| Search | Login/Register
   Home » Audio For Dummies ™ » Get, or made up a tube tester, it’s necessary (45 posts, 3 pages)
  Print Thread | 1st Post |  
Page 2 of 3 (45 items) Select Pages:  « 1 2 3 »
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  Hickok Tube Testers: Quick Reference..  Hickok Tube Testers: Quick Reference...  Audio Discussions  Forum     0  16833  08-09-2005
  »  New  How to test 6C33C?..  You might not need it....  Melquiades Amplifier  Forum     7  85525  04-02-2006
  »  New  The 6E5P tube data...  Bartola Valves: 6e5p beam tetrode SPICE model...  Melquiades Amplifier  Forum     44  390150  07-23-2007
01-12-2007 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 21
Post ID: 3484
Reply to: 3483
Doh! Wrong Pinout
The "gold wire" version tetrode runs fine, now that I have it connected properly.  I switched to my better scope, so photos have visible grids.  Everything is now calibrated, too.  Vertical is 12.5mA per div.  Wow, that tube sure does pump out a lot of current.  No wonder you chose it as a driver.



jh
01-12-2007 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,734
Joined on 05-28-2004

Post #: 22
Post ID: 3485
Reply to: 3484
The Milq’s driver on the tracer: the first blood :-)

Jim,

It is miniature tube that can handle 8W on plate!!! Still the most interesting it’s sound as triode. If you look its internals constriction then you will see a pair of huge “plates” and a large space for the “electron cloud”, it kind of in a way freakishly looking intestines. BTW, this tetrode is one of the very few tubes that Russians create themselves, practically all other they just mimicked from Western tubes.

So, what would be interesting to see if you will be able to show the dimensions.

1) Is any deferens in the traces between new 6E5P and used 6E5P? Sure then might have different current but it would not necessary indicate the use of the tube. Perhaps a combination of the traces along the transconductance and plate impedance would suggest anything?

2) is any traceable (pun intended) difference between 6E5P and 5E5P?

Rgs,
The Cat Hey, how are those discs?


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-12-2007 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,257
Joined on 10-12-2006

Post #: 23
Post ID: 3486
Reply to: 3481
Like he'd just give away knowledge...
I have spoken at length with Modjeski on a couple of occasions.  He is very bright, indeed, and very well educated (MS in audio/elec. eng.), and he is determined to be well-compensated for his efforts.  He tried once to make the "best" amp he could, the original RM-9.  It was a great (PP) amp, but of course the general public didn't "get" it, and Modjeski wound up down-spec-ing it and upping the price some, and then the puiblic "got" it.  Sound familiar?  I gathered he was a little bitter about this, but he is a sharp cookie, and he has ralleyed and made a nice niche for himself.  Of course he will not just tell you how the Ram Factor works!  He sells that proprietary information; marks up the cheap tubes he's screened a la' RAM, and he sells the hell out of them.

BTW and FWIW, of the RAM tubes I've bought, ~25% were bad...

Best regards,
Paul S
01-13-2007 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 24
Post ID: 3490
Reply to: 3485
5V heater?
traces between new 6E5P and used 6E5P

I can make an adapter to trace both at same time.  That will be interesting.
6E5P and 5E5P

Whoops, you mean one of these has a 5V heater?  Which one?

I added dimensions to the previous plot.  My 6c33 sockets also came in.  Maybe I will get some time this weekend to put some of this together.

jh
01-13-2007 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,734
Joined on 05-28-2004

Post #: 25
Post ID: 3491
Reply to: 3490
6E5P vs. 6E6P

Sorry, with me apparent alzheimer-inspired progressing dyslexia…. I’m keep confusing whatever is possible to confuse. What I meant to say was the 6E5P vs. 6E6P. The last one you have in DR version. They are essentially the same tubes with different pins and the 6E6P made with more “precious metals”…..

The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-21-2007 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 26
Post ID: 3525
Reply to: 3491
tube traces coming
Yeah, I'm a little slow here.  Had very busy week pumping out machines.  I do have two custom tube adapter cards built.  One traces two separate 6e5p at same time (great for comparing).  The other is for 6c33.  So it's just a matter of firing things up.

Romy, did you say you only use the tetrodes in triode mode? 

jh
01-21-2007 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,734
Joined on 05-28-2004

Post #: 27
Post ID: 3528
Reply to: 3525
The 5E5P as triode only.
Jim, yes, I use the 6E5P as triode, I never tried tetrodes, never has needs to do it. I have somebody tried them as tetrodes and commented negatively about their sound. I do not know if it is true – it what “they say”. Ironically I do not like how the 5E5P sounds even if it is triode-wired with fix bias. However when the fix bias come form the gas “decoupler”, as it made in Melquiades, them it is completely different story.

