I am wondering about that as well. Is there a need to invert the signal. Perhaps that messes with the amp stability.
On the other hand, if the non-inverting configuration is selected, there should be have no surprises.
I know nothing about panning but I noticed a circuit in the 4562 and snapped it.
Please ignore if it is not relevant.
Please ignore if it is not relevant.
I use my DAC's volume control and DAC output directly to amp. No noise no hiss.
My DAC noise is less than -120dBV and amp noise is around 60uV to 80uV, which make my amp the dominant noise contributor.
My DAC noise is less than -120dBV and amp noise is around 60uV to 80uV, which make my amp the dominant noise contributor.
Jason's reply reminded me of something. So far we're all assuming it is normal circuit noise (thermal, shot, 1/f) of your circuit, but it could also be intermodulation between ultrasonic quantization noise components coming out of your phone, or just audio noise of your phone.
For the same gain and treble settings, do you get roughly the same noise floor with the input shorted and with the input connected to your phone?
Luckily it is easy to find in pdf 🙂
That circuit would be usefull for converting a mono input into a paned stereo.
But what i was thinking of was some way to convert from stereo input to a "re-paned stereo" output.
Folks should correct the signs of the lower op amp before building that one ...
Ok i drew a new schematic:
(Output of mic stage goes into the left input of the preamp) // (strange feedback pots in VOL and AUX circuits are made this way to make log response out of linear potentiometers, found this on "small signal audio design" douglas self)
Mic iput circuit (The only circuit I found that would have good results while mantaining low component count)
Baxandall
Changes:
-Lower resistor values
-mic/line/stereo-in altogether in the same channel strip (i got some combo XLR/6,5stereo jacks)
-Balance control that doesnt fry baxandall opamp output
-Only uses 10k linear pots (instead of 100k log, 500k lin, 100k lin, etc... ), reducing noise and making pots easier to find
Issues:
-Preamp gain control is linear
-extra opamp u6B without use
I could build a peak detector out of U6B, but it would be uni-ploar, as I havent found any circuit that senses both + and - peaks using only one opamp...
I will first build the mic stage and line preamp circuits separately. To see how much "noiseless" they can get. Then if those have good results I will continue and build the rest
But before that, any circuit advice/changes before starting?
(Output of mic stage goes into the left input of the preamp) // (strange feedback pots in VOL and AUX circuits are made this way to make log response out of linear potentiometers, found this on "small signal audio design" douglas self)
Mic iput circuit (The only circuit I found that would have good results while mantaining low component count)
Baxandall
Changes:
-Lower resistor values
-mic/line/stereo-in altogether in the same channel strip (i got some combo XLR/6,5stereo jacks)
-Balance control that doesnt fry baxandall opamp output
-Only uses 10k linear pots (instead of 100k log, 500k lin, 100k lin, etc... ), reducing noise and making pots easier to find
Issues:
-Preamp gain control is linear
-extra opamp u6B without use
I could build a peak detector out of U6B, but it would be uni-ploar, as I havent found any circuit that senses both + and - peaks using only one opamp...
I will first build the mic stage and line preamp circuits separately. To see how much "noiseless" they can get. Then if those have good results I will continue and build the rest
But before that, any circuit advice/changes before starting?
Sorry, this thing is junk. I don't even want to know the EIN levels... there's no way they're remotely close to what you need for a decent dynamic microphone preamp (which is all this one could do for lack of phantom power). If you need low component count, take a look at dedicated preamp ICs like THAT1510/1512, as used by ThatMicPre. Also see "the $5 mic preamp". Cheap audio interfaces are apparently beating an NJM2122 into submission, which I assume is involving external compensation... not for noobs.
Behringer mixers are using a variation on P66, with - I think - a voltage tripler to get the (AC) power supply input voltage high enough for a proper +48 V phantom power supply (USB jobs are using little switch-mode DC/DC converters instead). Only a few very cheap ones are directly requisiting +15V instead, at which point I imagine you'll also want to adapt the standard 6k8 resistors for a better chance of mics working properly.
Your AUX out and PAL / VOL circuits are likely to suffer from scratchy pots sooner rather than later, and you can ask Musical Fideity A1 owners about the long-term reliability of "pot in feedback" circuits as in your line preamp (incidentally, feedback network impedance levels are a tad low there now, I would up these by about a factor of 3 again). Spoiler: not great.
I´ll use THAT. (kind of a rare ic in my country)
As for the panpot, coupling capacitors at the baxandall output
And no more feedback pots.
Thank you, surely when I started this I thought there were less variables/things to take into account for...
As for the panpot, coupling capacitors at the baxandall output
And no more feedback pots.
Thank you, surely when I started this I thought there were less variables/things to take into account for...
I have a crazy question....5532s with no compensation caps across Rf? Are you sure the outputs are not oscillating at some high freq?
Oh and panning...its kind of important that the sum when panned to the center is equal to the level if panned full left or right.
http://www.geofex.com/Article_Folders/panner.pdf
http://www.geofex.com/Article_Folders/panner.pdf
thanks for the link!, Useful circuits.
I didn't hear anything, but it could have ultrasonic oscillations...
I thought about an old databook I used to rely on from National Semiconductor called "The Audio Handbook" and low and behold I found a PDF on the web..you might enjoy..lots of cool stuff for us nerds.
http://bitsavers.trailing-edge.com/components/national/_dataBooks/1976_National_Audio_Handbook.pdf
http://bitsavers.trailing-edge.com/components/national/_dataBooks/1976_National_Audio_Handbook.pdf
My experience is related to making tube based preamps.
For the lowest noise, I use an external power supply, DC heaters, and SMPS based PSU. I'm of the school that even with all the gain in the world, a preamp playing nothing should be silent at full blast, and I have accomplished this but only using external PSU.
Since you posted in the solid state area, I suggest using batteries for the lowest noise. A pair of 9V batteries gives 18V which is more than enough for the output of a pre I think.
For the lowest noise, I use an external power supply, DC heaters, and SMPS based PSU. I'm of the school that even with all the gain in the world, a preamp playing nothing should be silent at full blast, and I have accomplished this but only using external PSU.
Since you posted in the solid state area, I suggest using batteries for the lowest noise. A pair of 9V batteries gives 18V which is more than enough for the output of a pre I think.