12AX7 vs. 12AT7 vs. 12AU7 in V1 and V2: Distortion/gain tube comparison

[@JonDeth]

Someone mentioned that switching to an AU7 but slamming it with a gain pedal like a tube screamer will actually give you more tube distortion texture than an AX7. While the gain factors are respectively 17 and 100, when you run active devices at the top of their specifications, you get them to compress and clip the signal. With the gain factor of the AU7 being so low but power dissipation being in fact so high, they probably clip a lot harder than the AX7 when you max them out and then slam them with a high voltage input signal from another circuit, but I will also admit I've yet to try this. *BTW, I'm a college educated electrical/electronics engineering, but it takes a lot of time and cash to test every concept out there lol.* I love tubes and my tube gear, but my raw overdriven transistor designs actually produce an identical sound to tubes, but di it a bit better.

[@davidlalremruata]

the 12AT7 is perfect for the rhythm guitarist in the background

[@khrys_maxwell]

I like how the AU softens the top end in V2

[@digitalchris6681]

Great video. Sort of a scientific analysis. I'd already swapped V1 for an AT. Not to reduce the gain (=distortion) as such, but to reduce the hiss, which it does. The VC50 is a seriously underrated combo. But on the positive side, that means you can find them at knockdown prices..

[@alexbozas887]

great comparisons...i really liked the illustrations... and the tonal variations

[@j.f.brunet6218]

Thank you so much for this video. Finally a worthwhile and well put together comparison!

[@littlebritain64]

This is a very good way to compare anything on KZbin. Well done!!

[@LeMans512]

I always wondered what would happen. Now I know. Well done. 👍🏼

[@Cluless02]

So I thought the best config was 12at7 in V1 + 12au7 in V2. Will have to try it out on my HIWATT! Very professional vid!!

[@cirjames2540]

Great video. I have been wanting to tweak the tubes in my 6505 MH since I got it recently. Swamping out for a Au7 in the V1 position makes sense to my ears.

[@joetoe9207]

Very helpful; thank you for doing this!

[@dv8r892]

this is brilliant. thanks man, exactly what i needed to hear before taking the plunge, well done!

[@washit1st]

Outstanding presentation ... clear and very intuitive ... thank you !!

[@philipbowley8374]

This is brilliant, can't wait to tame my Crate Blue Voodoo's gain channel.

[@giulioluzzardi7632]

It all helps. Even an amp with 2x12ax7 in v1 and v2 simply swapped around can make a cruddy sound into a WOW wtf sound. Building a blackface type amp I ended up with; 12T7 in v1, 12Ax7 v2 and V3 then 12 At7 for v4 phase inverter and it gets that compressed high end and looses the brittle metallic headache sound too. Very simple no Tremolo circuit, just Reverb and vol. Bass mid treble. 2x6L6 and Jensen P12Q and a slightly wider cab to get the warmth. Thanks for your demo.

[@petset77]

Overall, I like the AU7 in every situation other than pushed to eleven. ...I'm here looking for comparisons to upgrade a tube pedal. Thanks for the vid and info.

[@philhardcastle172]

Great job on this!!! You can definitely took the time and effort to put together this video which was very informative. I have subscribed to your channel. Keep them coming!!!

[@lorencing]

Excellent video, thanks.

[@lars-fenin]

cool /helpful comparsion/ examples. i like the au7 in v1 (i did the change in my hot rod deluxe) much better control for me.

[@WhaleBluePRS]

I have a Vox AC30S1, too much gain for my purposes so I'm going to grab a new 12AX7, 12AT7 and a 12AU7 to experiment in the two positions. (Digital reverb and solid state rectifier, so only 2 tube to experiment with. Good for the "newb" here!). Really looking forward to hearing each combination/permutation of the tubes in my amp. I already replaced the EL84s with a set of matched Tung-Sol and it's much better than stock, eliminated the dreaded "frying egg" sound of the AC30S1 from the factory. I run the master on 10 and adjust the preamp gain to saturate to taste for the part I'm tracking. This helped a ton, thank you!

[@wingsofsilver9349]

Nicely done. While I am always interested in clean quality for V1 I am very interested in Gain quality for V2. You have settled that for me. For my combos I use a JJ 803-S in V1 for the full range with lows effect. And now I will use 12AT7s in V2 thanks to your demo. You get a good sound out of that Crate. I never did. But now I realize it was the EL84s that were holding it back.

[@5150powder]

Extremely wrong!!

