Well not exactly a DI as it will not be provided any source of phantom power...
In a nutshell I want a single channel line stage buffer with switch selectable gains 6,12,@18dB.
Normal input would be -10dBv via cinch, but an XLR in would be nice too.
Seeing as XLR input would be +4dBu and I want an +18db gain option and some headroom left I'll need roughly 48V p-p - I think?
😱
I'm not familiar with what's out there so I'm asking here 😀
What say you?
Thanks 🙂
In a nutshell I want a single channel line stage buffer with switch selectable gains 6,12,@18dB.
Normal input would be -10dBv via cinch, but an XLR in would be nice too.
Seeing as XLR input would be +4dBu and I want an +18db gain option and some headroom left I'll need roughly 48V p-p - I think?
😱I'm not familiar with what's out there so I'm asking here 😀
What say you?
Thanks 🙂
Could explain what a DI box is and does?
And what is different in your application?
+22dBu is 9.75Vac, or about 28Vpp
You can get that from a rail to rail opamp on +-16Vdc. But you'd do far better avoiding all the rail to rail opamps and use +-18Vdc to +-24Vdc. A discrete circuit capable of driving a 1k load would need a current capability of ~18mA.
Add on a further 10mA for capacitive cable loading and you are still in the region that can be supplied by an opamp.
A composite opamp + buffer as described by Jung?
And what is different in your application?
+22dBu is 9.75Vac, or about 28Vpp
You can get that from a rail to rail opamp on +-16Vdc. But you'd do far better avoiding all the rail to rail opamps and use +-18Vdc to +-24Vdc. A discrete circuit capable of driving a 1k load would need a current capability of ~18mA.
Add on a further 10mA for capacitive cable loading and you are still in the region that can be supplied by an opamp.
A composite opamp + buffer as described by Jung?
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Hi Andrew,
DI stands for direct injection, commonly used as a preamp between an instrument like a guitar and the mixer. Some DI boxed actually get power via 48v phantom power provided from the mixer that the DI box is connected to.
In my application none of that applies, I just need a single channel of quality preamp conversion to balanced interface.
Actually After I posted this I went on to find exactly the type of device I am looking for, except for the $200 usd cost and a couple extra features I was not looking for it looks good. And it has +-18V capability...
SC-1mk3 Mic Preamp
Anyone heard of these guys? Any opinions?
Thanks
DI stands for direct injection, commonly used as a preamp between an instrument like a guitar and the mixer. Some DI boxed actually get power via 48v phantom power provided from the mixer that the DI box is connected to.
In my application none of that applies, I just need a single channel of quality preamp conversion to balanced interface.
Actually After I posted this I went on to find exactly the type of device I am looking for, except for the $200 usd cost and a couple extra features I was not looking for it looks good. And it has +-18V capability...
SC-1mk3 Mic Preamp
Anyone heard of these guys? Any opinions?
Thanks
This is a mic pre-amp with a maximum gain of +72dB
You are looking for a line driving pre-amp with gains (switchable) of +6dB to +18dB
If you want unbal to balanced, there are chips specifically made for this duty.
You are looking for a line driving pre-amp with gains (switchable) of +6dB to +18dB
If you want unbal to balanced, there are chips specifically made for this duty.
I know what it is 😀
Although it has up to 72dB gain it is still only +-18V capable... Kind of a moot point IMO.
The switchable gain settings and gain trim is nice as is phase inversion... If it were half the cost I'd accept it's short comings and ignore that it was ever intended to be a mic pre 😀
What about the conversion chip??? Sounds interesting.
Although it has up to 72dB gain it is still only +-18V capable... Kind of a moot point IMO.
The switchable gain settings and gain trim is nice as is phase inversion... If it were half the cost I'd accept it's short comings and ignore that it was ever intended to be a mic pre 😀
What about the conversion chip??? Sounds interesting.
Andrew we did this one year ago!
http://www.diyaudio.com/forums/analog-line-level/195507-di-box-question.html
http://www.diyaudio.com/forums/analog-line-level/195507-di-box-question.html
Remember that in this context, the -10dBV and +4dBu are 0VU levels and *not* peak outputs. You'll need to allow for at least 14dB and preferably 20dB for peaks, plus a little headroom. (And this has nothing to do with a DI box.)
All good fortune,
Chris
All good fortune,
Chris
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