Was lucky to get the entire morning off and couldn’t help listening to the B1 KORG… and get to the bottom of it, playing with the settings… Boys and toys J
My configuration is 0.5V output level and I have not inverted the phase at the output so I am assuming that below 12V I am running in conventional positive 2nd harmonic, and over that in the very strange land of negative 2nd harmonic.
I must say adjusting the second harmonic level, be it positive or negative, makes quite a nice impact. Then of course there is « positiveness » and « negativeness » (LOL). That means the B1 KORG is quite unique in terms of (« pure ») sonic adjustments : this is not just playing slightly with the bias of a power amp and of course not playing with bass and treble knobs / filters.
I tried a full range of different voltages, varying from 9.2V to 14.2V, spending quite a few hours on that.
To my ears, considering traditional positive 2nd harmonic, my prefered position was 9.8V. Now, considering negative 2nd harmonic, my prefered position was 13.9V. I don’t have an analyzer but what I perceived as being lowest distorsion level or where H2 seemed to null was somewhere between 11.5 and 12V (to my ears and in my mind !).
And now, the engineering in me hates to say that, but Papa got me again and managed to trick me : I hesitated somewhat but YES I LOVE negative second harmonics ! So after some fiddling I went for 13.9V (in my case I prefered to reach that value per defaut, settling finally on 13.88V and 13.89V). And that’s where it will stay !
Am I correct assuming there is nothing wrong running this unit at 13.9V instead of the default 9.5V ? Or will it wear faster, run really harder etc. ?
I could of course invert cables at the speakers, but then not at the headphone, so if running 13.9V is safe and good I would prefer to do so, not caring about / adressing absolute phase for the moment.
Now, if my understanding is correct, I seem to prefer « not too much » of dominating negative 2nd harmonic. I am assuming that at max 0.4- 0.5V output level I am alreay running at a lower overall distorsion level than at 1V. As I could in another test adjust that part, playing with gain after the unit, I must say I prefer it that way. That means not pushing the B1 KORG really much harder than 0.5V (say staying below 1V), which is perhaps strange as given the unit’s high gain I am using it mainly as… a spicy attenuator !
By going probably a tad lower 2nd harmonic than recommended by default (but then we were « invited » to play, weren’t we ?), I am reducing distorsions probably a bit more but more importantly I am probably liking a bit more third harmonics proportion vs 2nd harmonics then per default. Or say rather: a tad less dominant 2nd harmonics towards the 3rd harmonics, as my guess is 2nd harmonic is still quite largely dominant at my setting (is it at 13.9V ???). This is at last my assumption and understanding.
As for the sound differences, it is really like Papa said : negative H2 brings a feeling of airiness, space and precise positioning and also a quite enjoyable listening. More H2, be it positive or negative H2, brings a fuller bass and a softer drive and lesser definition to my ears. Less H2 level brings more definition, but less kick and possibly more dryness. In any case there are sweet spots and you don’t want to overdo it either way. By having negative H2 and not too much of it I managed to combine « spaciality to die for » with bass that kicks while maintaining enough resolution and having a low distorted « reasonable precision engineer HIFI » LOL !
Just my own feeling and my preference here. I hope to encourage you to play with the settings and to share your experience !
Claude
My configuration is 0.5V output level and I have not inverted the phase at the output so I am assuming that below 12V I am running in conventional positive 2nd harmonic, and over that in the very strange land of negative 2nd harmonic.
I must say adjusting the second harmonic level, be it positive or negative, makes quite a nice impact. Then of course there is « positiveness » and « negativeness » (LOL). That means the B1 KORG is quite unique in terms of (« pure ») sonic adjustments : this is not just playing slightly with the bias of a power amp and of course not playing with bass and treble knobs / filters.
I tried a full range of different voltages, varying from 9.2V to 14.2V, spending quite a few hours on that.
To my ears, considering traditional positive 2nd harmonic, my prefered position was 9.8V. Now, considering negative 2nd harmonic, my prefered position was 13.9V. I don’t have an analyzer but what I perceived as being lowest distorsion level or where H2 seemed to null was somewhere between 11.5 and 12V (to my ears and in my mind !).
And now, the engineering in me hates to say that, but Papa got me again and managed to trick me : I hesitated somewhat but YES I LOVE negative second harmonics ! So after some fiddling I went for 13.9V (in my case I prefered to reach that value per defaut, settling finally on 13.88V and 13.89V). And that’s where it will stay !