[@1thess523]

Nice work, to me the Au7 took the fizz off the top but it made it a little darker which I don't really like and that's why I just sold my Blackstar HT 60 because it was too dark for my taste. I have a Marshall JCM 900 High Gain Dual Reverb 50w coming and I saw a review where someone mentioned putting a low noise 12AX7 ACC83 in slot #1 so that's why I am here.

[@neilmcnasty]

I mainly hear volume differences, as I would expect from a tube swap such as this. Tubes are not EQ's. They all sound the same, but has different gain structure. Meaning: The difference comes from the power amp being slammed harder. (This would have become evident if the levels differences was equal: i would yield no sonic/tonal difference at all) I also liked the AU in V2 position best! It had a better level feeding the next stages/power amp. Another way of dealing with the harshness of the highs would be looking for a "bright cap" in the circuit (often found between lug 2 and 3 on the Volume pot) and adjust it, or remove it entirely (like many do on the Bassman circuits), but I do suspect that the unwanted brightness mostly comes from the Power amp section being pushed too hard.

[@liquidsmokemustang1537]

Great comparison. I’d love to see this done on a Peavey 6505+ 112 combo. I do have both tubes and the Peavey LOL.

[@venacorchea]

For sure your video helped me to decide what to do to taming my JVM410H.

[@vasiliymiller]

AX7 - AT7 ______V1____ 1) 0:57 - 1:16 2) 1:11 - 1:30 ______V2____ 1) 1:54 - 2:13 2) 2:08 - 2:27

[@spacesuitor]

_"Oh man...._ _i have no idea what is goin' on right now..."_ -TOWLIE (the towel)

[@abl9087]

Thanks for the comparation. I have the same amp. I have made some mods in the circuit. Capacitors/ Resit. I have also reduce the power to 30w and removing two power tubes to reduce to 15w roughtly. And I have build an resitor attennuator to reduce the volume to play at home.

[@5150powder]

So basically you have just squashed and neutered your amp down to nothing. You got the wrong amp.

[@DMSProduktions]

Yeah, GOOD combo. If the lower valves are a bit scooped, just crank the mid tone control a bit more. Still the overall clip character sounded better!

[@chuckmiller2741]

Thanks for this comparison. I have a crate V18 and it just won’t get clean. I’m going to try 12AT7’s in all 3 positions to see if that helps.

[@jasonoddo7016]

great video mate

[@chuckrichards391]

I always throw JJ 5751's in, they always smooth an amp out. Havent failed me yet.

[@hadleymanmusic]

Ok

[@anthonyb5279]

I hear that a lot. People seem to like those. I have never tried them, they are cheap and I have always opted for Sylvania or RCA. I figured people only use them because they are affordable. I have used Russian Electro-Harmonix 12AX7 when I can't find the good stuff they seem to be less screechy, rolls of on the high end and calms down my AC30. I mean the AC30 has a high cut for a reason. Have you tried a JJ 5751 in a VOX?

[@michaelfern945]

Great video. Very helpful! Thanks

[@anthonyb5279]

Thanks for the comparisons that was done well. BUT I'm sticking with my 12AX7s I do like how they sound. Most of what you are looking for can be done with EQ or different guitars and pickups. I think switching tubes is limiting. Crate Amps are known to be too crunchy, I don't find this to be true with VOX or Marshall. If I ever find my self with a Crate (when Hell freezes) I will revisit this and use a combo that calmed it down a bit. Super video!

[@Wrigglyaudio]

Hehe. Thanks! Ultimately, my solution for this Crate amp was to pull out the speakers, make a 2x12" cab, and use a different amp. 🙂

[@anthonyb5279]

@@Wrigglyaudio HAHAHAHAH!!! Green Backs in those right? Good plan.

[@Wrigglyaudio]

They were Crate Vintage Series. I'm liking them as a cab anyway.

[@Luna25174]

Escuse me do you know if I are any difference between use a tubes with different gain than ones with the same gain??? I bought separately two tubos, But I don’t know if can I use them like this or maybe those can affect my sound quality one is gain A: 94.7 gain B 97.5 and the other is gain A: 104.4 GainB 94.1.

[@bradnelson2637]

Thanks for posting this

[@hadleymanmusic]

Oh god I got a bugera 1990 7 months ago. Its brittle. I jus recieved some 5751's? And some 12 wd7's. Im wondering if I unbalance the phase inverter if it will damage.

