Preamp/Filter input voltage range question

[tx196059]

Hello all, I am wondering if any of you have been thinking about a way to use a 5 pin connector on a non-Series I or II Alembic. From what I have read in past discussions, pins 4 and 5 are 20v +/-


http://club.alembic.com/index.php?topic=2326.msg28515#msg28515


I saw a Distillate for sale on Reverb that converted the electronics to stereo, and added a 5 pin cable, with power supply.


https://reverb.com/item/4827405-alembic-custom-stero-studio-distillate-1982-distillate-colors


I am thinking that is a great idea! No Batteries! Problem is, these single card filters run on a 9v battery. So my question is, what is the input voltage range of these filters? Will they burn up at 20v using my DS-5, or do I need to put an on-board buck converter in-line after the 20v input on the bass, and step it down to 9v, running it parallel to the battery 9v input? And if that is the only option, will it need RF shielding? Thanks!


Joe

[edwardofhuncote]

Joe, I saw that Distillate too.

Turns out, one of my 'buddies' on TalkBass forum has actually done something like what you are describing. He replaced the electronics in his Spoiler/Exploiter with a Volume/Pan/Filter/Q harness, and made a 9v power supply to run his bass on without need for batteries. Don't remember if he used a 5-pin or XLR cable. Anyway, it can be done... whether advisable or not is another subject. Sounds like a cool idea to me.

The really interesting thing was what he did with the old Spoiler guts... he built them into an outboard preamp box for use with other basses. Calls it his Ron-o-Tone.  (Rickenbackers are more his thang...)

[tx196059]

Thanks Greg. Cool idea about using Alembic preamps externally. Like me using a Spoiler through an SF-2, for a poor man's Series II. The XLR cable would work fine for mono. Stereo conversions I am doing need a 5 pin though. I put a toy car 9v recharable battery in a Modulus Monocoque Flight 4, because that bass requires the pickups to be removed to change the battery. I drilled a small hole in the carbon fiber, and installed a charge port. Now I can plug in the bass like a cell phone to charge it. Big battery to, does not need charging for a long time.


https://www.amazon.com/dp/B001BBMZFU/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=1BZ03P2V13890&coliid=I2STAZI4N5QQQC


For the sake of keeping me from blowing up 9v preamps, just wondering what the voltage range is for them, and if the can handle the 20v. I could install a dc/dc converter on the bass, but I am worried about RF issues. I would like to make all my active preamp guitars rechargeable or plug in, so I do not have to go to Costco for 9v batteries anymore.


Cheers!


Joe
 

[jon_jackson]

Joe, I don't know how the D-I-Y version would go together, but using a 5-pin cable from a DS-5 for Alembic non-series basses is possible, at least for a new build. When I had my replacement Dragon Wing made, I asked that it be able to be powered and connected via a DS-5 so I could interchange it with my Series basses. It has Anniversary electronics and can use either the 5-pin / DS-5 or batteries / 1/4" jack to connect.
Jon

[tx196059]

Hey Jon, thanks for the input. I am also trying to standardize my guitars to the 5pin. I can add an inline Buck Converter to step down the 20v at the box, or do it on each bass, so I do not accidentally plug 20v into the 9v system by forgetting to flip the switch. They are cheap enough to buy a bunch of them. Just finding the real estate in the control cavity will be an issue.


https://www.amazon.com/eBoot-LM2596-Converter-3-0-40V-1-5-35V/dp/B01GJ0SC2C/ref=pd_bxgy_23_img_2?_encoding=UTF8&pd_rd_i=B01GJ0SC2C&pd_rd_r=NCBTW7QC6Z99TTSRX5ZR&pd_rd_w=81MEe&pd_rd_wg=nSYdl&psc=1&refRID=NCBTW7QC6Z99TTSRX5ZR


I have an old Alembic 9v filter that needs replacing, so it will be my sacrificial test bed, as I teak up the voltage to see what happens. I will also put a Buck Converter into a bass to see if the RF is going to be a problem. If so, I will see if I can make a small RF Faraday Cage for it.  Cheers!


Joe

[rjw]

Hi Joe,

We have installed custom 5-pin jacks on models that are powered by 9-volt batteries and we use a 10 Volt Zener diode as a shunt regulator with a series dropping resistor selected to provide 5-10 mA through the regulator with the electronics energized.   Also connect a large Aluminum Electrolytic capacitor, such as 100 micro-Farads at 25 Volts across the regulator to reduce noise.    The filter can handle up to 12 Volts, due to the ratings of the bypass capacitors for the voltage divider that normally provides the bias voltage for the Op-Amp.   Those capacitors are rated at 6 Volts each so in series that sets the maximum voltage at 12 Volts. 

Most people request that the 1/4 inch output jack also remain along with the battery so the instrument can be run either from battery power or the external 5-pin cord.   So we also put a Schottky diode in series with the battery supply from the 1/4 inch jack.

This would apply to almost all battery-powered Alembic electronics, with one exception.  And that is the Distillate model referenced above.  Note the LED next to the 1/4 inch on the Distillate pictured.   This version of the Distillate electronics does not have the negative lead of the battery grounded.   Instead the center point of the bias voltage divider is grounded, and the battery provides -4.5 Volts and +4.5 Volts referenced to ground and not 9 Volts (Similar to the voltage supply for Series Instruments which have the dual-polarity power supply).   While I haven't had a request for converting a Distillate to 5-pin external power, I'd use two 5.1 Volt Zener diodes along with two series dropping resistors to make the DS5 power supply output compatible with the Distillate circuit.

Using the DC/DC converter (Buck Regulator) you reference should be ok as well.

-ron

[tx196059]

Hi Ron, a million thanks for the missing pieces of the puzzle. I was not looking for the shunt/resistor route without knowing the voltage and load variance. Your way would be a lot easier to find room for the components. I am going to breadboard both options to see which provides the least RF. I may put in a DPST switch to separate the 5 pin, and a rechargeable 9 volt battery system. And thanks for the heads up on the Distillate system, since I will be doing a conversion on an LED version I recently acquired. I hope you and your family have a great Easter.


Cheers!


Joe