I recently replaced the tubes in my sp16 after about two years of fairly heavy use.
In my case, the issues I noticed with age was noticeable background noise that was not there prior.
I replaced all 6 tubes with Groove Tube Gold 12AX7s from Guitar Center for $20 each.
I decided to try to buy from the GC down the road first before going to ARC for their "certified" tubes at higher cost.
The olny difference I notice in sound is a tad more background noise in the phono section than prior perhaps, but nothing significant. The sp16 is very quiet now as it was with the new tubes that came in the unit from ARC when I bought it.
I figured if these did not work out, I would buy then from ARC and keep these as spares, but things have in fact worked out well.
One thing I found out of value is that rearranging the tubes internally can have effects on the amount of background noise produced. The trick is to get the best/strongest tubes into the prime slots I believe either by trial and error as I did or perhaps using a tube tester. I was able to prolong the useful life of my original tubes by almost a year doing this.
I always buy a new tube set when I get a new piece of equipment. Worst case, (outside of spending extra money) is I then have a spare set which is very useful, especially in diagnosing quickly if I have a tube problem or something else has gone wrong. Normally I do not buy new tubes from the manufacturer. Not only are they generally overpriced, but they are generally new production only because the company has to keep a large stock of known quality tubes on hand. The bigger the company the bigger this consideration.
I suggest you are doing the right thing posting on the internet for advice. Keep reading until you have the names of the handful of reliable suppliers of NOS and speciality tubes to Audiogon and Audio Asylum members.
One of the problems with tubes is once your start "thinking" that it might be time to change the tubes, your doomed, you might as well change them out because in the back of your mind, you will be always questioning the tube's performance, even if they are 100% good.
Something VERY important, when purchasing preamp tubes; being CERTAIN they are CERTIFIED LOW NOISE. ie: Upscale Audio stringently tests and grades their tubes, per their noise, microphony, and triode balance(VERY dependable). ie: (http://www.upscaleaudio.com/tubes/12ax7/ge-12ax7.html)
Some of the NOS Mullard, Telefunken, and other tubes seem to keep on going in some gear, 10 years plus, only a couple of years in other. I'm talking high hour daily use also. Usually with the good NOS ones, as long as they test good, their sound doesn't seem to deteriorate. If you plan on staying with tubes, I would consider buying a Mutual Conductance tube tester. All of the tube amp people I know have extra tubes on hand. The quality of some of the newer ones are getting better, but I don't think they've reached what some NOS ones can do. Others say they've have it down now, for sonics and reliability.
It's not easy getting a quiet reliable tube.
Thank you kindly for the responses. In addition to Upscale Audio, which other manufacturers have a first-rate reputation for tube quality?
Allow me to rephrase the above question. Since Upscale Audio is a seller (not a manufacturer), which particular brands of tubes have a first-rate reputation for low noise & sonic quality? Thank you!
I would check with ARC but I believe it's every 5-6000 hrs. Distortion does go up as the tube ages and sometimes it happens so slowly you don't realize it until you replace them.
Antique Electronic supply
Amperex, or their Bugle Boy is excellent IMO. But, I can't say how they will do in your ARC preamp.
Siemens and Telefunken, for tubes that are known for transparency/freq extension. Mullard and Brimar, for a warmer presentation. Amperex(very popular), Phillips ECG and Sylvania, for a middle sonic ground. All their nine pin, dual triode miniatures, should last about 10k hours(unless run in an unusually demanding circuit).
Thank you for the responses. I noticed that by turning up the preamp volume (without anything playing), there is clearly a "hiss" coming from the right main speaker. The left side is virtually quiet, except for a soft "hum". Can't say that I notice any degradation on sound quality. But that certainly can be due to gradual degradation over the past 4 years (& an estimated 4,000 hours) & my ears have adjusted to it.
I recall a couple of years ago someone on this forum suggested that I talk with Dave Gordon @ Audio Research. I will do that today.
If it still sounds good to you other than the hiss in teh one channel, try rearranging the tubes in the sp16 in different orders first before replacing.
SP 16 uses 6 tubes. Tubes age at different rates. Location of the tubes in the sp16 slots help determine resulting background noise levels I found. As tubes age differently, moving a "better" tube into a different location can make a difference and buy you time before you are inclined to replace.
Never base tube purchases on the name brand of the manufacturer.
Only an expert reseller can tell who actually made a tube, or its condition.
Fraud and misunderstandings abound in the NOS business, not to mention
the buying and selling of brand names and the relocation of factories in China and Russia etc.
The reliable reseller earns his fee and stands behind his performance rating.