[@anthonyb5279]

No it will be fine. You can use some solid state diodes there if you are worried about it, they are more robust. But don't uses them in any other slot they will make a bad clipping tone that sounds like a square wave. I like 12AX7s in my Bugera but I go for the pricy RCA tubes the Russian tubes that come with it suck! They get harsh as they age. I would try better made 12AX7s. My Bugera has a nice tone not at all harsh since I replaced the old tubes that where in it when I got it. Is yours used? Could just be old wore out Russian crap they sound good when they are new but they don't age well you have to replace them more often like every 2 gigs or so. I have had to do that when I can't find RCA.

[@reginjumag7635]

I'm not convinced that there was an actual tube swapping, looks like an emulation to me.

[@JR-to8sn]

Edited: Updated. The biggest difference between these power tubes is the amount of gain they will provide. The 12AX7 has a gain factor of 100, while the 12AT7 has 60. The 12AU7 has the smallest, at just 20. If you're amp was biased to a T or U, then swapping to an X it could have an impact on power supply. A 12AY7 or a 5751 is also a suitable replacement tube for a 12AX7 for lower gain.

[@kenmasuda7696]

JR69 So are you saying that the 12AT7 will damage a guitar amplifier? The folks at Eurotube sold me a couple and said they work fine and sell a lot to tame high gain amps. I have an EVH 5150 50 watt and use them in V1 and V2. I've been using them for 8 months and so far no red plating power tubes and they sound great. Just want to be sure I'm not screwing the amp up. cheers Ken

[@JR-to8sn]

@@kenmasuda7696 No, not at all. I reread what I wrote and edited it, sorry for the confusion. I didn't know what I was saying as I was swapping U, T and X by mistake. If you're amp used and is biased to a 12AX7, then using a "T" or "U" won't have an effect, it's just lower gain and more headroom before breakup.

[@lordgraga]

Great work.

[@cuongnguyenquoc6356]

thank you! Video great nice!.

[@eduardokazuo2900]

Fucking awesome video! The best I found on YT, on this subject, so far! Congrats! Have you ever tried the 5751? Anyways, thanks a cheers from Brazil!

[@jacobbockover1628]

Hmm so no bias adjustment needed?

[@raul_perro]

Preamp tubes has no BIAS adjustment. Only power tubes.

[@mozilla2576]

Thank you. Just the info I was wondering about. Based on the schematic I was looking at....I thought V1 was for the clean channel only?? And V2 was only for the distortion channel?? I guess I need to recheck the schematic. Can you try the last two positions as well?

[@Wrigglyaudio]

Hm. I don't really use the clean channel on this. :-) But I thought V1 is split between channel 1 and 2, V2 is channel 2, V3 is reverb, and V4 is phase inverter. I'm also curious to hear how V3 & V4 affect things. I'll try to get to that at some point.

[@mozilla2576]

@@Wrigglyaudio There has to be revisions at some point....since mine has solid state reverb. V3 in the schematic i found is tone stack...with V1 clean and V2 dirty. ...which is why i was surprised that V1 in your experiment made such a big difference. I see your unit is a black tolex....mine is the white version.

[@mozilla2576]

I looked again....and V1a leads to either V1b or V2(via the channel switch). Then V3 follows V2(as the tone stack for the dirty channel). Both V1b and V3 lead to the PI tube in V4.

[@Wrigglyaudio]

Here's V4: kzbin.info/www/bejne/qXOWgaaIpNqhe8U

[@m6h24]

Au7 sounds scooped mids, at7!is good compromise in v1 but some dont like at7 To me at7 sounds good

[@ajizzle4rizzle]

Now do the EVH 5150ii lbx2 15w-that thing has a nasty hissing sound

[@yogavibe2516]

great vid !

[@texxhexxmm]

Nice Vid! i have a HG+ in V1(ruby 12Ax7)..what would happen if a HG+ Tube is in v2 and a normal in V1 (Ruby 12ax7).. ;) V3 12 AX7 and V4 i use soetimes a 803 S JJ.. Have to find out soon ..

[@canaan_perry]

ATs an AUs are driver tubes. AYs are a better swap for AXs.

[@anthonyb5279]

What he said!

[@yaniv-nos-tubes]

modern tubes are as good as chinese pickups random gain and noise levels bad quality control even robotube can't save the tone

[@anthonyb5279]

NO, you just have to get good ones, old vintage stock is a myth. BUT that cheap Russian crap has NO quality control that I can see. You would think with all the neodymium China has they would make better pickups but no you get Alnico 2 and brass base plates. At least they only cost $10 can't expect much for that.

[@JohnZornAscended]

Not a huge difference.