Hmm... I don't think changing the pot value will alter the gain. Pots are voltage dividers: all a matter of ratios. Giving you a different adjustment range / feel is more a matter of lin vs log.
The pot impedance though plays a role in the load your source sees (easy to drive or less so if a 10k pot), possibly some noise due the pot resistance (Johnson noise, have yet to hear a real difference, I hear more differences between pots regardless the value with a good source due to the construction or make) and finaly it also impacts the way you load the B1 Korg. That load often varies with conventional pot, depends on the volume you set.
Apparently the B1 Korg wants to see some load, so 10k is probably as low as you want to go as it is likely to load the B1 korg with 2.5k (or so ) on some positions.
Just IMHO
Claude
The pot impedance though plays a role in the load your source sees (easy to drive or less so if a 10k pot), possibly some noise due the pot resistance (Johnson noise, have yet to hear a real difference, I hear more differences between pots regardless the value with a good source due to the construction or make) and finaly it also impacts the way you load the B1 Korg. That load often varies with conventional pot, depends on the volume you set.
Apparently the B1 Korg wants to see some load, so 10k is probably as low as you want to go as it is likely to load the B1 korg with 2.5k (or so ) on some positions.
Just IMHO
Claude
A 10k volume potentiometer will always load the preceding stage with 10k, so I fail to see that as a problem. If the preceding stage is a CD player with nominal 2V rms output, the current through the 10k is just milliAmperes.
Regarding (input) load on the B-1 input I do not understand this. I have not finished my B-1 Kong I have to admit, but I have never experienced problems with volume potentiometers at the input. At the lowest positions the network on the JFET gate will be series connection 10u + 100 Ohms in parallel with the 221k, to ground. I fail to see that this can cause problems.
Regarding (input) load on the B-1 input I do not understand this. I have not finished my B-1 Kong I have to admit, but I have never experienced problems with volume potentiometers at the input. At the lowest positions the network on the JFET gate will be series connection 10u + 100 Ohms in parallel with the 221k, to ground. I fail to see that this can cause problems.
Well, you seem to understand so your worked out that a 10k volume potentiometer will, as you say, "always load the preceding stage with 10k"... so 5 times less than a 50k pot ;-)
Wether this affects or not the sound depends entirely on your source and its capability to drive the load, as said. Some sources, like one of mine I use daily, have an output that is biased for Class A with a certain value. Asking 5 times more current isn't a problem at all indeed, it will deliver no problem, but sadly no more in pure Class A (would though remain in Class A with a 20k pot). Again, you to decide if it is a sonic concern or not...
BUT my comments were different and around:
- your hopes to address whatever gain issue changing the pot's impedance, something I don't understand, but as long as you are confident with that, just go ahead...
- people reporting here the B1 Korg liking some load at the input and a 10k pot having been a problem to some. Hasn't Papa mentioned something in that direction on this thread, mentioning a load of a few k could be a problem? How much is too low, no clue, you to find out... all I know is that your pot's output impedance will vary with volume setting and be as said way lower than 10k.
Mate, if you are sure and have already purchased the parts, just go ahead: there is nothing that can go wrong, worst case you just don't get the benefits you hope. Let us know your findings and I wish you the best
Claude
Wether this affects or not the sound depends entirely on your source and its capability to drive the load, as said. Some sources, like one of mine I use daily, have an output that is biased for Class A with a certain value. Asking 5 times more current isn't a problem at all indeed, it will deliver no problem, but sadly no more in pure Class A (would though remain in Class A with a 20k pot). Again, you to decide if it is a sonic concern or not...
BUT my comments were different and around:
- your hopes to address whatever gain issue changing the pot's impedance, something I don't understand, but as long as you are confident with that, just go ahead...
- people reporting here the B1 Korg liking some load at the input and a 10k pot having been a problem to some. Hasn't Papa mentioned something in that direction on this thread, mentioning a load of a few k could be a problem? How much is too low, no clue, you to find out... all I know is that your pot's output impedance will vary with volume setting and be as said way lower than 10k.
Mate, if you are sure and have already purchased the parts, just go ahead: there is nothing that can go wrong, worst case you just don't get the benefits you hope. Let us know your findings and I wish you the best
Claude
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Hi Claude
Thank you for the reply. We seem to agree really. Especially with regard to the load on the preceding stage.
Regarding the load from the potentiometer to the Korg, I believe people, even if I do not understand. 🙂 I will report whatever I find when the unit is ready.
Merry Christmas Claude et al.
Thank you for the reply. We seem to agree really. Especially with regard to the load on the preceding stage.
Regarding the load from the potentiometer to the Korg, I believe people, even if I do not understand. 🙂 I will report whatever I find when the unit is ready.
Merry Christmas Claude et al.
@ Citronone
Bravo your B1K it's play music
After B1 with Korg Nutube - diyAudio Guides
some work need be made about fighting microphonic.
Easy check steps 55,56
Proper chassis for this preamp is necessairy.
A year ago my B1K first play with 50K Alps stereo volume potentiometer.
All was OK but by curiosity change them for two mono 10K wire wound Spectrol potentimeters find in drawers.
I like it very much so in next step bough two mono new 50K Spectrols and two wernier knobs from Mouser.
I use them now and very satisfy.
After reading B1K FW page article , 332K plate resistor and 16dB gain numbers
was the best Mr.Pass
choice for desired sound harmonic content.
ClaudeG / R-K Rønningstad: I have payed for a 10K, will try it but baby not that much diference? Maby I dont like the logarytmic pots, maby try my Glasshouse stepped liniare shunt 20K as I use in my B1.
