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This is an idea I've been toying with for some time.. building a dedicated tube tester for Atma-Sphere equipment. I'm curious if there would be enough interest to make it worth the while to build & sell a run of them.Very few knobs or switches.. dedicated test sockets for 6AS7, 6SN7, and 12AU7/12AT7. Transconductance test for the small tubes, real-load DC test for the power tubes.
Alternately, omit the small tubes (since they are easily covered by any other tube tester) and build only a dedicated 6AS7 tester, that tests the devices under the same load conditions that are seen in the equipment. This might make better sense, as I know of no tester that can test a 6AS7 under real loads.
Finally, what would a reasonable price-point be for either of these two proposals?
Follow Ups:
I'm interested! Are you still considering building the tube tester?
of being able to test the small tubes as well as the output tubes. Although I have a couple of tube testers, a single unit would be preferable. The real-load test for 6AS7s sounds like a great idea.
This is the one to get fellow inmates
wow prof! if i only had $2200 bones burning a hole in my pocket... ;-)
...sounds like a great idea to me! To be able to test both small and large signal tubes in a single unit would be very convenient.
Option one would be my preference but, certainly, either option is better than neither. I don't own a tester myself but due to the continued graciousness of a local high end audio designer, have been able to get my hands on a properly calibrated Hickok 532 when the need arises. That being said, I know it is compromised when it comes to evaluating 6AS7s. Duke, maybe you, cmathes, and I could get together on one of tese things if it becomes a reality.
Several people have remarked that a 6AS7-only tester with multiple sockets (like 8 at least) would be desirable.The tester could be used as a burn-in rack as well, in either filament-only or under-load modes. When under-load, you could just rotate a selector to compare the tubes based on plate current. Current would be read as a voltage across some small (1 ohm) cathode resistor.
I do like the idea of testing the small tubes as well.. but it would add a lot more complexity to the tester. I need to sketch out some concepts / schematics and see what can be done, within the $500 price point I'm trying for. There has to be an elegant / clever way to do this..
Actually, I would be more interested in Option 1 than in a 6AS7-only tester....as I believe most others would be as well. The reason being that, although many or all of us already have testers (in my case, an H/K TT-1a), in many cases those testers are showing their age.While I have replaced aging caps and sundry other components in mine and know it to be properly calibrated, many others are using testers with aging componentry which in many cases are dodgy at best. Not to mention the added convenience of not needing to drag out two different testers to check your entire complement.
I might also mention (since we're presently only brainstorming on this) that...if one were to to do this, it would be best to do it right. In other words, not just transconductance of each individual triode...but also simple tests for things like grid current leaks, heater cathode leaks (something I have found a great number of new 6SN7EH tubes suffering from fresh out of the box), and etc, at operational currents and loads.
Yes, I know...asking for the moon.
Aaa-Men. I have now run through about 8 6SN7s for the MP-3 and they all have problems, mostly the leakage thingy, I think. This is annoying. Help!I have a picture of the tip jack mod on my former MA-1, MKII if I could figure out how to post it.
I think the idea has real merit, myself. I have a 539C, but it only tests emission for 6AS7's. I have set it up in the past to test mutual conductance of 6AS7's at close to the Atma operating point, but I think it was a strain on the tester.Another possible use: Burning-in 6AS7's prior to use in the amp. If the unit has sockets for six tubes, and could operate in a "filament only" mode, this would be very helpful in preparing tubes for service as many have recommended over the years for longevity.
It would be nice to be able to sort tubes quickly with such a tester.
Option two makes more sense than option one since there are testers already for the small tubes.But option 2 doesn't make much sense to me when you can just use the amps to test the sections of the 6AS7 (I'm assuming that is what you mean by DC load test). Why not just include the test tip jacks in atma-shere amps in the first place? Seems like a simple, cheap thing to do, that adds real value to the customer. And they are pretty much invisible. Maybe only put the jacks in the back rows of an amp if asthectics are impacted. Is there a safety issue with this?
One final thought. Rather than building a batch of testers up, why not offer a 6AS7 test service at the 'factory'? Might be too much of a hassle I suppose.
The primary reason for making a tester that does both the small triodes and the power tubes, is that the owner might *not* have access to a tester for the small tubes.As far as using the amps themselves as testers, there are two issues:
1) Wear and tear on the sockets in the amps. Wearing them out from tube-testing use is not a nice way to treat the equipment. Replacing 16,28, or 40 bagged-out sockets is not a cheap operation.
2) Using the amp as a tester for small groups of new tubes isn't all that practical.
The idea of using tip-jacks isn't a bad one, in fact, we're doing a custom mod on a pair of M-60's right now, that incorporates installing a tip jack for each power triode section. There is no real safety concern, as the jacks are just a volt or two above chassis potential.
That said, installing jacks on every piece of equipment will result in a price increase; something we try to avoid. Aesthetically, they are not too bad, but there is another issue.
A prospective buyer looks at an amp with 16 or 28 jacks on it, and the logical assumptions are 1) they are there for a reason 2) I will need to stick something into them on a regular basis, maybe just to check bias 3) I will have to understand the how & why of it. These are not good selling points, IMO.
Again, I just brought this up for the sake of groupthink..
Perhaps a 6AS7-only tester, with like 8 sockets in it.. so that whole batches can be quickly compared? Just thinking..
About $500 max, I'd be game for a 6AS7G tester
> > Again, I just brought this up for the sake of groupthink..\Well, I guess we'll see how much of the asog spirit lives on here.
As for what potential customers would think about the jacks I see what what you are saying, and you are probably quite right. It's too bad that people wouldn't see this an 'feature' rather than something scary. How many amps on the market allow you to measure how tube sections are actually behaving in the circuit? That's a damn selling point to me, but to someone not familiar with the amps it would probably scare them off. I installed jacks in 4 positions in one of my M60s so I can measure batches of 4 with ease. I've found some wild section mismatches this way. And I have not noticed any wear on the sockets yet, but thanks for the heads up - I hadn't thought of that.
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