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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Sat Jan 04, 2014 2:17 pm
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bluesky636 wrote:
...Nobody is arguing about matching tubes. It is the assignment of arbitrary "grades" to tubes that is the issue...


Yeah, that's what I don't understand, why you say "arbitrary" when it is clearly and simply based on Plate current draw at a fixed grid voltage and a fixed Plate voltage, using exactly the same type of method for testing that nearly everyone uses. This is math, something that I thought you appreciated. :?

Yes, Eurotubes grades their tubes exactly the same way (some kind of tube tester, no dart board), they just use more general terms such as "hot", "cool", "blues option", etc, instead of very specific 1 to 10 scale, and as you've pointed out, Eurotubes puts the Plate current numbers on the tubes or box, correct?. Does Eurotubes label somehow make it less arbitrary than others labels? Believe me, I understand brand loyalty, and unreasonably knocking things that you don't like, no biggie. I've explained things as best I can, maybe not well enough. :(

Oh well, some don't like GT, OK, more tubes for me. :D We weren't even discussing GT, just current rating of tubes, derived scientifically and methodically using modern electronic test equipment.

BTW, my previous post was a kind of paraphrase of Dana Carvey from SNL, when he played the old man that talked about "how much better things used to be" when he was young (similar to some responses in this thread :wink: ). :lol: :lol: :lol:

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Sat Jan 04, 2014 3:42 pm
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shimmilou wrote:
bluesky636 wrote:
...Nobody is arguing about matching tubes. It is the assignment of arbitrary "grades" to tubes that is the issue...


Yeah, that's what I don't understand, why you say "arbitrary" when it is clearly and simply based on Plate current draw at a fixed grid voltage and a fixed Plate voltage, using exactly the same type of method for testing that nearly everyone uses. This is math, something that I thought you appreciated. :?

Yes, Eurotubes grades their tubes exactly the same way (some kind of tube tester, no dart board), they just use more general terms such as "hot", "cool", "blues option", etc, instead of very specific 1 to 10 scale, and as you've pointed out, Eurotubes puts the Plate current numbers on the tubes or box, correct?. Does Eurotubes label somehow make it less arbitrary than others labels? Believe me, I understand brand loyalty, and unreasonably knocking things that you don't like, no biggie. I've explained things as best I can, maybe not well enough. :(

Oh well, some don't like GT, OK, more tubes for me. :D We weren't even discussing GT, just current rating of tubes, derived scientifically and methodically using modern electronic test equipment.

BTW, my previous post was a kind of paraphrase of Dana Carvey from SNL, when he played the old man that talked about "how much better things used to be" when he was young (similar to some responses in this thread :wink: ). :lol: :lol: :lol:


First of all, no where in this thread have I "knocked" Groove Tubes. They are simply the most obvious user of a grading system (1 to 10).

Secondly, let's clarify terms. I consider Ip to be a "rating" based on voltage and current measurements. I am not sure what "Grade" really refers to except that different grades break up differently.

Mesa grades their tubes as Red, Yellow, Green, Gray, Blue, and White.

GT uses 1 to 10.

Fender uses Blue, White, and Red.

You keep talking about Ip. Yes, Eurotubes puts the Ip value on their tubes. But what I have not seen in any of the articles we have looked at is a discussion of the relationship of the Ip rating to the tube Grade. If I have overlooked it, please show it to me and I will shut up. If it is not there, then in my opinion the Mesa, GT, and Fender "grades" are arbitrary.

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Sat Jan 04, 2014 8:08 pm
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Ah, I see. Yes, the grade Red (8-10), White (4-7) and Blue (1-3) do not have the Ip numbers on them, but refer to the exact same thing, the amount of current draw at a given fixed grid voltage and given fixed Plate voltage, absolutely nothing arbitrary about it at all. I guess that you could say that GT wants to be cute and have their own system (not that you did), but it is still based on the same system of measuring current draw. Grade = rating = relative current draw, all derived from measurement, simply labeled differently.

