Dual regulated power supply with active mixer circuits

[garth4664]

Hello club members,


Hope it’s ok to post here. I’ve been working with local Australian luthier Tom Konig on a few projects and just wanted to share with the club one of his creations. He’s been building me a 15 string bass that requires a power supply. I asked him to use Alembic voltages and 5 pin setup so that I can use the new bass with my series 1, 2 and custom series instruments, thinking that I would be unlikely to play a full set on the 15. He came up with this work of art. It’s a twin stereo power supply, with dual regulated power outputs. Instead of the summing resistors there are twin active buffered mixer circuits for running mono mode. Not using summing resistors to run mono seems to really improve the mono outputs, and by running dual power supplies I can run 2 basses and up to four amps (or two mono channels) from one box. All the jacks and plugs are neuteric.Will post photos. It also looks very nice!

[garth4664]

Picture of dual power supply

[garth4664]

Picture dual power supply and Alembic blue one

[garth4664]

Yes, that’s two series basses being powered simultaneously

[garth4664]

Last one for good measure, the back

[garth4664]

Ok after a good afternoon using this new power supply and A/B testing my original ones I can’t understand why the standard power supply didn’t use an active mixing circuit instead of summing resistors. It’s obviously louder without them, but even adjusting the gains back to the same level this is definitely clearer too... do the in-2 modules have active mixing circuits for mono out. I feel like I’ve been missing out on this sound

[mario_farufyno]

Great job!

[goran]

That's very nice. And looks nice too.

[JimmyJ]

Garth,

Nice build!  Do you know if he hand-built the power supply sections or used pre-made modules?  Is it a quiet fan?  Very cool piece of custom kit.

As far as your summing question, it's up to the individual...  Passive summing is theoretically the cleanest way to mix two audio signals together.  There are currently many "passive" mixers sold (some surprisingly expensive) for the purpose of mixing down multi-track ProTools outputs.  Usually simple circuits of summing resistors followed by a buffer amp to regain any loss of level.  The thinking is that the least number of additional components in the signal chain will add the least amount of noise and coloration to the sound.

That said, on certain occasions in the past I have had the luxury of recording the bass in stereo and then slightly panned the two channels left and right.  This makes the bass appear to be mono but opens up some higher overtones that otherwise cancel.  It's a big sound which takes up a lot of space in the track so not always appropriate.  Of course, you're talking about your 15-string bass so you KNOW what a big sound is.   

Jimmy J 

[garth4664]

Hello Jimmy and friends,


Yes the whole unit is hand built including the custom case which he cnc’d in his workshop here in Canberra. There is no fan, that’s just a stylish vent. It’s got a regulated power supply so the voltage is nice and stable. And yes I think some of the high frequencies you are describing are audible now, the sound is definitely bigger! Have a look at Tom Konig’s website if you haven’t checked him out. Alembics and Konigs are it for me, no other basses will do (the blue 12 string is mine). Jimmy you would sound huge on this 15, it’s like a grand piano.


Thanks for the nice words, I’ll let him know you guys appreciate what Tom does.

[hammer]

Looks VERY nicely done!


A few questions: Does he make a rack mount version? Does the power regulation let avoid using a power regulator (could I drop the Furman and lose some weight) ? and what would be the cost for something like this?

[garth4664]

Hello Hammer,


Could possibly fit in a rack, you would have to check with Tom. He will make a few of these for me but I think he could be persuaded to do a little run.


I tthink you would be able to safely get rid of the power regulator for powering your bass, but you may want to keep one for your amps.


On cost, you would also have to check with Tom. It’s all hand build and hand designed but the quality is unbelievably good so it’s not cheap. I wouldn’t want to plug my instruments into a cheap power supply


Cheers,


Garth

[lbpesq]

I didn't notice a fuse, like on the Alembic Blue Box.  Is there an internal fuse, or some other protection circuit?

Bill, tgo

[garth4664]

Hello Bill the good one, the fuse on the dual power supply is built into the kettle cord plug, just on top of the cord in the photo above. Tom actually added the fuse to this particular Alembic supply too for me last year, it was an old one without a fuse before that.

[lbpesq]

Ah, technology!  Is it an actual replaceable fuse or a circuit breaker?  Very clean and professional looking unit.

Bill, the guitar one (who wouldn't presume to assume the mantle of "the good one")