Hi, I have the Nutube B1 on order. My set up is Minidsp SHD Studio streamer to Ares dac to Purifi amp.
I intend to put the NuTube B1 between dac and power amp. Because I use volume control of the SHD Studio I want to leave out the volume pot and input selector and just connect the output of the dac straight to input on the B1 pcb. The Ares dac outputs 2.2V max on RCA but is usually set at - 40dB max. Is skipping input selector and volume pot feasible? Or should I take extra measures?
I intend to put the NuTube B1 between dac and power amp. Because I use volume control of the SHD Studio I want to leave out the volume pot and input selector and just connect the output of the dac straight to input on the B1 pcb. The Ares dac outputs 2.2V max on RCA but is usually set at - 40dB max. Is skipping input selector and volume pot feasible? Or should I take extra measures?
I would think you would want a resistor in place of the pot. Just between signal and ground to establish input impedence. If the pot is 50k, then 50k.
That said, I'm not sure why you'd want to add an extra component. Do you need the gain?
That said, I'm not sure why you'd want to add an extra component. Do you need the gain?
Thank you for your answer. I'll add the resistor.
Concerning the additional component I just want to experiment with tube sound added to the very neutral power amp. Could have bought a cheap tube pre but DIY is much more fun. I'm feeling a bit lost after finishing the Purifi amp. Already have an ACA in use in my study. Bigger class A amps are to big for my surroundings [emoji2].
high pitch noise
I'm having an issue with my Korg preamp. When I use it to drive my Acurus A200 amplifier and Zu Omen speakers, I can hear a very high pitch tone (even with no input signal to the preamp), almost at the limit of hearing. If I leave it running, the tone may fade, then return in a few minutes.
When I use my amp camp amp instead, I get no such tone. Also, if I use my Acurus amplifier with another preamp (Lexicon MC-1) I do not get the tone either. Any ideas?
I'm having an issue with my Korg preamp. When I use it to drive my Acurus A200 amplifier and Zu Omen speakers, I can hear a very high pitch tone (even with no input signal to the preamp), almost at the limit of hearing. If I leave it running, the tone may fade, then return in a few minutes.
When I use my amp camp amp instead, I get no such tone. Also, if I use my Acurus amplifier with another preamp (Lexicon MC-1) I do not get the tone either. Any ideas?
It's probably the ringing from the Nutube. My case is the fully sealed (non-pioneer) version and I only really hear ringing briefly when I flip the power switch, but for a time I thought I was hearing ringing when I had my Raspberry Pi / DAC unit resting on top of the B1K. so if you have any high-frequency emitting devices near your B1K, try moving them around.
a good attempt is to put a book on the case to test isolation ;-) Simple and help to trouble shoot (do the same for the bottom plate if you have air gap as well)
to R-K Ronningstaad #6505
Hello R-K Ronningstaad,
a nice B1 KORG NUTUBE-pre!
Enjoy the sound!
Adjust / play with your trimpots and try to listen to it with inverted speakeroutput.
Can be an interesting experience...😉
Cheers
Dirk 😀
Hello R-K Ronningstaad,
a nice B1 KORG NUTUBE-pre!
Enjoy the sound!
Adjust / play with your trimpots and try to listen to it with inverted speakeroutput.
Can be an interesting experience...😉
Cheers
Dirk 😀
Thank you Dirk. I have tried it briefly. Still missing four RCAs. But selector switch and four inputs are finished, so I think I shall insert it now.
B1 Korg max signal voltage
Hello, all. Unfortunately, I haven't been able to found this info so far, so I will ask my question - what is B1 Korg edition maximum signal voltage? I know it's a unity-gain buffer, so if I input 2 volts, I get about the same on the output. But what about high-level sources? Will it clip if I input, say, 17 or 30 volts?
I am planning to build bridged F4 monoblocks to use primarily as current buffers for a low power SET amp, however I wanted to be able to sometimes use F4 XLR inputs as well.
At the same time I was marveling the B1 nutube design, thinking of building a balanced version by utilizing 2 stereo boards.
Some pro dacs have very high signal levels on XLR outs, and I started wondering what is the maximum signal level B1 nutube will be able to handle without clipping.
If it is high enough, I might be able to drive F4 with balanced B1 nutube and a high level source component.
Hello, all. Unfortunately, I haven't been able to found this info so far, so I will ask my question - what is B1 Korg edition maximum signal voltage? I know it's a unity-gain buffer, so if I input 2 volts, I get about the same on the output. But what about high-level sources? Will it clip if I input, say, 17 or 30 volts?
I am planning to build bridged F4 monoblocks to use primarily as current buffers for a low power SET amp, however I wanted to be able to sometimes use F4 XLR inputs as well.
At the same time I was marveling the B1 nutube design, thinking of building a balanced version by utilizing 2 stereo boards.
Some pro dacs have very high signal levels on XLR outs, and I started wondering what is the maximum signal level B1 nutube will be able to handle without clipping.