Soundhappy: I can not wait for chassie for my B1K, so I made some after work today. Only backplate left, do it tomorrow. I put it upside down over my B1K and no 5K ringing
Frank
Soundhappy: I can not wait for chassie for my B1K, so I made some after work today. Only backplate left, do it tomorrow. I put it upside down over my B1K and no 5K ringing
Frank
Attachments
@ Sagen
Hey that is fantastic DIY chassis
Bravo!
Hoho Pass B1 Triode play together with classA Hiraga amp 😀 Cool
Kristina - Santa Baby on Vimeo
Hey that is fantastic DIY chassis
Bravo! Hoho Pass B1 Triode play together with classA Hiraga amp 😀 Cool
Kristina - Santa Baby on Vimeo
@ Batty
Oh yeah with all M2X different front end boards to try and B1K trimmers H2 adjustements
this open a lots of possibilitys to find the one(s) favourite(s)
What is your T7 is T8 voltage choice with M2X ?
(HD) Kylie Minogue - Santa Baby on Vimeo
Oh yeah with all M2X different front end boards to try and B1K trimmers H2 adjustements
this open a lots of possibilitys to find the one(s) favourite(s)
What is your T7 is T8 voltage choice with M2X ?
(HD) Kylie Minogue - Santa Baby on Vimeo
I have a novice question. One of 100-Ohm resistors in my kit measured 88-Ohm, so I skipped installing the output resistors in both channels for now. I need to buy two 100-Ohm resistors to install there. I don't know what brand or type the kit resistors are plus kits may be different. So my question is simple. Can someone please recommend what high sound quality resistors I can get from Mouser? Sorry, I know very little about resistors 🙂
If it is the output resistor then it is of no worry at all, 100R being just a standard value and nothing critical.
Don't worry either about channel imbalance as what matters is the total load the output sees and that is likely to be several K, so a 12 Ohm difference don't really matter but in our mind
All IMHO
Claude
Don't worry either about channel imbalance as what matters is the total load the output sees and that is likely to be several K, so a 12 Ohm difference don't really matter but in our mind
All IMHO
Claude
I've replaced the Nutube in my B1K after the heater wire in the first one snapped. No magic smoke on switching on and that lovely glow is present on both sides!
I've set T7 and T8 at around 11.5V for the warm up phase. T1, T3, T4 all measure at the right levels. My only cause for concern is that T5 and T6 measure differently, T5 = 0.65V and T6 = 0.7V. I'm sure that they were roughly equal with the original nutube at around 0.65V. I note from the nutube's datasheet that it will cope with up to 0.8V, so I'm not worried on the that front.
Is this an issue or am I worrying unnecessarily?
Merry Christmas Everyone!
I've set T7 and T8 at around 11.5V for the warm up phase. T1, T3, T4 all measure at the right levels. My only cause for concern is that T5 and T6 measure differently, T5 = 0.65V and T6 = 0.7V. I'm sure that they were roughly equal with the original nutube at around 0.65V. I note from the nutube's datasheet that it will cope with up to 0.8V, so I'm not worried on the that front.
Is this an issue or am I worrying unnecessarily?
Merry Christmas Everyone!
Thanks 6L6,
My mind is now at rest!
I've plugged it in to the office rig and it is now playing music. I have to admit to being a little anxious about switching it on this time. I don't mind losing a couple of 50p components, but £50 in one part is a different matter!
Have a great day tomorrow!
My mind is now at rest!
I've plugged it in to the office rig and it is now playing music. I have to admit to being a little anxious about switching it on this time. I don't mind losing a couple of 50p components, but £50 in one part is a different matter!
Have a great day tomorrow!
Merry Christmas, Happy holidays, happy new years
avdesignguru
soundhappy
6l6
Papa!
and all of you. This has been a tough year. But this year allowed me to finish myB1 and F6 amps. I am grateful for your genegrousity. I wish that the whole world can respect diverse opionons and learn to accept and agree upon meaningful solutation to our challenges. That's how I was able to finish my projects...team work!
Thanks and have youself a wonderful holiday season
avdesignguru
soundhappy
6l6
Papa!
and all of you. This has been a tough year. But this year allowed me to finish myB1 and F6 amps. I am grateful for your genegrousity. I wish that the whole world can respect diverse opionons and learn to accept and agree upon meaningful solutation to our challenges. That's how I was able to finish my projects...team work!
Thanks and have youself a wonderful holiday season
Hi everybody,
I just received my Korg B1 kit and have a couple of newbie type questions before I start putting it together.
First, one of my 475 ohm resistors only measures 297.8 ohms. Is this something I should replace before I start or does it not matter? (The other 475R is 476.4.)
Second, when I measure my 9.1V zener diode I see Uf= 804mV. Could someone please help me decipher what this means? Is this number even remotely in the ballpark?
Thanks.
I just received my Korg B1 kit and have a couple of newbie type questions before I start putting it together.
First, one of my 475 ohm resistors only measures 297.8 ohms. Is this something I should replace before I start or does it not matter? (The other 475R is 476.4.)
Second, when I measure my 9.1V zener diode I see Uf= 804mV. Could someone please help me decipher what this means? Is this number even remotely in the ballpark?
Thanks.
Just build first PSU filtering part with 9V1 zener and test if all OK like in the build guide : from steps 37 to 43
B1 with Korg Nutube - diyAudio Guides
297R is strange..too low.
475R - + 1% resistors are important they need be the same or very close R value pair
= the same cathodes = filaments heaters current ~ 17mA~ 18mA.
See FW article extract source: http://www.firstwatt.com/pdf/art_diy_nutube_preamp.pdf
My 475R was carefuly tested and mached the best pair chosen from 20 pcs.
Enjoy