crt said:
and for R1 = 220K still in use ?
270K-330K ? where i put this resistor ? can you draw me a simple schematic please.
Today i have replace the old 25K stepped attennuator with 22K value.
recalculate all the resistor again, that's pain but FUN!
I am talking about R1 always. I just say it may be 10-15X your pot value, and always there, especially with a switch pot. The moment there is no gate reference to ground, 4VDC can appear at the output.
15.000 uF will be a little overkill but I could be wrong in the eyes of many. Better use two 2200 or 4700 uF caps with a resistor or coil in between. Everything before the regs of course. After the regs 100 uF and a 0,1 uF MKT/MKP. Some regs do oscillate with 1000 uF at the output.
I would advise to use separate supplies for the 2 channels. It could be wise to provide pads for shorting the input and output caps. Just in case the source has a DC component you can remove the jumper and you will have a coupling cap. Just an idea that adds functionality that could be useful.
Maybe I am old fashioned but if you provide board space for a RK27 potentiometer you could add an input RC filter before the potentiometer to avoid RF straying in. A -3db point of 40 to 50 kHz would be enough. You never know with all the RF garbage in the air. The B1 has a bandwidth of 10 MHz if I am not mistaking.
The icing on the cake would be 4 or 5 relay switched inputs. That would be a PCB for "B1 Deluxe" everyone will want
me too...
I would advise to use separate supplies for the 2 channels. It could be wise to provide pads for shorting the input and output caps. Just in case the source has a DC component you can remove the jumper and you will have a coupling cap. Just an idea that adds functionality that could be useful.
Maybe I am old fashioned but if you provide board space for a RK27 potentiometer you could add an input RC filter before the potentiometer to avoid RF straying in. A -3db point of 40 to 50 kHz would be enough. You never know with all the RF garbage in the air. The B1 has a bandwidth of 10 MHz if I am not mistaking.
The icing on the cake would be 4 or 5 relay switched inputs. That would be a PCB for "B1 Deluxe" everyone will want
me too...
Salas said:
jean-paul said:15.000 uF will be a little overkill but I could be wrong in the eyes of many. Better use two 2200 or 4700 uF caps with a resistor or coil in between. Everything before the regs of course. After the regs 100 uF and a 0,1 uF MKT/MKP. Some regs do oscillate with 1000 uF at the output.
I would advise to use separate supplies for the 2 channels. It could be wise to provide pads for shorting the input and output caps. Just in case the source has a DC component you can remove the jumper and you will have a coupling cap. Just an idea that adds functionality that could be useful.
Maybe I am old fashioned but if you provide board space for a RK27 potentiometer you could add an input RC filter before the potentiometer to avoid RF straying in. A -3db point of 40 to 50 kHz would be enough. You never know with all the RF garbage in the air. The B1 has a bandwidth of 10 MHz if I am not mistaking.
The icing on the cake would be 4 or 5 relay switched inputs. That would be a PCB for "B1 Deluxe" everyone will want
me too...
Thank's for advice Salas and Jean-Paul.
now, the layout about 60% to finished
and maybe on saturday i can bought my layout to the PCB maker and take 4-5 days to finished.
I can not wait any longer to build this one too.
La Ode
Using B1 with an amp requiring balanced inputs
I am nearly done building my B1 preamp, thanks to Colin at DIY Pass and those who kindly responded. That said, I'm not quite sure where I choose to use the preamp. In one set up I can utilize the unbalanced RCA outputs, but in another the amplifier requires balanced XLR inputs.
I have seen some discussion of this topic before, albeit I am unsure on how to proceed. Any suggestions would be much appreciated.
Timothy
I am nearly done building my B1 preamp, thanks to Colin at DIY Pass and those who kindly responded. That said, I'm not quite sure where I choose to use the preamp. In one set up I can utilize the unbalanced RCA outputs, but in another the amplifier requires balanced XLR inputs.
I have seen some discussion of this topic before, albeit I am unsure on how to proceed. Any suggestions would be much appreciated.
Timothy
Re: Using B1 with an amp requiring balanced inputs
To use the B1 in a balanced application, you'd need four "channels" of B1 - two each for the left and right balanced channels. To do this you'd probably want to use matched quads of jfets. If that's not what you've built, you may as well use it in your unbalanced setup.