The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-22-2007 Post mapped to one branch of Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 28
Post ID: 3533
Reply to: 3528
Triode Curves
Ok, here's some calibrated sweeps.  I ran the tetrodes in triode mode, with G2 strapped to plate through a 100 ohm resistor.  First up is the western 6e6p.



I then built an adapter card that sweeps both 6e6p at same time.  But on my good scope it's hard to see what is going on, as the "dotted line" function was not hooked up.  Easier on my cheap scope.  Makes dueling traces easy to pick apart.  So instead, here's one at a time.  This one is the '63.



And the '62, dark one.  Plate is 50V/div, current at 5mA/div, 1V grid steps.



Note the '63 has much higher gain.  The horizontal spacing is basically "mu".  Interestingly, the 6e6p has lower gain than both of these.  To me, the curves are beautiful.  Spacing is relatively constant, indicating superb linearity.  The tube can also push huge amounts of current.  That is not shown here, as I zoomed in to a 5mA/div scaling.  Previous posts were at 12.5mA/div.  The high slope of the curves means a very low output impedance. 

Each tube here appears to be very good.  I see no anomalies.  There will be sonic differences, as a circuit biased for one of these will be sub-optimal for the other two.  This is a pretty large sample-sample difference. 

Ok, next is my attempt at a 6c33.  Clearly there is not enough grid voltage to sweep this tube.  Again, 50V/div horizontal, but 25mA/div vertical.  The sweep cuts off at 200V plate because there is not enough grid volts.  Lines are at 10V/div.  Starting at 0V.



So I zoom in.  This is at 20V/div plate.  So it still gets up to 200V.  Note the distortion characteristics.  One, the curves gradually get closer together with more negative grid voltage.  Two, the slope changes.  The spacing indicates a nonlinear gain when used in circuit.  The slope means output impedance is changing.  Both will affect performance in an amplifier.  Oh yeah, I wired the tube up to do only one half at a time.  This is the 1,2 heater.



This is same "new" tube but with "7,6" heater pins engaged.



A composite tube would be merely the sum of the currents.  Not a good match between sections.  And now the same thing for the "old" tube.



and



The older tube has less gain.  But something really funny showed up.  And I am not used to seeing this.  On the 76 side, notice the loop in the curve!  This must be some hysteresis.  The curves are generated by ramping plate voltage up, and then back down.  Generally, the two curves fall on top of each other.  In this case, something split them.  I can sweep slower and faster.  And the loop (I forget already) I think is larger at slow tracing (which is supposed to be more accurate as it gives the grid step more time to settle).  My guess is that the loop might be caused by grid current.  I dunno.  However, we may have stumbled upon some practical indicator.

jh
01-22-2007 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,734
Joined on 05-28-2004

Post #: 29
Post ID: 3534
Reply to: 3533
The tube testing show, it is very interesting…

 hagtech wrote:
Note the '63 has much higher gain.  The horizontal spacing is basically "mu".  Interestingly, the 6e6p has lower gain than both of these.  To me, the curves are beautiful.  Spacing is relatively constant, indicating superb linearity.  The tube can also push huge amounts of current.  That is not shown here, as I zoomed in to a 5mA/div scaling.  Previous posts were at 12.5mA/div.  The high slope of the curves means very low output impedance. 

Fascinating! The used up tube has lower gain but we do not relay have clew as we do not have the trace of the same tube when it was new. Since it is Russian tube then even the new tubes might up to 30% difference in gain. Anyhow, I agree that the curves look examplenary, although I have no idea how this “perfect” picture would affect sound. Another interesting observation, and I do not know if I am correct in it, is that the new tube and the used tube have practically no difference in a tracer (the same is for 6C33C) beside their gain. So, are we looking back to measure just cathode emissions?

 hagtech wrote:
Each tube here appears to be very good.  I see no anomalies.  There will be sonic differences, as a circuit biased for one of these will be sub-optimal for the other two.  This is a pretty large sample-sample difference.

Yes, what would be necessary is to measure a couple dozens of them and to learn where is common denominator among the 5E5P…

 hagtech wrote:
Ok, next is my attempt at a 6c33.  Clearly there is not enough grid voltage to sweep this tube.  Again, 50V/div horizontal, but 25mA/div vertical.  The sweep cuts off at 200V plate because there is not enough grid volts.  Lines are at 10V/div.  Starting at 0V.