Am I correct assuming there is nothing wrong running this unit at 13.9V instead of the default 9.5V ? Or will it wear faster, run really harder etc. ?
I could of course invert cables at the speakers, but then not at the headphone, so if running 13.9V is safe and good I would prefer to do so, not caring about / adressing absolute phase for the moment.
Now, if my understanding is correct, I seem to prefer « not too much » of dominating negative 2nd harmonic. I am assuming that at max 0.4- 0.5V output level I am alreay running at a lower overall distorsion level than at 1V. As I could in another test adjust that part, playing with gain after the unit, I must say I prefer it that way. That means not pushing the B1 KORG really much harder than 0.5V (say staying below 1V), which is perhaps strange as given the unit’s high gain I am using it mainly as… a spicy attenuator !
By going probably a tad lower 2nd harmonic than recommended by default (but then we were « invited » to play, weren’t we ?), I am reducing distorsions probably a bit more but more importantly I am probably liking a bit more third harmonics proportion vs 2nd harmonics then per default. Or say rather: a tad less dominant 2nd harmonics towards the 3rd harmonics, as my guess is 2nd harmonic is still quite largely dominant at my setting (is it at 13.9V ???). This is at last my assumption and understanding.
As for the sound differences, it is really like Papa said : negative H2 brings a feeling of airiness, space and precise positioning and also a quite enjoyable listening. More H2, be it positive or negative H2, brings a fuller bass and a softer drive and lesser definition to my ears. Less H2 level brings more definition, but less kick and possibly more dryness. In any case there are sweet spots and you don’t want to overdo it either way. By having negative H2 and not too much of it I managed to combine « spaciality to die for » with bass that kicks while maintaining enough resolution and having a low distorted « reasonable precision engineer HIFI » LOL !
Just my own feeling and my preference here. I hope to encourage you to play with the settings and to share your experience !
Claude
Thanks Papa, so that's excellent news, I can enjoy negative phase even on headphones
Small changes in plate voltage are audible. I find I like 9.7 V and reversed loudspeaker wires to correct the signal polarity to what was recorded.
For headphones, I am listening to a Pete Millett NuHybrid Headphone Amp with substitute 332K plate resistors (thank you Papa) and 9.7 volts as well. To correct the polarity, I'm using Jensen JT11-P-1 input transformers with their primaries reversed.
Your comments confirm what I suspected but never tried, that going to the high side of half supply on the plates and not reversing the polarity can also work well. Probably could have saved some $$ by not adding transformers to the headphone amp!
Thanks Papa... yes I do.
With 13.9V I am negative 2nd harmonic but indeed inversed signal polarity, as posted.
Well... I can still either:
A- leave it like it is (not sure I hear absolute polarity nor that there is an absolute phase on recordings, will have to dig), so having negative 2nd harmonic both at louspeakers and headphone (same sound)
B- reverse the absolute phase at the source (kind of switching inside the DAC, have to dig aswell but persumably the easiest solution as switchable and also headphone compatible... but then no real solution for LPs other than trannies or inverting stages or going ADC)
C- reverse the phase with some power amp stages or conveniently as you recommended at the speaker's terminal by simply inverting the cables... and need output transformers or similar to get it at headphones from the B1 KORG
But in cases B and C I would end up with my 13.9V setting with indeed absolute phase BUT positive 2nd harmonic so that mean I would have to move my setting to presumably something around 9.8V to get the same sonic result as today, that is with negative 2nd harmonic again.
Papa, I have not yet played with absolute polarity so I don't know if that is really that is relevant (to me at least) in real music listening conditions and with real variety of recordings / records.
I hope my understanding is correct
And in any case many thanks again for the kind reminder
Claude
With 13.9V I am negative 2nd harmonic but indeed inversed signal polarity, as posted.
Well... I can still either:
A- leave it like it is (not sure I hear absolute polarity nor that there is an absolute phase on recordings, will have to dig), so having negative 2nd harmonic both at louspeakers and headphone (same sound)
B- reverse the absolute phase at the source (kind of switching inside the DAC, have to dig aswell but persumably the easiest solution as switchable and also headphone compatible... but then no real solution for LPs other than trannies or inverting stages or going ADC)
C- reverse the phase with some power amp stages or conveniently as you recommended at the speaker's terminal by simply inverting the cables... and need output transformers or similar to get it at headphones from the B1 KORG
But in cases B and C I would end up with my 13.9V setting with indeed absolute phase BUT positive 2nd harmonic so that mean I would have to move my setting to presumably something around 9.8V to get the same sonic result as today, that is with negative 2nd harmonic again.
