Single Wall Supply for Pass B1 and Bugle2

ervington

Member
2005-11-28 8:13 pm
DC
Hi all,

I have recently completed building up the Pass B1 and the Hagerman Bugle2, and I was hoping to run them off of a single wall supply since they can both be run at 24VDC and consume relatively little current. However, when attempting to run both powered by a single wall wart (the one that comes with the Bugle2), I find that while I get +10V at pin 8 of the opamps on the Bugle2, I get nothing on pin 4 where I should see -10V. Also, of course, I get no sound from the Bugle2 while I do get sound from my computer through the B1.

My long term plan was to build a separate power supply for these units regardless (looking at the AMB sigma11), but I want to understand where the problem is or if I perhaps have simply done something wrong.

1) Does it make sense that too low current is causing this problem? If so, would simply getting a wall power supply with a higher amp rating get me up and running cheaply/quickly?

2) Is it possible there is another issue/grounding issue I'm not understanding? I should note that I can run both units perfectly when I hook them up to their own wall warts, so this isn't a case of making the kit incorrectly.

My hope was to run the rail and ground to a switch (from glassware audio) so I could turn on just the B1 for regular use and leave the phono stage off unless I am playing vinyl. I understand this is probably unnecessary, but I thought it would be simple enough and also allow me to put both the Bugle2 and the B1 into the same enclosure with a single power cord. Which leads me to:

3) Is the Sigma11 a good option for running both of these units together?

I appreciate any help, and would appreciate keeping it related to the power supply issue since I'm sure I'm doing something really wrong in other areas like putting the Bugle2 in the same case as the B1 or something else. I'm going to work to improve things once I get it running! Happy to post photos later if that would help. For context, I'm building this as a preamp to drive a Dynaco St-70 that I brought back to life using Bob Latino's driver board because I was tired of using an old NAD integrated whose amp section had blown but could still work as a preamp.
 
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ervington

Member
2005-11-28 8:13 pm
DC
The Bugle2 takes 24 V single polarity, and I believe splits it to + and - 12V on the board. There is a schematic in the user manual, but the wall wart if came with was just a 24VDC unit. user manual here: http://www.hagtech.com/pdf/bugle2.pdf

The +10 and -10 are the voltages the manual says I should be reading at pins on the opamps.

The Pass B1 article says it will run from 18 to 24V, but I guess it is better not running at the max? I'm quite open to suggestions for the B1 power supply that aren't wildly expensive....

Anyway, maybe this is a fool's errand to begin with and I should just run them both separately.
 
It looks like the Bugle is converting the 0,24Vdc supply into a split supply with 0,12,24Vdc and using the 12Vdc as the virtual ground.
That is possibly where your two circuits are fighting against each other.
One is using a "ground" at 0Vdc and the other is using a "ground" at 12Vdc.

The B1 is definitely AC coupled at both input and output.
I have no idea what the Bugle does for the AC signal.
 

ervington

Member
2005-11-28 8:13 pm
DC
Thanks so much for this insight. I mean, I'm asking for solutions to a self-created problem here, so I need to just adjust. Especially since it sounds like the B1 does better with <22V anyway! It also gives me a good next project: building out power supplies for both units. So off to search the Pass forums for thoughts on that, I suppose, though I'd be happy to hear advice on popular options...