OOPS! Looks like I missed a post. Couldn’t wait, HUH? No surprise! I think I mentioned, in the note I enclosed, they might sound strange, before they’ve been played for a few hours, having been in a drawer for seventeen years. I don’t think the EH tubes were from the factory, but then- I can’t swear to anything ARC’s done, since the early 90’s. They were using Sovteks, back then. I always thought EH tubes kinda zingy, but- that’s just my opinion and you know what they say about those! Your welcome/have fun!
Tube Rolling for Pre-amps?
I have an Audio Research LS-16 that feeds a Madrigal Proceed HPA2 solid state amp.
I did not choose this equipment; it was given to me. From what I can tell the original owner spent a good bit of time matching up these two components with the speakers, Aerial Acoustics 7Bs.
The tubes in the AR are original. Probably 10-15 years old? But with an extended period of not being used.
The system sounds good to me. I don't need to change anything.
However, I've been told that the tubes are old and may need to be replaced soon. I've also read a little bit about tube rolling but most of the articles I've seen talk mostly about tube rolling with amps and not pre-amps.
So I have some questions:
1) If the original owner wanted a system that sounded like a 'tube' system, why not have a tube amp and pre-amp? Does it make sense to have a tube pre but SS amp?
2) Other than outright failure, how will I know if my tubes _need_ to be replaced?
3) With a SS amp, will changing tubes in the pre-amp have a noticeable impact on SQ? In other words, is tube rolling for a pre-amp played through a SS amp a thing?
4) For someone like myself who is happy with the system and who is also easily frustrated by A/B testing is tube rolling the pre-amp even worthwhile? I can almost always hear a change when comparing various components but only rarely am able to say A is better or worse than B.
( I probably can't even articulate effectively what I look for in terms of SQ except that I like the bass to be tight, precise, well defined and not boomy. I do not like the music to be overly bright or tinny. I like depth and lushness but not overly warm. Not sure if these are things you alter with tubes.)
Thanks for any advice.
I did not choose this equipment; it was given to me. From what I can tell the original owner spent a good bit of time matching up these two components with the speakers, Aerial Acoustics 7Bs.
The tubes in the AR are original. Probably 10-15 years old? But with an extended period of not being used.
The system sounds good to me. I don't need to change anything.
However, I've been told that the tubes are old and may need to be replaced soon. I've also read a little bit about tube rolling but most of the articles I've seen talk mostly about tube rolling with amps and not pre-amps.
So I have some questions:
1) If the original owner wanted a system that sounded like a 'tube' system, why not have a tube amp and pre-amp? Does it make sense to have a tube pre but SS amp?
2) Other than outright failure, how will I know if my tubes _need_ to be replaced?
3) With a SS amp, will changing tubes in the pre-amp have a noticeable impact on SQ? In other words, is tube rolling for a pre-amp played through a SS amp a thing?
4) For someone like myself who is happy with the system and who is also easily frustrated by A/B testing is tube rolling the pre-amp even worthwhile? I can almost always hear a change when comparing various components but only rarely am able to say A is better or worse than B.
( I probably can't even articulate effectively what I look for in terms of SQ except that I like the bass to be tight, precise, well defined and not boomy. I do not like the music to be overly bright or tinny. I like depth and lushness but not overly warm. Not sure if these are things you alter with tubes.)
Thanks for any advice.
Showing 19 responses by rodman99999
Five or ten minutes will do. Be very careful, not to touch ANYTHING inside the unit, BUT one tube’s glass envelope. It’s a pre-amp, but there may still be some serious voltages, waiting to awaken you. The rings are dampers(probably Silicone) and you can try them on the Amperex. They'll probably take some of the print, off the tube(not a biggy). You might try waiting until you’ve listened to the Amperex for a couple days, without them. See if you hear a difference. Take your time, relax and have fun. |
@jchiappinelli- I live in the state of confusionI(Stunadia). Have to check myself and my, "facts" constantly. Senior moments/brain farts, seem to be increasing in frequency(Old-Timers Disease, I suppose). PrimaLuna has done much, to take the pain out of tube audio. Particularly, in their power amps. I’m also a big fan of(mostly) P to P wiring, the use of quality parts, extended tube life and the flexibility they offer, in choosing output valves. |
@ jchiappinelli - I’ve yet to see a tubed pre-amp, that requires it’s tubes’ biases to be adjusted, when they’re changed/installed. Not saying, one may not exist. Biasing is always required for power output tubes, whether done automatically, or- manually(fixed bias). The PrimaLuna Premium integrateds and HP power amps have LEDs to indicate bias balance, and tube failure, for their Adaptive Autobiased power output tubes. Where are the LEDs located, that indicate tube failure, on the DiaLogue Premium pre-amp chassis? Where does PrimaLuna mention, "auto-biasing circuits", regarding it’s preamps? I’m just curious. From the PrimaLuna preamp manual, "Further, every time you insert a tube, you stand a chance of loosening the tube sockets. It’s okay to have fun, and we support that, but don’t go crazy and swap tubes in and out twenty times in a day."(No one’s sockets are bulletproof). |
