O.T Electronics anyone?

A place to talk about whatever Scope music/gear related stuff you want.

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Neutron
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Post by Neutron »

Does anyone here build their own gear? I know a few musicians like to, to save money and to have exactly what they want.
I have some electronics experience, so i decided to build some mic preamps using these.

http://www.mil-media.com/docs/products/mm99.shtml

I am thinking of using battery power for low noise. anyone had any experience with them?

cheers
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eliam
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Post by eliam »

I've been thinking about this issue lately... A mic preamp would definitely be something I'd be willing to build myself.

How do you plan to do this?
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garyb
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Post by garyb »

go for it if you're so inclined!it should be easy to copy a nice design from a schematic.i'm sure there are many good designs around.(some of the most popular high end pre's are tube and are over 35 years old and more.no secrets there!)
ohmelas
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Post by ohmelas »

Pulsar continues to inspire in so many ways doesn't it?
:smile:

I've thought a lot about this issue lately myself. I was recently in the market for some isolation boxes and when I rudely discovered how much they really cost in a pre-fabricated sense, I wasn't about to not feed my family---so I built them with my father-in-law using the same specs.

All is well that ends well and if you're in the know with the lectronic cicruits then by all means go for it. I was looking to actually get on with some baby steps...when will creamware offer their DP platform? I'd like to make some of my own plugs.
Howard Salter Dot Com
Musician, Marine Corpsman, and Father
Milwaukee, WI USA
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Neutron
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Post by Neutron »

well the JFET amplifier modules are made by one of the respected high end pre amp manufacturers (millennia)

From what i gather they are a complete pre amp with only the addition of a feedback pot and resistor (gain) and i want as little else in the circuit as possible. (actually someone else is selling a kit with those modules and a power supply module)

they only use 50milliamps per channel, so i will power them with 4x 9v batteries (+-18v), with a relay in the circuit, so when the unit is turned off the batteries will charge.

that way there will be no chance of any spikes or line noise getting into the signal path.

the rest of the circuit (vu meters, leds etc) will be powered by a regular transformer -rectifier-smoothing capacitor power supply.

there are cool round LED meters that will go around the level pot just like a neutron synth :smile:
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garyb
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Post by garyb »

hope they sound good!
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Fede
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Post by Fede »

I've been buiding a balanced line input recently with a standard instrumentation amplifier circuit (3 amp-ops) for my guitar (that is balanced too).
Same thing in the mic preamp, plus providing phantom power
I saw the main problem is the S/N ratio of amp-ops, look for good quality ones.
JFET input amps (like TL07x family) aren't so noiseless, although have an high input impedance compared to BJTs, same thing for MOS's whose input capacitance is something similar to a microphone for noise and RFI only...
Tip: stabilization circuitry for alimentation with zener diode and transistor or switching circuitry
Good Luck
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