Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Pass Labs This forum is dedicated to Pass Labs discussion.

B1 with Korg Triode
B1 with Korg Triode
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 8th May 2019, 04:47 PM   #2301
avdesignguru is offline avdesignguru  United States
diyAudio Member
 
avdesignguru's Avatar
 
Join Date: Aug 2016
Location: Tucson, AZ
Default correction previous post

Quote:
Originally Posted by avdesignguru View Post
Enochrome:
I have built both the Nutube Buffer and the Nuhybrid headphone amp with the recommended 1K base stopper resistors ...
Correction:
I only added gate stoppers to the Nutube Buffer since it has Mosfet inputs. My headphone circuit is running the stock bipolars without base stoppers and no oscillation.

The bipolar inputs still have the recommended 100nF Wima film caps. I suppose this value can be so low due to the very high input impedance of the bipolar base.

On the Mosfets, I upped the caps from the 100 nF to 10 ufd electrolytics since that seemed prudent for full frequency response with the newly added 1K gate stoppers.
__________________
Builds: Papa's B1, B1-Korg, F6, M2x, ACN; Wayne C's Whammy, Pearl II; Mark J's T2; Mike R's MoFo; Pete M's NuTube Buffer, NuHybrid, NuClassD; John B's Aikido;
  Reply With Quote
Old 8th May 2019, 07:30 PM   #2302
Marra is offline Marra  United Kingdom
diyAudio Member
 
Join Date: Nov 2009
Location: Near Lincoln
B1 with Korg Triode
Quote:
Originally Posted by Zen Mod View Post
clarify - what jumper , what resistor?
R1 on the circuit board for use when using J113 or a jumper when using K170. I was unsure whether a resistor was needed depending on the idss.
  Reply With Quote
Old 8th May 2019, 08:51 PM   #2303
Nelson Pass is offline Nelson Pass  United States
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
B1 with Korg Triode
Yes. The value depends on the Idss of Q1 and Q2. Ideally we want the current
through Q1 to be about 10% or so less than its Idss in the range from about 6 to
9 mA. The Idss of Q2 and R1 are used to set the current of Q2 to that figure.
  Reply With Quote
Old 9th May 2019, 07:42 AM   #2304
Marra is offline Marra  United Kingdom
diyAudio Member
 
Join Date: Nov 2009
Location: Near Lincoln
B1 with Korg Triode
Thank you Nelson.
  Reply With Quote
Old 9th May 2019, 01:59 PM   #2305
Eric is offline Eric  United States
diyAudio Member
 
Eric's Avatar
 
Join Date: Nov 2000
Location: Central PA, USA
B1 with Korg Triode
I have a silly question and I think I'm missing something obvious, but can't figure out what it is. I was playing around with the PCB mounting technique for my Korg (x-mas version) and found an interesting behavior:

With the PCB screwed tightly to metal standoffs that are mounted to the chassis, everything works/sounds great! Then I lifted the PCB and isolated it from the metal standoffs with neoprene washers on top and bottom of the pcb to provide some vibration isolation. This made one channel buzz (wide spectrum white noise). The buzz is hard to hear with the input pot minimized and increases as the 51k volume control approaches max. Upon power up, the buzzing channel lights up more slowly than the quiet channel and at power down, the buzzing channel stays lit longer than the other one. Removing the washers makes everything behave well again.

So this is clearly a grounding issue: the obvious difference is that the chassis is not grounded when I use the neoprene washers, but given that the PCB mounting holes run the perimeter of the board and connect to the RCA jacks either way, what is the difference? Why the visible difference with the NuTube glow?
__________________
DIY Theater, Aleph-X Amps, LDR based BA-3 pre, B1 Korg, Pearl II, modified SL-1200 TT, F4, M2, Aleph-J, MoFo, a40, ACAs, FHXL & TB 1772 speakers
  Reply With Quote
Old 9th May 2019, 04:26 PM   #2306
cjfrbw is offline cjfrbw  United States
diyAudio Member
 
Join Date: Mar 2007
Location: SF East Bay
You're torquing the board differently and opening up less pristine solder joints?

