One could possibly use a H2 as an inverting stage to maintain absolute phase/correct polarity of the B1-Korg. But maybe too much second harmonic out of it.
Regds
Regds
Yes, I do remember you once said so, so no Mae West quote here “Too much of a good thing can be wonderful.”
Hi all
I've just ordered Pete Millets Korg board and tube, would have prefered to use the First Watt clone board but couldn't find them....
Question now is should I use Pete's component values or do we need to change things based on development experience? I have some spare LSK170's, would these be first choice?
Any advise for this build would be gratefully received. Already using the Mesmerize buffer and have an Aska Leader pre in the pipeline...... Sort of addicted to DIY.
Cheers Dave
I've just ordered Pete Millets Korg board and tube, would have prefered to use the First Watt clone board but couldn't find them....
Question now is should I use Pete's component values or do we need to change things based on development experience? I have some spare LSK170's, would these be first choice?
Any advise for this build would be gratefully received. Already using the Mesmerize buffer and have an Aska Leader pre in the pipeline...... Sort of addicted to DIY.
Cheers Dave
I asked Pete Millett this too. His response was:
If you to want use the JFETs instead of the bipolars in the buffer board to change drain resistors to 10K from 1 K
and add a 1K resistor in series with the gates to prevent oscillation.
Also as Nelson Pass has pointed out in previous posts you need to turn the JFET device around ie not matching the silkscreen since the source and drain leads are reversed compared to the bipolars.
I did it this way and it sounds fine.
If you to want use the JFETs instead of the bipolars in the buffer board to change drain resistors to 10K from 1 K
and add a 1K resistor in series with the gates to prevent oscillation.
Also as Nelson Pass has pointed out in previous posts you need to turn the JFET device around ie not matching the silkscreen since the source and drain leads are reversed compared to the bipolars.
I did it this way and it sounds fine.
I was just working on this today, and I'm swapping out some of the other components for the NP values, looking for something that might be able to match his gain and distortion results. If you look at the schematics side-by-side, the changes needed are apparent, and are relatively few in number. (Get some 221k resistors, always a good thing to have on hand for Nelson's projects.)
Chul is also doing this, and has posted (including some pics) in this thread.
Chul is also doing this, and has posted (including some pics) in this thread.
Is a NP-PCB without tubes OK?
I have a tubes, (it’s difficult when it’s dual and single🙂 ), just waiting.
I have a tubes, (it’s difficult when it’s dual and single🙂 ), just waiting.
The problem is simply one of time. I have allowed myself a wide
range of entertainments (=work), and so many things wait on the list.
range of entertainments (=work), and so many things wait on the list.
That "sounds good"....then I will still be patient and wait.....I have the NuTubes…..so no need to get the Pete Millett PCB and try to "tweak it".
Looks good!
What I like about the DIY store PCBs is that the seems very prof layout with solid ground....a lot of copper the "right" places to suppress noise.
What I like about the DIY store PCBs is that the seems very prof layout with solid ground....a lot of copper the "right" places to suppress noise.
Of course, this construction project doesn't work as well as one might hope if the parts stash turns out to have only 4 jfets. :-(
I plan to try this preamp with my M2 clone. Good idea? M2 has about 15dB gain as opposed to 20dB (Sony VFET), so do I need to play with the bias setting a bit?
Good enough idea. M2 is a 3rd harmonic beast, and the Korg will add 2nd.
It's great to be able to try anything and see what you get, but a lot of
people don't have that luxury. Anyone with a 2nd harmonic character
power amp would want to consider whether they want to play that
trick twice by adding the Korg or similar.
I'm just suggesting that we haven't yet reached a consensus on that...
It's great to be able to try anything and see what you get, but a lot of
people don't have that luxury. Anyone with a 2nd harmonic character
power amp would want to consider whether they want to play that
trick twice by adding the Korg or similar.
I'm just suggesting that we haven't yet reached a consensus on that...
Thanks. So, I tried Korg preamp with my M2 clone. Initially I set THD+N at about 1.5% at 1V output, but that was clearly too much. Then I changed it to about 1%, much better. I tried both negative phase (about 9V plate voltage) and positive phase (about 12V plate voltage) 2nd harmonic. First impressions - negative phase sounds to me a bit softer, less energy in bass, I kept turning volume up, positive phase a bit more shouty, better presence, stronger bas. Need to listen to it more...