B1 with Korg Triode

Jump to Latest
#4,882
Just for fun, I dug out an old 2x30w hypex class D kit I built some years ago and intended to use as summer amps for my Altec A5s, instead of the 300b SE and Kt88PP valve monoblocks I mainly used before DIYing First Watt amps. There is no buffer in front of the Class D, but I used a small Sowter trafo to convert from single-ended input to balanced. They sounded quite aggressive with my simple autofomer passive pre and did not have enough gain. Yesterday I tried them with the B1 Korg in front and the combination was much better than expected. No aggressiveness, no overly dry bass with the Altecs. All inn all quite good.
The B1 Korg is a wonderful pre.
 
#4,883
After I used Staving Student II as preamp for a while I have now switched back to Korg and I must say it is very nice sounding. Combination: Korg + M2X (Norwood) + OBL-15 is very nice. I remembered to swap speaker outputs at M2X to get correct phase (and 2nd harmonic negative phase).

The setup if perfect for "real" music like acoustic music, live music, classical.
It is not that good for electronic music and music that has got a lot of "makeup" to enhance bass response etc. But that is not my kind of music anyway.
 
#4,886
Just finished my B1 Korg Triode!

Sound is great, fed from my Allo Katana DAC (powered by Salas UBiB shunt regs), through my Salas Mesmerize DCB1 as input selector/buffer, and the B1 Korg serving as input buffer for my F6.
 

Attachments

  • 2020-06-11-DSCF6429.jpg
    2020-06-11-DSCF6429.jpg
    366.8 KB · Views: 804
#4,888
ahtllc said:
OK, I could use some help.


I built the full kit about 3 months ago, but have been having problems with it ever since. I've been double checking polarities and values ever since.


I get the correct in-spec voltages for T1-T6. When it is first powered on, I also can adjust T7,T8 to around 10 volts. I let it sit to warm up, but after a minute or so, T8 starts dropping, eventually going down to about 3 volts. I've left it on for 24 hours, and it still stayed at 3 volts. Also, it's side of the NuTube doesn't have that nice blue glow.


I used to have this problem with both T7 and T8, but now it seems to be confined to T8.


I've put an oscilloscope probe on T8 and noticed it is quite noisy and unstable.


Does anyone have any ideas on what to check next?
Click to expand...


I think I solved the problem. I removed the NuTube, removed the solder and cleaned the board, and then reinstalled the NuTube, this time soldering it in from the opposite side of the PCB. The PCB pads on the bottom of the board may have been contaminated initially or just weak and not making a good connection, even with my Metcal solder station.


If anyone else is seeing their T7,T8 voltages drift downward, they might give this a try.
 
#4,891
kbergsson said:
Just for fun, I dug out an old 2x30w hypex class D kit I built some years ago and intended to use as summer amps for my Altec A5s, instead of the 300b SE and Kt88PP valve monoblocks I mainly used before DIYing First Watt amps. There is no buffer in front of the Class D, but I used a small Sowter trafo to convert from single-ended input to balanced. They sounded quite aggressive with my simple autofomer passive pre and did not have enough gain. Yesterday I tried them with the B1 Korg in front and the combination was much better than expected. No aggressiveness, no overly dry bass with the Altecs. All inn all quite good.
The B1 Korg is a wonderful pre.
Click to expand...

I also use Hypex with H2 (not KORG) with JBL 15" woofers. I think low frequency control of Hypex is too lean/tight for 15", and adding H2 makes them sing a little better. 🙂
 
#4,894
I've very kindly been offered the Loan of a Third Version of the Build of the
B1 Korg Nutube by an Individual who has produced two other boards and mentored on two builds carried out by friends.
There is a B1 Korg Nutube admiration taking place within my local HiFi Group.
I'm very much looking forward to experiencing this Device in my system as the loan is for the long term and will commence from tomorrow 🙂
 
#4,898
Hey guys a quick question and I guess I read this somewhere on this long thread but unable to find the information.
On the store B1 Korg boards for the jfets, there are 2 positions marked as JQ1/KQ1 for 4 of the Q1 and another 4 for Q2 transistors. I believe the jfets which came with the board in the store kit provided should go into the JQ1/JQ2 positions right and leave the K position open?

Thanks
 
#4,899
manniraj said:
Hey guys a quick question and I guess I read this somewhere on this long thread but unable to find the information.
On the store B1 Korg boards for the jfets, there are 2 positions marked as JQ1/KQ1 for 4 of the Q1 and another 4 for Q2 transistors. I believe the jfets which came with the board in the store kit provided should go into the JQ1/JQ2 positions right and leave the K position open?

Thanks
Click to expand...
Yes
 
You must log in or register to reply here.
Top Bottom