I managed to catch up with my solder crimes, but one of the symptoms on the 10K variable pots was dimming of the channel on the NuTube. Touched up solder and it was fine.
  Reply With Quote
Old 9th May 2019, 04:37 PM   #2307
avdesignguru is offline avdesignguru  United States
diyAudio Member
 
avdesignguru's Avatar
 
Join Date: Aug 2016
Location: Tucson, AZ
Quote:
Originally Posted by Eric View Post
So this is clearly a grounding issue: the obvious difference is that the chassis is not grounded when I use the neoprene washers, but given that the PCB mounting holes run the perimeter of the board and connect to the RCA jacks either way, what is the difference? Why the visible difference with the NuTube glow?
Check your power supply jack and wiring. Metal bushing types often have 3 terminals. Typically, a center pin plus, an isolated finger that connects directly to the plug barrel minus and a third that becomes disconnected from the finger terminal when the plug is inserted. However, the power supply barrel still touches the jack bushing, making connection to the bushing only.

If your PCB supply minus is connected to the switched terminal instead of the finger, then the chassis becomes the only way the power supply minus connects to the circuit.
__________________
Builds: Papa's B1, B1-Korg, F6, M2x, ACN; Wayne C's Whammy, Pearl II; Mark J's T2; Mike R's MoFo; Pete M's NuTube Buffer, NuHybrid, NuClassD; John B's Aikido;
  Reply With Quote
Old 9th May 2019, 05:06 PM   #2308
Eric is offline Eric  United States
diyAudio Member
 
Eric's Avatar
 
Join Date: Nov 2000
Location: Central PA, USA
B1 with Korg Triode
I will double check both. Thanks, guys!
__________________
DIY Theater, Aleph-X Amps, LDR based BA-3 pre, B1 Korg, Pearl II, modified SL-1200 TT, F4, M2, Aleph-J, MoFo, a40, ACAs, FHXL & TB 1772 speakers
  Reply With Quote
Old 9th May 2019, 05:56 PM   #2309
Nelson Pass is offline Nelson Pass  United States
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
B1 with Korg Triode
Remember that the plate of the tube is a high impedance spot, and is happy to
pick up on unshielded noise. If the chassis is not grounded, it becomes part
of the problem.
  Reply With Quote
Old 9th May 2019, 06:15 PM   #2310
Eric is offline Eric  United States
diyAudio Member
 
Eric's Avatar
 
Join Date: Nov 2000
Location: Central PA, USA
B1 with Korg Triode
Ah - I was considering the chassis to be "a shield" (not grounded) rather than "a shield with a drain" (grounded). I'll retry the washers and add a ground wire.
__________________
DIY Theater, Aleph-X Amps, LDR based BA-3 pre, B1 Korg, Pearl II, modified SL-1200 TT, F4, M2, Aleph-J, MoFo, a40, ACAs, FHXL & TB 1772 speakers
  Reply With Quote

Reply


B1 with Korg TriodeHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Korg NuTube is now available online pmillett Vendor's Bazaar 155 5th September 2019 03:19 PM
New tube tech from Korg Newk_Yuler Tubes / Valves 38 15th January 2017 02:55 AM
2 X PIONEER CDJ-1000 MK3 PLAYER, Korg M3 88-Key Workstation / Sampler,Yamaha Korg holocoast Vendor's Bazaar 0 22nd August 2009 08:03 AM
tapping into keyboard of Korg Polysix mashaffer Instruments and Amps 0 5th October 2008 02:06 AM
Just ordered a Korg EMX-1 MikeHunt79 Tubes / Valves 5 19th May 2008 09:34 PM


New To Site? Need Help?

All times are GMT. The time now is 05:11 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki