I think so many Diyers make the same "" fun ""..and complain..
Why move the preamp in operation ?....
Twin triode are not make to be shaked, please give them a rest.
Why removed the cover ?
Just put the cover back and enjoy the music without microphonic.
All RCA cable and ground connections ( volume potentiometer included ) are verified ok ?
Edit: You need to use some volume knob , on the photo the potetiometer is without.
Try reverse connections at the preamp outputs..
sound the same or different ? What is your favorite ?
Well done B1K DIY work
CongratulationsHi Octopus Technicus,
A few ideas...
1) Does your source (DAC or PC or whatever) enable phase inversion? That is often the case. If so, to get absolute polarity without inverting the LS cables, you could have both negative H2 AND absolute polarity by simply invert phase at the soure and RUN A HIGHER bias voltage. Instead of adjusting from under the H2 null point (somewhere around 11.5V), adjust symmetricaly higher than the H2 null point. For example, if your null point is 11.5V and you like the 10V setting, adjust then at 13V instead of 11.5V and invert phase at the source.
Whatever, you can adjust the bias to your liking, that's the purpose, my point being then higher than the null point (seems to be between 11 and 12V for most of us).
2) Nutube vibs. Has been treated already in this thread. IMHO, if it is only when you move the B1K or take the cover off... leave things as they are, you are fine! And stop caressing or undressing it, LOL!
Jokes aside, it is not meant to run like that.
Further, if you want to know if vibs can be attenuated with another Korg mount or whatever fancy solution, why not first trying something easy and reversible at Korg chip level? Say Blu-Tack at chip level, or Jim's famous eraser? Or Blu-tack under the board to see if less flex is better.
And if that doesn't help really, then casing, casing feet, board feet etc.
3) Tuner bit. Difficult one to adress. Shielding is your friend. Many threads on that, it is best to refer to them, it is NOT B1K specific, and it could also involve cabling to your active spealers or to the B1K etc.
Trying is better than theory, unless you have a great scope and you know what you are doing. As you posted it is perhaps not the case so just follow hints from other threads in hope it helps resolving the problem. Note a quick fix is also already stated in 1) , eg. stop touching it
Have a nice week and congrats for your build
Claude
A few ideas...
1) Does your source (DAC or PC or whatever) enable phase inversion? That is often the case. If so, to get absolute polarity without inverting the LS cables, you could have both negative H2 AND absolute polarity by simply invert phase at the soure and RUN A HIGHER bias voltage. Instead of adjusting from under the H2 null point (somewhere around 11.5V), adjust symmetricaly higher than the H2 null point. For example, if your null point is 11.5V and you like the 10V setting, adjust then at 13V instead of 11.5V and invert phase at the source.
Whatever, you can adjust the bias to your liking, that's the purpose, my point being then higher than the null point (seems to be between 11 and 12V for most of us).
2) Nutube vibs. Has been treated already in this thread. IMHO, if it is only when you move the B1K or take the cover off... leave things as they are, you are fine! And stop caressing or undressing it, LOL!
Jokes aside, it is not meant to run like that.
Further, if you want to know if vibs can be attenuated with another Korg mount or whatever fancy solution, why not first trying something easy and reversible at Korg chip level? Say Blu-Tack at chip level, or Jim's famous eraser? Or Blu-tack under the board to see if less flex is better.
And if that doesn't help really, then casing, casing feet, board feet etc.
3) Tuner bit. Difficult one to adress. Shielding is your friend. Many threads on that, it is best to refer to them, it is NOT B1K specific, and it could also involve cabling to your active spealers or to the B1K etc.
Trying is better than theory, unless you have a great scope and you know what you are doing. As you posted it is perhaps not the case so just follow hints from other threads in hope it helps resolving the problem. Note a quick fix is also already stated in 1) , eg. stop touching it
Have a nice week and congrats for your build
Claude
Max: does the "tuner" issue arise when you touch anywhere on the case or only when you touch the shaft of the volume pot?
The tuner effect is when I touch anywhere on the enclosure, it is louder when I touch the shaft of the pot especially when I turn the pot. and full signal amplified signal when I touch Aout on the PCB of the Pot, my phone is normally near me. I will experiment with the phone tonight when I get home
Ok, switch phone off, leave it somewhere else to discard that.
Try also without shoes or socks as I don't know your floor etc. just to discard electrostatic.
Finaly, check if the casing has a proper contact with the volume pot housing: sometimes the paint of the casing can stop contact...
