[Mark D]

Hello all,
Surfing "The Tube Store" site for the possibility of purchasing new
tubes for my CAL Alpha DAC, I click on the EI12AX7 Tube, and this site
claims that this particular 12AX7 Tube is not recommended to be used in
any CAL Audio Gear?

Can any of you gurus here give an explanation as to why this would be? I
have heard the EI12AX7 is a good Tube, but have no idea why it would not
be compatible? Thanks all, Mark

[Phil Allison]

"Mark D"

Surfing "The Tube Store" site for the possibility of purchasing new
tubes for my CAL Alpha DAC, I click on the EI12AX7 Tube, and this site
claims that this particular 12AX7 Tube is not recommended to be used in
any CAL Audio Gear?


** That is NOT what the site actually says !

QUOTE:

" Note to Audiophiles: these tubes cannot be used with California Audio Labs
products"

http://www.thetubestore.com/12ax7.html


Can any of you gurus here give an explanation as to why this would be?


** You really need to ask them.

Does the CAL use metal bases and covers on the tubes?

If so, some 12AX7s may simply not fit.

Eg, most 'X7s are 22mm in diameter while some are only 20mm.




....... Phil

[Mark D]

Hello Phil/Bret/All,
I'm sorry that I didn't exactly quote the site, but yes, you are
correct, that's exactly what it says, and this is what I don't
understand by them saying that these Tubes cannot be used with CAL Audio
Products, which the Alpha DAC is.
(i've even googled-searched other Audio sites, and found evidence of
other Alpha users using EI Tubes.

No, there is no physical interference-obstructions that would not permit
any 12AX7 Tube that I've ever seen from fitting inside (Unless somebody
makes a 12AX7 that's as tall as an EL34?)

I assume the Tube Sockets on the CAL Alpha are Ceramic, sitting raised
above the Board, with no Shrouds, Covers, or obstacles of any kind. I
would also assume that basically all 12AX7 Tubes have to have fairly
close spec tolerances for gain, voltage, etc.

Yes, I did email them, and I'd like to find out thier reasoning behind
thier caution.
As soon as I can get some info about this, I will post it here. Thank
you, Mark

[Mark D]

Hello again all.
This morning I had gotten a reply from Jon at The Tube Store, and his
reply stated that it has been his experience that CAL users trying the
EI12AX7 has had very short lives in thier CAL CAL gear, lasting about 10
hours before failure.

So, I'd assume that there must be some technical explanation, and reason
why these Tubes would not last in CAL gear, but work fine in other
applications?

In my own experience, a recent pair of Shuguang 12AX7 C(9 production
tubes I installed not long ago in my Alpha sounded good initially, but
sounded distorted, and raw after about 15 hours worth of play. Mark

[Phil Allison]

"Mark D"
Hello again all.
This morning I had gotten a reply from Jon at The Tube Store, and his
reply stated that it has been his experience that CAL users trying the
EI12AX7 has had very short lives in thier CAL CAL gear, lasting about 10
hours before failure.


** Failure to what ???????

Failure to please some tube ****** ?

All sounds like total ******** to me.

Buy one, find out for yourself.




...... Phil

[Sander deWaal]

(Mark D) said:

Hello again all.
This morning I had gotten a reply from Jon at The Tube Store, and his
reply stated that it has been his experience that CAL users trying the
EI12AX7 has had very short lives in thier CAL CAL gear, lasting about 10
hours before failure.

So, I'd assume that there must be some technical explanation, and reason
why these Tubes would not last in CAL gear, but work fine in other
applications?

In my own experience, a recent pair of Shuguang 12AX7 C(9 production
tubes I installed not long ago in my Alpha sounded good initially, but
sounded distorted, and raw after about 15 hours worth of play. Mark


Probably a SRPP circuit, and too much voltage difference between the
upper cathode and heater.

Check whether the heater circuit is elevated to a certain DC voltage
by means of a voltage divider with cap bypass from the B+.
Usually some 70 to 100V is used.

--

- Maggies are an addiction for life. -