Hi!, I am a musician that is looking for someone to build a custom mixer for my double bass.
I currently use 3 sources to get an amplified sound out of my instrument:
1) Condenser MIC (Shure PGA81)
2) Piezzo Pickups (Fishman BP-100)
3) Magnetic Pickup (Krivo Pickup for Upright Bass)
My project is to build a mixer, with volume and eq for each channel, that can output a balanced line level and a instrument level one. For the conndenser mic must also provide phantom power and the idea is that it should be portable.
Any tips who could build something like this would be much appreciated.
Thanks!
Johann
I currently use 3 sources to get an amplified sound out of my instrument:
1) Condenser MIC (Shure PGA81)
2) Piezzo Pickups (Fishman BP-100)
3) Magnetic Pickup (Krivo Pickup for Upright Bass)
My project is to build a mixer, with volume and eq for each channel, that can output a balanced line level and a instrument level one. For the conndenser mic must also provide phantom power and the idea is that it should be portable.
Any tips who could build something like this would be much appreciated.
Thanks!
Johann
Attachments
You don't need a custom mixer for that. Get an older analog mixing console (since they are way less expensive than digital ones, actually often dirt cheap) with subgroups. Put each of your sources on the same subgroup. With the faders of each channel/input from your instrument you can adjust the level and with the parametric or semi-parametric eq you can adjust each sound. The level of your instrument to the rest is then adjusted by the subgroup fader. You could also add effects or an external eq by the aux send/return, each of the inputs can be muted separately too if you want to switch back and forth.
Every mixer got a preamp for every separate channel. You can pre-adjust the level with the gain-knob. And ofcourse then adjust the level with the faders too.
You're mixing things up. 
The impedance doesn't have anything to do with a lowcut. Yes, mixers are built to handle both, many have, additional to the gain knob, a separate +20dB switch.
For the low cut: On many mixers you've got a 75Hz filter, which gets rid of many 'pop' sounds while singing and noises from handling instruments.
Well, how many channels do you need besides the 3 of your instrument?
The impedance doesn't have anything to do with a lowcut. Yes, mixers are built to handle both, many have, additional to the gain knob, a separate +20dB switch.For the low cut: On many mixers you've got a 75Hz filter, which gets rid of many 'pop' sounds while singing and noises from handling instruments.
Well, how many channels do you need besides the 3 of your instrument?
You're mixing things up.
For the low cut: On many mixers you've got a 75Hz filter, which gets rid of many 'pop' sounds while singing and noises from handling instruments.
Well, how many channels do you need besides the 3 of your instrument?
He's talking about using a piezo pickup into a mic preamp. You'll get a low-cut at around 2kHz IIRC.
Piezo pickups need an input impedance of at least 1Mohm to be useful, which usually mandates an external preamp.
Chris
Thanks. I've so far only encountered piezo pickups with built-in preamps, which don't behave much different from electret mics. Without one, it would indeed not work well, most mixers got an input impedance between 10-50k. I haven't thought about that. But there's a simple solution, on this page is a piezo preamp circuit that is so small, it could likely be included in the mixer and use the power supply of it. Or, if there's too little room for it, you could simply attach it with a velcro strip to the mixer.
Just a couple of additions...
1: Some analogue mixers do come with high-Z options on some of their inputs - Soundcraft Signature series being one that springs to mind.
2: You don't even need a mixer with subgroups - anything with at least one Auxiliary mix available (preferably switchable to post fader) will be able to achieve the same effective end result.
1: Some analogue mixers do come with high-Z options on some of their inputs - Soundcraft Signature series being one that springs to mind.
2: You don't even need a mixer with subgroups - anything with at least one Auxiliary mix available (preferably switchable to post fader) will be able to achieve the same effective end result.
Both is ofcourse true. The Soundcraft Signature got subgroups (except the 10) and is the full digital package, which comes at a price, weight and size. It's probably not necessary to crack a nut with a sledgehammer - in the end it's coming down to what he really needs. Maybe a cheap/used mini mixer and the tiny circuit I've posted will do at a fraction of the cost, depending on what he's actually doing.
If you want good EQ, then probably a small ready-made mixer is going to be the simplest sollution.
You can simply make pre-amps for the piezo and magnetic pickups (e.g. Guitar Contact Microphone Preamp: 7 Steps ) and install them inside the mixer.
If you can't find a battery powered mixer (some Audio Developments mixers take batteries) then find one with external power supply of say 12V and make a battery pack.
You can simply make pre-amps for the piezo and magnetic pickups (e.g. Guitar Contact Microphone Preamp: 7 Steps ) and install them inside the mixer.
If you can't find a battery powered mixer (some Audio Developments mixers take batteries) then find one with external power supply of say 12V and make a battery pack.
I also thought about that. It would be quite convenient because it would lower the requirements for the mixer quite much and it would favour the 'one-in-all' solution. I don't like the idea of the battery in the instrument that much, it has to be accessible. A circuit which can be powered by the phantom power would not need that but it's more complex because it's not stable and it has to work on a relatively wide range of voltages, both can affect the sound. Still a very tempting, elegant solution and there are surely solutions ready-made and proven to be relyable on the market. DIY would be much cheaper though.
My idea with the velcro mount on the mixer would ofcourse also work on the guitar (or whatever instrument it is). It could also be put on the strap or on a cable clip which keeps the 3 pickup cables together.
Looking at the specs for the Soundcraft Signature, the Hi-Z Input has 968kΩ:
But the Fishman BP-100 piezo recommends a 10 MΩ:
So the idea to build a custom mixer is to get as best as possible the minimum components to keep it the best fit and also very portable
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Well, it's not pretty but it works. How much do you want to spend on the solution?
A Behringer X Air XR18 got an input impedance of 1M/2M (unbalanced/balanced) and costs 400 bucks, it's set up by a laptop, tablet or phone. The Soundcraft mixer is 500. I haven't found mixers with a higher input impedance than 2M yet.
A really cheap solution would be to just mount your mixer, preamp, cables etc onto a board. Still not nice to look at but less than 5 bucks. You could also put it on a board and then in a case like like this or this one. Clean, easy and fast to set up and put away again.
Such a pedal case would probably be even better suited:
Thon Effect Case for Line 6 Helix – Musikhaus Thomann
Thon Effect Case for Line 6 Helix – Musikhaus Thomann
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