Tube Lab

[@peterharman8466]

For me the at7 especially smooth and clear beautiful sound

[@georgecovetskie6717]

The GE 1960 / Sylvania 12at7 was the best, pleasant sounding.

[@thebeaner687]

Sounds awesome, love how beautiful and organic everything sounded

[@6643bear]

Hi, great video, I bought gz30 40 years old for my " RCA AR88 communications receiver , it was nearest rectifier tube to make my receiver work , I think sorry was a long time ago a cold start tube , regards Mark

[@BradRocker]

GE was winner for me. Nice and layed back smooth

[@tubelab194]

I agree, high gain tubes can be a little edgy, the GE has a nice warm round sound, something very common with vintage tubes and unfortunately not common with new issue tubes.

[@GtrPknMama]

You guys are really setting the hook….lol😎👍🎵

[@ecc8344]

Awesome! Thank you for another 12ax7 video! :)

[@terjeaudio4308]

Hi Jim and Charles, great video like usual. Both the Sylvania and the GE sounded lovely, but I have to give it to the Sylvania, but then I might change my mind when I play the video again haha...cheers Terry

[@tubelab194]

Thanks, when we have a minute we'll put a high res version into the tube listings and a link below the video. We record in 24/96 and I'm still surprised at the quality of a "live take" direct off our equipment rca outs. The original recordings though are very good, which certainly helps, I spent an hour auditioning tracks Thursday night and had two good options (we never know which recording will accept royalty sharing in exchange for free use). In the end both tracks passed and I said "they're both great, let's just use them both!".

[@jeffbrooke4892]

I am curious of your thoughts on Matsushita made tubes, especially the 12AX7. As I understand it, the Matsushita plant was set up by Mullard and used much of their manufacturing equipment.

[@tubelab194]

A lot has been made of the connection between Matsushita and Philips/mullard. In the early 1950's Philips entered into a partnership agreement with Matsushita, for a 30% share of Matsushita, Philips got access to the Japanese market and Matsushita got access to Philips tech. However in my experience that didn't mean that Matsushita started making mullard or Philips tubes. Yes some of the equipment looks to have been supplied by Philips/mullard but in most cases the tubes don't look or sound anything like the European versions.

[@jeffbrooke4892]

@@tubelab194 Thanks, I appreciate you taking time to answer my question.

[@alanpecherer5705]

The RCA 5AR4 is a rebranded Sylvania, I'd bet, with those smooth plates. 5AR4s are generally very pricey in US-made NOS, but a straight sided 5V4GA is an acceptable substitute in my book with the very low voltage drop and slower warmup.

[@reportingfromthebunker]

Yeah. Definatley Sylvania. I have some 6L6 GC's with the same lettering font etched into the glass.

[@alanpecherer5705]

@@reportingfromthebunker You're right, the strongest clue is the print/font of the tube type "5AR4/GZ34" on the side glass. Total Sylvania.

[@jeffbrooke4892]

Thanks. Another great video. I consider you guys a gem in the subject of vacuum tube hifi. I have a DIY preamp (tube4hifi SP-8) that uses 12AU7s in the line stage. I had a set of 5814s, but one went micrphonic so they need to be replaced. My question has to do with tube interchangbility. Can 12AU7s, AX7s and AT7s be interchanged? I never thought so. But if so, it opens up my options for this preamp. Thanks again!

[@tubelab194]

Not normally, however the 12au7 had many variants that are all options. But i would point out the actual 12au7 is the most common tube ever made (basically a modern 9 pin 6sn7gtb) and the selection is enormous, so why not simply use them. We specialize in them and have a great selection of organ grade and many others to choose from. Now the 12ax7 has a couple of 2nd cousins with identical pin out and fairly close operating parameters, like the 12AT7, so that's a reasonable tube to try, especially given the cost of the vintage 12ax7's!

