Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

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 10th January 2013, 04:44 PM   #11
diyAudio Member
 
Osvaldo de Banfield's Avatar
 
Join Date: Dec 2011
Location: Barrio Garay,Almirante Brown, Buenos Aires, Argentina
Which is the link between audio distortion at high frequency and gate stoppers?
__________________
LW1DSE
  Reply With Quote
Old 10th January 2013, 04:57 PM   #12
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Oscillation... Good practice to isolate gate from external stray inductance and capacitance, more critical with mosfets than fets, but I have had situations with fairly high transconductance fets that oscillated without gate stoppers. May or may not fix the issue at hand..
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 10th January 2013, 05:01 PM   #13
diyAudio Member
 
Osvaldo de Banfield's Avatar
 
Join Date: Dec 2011
Location: Barrio Garay,Almirante Brown, Buenos Aires, Argentina
OK, I agree, but the guy explicit that audio distortion is at high frequencies, I believe that oscillation must affect all audio spectrum.
__________________
LW1DSE
  Reply With Quote
Old 10th January 2013, 07:23 PM   #14
diyAudio Member
 
Malefoda's Avatar
 
Join Date: Jun 2006
Send a message via MSN to Malefoda
Quote:
Originally Posted by kevinkr View Post
Oscillation... Good practice to isolate gate from external stray inductance and capacitance, more critical with mosfets than fets, but I have had situations with fairly high transconductance fets that oscillated without gate stoppers. May or may not fix the issue at hand..
It did fix the issue!
Many thanks, a big hug to ya all

Here is the 100Ω and the tiny 51Ω (it's far smaller than it looks, flash and zoom worsen its appearance, but minimelf and micromelf are a soldering challenge!), and now all flows smooth and dynamic!
Attached Images
File Type: jpg Pacific.jpg (244.7 KB, 279 views)
__________________
QED T260, Thorens TD-318, Marantz CD-43, TK2050, JBL 4313B & MJK's OB: music!
  Reply With Quote
Old 11th January 2013, 03:26 AM   #15
diyAudio Member
 
The Space Egg Corp's Avatar
 
Join Date: Sep 2010
Location: London & Miami
Blog Entries: 13
BOO YAH !
  Reply With Quote
Old 11th January 2013, 03:55 AM   #16
diyAudio Member
 
The Space Egg Corp's Avatar
 
Join Date: Sep 2010
Location: London & Miami
Blog Entries: 13
BOO YAH !
  Reply With Quote
Old 15th January 2013, 07:28 PM   #17
diyAudio Member
 
Malefoda's Avatar
 
Join Date: Jun 2006
Send a message via MSN to Malefoda
In fact I'm not sure it means " great " but if it's the case: sadly not :'(
Overall volume is louder on left channel. I've cleaned the mess, solder flux, tracks, close matched the 30n with 2x15, it's almost perfect to the eye. But no use...
Before I go any further I need to say that I find weird that with only the right IC connected to the turntable I get no sound on left (!) and a very slight level of music on right, then left only connected, no sound on right but a terrific loud bassy mess on left... wtf!
May that be some loop at work here? My IC are all connected both wires both sides.

So the question is, if there is nothing odd there, how can I fine adjust gain? That's lying on no solid tests but it sounds like a +2/3dB on left most felt at kHz... (I've said it's " vue de nez" (translate by "seen-by-the-nose") but that's the best I can tell about what I hear, not TT related as inverting left/right does nothing for this).
I'm glad I did not started a bigger project! That's so annoying...

But I still have to go, time to shift to side B
__________________
QED T260, Thorens TD-318, Marantz CD-43, TK2050, JBL 4313B & MJK's OB: music!

Last edited by Malefoda; 15th January 2013 at 07:57 PM.
  Reply With Quote
Old 15th January 2013, 07:42 PM   #18
diyAudio Member
 
merlin el mago's Avatar
 
Join Date: Sep 2009
Location: Catalonia new Europe state
Check the signal with the scope, comparing both channels. Can be a cold joint.
  Reply With Quote
Old 15th January 2013, 07:57 PM   #19
diyAudio Member
 
Malefoda's Avatar
 
Join Date: Jun 2006
Send a message via MSN to Malefoda
Hello Catalonian man
I may be able to check with scope but I don't know when sadly :'(
Solder is still warm, a cold joint is unlikely to me, few parts but I'll take a look when I'll manage to scope output signal.
__________________
QED T260, Thorens TD-318, Marantz CD-43, TK2050, JBL 4313B & MJK's OB: music!
  Reply With Quote
Old 16th January 2013, 04:36 PM   #20
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Check the tone arm wiring, and does the problem swap to the other channel when you swap the left and right inputs?

Left and right inputs both return to ground somewhere on your nicely built boards? (No opens)

Measure dc voltages on fet drains and make sure channel to channel that they match to say within 5 - 10%, if they do not, try to match some fets as variations in transconductance, pinch off voltage, etc. may effect the channel to channel gain match. I would not expect the differences to be that large unless the fets were grossly different.

Even better would be to measure the signal levels directly in each stage, verifying that levels match after the first stage, after the passive eq, and finally the second stage.

Post a reasonably sized picture of each side of the PCB and let us have a look, perhaps something different between the two channels will stand out.

Finally have someone else take a look at your handiwork.
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Red board add-on phono/RIAA pre-amp rsumperl Tubes / Valves 5 14th May 2011 04:40 PM
How Can I connect A Balanced RIAA Phono Pre-Amp to a Phono Plug amp input jmartinbaugh Analogue Source 3 25th April 2011 01:24 PM
Pacific Riaa codge Analogue Source 5 4th November 2010 11:53 AM
phono pre RIAA 2001 oldeurope Tubes / Valves 5 8th May 2008 09:05 AM
how build usb phono pre riaa tekton364 Analogue Source 2 28th September 2007 08:50 PM


New To Site? Need Help?

All times are GMT. The time now is 10:14 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2