Tube Rolling in the Line Magnetic 508/805

There's an excellent thread that covers a lot of bases going about this fantastic amp. But I'd like this thread to focus strictly on tube rolling.

What have you tried that has yielded improvement?

 

6SL7, 6SN7, 300B, 805. In that order of most to least improvement, in my case.

My current compliment is ; Mullard ECC35 (6SL7), Tung-Sol 6SN7 Round Plates, EML 300B-XLS, and NOS RCA 805.

To be fair, prior to the RCAs, I had Psvane 805 A-Ts before the RCAs replaced them. The reason was one of the stock tubes' bias was drifting wildly and the previous owner replaced the pair with that upgrade. In contrast, I don't find the RCAs to be that much better but I do trust their QC far more than I do today's Chinese tube manufacturers.

According to my tech, they measure at least 3x higher than the Psvane so there's a good chance they'll last much longer while providing more dynamics.

 

I keep reading that the RCA red bottoms are great too

 

I think people should be clear on whether they have the 508 or the 805 because it seems like people have different experiences.

I've only rolled the 6SL7 and 6SN7 in my LM805IA and I think the 6SN7s have made the most difference in my setup. Currently, I have an RCA Red Bottom 5961 (6SL7) and some Sylvania 6SN7GTs in the 6SN7 slots. Next up will be the 300Bs.

 

In my experience 6SN7s can sound clean or have minor distortion. Russian 1578 or Sylvania 6SN7GTA are good ultra clear sounding tubes. As for a 6SL7, I suggest RCA 5691 or Tung Sol 6SL7.

 

@Steve Hoffman Can you recommend a 6SL7 and a 6SN7?

 

They are warm but they feel artificially so. And they are not very detail oriented so you lose some musical information. They do sound euphonic so that might be pleasant to some but if you have superior tubes available to swap, you'll appreciate the difference immediately. I find them to also have a strange quality in making bad recordings sound a bit less so but also hold back well-recorded music, kind of like a musical prozac of some sort.

In the end, it's all about synergy. Since everyone's rig and tastes are different, what sounds good in mine might not in yours and vice-versa. Every tube I tried has someone in the long thread for the 508IA swearing by it so...

These are the ones I've tried in this amp ;

Tung-Sol 6SU7GTY : lots of detail, very musical, forward-sounding, etched in high-end frequencies which eventually caused me to have ear fatigue.

RCA Red Base 5691 : warm (though it feels forced, somehow), inviting, loss of details in the mids, velvety low-end with very little detail, slightly rolled off high-end, euphonic, pleasant sounding but too many setbacks for me to keep. Kind of an old-school sound.

Mullard ECC35 : warm, inviting, low-end with slam, good detail (though a tad less than the 6SU7GTY), made my amp come alive, good (but not great) high-end extension.

And of course, the stock tube. I believe it's an Electro Harmonix. They've never made a single tube I liked. Every one of them sounds dreadful. Anyone who doesn't upgrade the tubes in these amps is seriously holding this amp back as it's capable of so much more.

 

Thanks for the info. So what did you stick with? Mullard? I'm not a tube rolling guy. I want to get the right (for me) tubes and move on

 

All depends on your tastes and rig, my friend.

If you have timid and dull-sounding speakers, the Tung-Sol 6SU7GTY would be right for you. If your speakers are forward-sounding and hype detail to a ridiculous degree, the RCA might be OK for you. If you find your setup doesn't sound the warmest and is a bit bass-shy, don't want to recede or hype the presentation, the Mullard is for you.

FWIW, the Mullard is the one that's had the most favorable reviews in the long thread... and IMHO, it's no wonder why. Literally is a night-&-day difference in my experience! Switched it back to the stock tube for a few minutes a couple of months ago and sure enough, same HUGE difference. I checked your profile and see you have the Chinook which I owned for a bit. It is a more neutral-sounding phono preamp and not necessarily the warmest or bass-happy preamp there is so the Mullard is likely the best fit for you.