Hello!
I am in need of some additional gain (at minimum +12dB) but both the voltage is limited to 3 volts and it needs to be extremely basic (preferebly single FET) as to fit onto a 5x2cm veroboard.
The only control I need is volume.
The purpose is to boost the signal level of a passive electric bass.
Do you have any suggestions?
I am in need of some additional gain (at minimum +12dB) but both the voltage is limited to 3 volts and it needs to be extremely basic (preferebly single FET) as to fit onto a 5x2cm veroboard.
The only control I need is volume.
The purpose is to boost the signal level of a passive electric bass.
Do you have any suggestions?
A rail to rail op amp, like the OPA347PA and others, is able to work on 3V single supply. It is available in the SC70-5 package, about 2mm x 2mm.
Are you sure that 1.5V peak is enough headroom?
https://www.ti.com/lit/ds/symlink/opa347.pdf
Are you sure that 1.5V peak is enough headroom?
https://www.ti.com/lit/ds/symlink/opa347.pdf
a few more bipolar opamps ; OPA1671, ADA4897,AD8655, ADA4084,....
OPA1671 must have some sort of FET input stage, as it has very little equivalent input noise current. ADA4897 is a typical bipolar low noise voltage, high noise current type.
Normally electric guitars are rather high impedance, so you wouldn't want a high noise current amplifier. I'm not sure about electric bass guitars, though; at low frequencies, the impedance of an inductive guitar is still low, but that doesn't help much when the guitar amplifier amplifies everything up to the highest audio frequencies.
Normally electric guitars are rather high impedance, so you wouldn't want a high noise current amplifier. I'm not sure about electric bass guitars, though; at low frequencies, the impedance of an inductive guitar is still low, but that doesn't help much when the guitar amplifier amplifies everything up to the highest audio frequencies.
An electric guitar can clip a 3V circuit with no gain at all, so you need some way to throttle the input or gain, unless you are making a fuzz pedal. Also, the input impedance of a guitar amp has to be at least 500K Ohms. Perhaps you just need a buffer. And 3VPP in not likely enough to drive a power amp. Working with a 9V battery is a challenge. This is one reason musicians dislike "solid-state" amps, ie the limited supply voltage of the input stage clips easily.
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I have seen active bass guitars that used 2 x 9V blocks.
Anyway, output level widely varies with your picking technique.
My acoustic guitar magnetic pu is supplied by 3V, but the amp is a simple buffer.
Btw I am convinced that some clipping of initial percussion peaks does not really matter.
Anyway, output level widely varies with your picking technique.
My acoustic guitar magnetic pu is supplied by 3V, but the amp is a simple buffer.
Btw I am convinced that some clipping of initial percussion peaks does not really matter.
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My electric bass is pretty quiet. I need the extra gain to properly utilize the Rockboard HA1 (portable headphone amp for cheap live monitoring). I opened it up and there is a good deal of free space in the housing where I plan on putting the additional gain stage. Would be a very clean solution but it means that I only have the onboard dual AAA batteries as power source available.
Should be enough, though.
My other (active) bass has a very hot output and with the Rockboard at 3/4 volume it alreadys hurts my ears (without distorting).
Should be enough, though.
My other (active) bass has a very hot output and with the Rockboard at 3/4 volume it alreadys hurts my ears (without distorting).
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Your other active Bass does NOT have a 3V supply preamp.
Think about it.
Your solution is to add a 9V powered preamp to your current Bass.
Or to find and solve the problem as to why your Bass is so weak.
Think about it.
Your solution is to add a 9V powered preamp to your current Bass.
Or to find and solve the problem as to why your Bass is so weak.
But it still has to go through the 3V headphone amp. Wouldn't that void any actual advantage in terms of clean gain that a 9V preamp gives me since the total headroom is ultimately limited by that stage?
Could you examine it in more details: it might be possible to increase the gain just by changing a resistor.
Otherwise, what's the input impedance?
If I have that information, I can design a suitable common-emitter stage
You said yourself that the Active Bass drives it better, way better.
We are suggesting you turn your Passive Bass into an active one too, simply by adding what you are asking for; in this case a simple 9V powered 12dB gain preamp.
High input impedance to match current circuit, low output impedance to drive your in ear monitors.
Maybe a 3V powered buffer (no voltage gain) is enough IF you actually have an impedance problem, why not? .. but we already have a tested solution: a Bass preamp.
I bet your active Bass uses a 9V battery (or two), not two AA batteries.
There is no schematic available but I could post a picture of the PCB if that would help.
I'd much prefer modding the headphone amp over carving out additional routing in my bass for a battery or having to carry around another external preamp. This setup with the headphone is already a bit messy. Any additional stuff and I would have doubts using it live.
Plus the gain of the headphone amp is also too low for my condenser mic.
No need to carve your Bass, you can use 2 or 3 CR2016 or CR2032 button cells which fit anywhere inside the pots cavity. You can use a low power OpAmp
The PCB can be literally thumbnail size and a switching jack means power is ON only while playing. Those batteries will last over a year.
Just thinking aloud, the choice is yours.
You would need to build a 3V preamp anyway, probably needing to design a mini PCB and ordering on China.
Also post Bass pictures; showing pot cavity inside would be the cherry on the cake.
The PCB can be literally thumbnail size and a switching jack means power is ON only while playing. Those batteries will last over a year.
Just thinking aloud, the choice is yours.
You would need to build a 3V preamp anyway, probably needing to design a mini PCB and ordering on China.
Also post Bass pictures; showing pot cavity inside would be the cherry on the cake.
Well nothing lost I suppose but it might not be possible to determine the configuration from just a picture.