Tube Lab #7 12AT7 Rolling for 12AX7

[@TheBaseUK]

Thanks for this man, new to tubey amps so seeing these sort of things is super helpful, hope you keep it up!

[@collinkody3122]

i know Im asking the wrong place but does someone know a way to log back into an instagram account..? I stupidly forgot the password. I would appreciate any assistance you can give me.

[@braydonnathanael4541]

@Collin Kody instablaster ;)

[@collinkody3122]

@Braydon Nathanael i really appreciate your reply. I found the site through google and I'm in the hacking process now. Looks like it's gonna take a while so I will get back to you later with my results.

[@collinkody3122]

@Braydon Nathanael It did the trick and I actually got access to my account again. I'm so happy:D Thank you so much you saved my account :D

[@braydonnathanael4541]

@Collin Kody Glad I could help xD

[@thomkopal1740]

For those of you actually wanting to use a 12AT7/ECC81 as a substitute for 12AX7/ECC83 in a slot designed for that 12AX7, please keep in mind that the 12AT7 will not bias properly under the 12AX7-design conditions. It's okay to try it out, but, in my experience, most folks trying this go back to an actual 12AX7. The basic complaint is that the 12AT7 sounds very bright, very thin (not enough low-mid & bass) and, of course, very weak. There is one exception to this: the 1980s Mullard CV4024. That CV4024 is usually also marked with "M8162" and "12AT7WA" and it was made in Mullard's Mitcham plant (factory etch code "R"). This is NOT the Mullard M8162 shown in this video, however, as that one was made much earlier, as indicated by the older Mullard logo. Look for the most commonly available Mullard CV4024/M8162/12AT7WA with the later style Mullard logo, and you will get a 12AT7 that retains a rich, thick tonal character that can be suitable when you sub it for a 12AX7. Also... I'd like to say a good word for *slight* microphony. A little bit of microphony adds a dynamic character to audio pathways that make them sound more lively. This adds to musicality, in my opinion. Microphony is NOT "noise" - noise is caused by dirty pins, inadequate electrical contact, degradation of the cathode, and other factors that result in random hissing, spitting, or flurries of crackles. Too much microphony can result in squealing, with sustained notes that are not related to the audio signal frequency in a musical way. If you tap your tubes and fear that they make pinging noise, just stop tapping them ;-)

[@tubelab194]

Thanks for well written and informative comment! I've come to the same conclusion as you, with regards to microphonic tubes. A little can really enhance the sound - up to a point as you mention as well.

[@PGHJR002]

@@tubelab194 Try the 5751 tube as a direct sub for the high gain 12 ax7...I recommend RCA(NOS) or TUNG SOL(NEW RI)

[@Blueguitar007]

​@@PGHJR002yes. 12at7 no good for tone. 12ay7 is good even lower output than a 5751 and good for tone. I'd never put a 12at7 in an x7 slot... they just awful

[@frankgeeraerts6243]

Most ECC81/12AT7 's have a chrome shine on the sound............not so with 6201 triple mica GE , ECC801s TFK, RCA black plates and that fabulous Mullard M8261 ( the regular Mullard is ot so good sounding to MY taste ).........another very good and smooth sounding tube is the VALVO ECC81 !!!!

[@wmk0100]

I like your videos. They are very informative. I don't mean to be disrespectful, but try to hold your hands still, while your holding the tubes.

[@tubelab194]

Yes, it is a problem, when I get excited I shake! Someone mentioned this way back at the beginning and I've tried to be aware of it! See how I do on Friday.

[@prakashcj]

Thanks very much for this very educational video. I am looking for a 12AT7 preamp schematic - any help is much appreciated, please.

[@tubelab194]

This would be a good question for one of the online groups dedicated to building your own tube amps - many to choose from!

[@yaveeya2992]

I heard using a 12at7 will give you more headroom.

