How much current does your bass preamp use

[Eight_Stringer]

Brice Z6 fretless spalted maple 3,8mA
Brice Z6 fretless Trans Blue 0,31mA cool running bass. Obviously a different preamp or problem on the spalted maple.

Tune Maniac 4 and 5 string ( Korean ) 3 by LF442 1mA

Yamaha RBX800A 4,5mA at 16V(*)

Ibanez SR706 and SR705 ( Korean ) 1mA

Custom 7 string bass ( Korean ) 7,2mA at 18V ( now 16V )

( *) Fabricated a battery eliminator for all the active basses, ( additional 7 basses over the above ) supplies 16V DC. Not all increased current draw at the elevated supply rail. Caveat, watch out for tantalum capacitors in preamps. They do not take kindly to reverse polarity, including a series diode in the supply line of some preamps. You will actually have a supply rail of minus 0,6V ( -0,6VDC ) on the down stream load of the reverse biased diode, enough to nuke a vulnerable Tantalum capacitor ( internal short circuit is first fail condition and then overheat to open circuit if enough power supply grunt ). Also over volting a tantalum is another no no. 18V is not a usual rating for tants, 16V usual maybe 25 and then 35V working volts, plus or minus feed impedance to the capy, for actual supply on capy terminals.

HTH.

[mizu]

Originally Posted by mizu

I've just measured the current draw on my Cirrus and Millennium Plus.
Both USA made, both have same preamps with sweepable mid.

Cirrus: 9.8 mA
Millennium Plus: 1.2 mA

Looks like those VFL pickups are real power hogs

Yup, it's the pickups. Got tired of changing batteries montly, so had decided to have a closer look at the issue. And it turned out that the newer, circa 2008 Cirrus VFL pickups draw 4,7 mA each.
Interestingly enough, I have an older pickup from a production model Cirrus made in late 90s and it draws only 0,3 mA. Go figure

[InternetAlias]

Hey guys, anybody have an idea how much current one Tillman draws? Thanks

[BassLife77]

Originally Posted by InternetAlias

Hey guys, anybody have an idea how much current one Tillman draws? Thanks

After 2 years the battery reads at 8.7V. Mine has the J201 and I used a variable resistor for the drain to bias it to 4.5V. I play the bass almost daily. I don't know the science of this but I think its a combination of using a switching jack, biasing it to half the supply voltage, and not adding the boosting cap option is why the current draw is so low. Plus the Tillman has a really hot output even without the boost option and increasing the supply voltage makes it hotter

[InternetAlias]

How does one change the drain? I probably just need to put a resistor somewhere, but where, is it the one between the battery and transistor? I didn't actually expect someone to reply so soon, it's good to know it can last a while, thanks

[BassLife77]

Originally Posted by InternetAlias

How does one change the drain? I probably just need to put a resistor somewhere, but where, is it the one between the battery and transistor? I didn't actually expect someone to reply so soon, it's good to know it can last a while, thanks

The drain is R2 (2.2K) on the Tillman schematic. You can put a variable resistor there to bias the transistor to half the battery voltage. I found it to sound better that way. or you can just put in a 2.2K resistor there.