RUBY TUBES Codes

[opacheco]

Hi,

If the PC codes stand for PLATE CURRENT under RUBY special test conditions, What is the test conditions used for RUBY TUBES for this code?....Plate Voltage, Idle Plate Current...etc.

What Relation have this PC Code with your setting BIAS CURRENT used for your Amp?, Do they need to be the same in order to get the same performer figures in your amp?

Thanks in advance for any comment.
Opacheco.

[km6xz]

The PC is not a calibrated metric, it is all relative but is useful for determining relative plate current compared to other tubes of the same type. Matching is not as critical in guitar amp as tube companies want you to believe so customers will be wiling to pay for matching.
The test jig, if I remember right after working on it 12 years ago, was 250volts on the anode.

[Enzo]

The matching numbers have absolutely nothing to do with setting the bias on your amp.


What test conditions? Who knows? Whatever their test station presents to the tube. I don't think Ruby is going to tell us. For that matter, think about a tube tester you might have. You set it up like the chart says, then do you know what the plate voltage is and the tube current? I don't know those things on my tube tester. The point of the matching numbers is not to provide practical information to the user. The test conditions are the same for each tube, so the inference is that whatever these conditions are, tubes with similar number results will tend to operate the same as each other elsewhere, and so are "matched."

[tedmich]

Ruby just tests for "uniformly and reproducibly mediocre" IME. Opening up specs is the easiest way to decrease rejection rates in manufacturing, much easier than all that expensive quality system implementation which never ends...business abhors a Hegelian dialectic, but loves an arbitrary vector with positive slope.

[Jazz P Bass]

Had to look that one up!

Hegelian dialectic


noun
an interpretive method, originally used to relate specific entities or events to the absolute idea, in which some assertible proposition (thesis) is necessarily opposed by an equally assertible and apparently contradictory proposition (antithesis) the mutual contradiction being reconciled on a higher level of truth by a third proposition.

[tedmich]

my main gist was modern QSR quality practice call for continuous improvement, there is no conclusion (like a Hegelian dialectic!) while businesses types want to "cut to the chase" see "the bottom line" etc and relax with their maximized profit. No one ever got a bonus by tightening up specs unless the customers were screaming for it, think of all the $ GM saved by putting out crap for the last decade. Upper guys retired with golden parachutes before recalls happened...

ever hear of a bonus "clawback" ? No, because they don't exist! Strip and burn, rape and pillage! You don't even need to buy an indulgence on your death bed! Money = absolution in every real sense. Money also = genetic fitness, we're selecting for weaselly mendacious greed heads.
Look at the team owners, not their antiquated hypermale employees, they're the real winners!

[Pedro Vecino]

I often hear that the balance of power tubes is not critical in guitar amps but I wonder what is critical, then. To me it is within certain limits depending on model. A Deluxe Reverb with 7 milliamps difference between tubes with a good/conservative bias adjust not sound good. However a Plexi with british EL34 Mullard may sound great with 10mA difference but if there is the same difference with a pair of JJ EL34 the sound is directly bad.
I have never known an amplifier in which the treatment of a single thing he has become masterly. It is based on many small details and it is very funny how with very small entity steps (some not significant by themselves) can get a significant difference in musicality. I guess the key element is the overlap that certain "defects" have on others and at the style of construction of an onion is necessary to treat each layer.

Matching of large power tubes (6L6, EL34, etc.) should be (Ruby, TAD ...) with 400 volts or above because with standard 200V testers is a waste of time. Working later with a voltage of 450 volts in an amp the measures are transformed unevenly.

[ric]

It seems like everything effects everything, doesn't it Pedro? I am just a hobby builder and I only built 1 amp w/ fixed bias, to get bias vary tremolo. I am no expert, but my thoughts on this would be with bias that adjusts pairs of tubes to have them "matched"(however it is done) would result in a similar bias on each of the pair. With one of the individual bias schemes shown in these threads, each tube being biased individually it would make little difference to have "matched" sets.