I was planning to do this but I have a lot on my plate. I am willing to pay for 6 boards.
Could two B1s be use together to create a balanced preamp? If you wired each board's ground, left, and right to a 3-pin XLR jack's pins 1, 2, and 3, then used a balanced potentiometer, could this work?
Wow, thank you for the quick response. In that case, if I wanted to switch between an RCA or XLR input, could I have a switch that connects RCA to center L and G to outer shield, then shorts R to G? If only XLR input would be possible without some kind of transformer, then I'd just stick with XLR.
I would say yes.
Given the output impedance of the B1K and its ability to drive you should be able to drive the equivalent of 2 normal input impedance amps in parallel.
So unless your REL and power amp have silly input impedances (read of those much less than 10k) than IMHO should be OK.
Claude
Given the output impedance of the B1K and its ability to drive you should be able to drive the equivalent of 2 normal input impedance amps in parallel.
So unless your REL and power amp have silly input impedances (read of those much less than 10k) than IMHO should be OK.
Claude
successful BI-K build
Yesterday I completed the B1 Korg from the DIYaudio kit. Everything went fine on the build and the kit was perfect.
Upon power-up though I had a dead left channel on both inputs but board voltage was fine. To determine if the problem was in the wiring leading to the board (inputs, switch, pot) or a problem with the board, I unsoldered the wires connecting from the pot's L out that lead to the main board's L in. I then banana clipped the main board's L input wire to the pots R out and left channel output worked, confirming no problem in the main board.
...then after reheating all solder points leading from backplate inputs all the way to the vol pot...still didn't work. Focusing on L com input wire which is connected to both input A and B, I unsoldered L com in on bottom side of the pot to discover that insulation had melted around the stripped portion of wire and was not making electrical connection to the pot pcb...restripped it and soldered it back into the pot board and SUCCESS!
Fun build, it sounds great and very quite...a slight touch or "ringing after power up that seems to go away quickly....it sounds great and I love the gain! Thanks to NP for the design and other work, and Jim for the killer build guide.
Mario
Yesterday I completed the B1 Korg from the DIYaudio kit. Everything went fine on the build and the kit was perfect.
Upon power-up though I had a dead left channel on both inputs but board voltage was fine. To determine if the problem was in the wiring leading to the board (inputs, switch, pot) or a problem with the board, I unsoldered the wires connecting from the pot's L out that lead to the main board's L in. I then banana clipped the main board's L input wire to the pots R out and left channel output worked, confirming no problem in the main board.
...then after reheating all solder points leading from backplate inputs all the way to the vol pot...still didn't work. Focusing on L com input wire which is connected to both input A and B, I unsoldered L com in on bottom side of the pot to discover that insulation had melted around the stripped portion of wire and was not making electrical connection to the pot pcb...restripped it and soldered it back into the pot board and SUCCESS!
Fun build, it sounds great and very quite...a slight touch or "ringing after power up that seems to go away quickly....it sounds great and I love the gain! Thanks to NP for the design and other work, and Jim for the killer build guide.
Mario
Attachments
Put me down for four as well. Thanks for taking this on in the spirit that Mark has suggested.
...and thank you Mark for making these available to the community!
Cheers,
Scott
...and thank you Mark for making these available to the community!
Cheers,
Scott
Hi, I used a 50k pot. The gain is so much, on cd and tv I can not turn up to step 3 ( 21 step pot ) before I get my man next on my door.
On dac played from PC no problem as I just adjust the volum.
Today I tryed a 10K pot, its the same. step 3 is to load. I know someone here say that change to lower resistance pot will not help but I hade to try ( :
What to do? Want moore adjustments on the preamp.
Frank
On dac played from PC no problem as I just adjust the volum.
Today I tryed a 10K pot, its the same. step 3 is to load. I know someone here say that change to lower resistance pot will not help but I hade to try ( :
What to do? Want moore adjustments on the preamp.
