DIY cheap 9v preamp for dual source MIC

[Cuki79]

Nice work Ryan!

[rschultz]

Originally Posted by Cuki79

Nice work Ryan!

Thanks a lot!

[rschultz]

Here's the HPF rolloff plots:

Knob all the way to the left, 70 Hz:


Knob all the way to the right, 682 Hz:

[Cuki79]

Originally Posted by rschultz

Actually, it's Ryan

Sorry Ryan I corrected!

[Cuki79]

I have a question:
Since you use the HX stomp, why do you use an analog circuit for the HPF and not a digital one from the Line 6?

• More feedback resistance?
• More headroom?
• Save a block?

[rschultz]

Originally Posted by Cuki79

I have a question:
Since you use the HX stomp, why do you use an analog circuit for the HPF and not a digital one from the Line 6?

• More feedback resistance?
• More headroom?
• Save a block?

No you’re right. I have another PCB I’ve been working on that is smaller without the HPF that fits in a 2x2 box that I plan to use. I was just learning about various RC filters and decided to implement it in the preamp circuit. It could be useful for some people.

The helix can’t apply power, thus the reason for this T-power circuit. It can however apply gain… but it takes a good amount and I think it’s better to apply gain externally from helix. The HPF could be applied either place.

[rschultz]

Ooo, just got PCBs for preamp only.

[rschultz]

The preamp only version (no HPF) works great! I have to apply the HPF in my Helix, which is fine. But I like applying gain before the signal gets to the Helix.





It’s tight, definitely need to move a few things around on version 2.

[Cuki79]

Great job Ryan!

[Ten]

If you start selling these please let us know!

[rschultz]

Originally Posted by Ten

If you start selling these please let us know!

I'm happy to sell the DIY version, all the parts to build your own at my cost. I also could sell one of my prototypes, pretty plain looking but they work great.

PM me.

[Adrianw]

Cool. I've made a number of these. One in a 2x3 inch box with inputs and outputs for two electret condenser or MEMS mics. The box includes the 9v battery and even a voltage regulator. You can save a LOT of space by using 3.5mm jacks instead of 1/4 inch. Most of these mics use 3.5mm anyway and a 3.5mm x 1/4" cable or adapter works fine. I use these outside the guitar. Oddly enough I've found that running them into a K&K Pure battery powered preamp amps the signal very well while providing EQ. A dual preamp like the Schatten Mini works great too but without the EQ. I'm thinking of building something with the whole arrangement in one small box.... Power supply, mic ins and outs and the K&K preamp with eg. The preamp case is probably too tight but a 6x3 box might work.

[rschultz]

I have a prototype of each design that I’d send you for cheap. Lmk if you’re interested.

[Ten]

Originally Posted by rschultz

I have a prototype of each design that I’d send you for cheap. Lmk if you’re interested.

Your box is full!

[rschultz]

Crap, my subscription ran out. Sorry. Inbox FIXED!