@n80- "I probably should not be pre-loading expectations either!" I haven’t mentioned anything, regarding attributes to be expected/anticipated, for that reason. I’m fairly certain, you and your wife will notice what the tubes deliver, without prompting/suggestion. Particularly, if your pre-amp, is still equipped with it’s original tube compliment(perhaps, Sovteks?). Take your time and listen to your favorite/most familiar cuts, for anything, "new". |
" You may see a pair with one JAN tube matched with a JAN USN. They are the same tube, the USN was sold to the US Navy and are very rare nowadays." Mine are marked for Joint Army Navy(JAN-CEP) and NAVY (6922) contracts, from ’62’ and ’64. They were last tried(taste tested) in my BAT VK-D5(a $4500 investment, then), without incident. I’ve no doubt, shorted tubes could cause all sorts of havoc, depending on the circuit design/protection. These aren’t. They weren’t nearly as salty, 17 years ago, either(maybe half the current cost). They’re on their way! |
ALRIGHTY, THEN! They'll be on their way, tomorrow. If you like the sound of them, and you're serious, regarding another pair; these(below) are identical. When you get my pair, compare them to the pics in this ad
(better pics, than the eBay ad)
. ie: The halo getter, the getter support structure, the grey plates and shields, molded creases on top of envelope, gold pins, early Sixties date codes, etc. https://www.tubemonger.com/1961_62_Amperex_USA_6922_E88CC_Gold_Pin_USA_NOS_p/1226.htm |
@mofimadness - OK(thanks for that). Owned an SP-9 and an SP-11, which were both a ton of fun, to tweak, in various ways. My son wound up with the 9. Never had heard that, regarding the 16 and wanted to be certain, I wasn’t missing something. It’ll be interesting/informative, when we get n80’s input(I hate the word, "feedback"). Happy listening! |
There’s no need to match all four, only two between channels(ie: V1 closely performance/readings matched to V2 and V3 needs to match V4). Nor do tube manufacturers need to be the same, between V1/2 and V3/4. ie: If you like the warmth/sound of whatever two tubes you’ve installed(ie: say these Amperex, in V 1/2), and don’t want any more warmth, you’d want to find a tube that adds no more warmth, or- just leave the original pair alone(in V 3/4). When there are multiple tubes, in the same circuit/channel, it’s common experience, that using different tubes will reinforce the better qualities of each tube and minimize the weaknesses. I’ve not heard of the LS-16’s circuit responding differently(personally). Gold does not oxidize and I’d appreciate it, if these pristine gold tube pins weren’t repeatedly pulled in and out of a socket. Installing them, in either the two positions/sockets closest the rear, or the two closest the front of the unit, should tell you what you need to know. A two-fingertip grip, as close to the base of the tube as possible, pulling straight up and two at the top, pushing straight down, has always worked for me(no bent pins or widened sockets). A cotton glove or sock(pulled over the hand), would be nice/can’t hurt(it’s what I do). I’ll have them on their way to you, tomorrow. |
@n80- You got me thinking about my tube inventory. I found a NOS pair of these(the exact same vintage/iteration tubes as in the description, except- the printing on mine is still perfect): https://www.ebay.com/itm/E88CC-6922-AMPEREX-N-Y-USA-GOLD-PIN-TUBES-JAN-USN-MATCHED-PAIR-1960s-MDGGZ/... If you like, I’ll send them(gratus) and you can experiment. They were a tad too warm(for my tastes), when I tried them(maybe 17 years ago). Even if you don’t care for the sound, it should let you know how much impact tube rolling can have. |
Yes- Only changing two tubes(either V1 & 2, or V3 & 4) will generally provide you with a good slice of what can be expected, if all are swapped. I’ve avoided counterfeits and junk, by only purchasing from reputable tube mongers. ie(for nine pin miniatures): Brent Jesse, Tube Depot, or this guy from whom I’ve purchased the most: https://www.ebay.com/sch/audiotubes_de/m.html?_nkw=&_armrs=1&_ipg=&_from= Upscale only refuses to sell their NOS tubes, for use in pro audio equipment. They have lots of NOS 6DJ8 types, for home audio. I found everything that Siemens made, after the early/mid 60s, grey shield CCa, a bit too zingy/bright for my tastes, but- that could just be the rest of my system, ears or preference. I only said what I did, about live music, because after extended listening in good, live venues- one sometimes gets spoiled(perhaps, educated) and the average home audio system MAY then sound, "broken". |
Tubes don’t get old/weak, from age(only use), unless they have a vacuum leak. If you’re really concerned about the remaining life of your 6922s(assuming yours isn’t the MkII), you might send them to theses guys, for testing: http://tctubes.com/tube-testing-service.aspx I’ve found them accurate, honest and reliable. Regarding your last question, YES- the presentation you’ve described, can be adjusted with the preamp tubes. Any good power amp, will faithfully pass whatever signal it’s fed, so- make it the best you can. ie: NOS Amperex(a little warmer than stock ARC tubes), NOS Mullards(a lot warmer than stock), NOS Siemens(tighter bottom, airier and more detailed/cleaner than stock). There’s no problem, trying just one pair per gain stage, at a time, to see if you like the change. I rolled tubes through a couple different ARC pres, never trying anything but E88CC/7308 (or better) iterations, with gold pins. I settled on the early Sixties, grey shield, Siemens CCa. I’ve six in my CDP, now(glad I bought extras, way back when). Good information, here: http://www.audiotubes.com/6dj8.htm Then again- IF you’re actually happy with your sound, why fix something that isn’t broken? Just don’t go listening to a lot of live music. |