testing 12AX7 in eico 667 - settings?

[rajuncajun]

Hi, I have searched the forum and not seen a lot on how to best set up an eico 666 or 667 to test 12AX7's. I have a 667 that I just restored and calibrated, and all my 12AX7's test around 20% merit. I'm using the master tube chart from Coletronics. I have some EL84's that are testing over 100%, so I know the eico is working.

For the 12AX7's the charts says that good tubes test above 60%, but I know these tubes are ok since they sound fine in the amplifier.

Should I keep using these settings and assume that 20% or above is a good tube, or are there alternative settings (that won't stress the tube) that I could try?

Here are the settings I'm using now:

12.6 67 35 6661245 161111 1 4 6,7,8 6

then,

12.6 67 35 4511266 661111 1 4 1,2,3 1

 

[rajuncajun]

Found settings on a telecaster guitar posting, now the tubes are testing 60-80%.

Grid set at 7, plate 93, V2, S4. Other settings for levers same as what I listed above.

Here's the link to the thread:

http://www.tdpri.com/forum/amp-central-station/116001-vintage-tube-testers-reliablity.html

 

[Bob E.]

The Coletronics/Eico 666 chart I downloaded from the BAMA site has the following:

12.6 G37 P75 45112 66661 V2 S3 1-2-3 1

then

12.6 G40 P76 66612 45161 V2 S3 6-7-8 6

I'm not sure why they change the grid and plate settings for the second element. Your tester must have a few extra levers...

--Bob

 

[MoparMan]

The Eico 666/667 testers were notorious for having several charts. They had a lot of errors on many of the versions of the charts. I think there was about 6 different chart versions also. Check more out here:

http://www.tone-lizard.com/Eico666.html

 

[robert1]

apparently, by looking at the lever count in the original post, you are using a 667. what happened with the original roll chart that it was supplied with?
i have a 667 right here next to me. the settings are as follows:

Fil=12.6 Grid=40 Plate=76 Levers=6661245 - 161111 V=2 S=3
Fil=12.6 Grid=40 Plate=76 Levers=4511266 - 661111 V=2 S=3

my 667 has the original roll chart that was supplied with it.

 

[rajuncajun]

I have the roll chart, but was weary of using it since I've read that the coletronics supersedes all previous charts, which contain errors. Of course, the coletronics chart contains errors too, but supposedly fewer than other publications. Maybe I should use the roll chart more often.