Member
Joined 2012
Here is some info on the differences between 12AX7 tubes from different manufactures.
http://www.amplifiedparts.com/tech_corner/12ax7_comparison_of_current_made_tubes
http://www.worldtubecompany.com/mm5/merchant.mvc?Screen=TF-2
My own selection criteria would include a good price from a trustworthy supplier.
http://www.amplifiedparts.com/tech_corner/12ax7_comparison_of_current_made_tubes
http://www.worldtubecompany.com/mm5/merchant.mvc?Screen=TF-2
My own selection criteria would include a good price from a trustworthy supplier.
Last edited:
Most of those are such features that the manufacturers do not even specify/present to users.
For me it is diffucult to think what I could benefit for such information.
Typical published specifications are more than sufficient.
The construction of the 12AX7 variant probably has more effect on performance than anything else. My own test have shown that long plate types have measurably lower distortion than other types. If you plan to use ac heaters then a spiral wound filament can be an advantage. My preferred version is the 12AX7LPS.
Cheers
Ian
Cheers
Ian
SY likes the JJ as an economical and good performer. (I do too, but think they are somewhat short lived from direct personal experience) I think at a certain point this discussion becomes academic, there is nothing like direct experience as opposed to hearsay and opinion. Just go out and buy some, look for bargains at radio shows, antique shows, flea markets, ham fests and online.
Grab:
7025
6681
5751 (near equivalent)
E83CC
ECC83
12AX7
12AX7A
12AX7WA
Shop carefully and at least some can be had for little money. Buy reasonably priced modern production as well as anything vintage that catches your eye.
My best recent score was a quartet of early 1960s vintage Telefunken EL84 and three Telefunken smooth plate ECC83 pulled from an abandoned stereo console down the street from my house. All tested as new.. FREE!
Grab:
7025
6681
5751 (near equivalent)
E83CC
ECC83
12AX7
12AX7A
12AX7WA
Shop carefully and at least some can be had for little money. Buy reasonably priced modern production as well as anything vintage that catches your eye.
My best recent score was a quartet of early 1960s vintage Telefunken EL84 and three Telefunken smooth plate ECC83 pulled from an abandoned stereo console down the street from my house. All tested as new.. FREE!
Because the company is run by shady persons. And because they need to keep up sales or they go out of business.
Remember an EL34 would have cost something like 100 modern euros back in the 60s
Anyway watering of type designations is not something new.
For instance Tungsgram produced alot of tubes thay had a T before the name E.G. TAL4
V4lve.
Remember an EL34 would have cost something like 100 modern euros back in the 60s
Anyway watering of type designations is not something new.
For instance Tungsgram produced alot of tubes thay had a T before the name E.G. TAL4
V4lve.
...or run by marketing wizards
sad
i think, one part of success recipe is to make tubes on vintage equipment. they have it.
but that´s not whole story.
they should have the balls to develop advanced tube versions, for example like chinese are doing graphite versions of 300b.
how about revival 100,250TL ???
sad
i think, one part of success recipe is to make tubes on vintage equipment. they have it.
but that´s not whole story.
they should have the balls to develop advanced tube versions, for example like chinese are doing graphite versions of 300b.
how about revival 100,250TL ???
Still, they produce pretty darn good tubes, especially the small-signal types. I've had issues (short life, build quality) with their octal types, but IMHO their 7- and 9-pin types are Things of Beauty. I'm especially fond of their 12AX7 with the spiral heater. Letters and designators notwithstanding, these are great tubes at a good price.
Member
Joined 2012
many thanks!
My mean is not going to compare which brand is good or not, I'm just wish to select good tubes from hundreds of tubes. So, my concern is these values must be controlled to what extent?
IP Emission
GM
H-K Leakage
Gas
Noise
Also, I think a good tube requires a good sound quality, also need to have a long life and good price.
My mean is not going to compare which brand is good or not, I'm just wish to select good tubes from hundreds of tubes. So, my concern is these values must be controlled to what extent?
IP Emission
GM
H-K Leakage
Gas
Noise
Also, I think a good tube requires a good sound quality, also need to have a long life and good price.
I wonder what could be the reason that the manufacturers have never mentioned anything about this feature in the tube data ??
Could it be so that this does not exist ?
Or if it exist, is it not controllable by the manufacturers ?
Still it seems to be most important for so many diyers.
Member
Joined 2012
I found a page to introduce how to select 12ax7, unfortunately, which only mentioned the Ip meas and GM, other items not mentioned.
How to select 12AX7
How to select 12AX7
Last edited:
That page is about testing for faulty ones (worn out or badly made). It won't tell you about sound, but no ordinary test will tell you about sound. A good circuit will work well with almost any non-faulty valve - with the exception of noise and microphony. A bad circuit may need valves with a particular type of characteristic - perhaps similar to the ones used when the circuit was 'designed'.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.