Tube Rolling for Pre-amps?
I've been listening for a couple of hours to several favorite and familiar CDs now and can say "laid back" and "warm" seem to be the right terms. I can confirm that the highs are less stringent as well. There is nothing that I'm hearing that I don't like but I also can't say that I have a strong preference between them. Two strengths that I would attribute to these tubes: 1) They give a more analog and less clinical feel to digital media. 2) They seem to soften the harshness of overly compressed/loud CDs. This may be they biggest appeal to me. Al, I'm not going to put the silicone rings on the Amperex tubes. They are fairly hard to get off the old ones as is. |
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! |
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. |
Okay, I couldn't wait. Got them installed in the V1 and V2 positions. I can tell a difference immediately. The first thought in my head was "laid back". Maybe this is what people mean by 'warm'. And this might be impossible but the music sounds a little slower. Not so much a tempo issue, almost like a slower pace. Can't really describe it. I think the highs are tempered a bit and a little less bright than the original tubes, which might be a good thing. Certainly less clinical than the original tubes. The effect on bass is interesting. It seems a little deeper but does not seem to have lost any tightness or precision, or at least not much. That's all I can say right now. Will obviously let them play for a few hours and then put the old tubes back in for another comparison. For the record, the original tubes are Electro-Harmonix. They say "Made in Russia" and below that "04 02". 6922H is printed near the top. Pins are silver in color. Each one has two rubber rings up near the top. Thanks again to rodman99999 for the opportunity to give these a try. |
@rodman99999 : The tubes are here and they do look pristine. Testing begins now. Right now I'm listening to the CD I will use for a reference with the original tubes. Couple of questions: Obviously I will unplug the unit before opening it but how long do I need to let it cool down before changing tubes? The original tubes appear to have some sort of rubber ring around the outside of them. Does this stay with them or do they get removed and put on the new tubes? Will let you know what I think once I've had a few listens. Will also get my wife to listen as well and see what she thinks. She is not an audiophile but she is a musician.....and sometimes 'naive'' ears will be more sensitive since they have no expectations. |
@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). |
Interesting that many of the concerns being expressed regarding tubes/tube rolling are addressed with the PrimaLuna Dialogue Premium preamp. How do I know if a tube is failing? The PL preamp has LED indicators that indicate a weak or failing tube and the protection circuitry that shuts down the preamp to protect it. What about biasing newly rolled tubes? The PL preamp has audio biasing circuits that eliminate the need to manually adjust bias. Contaminating tubes by handling them? The PL preamp comes with a set of white gloves for handling tubes. Damage to tube sockets from tube rolling? The PL preamp uses high quality ceramic sockets that are bolted to the heat sink chassis and hand wired forming a connection that is structurally superior to the more standard practice of having the sockets wave soldered to a PC board. Not trying to sound like a commercial for PL but hey....just sayin' J.Chip |
@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". |
@rodman99999 I also had a pair of 6922's; one JAN and one USN matched. Later I upgraded to a pair of Amperex 7308 PQ USA, $400 pair, all from Brent Jesse. The 7308 have the same liquid sonics, but with awesome bass impact. Mine are matched 1960 & 63. These Amperex (and Philips) are so rare that different years must be tested to find a matched pair. |
" 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! |
"I’ve had good luck on E-Bay, but I’ve heard horror stories also." Horror story for me - got curious to try something new after listening to Mullard 2492s. So bought some Amperex Bugle Boys on ebay that fried my pre’s power supply as soon as I powered it up. Ebay seller refunded my purchase but repair was my problem. Between shipping back and forth to the only guy in the U.S. who does repairs on Symphonic Line and parts/labor, it set me back $600. Eventually bought Telefunken E88CC’s from Kevin Deal to satisfy my urge to explore upon his recommendation, and they’ve been in for the past 5 years. One tube went wonky a month after I bought them and was replaced gratis, and another one went weird about three years ago so bought a replacement. Neither tube claimed any additional victims. I don’t know about lasting 10,000 hours, but they must have 5,000 hours on them and still sound fine. |
