@HeadphoneNoob , welcome to the mysterious and very confusing world of tube rolling. I just started down this path myself, and the 12au7 happens to be one of the tubes I’m rolling.
Here are some things that I’ve learned over the last few weeks:
- A high price may just mean the tube is rare, it doesn’t necessarily mean that it is better sounding than a cheaper alternative.
- Many manufacturers made tubes for someone else, and those tubes can be a lot cheaper than their own brand, despite being made in the same factory. I’ve no idea if they are the exact same tube, but you will at least get a similar sound, at a much lower price, e.g. Brent Jessee sold me a Philips tube made by Mullard as the cheapest way to try out a Mullard. I’ve also had some success with Baldwin tubes, made by either Sylvania or Raytheon, which are very cheap. YMMV but those Baldwins are cheap enough to try out.
- The tube will take time to burn in, which means the sound may change. The Mullard I mention below sounded very bass-heavy when I first tried it, and it took a few hours for the sound to balance out.
- Just because a tube name has many of the same letters, it could be very different, so double check with the amp manufacturer when in doubt, e.g. the 12au7, 12ax7 and 12at7 are different tubes and are not necessarily compatible. In my case, my 2 tube amps were built for a 12ax7 but Justin said it was OK to use a 12au7 or 12at7. If you don’t get that “permission” from the amp manufacturer, then unless you are an expert, stick to the US and European equivalents of the amp-required tube (e.g. 12AU7, ECC82 and a couple of others that say “this is the same as a 12au7” on the Brent Jessee 12au7 page in your case).
The biggest problem I’ve found researching tubes is that you’ll find a lot of people saying “this is great” or “I hated this” but they never give you the context:
- What equipment are they using?
- What other tubes are being used in the same chain?
- What’s the sound profile of their baseline. And what did the tube add or subtract from that?
- What sound profile do they prefer?
- What kind of music do they normally listen to.
For instance, I was just trying out a Mullard 12au7 a couple of days ago, and it really emphasized the bass and mids but the highs seemed a little rolled off. Vocals and reggae sounded awesome, but indie rock sounded a little too smooth, and didn’t have the bite I was looking for. Now I had done enough research that I was expecting something like this, and I wanted to hear it for myself, but I’ve read too many posts on various forums that just state something like “Mullard is the best”, which is misleading.
I’ve had a lot of help from 2 vendors:
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Brent Jessee, which @bpcarb already pointed you to. His website can be very overwhelming to a newbie tube roller, but the site is very good at pointing out bargains, especially where a particular manufacturer made tubes for someone else. Brent is also very good at getting back to you, and he told me he prefers email.
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Vintage Tube Services. The owner, Andy, is the opposite of Brent. He doesn’t like email, so call him if you want his advice. @bpcarb and others have had issues trying to get through to him, so apparently I’ve been very lucky that I’ve been able to connect, and in fact he even called me a couple of days ago. If you get a busy signal, just keep dialing until you get through, don’t leave a message. Once you talk to him, he’ll spend as much time as you want, answering your questions. I found him down to earth, and he talked me out of expensive tubes and steered me to some cheaper ones, which he thought were just as good.
And finally, I can’t vouch for this, but I found this matrix on the Steve Hoffman forum.