Yes, the lower numbers, whether Ip or 1 to 10 or Red, White, Blue, will breakup earlier on the volume range of an amp, and the higher numbers will breakup later, no matter the type of volume pot. The numbers/ratings are for comparison in the same amp. If you amp has linear or audio taper pots, the rating numbers are still relevant, you merely change the pot scale with a linear or audio taper, which simply means that you arrive at a certain power level of the amp at a different point on the pot's rotation. Changing the volume pot taper has zero effect on the amount power that the amp will produce.

You are correct in that the voltages used for the testing done to come up with the ratings of the tubes will rarely be the same as the amp for which the tubes will be used, except maybe in the case of Mesa amp where all of the parameters are known by Mesa beforehand, but it doesn't matter because the numbers are just for comparison. As in the case of the OP wanting cleaner sound with more volume, he simply needs a higher rating/grade/number compared to the rating/grade/number that he has now. It is the same type of thing with using lower gain preamp tubes, the lower the gain, the later the breakup, the cleaner the sound, except that now we are referring to gain instead of current draw. The gain factor of preamp tubes isn't arbitrary either.

After using literally hundreds, perhaps thousands of tubes myself in hundreds of amps over many years, the ratings and their affect on breakup have become remarkably clear. I certainly think that GT, Mesa, Eurotubes, and anyone else that grades/rates tubes have certainly seen many more tubes than me, and we all can't be FOS. :wink:

Now that that is all cleared up, what about that fantastic Colts comeback! :D

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Sat Jan 04, 2014 8:31 pm
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FWIW... In my experience with 6L6GC family of tubes, the 7581A and the KT-66 have the highest headroom, cleanest tone to very loud.

Brown based, gray glass British MOV/GEC KT-66 and GE (Owensboro, KY) pink-tan, orange lettering based 7581A being the best of these sub-types. Both are $$$. But, a good NOS set will nearly outlast the filter caps.


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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Sat Jan 04, 2014 9:54 pm
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shimmilou,

This stupid forum will not let me respond to your last post by quoting it and adding my my response. This has been going on for a couple of days now. I have reported it each time. I'm really getting sick of this.

Ok, one last question.

Where is the chart/table/calculation/what have you that tells me the grade of the tubes with the following Ip ratings?

bluesky636 wrote:
I just looked at my little box of tubes. I have one matched pair of JJ 6L6GCs rated at Ip = 45 mA, one matched pair of JJ 6L6GCs rated at Ip = 60 mA; two unmatched JJ 6V6Ss rated at Ip = 25 mA and 26 mA, a matched pair of JJ 6V6Ss rated at Ip = 28 mA, and a matched pair of EH 6V6GTs rated at Ip = 33 mA.

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Sun Jan 05, 2014 12:27 am
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I know! I have had that problem a few times, and had to split my response into two parts. Maybe it has to do with the length, and only during certain time periods. I'm guessing that they are doing some kind of system maintenance during these times. :?: :x

Although I don't have a chart, I can tell you that an Ip of 25 is low, 40 is in the medium range, and 60 would be in the high range. It all relates to the current draw, so the higher the current draw, the higher the rating/grade.

Just as a rough guesstimate, I would say that the GT grades are roughly; Blue 1 being around a 20 Ip, and the Red 10 being around a 60 Ip. This is just a guess, and their ranges for current might be much tighter than that, but it gives you an idea of how the current relates to the grade. I know that Mesa says that their tubes all fall into the same range as GT 4 to 6, and based on that I would say that this is close to what the tube spec sheets state.

I should also point out, different suppliers Ip numbers won't necessarily jive with other suppliers numbers as they all might use a different testing system, with different voltages. So, there is a learning curve for different suppliers numbers and where those numbers fall into the low, medium or high grades. For example, a JJ rated at 25 from Eurotubes might not necessarily be the same as a JJ rated at 25 from thetubestore, or an EH rated at 25 from another supplier.

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Sun Jan 05, 2014 3:13 am
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shimmilou wrote:
For example, a JJ rated at 25 from Eurotubes might not necessarily be the same as a JJ rated at 25 from thetubestore, or an EH rated at 25 from another supplier.