Actually 200V is enough…

 hagtech wrote:
So I zoom in.  This is at 20V/div plate.  So it still gets up to 200V.  Note the distortion characteristics.  One, the curves gradually get closer together with more negative grid voltage.  Two, the slope changes.  The spacing indicates a nonlinear gain when used in circuit.  The slope means output impedance is changing.  Both will affect performance in an amplifier.  Oh yeah, I wired the tube up to do only one half at a time.  This is the 1,2 heater.

Yes, it is know that 6C33C is not as linear at trace as some other tubes. Once again I do not know how it manifest itself sonically.

 hagtech wrote:
The older tube has less gain.  But something really funny showed up.  And I am not used to seeing this.  On the 76 side, notice the loop in the curve!  This must be some hysteresis.  The curves are generated by ramping plate voltage up, and then back down.  Generally, the two curves fall on top of each other.  In this case, something split them.  I can sweep slower and faster.  And the loop (I forget already) I think is larger at slow tracing (which is supposed to be more accurate as it gives the grid step more time to settle).  My guess is that the loop might be caused by grid current.  I dunno.  However, we may have stumbled upon some practical indicator.

Jim, it might absolutely everything with 6C33C. It is very low standard tube with huge run off of it’s parameters. I would need a couple days to absurd what I see and to interpret how the seen might affect the way in wish the tubes are being used in my amp.

Thank you very much,
Romy the CaT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-23-2007 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,257
Joined on 10-12-2006

Post #: 30
Post ID: 3535
Reply to: 3534
More toys for the well heeled tube-o-holic:
Little I know about tube testing.

Here is a link to one that can do a test series on tubes at rated voltages, including 6C33 (with extra-cost adaptor, of course), and it will compare sections at once:  http://www.amplitrex.com/index.html

Successfully screen only 1,000 tubes you can actually use out of your wholesale lots and it pays for itself!

Not mentioned yet (at least not in a way that allows me to  recognize the information): How are people testing, determining and matching tubes and tube halves for gain, apart from running the math on an "amplication factor"?

And please pardon the simple questions, but

If all I can do with the usual tube tester is check largely irrelevant data, and if the usual sellers take back the duds they already screened with their irrelevant tests performed with the usual tube testers, then what, really, is gained by further testing?

Best regards,
Paul S
01-24-2007 Post mapped to one branch of Knowledge Tree
deemon
Posts 23
Joined on 05-25-2004

Post #: 31
Post ID: 3537
Reply to: 3533
Thermal hysteresis
Hi Jim !
You wrote about "hysteresis" in the 6C33C curves - it seems to be a very interesting point ! Maybe Romy told you about one fault of this kind of tubes - some old ones have a bad tendency of "thermal breakdown" . I mean positive thermal coefficient that may cause very fast ( almost avalanche ) tube overheat . What for me - I noticed it twice when made experiments with 6C33C . And your measurements shows this thermal mechanism . We can suppose that we have some parasitic electron emission from the grid , and when the current grows - the grid temperature ( and this emission ) rises too , but with some time delay . So when the current goes down , the grid temperature is higher than when the current goes up , and we can see this strange "hysteresis" .
Byt what is the cause of this grid electron emission ? One explanation is that some active oxide components from the cathode can "evaporate" and settle on the grid .... who knows , I think that it seems realistic .

Best regards
Dima
01-24-2007 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 32
Post ID: 3538
Reply to: 3537
thermals
Thermals, yes.  That's a brilliant theory!  I need to do some more investigation.  The loops are clearly visible during warmup.  And switching from one heater to the other is wonderful to watch.  I'm going to try and post a video here of it.  The curves as a function of available electrons is fascinating.

jh
01-24-2007 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,734
Joined on 05-28-2004

Post #: 33
Post ID: 3539
Reply to: 3538
The 6C33C’s avalanche heating as an urban legend

Well, it is not necessary a fully qualified urban legend as the problem does take please with fixed based 6C33C but..... only under certain conditions. I have written about it a lot on my site but will very briefly recall it again.

