Fishman Fluence Universal Battery Pack MOD

[h31k0]

Hello everybody!

@Mods: I'm new to the forum so please feel free to move this thread to the correct forum if needed. Thanks and apologies if this is not the correct forum for this thread. :-D
I have a pickup that needs 6V and draws very little current (it is being supplied by 2xCR2032 batteries).
Since they run out fairly quickly and I run through a lot of these batteries a year I was thinking of using the Fishman Fluence Universal Battery Pack MOD as a rechargeable solution.
The thing is that the Fishman battery pack supplies 9V instead of 6V. So how would I go about "reducing" the 9V to a 6V output?
I have contacted the pickup manufacturer as well as Fishman themselves.
The pickup manufacturer told me that I should be "very careful to never supply more than 6V to the pickup" and that I should "seek help and advice from a professional guitar electrician/engineer.
Fishman said they "do not recommend modding their battery pack".
What do you think? Is it possible? If so, how? :-)

Thanks for reading and taking your time to help me.

Cheers,
Heiko

[nosaj]

Please give up the other half of the equation. Ie info about the pickup, preamp, etc
Thanks,
nosaj

[The Dude]

I think easiest would be to make a series of diodes to drop the voltage. Probably 4-6 diodes depending on actual voltage drop of the diodes. Start with 4 and add more until you measure the 6 volts you want.

[nosaj]

I think easiest would be to make a series of diodes to drop the voltage. Probably 4-6 diodes depending on actual voltage drop of the diodes. Start with 4 and add more until your measure the 6 volts you want.

Got some pretty small real estate 1.5 x 1.74
https://www.fishman.com/portfolio/un...ry-pack/#specs
nosaj

[The Dude]

Well, you don't have to build it into the supply. The diodes can go in the guitar cavity after the supply.

[nosaj]

I personally feel this may be quicker and least cost.
https://www.amazon.com/CT-ENERGY-Rec.../dp/B08LN21K5Y
nosaj

[The Dude]

Yep. Recharchable 2032's and a charger would certainly work, albeit not as convenient as just plugging a USB cable into the back of the guitar.

[h31k0]

hey nosaj,

thanks for your reply!
so the pickup is a Vanden Mimesis Kudos Blend.
Unfortunately it is discontinued and the only official information out there is the user guide:
https://vanden.co.uk/wp-content/uplo...user-guide.pdf

The official website of the pickup is offline but the Wayback machine reveals it again:
https://web.archive.org/web/20181106...o.uk/kudos.htm

I have the "onboard mic"-edition and I am using it in active pickup mode.
I am using a TRS cable to have both the magnetic and the mic signals separated and then treat them differently in the mix.

SYSTEM SPEC. ACTIVE MAGNETIC PICKUP MODE
Pickup noise level -94dBu A -weighted

Mic Option 1
Mic noise level 33dBA
Mic Frequency response 100Hz...20Khz -2/+5dB

Mic Option 2 DPA4099G
Mic noise level 23dBA
Mic Frequency response 80Hz...15KHz +/-2dB

Max output level +3dBu
Output impedance <1Kohm
Recommended load impedance >10K ohms
Current consumption 1.8mA
Battery life approx. 80 hours

From my research that I have made so far I have found the following "options":
1. use resistors to drop the voltage
2. use zener diodes to drop the voltage (voltage divider?)
3. use a voltage converter.

Option 3 seems to be the only reliable one as long as the voltage converter has "proper protections" built-in and
is suitable for audio applications (as I fear there will be noise otherwise).

Let me know if I can help to provide more info. :-)

[nosaj]

I'd vote for using a 6v zener diode in smd package. It would be easiest to fit onto the board an insert into the voltage path.
nosaj

[nosaj]

This link provides a good pic of the PCB for others to peruse
https://www.ebay.com/itm/363510841456

[h31k0]

I personally feel this may be quicker and least cost.
https://www.amazon.com/CT-ENERGY-Rec.../dp/B08LN21K5Y
nosaj

thanks for this recommendation. that is something I hadn't thought of, haha!!
one thing I really like about using a rechargeable battery such as the Fishman universal battery pack is that it indicates how much battery is left.
because as you guys probably know, when a pickup's battery is starting to die the pickup's volume drops first then more, then distortion kicks in and so on.
I would love to have an indicator of how much battery I have left.
The other advantage of the Fishman battery pack would be that it claims to provide a stable 9V voltage throughout whereas
with batteries the voltage drops quite a bit already after some short time of usage.

[h31k0]

Thanks for your replies as well The Dude!
you guys are replying faster than I can read and answer :-D

[The Dude]

......From my research that I have made so far I have found the following "options":
1. use resistors to drop the voltage
2. use zener diodes to drop the voltage (voltage divider?)
3. use a voltage converter.......

Those options could be made to work, but here's why just using series diodes is easier.

1) Resistors- If you build a resistor voltage divider the guitar will draw extra current. If you use simply a series resistor, you have to calculate load, which is likely not consistent.
2) Zener- A zener diode to ground for regulation/drop will also draw extra current, plus you'd need a series resistor which also requires you to calculate load.
3) Voltage Converter- Most voltage converters or regulators I've seen require a higher than 9V input to have a regulated 6V output.

IMO, series diodes (not zeners) is the easiest solution. It's as simple as soldering diodes together until you get to 6V. You could then shrink wrap them together and use them in a wire run to the pickup(s).

[h31k0]

I'd vote for using a 6v zener diode in smd package. It would be easiest to fit onto the board an insert into the voltage path.
nosaj

alright! since you both suggest a zener diode would do the job I shall go for this but I have some questions
(sorry for asking but I fear my knowledge of circuits and soldering are too basic to figure it out myself):
1. would that zener diode be sufficient? if not would you be so kind to suggest a different one please?
https://eu.mouser.com/ProductDetail/...MoPDqcFQ%3D%3D

2. with "insert into the voltage path" you mean to solder it here?

[h31k0]

Those options could be made to work, but here's why just using series diodes is easier.

1) Resistors- If you build a resistor voltage divider the guitar will draw extra current. If you use simply a series resistor, you have to calculate load, which is likely not consistent.
2) Zener- A zener diode to ground for regulation/drop will also draw extra current, plus you'd need a series resistor which also requires you to calculate load.
3) Voltage Converter- Most voltage converters or regulators I've seen require a higher than 9V input to have a regulated 6V output.

IMO, series diodes (not zeners) is the easiest solution. It's as simple as soldering diodes together until you get to 6V. You could then shrink wrap them together and use them in a wire run to the pickup(s).

thanks for the detailed explanations The Dude! :-)
could you hint me to an applicable "series diode" (at mouser or similar) ?

as to point 3) how about this one here?
https://www.amazon.com/KNACRO-12V-6V...language=en_US

Input voltage: DC12V (Wide Voltage 8.5V-40V).

doesn't that mean it would run fine off of 9V ?