Tube audio-phoolery -- more teats on bulls

jackinnj · 10th February 2012, 11:55 PM

Sterophile reviews the Z-Infinity "Z40" -- and there's a pair of 12AU7's with the only connection to the heaters.

kevinkr · 11th February 2012, 12:08 AM

I'm still waiting for my copy of Stereophile to arrive.. I'm a little surprised that they would review something like this..

aardvarkash10 · 11th February 2012, 12:17 AM

they are produced at one a minute apparently

SY · 11th February 2012, 12:26 AM

Does it work by ethereal radiation from the tubes? This is an exciting new world of physics.

smoking-amp · 11th February 2012, 12:45 AM

I seem to recall someone posting here once about how they improved the sound after they connected a wire from their amp to just one tube pin. With the heaters lit up here, they must have at least two pins connected in the Z40.

jackinnj · 11th February 2012, 01:23 AM

Quote:

Originally Posted by kevinkr

.. I'm a little surprised that they would review something like this..

Atkinson is the "honest broker" -- like Diogenes carrying a lamp in the daylight, but more subtley if you read the measurements portion of the reviews.

riccoryder · 02:22 AM

They might as well add a couple of 6BK4Bs or 3A3's with the numbers rubbed off while they're at it. I guess they don't glow enough or look like audio tubes. Get rid of some odd 5 Volt tubes?

kevinkr · 11th February 2012, 01:40 PM

Actually I read the article this morning and I guess this is the so called grape vine effect. The assertions made in this thread are at best inaccurate. The amplifier has 4 EL34, two 12AU7 and two 12AX7. Except for the filaments the 12AX7 are not connected, Art Dudley comments pretty forthrightly about this and dug far enough to determine that the reason is that the manufacturer uses a standard chassis and had two holes to fill. (Why the manufacturer did not cap the unused holes is a mystery IMHO.)

Jack didn't quite get the story straight.. This is a tube amplifier and has an all tube signal path. Looks quite nice too.

dirkwright · 11th February 2012, 01:45 PM

Quote:

Originally Posted by jackinnj

Atkinson is the "honest broker" -- like Diogenes carrying a lamp in the daylight, but more subtley if you read the measurements portion of the reviews.

I'm surprised that he can hear anything above 5kHz. How old is he now?

doozerdave · 11th February 2012, 01:50 PM

I can see them leaving the tubes with anode and cathode resistors to draw a quiescent current so they don't have to change their HT dropping resistors for mass production, but I can't image that two tubes (with sockets!) and four resistors would be cheaper than stocking a slightly larger value dropping resistor... who knows. Maybe blank plugs are expensive.

10th February 2012, 11:55 PM	#1
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	Tube audio-phoolery -- more teats on bulls Sterophile reviews the Z-Infinity "Z40" -- and there's a pair of 12AU7's with the only connection to the heaters.

11th February 2012, 12:08 AM	#2
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	I'm still waiting for my copy of Stereophile to arrive.. I'm a little surprised that they would review something like this.. __________________ www.kta-hifi.net

11th February 2012, 12:17 AM	#3
aardvarkash10 diyAudio Member Join Date: Mar 2007 Location: Auckland, NZ	they are produced at one a minute apparently __________________ Yes, conservatism thrives on low intelligence and poor information. But the liberals in politics... continue to back off, yielding to the supremacy of the stupid. It's turkeys all the way down. - George Monbiot, guardian.co.uk, 6 Feb 2012

11th February 2012, 12:26 AM	#4
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	Does it work by ethereal radiation from the tubes? This is an exciting new world of physics. __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

11th February 2012, 12:45 AM	#5
smoking-amp diyAudio Member Join Date: Dec 2001 Location: Hickory, NC	I seem to recall someone posting here once about how they improved the sound after they connected a wire from their amp to just one tube pin. With the heaters lit up here, they must have at least two pins connected in the Z40. __________________ Ohms Law V = I R

11th February 2012, 02:16 AM	#7
riccoryder diyAudio Member Join Date: Dec 2011	They might as well add a couple of 6BK4Bs or 3A3's with the numbers rubbed off while they're at it. I guess they don't glow enough or look like audio tubes. Get rid of some odd 5 Volt tubes? Last edited by riccoryder; 11th February 2012 at 02:22 AM.

11th February 2012, 01:40 PM	#8
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	Actually I read the article this morning and I guess this is the so called grape vine effect. The assertions made in this thread are at best inaccurate. The amplifier has 4 EL34, two 12AU7 and two 12AX7. Except for the filaments the 12AX7 are not connected, Art Dudley comments pretty forthrightly about this and dug far enough to determine that the reason is that the manufacturer uses a standard chassis and had two holes to fill. (Why the manufacturer did not cap the unused holes is a mystery IMHO.) Jack didn't quite get the story straight.. This is a tube amplifier and has an all tube signal path. Looks quite nice too. __________________ www.kta-hifi.net

11th February 2012, 01:50 PM	#10
doozerdave diyAudio Member Join Date: Feb 2012 Location: Kitchener, Ontario	I can see them leaving the tubes with anode and cathode resistors to draw a quiescent current so they don't have to change their HT dropping resistors for mass production, but I can't image that two tubes (with sockets!) and four resistors would be cheaper than stocking a slightly larger value dropping resistor... who knows. Maybe blank plugs are expensive.

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