@n80, as far as pricing, these tubes are $200+ for 1960s NOS. They are premium military grade, made in USA, with white lettering (orange lettering cost less). Low noise and should last for years. Just to give you an idea of pricing when you shop for a 2nd pair: Brent Jessee offers... E88CC / 6922 Amperex white PQ type, white label, USA made, gold pins.MATCHED PAIRS. $230. The PQ version has the same sonics as the Amperex JAN. 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. A very generous offer by Rodman. |
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 : I have. Can't wait to give it a try. Already looking for 2 more of those tubes just in case I really like them and want to have all 4 the same. I've run into a couple of things though. One source says these were counterfeited for a while. I see them on reputable sites for $150 - $200 each. I see them in pairs on eBay for $150. See some individuals on eBay for $45. Just guessing the eBay offerings are probably not the way to go. |
@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! |
Was it Kevin, that mentioned having all four of your LS-16’s tubes matched? If so- did he elaborate? Just curious(he does know his stuff). No, he never said anything about the LS16. That's just my opinion, just like your opinion on mixing and matching. I think, that on this preamp, it's not a good idea, but again, it's just my opinion. I was only an ARC dealer for many years and have owned almost all the preamps that they have made, but, again, this is my experience only. Some of the older tube preamps benefited greatly from mixing and matching, so it really depends on the circuit. @n80...Nothing wrong with trying, just don't drive yourself crazy. Yes, it can and will happen :-) |
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. |
I also have some deoxidizing spray that I used to clean and repair the pots on my old receiver. Should I apply this to the pins? I have always been told not to do this. I tried something many years ago and it ruined not only the tubes, but the tube sockets had to be replaced. I don't remember what it was, (might have been "TWEEK"). I'm sure others have had different results... |
The tubes that the LS16 uses are 9 pin. Once you turn the tube over, you will see that there are in a circle pattern with a gap between. Align that gap with the gap in the tube socket and push down firmly until it seats. I usually will put in and pull out a tube several times to make sure that if there was any residue on the pins, it gets scraped off with a few rotations. I wear gloves, I was always told that the oil from your fingers will make the tube burn uneven, but Kevin Deal, (probably knows more about tubes than anyone I've meet), says that's bunk. I still wear them. You do not normally bias a preamp tube. So no worries. This is me, but I would always replace all (4) tubes at one time and all need to be the same. Yes, there are exceptions, but mixing tubes in this matter, often leads to poor performance. (I am talking about the OP's ARC LS16 preamp and nothing else because I know that it can vary widely, but this pertains to the LS16). So yes, get the tubes as close to each other as possible. |
@mofimadness : Very nice indeed. I am often taken aback by the kindness of folks I don't even know. I hope to be able to pass on such kindness in the future. Now I am a little worried about whether I will hear a difference or not as I don't have a lot of confidence in my ears. I will have my wife listen with me. @rodman99999 : I have PM'd you my address. Now that I'm actually going to get to try tube rolling I have some questions: Access to the internal of my LS-16 is easy. Just a few screws. I'm assuming the removing and replacing these types of tubes is just a straightforward firm pull up to remove and firm downward pressure to install.....no twisting or locking? Wear gloves to keep oil, etc off the tubes? When I Google tube changing the issue of biasing comes up, mostly with guitar amps. Is this something I need to worry about with my pre-amp? The manual does not say anything about that. My pre-amp uses four tubes. Someone said above that I should be able to tell some difference with just two but I'm not sure where to put the two replacement tubes. The layout is like this: V1 V2 V3 V4 Apparently when new the tubes are actually marked V1-V4 for exact location. If I hear a difference with two will that difference by more pronounced with a full set of four? If I like what I hear with two of these tubes and decide to get two more how precisely do they second two need to be matched with the first two? Is it okay to buy the same brand and designation or will they all four need to be tested and matched? Sorry for questions that might seem obvious but this is new to me. George |
rodman99999....that's very nice of you! Those are very decent tubes, so @n80 should hear an improvement with those. I love this community! |
@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. |
