diyAudio - View Profile: triode_al
Go Back   Home > Forums > Members List
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

triode_al triode_al is offline

diyAudio Member

About Me

  • About triode_al
    Biography
    professor of fluxus
    Location
    Westland
    Interests
    triodemania
    Country
    Netherlands
  • Signature
    SPU --> two stage RIAA; Kaneda pre; 300B SE no feedback; Open Baffle, Lowther

Statistics

Total Posts
Blog
Wiki
  • Wiki Contributions: 0
  • Wiki Comments: 0
  • Recent Wiki Activity: triode_al has no recent wiki activity
General Information
  • Last Activity: 23rd June 2016 09:03 AM
  • Join Date: 30th May 2004

Blog

View triode_al's BlogRecent Entries
Latest Blog Entry

Posted 18th May 2012 at 03:03 PM by triode_al Comments 0
Posted in Uncategorized
I have been reworking my RIAA preamp the past weeks - main effort to install a SALAS shunt in the HV.
I had some problems looking like instability of the DC. I also noted that every on/off cycle, the problem got worse. And while developing, I would switch the preamp on an off often, to see the effect of the tweaks, such as setting the shunt cuirrent.

Later I found that one 6N9S tube was 'dying', really, it went black, but intermittent.
The heater wires probably had been stretched a bit and in cold state they made some contact (measured 3-4 ohm) but when heated up it lost contact. The effect cascaded into the Vb, and was seen on both outputs similarly.

I conclude The [Russian, Reflektor brand, big logo] tube is very sensitive to the heater.

I had the two tubes running in series from a medium impedance 12 V source (IRF250, gate connected to drain via 100k resistor and a 300 uF cap: relatively slow start of 2 secs. But too fast probably...
Hide this!Advertise here!

New To Site? Need Help?

All times are GMT. The time now is 05:09 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.
Copyright 1999-2016 diyAudio

Content Relevant URLs by vBSEO 3.3.2
Wiki