First of all, thank you Nelson Pass and the DIY Audio store and community at large.
I have read this thread from the beginning and have started to read it again.
I am a recipient of the store completion kit with chassis, and will share my findings here.
(1) there is definite hiss/distortion present through the speakers from the B1K.
(2) don’t over tighten the switches: I wrecked one of the switches supplied with the kit when I over torqued the nut and it ripped the guys out (part number would be appreciated).
(3) the BOM supplied tested correctly and installed easily.
I have read this thread from the beginning and have started to read it again.
I am a recipient of the store completion kit with chassis, and will share my findings here.
(1) there is definite hiss/distortion present through the speakers from the B1K.
(2) don’t over tighten the switches: I wrecked one of the switches supplied with the kit when I over torqued the nut and it ripped the guys out (part number would be appreciated).
(3) the BOM supplied tested correctly and installed easily.
Thanks for the feedback. If I can get my son to bring it over I'll check it out.
David
Bi Korg with M2x
Thanks Nelson and everyone else on the thread for the terrific project. Built the preamp a few days ago and have been running it constantly since then. The M2x with the Tucson(opa1612) board sounds fantastic with it on everything I put on, from rock to classical. Did use Muse 1000 uf caps and 25K mono gold point attenuators. Hard to describe the sound but Nelson describing the 95 setting as intimate I think is on the mark. Thanks again.
Thanks Nelson and everyone else on the thread for the terrific project. Built the preamp a few days ago and have been running it constantly since then. The M2x with the Tucson(opa1612) board sounds fantastic with it on everything I put on, from rock to classical. Did use Muse 1000 uf caps and 25K mono gold point attenuators. Hard to describe the sound but Nelson describing the 95 setting as intimate I think is on the mark. Thanks again.
... and now for something completely different
This is a B1 Korg build using the Xmas board and matched set of Toshiba JFets. Many thanks to Papa Nelson!
I had a full plate of other amp builds earlier in the year, so wasn't in a big hurry to build the B1 Korg preamp right away. I thought about some of the other options for chassis, volume & switching controls, then realized that a quality donor chassis would be a nice way to go. The Naim NAC 62 preamp is a great entry level preamp which fits in nicely with the rest of my system. It also happens to have plenty of room for the B1 Korg PCB. This ended up going very well. The basic NAC 62 circuit consists of a set of line level inputs (plus phono with extra gain & eq board), followed by a selector switch which feeds an initial buffer stage. Next are the volume and balance controls and finally a pair of amplifier circuits that provide the overall gain for the preamp. The power supply is external, and may come from one of the smaller Naim amplifiers (NAP 140, 150, etc) or a separate HiCap supply.
I constructed my preamp so the B1 Korg replaced the final gain stages, keeping the rest of the buffer, volume and balance circuits intact. I did take the opportunity to upgrade the coupling caps in the buffer to 2.2 uF Nichicon ES series caps on the input and 10 uF Elna Silmics on the output. The NAC 62 allows for two regulated +24V power supplies, split between the low level and high level gain stages. I took advantage of this to give the B1 Korg a +24V rail that is separate from the input buffer.
I kept the B1 Korg build pretty much according to spec (weird, I know), using 1000 uF, 35V Nichicon KA series caps for the first four positions in the boards local supply, and 1000 uF, 25V Nichicon KW series for the local channel supply decoupling. Initial voltage checks showed things to be in the proper range, and I set the T7 & T8 voltages to 11.75V to keep harmonic content fairly clean. My HP 339 distortion analyzer shows about 0.03% THD while the output of the preamp is producing 4V p-p.
The Naim preamp is housed in a sturdy chassis which is designed to offer some isolation from external vibration. The PCB has large piece of foam rubber underneath the buffer and gain stages, and an external one piece heavy aluminum box which slides over the U-channel base plate which houses front and rear controls & connectors. I mounted the B1 Korg PCB onto the main PCB with a pair of left over foam pieces from the interior of a Pelican case, using double sided foam tape to hold everything securely in place.
The extra measures to isolate the Korg Nutube from vibration paid off. While the case was open during initial testing and bias set, I tapped directly on the Korg PCB and observed a brief 5kHz signal riding on my 1kH test tone. After the case was all buttoned up, tapping on the outside produced no noticeable ringing artifacts at my speakers.
