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To those who are looking for "substitutes" for the 6SN7, my own experience is that nothing else on earth can sound as good, or so varied by mfr. and type, as a vintage 6SN7GT, 6SN7W, 6SN7WGT, 6F8G, or 7N7. Truth in selling and price ARE serious issues. However, you can try a used tube dealer with whom I have dealt over a number of years, BYRD, at firstname.lastname@example.org. I have always found him to be scrupulously honest in his measurements and reasonably priced. I have no commercial affiliation with BYRD, except as a very content buyer. However, I don't know what his current 6SN7GT inventory looks like these days.
Interested to hear comments of tubes in amplifier stage vs buffer stage. I just got a Schiit Freya and it takes 4 tubes, 2 for the amplifier stage and 2 for the buffer stage.
So far I bought 6 tubes to play with: 2X Kenrad VT-231, 2X Sylvania VT-231, and 2X Sylvania 6sN7 1952 chrome domes.
I like the Kenrad in the amplifier stage so far for the bass. At the moment I like the chrome domes in the buffer stage.
There is a lot of talk about the sonic characteristics of different tubes in the amplifier stage, but what sorts of tubes should one be putting in the buffer stage?
What is the difference between Buffer and amplifier stage? Does the freya come with tubes? Can you use one of the stages only or youd have to use both?
Does anyone know of a genuine supplier of psvane/shuagang tube/valves on ebay??
They usually say it on their e-bay page but there's no way to know for sure.
Could someone knowledgeable give us a short description of how tubes are matched and what sufficient matching is?
I'm talking to a guy saying two tubes tested excellent on a calibrated Hickok TV-10 with 1650/1650 being nominal one tested at 2750/2750 mhms and the other at 2750/2700 mhms. Based on those numbers, he says they're perfectly matched. Comments?
The general idea I believe is that the plate current between tubes should not vary by more than 5%, and in this case it seems like the variation is 50/2750 = 1.8%, so if the measurements are correct, they would indeed be a matched pair.
Most people don't have the equipment to test if tubes are matched. Sellers will compare the tube structure and the mutual conductance but people who really understand this will say that is just a fair guide.
According to Bob Putnak, at tubesound.com who is one of the gurus...
(4) the fourth school of thought is “total distortion” — meaning that output tubes are truly matched when the total distortion of your amp is lowest vis-a-vis another set of tubes.
Neither a tube tester, nor a curve tracer, measures an amplifier’s output distortion. For that, you need an automatic distortion meter and low-distortion signal source, and a lot of experience. The tubes are placed into the amp, biased correctly, and driven to max output before clipping. Distortion is measured. Tubes that do not pair well together will have higher residual distortion than a nicely matched pair. This method also allows you to measure the amp’s power output from each pairing of tubes.
In my opinion, this is the only real method to accomplish “matching”, although it is not strictly a “tube-matching” issue and therefore beyond the scope of what most end-users want to tackle. It is holistic health care for your amp. You are evaluating all aspects of the amp simultaneously and how they interrelate to each other. You are tweaking the entire amp (including the tubes) to achieve the cleanest output. You are tweaking the bias. You are tweaking the “AC balance” / “phase inverter”. You are swapping/mixing output tubes. You have objective scientific evidence (the distortion numbers) to prove how your amp is working. When you can’t get the amp any cleaner at the same power output level, you know that the amp is optimal within its design limitations. This requires a lot of experience as a technician and quality test gear.
Honestly, this is the “right” way in my opinion and anything else is a serious compromise. But since this would require everyone to become a technician, folks are looking for an “easier” or “simpler” way to match tubes.
You can read the entire text here.
Sounds like tube matching, as offered by most tube sources, is just a gong show then.
But, realistically, even if your tubes are severely mismatched and you end up with a 1-2 dB difference from right to left channels, that will be hard to notice, no?
Considering to get a Shuguang Treasure CV181-Z.
Are the tubes sold by http://psvanetube.com any different from those from ebay or other stores?
They say they only sell "select" grade tubes. Anyone got them from ebay and happy? Price diff is quite big.
Not sure if this is any help but I bought a matched pair Psvane uk-6sn7 from Amazon.co.uk and am very happy with them. It worked out cheaper because I would have had to pay customs.
I have a pair of the PSVANE CV181-UK. I have to say I enjoy the sound much, as well as the coke-bottle look!
I have no idea about the differences between the CV181-Z and teh CV181-UK though, except the CV181-UK is clear glass.
I don't myself know the difference, but the UK has a nice warm presentation, oh and the coke bottle look!
Did Psvane uk-6sn7 fit in the Freya without a tube saver?