Output tubes can change the character of the sound and frequency distribution, e.g., more bass. Rectifier can treemendously add to clarity, punch, and dynamics of sound. Inputs can be both.
Jerry
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If the rectifier is doing 100% of the job, it shouldn’t have much impact on sound. Sort of a big if in the real world. There can be a bit of sag when the amp gets pushed hard with rectifier tubes, which can be a desirable thing for guitar amps, but not so much for hi-fi. As long as in-rush current doesn’t pose a problem in a given circuit, solid state rectification can be a great way to accomplish that task. There are always a bunch of variables in play, but IME output tubes have made the most significant differences, but I’ve also heard ample differences in the drive tubes, so don’t want to dismiss the value of exploring that avenue too (tends to be a cheaper approach!). If you have a tube preamp, those tubes can make a pretty audible difference too. Because every circuit can use different values, and different brand components in support of a given circuit for the same tube type, every tube is likely to sound different if placed into a different amp. There’s also a lot subjective preference involved too, so ultimately, other’s opinions may give you some direction, but you still need to experiment and draw your own conclusions. With that said, I’ve pretty much settled on RCA clear top 12AU7s as phase splitters, and Sylvania 12BH7a as a center voltage driver for my Dyna/VTA 70 amps. I’m currently running Tung-Sol 7581A outputs, but have also really enjoyed the Gold Lion KT66s. Prior to that I found the EH EL34s to be a great bang for the buck with good mids, and the Nesstone 6CA7 to have more solid bass. Have liked JJ ECC803S in my preamp, but like the Mullard CV4004 better. YMMV (more likely YMWV!) My audio budget has historically been miniscule compared to some, but I was fortunate enough to re-tube and experiment quite a bit in the year or two prior to Russia invading the Ukraine. Tube prices have more than doubled in most cases since then. If you’ve got ample budget to play, have at it. If you need to be more miserly, I’d suggest doing preamp (if it applies) and driver tubes first.
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Never used a 7591, but I’m pretty sure it’s a different tube altogether with different pin wiring, and not interchangeable with a 7581. The 7581A is the higher output version....KT66 and 6L6 are interchangeable with it AFAIK, but always check your owners manual. In my case, the TS7581A was a replacement to a very nice sounding GL KT66. They’re approaching 30 hours now, and I’m having little urge to go back to the KT66 at the moment. |
On my tube amps, I've always gotten the most noticeable changes rolling the input gain tubes. Power tubes basically boost whatever is fed to them, but they do have their own voice as well and can also bring some change, most usually in the lower range and sometimes in midrange warmth. In the long run, it's more economical to stick to rolling the small tubes. My rolling MO is to find a power tube I like that is readily available since they consume themselves at a more rapid pace. Current manufacture Tung-Sol's are my go to choice in that regard I do the same with the small tubes, my reasoning being that I would hate to fall in love with a rare NOS tube and then have to switch to something else because it was too hard or impossible to get future replacements. The best NOS small tubes never get cheaper because there are less of them available as each year passes. The up side is that, depending on how they are driven, they can last upwards of 10,000 hours. Tube rolling is fun, but it can also be an expensive pain in the keister. A tube amp that offers switching between triode and ultra-linear gives you an additional choice for sound treatment with the same tubes, and IMO, it's a must have. |
Having just changed out the line stage tubes on my McIntosh C2200, I would strongly recommend that you contact Brent Jessee (audiotubes.com) for his expertise and suggestions based on your needs. I wish I had contacted him years ago as the difference changing out the tubes to those he suggested has made an incredible difference, and at a very modest price. |
My experience with vintage gear is that a bad/cheap rectifier tube can cause problems/bad sound, but a good one just makes the system work correctly (i.e. it doesn't enhance the sound quality). Power tubes, on the other hand, will have a significant impact on your system's sound signature (different tube types will boost/diminish bass response, while different tube brands/qualities will change the clarity and tonal response). Again, this is my limited experience with a 1950s amp. Oh! and I definitely agree that the biggest enhancement in overall sound quality comes from rolling the input gain stage tubes!! |
desingnsfx, As others have suggested, when in doubt, reach out to Brent Jessee.....he is simply the best resource for information and tubes. Tube rolling power tubes is a no go for me, as I have 4 output tubes, I currently have Tung Sol KT88s and KT120s. Rectifiers do make a difference, my Philips 5R4GYS tubes are better than my Mullard GZ37s, which are better yet than the more common Sylvania and RCA rectifiers (some of which can be quite good). The Philips used to be affordable, but believe they're about $250 each now Signal tubes. Not sure which you use, but I've never been disappointed in any NOS Amperex tubes.....Brent also has the best reference material I've ever seen on old 12AU7, 12AT7, 12AX7, 6SL7, and 6DJ8 style signal tubes.....just click on your style of tube in the yellow box Best of luck
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In my experience both to a similar degree but in slightly different ways!!! I have recently been rolling tubes in my Supratek preamp. It takes 1 rectifier in the power supply and 2-6l6 output and 2-6sn7 input/driver. Changing my rectifiers I noticed more detail and punch with my best tube a Mullard GZ34, next best is my RCA 5AS4A ST bottle which has more warmth, fullness, more laid back. Other 5U4GB and 5AR4 from Sylvania, Tung Sol, GE, Sovtek, Reflector, RCA were fine performers but just missing a little something. Output tubes I could hear subtlety more bass punch, dynamics, clarity and details in highs, soundstage refinement. Not big just slight differences comparing RCA 6L6GB ‘60 blackplates, NOS Russian CP3S, CP3S-E, Svetlana 6L6GC, Shuguang military ‘70’s 6L6GC. The biggest differences by far were changing the input/driver 6SN7’s many to choose from. Fyi- that Phillips 5R4GYS is next to impossible to find and they go for $300-400 per tube. Only one on ebay in Asia (Thailand?) for $320. Russian output tubes from ‘60-70’s sound amazing and are bargains if you are willing to buy from Ukraine etc. Good luck with it all. |
@designsfx yes I have ordered from a few ebay sources and all went well with the exception of one unusual seller behavior. It takes a good 3 weeks to get delivery. Also, testing, used quality and pictures matching can be a risk but I have had good luck so far. Examples: Ordered new and they used but good testing. Testing can vary but testers are all very different and I have not felt they were being dishonest. I only order tubes with actual pictures and test results. It is somewhat of a crap shoot but worth it in my mind. Some fantastic tubes can be acquired for a song. I look at it as helping them out during a terrible war. |