I have a question. I'm building a couple ACA amps and I need a preamp. I see the Korg Nutube B1 and the ACP+ are very popular. The Korg kits are out of stock but I can wait if needed as I'd prefer a complete kit vs. sourcing parts for an ACP+ build.
Thoughts on the difference? Ease of build? Sound differences? I'm assuming neither do balanced output xlr based on what I'm seeing (not a deal breaker).
Thoughts on the difference? Ease of build? Sound differences? I'm assuming neither do balanced output xlr based on what I'm seeing (not a deal breaker).
You could always use a pair of transformers to get true (equal impedance on each signal leg) balanced out. See Posts 5995 and 6001, although there are other posts throughout this thread. You would be looking for a line out transformer; 1:1 or 1:2 step-up depending upon what you are seeking in terms of distortion profile and the capability of the amp downstream.
Companies to look at include Jensen and Cinemag. I have not checked Edcor, but they might be the most economical choice with a reduction in fidelity, which may be acceptable depending upon your budget and hearing.
Remember that you will have to punch your own XLR holes in the DIYAudio chassis, if you decide to go that route, and there may not be much rook to do that!
Pass DIY Addict
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It will probably work just fine without the resistor 99.5% of the time.
My understanding of this practice is somewhat less than complete, but I believe it serves two purposes: 1) to prevent a short circuit in the event you inadvertently ground the output, thus providing a measure of safety, and 2) if prevents potential interaction of two devices that are connected simultaneously - one of them might provide some signal "bounce back" and the resistor limits this effect, thus preserving signal integrity.
If I am incorrect on this, I am sure that others with more knowledge can provide more details.
I'm just getting back into playing with audio and have ordered the Korg B1 PCB, FETS, and tube from the diyaudio store and the stuffing parts from Digikey.
I would like to ask a couple of questions; I tried to find answers but there are just too many pages to wade through in this thread.
First, I plan to replace the 50K volume control with a 10K LDR volume control (BTFSystems). Will I suffer dire audible consequences by making this switch?
Second, are there any obvious upgrades to the components listed on the BOM that would significantly improve the sound? I imagine the input and output capacitors could be upgraded at considerable expense but I am interested in the biggest bang for the buck, not too far out on the curve where price-performance gets flat.
Third, I cannot find the physical dimensions of the PCB anywhere. Could someone tell me what they are? I'm trying to figure out what size enclosure I need for this board plus the LDR board and IR & rotary encoder control board and input selector relay board.
Any comments appreciated.
I would like to ask a couple of questions; I tried to find answers but there are just too many pages to wade through in this thread.
First, I plan to replace the 50K volume control with a 10K LDR volume control (BTFSystems). Will I suffer dire audible consequences by making this switch?
Second, are there any obvious upgrades to the components listed on the BOM that would significantly improve the sound? I imagine the input and output capacitors could be upgraded at considerable expense but I am interested in the biggest bang for the buck, not too far out on the curve where price-performance gets flat.
Third, I cannot find the physical dimensions of the PCB anywhere. Could someone tell me what they are? I'm trying to figure out what size enclosure I need for this board plus the LDR board and IR & rotary encoder control board and input selector relay board.
Any comments appreciated.
The B1K doesn't care so much. 50K vs 10K has more to do with loading the source and noise. 10K will theoretically be less noise. I prefer 50K in my system, possibly due to loading the output impedance of my CD player.
The B1 sprung to life....with force! All voltages were spot on. Quiet as a mouse..the only issue is you just barely turn the potentiometer and POW..way to much volume....but it sounds good. I gotta start reading about what it takes to change this sensitive pot. I’m open to any suggestions.
Attachments
Good grief. I went all over that page and overlooked the numbers every time. Thank you for pointing out the obvious.
Monk55
If your pots are linear taper they will be too hot in the first part of their rotation.
If your pots are linear taper they will be too hot in the first part of their rotation.
Congratulations 🙂
Volume potentiometer for B1K are better logarithmic version like in original First Watt article. Thanks to Mr. Pass
Hello,
Since I don't get any replies in the analog line level forum I thought I'd ask the same question here since it's kind of B1K related too. I hope that's allowed and no one feels offended by this.
I'm currently designing an 5 source input board. Therefore I'd like to have one RCA and one XLR Input for each source. Is there a way to combine RCA and XLR Inputs without a physical switch or a jumper or a piece of wire inserted into the XLR Connector?
I found Rod Elliotts Circuit for a balanced line input circuit transforming balanced input to unbalanced output.
Source: Balanced I/O
Is it possible to wire the circuits output with the RCA Input connector? Obviously you should then only connect either RCA or XLR, but that's exactly the way I would like to have it.
Each channel would have one of these circuits for each left/right channel, which are then switched by relays on one unbalanced output. I have no problems with the relay channel switching. I just need to know if the above explained way of connecting XLR and RCA per channel per source together would work.
After the boards output a Muses Volume Control and the unbalanced B1K Preamplifier are planned.
Thanks in advance.
With best regards DosenZorn
Since I don't get any replies in the analog line level forum I thought I'd ask the same question here since it's kind of B1K related too. I hope that's allowed and no one feels offended by this.
I'm currently designing an 5 source input board. Therefore I'd like to have one RCA and one XLR Input for each source. Is there a way to combine RCA and XLR Inputs without a physical switch or a jumper or a piece of wire inserted into the XLR Connector?
I found Rod Elliotts Circuit for a balanced line input circuit transforming balanced input to unbalanced output.
Is it possible to wire the circuits output with the RCA Input connector? Obviously you should then only connect either RCA or XLR, but that's exactly the way I would like to have it.
Each channel would have one of these circuits for each left/right channel, which are then switched by relays on one unbalanced output. I have no problems with the relay channel switching. I just need to know if the above explained way of connecting XLR and RCA per channel per source together would work.
After the boards output a Muses Volume Control and the unbalanced B1K Preamplifier are planned.
Thanks in advance.
With best regards DosenZorn
two-way local selector per each input (choosing either Bal or SE) , then main SE 5way selector, feeding KB1?
yes
yes
I thought about that but I remember ordering Log pots specifically. I’m checking now. Thanks for the reply’s!!
RE: upgrades to components... there always are parts you can change but whether or not they are upgrades to the base build is very much up to your ears and what is before and after the B1K. The parts in the diyaudio kits/BOM are high quality. What you do beyond that is a matter of your own personal tastes. This kit is pretty easy to swap parts out given the relatively small number of components, and that is a feature not a bug of DIY or diyaudio projects.
The one thing I'd strongly recommend is to start with the NuTube's bias setting. As Papa shows you in his article, that is a simple way to measurably and audibly change the sonic character of the preamp.
--Tom
Thanks for that suggestion, I've read the PDF and am curious to see what happens to the sound as I tune the bias. One question I had was that it appears that the BOM calls for a single-turn pot but many of the pictures I've seen posted show a multi-turn. Wondering if the adjustment is sensitive enough that I should get some multi-turn pots right away and install in lieu of the single turn. I'm thinking the 4-turn would be enough. Does that sound right?