-j
timothyshields said:
To use the B1 in a balanced application, you'd need four "channels" of B1 - two each for the left and right balanced channels. To do this you'd probably want to use matched quads of jfets. If that's not what you've built, you may as well use it in your unbalanced setup.
-j
Hi Nelson
I just wanted to say I finished my B1 yesterday. I took it into work today and got a friend (electrical engineer) to do some measurements.
I didn't say too much about the design.
The first thing he said was, where are all the active devices?
I don't know what his initial impressions were before testing, but after testing he said, it is better than good, it is amazingly good.
So I felt pretty good with myself since this is my first complete diy project.
I hope that you also take this as a compliment Nelson.
Anyway I can't actually listen to it yet because I am still finishing my amps.
Just out of curiosity I was wondering if anyone here had built both the B1 and BOZ and could elaborate on which one they preferred sound wise, or describe any differences if any?
I just wanted to say I finished my B1 yesterday. I took it into work today and got a friend (electrical engineer) to do some measurements.
I didn't say too much about the design.
The first thing he said was, where are all the active devices?
I don't know what his initial impressions were before testing, but after testing he said, it is better than good, it is amazingly good.
So I felt pretty good with myself since this is my first complete diy project.
I hope that you also take this as a compliment Nelson.
Anyway I can't actually listen to it yet because I am still finishing my amps.
Just out of curiosity I was wondering if anyone here had built both the B1 and BOZ and could elaborate on which one they preferred sound wise, or describe any differences if any?
Yeah . . .
It seems like CW=Clockwise W=Wiper CCW=Counterclockwise . . .
If we turn the volume to the CW, the sound should go lounder so that CW should go to the input side. In opposite way, it we turn the volume to the CCW, the sound goes lower so that CCW should go to the ground. Then, the wiper should go to the output.
Just my positive guess . . . based on Tea-bag's reply . . .
><
It seems like CW=Clockwise W=Wiper CCW=Counterclockwise . . .
If we turn the volume to the CW, the sound should go lounder so that CW should go to the input side. In opposite way, it we turn the volume to the CCW, the sound goes lower so that CCW should go to the ground. Then, the wiper should go to the output.
Just my positive guess . . . based on Tea-bag's reply . . .
>
<
Babowana said:Yeah . . .
It seems like CW=Clockwise W=Wiper CCW=Counterclockwise . . .
If we turn the volume to the CW, the sound should go lounder so that CW should go to the input side. In opposite way, it we turn the volume to the CCW, the sound goes lower so that CCW should go to the ground. Then, the wiper should go to the output.
Just my positive guess . . . based on Tea-bag's reply . . .
>
I hooked it up that way, and it seems to act like a normal volume pot, and doesn't work counter-clock wise. of course I only did that cause I referenced your picture earlier
I still need to put the board into box with some connectors and really listen to it.
Re: Re: Re: cap tolerance
The purpose of the input cap is block and DC on the signal from your source. For this purpose, I think any old cap would do.
However, the input impedance and the input cap together form a high-pass filter. At the "corner frequency", the signal is diminished by 3dB (just barely audible). Above this frequency, the attenuation diminishes asymptotically to 0, and below it, the attenuation increases. In the case of a 25% tolerance part and a 25K pot, the corner frequency would be anywhere from 8.5Hz (-25%) to 5.1Hz (+25%) (ie. you shouldn't be able to hear the difference).
The higher the corner frequency too, the more (possibly) audible phase shift you'll see in the bass region, below say, 80Hz (guesstimate). Even with a -25% 1uF cap though, it shouldn't trouble you. In fact, thinking about it will trouble you a lot more than listening to it.
-j
jacq. said:
The purpose of the input cap is block and DC on the signal from your source. For this purpose, I think any old cap would do.
However, the input impedance and the input cap together form a high-pass filter. At the "corner frequency", the signal is diminished by 3dB (just barely audible). Above this frequency, the attenuation diminishes asymptotically to 0, and below it, the attenuation increases. In the case of a 25% tolerance part and a 25K pot, the corner frequency would be anywhere from 8.5Hz (-25%) to 5.1Hz (+25%) (ie. you shouldn't be able to hear the difference).
The higher the corner frequency too, the more (possibly) audible phase shift you'll see in the bass region, below say, 80Hz (guesstimate). Even with a -25% 1uF cap though, it shouldn't trouble you. In fact, thinking about it will trouble you a lot more than listening to it.
-j