I apologize if anything like this has come up here before or if my questions appear quite dumb but I'm new to this forum and somewhat new to electronics as well. I also apologize for the length of my post but I tried to include as much information as possible to better facilitate any responses to my post.
Anyway, I have a couple of 1588 Altec input modules which I have been using as mic pres for sometime. For the time being I've been connecting them to a 12volt wall wart and then to a xlr input jack and 1/4 output jack all via hook-up wire and allegator clips. Having no enclosure I usually just put the thing on a non-conductive surface and goto work. However, while the altecs aren't my goto pres, I do like them and was thinking about racking them up so I don't have to rig them up everytime I use them. Also I wanted to add phantom power and phase reversal to the pres and if possible a way to attenuate their gain (fixed 33db). In addition I wanted to put them in a proper rack mount enclosure with xlr inputs and 1/4 outputs.
Now for my questions:
1)I want to use 2 modules in one rack mounted enclosure, I was told that they need 40mA of power each and that I should power them via a 12v powersupply. I also want to add phantom power and if possible a pot or something to change the gain, hence I know my power supply requirements are going to be a bit more. I also want it to have an on/off on the front along with a LED that lights up when the unit is functioning. I want this to be a professional looking and operating unit and thus wanted to build a powersupply to do all this but have no idea where to start or how to design one. I have pretty good soldering skills (I've made tons of cables), I have done some basic work on guitars and amps, replacing pick-ups, replacing caps and installing 3-prong cables in old amps so I have a basic knowledge of electricity but don't know where to start when tackling this type of project having never built or designed anything electronics-wise in my life.
2)I have done some research on this and have found a bunch of schematics for phantom power circuts, could I just pick any of them and stick it before the input of the pre-amp module, basically how would I go about designing and encorporating phantom power into the pre?
3)As for the phase reversal, all I need to do is use a DPDT switch hooked up to pins 2 and 3 on the module's input right?
4)I like the existing tone of the module and don't wish to alter it drastically so I wanted to know what would be the most effective way to change the gain without altering the tone of the pre? Someone suggested I use something like an OP07 opamp, with a potentiometer in the feedback loop or a multi-stage gain switch to reduce noise and set up as an inverting amplifier, so I could change the gain by maybe +/-20dB but I don't fully comprehend what all of that means or how to go about implimenting it. If it would be to difficult to provide a way to change the gain I would skip this step and just run the output signal through other gear if I needed to make adjustments but I thought building it into the unit would be a nice touch.
5)I want to put this all in a nice rack mounted enclosure. I've heard plenty of people recommend par-metal. Looking over their site the stuff looks nice, I didn't expect things to be so expensive. My main problem is while I have a soldering iron, solder sucker, soldering braid, screw drivers and a whole bunch of other tools, I don't have a drill, certainly don't have a drill press nor the speciality bits necessary to do all the metal work involved in altering the enclosure to fit my needs. Hence, could somebody recommend a place either online or somewhere in my yellow pages I should look for that might do this work for me. I suppose if worst comes to worst I could borrow a drill and if its not to expensive buy some of the bits but seeing as I don't do a ton of this diy work I would rather not have to purchase any new tools.
Well, I think thats it. My apologies for being so wordy. I've been recording music for a long time and recently got the urge to start delving into the more technical aspects of gear and electronics and figured this might be a good place to start. Once again I'm sorry if any of this has been discussed here before but I would greatly appreciate any suggestions, links to other useful sites or book recommendatoins that would get me going. Thanks in advance all for your time and help.
Anyway, I have a couple of 1588 Altec input modules which I have been using as mic pres for sometime. For the time being I've been connecting them to a 12volt wall wart and then to a xlr input jack and 1/4 output jack all via hook-up wire and allegator clips. Having no enclosure I usually just put the thing on a non-conductive surface and goto work. However, while the altecs aren't my goto pres, I do like them and was thinking about racking them up so I don't have to rig them up everytime I use them. Also I wanted to add phantom power and phase reversal to the pres and if possible a way to attenuate their gain (fixed 33db). In addition I wanted to put them in a proper rack mount enclosure with xlr inputs and 1/4 outputs.
Now for my questions:
1)I want to use 2 modules in one rack mounted enclosure, I was told that they need 40mA of power each and that I should power them via a 12v powersupply. I also want to add phantom power and if possible a pot or something to change the gain, hence I know my power supply requirements are going to be a bit more. I also want it to have an on/off on the front along with a LED that lights up when the unit is functioning. I want this to be a professional looking and operating unit and thus wanted to build a powersupply to do all this but have no idea where to start or how to design one. I have pretty good soldering skills (I've made tons of cables), I have done some basic work on guitars and amps, replacing pick-ups, replacing caps and installing 3-prong cables in old amps so I have a basic knowledge of electricity but don't know where to start when tackling this type of project having never built or designed anything electronics-wise in my life.
2)I have done some research on this and have found a bunch of schematics for phantom power circuts, could I just pick any of them and stick it before the input of the pre-amp module, basically how would I go about designing and encorporating phantom power into the pre?
3)As for the phase reversal, all I need to do is use a DPDT switch hooked up to pins 2 and 3 on the module's input right?
4)I like the existing tone of the module and don't wish to alter it drastically so I wanted to know what would be the most effective way to change the gain without altering the tone of the pre? Someone suggested I use something like an OP07 opamp, with a potentiometer in the feedback loop or a multi-stage gain switch to reduce noise and set up as an inverting amplifier, so I could change the gain by maybe +/-20dB but I don't fully comprehend what all of that means or how to go about implimenting it. If it would be to difficult to provide a way to change the gain I would skip this step and just run the output signal through other gear if I needed to make adjustments but I thought building it into the unit would be a nice touch.
5)I want to put this all in a nice rack mounted enclosure. I've heard plenty of people recommend par-metal. Looking over their site the stuff looks nice, I didn't expect things to be so expensive. My main problem is while I have a soldering iron, solder sucker, soldering braid, screw drivers and a whole bunch of other tools, I don't have a drill, certainly don't have a drill press nor the speciality bits necessary to do all the metal work involved in altering the enclosure to fit my needs. Hence, could somebody recommend a place either online or somewhere in my yellow pages I should look for that might do this work for me. I suppose if worst comes to worst I could borrow a drill and if its not to expensive buy some of the bits but seeing as I don't do a ton of this diy work I would rather not have to purchase any new tools.
Well, I think thats it. My apologies for being so wordy. I've been recording music for a long time and recently got the urge to start delving into the more technical aspects of gear and electronics and figured this might be a good place to start. Once again I'm sorry if any of this has been discussed here before but I would greatly appreciate any suggestions, links to other useful sites or book recommendatoins that would get me going. Thanks in advance all for your time and help.