Thanks for the suggestion. I spoke with Calvin at ARC a few minutes ago. He claims that the useful tube life in the SP16 preamp is 3K - 4K hours. I realize that this is just a rule-of-thumb, but that puts my OEM tubes over the top. Although rearranging the tubes might very well decrease the audible hiss, I am equally concerned about the deterioration of sound quality that I might have become accustomed to over the years. So, I think replacement is in order. Rather than "rolling the dice" with NOS, I will likely order directly from ARC.
BTW, one other question: Is it money well-spent to replace all of the tubes with low-noise types or just replace the input tube with a low-noise (& regular tubes for the others)? I realize that the answer can be quite subjective. But, is any audible benefit worth the extra cost? Thanks you, all.
Some years back a friend who was not a "tinkerer" bought a used Hybrid ARC line preamp. Not being sure how old "the" tubes was he contacted ARC and purchased the correct replacement from them directly. It took me some weeks to convince him to let me take the cover off and try one of my old RAM tubes. When we finally did his jaw dropped. No question that immediately it was quieter.
You will find it WELL WORTH the cost, to replace all the tubes with certified, "Low Noise" tubes. If you use the phono stage; they are a must, in that position. The higher the gain of the stage, the lower the noise necessary. If you are not using the phono stage, you won't notice any noise with older or noisy tubes, in that stage.
Considering all of the varied opinions & recommendations regarding aftermarket & NOS tubes, I am admittedly a bit reluctant to "tinker". Maybe this is my way of admitting that my audio system is more of a source of quality listening pleasure rather than an end in itself. Nevertheless, I appreciate Samujohn's point. When it comes to motorcycles & photography, some of my expenditures are hard to justify to the non-enthusiast.
I do not doubt that other tubes might very well be more pleasing to my ear. But I am unwilling to find out which ones they are by trial-and-error. It seems like there are too many variables that affect sonic quality to keep the risk of getting the "wrong" tubes low. Please correct me if thinking is unsound (pun intended).
"Only an expert reseller can tell who actually made a tube, or its condition.
Thats also my opinion. Bargain hunting for tubes by the inexperienced is likely to turn out less satisfying and more costly in the long run. In addition to the variety and quality of tubes that they have in their inventory, the advise and integrity of the best resellers make it well worth the premium you pay. In fact, I would suggest that if one has a well set-up, high quality tube system, a call to one of these experts is almost requisite.
I recently owned the power amp, VS55 that matches your preamp. When I bought it I emailed Jim McShane and was very pleased with his prompt reply and his knowledge. I took him up on one of his suggestions and was very pleased with the results. My trade is law. I do tinker, but I also respect expertise. Especially when the one providing it is willing to explain and offer alternatives.
Rodman99999 makes the point that replacing all the tubes with certified low-noise tubes is "well worth the cost". Since I do not use the phono stage, is there an obvious difference in sonic quality will all low-noise tubes?
"...the quiet ones were where they needed to be (phono input, Post RIAA amp, and line input).The not so quiet ones went where they didn't cause any problems (cathode followers and intermediate gain stages. By doing this we could use 95% of the tubes. You don't need a quiet tube everywhere and that is why RAM Tubes come in 4 grades." RM
The gain is not as high, in the other stages(compared to phono related) of your preamp, but noisy/microphonic tubes will still be audible. Upscale's graded tubes are tested for triode balance, as well as noise/microphony, which will also improve channel balance/imaging, in the SP-16. Everything hinges on how much you value performance.
With my sp16, I hear a tad more hiss/background noise only in the phono stage at higher volumes with nothing playing using the Groove Tube Gold 12AX7s compared to the original "low noise" tubes that came in the unit for ARC. Not an issue for me but for those who cannot handle any extra noise at all in their phono stage ever, it might be.
You might want to consider using tube dampers in the phono stage, at the very least. These tubes are more susceptible to micro-phonics due to the increased gain in the phono stage. When you are using the phono stage you are actually using the phono stage and the high level stage together to get the necessary gain. I use the dampers in both the high-level and the phono stages with excellent results. The ARC tube dampers work very well and are inexpensive.
Thank you, everyone, for your suggestions. This will allow me to weigh the pros & cons of my various options & to make an informed decision. Thanks again.
A note regarding tube dampers.
The tubes in my SP16 came with removable dampers.
I put these on teh new tubes when I replaced them.
The gal at ARC told me that the dampers were not removable and reusable with some older production units. ie they tended to adhere to the tubes over time.
Mapman the new rubber "O" ring dampers are removable and reusable, just don't cover the plate of the tube. Move the ring so it's above the plate structure. The older clear dampers used to melt into the tube.