Tube mic preamp problem - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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 4th January 2013, 03:31 AM   #11
gootee is offline gootee  United States
diyAudio Member
 
Join Date: Nov 2006
Location: Indiana
Blog Entries: 1
Are the Instrument inputs the ones that you called "Hi-Z", before?

Can you check to see if you can measure 48V between the center pin and one of the other pins, at each MIC input jack (with no MIC plugged in)?
  Reply With Quote
Old 4th January 2013, 04:41 AM   #12
diyAudio Member
 
Join Date: Apr 2005
Location: Simcoe Ont
Instrument inputs are marked Hi-z on front panel. I will measure 48v right now.
I am confused about where to find 150V.
A tech told be today that it would bew the tubes. First thing I did was swap left to right tube and then swapped in a pair of other tubes.
Where does the mic get its gain?
  Reply With Quote
Old 4th January 2013, 02:20 PM   #13
diyAudio Member
 
Join Date: Apr 2005
Location: Simcoe Ont
The schematic is definately incorrect. I managed to check for 48V. It is good. I left the probes in and switches off 48 Volt phantom. The voltage droppewd slowly as I expect to see with phantom circuit. Mine has only 8 1N4003 in total. I did not find the source of the 150 Volts but I was able to confirm that I have 160Volts at the plate switch.
I am at this point thinking of walking away and selling as is but rethinking that I bought this to learn about it, willing at the time to lose the money to gain experience.
I was wondering if I may feed the mic input with an MP3 player and begin tracing with an earphone or something like that. I do not have a signal tracer and have not done this before but this may be the time to learn patience and focus.
  Reply With Quote
Old 5th January 2013, 01:58 AM   #14
gootee is offline gootee  United States
diyAudio Member
 
Join Date: Nov 2006
Location: Indiana
Blog Entries: 1
Quote:
Originally Posted by argonrepublic View Post
The schematic is definately incorrect. I managed to check for 48V. It is good. I left the probes in and switches off 48 Volt phantom. The voltage droppewd slowly as I expect to see with phantom circuit. Mine has only 8 1N4003 in total. I did not find the source of the 150 Volts but I was able to confirm that I have 160Volts at the plate switch.
I am at this point thinking of walking away and selling as is but rethinking that I bought this to learn about it, willing at the time to lose the money to gain experience.
I was wondering if I may feed the mic input with an MP3 player and begin tracing with an earphone or something like that. I do not have a signal tracer and have not done this before but this may be the time to learn patience and focus.
Yeah, wow, just learning patience and focus could be worth thousands of dollars, in my case.

Regarding tracing with something going into the mic inputs: I am not an expert, actually. So I don't know what the typical mic output amplitude might be. A quick search might find it. But you could just use a speaker with a mic in front of it, too, with the mic plugged into your unit.

(Sorry. Today was a long day, for me.)
  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
How to make mic input transformer 150:50KCT for mic tube preamp??? delipasha Tubes / Valves 9 3rd February 2012 05:54 AM
Noise problem with Mic Preamp..any help appreciated silentblackhat Solid State 11 20th November 2005 02:17 PM
'Tube' preamp bad for measurement mic? also Apex mic question morbo Multi-Way 10 23rd March 2005 10:19 AM
Mic preamp problem kimarin Solid State 1 29th October 2004 09:11 PM
Tube mic preamp kimarin Tubes / Valves 5 23rd October 2004 09:30 AM


New To Site? Need Help?

All times are GMT. The time now is 10:55 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