These really, really, look like relabeled Svetlana tubes. Svetlanas run about $15-$20 a tube via ebay. I say seek out Svetlana tubes and save a bundle.
I'm not sure if you are joking?
But these tubes were made in the USSR. You simply can't always believe the text and logos painted on vacuum tubes......
Yup, I've already got enough Russian 6AS7G's
@Ripper2860 is correct that those are Svetlanas. Same as my Amperex labeled ones. The UFO getter is the main giveaway. Personally, I don't think they are bad sounding tubes at all, just not worth premium prices as they can still be sourced cheaply in their native dress.Yup, I've already got enough Russian 6AS7G's
. If you are looking for authentic tubes it's best to check here first (as you have) because this thread has a brain-trust of tubephiles (new word) who can steer you in the right direction. That said if you want RCA tubes specifically I have several matched pairs in various styles that are NOS, tested, and authentic. I think I have some singles too. Shoot me a pm if interested.
Thank you! You are all an awesome group, and I do appreciate your insights!As @gibosi said, these are not made in England. I posted that as joke for the veterans and a warning to unsuspecting buyers such as yourself, so mission accomplished
Good that you didn't go further on those.Thank you! You are all an awesome group, and I do appreciate your insights!
I did message the seller on eBay, I explicitly asked if they were Svetlana tubes sourced from Russia and if not what are their build source, but he doesn't claim any knowledge beyond what is written on the box/tubes. He did offer to drop the price by a few bucks. I didn't bother to offer him "Svetlana money"
I have seen a number of RCA Jan tubes, but none with measurements listed. I'll keep looking
3 warning signs with this seller:
I guess since I looked at the listing, I got an offer too. ROFL!!! I countered at $5 and noted that was a reasonable price for Svetlana 6N13S tubes currently.Thank you! You are all an awesome group, and I do appreciate your insights!
I did message the seller on eBay, I explicitly asked if they were Svetlana tubes sourced from Russia and if not what are their build source, but he doesn't claim any knowledge beyond what is written on the box/tubes. He did offer to drop the price by a few bucks. I didn't bother to offer him "Svetlana money"
I have seen a number of RCA Jan tubes, but none with measurements listed. I'll keep looking
Not everyone is a tube tester savant like you, Bill.So either he doesn't have a clue how to use his tester, or he's just making up numbers as he goes along. In any event, another seller to add to my blacklist.
I think that's the nicest thing you've ever said to me. Are you feeling OK?Not everyone is a tube tester savant like you, Bill.
That's priced very high for an RCA.How about this one?
6AS7G RCA Headphone Amplifier Tube Made in U.S.A Amplitrex Tested #309008
https://www.ebay.com/itm/194795484634
Thanks, but I've already blown my powder on that RCA tube (and a bunch of others!!), so I'll have to patiently wait till next month to try again. Maybe there will be more / better choices next month, and I'll be that much more clued in to take advantage of the opportunities next time.
Well, I'll take a stab at this, but may take more than one post.Thanks, but I've already blown my powder on that RCA tube, so I'll have to patiently wait till next month to try again. Please give me/us some guidance as to what to look for when they do publish measurement results, but don't provide all of the reference values I need to compare for making the purchase decision.
I saw that Sylvania pair, but why don't they list the normal "new/NIB" result as well as the "minimum" so we can tell where on the continuum of values this tube sits? I care about the normal "New" value far more than the failure value. Without both end points as references it isn't possible to know where the results fall in the range of Worn out, to Used, to New.
When I see those results they look to me as in the 82% range of life left, which would be lower than the one I posted, and not acceptable to me, so I passed right by them.
"Condition:--
2 NIB RCA 6AS7G Tubes,pair USA Sylvania branded manufacture--TV7 tested-test nil for shorts
TV7 tested : 36/36 is minimum
TEST : 82/82 and 82/80"
I hear 65% of new result is when to change a tube, but working backwards a 65% value of 55 would be 36, so is 55 the "new" 100% reading? That would mean a 122% value would be about 67... so 82 is 150% of new? What it the 36 value is 50% instead of 65% as the "replace" reference value? That would make 82 114% of "new"...
That's why knowing the actual out of box "New" result would make this much easier - and why the 36 "minimum" as the only reference value doesn't really help.
When comparing the single TV7 measurement result against nothing but a minimum, vs the abundance of Amplitrex A1000 results are like comparing Apples and Pogo Sticks to me, without an existing reference to shoot for how are we supposed to judge the listed results?
I asked the guy with the RCA tube above and he said normal new was 5800 uMhos and this was the highest reading tube he had in inventory - I asked him the month before to find such a tube - and he followed through and contacted me, so I asked him to list it to purchase and he didn't jack up the price over the tubes with lower test results - so to me his follow through counted as much as the test results.
Comparing only the uMhos results - to my thinking - makes those 5040uMhos/5020uMhos results showing about 85%, or is that also not the correct way to look at it? What about the other measurement results from the A1000?, which test values do we weigh as higher in usefulness to consider when deciding which available tube to try?
What is the expected "new" value for the RCA 6AS7G on the TV7?, and what values from the Amplitrex A1000 output should I be using to judge the value of the tube under test?
Thanks again for the helpful guidance.
