[bcowen]

.

 

[bcowen]

.

 

[bboris77]

I just purchased a spare new production tung sol and as soon as I opened it I saw a small particle floating within the frame of the tube. It looked like dried glue or a filament of some sort. When I shook the tube, there was a very slight rattling sound. I did not even plug it into my amp because I was scared of damaging it or the headphones. I contacted the seller and asked for a replacement.

My question is was I too paranoid or was my instinct right? I’ve bought many tubes before and have never seen stuff floating inside the glass before.

 

[bcowen]

.

 

[mvn1]

Hey folks,

I wanted to report some of my experiences with NOS tubes in the Lyr3, as well as ask some opinions on my next batch.
I tested these over a number of different music Genre's, including Classic (piano), Rock, and a broad range of modern music.

6SN7GT - VT-231 JAN Ken Rad, blackplates, blackglass (1940's) - What a tube - so well balanced. High's were perfect, could reach those high notes without fatigue or rattling my inner ear to wincing point. Bass was super tight, deep, without going overboard. Mids were well defined. If this was my only tube, I could totally live with that! It also was a bit 'quieter' than other tubes.

6SN7GT Sylvania 3-hole 'Bad Boy' - When I first heard this tube, I loved it, but over time, I've come to realise that while the bass is fantastic, and the mids are pretty good, the highs are a little fatiguing. All in all a great tube but for extended listening sessions of anything with significant highs (think piano, classical), it gets pretty tiresome. Still worth picking this tube up if you can!

6SN7GT RCA blackplate, grey glass, late 1940's - This tube has surprised me the most - and has had the biggest transformation since having being burnt in. In fact, this is my daily driver tube, well rounded. The word 'beautiful' comes to mind, but unlike the top two, the lows are less pronounced. I am planning to purchase a pair of these for a future Freya pre-amp. This is worth picking up!

JAN CHS 6SN7 GT VT 231 Sylvania Tube 1944 - big caveat - I picked this up used so please don't let this commentary make or break your decision. Having said that the seller was reputable and it did test ok. I've heard great things about this tube, but for me, it wasn't as 'exciting' as the tubes above. Earlier in this thread someone made the comment about this tube that when listening to it, they may as well go and watch TV. While I disagree, it certainly isn't one I'd buy again. The high's had more of a 'ring' to them than I was used to it (when listening to some piano tracks i.e. Luke Howard), and I found myself fatiguing. The soundstage wasn't anything to celebrate either.

6SN7GTA Mullard - Made in Australia - I picked this one off Ebay, again used, but I was surprised Mullard made tubes in Australia! Overall, a pleasant tube to listen to, Lows were very present, but not like the 'Bad Boy' where you could feel your eardrums vibrate, and the low's weren't as tight as the Grey Glass RCA. Mids were warm, and the high's were contained and fine.

So now - I'm looking at the next round of tube purchases. Can anyone comment on any of the following:
5692 JAN CBS-Hytron brownbase, short glass envelope, 1950's/1960's
6SN7GTA early "Tall Boy" type, Sylvania Triangular Plates, Sylvania green label, early 1950s (I haven't head raving reviews about this)
SN7GT - VT-231 JAN Raytheon, blackplate greyglass, 1940's
6SN7GT TungSol made Mouse Ears - late 40's early 50's/

Your expertise are appreciated!

BTW, for anyone wondering, I purchased. my tubes through Brent Jesse, except for the last two. Brent has been great and I had a tube with crazy microphonics - he has replaced this free of charge!

 

[ilikepooters]

Don't know if anyone can help me here, but anyone know where i can get a 6SN7 with guaranteed specs, preferably in micromohs (like a standard tube)? Want to see how far out my Hickock 800A is and i don't have a tube i can trust.

 

[bcowen]

.

 

[ilikepooters]

Upscale Audio might be able to help.

Better though to check the 800A for calibration:

http://www.radiolaguy.com/PDF_Files/Hickok800-800Acalibration.pdf

If you have a decent DVM, all you'll need are a 250k and a 1 megohm resistor. I wouldn't fret with anything past step 10...if your tester's readings are good at those test points, your tube test results should be darn close to spot on. You don't even need to remove it from the case -- all these tests are done from the top using the octal socket. You will have to open it up if any of your readings are way off which would indicate something needs adjusted or replaced.

I have a Fluke 179.

Where it says "shunt resistor" does that basically mean test the voltage through the resistor instead of directly? Have the Fluke for work but as you can guess i don't use it very often

 

[bcowen]

.

 

[ilikepooters]

You want to use the resistor in parallel with your meter probes. For example, on the plate voltage check stick one end of the resistor in pin 3 of the octal socket along with your meter's positive probe, and put the other end of the resistor in pin 8 along with your negative probe. There's just enough room to put both the meter probe and resistor lead in the hole and make good contact. Without the shunt resistor your voltage readings will be very high (over 170vdc probably on the plate test). Today's meters have a very high input impedance compared to what Hickok used back in the day and the resistor helps approximate the difference. In steps 1 - 10, use the shunt resistor for steps 5, 6, 7 and 8. Do NOT use it for steps 9 and 10 (use meter probes by themselves). Also pay attention to AC and DC test settings.

Looks like i'll have to join up a couple of lesser resistors in series for the 250K, can't seem to find one of those anywhere.

 

[bcowen]

.

 

[ilikepooters]

Found some 5w 1 meg but only 5%

https://www.ebay.co.uk/itm/MOF5WS-1...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

have some 1/2w coming as well, 100k, 150k and 1 meg.

 

[Scrith]

Just a quick note from my tube rolling today... I just heard a Mullard ECC33 (sorry, I typed Brimar before fixing this post) for the first time after starting with a 3-hole Bad Boy (my current reference). Wow! It's quite impressive...I am hearing the strings on the bass vibrate like I've never heard before (on a recording I listen to daily). Not to slight the Bad Boy at all, this one just takes it another step further, possibly a bit less bright (which is fine). OK, back to rolling!

 

[bcowen]

.

 

[earnmyturns]

Puzzling tube behavior. Got home, turned on Lyr with Sylvania 2-hole Bad Boy, which was sounding great yesterday. Did not listen. Went to have dinner and talk about the days with my wife, came back to the Lyr around 1h30m later. Put on my headphones, before starting any music, and I heard a low high-pitched, variable, scratchy noise on the left side. It changed as I adjusted the volume. Turned off the Lyr, listened for a while to the Apex Peak. Let Lyr cool down, removed the tube with disposable vinyl glove, reseated it. Turned on Lyr, waited for on click. Weird noise gone. What's strange is that the tube was well seated originally AFAIK. Any suggestions?