[@nealsturges]

How DOSE A 6681 GE TUBE 12AX7'' COMPAIRED TO 12AX7A 7025 TYPE TUBE FOR SOUND QUALITY AND GAIN ETC ? THE SHUNT SETTING FOR THE 6681 IS 11 AND THE 12AX7 A AND ALSO 7025 IS HIGHER AT 14 ON THE TESTER CALIBRATION CHARTS '

[@tubelab194]

The 6681 is just a ruggedized 12AX7 and a vintage 7025 is just a low noise 12AX7. Modern 7025's are just 12AX7's with a different name. So they're all basically the same tube, with exactly the same electrical properties, so they should all be tested at the same operating point. Sometimes a ruggedized tube is a good thing, ie as a power tube and sometimes it's not like when used as a preamp tube. The reason for this is ruggedized tubes often have very low noise and very low harmonic distortion, which is what brings life to a preamp tube. But in the end determining what sounds best will require a Fun critical listening session!

[@neccron9956]

What you call a Mullard flash is not a good thing. It is a flaw in the construction of the filament in which, when cold, there is a hot spot on the filament (causing that spot to heat up faster then the rest of the filament). When warmed up (resistance increases), it will run normally. But, it does reduce the life of the filament.

[@tubelab194]

Actually in the case of the Mullard small signal tubes that have the flash, they were pretty much all made that way. From what I've read, they stripped a wee bit more of the filament coating off down near the connection point and that created the change in resistance that causes the surge and flash. From a technical standpoint, i would normally agree that this looks to be a flaw in construction and possibly even reduce filament lifespan. However I've never had a single problem with a mullard filament or even seen one die prematurely and given who Mullard was as a manufacturer, I think this is the way they wanted them to operate.

[@cgavin1]

I've had a British Mullard 12AT7 in my 1973 Fender Twin Reverb as phase inverter since 1975. It flashes brightly when the amp is taken out of standby. Its been doing that for 48 years and about 10, 000 hrs.

[@frankgeeraerts6243]

IT is NOT a flaw ....................but a different kind of filament !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I had people refusing these tubes for NO reason ! As seen the same ignorence of tube technology with blacked , dark gettering instead of the classic shiny ..............in reality the darker getters are the better tubes , FACT !!!! and flashing filaments were made among the very best nos brands. Today everyone seems to be an expert on tubes and vinyl /analog ............beliefs and false information poisons the audiophile community . One thing for shure , you CAN NOT argue with beliefs.....

[@frankgeeraerts6243]

@@dougulman6700 Indeed DOUG !...................the new experts of tubes think they know it all ( false beliefs hahaha )

[@tubelab194]

@@frankgeeraerts6243 you need to tone it down, your experience is always welcome in the comments, but it needs to be shared in a polite manner. Making a point with one exclamation mark is acceptable - if it's not at the expense of someone else - using 20+ is not polite. This is a first warning, I don't give second ones.

[@dougulman6700]

I have a few of those long plate ge's and they really punch above their weight in the v1 on my amps....will u be testing all the at7 wc u sell?

[@tubelab194]

Yes they'll be tested. We always electrically test our tubes and IF we have an amp to play them in we do a "live" test for low noise and quality sound - it really slows down filling orders, especially on a busy day, but in the end it's worth it, to know we are shipping a quality product and I sleep better at night!

[@GiantRock62]

What's the difference in sound of long and short plates in let's say 12AX7?

[@tubelab194]

Every tube is different, when we talk about a long plate version of xxx tube, it's more of an orientation description of the variant than a statement good/bad. For example the short plate mullards sound excellent, though with a higher noise floor than I'd like and the long smooth plate Telefunken are also excellent sounding tubes.

[@solarman30]

That GE sounds SWEET! Is it quiet enough for phono preamp use? Thanks for the videos 😀 Dan

[@tubelab194]

I would think so, we had them turned up high in the preamp and i couldn't hear a thing! Note, much of the noise in a phono preamp is the power supply, design, layout and components, and even a perfectly quiet tube can't fix that 🙂.

[@jimcatanzaro7808]

Every tube is subjective of everything there not all the same speakers are not the same voltages change parts drift in tolerance if it sound good it’s good just test them and use em

[@PetraKann]

Never confuse good music with good sound

[@tubelab194]

On point, thoughtful and polite discourse are always welcome in the comments. This doesn't qualify, at the very best it's a passive attack on our methods. If you wish to elaborate (as already requested on a similar post) that's fine, so long as it meets the above criteria. Consider this your first warning, I don't give second ones.