: There are only three resistors (per DCAO channel) that are actually in the signal path.
The MS Matrix only has two.
I just noticed something in the PC board photo: There are only three resistors (per DCAO channel) that are actually in the signal path.
The MS Matrix only has two.
- mediatechnology
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Re: Dual Class-A Line and Headphone Output Board Documents
Hey Guys,
I haven't checked in for a while. This board looks great. Great job as usual Wayne and Roger. I'll have to dig out the chip data sheets and try to figure out what all that fancyness is doing. I'm sure I can learn a lot by studying it.
Paul
I haven't checked in for a while. This board looks great. Great job as usual Wayne and Roger. I'll have to dig out the chip data sheets and try to figure out what all that fancyness is doing. I'm sure I can learn a lot by studying it.
Paul
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Re: Dual Class-A Line and Headphone Output Board Documents
Thanks for checking in Paul!
Re: Dual Class-A Line and Headphone Output Board Documents
This would be really nice as line preamp with gain for my mastering console. It needs to be able to drive multiple loads at once. It looks like there is plenty of room on the board to mount a daughter board with an opamp for gain. I don't mind an impedance balanced output. There wouldn't be enough room in the chassis to mount eight boards. Since I am no designer I would feel safer running the gain opamp in an inverting configuration. Could I flip the output polarity by reversing pins 1 & 8 on the DRV?
- mediatechnology
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Re: Dual Class-A Line and Headphone Output Board Documents
Thanks Paul.Could I flip the output polarity by reversing pins 1 & 8 on the DRV?
Actually you could just re-define the inputs at the THAT124X calling "-" "+."
If there was an inverting stage after the 124X producing gain the resulting double-inversion would give you an in-polarity output.
Re: Dual Class-A Line and Headphone Output Board Documents
I guess the word 'duh' applies here.mediatechnology wrote:Actually you could just re-define the inputs at the THAT124X calling "-" "+."Could I flip the output polarity by reversing pins 1 & 8 on the DRV?
- mediatechnology
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Re: Dual Class-A Line and Headphone Output Board Documents
I used it, in reference to myself, just yesterday.I guess the word 'duh' applies here.
Proud of it too. I earned it.
- mediatechnology
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Re: Dual Class-A Line and Headphone Output Board Documents
Thanks Roger!
What are the details e.g. primary impedance, build-out resistance, Cinemag model etc?
What are the details e.g. primary impedance, build-out resistance, Cinemag model etc?