I have been running the new B1 Korg62 with my old HiCap power supply that was replaced with a custom unit that I built for my NAC 82. Source is a Naim XCD2 with another custom PSU, power amp is my Aleph J, and speakers are my venerable Vandersteen 2C. The B1 Korg combo is very pleasant to listen to, much like another good tube preamp that I have. There is no noticeable hum and only the slightest amount of hiss which is barely detectable with an ear next to the speaker. Initial tonal presentation was somewhat forward, but this became more relaxed as the new preamp broke in. In addition to the integrity of harmonic structure that I am accustomed to with Naim gear, the B1 Korg presents music with an engaging sense of flow. Again, one of the things I appreciate about better tube electronics.
Though it is somewhat unfair to compare this preamp to my reference NAC 82, for the much the same reason as comparing it to a Pass Labs XP-22, the B1 Korg does remarkably good job. Where the 82 – Aleph J combination is positively uncanny at imaging, presence and detail, the B1 Korg is simply excellent. And that excellence makes for a wonderful listening experience.
This is a B1 Korg build using the Xmas board and matched set of Toshiba JFets. Many thanks to Papa Nelson!
I had a full plate of other amp builds earlier in the year, so wasn't in a big hurry to build the B1 Korg preamp right away. I thought about some of the other options for chassis, volume & switching controls, then realized that a quality donor chassis would be a nice way to go. The Naim NAC 62 preamp is a great entry level preamp which fits in nicely with the rest of my system. It also happens to have plenty of room for the B1 Korg PCB. This ended up going very well. The basic NAC 62 circuit consists of a set of line level inputs (plus phono with extra gain & eq board), followed by a selector switch which feeds an initial buffer stage. Next are the volume and balance controls and finally a pair of amplifier circuits that provide the overall gain for the preamp. The power supply is external, and may come from one of the smaller Naim amplifiers (NAP 140, 150, etc) or a separate HiCap supply.
I constructed my preamp so the B1 Korg replaced the final gain stages, keeping the rest of the buffer, volume and balance circuits intact. I did take the opportunity to upgrade the coupling caps in the buffer to 2.2 uF Nichicon ES series caps on the input and 10 uF Elna Silmics on the output. The NAC 62 allows for two regulated +24V power supplies, split between the low level and high level gain stages. I took advantage of this to give the B1 Korg a +24V rail that is separate from the input buffer.
I kept the B1 Korg build pretty much according to spec (weird, I know), using 1000 uF, 35V Nichicon KA series caps for the first four positions in the boards local supply, and 1000 uF, 25V Nichicon KW series for the local channel supply decoupling. Initial voltage checks showed things to be in the proper range, and I set the T7 & T8 voltages to 11.75V to keep harmonic content fairly clean. My HP 339 distortion analyzer shows about 0.03% THD while the output of the preamp is producing 4V p-p.
The Naim preamp is housed in a sturdy chassis which is designed to offer some isolation from external vibration. The PCB has large piece of foam rubber underneath the buffer and gain stages, and an external one piece heavy aluminum box which slides over the U-channel base plate which houses front and rear controls & connectors. I mounted the B1 Korg PCB onto the main PCB with a pair of left over foam pieces from the interior of a Pelican case, using double sided foam tape to hold everything securely in place.
The extra measures to isolate the Korg Nutube from vibration paid off. While the case was open during initial testing and bias set, I tapped directly on the Korg PCB and observed a brief 5kHz signal riding on my 1kH test tone. After the case was all buttoned up, tapping on the outside produced no noticeable ringing artifacts at my speakers.
I have been running the new B1 Korg62 with my old HiCap power supply that was replaced with a custom unit that I built for my NAC 82. Source is a Naim XCD2 with another custom PSU, power amp is my Aleph J, and speakers are my venerable Vandersteen 2C. The B1 Korg combo is very pleasant to listen to, much like another good tube preamp that I have. There is no noticeable hum and only the slightest amount of hiss which is barely detectable with an ear next to the speaker. Initial tonal presentation was somewhat forward, but this became more relaxed as the new preamp broke in. In addition to the integrity of harmonic structure that I am accustomed to with Naim gear, the B1 Korg presents music with an engaging sense of flow. Again, one of the things I appreciate about better tube electronics.
Though it is somewhat unfair to compare this preamp to my reference NAC 82, for the much the same reason as comparing it to a Pass Labs XP-22, the B1 Korg does remarkably good job. Where the 82 – Aleph J combination is positively uncanny at imaging, presence and detail, the B1 Korg is simply excellent. And that excellence makes for a wonderful listening experience.