I hope this helps
Claude
Try also without shoes or socks as I don't know your floor etc. just to discard electrostatic.
Finaly, check if the casing has a proper contact with the volume pot housing: sometimes the paint of the casing can stop contact...
I hope this helps
Claude
Also be sure there is no WiFi equipment nearby -- router, AP, streamer, etc.
MHO is the holes on the pcb should be made a bit larger to accommodate more slobber around the pins….great idea for Z insertion socket…
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Thanks all for the suggestions,
I found the RF interference. I had toned out all ground with the multimeter and all sounded fine, but I put a test lead between the chassis and the board the RF inference went away. I removed some of the paint as suggested but that didn’t fix it, not sure why maybe because of the brass stand-off but that should be fine. I ended up putting a ground wire from one of the boards stand-off nuts to one of the stands-offs that is holding the wires in place on the side panel of the chassis.
All is quiet now, Tomorrow I’m going change the voltage to the tube to reverse the phase. And experiment what sound I like better, I’m very pleased with the sound as it is out of phase. It is starting to grow on me.
Again, thank you all for helping out. I Really appreciate it.
Good night,
Max
I found the RF interference. I had toned out all ground with the multimeter and all sounded fine, but I put a test lead between the chassis and the board the RF inference went away. I removed some of the paint as suggested but that didn’t fix it, not sure why maybe because of the brass stand-off but that should be fine. I ended up putting a ground wire from one of the boards stand-off nuts to one of the stands-offs that is holding the wires in place on the side panel of the chassis.
All is quiet now, Tomorrow I’m going change the voltage to the tube to reverse the phase. And experiment what sound I like better, I’m very pleased with the sound as it is out of phase. It is starting to grow on me.
Again, thank you all for helping out. I Really appreciate it.
Good night,
Max
I see he already found the problem but, as ClaudeG suggested, and especially with casings with pre-drilled holes (and subsequently painted) one always has to check for continuity from every point in the case. Always sand paper/emery cloth holes that come pre-drilled (usually not a problem with those thick aluminum cover plates, silver only).
I bought one of the Galaxy cases to build my B1, along with the removable, metal floor, and was astonished how little continuity there was all around the case. Even the Hammond cases I’ve bought have to have paint sanded away for good metal-to-metal contact except where one drills holes obviously.
I built my B1Ks in both a plastic case as well as a wood case and both times I had to use a grounding wire touching the front of the ALPS pots, connected to the signal ground, just so I didn’t get a buzzing every time I touched the pots to adjust the volume (good thing I use metal knobs or I never would have known anything was amiss).
The live&learn of building…..
Cheers
I bought one of the Galaxy cases to build my B1, along with the removable, metal floor, and was astonished how little continuity there was all around the case. Even the Hammond cases I’ve bought have to have paint sanded away for good metal-to-metal contact except where one drills holes obviously.
I built my B1Ks in both a plastic case as well as a wood case and both times I had to use a grounding wire touching the front of the ALPS pots, connected to the signal ground, just so I didn’t get a buzzing every time I touched the pots to adjust the volume (good thing I use metal knobs or I never would have known anything was amiss).
The live&learn of building…..
Cheers
Gain bit high
Hello. I've build an integrated amp using a B1 Korg as preamp, and a Sure AB 32321 (class D) power amp. System gain is a bit high @ 43 dB.
Lowering gain is probably easiest done on the preamp -no smd parts. Question: will doing so have any effect on the sound? And, I should be able to figure it out myself, but which resistors do I need to swap to lower gain...by some 10 dB I think.
Greets, Bart.
Hello. I've build an integrated amp using a B1 Korg as preamp, and a Sure AB 32321 (class D) power amp. System gain is a bit high @ 43 dB.
Lowering gain is probably easiest done on the preamp -no smd parts. Question: will doing so have any effect on the sound? And, I should be able to figure it out myself, but which resistors do I need to swap to lower gain...by some 10 dB I think.
Greets, Bart.
Nope, you can't change the gain of the B1K without changing its sonic signature.
The gain has been chosen by Papa for sonic reasons, it is indeed somewhat highish vs usual preamps, but that's part of the unit.
It is of course doable, as with all preamps, but in that particular case it probably has even more sonic impact - unless you are ready to depart from what Papa wanted of course.
I hope this helps
Claude
The gain has been chosen by Papa for sonic reasons, it is indeed somewhat highish vs usual preamps, but that's part of the unit.
It is of course doable, as with all preamps, but in that particular case it probably has even more sonic impact - unless you are ready to depart from what Papa wanted of course.
