Four Different Tubes - One vintage Neumann U67 

Quick timestamps for jumping back and forth: Mono guitar - 1:32 - 1:43 - 1:53 - 2:03 Stereo guitar - 2:18 - 2:28 - 2:38 - 2:48 With vocals - 2:58 - 3:08 - 3:18 - 3:29

Great video! I have swapped a couple of tubes in my re-issue U67 mics but after seeing this I tried the Mullard EF86 tubes which made a HUGE improvement over the stock Russian EF86. I had tried NOS Telefunken EF86 and EF806S tubes as well as JJ electronics which were all OK, but the Mullard tubes sound the best. Thank you for making these videos, they are a fantastic resource!

I like the Mullard on guitar and the Valvo on vocals. Nice Comparision, thanks for that.

That Valvo is gorgeous

Tubes in certain microphones can make a huge difference. The U67 is particularly known for it's sensitivity to different tubes. Personally I love an Amperex EF86 in my custom MK U67.

Great test, I ‘m with you and the Mullard! For tests like these you could record the track and then use the Mike to listen to your monitors. That way, the source sound and signal chain are identical only the tube changes . Thank you!

Great comparison, I had come to the same results myself that I did listing to this comparison in that the top end is slightly airier with the Telefunken tubes, though I prefer the Telefunken EF86 to the others.

Fascinating, thanks for the comparison. The Telefunken stood out to me as well. On first listen, it seemed very well-behaved; perfectly smooth low-mids, polite high-mids, and a soft top-end that could be brought to life with a bit of eq. But unfortunately it just doesn't take eq as well as the others. Its lack of saturation in the top-end makes it sound dull by comparison, no matter how much you boost it. That said, I can imagine it pairing beautifully with an old-school valve preamp. The others all have noticeable resonances and/or dips; but take eq very well, and are easily evened-out. They also add a gorgeous sparkle to the high end. Exactly what want from vintage high-end valve equipment. The Valvo almost has an AKG vibe to it (softer mids, more prominent top-end), which nicely balances-out the classic Neumann strong mids. Really nice pairing.

Hi Christian the VALO win this shoot out, it's so nice in the bottom end without any muddiness. But if you did want a bit more distinction / clarity on the guitar, maybe the Mullard EF 86. But your video proved the TUBE does affect the sound. Great stuff

Great vid as always. Is it possible to do the same kind of video with vocals only? I find tubes fascinating.

Telefunken sounds the most balanced. Mullard a little bit more upfront and less bass (as usual with this brand) and the Valvo brought some weird resonances. RFT something between Telly and Valvo.

Great test Christian. I listened last night on my earpods but Downloaded the tracks and listened on my monitors this morning and feel different about some things. On acoustics I personally really like Tele, I like that mid push, not too much bass, not too much high end and it nicely compresses the transients, it sounds how I usually end up mixing acoustics. Overall ,on my monitors I'm liking the Valvo, on earpods there was something super flattering about the Mullard but it might be a bit too much, the transients are much sharper on the acoustics, the Valvo seems to be kind of a happy middle ground. And side note, though it's obviously never going to be a perfectly scientific comparison, the differences are consistant, the Tele always sounds like the Tele on the 3 takes and so on and so on.

I liked the mullard !

Agree that the Mullard was best! The other 2 EF86s had odd resonances jumping out. I think the Telefunken would be great with a little EQ as well.

The Mullard sounds also best to me. This Tube to me has an even sound.

Valvo for the win

Truly supervised there is even an audible difference! But I still prefer my cheap and fresh Shuguang valves.

Thank you Christian! But it's impossible to make a scientific test with one mic and different tubes. When I have tested rme ufx ii and apollo 8p I have faced with different angles and dustances from guitar to microphone. It was huge difference on the same audio interface. So... It is not working like this IMHO

Could these tubes be used in a preamp unit or just the mic

Does not work the same for all tube mics. Depending on the topology the tubes are used. In some cases it does not make almost any difference.

You said you used a Neumann U67 for the test, but the picture on the screen is a Telefunken. What on earth did you use?

RFT, VALVO, TELE,.......Mullard dead last for me

I was able to hear the differences, but found them kinda musically irrelevant, a preamp is more musically relevant although kinda equally subtle in sonic character shift. Also, just hearing any subtle change is nice, because of variety, so that can also trick oneself to feeling it does more difference than it actually should?