[@MercedesGuy1954]

Hi There, I bought a box of old tubes and it had a pair of IBM Lettered clear top 6211 side getter's. Yjt hav the numbers 6J-35, 188-4 and 255551 in white, same as the IBM lettering on the body of the tube. On the clear domes is 170C in yellow paint. I replaced ElectroHarmonix, goldpinn 12AX7's in my headphone amp and the bass is lower, tighter and quicker. liquid midrange and a lovely 3D image scape than the EH'sI have never heard of them before I tried this. Are there other 6211's as they trounced a few NOS 12AT7's I tried too.

[@tubelab194]

I have very little experience with the 6211 so can't help.

[@switlikbob1]

Great videos!! Thanks for making them. Do you sell tubes?

[@tubelab194]

Yes, I sell tubes, it is my passion and business, Tube Lab is a result of my experiences starting out in Tubes and how much of the beginner stuff I didn't know, and wasn't the focus of other KZbin channels. Hint: it is always worthwhile watching till the very end of my videos!

[@Blueguitar007]

Im no expert but i thought the 12at7 shouldn't be used for anything that affects tone...only for inverter and reverb driver

[@tubelab194]

When it comes to rolling in tubes that are reasonably close to each other the only rules are, if it works ok and sounds good, you are good. You only get into real trouble when you start plugging completely different tubes in and hoping you don't see smoke! Don't do that!

[@yaveeya2992]

The hand movement is killing your video. I AM TRYING TO LOOK AT THE TUBE. AND YOUR GIVING ME A HEADACHE. THANKS FOR THE VIDEO THO.

[@tubelab194]

Yes, this video was made about 2 years ago, when i was just learning and your comment has been repeated many times! As i got more experience things improved.

[@LEON4PRES]

Can you guys help me out? I'm thinking about building a small, high gain guitar amp. Maybe 5 or 10 watts maximum. Can you guide to where I can find parts and pcb's? Guys like Mojotone and others all have whole kits for what I could buy low watt Fender or Vox. If you go into Bugera or Monoprice, they're actually cheaper than the parts from the DIY guy's. THANK YOU!!

[@tubelab194]

If you buy a quality Kit you're basically buying a guarantee of support that you'll get your amp working properly. A quality Kit will also be well designed and work as well or better than a factory made amp. I'm of course speaking from a position of both experience and bias, given that we design and manufacture Kit Amps. In audio as in everything in life, you basically get what you pay for. If you have a lot of time and a very low budget, find a blog from a builder and buy in the parts, but don't be surprised when you buy quality transformers, chokes and a nice chassis that you've spent as much as a nice Kit and you still need to get the circuit working. We spend 6 months to a year developing a single Kit amp and making certain it works perfectly and sounds great. Any schematic you work with, even a known one will require time and experience to get working properly - many projects started like this are never finished or never work properly. So my advice is save up your cash and buy something really good.

[@LEON4PRES]

@@tubelab194 COOL, I should have looked you up before I asked my dumb a@@ question. Thanks.

[@RJ_Chicago]

Hi Jim. Can one safely replace a 12AU7 with a 12AX7 or a 12AT7? Thanks.

[@tubelab194]

A Good Question! And the short answer is NO. Even though the 12ax7 and 12at7 have exactly the same size bottle and pinout as a 12au7, they are very different tubes. The 12au7 is a medium gain tube (mu or gain of 20) and the 12at7 and 12ax7 are high gain tubes (gain of 70 and 100). Gain is simply how much voltage the tube can amplify, this is always expressed as the design maximum or as I like to say "nominal maximum". The tube will almost never be biased to the maximum. So as an example, if you had a preamp and put a nominal 2vac in from a cd player and your gain tube was a 12au7, with one gain stage, you could potentially get 40vac out at max gain (2v x 20 gain = 40). Or if you had a phono stage and your cartridge output was 10mVac (10/1000v) and you had a single 12ax7 gain stage, you could potentially get 1000 mV (1vac) out (10mV x 100 gain = 1000mV/1v).

[@josephtiongson2305]

I get dizzy watching this video while you try to show the etchings.

[@tubelab194]

My apologies, I need to slow down when moving objects during filming and trying to show a detail.