Papa, I have not yet played with absolute polarity so I don't know if that is really that is relevant (to me at least) in real music listening conditions and with real variety of recordings / records.
I hope my understanding is correct
And in any case many thanks again for the kind reminder
Claude
NU Tube B1 Xmas board up and running! Initially I'm blown away by the sound! Frankly I was not expecting it can keep up with my 12B4A dual mono ultimate build preamp but in some aspects it is even better. Musicality, tonality are the first things to notice as strength. Of course absolute transparency and stage can not keep up with stepped attenuator having small 50cent pot for now, and probably some veiling by elcos in signal path... BUT its potential is so obvious that from the first moments I knew it is a keeper!!! It deserves a nice enclosure and proper attenuation.
All my voltages are in suggested ranges:
T1 23.85 vdc
T3 23.09vdc
T4 9.06 vdc
T5 0.623 vdc
T6 0.632 vdc
T7 9.55 vdc (after 1h)
T8 9.55 vdc (after 1h)
BIG thanks to Mr.Pass for this!!!
All my voltages are in suggested ranges:
T1 23.85 vdc
T3 23.09vdc
T4 9.06 vdc
T5 0.623 vdc
T6 0.632 vdc
T7 9.55 vdc (after 1h)
T8 9.55 vdc (after 1h)
BIG thanks to Mr.Pass for this!!!
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When I place a B1+Korg in front of a single stereo or dual mono ACA’s I hear too much of a good thing.
A good o’ll B1 w/o Korg in front of either on the other hand sounds spectacular.
Something else to consider..
I appreciate that advice. Right now I am totally new to the DIY audio thing. I'll likely build the Korg because it will be offered as a complete kit as the ACA is. As I get more comfortable with the hobby I may take your advice and try the B1 non-korg as a first try at a non-kit build. Eventually I would also like to build an F5 but even the PS for it seems daunting to me right now. Even just trying to understand and calculate what transformer and what CRC component values should be. And I certainly don't want to bore the long time builders with rookie questions. Heck, right now I don't know enough to figure out what term to put into the search function to resolve a question. But I'll get there!
start with writing what and in which form you want to build
then , with adequate replies , you'll know more and able to ask more
Thanks for the show of support folks.
I stumbled on the build thread 6L6 did on the F5. I'm learning a ton from that because that's the PS/Amp combination I want to build after the B1 Korg. But I'll post questions on that thread when I can't figure out things on my own on that build.
But let me ask this here, a LOT of the cost of these kits is in the Chassis. In the age of computer processors there are some very good and quiet solutions for chip cooling. Is the only reason these Chassis are so big is to dissipate the heat? If so, has anyone experimented PC type chip cooling in smaller enclosures? Heck, I have a HTPC in my rack right now anyway. It isn't causing a noise problem for me. The coolers aren't free either so I would expect the cost difference may not be that much but the size thing is a problem too. Just thinking...
I stumbled on the build thread 6L6 did on the F5. I'm learning a ton from that because that's the PS/Amp combination I want to build after the B1 Korg. But I'll post questions on that thread when I can't figure out things on my own on that build.
But let me ask this here, a LOT of the cost of these kits is in the Chassis. In the age of computer processors there are some very good and quiet solutions for chip cooling. Is the only reason these Chassis are so big is to dissipate the heat? If so, has anyone experimented PC type chip cooling in smaller enclosures? Heck, I have a HTPC in my rack right now anyway. It isn't causing a noise problem for me. The coolers aren't free either so I would expect the cost difference may not be that much but the size thing is a problem too. Just thinking...
I'm certainly impressed with the ACA. But for seriously dynamic music at higher gain levels you need two of them. I'm assuming an F5 would sound better than two bridged ACAs. I was also thinking of putting the PSU remotely in it's own box and use a smaller box for the amp itself. You wouldn't have to worry about the PSU magnetic fields either. But just thinking out loud.
I just finished reading this thread, taking notes, and ordering the PCB kit and a chassis, I'm in the purchasing phase.
I do have one question regarding a tube based source as an input, 6L6 made reference in regards to a question about input pot 20K, 50K, 100K. Is there anything different needed for the 6AX7a phono section as an input to the Korg?
I do have one question regarding a tube based source as an input, 6L6 made reference in regards to a question about input pot 20K, 50K, 100K. Is there anything different needed for the 6AX7a phono section as an input to the Korg?