"Can you say 'arbitrary', boys and girls?"

Sure ya can.

:roll:

Arjay

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Sun Jan 05, 2014 5:21 am
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Yes, each tube supplier that puts numbers on their tubes or boxes must have arbitrarily picked a different type of test equipment, maybe putting a bunch of equipment names in a hat and then having a random stranger on the street draw a choice for them. 8)

More important than saying it, is defining it:

ar·bi·trary
adjective \ˈär-bə-ˌtrer-ē, -ˌtre-rē\

: not planned or chosen for a particular reason : not based on reason or evidence


This definition certainly doesn't fit any modern testing procedures used to derive a current rating or grade for tubes. Pick your supplier, and their particular current/grade/rating, and not one of them uses an arbitrary system, there is reason and evidence, as well as repeatability and consistency for each particular system. :)

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Sun Jan 05, 2014 8:30 am
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I'll stick with buying well matched tubes and biasing them properly to get the sound and performance I want and not worry about some "tube grade". I'm outta here.

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Sun Jan 05, 2014 8:43 am
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Mike,

I guess the issue I have with tube grading is: what is the reason a tube is not passing the nominal current of its design? I would think that if a 6L6GC is passing only "good" 6V6GT values, at a set plate and grid voltage, there is an issue with that tube. Like maybe it should be rejected?

Or is it that some are designed to early 6L6GA or GB standards? And others are true -GC? Because, as far as I know all 6L6GC should be able to have an idle wattage max value around 30 watts (push-pull, AB1) -- within a specified THD and clipping stats. Right?


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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Sun Jan 05, 2014 8:49 am
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Retroverbial wrote:
shimmilou wrote:
For example, a JJ rated at 25 from Eurotubes might not necessarily be the same as a JJ rated at 25 from thetubestore, or an EH rated at 25 from another supplier.


"Can you say 'arbitrary', boys and girls?"

Sure ya can.

:roll:

Arjay


That's exactly correct.

Previously, the claim was that one could put the same grade tube into an amp and have identical performance with no other changes. Now we find that you have to use the same grade tube from the same supplier to get identical performance with no other changes. No consistency or repeatability between suppliers. Sounds like an arbitrary system to me if each supplier defines "grade" to mean something different regardless of how scientific their measurement process is.

Sorry. My answers got out of order. NOW I am outta here.

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Sun Jan 05, 2014 6:21 pm
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BMW2002Ti wrote:
Mike,

I guess the issue I have with tube grading is: what is the reason a tube is not passing the nominal current of its design? I would think that if a 6L6GC is passing only "good" 6V6GT values, at a set plate and grid voltage, there is an issue with that tube. Like maybe it should be rejected?

Or is it that some are designed to early 6L6GA or GB standards? And others are true -GC? Because, as far as I know all 6L6GC should be able to have an idle wattage max value around 30 watts (push-pull, AB1) -- within a specified THD and clipping stats. Right?


Since we don't know what range of parameters, or at what point a tube's operation should be considered "acceptable", and who determines this, I'm not sure how to answer that. But no way a tube in a push-pull amp should idle at its max wattage rating, it should idle at more like 50% to 70% of its max watt rating.

We do know that a RCA 6L6, a Tung Sol 6L6, a JJ 6L6, a Sovtek 6L6.....etc, will all have different sound characteristics, and often have quite different current draws under the same operating conditions in the same amp, so who is the authority on what is the "proper" range for a tube to operate. Do we go with RCA, and reject all others? I don't think so. Ive seen JJ 6L6 tubes rated anywhere from 17 to 43, and heard of tubes well above that, so are they selling the ones that should be rejected, therefore ripping people off with their "arbitrary" rating? Again, I don't think so. I've seen all kinds of different brands of tubes with a wide range of grades/ratings, and none were unacceptable as far as operation, but some were less desirable because of the want for more headroom or earlier breakup.