Dima might be correct pointing the reasons for anode overhearing but there is one interesting aspect in it. It is irrelevant if the tube is used up and old one or a brand new right from a box. The 6C33C “go red” ONLY if it is insufficiently heated before it begin to care high grid currant. Trust me guys; I burned a lot of 6C33C. Sine 1996 I used BAT VK60, then ML2, then Melquiades… all of them around the 6C33C (Although BAT used automated bias – it is a different story). I always was very liberal with them – $6 per tube you can do any stupid things for them. So the conclusion that I made is that if do not dissipate on full 6C33C more then 50-55W and let it to burn for 45 minutes before loading the tube with a strong string then the 6C33C does not have any temperate instability and any secondary emission. Sure, with low sensitively speakers when people pump a lot of current across the grid and running the tube “cold” (15-20 minutes of heard make the tube still “cold”) do create the avalanche heating effect. Interestingly is that if the tube was “avalanched one than it will have tendency to do it in future….

Jim, it would be very interesting if you do the following test. Take a half of the 6C33C that you did not overhear yet (currant goes up and the plate becomes visibly red). Heat it for a few minutes (most like as you did) and confirm the "hysteresis". Then reset the plate current and kept running the tubes it for another 60 minutes. I presume that the temperature-inspired "hysteresis" will not manifest itself then. If it is will should up then it will be at WAY higher grid currant (close to full power) and at MUSH lower frequency.  In Melquiades, during the testing I forgot to turn my generator off and a well heated 6C33C (60 minutes) did care for half hour 10H at full power with 55W on plate. Actually it could care longer but it burned the 12R loading Miles 12W resistor….

Rgs, Romy

BTW, Jim, when will we see your version of amp with 6E5P driver? :-)


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-24-2007 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 34
Post ID: 3540
Reply to: 3539
something is moving
I barely put 40W on this plate by testing.  And that's a peak value!  The curve sweeping action results in an average power dissipation much lower.  The hysteresis is there with maybe 5W average power.  And it is only on one side (76 heater) of this particular tube.  I'm pretty sure it is not caused by the tester.  So what is causing this loop?  It could be grid current, as that would generate some small voltage across the 100 ohm series resistance I have at the output of grid step amplifier (total Ro might be about 200 ohms?).  But what would cause it to shift in value?  I like the thermal argument, which didn't occur to me at first because of the exceedingly fast transient response it must have.  For this effect to occur, the thermal has a time constant of maybe 10ms.  Fast.  Maybe a grid wire has this sort of low thermal mass.  And what does the thermal do?  Is it a change in grid current or grid spacing?  A mechanical displacement (like a vibrating grid wire) could be caused by heating/cooling.  Maybe the efficiency of electron generation by the cathode can't keep up?  I'm still at a loss to explain it.

The hysteresis didn't change over time.  It is a short term (1ms to 100ms) effect, not really warmup related.  You'll get a much better feel for this tube after watching the following video.  It is the tube in question with one side heated.  I then switch heating to the other side.  You will see emission fall as one heater cools and the other warms up.  I don't remember seeing loops like this on small preamp tubes under the same conditions.  You can also see the powerful and direct relationship between emission and plate impedance.  Also peak plate current.

http://www.hagtech.com/blog/media/100_1482.MOV

It's for quick-time player (6MB).  Let me know if I should convert this to other format.  Like WMV. 

jh
01-24-2007 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 35
Post ID: 3541
Reply to: 3539
tetrode driver
BTW, Jim, when will we see your version of amp with 6E5P driver? :-)


Well, I have to admit it makes a beautiful triode.  Wonderful linearity, low output impedance, and super-high gm.  Looks a lot like the 6H30, which was my driver tube of choice.  Only this might have higher mu.  Would be a better choice for my "Clarion" design.

jh
01-24-2007 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 36
Post ID: 3542
Reply to: 3540
6c33 internet bandwidth
Sorry for making that video so large.  Here it is again but 1/10th the number of bits.  Compression can be a useful thing.

http://www.hagtech.com/blog/media/6c33.wmv

jh
01-25-2007 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,734
Joined on 05-28-2004

Post #: 37
Post ID: 3549
Reply to: 3542
Jim, would you explain me why does it mean?
I really do not understand what conclusion you make by shutting the tube down. Also, you said that the hysteresis didn't change over time. Dos it men that if you increase the time/div of your scope t have the “hysteresis” delay an itch wide then the hearing the tube for 60Min would not change the length of the “hysteresis”? Dose this hysteresis presented at all 4 halfs the you tried? Rgs, Romy


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-25-2007 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 38
Post ID: 3550
Reply to: 3549
Not on the new tube
I really do not understand what conclusion you make by shutting the tube down.


