I am thinking about building a mic preamp for my CAD E-100 and was looking for some advice. First, I'd like to use mostly spare parts which I have an abundance. I already have power supply considerations taken care of. Right now I'm trying to decide between using tl074s or 4558s which I have an abundance of. I also have TA75064s and 1458s which neither seem to be up to the task. I would like to use op amps to simplify my design. I am a novice in analog design so any help would be great.
Look into getting a few INA217 or That 1512 IC"s....
They are Mic preamp Ic"s that sound very good and are super easy to build with, you can probably get them for $3-$5 a piece....
You can make a ballanced Input preamp with One DIP8 chip and about a dozzen extra parts (Minus PSU) on a PCB a couple inches square.....
I have built several and I use them all the time in my studio....
Cheers
They are Mic preamp Ic"s that sound very good and are super easy to build with, you can probably get them for $3-$5 a piece....
You can make a ballanced Input preamp with One DIP8 chip and about a dozzen extra parts (Minus PSU) on a PCB a couple inches square.....
I have built several and I use them all the time in my studio....
Cheers
Seconded.
The fet input opamps like the 074 are poorly suited to being driven from low impedance sources (far too much voltage noise), and while you could do something involving external transistors, a chip designed as a mic preamp is a better bet.
You will want to pay attention to the datasheet circuit for protecting the inputs from phantom power accidents as a hundred uf or so of cap at 48V suddenly being discharged into an IC input can degrade it.
Have fun.
Regards, Dan.
The fet input opamps like the 074 are poorly suited to being driven from low impedance sources (far too much voltage noise), and while you could do something involving external transistors, a chip designed as a mic preamp is a better bet.
You will want to pay attention to the datasheet circuit for protecting the inputs from phantom power accidents as a hundred uf or so of cap at 48V suddenly being discharged into an IC input can degrade it.
Have fun.
Regards, Dan.
Minion:
I've noticed your posts here and at Home Recording on the mic preamps that you've built. I'm looking to build something cheap for starters. Is it possible to get a copy of the schematics that you settled on for the preamp and power supply? PCB designs would be nice but not necessary - I could go from the schematics.
I'm not that great with electronics but can read schematics. I'm aware of the mic preamp schematic for the IAN217 that TI publishes, but have read at various sites on the internet of various modifications that folks have suggested, and either get lost with some of them, or they're just suggestions and not necessarily tested.
It sounds like you've arrived at a design through effort on several preamps.
Any help would be greatly appreciated.
I've noticed your posts here and at Home Recording on the mic preamps that you've built. I'm looking to build something cheap for starters. Is it possible to get a copy of the schematics that you settled on for the preamp and power supply? PCB designs would be nice but not necessary - I could go from the schematics.
I'm not that great with electronics but can read schematics. I'm aware of the mic preamp schematic for the IAN217 that TI publishes, but have read at various sites on the internet of various modifications that folks have suggested, and either get lost with some of them, or they're just suggestions and not necessarily tested.
It sounds like you've arrived at a design through effort on several preamps.
Any help would be greatly appreciated.
The actual Power supply I use is the same one used in the "Green Pre" which is also simular to the "Five fish" power suply and many others...It uses the Basic Datasheed implementation of the LM317/337 regulators and use a voltage tripler and a lm317 for the Phantom power....
For the Life Of me I can not find a schematic or PCB design for the PSU but I"m sure there is a schematic for the five fish PSU at there web site.....
as for the INA217 I have setteled on a pretty basic implementation , no Ballanced outs, No DC servo...Just go by the datasheet schematic and implement the features you want and omit the ones you don"t....Remember to use a good quality output cap (about 470uF) if not useing the DC Servo....
Without the DC servo and Ballanced outs you can make a PCB that is extremely small.....
Cheers
PS: this PSU schematic is very close to the one I use accept I use the LM317/337 regs and not the LM7XXX series regs...
For the Life Of me I can not find a schematic or PCB design for the PSU but I"m sure there is a schematic for the five fish PSU at there web site.....
as for the INA217 I have setteled on a pretty basic implementation , no Ballanced outs, No DC servo...Just go by the datasheet schematic and implement the features you want and omit the ones you don"t....Remember to use a good quality output cap (about 470uF) if not useing the DC Servo....
Without the DC servo and Ballanced outs you can make a PCB that is extremely small.....
Cheers
PS: this PSU schematic is very close to the one I use accept I use the LM317/337 regs and not the LM7XXX series regs...
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Hi Minion,
this Puwer Supply Schematic is pretty exactly what I'm looking for, only that I need +/-15V instead of +/-18V.
So I'm wondering if I could use a Transformer with 18V secondary output(and adjust the voltage regulators) instead of 20 in the schematic and still be able to get the 48V... Or would I have to change other Parts/values as well?
this Puwer Supply Schematic is pretty exactly what I'm looking for, only that I need +/-15V instead of +/-18V.
So I'm wondering if I could use a Transformer with 18V secondary output(and adjust the voltage regulators) instead of 20 in the schematic and still be able to get the 48V... Or would I have to change other Parts/values as well?
Hi all
First post here - sorry to resurrect an old thread.
I am new to DIY electronics, so my knowledge is limited. I need to build a power supply that can do 48V phantom and +/- 15 volts for an 8-channel SSI mic/line mixer that I rescued from the trash heap of a local studio.
It has 8 Melcor 1731 opamps for the channel mic in's and 6 more driving the line outs (I think).
Would the schematic above provide enough juice for that purpose? It's been a long time since I have taken an electronics class, but I think it is OK to have more amperage available than the circuits will need. Is this the case or am I mis-remembering? Would a pre-built supply such as this be a better way to go?:
LNR SUP DBL OUT 12-15V CASE E - HDD15-5-AG
I will also need a 24 V supply for the meter lights, but that is not really critical to get this thing working.
I have attached some pictures, if that would be helpful. First is from the bottom looking at mic/line inputs, second is front, third is from the top looking in, last is the rear panel.
Thanks much in advance for any insights you may have.
First post here - sorry to resurrect an old thread.
I am new to DIY electronics, so my knowledge is limited. I need to build a power supply that can do 48V phantom and +/- 15 volts for an 8-channel SSI mic/line mixer that I rescued from the trash heap of a local studio.
It has 8 Melcor 1731 opamps for the channel mic in's and 6 more driving the line outs (I think).
Would the schematic above provide enough juice for that purpose? It's been a long time since I have taken an electronics class, but I think it is OK to have more amperage available than the circuits will need. Is this the case or am I mis-remembering? Would a pre-built supply such as this be a better way to go?:
LNR SUP DBL OUT 12-15V CASE E - HDD15-5-AG
I will also need a 24 V supply for the meter lights, but that is not really critical to get this thing working.
I have attached some pictures, if that would be helpful. First is from the bottom looking at mic/line inputs, second is front, third is from the top looking in, last is the rear panel.
Thanks much in advance for any insights you may have.
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