Just remember that the Korg output is calibrated for about 1V and has
quite a lot of 2nd at 2V, and not a lot of headroom above that. I don't
know that a high current buffer is going to give you that, but I don't
see how it would hurt.
B1 NUTUBE start up
Hello forum members,
I started up the B1 NUTUBE today. No smoke! Still burning in without fire.
All seems to be o.k..
My values at the testpoints:
T1: 23.87 V
T2: 23.14 V
T3: 22.40 V
T4: 9.16 V
T5: 0.660 V
T6: 0.653 V
T7: adjusted to 9.5V
T8: adjusted to 9.5V
Waiting for the backpanel to do the finishing work. Perhaps a listening-test
this afternoon.
Have a great weekend!
Sun is shining in Germany
Greets Dirk
Hello forum members,
I started up the B1 NUTUBE today. No smoke! Still burning in without fire.
All seems to be o.k..
My values at the testpoints:
T1: 23.87 V
T2: 23.14 V
T3: 22.40 V
T4: 9.16 V
T5: 0.660 V
T6: 0.653 V
T7: adjusted to 9.5V
T8: adjusted to 9.5V
Waiting for the backpanel to do the finishing work. Perhaps a listening-test
this afternoon.
Have a great weekend!
Sun is shining in Germany
Greets Dirk
Attachments
No doubt but 6 dB would be nice. A LME 47600 will I try. Have bad exsperience with it but maybe ok in this circuit with much Second harmonics. It will hopefully cancel out the fuzzy sound of the 47600.
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I noticed that the FET buffer circuits used in the B1, the RC filter buffer sections of the LxMini analog crossover and the B1-Korg are a bit different. Could you explain the reasoning behind these differences?
Thx!
Attachments
All three are single-ended buffers, that is to say an N channel Jfet
follower which is biased by a constant current source.
The follower fet is a 2SK170, LSK170, or 2SK370 (same chip different
package) in the B1 and Korg. In those two, the current source is simply
the same part operated at Idss by connecting Gate and Source together.
Ideally the follower and CCS use the Jfets selected so that they are
either matched or for slightly lower Idss on the CCS.
In the LXmini buffer, we use J113's, with the CCS current set by the value
of Idss and the resistor to operate the follower at slightly less than it's
Idss figure.
We do this in order to avoid using the very expensive / unavailable
Jfets seen on the two other circuits. There is not doubt that the 2SK170
types are better, but in this application we can get similar performance
from selected J113's, - thd around 0.002% at 1V into 10 Kohm, with
negligible noise.
follower which is biased by a constant current source.
The follower fet is a 2SK170, LSK170, or 2SK370 (same chip different
package) in the B1 and Korg. In those two, the current source is simply
the same part operated at Idss by connecting Gate and Source together.
Ideally the follower and CCS use the Jfets selected so that they are
either matched or for slightly lower Idss on the CCS.
In the LXmini buffer, we use J113's, with the CCS current set by the value
of Idss and the resistor to operate the follower at slightly less than it's
Idss figure.
We do this in order to avoid using the very expensive / unavailable
Jfets seen on the two other circuits. There is not doubt that the 2SK170
types are better, but in this application we can get similar performance
from selected J113's, - thd around 0.002% at 1V into 10 Kohm, with
negligible noise.
answer to dtaylo3
Hello dtaylo3,
the case is from modushop Italy. Somewhere around 40 - 50 €. Plus shipping.
Shipping could be expensive to the states.
But it was a bare black anodized aluminum case.
The front window (where you see the NUTUBE) and all the cutouts, lettering,..
was made by me on a CAD-program you can get for free from SCHAEFFER AG
in Germany (same like 'front panel express' in the USA). I sent them the black 10mm frontpanel, my CAD-datas and they produced it for me.
Price 43,63€
The plexiglas was cutout and sanded by hand! I wanted a very close fit.
Also the aluminum bracket for the NUTUBE which has rubber dampers is made by me. Handwork and good tools. And time!
Greets
Dirk
Hello dtaylo3,
the case is from modushop Italy. Somewhere around 40 - 50 €. Plus shipping.
Shipping could be expensive to the states.
But it was a bare black anodized aluminum case.
The front window (where you see the NUTUBE) and all the cutouts, lettering,..
was made by me on a CAD-program you can get for free from SCHAEFFER AG
in Germany (same like 'front panel express' in the USA). I sent them the black 10mm frontpanel, my CAD-datas and they produced it for me.
Price 43,63€
The plexiglas was cutout and sanded by hand! I wanted a very close fit.
Also the aluminum bracket for the NUTUBE which has rubber dampers is made by me. Handwork and good tools. And time!
Greets
Dirk
B1 NUTUBE plays music
Hello friends of beautiful sound machines,
the B1 NUTUBE is playing music the first time. I put it on my DENON POA-2200 Amp and the cheap JBL CONTROL1 for a first test.
It's playing music! And this little critter seems to be a giant.
Will connect that babe tomorrow to my real system.
But this little test and burn in is more than promising!
Greets
Dirk
Hello friends of beautiful sound machines,
the B1 NUTUBE is playing music the first time. I put it on my DENON POA-2200 Amp and the cheap JBL CONTROL1 for a first test.
It's playing music! And this little critter seems to be a giant.
Will connect that babe tomorrow to my real system.
But this little test and burn in is more than promising!
Greets
Dirk
Attachments
Although my build is beginner cartoon-ish, I am just glad it works and sounds great. I think by sound quality the Pass Korg deserves the best chassis and build one can give it.
I had some 'growing pains' with mine. A couple of bad solder joints and crackling. I took the board out, examined everything, touched up several solder points. When I re-tested the board, and put screwdriver to L bias adjustment pot, L filament went out. I took the board out, re-soldered the bias pot, and re-assembled. Complete silence and all crackles and pops gone, soldering sins penanced, and all is well.
I finally deemed it tested and complete, I screwed the top panel on, and Pass Korg is now doing (semi?) permanent service as a gain stage equalizer for my midrange ribbon (active crossover system four way) and it sounds mah-valuss, and oh so quiet. The ribbon needs phase reversal from the crossover, so I think it is operating in H2 negative, but H2 positive is great, too.
I would love to try to build a SissySit, but that is a cosmic leap from this project. I will have to 'mental task' the SissySit through by concept and parts first and see if I have the cojones to attempt, and accept the possibility of abject failure.
I had some 'growing pains' with mine. A couple of bad solder joints and crackling. I took the board out, examined everything, touched up several solder points. When I re-tested the board, and put screwdriver to L bias adjustment pot, L filament went out. I took the board out, re-soldered the bias pot, and re-assembled. Complete silence and all crackles and pops gone, soldering sins penanced, and all is well.
I finally deemed it tested and complete, I screwed the top panel on, and Pass Korg is now doing (semi?) permanent service as a gain stage equalizer for my midrange ribbon (active crossover system four way) and it sounds mah-valuss, and oh so quiet. The ribbon needs phase reversal from the crossover, so I think it is operating in H2 negative, but H2 positive is great, too.
I would love to try to build a SissySit, but that is a cosmic leap from this project. I will have to 'mental task' the SissySit through by concept and parts first and see if I have the cojones to attempt, and accept the possibility of abject failure.
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I was planning on using the Korg B1 as a buffer with gain. I have no intention of adding a volume pot. I am just using it to get some gain (more than I need, actually) and the tube sound. Going from DAC to Korg B1 then to amp, with volume control at source.
Does this affect my implementation?