According to Mesa, their tubes are selected according to only those that operate in a specific current range, and the tubes that don't operate in that range are rejected. This leads me to believe that the tubes in the range that Mesa uses are the ones that operate closer to the "as designed" parameters, depending on who manufactures the tubes, and Mesa only selects certain manufacturers out of the available types at the time. Tubes that fall above or below the range that Mesa uses are apparently perfectly acceptable for use in many other amps, but will have current draw and breakup characteristics that are different, therefore the grading so that we can make an informed decision about the sound that we desire.

Since the claim in "the good old days" is that no one checked their tubes, just threw them in and played, they don't have a clue as to what a good range is for tubes either. I guess that ignorance really is bliss for some, although I'm sure everything wasn't as peachy as some want to portray. :wink:

These guys crack me up, kind of the old cover the ears and keep saying "I'm not listening, lalalalalalala" :lol: :lol: :lol:

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Sun Jan 05, 2014 6:40 pm
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bluesky636 wrote:
...Sounds like an arbitrary system to me if each supplier defines "grade" to mean something different regardless of how scientific their measurement process is...


You missed it again. The process is the same, the numbers mean the same thing (current draw at a specific grid and Plate voltage applied), just that the equipment is different. Grade still means the same thing, current rating. My tube tester gives a different reading than yours, but the process is still the same, just different design in the equipment, so different voltages, and a different level of current displayed. Use the same brand of tube from the same supplier, and the rating will perform the same each time, and with experience you might learn that a tube that is rated at 30 that was tested using one brand of tester will operate the same as another tube rated at 40 that was tested using another brand of tester.

Quite possibly, the Amplitrex tube tester should be considered the standard, and if everyone had one, the numbers would all be the same. :idea:

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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Sun Jan 05, 2014 8:59 pm
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I can't speak for Shimmi but I think what he is trying to say is that each supplier is consistent as far as the ratings within their own usage system . If your amp has for example a set of No6 White Label Groove Tubes and it was biased and running well, then if you replace those tubes with another set of the same No6 White GT's then those tubes will bias up very similar without a trip to the tech. But the systems are proprietary, to make use of that kind of system you are by nature "locked in" to that system, if you change suppliers (or in fact change to a Red or Blue rated tube in that same system) all bets are off, you are moving outside the established "window" and some bench time is called for.

It is a similar concept to say paint colours you get from a paint supplier, for example if you paint your eaves in Taubmans "Heritage Green" and run out of paint you can't just get a can of Dulux "Heritage Green" and expect a match, in fact the colours may be absolutely nothing alike, it's just a name they have given the colour, you need to stick to the same Taubmans "Heritage Green" in their system and the colour will match every time.

That's my take on it anyway, most people don't obsess over this stuff like we do and don't even know what bias is, before the internet many who now do obsess wouldn't have known better. I see it as a dumbed down way of making tube replacement easy for the average Joe with "plug and play" convenience, like changing a light bulb and to encourage him/her to feel security in sticking to a particular product branding and in doing so avoiding bench time.

I bias and check my own amps/tubes so have no need for such "systems".

I haven't read this whole thread but to the OP, have you had the amp biased since the "Blue" tubes we're put in? If you haven't then that may be the issue because the amp would have come with "White" tubes and biased to suit those, you can't swap to a different colour without rebiasing. Did you swap the tubes to Blue and if you did was the biasing checked and adjusted to 70% dissipation at idle, at that time?




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Post subject: Re: Tubes for Hot Rod Deluxe III for max headroom?
Posted: Sun Jan 05, 2014 9:47 pm
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You got it Snowy. :)

For example, if you get a set of JJ from Eurotubes rated with a number of 25, and you like that sound and need another set, get another set from Eurotubes with the same number and you should be good to go, not even needing a bias adjust.

And to take it a step further, you can figure out how to match up the different suppliers grades to get what you need in a different brand. For example, a GT 6L6 S tube rated at 7, might match up with a JJ 6L6 tube from thetubestore rated at 40. I don't know if those numbers are correct, but you get the idea anyway. It's kind of like model numbers for guitars Each company might use different numbers for similar models, but usually based on some system and not just arbitrarily chosen numbers, and those numbers can usually be "decoded".

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