If it is high enough, I might be able to drive F4 with balanced B1 nutube and a high level source component.
to Vladbath #6512
Hello Vladbath,
Nelson Pass states in his article about the B1 Korg Nutube that the amplification factor is at around 16dB. So this is no unity gain buffer.
https://www.firstwatt.com/pdf/art_diy_nutube_preamp.pdf
The B1 is a unity gain buffer.
https://www.firstwatt.com/pdf/art_b1_man.pdf
Greets
Dirk 😀
Hello Vladbath,
Nelson Pass states in his article about the B1 Korg Nutube that the amplification factor is at around 16dB. So this is no unity gain buffer.
https://www.firstwatt.com/pdf/art_diy_nutube_preamp.pdf
The B1 is a unity gain buffer.
https://www.firstwatt.com/pdf/art_b1_man.pdf
Greets
Dirk 😀
Thanks a lot, Dirk!
My bad) I was looking around here and forgot about the ultimate source)))
Apparently it has gain around 16 and it seems that maximum voltage out is 5 volts. Hardly enough for a bridged F4 to shine in full glory, I gather, but more or less sufficient to drive it to moderate levels. Pete Millet's balanced preamp/hpa seems more apt to drive F4 (12.8 volts rms out), but it seems rather tough to set up for those with lesser engineering skills and knowledge like myself, compared to b1 korg kit.
Best regards
Vlad
My bad) I was looking around here and forgot about the ultimate source)))
Apparently it has gain around 16 and it seems that maximum voltage out is 5 volts. Hardly enough for a bridged F4 to shine in full glory, I gather, but more or less sufficient to drive it to moderate levels. Pete Millet's balanced preamp/hpa seems more apt to drive F4 (12.8 volts rms out), but it seems rather tough to set up for those with lesser engineering skills and knowledge like myself, compared to b1 korg kit.
Best regards
Vlad
The B1 Korg has quite some harmonics, and that level rises with the output voltage, so depending on your taste you may not want it to deliver more than say 2V...
Of course "your mileage may vary"
Claude
Of course "your mileage may vary"
Claude
Hello R-K Ronningstaad,
a nice B1 KORG NUTUBE-pre!
Enjoy the sound!
Adjust / play with your trimpots and try to listen to it with inverted speakeroutput.
Can be an interesting experience...😉
Cheers
Dirk 😀
Lettering of the front remains. Earlier attempts of mine used a transparent with lettering, fixed behind an acrylic front plate. Seems the Lettraset I used in the past is no more available. I am looking for a nice and cheap way of finishing the front panel.
to Vladbath #6514
Hello Vladbath,
to drive your F4 you will need a preamp with a lot of voltage swing.
The Impasse - preamp or BA-3 as a preamp (with higher rail voltage - my one is running on +-30V) could be good candidates. 🙄
Have fun!
Dirk 😀
Hello Vladbath,
to drive your F4 you will need a preamp with a lot of voltage swing.
The Impasse - preamp or BA-3 as a preamp (with higher rail voltage - my one is running on +-30V) could be good candidates. 🙄
Have fun!
Dirk 😀
Thanks, Claude and Dirk.
Some good DHT harmonics is what I seek) I want not absolute precision, but maximus subjective pleasure, that's why I prefer directly heated single ended tubes as preamplifier stage.
At present I use Manley NeoClassic 300B preamplifier, but unfortunately it doesn't have a balanced output and most likely enough rms voltage. I would ultimately prefer a 101D, 4P1L, 2A3 / 6B4G or may be even 845 preamp with good voltage swing. But most such designs need very good output transformers, and those are hard to find and gonna cost A LOT (good Tango/Tamura, silver Magnequest, or custom wound nickel/permalloy core trafo).
Korg nutube is essentially a DHT, and in B1 you can even let the user tune the harmonics. I wish there was a version of it with high gain and big voltage output, like 30v rms, or that someone smart would design an add-on 101D or 2A3 capacitor coupled preamp output stage for b1, with selectable gain. That would make an ultimate killer preamp, all-DHT, universal and suitable even for low or no gain power amps. Dreams, dreams...
Some good DHT harmonics is what I seek) I want not absolute precision, but maximus subjective pleasure, that's why I prefer directly heated single ended tubes as preamplifier stage.
At present I use Manley NeoClassic 300B preamplifier, but unfortunately it doesn't have a balanced output and most likely enough rms voltage. I would ultimately prefer a 101D, 4P1L, 2A3 / 6B4G or may be even 845 preamp with good voltage swing. But most such designs need very good output transformers, and those are hard to find and gonna cost A LOT (good Tango/Tamura, silver Magnequest, or custom wound nickel/permalloy core trafo).
Korg nutube is essentially a DHT, and in B1 you can even let the user tune the harmonics. I wish there was a version of it with high gain and big voltage output, like 30v rms, or that someone smart would design an add-on 101D or 2A3 capacitor coupled preamp output stage for b1, with selectable gain. That would make an ultimate killer preamp, all-DHT, universal and suitable even for low or no gain power amps. Dreams, dreams...
to R-K Ronningstad #6519
Hello R-K Ronningstad,
nice B1 Korg Nutube! 😉
First impressions? - How do you like the sound?
Greets
Dirk
Hello R-K Ronningstad,
nice B1 Korg Nutube! 😉
First impressions? - How do you like the sound?
Greets
Dirk
Full and nice, relaxed, but not too much so. (And I inverted the polarity of my loudspeakers.
My Korg has the standard electrolytics as DC blocking. No polypropylene, not even in parallel. (That might change later on.)
My Korg has the standard electrolytics as DC blocking. No polypropylene, not even in parallel. (That might change later on.)