I make no conclusion.  It's just an interesting thing to watch.  A good experiment.  I was hoping it would be a clue for everyone here.

Since the 6c33 can drive way more current than my machine can trace, I decided to run 1/2 the tube at a time.  I wired in a switch on the adapter card to select between the pins 12 heater and the pins 76 heater.  The hysteresis shown is seen only on one side of the "old" tube.  It is not seen on the "new" tube.  I can only assume the tube in question has developed a problem over time.  The video starts showing the hysteresis (that may not even be the correct word for the anomaly) and ends up showing the good side.  What does it mean?  I dunno.

But I can theorize how this might manifest itself.  In order for the loop to occur, something in the tube has to change pretty drastically.  And in a hurry.  We're talking at audio frequencies.  Maybe mid-bass region.  I don't know if it is a thermal issue, emission,  grid current, or whatever.  But I am NOT driving this tube hard.  My guess is that the distortion would be very audible.  IMD for sure.  It also only shows up when grid voltages are more negative.  That is, more a function of grid drive than plate current.

On the other hand, when the heater is shut down, the loop immediately shows up on all the curves.  That could indicate it is an emission issue. 

jh
01-26-2007 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,734
Joined on 05-28-2004

Post #: 39
Post ID: 3551
Reply to: 3550
The “magic” testing for 6C33C was found?

OK, let me to recall. We learned that the “hysteresis” (for a lack of better world) manifest itself on used tube only. Also, what I see in the images the one of the half of the used tube has more “hysteresis” then other. I think it leads to the following considerations:

1) Your tester might have some kind of anomalies when it drive used tubes (highly unlikely)
2) This given used tube has the “hysteresis” anomaly because it was overheated by me during its service.
3) This given used tube has the “hysteresis” anomaly because it’s a Russian tune and everything imaginable might happen with it.
4) All used 6C33C has the “hysteresis” anomaly because it is a common behavior of exhausted 6C33C

Among all those cases the last one of the most valuable as it might present an objective testing opportunity about health of 6C33C. I think to confirm it would be necessary to run a few other used up 6C33C and to see of the “hysteresis” will be there. If you do not mind I would propose to send you a few other used 6C33C to see what happen. Interesting, Jim, can you elaborate more about how you think the “hysteresisation” of 6C33C might manifest itself sonically.

BTW, I use the shutting down method sometimes in my tube tester. While I measure cathode emission I drop filament voltage from 6.3v to 4V and I have observed that “fresher” tube has less emission degradation.

The caT

PS: Also, Jim, does your tracer have an ability output two independent traces to a dual scope at the same time?


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-26-2007 Post does not mapped to Knowledge Tree
hagtech


Hawaii
Posts 117
Joined on 02-13-2006

Post #: 40
Post ID: 3556
Reply to: 3551
the sound of one trace looping
It's hard to predict how the anomaly will sound.  Sort of like a dynamic bias shift in the tube.  That's why I think IMD.  The shift moves around at LF rates, so the HF reproduction can fall on any number of load lines (within loop area).

Or it may not show up at all.  The loops occur only in one region of the plot.  In a typical amplifier, the load line might be passing through zero here, keeping amplifier operation away from the faulty area.  Maybe the loop happens everywhere, but is only visible at high current, high grid voltage.

Sure, send more tubes.  I also think this one 'faulty' tube is ripe for another test.  As you mentioned, some of your amplifier stages only use 1 of 2 sections.  You should be able to hear a difference between sections in this one tube. 

... output two independent traces ... at the same time?


It can do two tubes at once.  The traces are alternately swept so they appear to be overlayed on the scope.  One of them gets 'dotted' by modulating the Z-axis input of scope.  This function is only useful on smaller tubes, as it depends on total cutoff at -70V grid.  Is this what you asked?  Here is example of preamp tube, both sections swept together in real time.



jh
Page 2 of 3 (45 items) Select Pages:  « 1 2 3 »
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  Hickok Tube Testers: Quick Reference..  Hickok Tube Testers: Quick Reference...  Audio Discussions  Forum     0  16833  08-09-2005
  »  New  How to test 6C33C?..  You might not need it....  Melquiades Amplifier  Forum     7  85525  04-02-2006
  »  New  The 6E5P tube data...  Bartola Valves: 6e5p beam tetrode SPICE model...  Melquiades Amplifier  Forum     44  390150  07-23-2007
Home Page  |  Last 24Hours  | Search  |  SiteMap  | Questions or Problems | Copyright Note
The content of all messages within the Forums Copyright © by authors of the posts