Update: Ah, so perhaps my "guesstimate" was close? 100 would be actually 100mA on the meter showing a 100% result, and so then 82mA would therefore be "82%"?
https://www.head-fi.org/threads/for-6as7g-tube-rollers-here.410326/post-16212445
https://www.head-fi.org/threads/for-6as7g-tube-rollers-here.410326/post-16212525
And, the Amplitrex printout also printed the mAdc "meter" readings: 105.6mAdc / 89.6mAdc if on the same 100mAdc = 100% scale that would be 105%/90%?, also the highest of that value for all the RCA 6AS7G tubes he has listed, so perhaps I overpaid, but I also got a "newish" tube? In a more perfect field of available choices I would have liked to hold out for 100%+/100%+ instead of the uneven result.
So then how much does looking for the highest uMhos readings play in choosing? As he said the uMhos value of 5800 is considered on the Amplitrex as "new". And, what about the Mu value?, how much does that matter? 1.5Mu isn't the lowest, I've seen 1.7 to 2.0, shouldn't a new tube hit all the "numbers"? Lower results in each section must mean some particular correlation with use/age? Or is that normal variation and "matching pairs/quads" involves judging how the results of each tube fit with the others in the set?
Checking the AT1000 manual, there is a provided "CDROM' with the TUBEDATAxxx.CSV file and tools to read/edit the data and upload it to the tester:
https://amplitrex.com/wp-content/uploads/2017/12/AT1000-Manual.pdf
https://amplitrex.com/included-software/
And, the same for the TV7 I assume, and I've seen little green data cards for each tube to push onto the tester to make the settings.
Without access to that proprietary to each tester information, how are we to tell if the published/listed test results are what we think they are?
Sorry for the long post, lots of items I am learning at the same time, and trying to fit them together.
Any tips/hints/links to set me on the right path? How about an online copy of the Tube data / results tables for the AT1000/TV7?
Yup, all very helpful thank you!, and I also think it will take more than a few back and forth posts over time to help get *me* aligned/calibrated.Well, I'll take a stab at this, but may take more than one post.
First, I can't speak to the Amplitrex as I have no experience with one, and don't really know what the 'Mu' value signifies. The vintage testers (Hickoks, Simpsons, Westons, B&K's, Knights, Sencores, etc etc) specify either a NOS value OR a minimum good value for the tube under test. I've never seen one list both for the same tester. And even within the same manufacturer's lineup, some testers list NOS (Hickok 800A for example), or minimum good (Hickok 752 and TV-7, for example). The general rule of thumb is that the minimum good value is around 60% of the NOS value. So if you have one data point you can calculate the other, but it may or may not be accurate depending on how the manufacturer arrived at the values. As such, any calculated value used in a sales listing should be labeled as such as it is at best an educated guess. My Hickok 752A lists minimum good values, but they vary from 61% - 64% of data sheet NOS depending on the tube. Accurate as a hand grenade, right? Remember that the bulk of these vintage testers including the much loved (I-have-no-idea-why) TV-7 are not laboratory grade testers and were never intended to be. They were made for portability, easy on-site operation, and to provide useful information -- not ultimate accuracy. Then you have to deal with the fact that some testers provide a GM number that actually matches up with tube data sheets, and some that just use arbitrary numbers (like the TV-7 and most B&K's). Without knowing what the tester's published values are (and mean), any GM figure provided by a seller is worthless unless you go to the lengths to try and figure it out. Ideally, a seller would list the make/model of tester they are using, when it was last refurbished/calibrated**, what the reference data number is and whether it's NOS or minimum good, and then the tube's reading(s) compared against that.
** The bulk of the vintage testers are 50+ years of age at this point. Modern electrolytic capacitors have a normal service life of 25, maybe 30 years if kept within temperature specs. No telling what the service life of electrolytic caps was back in the '50's and '60's, but I think it's safe to assume it's probably less than modern caps. So if the capacitors have not been replaced (at a bare minimum) at this point, any readings obtained are pure garbage as the caps will either be way off spec or totally dead and the tester will not calibrate correctly (I've refurbished a couple dozen testers in the past 5 years and every single one has had at least one dead or way out of spec cap, and most had several). Sorry for the long aside, just an important piece of the puzzle if any faith is to be placed in the test data.
As far as determining what the NOS value should be, that is typically provided in the tube data sheets that can be found online pretty easily. The first one below is for an RCA 6AS7G, and the 2nd for a Tung Sol, both showing a transconductance (GM) value of 7000 which would be the "bogey" value:
http://www.r-type.org/pdfs/6as7g-1.pdf
https://frank.pocnet.net/sheets/127/6/6AS7G.pdf
So was the guy lying to you when he stated 5800 as the NOS value for that RCA? Maybe, but probably not. 5800 is most likely the number that HIS tester showed as the NOS value for THAT tester. Manufacturers arrived at their own values in many cases to correspond with the electrical workings of their particular tester. Long and short of it is that you cannot easily (or even at all) compare the test numbers between two different manufacturers and/or models of tester, as their baseline data may be totally different.
Below is a good site that has lots of tester info and settings data. The first page lists the manufacturers, and drilling into those gets you to specific models. There are a number of other sources as well, this is just the most comprehensive and so the place I always go to first.:
http://bama.edebris.com/manuals
Not sure if this helps or just confuses things more, but fire back with any other questions or anything I glossed over.