I hope this helps
Claude
J113, LSK170, 2SK170, and 2SK370 are all acceptable JFETs for use in the B1K.
See https://www.firstwatt.com/pdf/art_diy_nutube_preamp.pdf
There is a difference in output impedance between LSK/2SK (140 Ohm) and J113 (170 Ohm).
The Korg Nutube has much higher distortion than any of the JFETs, so the Korg has the most effect on the sound and the input buffer JFET is in the background.
See https://www.firstwatt.com/pdf/art_diy_nutube_preamp.pdf
There is a difference in output impedance between LSK/2SK (140 Ohm) and J113 (170 Ohm).
The Korg Nutube has much higher distortion than any of the JFETs, so the Korg has the most effect on the sound and the input buffer JFET is in the background.
The signature is a function of output, but you can attenuate the
input to the circuit if you like, including having a volume control...
Need a grounding scheme
I would appreciate some help with a “how to ground” question.
I’m finalizing a design for a power supply for my B1K (24V) which includes the Academy Audio volume control (+/-15V) to solve the following issues:
1. The specified wall-wart does not provide adequate current for all the capacitors in the supply chain on startup, and the ON led comes on, then turns off, then comes on again permanently which indicates that the power supply’s short-circuit detection is reading the capacitor load as a short-circuit and momentarily shutting down before resuming.
2. The floating module which converts 24V to +/-15V works OK but there is no hash filter at the output so is probably delivering voltage with 50mv p-p hash riding in it.
3. Space in the diyaudio store chassis is limited, especially with my third pcb that deals with input & output relays, trigger circuit, etc.
So, I have come up with the single-board power solution as in the attached image.
1. Input surge is solved with current limiting resistors and relays that short them out after initial voltage has reached a reasonable (17v of 24, 9V of 15) level.
2. Added Mark Johnson’s PO89ZB hash filter to all outputs -- the 24V and both 15V.
3. Made the board as small as possible, and shaped it to fit along the side of the chassis with outputs at the right locations to minimize wiring. The board is 5.175 inches x 1.15 inches.
So, now I have to figure out grounding – considering the other wiring of the B1K, which input grounds and output grounds on this board should I connect together and which should remain isolated. The output of the dc dc converter module is floating (not connected to the module’s input ground), and what to do with this is my question.
Ways to deal with this could be a) split the ground plane as required and/or connect the various pcb ground points with traces in the appropriate manner.
I’m scratching my head and I don’t want to mess this up so any help would be very welcome.
I would appreciate some help with a “how to ground” question.
I’m finalizing a design for a power supply for my B1K (24V) which includes the Academy Audio volume control (+/-15V) to solve the following issues:
1. The specified wall-wart does not provide adequate current for all the capacitors in the supply chain on startup, and the ON led comes on, then turns off, then comes on again permanently which indicates that the power supply’s short-circuit detection is reading the capacitor load as a short-circuit and momentarily shutting down before resuming.
2. The floating module which converts 24V to +/-15V works OK but there is no hash filter at the output so is probably delivering voltage with 50mv p-p hash riding in it.
3. Space in the diyaudio store chassis is limited, especially with my third pcb that deals with input & output relays, trigger circuit, etc.
So, I have come up with the single-board power solution as in the attached image.
1. Input surge is solved with current limiting resistors and relays that short them out after initial voltage has reached a reasonable (17v of 24, 9V of 15) level.
2. Added Mark Johnson’s PO89ZB hash filter to all outputs -- the 24V and both 15V.
3. Made the board as small as possible, and shaped it to fit along the side of the chassis with outputs at the right locations to minimize wiring. The board is 5.175 inches x 1.15 inches.
So, now I have to figure out grounding – considering the other wiring of the B1K, which input grounds and output grounds on this board should I connect together and which should remain isolated. The output of the dc dc converter module is floating (not connected to the module’s input ground), and what to do with this is my question.
Ways to deal with this could be a) split the ground plane as required and/or connect the various pcb ground points with traces in the appropriate manner.
I’m scratching my head and I don’t want to mess this up so any help would be very welcome.
Attachments
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Never mind, I think I got it. In this case connect the floating ground to chassis ground because this application doesn't benefit from keeping it floating as long as it doesn't create a ground loop.
Lots of articles about how floating grounds allow esoteric solutions and unusual configurations and not many address a conventional application like this one.
Lots of articles about how floating grounds allow esoteric solutions and unusual configurations and not many address a conventional application like this one.