Xiansheng 708B headphone tube amp

The Xian Sheng 708B is a real nice sound for low bucks (close to $200 USD). Available in the USA from:

http://www.pacificvalve.us/Headphones.html

I got mine used from a fellow head-fier and was interested because I have hundreds of tubes, and many of them are type used in this amp. I thought it would be fun to play with in tube changing.

It uses five tubes: 6n1, 6n3, 6Z4 and two 6DJ8/6922. The 6N1 is the front tube in the window, the 6Z4 rectifier is a lone tube in the back, while three tubes in a row are the front 6N3 the middle 6DJ8 left driver, and the rear 6DJ8 right driver. Russian equivalents are 6N1P (instead of the Chinese 6N1) and the 6N3P (instead of the Chinese 6N3).

It sounds OK with the Chinese tubes supplied but improves very much from tube changes.

I first changed the 6N1 for a new Russian military 6N1P EB (from the 70s or 80s). The sound became cleaner and clearer - sounded better with just this one change.

I next changed the Chinese drivers with two Sylvania JAN 6DJ8 and loved the sound with Mike Oldfield's Amorok - beautiful timbre.

However, this CD sounds good with almost anything so later I tried some demanding but well recorded symphonic works.

Started picking up some euphonic coloration in some tones here and there so I switched to some Amperex-Holland. This was a real nice sound and eliminated any euphonic coloration.

However, I wanted to sharpen the soft tone edges slightly so I used one of my favorites - RCA 6DJ8 tubes, stamped UK on the tube, but actually made in Russia. I bought a bunch of these new and they work really well. The Russian 6n23p (EB or IV for military) made before 1985 are as good.

Getting good sound now - you could spend more and not get any better sound.

This is a great choice in a headphone amp at the price point.

The rectifier is a Chinese 6Z4 (not the old non-Chinese 6Z4), but you can't use the 6X4 instead. Don't try.

I next will try some Toshiba 6DJ8, some Mullards (GB made), Russian 6n23p EB, and whatever else I can find. I also will try a Russian miltary 6n3p tube in place of the Chinese 6n3.

The amp nicely drives the AKG K701 and Sony SA5000 BTW.

All the amps I have owned offer good sound. You have to find the one that suits you. Some seem more of a bargain than others, offering sound that matches more expensive ones - at least in my tastes.

The Xian Sheng is an outstanding bargain.

P.S. Toshiba 6DJ8 tubes are good - sharp tone edge and transient attack bite, with good natural timbre. However, this means that if you have an "edgy" CD or source, you will hear the harshness more than with some other tubes (like Amperex-Holland). However the RCA 6DJ8, stamped UK, are the best.

P.S. Works good as preamp in a speaker system. Much above average in comparison with the other headphone amps, that can serve as a preamp, that I have owned. Plenty of gain for my amp (a real problem for other headphone amps as preamps). Well worth the price for use as a home preamp alone.

For me the Bada PH12 is the best I have owned - though I can see how others might prefer some of the amps I have owned to the Bada.

Something about the soundstage, instrument separation, 3-D tone images pinpointed in empty space - just a certain transparency and realism that makes me there with the music more often than with other amps.

The Bada is my loving wife while the other amps are brief flings - exciting for a short time but they quickly lose their luster - and then I am very happy to return to the Bada for the "real thing". I enjoy new amps for awhile, change tubes ad really get to know and like them. But after a few days I go back to the Bada and really appreciate its superiority - no matter how good the other amp sounded. The day, I don't discover that, is the day the new amp replaces the Bada.

Some will say it is force of habit - that I am too accustomed to the Bada - and that if I only owned their amp I would realize the Bada was inferior to theirs. Might be true - send me your amp and let me hear (lol).

As far as the Xiangsheng vs. Bada PH12, in addition to better 3-D imaging, the Bada PH12 has a better soundstage and more dynamc impact, with more power - greater realism and transparency overall.

However, the Xiangsheng is very impressive in comparison to other lower cost all-tube amps, and is a cost-effective champ when its price is factored in.

The Xian Sheng ($200), Ming Da MC66AE ($300), and G & W T2.6F ($355) are all good for the money.

Xian Sheng - nice timbre, good detail, good dynamics, very pleasing to listen to, good preamp in a home system with plenty of gain (unusual for a preamp/headphone amp) - need to use the tubes I specified. Some slight bass shyness and soundstage restriction.

Ming Da has a little fuller sound with more impact, richer timbre, limited tube options (the power tube is a 12AX7 and offers many change opportunities though, and the Chinese 6N6 drivers are surprisingly good)). Bass is a little tubby.

G&W T2.6F offers plenty of tube changing (two 6DJ8/6922 and mosfets output) and is very clean, detailed, neutral ( tends to be lean but rich enough with two Sylvania JAN 6922), dynamic.

All offer great listening pleasure for the money.

A step up in price is the ASL MG Head III, and some would prefer this one to the others.

I haven't heard the Dared but people say good things about it also.

The $400 and under category offers some real good amps.

There is so much overpriced and overhyped stuff around - buyer beware - high price does not always mean high sound quality. Since judging sound quaility can be very difficult and subjective, it is easy to believe the hype and think you have great sound quality when you actually don't.

Does it do the same with 6DJ8 tubes? I have only used 6DJ8 tubes.

6922 tube draws slightly more power but this shouldn't be a problem.

I have used mine as a preamp in my home video system for over 12 hours at a time with no problems - no sign of overheating.

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My 708B is dead silent and runs cool.

Hum is usually tube related - some tubes are noisier than others even though otherwise good.

Replacing the front Chinese 6N1 tube (in the window) with a Russian 6N1P EB military tube is important also for good sound.


You can have all kinds of problems if you put the wrong tube in the wrong socket.

The front window tube is a 6N1 (Chinese) or 6N1P (Russian).

The single rear tube is a Chinese minature (not old USA) 6Z4.

the three tubes in a row are 6N3 or 6N3P (in front) followed by two 6DJ8 or 6922 (in the middle and rear positions).

Be sure you get the tubes in the correct positions.

Thanks for your valuable input Hirsch.

Do you know what the front window tube 6N1 (or 6N1P) does?

Is it a "preamp" part of the input gain for the drivers?

How about the 6N3 (or 6N3P) located in front of the two 6DJ8 drivers? Is this 6N3 also a part of the input gain that feeds the drivers?

Is switching from the 6Z4 to a 6X4 simply a matter of re-soldering some socket pins? No other circuit changes required?

Although the Bada PH12 is more of a realistic sound, and is my main headphone amp, I intend to keep the 708B as a spare in case my home speaker preamp (or the Bada) fails. I may one day convert the 6Z4 to a 6X4 as I have plenty of 6X4s on hand.