[sonance]

I'm looking into getting a new amp, and I'm intrigued by some of the tube amp options. This will be my first foray into tubes, although I've heard tube amps at dealers and friends homes, although only on speakers, not headphones, and have mostly found them excellent (albeit expensive.)
A general question I have is about biasing and tube life. I know from a friend with a Cary SLI-80 that it comes with equipment to help you easily check the tube biasing to make sure that it is in the optimal range. He says his tubes lasted about two years before he had to change them, which sounds reasonable. What about biasing and tube life with popular amps such as the Singlepower, ASL, MAD, WooAudio lines? How about the new Meier and RSA tube amps?

Some of the amps which sound promising are the Singlepower MPX3 (or PPX3) and the Cary SLI-80 (used.) I've heard the Cary amp in person which takes some of the sting out of its very high price, but I'm somewhat dissuaded because it almost seems like a waste of such an expensive amp if I won't be using it to power speakers as well and headphones, so I would probably sell my main amp if I was to buy the Cary, which would probably subsidize it's cost about $1000-1200. I haven't seen many direct comparisons of the Cary amps to Singlepower or other tube amps (for headphone use), are they better sounding?

It seems like there are a group of amps which target the ~$500 price range and then another group which are closer to $1000. I know it would be hard to quantify the improvement in quality but I'm wondering how much of an improvement the MPX3 is over the PPX3, for example or how the more expensive tube amps compare to something like a Dynahi or Blockhead.

Edit: This is to be used with HD-650 and soon, an RS-1 on its way (I have SR-225s as well) and either a CD3000 or or an SA-5000. The 650s will be the main 'phones unless I love the CD3000s/SA5000s a lot more than I think.

Thanks for your help!

 

[gundam91]

There are multitudes of tube amp designs (hybrid, SET, Pentode, etc.), not all require manual biasing.

Most of the headphone amps are more like integrated amps, meaning they have volume control and all you do is plug in the source (like CD players).

Some of these integrated amps use tubes in the input stage and solid state in the output stage. These are the most easiest to operate. Some use one tube, some use a matched pair. And these tubes should last for a long time, 3-5 years, depending on how you operate the amp (how often you turn on/off, how long you leave your amp on each day) Most common tubes are 6DJ8/6922/7308/ECC88/E88CC/E188CC or 12AX7/5751/ECC83 or 12AU7/6189/ECC82. These are "signal" tubes. (I include all the different tubes that are substitutable. "E" series are the european designation of the same tubes).

Triode, Pentodes, and Push-N-Pull are just a few types of pure tube amps in which you have two sets of tubes. One set for input stage, and one set for output stage. The output stage usually runs really hot. (You can burn your finger if you touch it). These are the tubes that will usually go out first. Most of the earlier designs require that you need to bias the tubes with something like a volt meter. Many of the designs these days include auto-biasing, so you never have to worry about it. So all you really need to worry about is chaging tubes every 2 to 3 years. Or if you like, tweak the amp with NOS tubes, as they will change the sound characteristics of your amp.

You need to make sure that these amps can drive the cans you want. HD-650 has high-impedance. It is fairly easy to drive. RS-1 and the Sonys are considered low-impedance cans and needs more power. Some amp will have a hard time driving those low-impedance cans.

Also, not all tube amps sound the same. There are tube amps that sound fast and bright like solid state amps. I've heard a SinglePower MPX3. I would not put it in the same category as the Cary as I think the MPX3 sounded more like solid state amps. But my understanding is that you can customize the parts in the MPX3 which may make it sound more "tubey".

If you are looking for tube amps, I would recommand also taking a look at some of the products coming out of China. I've been pretty impressed with their tube audio gears. I have two of them. A hybrid (HP-100A) and a Triode (Consonance Cyber 20 by Opera Audio). Good products with great prices!

But ultimately, I would recommand listening for yourself to see what you like, and what sounds good in your system. Best way is to attend one of the local meets, meet some folks, and see if you can borrow some of these products for an in-home audition.

 

[Len]

As for your biasing question, most headamps are probably auto-biasing, so you needn't worry about it. Tube life varies depending on circuit and tube type. Most last at least 2-3 years, with some lasting decades. In most tube headamps, these tubes aren't being driven very hard (I think the Wheatfield is an exception). You should expect at least 2 years life, and likely much more.

 

[sacd lover]

I think the singlepower mpx3 sounding solid state, to you, would be due to the tube set you auditioned in the amp (or possibly brightness from somewhere else in the signal chain). If you use the stock EH tubes, I agree, the amp sounds very solid state like to me too. When I put in some better sounding nos tubes like a tung sol clear glass / sylvania combo in the amp, the result is still basically neutral and lively but definitely more liquid. Put in a tube set like a RCA gray glass with two sylvania gta's, with my amp, you get a warm, smooth relaxed sound.

I have four mpx3's and the tubes in use in the amp make far more difference than the options. For instance, the paper-in-oil cap upgrade vs the stock orange drop caps have a slighly different sound (more transparent and resolving vs more dynamic). But the basic sound remains very similar with the same tube sets. If you want the mpx3 to be tubey use warmer sounding tubes like the RCA's.