Two Boards from One Wall Wart
I am building a four channel B1 buffer using two stereo boards. I am using a single wall wart which has 18 volt and 1.1 amp (HP power adapter for a printer).
Each board will be attached to the same wall wart. Each board will be fully populated. Meaning each board will have its own set of power supply caps and resistors (C1, C2, C3, R1, R2, R3 etc). Ultimately all the grounds will be tied together (IOW, the grounds on each board are linked)
As recommended I will be using 15,000 uF caps for C1 & C2. My naive thought is that since the grounds are all tied together, am I actually gaining more capacitance in the power supply filtering? Would the value of R1 need to be changed (currently it is 1 ohm 3 watt).
Is there something I am forgetting by hooking two boards up to a single power adapter?
What is obvious to some is not obvious to me.
Thanks
I am building a four channel B1 buffer using two stereo boards. I am using a single wall wart which has 18 volt and 1.1 amp (HP power adapter for a printer).
Each board will be attached to the same wall wart. Each board will be fully populated. Meaning each board will have its own set of power supply caps and resistors (C1, C2, C3, R1, R2, R3 etc). Ultimately all the grounds will be tied together (IOW, the grounds on each board are linked)
As recommended I will be using 15,000 uF caps for C1 & C2. My naive thought is that since the grounds are all tied together, am I actually gaining more capacitance in the power supply filtering? Would the value of R1 need to be changed (currently it is 1 ohm 3 watt).
Is there something I am forgetting by hooking two boards up to a single power adapter?
What is obvious to some is not obvious to me.
Thanks
Re: Two Boards from One Wall Wart
Perhaps the lack of input is due to my misarticulation of the question. Let me try another approach. I am using two stereo boards (4 channels).
My first thought was to parallel each board off a single wall wart and each board would be fully populated (both buffer sections and the power supply filtering).
My second thought was that each power supply section currently drives two buffers (left and right channels). So why not use the power supply section on a single board to drive the 2 channels on the first board AND the two additional channels on the second board. IOW, don't populate the power supply section on the second board. Rather, take a wire from the power supply side of R203 (or R103) and connect it to the equivalent Resistors (R103 and R203) on the second board.
I assume there would not be a problem since each channel is drawing fairly little current.
Thoughts or concerns? Am I missing something. I checked the previous threads and I don't think anyone has done something comparable.
Thanks
WithTarragon said:
Perhaps the lack of input is due to my misarticulation of the question. Let me try another approach. I am using two stereo boards (4 channels).
My first thought was to parallel each board off a single wall wart and each board would be fully populated (both buffer sections and the power supply filtering).
My second thought was that each power supply section currently drives two buffers (left and right channels). So why not use the power supply section on a single board to drive the 2 channels on the first board AND the two additional channels on the second board. IOW, don't populate the power supply section on the second board. Rather, take a wire from the power supply side of R203 (or R103) and connect it to the equivalent Resistors (R103 and R203) on the second board.
I assume there would not be a problem since each channel is drawing fairly little current.
Thoughts or concerns? Am I missing something. I checked the previous threads and I don't think anyone has done something comparable.
Thanks
Check if your amp has an input cap. If it has one I would not worry. Those are very good values !
If you have a DC coupled amp ( = without input cap ) the DC could be a minor problem as the amp would amplify the DC component. That is bad for woofers. That is why I told you to include a possibility for an output cap on the PCB.
Most amps have the input cap and most preamps have output caps. So in the real world in much cases you will find that 2 caps are in series when you couple such devices. I have never understood why the industry did not find a standard way of doing things like "always input caps and no output caps" or vice versa. Just one cap really is enough !
If you have a DC coupled amp ( = without input cap ) the DC could be a minor problem as the amp would amplify the DC component. That is bad for woofers. That is why I told you to include a possibility for an output cap on the PCB.
Most amps have the input cap and most preamps have output caps. So in the real world in much cases you will find that 2 caps are in series when you couple such devices. I have never understood why the industry did not find a standard way of doing things like "always input caps and no output caps" or vice versa. Just one cap really is enough !
crt said:
Yes it will be fine to offset the supplies enough. True symmetry is manifesting in DC offset. You just offset the Jfets differences by doing that. Anyway your offset is negligible even with no trimming. Waiting to see your pictures, and know if you can hear differences over the capacitor coupled B1.
Originally posted by Salas
Yes you can use 25k, only make the wiper to ground resistor 270k-330k. Don't omit that resistor! Strong DC will show up at output when switching the step attenuator if without that shunt resistor.
6VRMS input it can handle if with +/- 10VDC PSUs.
Good luck, I hope you will like it. Report your news.
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Can I run the B1 without this resistor???
Wiper to ground mean what?
Yes you can use 25k, only make the wiper to ground resistor 270k-330k. Don't omit that resistor! Strong DC will show up at output when switching the step attenuator if without that shunt resistor.
6VRMS input it can handle if with +/- 10VDC PSUs.
Good luck, I hope you will like it. Report your news.
-------------------------------------
Can I run the B1 without this resistor???
Wiper to ground mean what?
Hi
I am looking to build a B1 and i found i have some parts at home i am trying to use.
I found a pair of good 4,7uF MKP and a pair of even better 2,2uF MKP that i am looking to use.
Would it be ok to use the 4,7uF instead of the 10uF for C101 and C201.
And the 2,2uF for C100 & C200?
How much would this effect that sound and performance of that circuit.
I am looking to build a B1 and i found i have some parts at home i am trying to use.
I found a pair of good 4,7uF MKP and a pair of even better 2,2uF MKP that i am looking to use.
Would it be ok to use the 4,7uF instead of the 10uF for C101 and C201.
And the 2,2uF for C100 & C200?
How much would this effect that sound and performance of that circuit.
Thank you for the answer.
I also plan to lover the input R102 and R202 as i have read some hear that they could improve the sound and make it more dynamic.
I will keep the input caps at 1uF as i found some of them and try with lover both R102, R202, R104 & R204 to 221 Ohm to start with. then ma by lower R104 and R204 even more.
Then i will order some 10uF to but for C out.
Or could i use the 4,7uF for that and use 221 ohm for out put R .
Or could anyone help me with the formula to calculate the frequency curve.
I have some 4700uF caps to use for C1 and C2.
Will i gain anything to put 2 in parallel to get 9400uF.?
I also plan to lover the input R102 and R202 as i have read some hear that they could improve the sound and make it more dynamic.
I will keep the input caps at 1uF as i found some of them and try with lover both R102, R202, R104 & R204 to 221 Ohm to start with. then ma by lower R104 and R204 even more.
Then i will order some 10uF to but for C out.
Or could i use the 4,7uF for that and use 221 ohm for out put R .
Or could anyone help me with the formula to calculate the frequency curve.
I have some 4700uF caps to use for C1 and C2.
Will i gain anything to put 2 in parallel to get 9400uF.?
thanh1973 said:
I fully support.
I have used the followings for my B1 (just as the original):
- Samsung computer dc adaptor
- Ctoole shunt regulator
- My Type A shunt regulator
- My Type E shunt regulator (current one I'm using happily)
But, I could not detect any particular sonic quality gain among these. Most probably, the shunts might work with their values on applications for other products than B1 tho . . .
It might be due to my ill ears . . .
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I think one of the reasons why it is not sensitive to power supply performance is that the design is unity gain so your not attenuating the input signal as much as you would be with a preamp with gain.
So the signal to noise ratio is quite good with the B1.
I am sure there are other reasons too.
So the signal to noise ratio is quite good with the B1.
I am sure there are other reasons too.