Attachments
Hi everyone
I got questions
What is the j113 for and what if I have 2sj74?would it be better or just use j113?
Which pair have to matched? And what are the penalties.
Sorry I had to ask because i found bit and pieces of the info and still abit confused.
Mr Nelson, saw the videos with Steve Guttenberg. And I had a real good times with all your stories. I had shared the videos with all my friends.
I got questions
What is the j113 for and what if I have 2sj74?would it be better or just use j113?
Which pair have to matched? And what are the penalties.
Sorry I had to ask because i found bit and pieces of the info and still abit confused.
Mr Nelson, saw the videos with Steve Guttenberg. And I had a real good times with all your stories. I had shared the videos with all my friends.
Just a quick update on my B1 Korg build.
After having the unit powered on continuously for the last three days or so, I sat down for another listen this morning. The preamp has transformed from being simply excellent to entering positively uncanny territory. This little design is seriously sounding better than it has any right to. Imaging now extends slightly beyond the speakers, and transparency has opened up to reveal more details of well recorded acoustic and electric instruments. Really amazing.
The Aleph J also continues to impress me with how good it sounds. A small tweak to the power supply about a week ago seems to be a contributing factor.
After having the unit powered on continuously for the last three days or so, I sat down for another listen this morning. The preamp has transformed from being simply excellent to entering positively uncanny territory. This little design is seriously sounding better than it has any right to. Imaging now extends slightly beyond the speakers, and transparency has opened up to reveal more details of well recorded acoustic and electric instruments. Really amazing.
The Aleph J also continues to impress me with how good it sounds. A small tweak to the power supply about a week ago seems to be a contributing factor.
Thanks everyone for their help, especially 6L6. I finished the preamp and everything tests perfectly. However, I won’t be able to do any listening tests until this evening. I am going to try it out with my Pass DIY Sony VFET amp and my McIntosh MC240 tube amp.
Construction of the amp was straightforward as I used my own wire rather than the kit-supplied CAT-5 wire. Everything else is stock as supplied in the kits. As usual, the chassis is impeccably made and easy to assemble.
Construction of the amp was straightforward as I used my own wire rather than the kit-supplied CAT-5 wire. Everything else is stock as supplied in the kits. As usual, the chassis is impeccably made and easy to assemble.
I have had a Korg B1 awaiting a opportunity to be built for me.
A friend now has time on his hands, and is willing to put this together for me.
It would be much appreciated if I could receive any pointers on improving on what I believe is the basic build version.
I am not a EE minded person, I will have my friend review any offerings of advice.
A friend now has time on his hands, and is willing to put this together for me.
It would be much appreciated if I could receive any pointers on improving on what I believe is the basic build version.
I am not a EE minded person, I will have my friend review any offerings of advice.
I really like the Duelund DCA20GA cotton-insulated Tin-plated Copper wire for internal hook-up wire and interconnect cables. For the DC power, I use Kimber Kable TCSS Teflon-insulated stranded Copper wire. Does it make a difference? I like it, and that’s what matters most to me.
I did wire the LED backwards, but fixed that. That was just a careless error on my part. Anyway, I am looking forward to listening to this in my system. I am traveling to my old stomping grounds in the San Francisco Bay Area, and some of my audio buddies there have asked me to bring it along for auditions in their respective systems. The nice compact and sturdy chassis will fit well in my luggage.
I’m going to try and make to this year’s BAF in San Francisco too.
I did wire the LED backwards, but fixed that. That was just a careless error on my part. Anyway, I am looking forward to listening to this in my system. I am traveling to my old stomping grounds in the San Francisco Bay Area, and some of my audio buddies there have asked me to bring it along for auditions in their respective systems. The nice compact and sturdy chassis will fit well in my luggage.
I’m going to try and make to this year’s BAF in San Francisco too.
I'm not certain if this is the right thread for this but here I go:
Has somebody got a clue when the B1 with the nutube will be available again on the diyaudiostore? I'm asking because I missed the opportunity to buy one there and now I'm trying to get my hands on one in the Swap Meet Forum. Also if anyone has a B1 she or he wants to sell or the kit for it than please pm me or reply to my entry in the Swap Meet forum.
Has somebody got a clue when the B1 with the nutube will be available again on the diyaudiostore? I'm asking because I missed the opportunity to buy one there and now I'm trying to get my hands on one in the Swap Meet Forum. Also if anyone has a B1 she or he wants to sell or the kit for it than please pm me or reply to my entry in the Swap Meet forum.