help on id of tubes - 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 13th March 2006, 10:38 PM   #1
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
Default help on id of tubes

Hi all,

I recently bought an audio innovations 300 amp:

http://www.drtube.com/img/icon-gif.gif

The amp is push-pull 10W with phono stage thats switchable between MM and MC.

7 tubes in this thing, 4 ECL86, 2 ecc83 (12AX7) plus one other that has absolutely no markings on it. It looks like a 12AX7, but the internal structure at the bottom of the tube looks a bit different to the other 2 12AX7s .... could this just be maunfacturing differences? The tube is the same size and shape as the 12AX7 with the same number of pins.

Theres so little about this amp out there, that I though I might ask here first about the mystery tube!

Many thanks in advacne for any help that anyone can give,
Fran
  Reply With Quote
Old 13th March 2006, 10:54 PM   #2
EC8010 is offline EC8010  United Kingdom
diyAudio Moderator Emeritus
 
EC8010's Avatar
 
Join Date: Jan 2003
Location: Near London. UK
Perhaps if your link worked, it would be possible to comment...
__________________
The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
  Reply With Quote
Old 14th March 2006, 01:12 AM   #3
diyAudio Member
 
Join Date: Feb 2006
Location: East central MN
The 6EU7 is basically a 12AX7 with a different pinout. Do pins 1 and 2 look like they are for the heater?

Is this the schematic you were trying to link to?

http://www.drtube.com/schematics/ai/ai300mk2.gif
  Reply With Quote
Old 14th March 2006, 11:09 AM   #4
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
Hi,

yes. thats the schematic... sorry for the link not working in the post above..

How would I check if pins 1 and 2 are for the heater? (I'm only new at this!)


Fran
  Reply With Quote
Old 14th March 2006, 03:31 PM   #5
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
Hi all again!


OK, I've thought about this for a bit longer and have wondered about coming at it from the other side. If i pulled the unmarked tube from the socket, what tests can I do to tell what it is? Can I measure resistances and so on across certain pins?


Fran
  Reply With Quote
Old 14th March 2006, 03:44 PM   #6
EC8010 is offline EC8010  United Kingdom
diyAudio Moderator Emeritus
 
EC8010's Avatar
 
Join Date: Jan 2003
Location: Near London. UK
Quote:
Originally posted by woodturner-fran
Can I measure resistances and so on across certain pins?
No. A far better method would be to look into the valve and identify which pins are which. The anode is the big outer structure, the heaters are the white wires coming out of the centre. The cathode is the (often cylindrical) sleeve surrounding the heaters, and the grid surrounds the cathode. When you know the pin-out it becomes easier to trace the circuit around the unknown valve. The component values and working voltage will give a clue as to what the valve is.

Frankly, in an amplifier of that era, it's likely to be an ECC83/12AX7.
__________________
The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
  Reply With Quote
Old 14th March 2006, 04:53 PM   #7
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Is that schematic similar to your model amplifier? If so the type may be an ECC82/12AU7 which from memory was a type audio innovations did use.
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 14th March 2006, 09:05 PM   #8
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
Yep,

as far as I can tell thats the schematic.... However, if you look at the schematic there are 4 ecl 86 - OK, I understand that the schematic shown uses "half" and ecl86 and that only one channel is shown. Then there is the ecc 82 - this is for one channel and there would be another ecc82 for the other (in mine these are the ecc83) - this would be the preamp section. What isn't shown in that schematic is the 7th tube that I have and must really be for the phono stage?

Another clue is that the ecl86 are mullard, which means they were replaced at one time, but the ecc83s are "precisa" - which were the tubes supplied originally in this amp, but the last mystery tube has no label so must have been replaced at one stage.

Will take a few photos and post them here, maybe that would give a better idea.

Can I just say thanks for all your efforts so far!

Fran
  Reply With Quote
Old 14th March 2006, 09:17 PM   #9
diyAudio Member
 
Join Date: Jan 2006
Location: Ireland
Guys,

I just got the info!!!!!!

the tube complement is:

4XECL86 (6GW8)

2xECC83 (12AX7)

1XECC82 (12AU7)


Many many thanks for all your help..... hope the info helps someone else at some stage.


Fran
  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
Tube Noob! need help with tubes lots of tubes therapy_fan Tubes / Valves 15 29th January 2009 09:01 PM
WTT: Various tubes for 6CA4/EZ81 rectifier tubes GordonW Swap Meet 4 27th August 2008 12:37 AM
Tubes! Geek Swap Meet 4 16th May 2008 06:20 PM
CV428 tubes (Loktal 807) tubes FS mobyd Swap Meet 3 2nd January 2008 11:26 AM
many new tubes and tubes meter for sale elviukai Swap Meet 4 30th October 2003 09:22 AM


New To Site? Need Help?

All times are GMT. The time now is 08:13 AM.


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