Frank
value of the Volume pot, except in case of using ridiculously low value, is not having anything with gain of stage
except in case where pot is used in role of gain setting, but that's other story, and not the case here
except in case where pot is used in role of gain setting, but that's other story, and not the case here
You can put a resistor in series between the input and the pot. One resistor per channel.
Yep, I was that one telling you... again sorry for you :-(
If you can't change the gain of other devices, you may want to put an attenuator / voltage divider in front of your pot.
That is not too complicated but not completely straightforward as you need to look at impedances (in and out) and also capacitive loads.
You could start trying experimenting easily with a few resistors to see if you like it until you find "your values". To make it simple, I would build it just before the volume pot with as short as possible wires, well noting a few inches aren't really a problem. But say inside the same casing or worst case in form of a plug between your RCA input cables and the B1 Korg's RCA inputs.
You will find lots of info on internet (voltage divider, attenuator are the key words), it is just 2 resistors per channel, one in the signal path, the other to ground, like a fixed volume pot.
As the 10k pot seemed to work fine otherwise, you could arrange your voltage divider to be a 10k set up and then go into your 50k pot (should given short distances though also work into your 10k pot).
The values of the resistors will determine impedance and attenuation. How much you want to "spread" your volume control to be comfortable depends entirely on you, but I would say iven your comments that you may want at least a 20dB attenuation network.
The sum of the 2 resistors will give you the impedance your source sees... and up to 1/4 of that value (so in most cases much less) the impedance your pot would see.
Good luck
Claude
EDIT: putting only a single resistor in the signal path could indeed work but given what your posted it would probably need to be a hell lot of Ohms and bring possibly other negative hence suggesting on my side a voltage divider as you really want to attenuate quite a lot. But just IMHO and I could be wrong...
If you can't change the gain of other devices, you may want to put an attenuator / voltage divider in front of your pot.
That is not too complicated but not completely straightforward as you need to look at impedances (in and out) and also capacitive loads.
You could start trying experimenting easily with a few resistors to see if you like it until you find "your values". To make it simple, I would build it just before the volume pot with as short as possible wires, well noting a few inches aren't really a problem. But say inside the same casing or worst case in form of a plug between your RCA input cables and the B1 Korg's RCA inputs.
You will find lots of info on internet (voltage divider, attenuator are the key words), it is just 2 resistors per channel, one in the signal path, the other to ground, like a fixed volume pot.
As the 10k pot seemed to work fine otherwise, you could arrange your voltage divider to be a 10k set up and then go into your 50k pot (should given short distances though also work into your 10k pot).
The values of the resistors will determine impedance and attenuation. How much you want to "spread" your volume control to be comfortable depends entirely on you, but I would say iven your comments that you may want at least a 20dB attenuation network.
The sum of the 2 resistors will give you the impedance your source sees... and up to 1/4 of that value (so in most cases much less) the impedance your pot would see.
Good luck
Claude
EDIT: putting only a single resistor in the signal path could indeed work but given what your posted it would probably need to be a hell lot of Ohms and bring possibly other negative hence suggesting on my side a voltage divider as you really want to attenuate quite a lot. But just IMHO and I could be wrong...
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Keep the 10K ohm pot in. Add a 40K (or 39K) in series. This gets the circuit back to the original 50K load on the input. Now the max setting of the pot will be attenuated by 14dB. This is a simple experiment to try - pull up a wire on each side and put a resistor in series. Five minute effort. If no good - then go back. No reason that this shouldn't work. Others have commented that 100Kohm pot works OK in B1K. Assuming the 10K pot, the series resistor could be increased to 90K. This gives attenuation of 20dB at max pot setting.
if KB1 is having excessive gain for someone's needs, it is time for some other line stage, with lesser or no gain
it is a sacrilege wasting input signal amplitude in input attenuator, just to later amplify it
sugar gotten from KB1 is achievable in other ways
see "What is gain structure"
it is a sacrilege wasting input signal amplitude in input attenuator, just to later amplify it
sugar gotten from KB1 is achievable in other ways
see "What is gain structure"
Original kit is with 50K log type potentiometer..not linear type ,so is make difference.
Do some research Logarithmic Attenuator Calculator