Types of valves: Advice please

ButterFingers

Hi everyone

Can someone please help me?

I have some questions regarding the valves in my Laney Lionheart L5T-112, as well as valves in general:

1. What is the difference between a high grade and a normal valve?
2. I need to order spare valves. The instruction book says I can use either ECC83 or 12AX7 preamp valves. Can they be used together? How do they differ? Which is the better one?

ECC83/12AX7 preamp tube
EL84 power tube

Tamago

Hi sure

Sonically, in terms of hi-fi, the only difference I experienced between a 12AX7 and ECC83 as I recall, was very little, they sounded both the same to me.

I have seen some tubes featuring both part numbers, so as far as I can tell, they are electrically equivalent, and share the same base and pin out.

ECC series was European, whereas the 12AX was American, that is the difference, pretty much like transistors these days where 2N series is American, and the BC series is European.

A high grade valve could be any of the following:

1) Valves with high endurance specs and/or special construction to make them last longer
2) Hand-picked valves with specific characteristics.

To answer your question I'd say hell yes, the sonic difference between a ECC83 triode and a 12AX7 is very little, the difference could come in depending on how the tube reacts in distortion/overdrive. I have never done that, so I cannot comment but electrically I assure you they are almost identical.

AlanRatcliffe

Tamago wrote ECC series was European, whereas the 12AX was American, that is the difference

+1. That's it right there. You also get models like the ECC803S, which was a military grade valve. 7025 is another common name for a 12AX7.

Grading is different depending on who is grading, some grade on a gain range, some on quality of tone or microphonics. Check with the people doing the grading.

The manufacturer makes the most difference to quality and the way the valve sounds. They each have their own tone. One thing that is certain is that the quality of modern valves is nothing like they were in the '50s and '60s, when valves were commonplace in electronics and the biggest buyers were the military, who pushed for very high quality and reliable tubes. We're gradually getting back to those standards (especially with power valves), but we're not there yet.

matta

Alan the 7025 was a low noise/low microphonic 12AX7, the equivalent to the ECC803S, 7025's were also mil spec, at least the original RCA ones were... today most 7025's are just rebranded 12AX7's.

RE grading, just buy your tubes through a reputable source and they can run all kinds of tests from low noise, low mircophonics, to matching pre amp tubes to standard testing, this is an added service, but most charge between $5-$7 to do it and in some applications it may well be worth doing this.

Any reputable source will a least check for the basic to check the tubes work, many of the production valves ship from the factory DOA, which is why it helps to paya few bucks more to buy from a source that tests them before they ship.

As my signature indicates I keep stock of the standards, preamps, phase invertors and output valves, so PM if you have any questions, also there is Mr. Valve in Joburg who may have some NOS lying around if you want to buy old, but beware as some are used, and sold as such, but can be microphonic/noisy.

Cheers

Matt