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Xiansheng 708B headphone tube amp

post #1 of 413
Thread Starter 




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.
post #2 of 413
Compared to bada ph 12?
post #3 of 413
Thread Starter 
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.
post #4 of 413
Quote:
Originally Posted by drarthurwells

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.
Well, i also owned an expensive maxed out stax system, wich was inferior to the bada ph12 and hd650 combo in a lot of respects! Especially timbral correctness and the rich full body is a treat. The electrostats sounds mostly very detailed but thin and dull. Also bass is a weakness of electrostats in general! The bada sounds natural, like the real instruments and give you a great live feeling, like really being there, an electrostat is more detailed(also depends on source/headphone combo) but fails in other departments.

Until the bada, i never heard a heaphone amp that sounds so real! And i tried a couple!

Others might have more detail, but they never have the timbre and natural, neutral sound as the bada and don't portrait the live feeling as i have with the bada! In other words, if you wanna listen to real livelike music, the bada is a great amp, if you want micro-detail, look elsewhere.

Also heard alot of more expensive amps wich don't have the correct timbre and body as the bada, also poweramps for speakers!
post #5 of 413
How does this compare to the ming da 66?
post #6 of 413
Thread Starter 
Quote:
Originally Posted by Fang
How does this compare to the ming da 66?
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.
post #7 of 413

XiangSheng 708B Smoke!

AfterI have own the 1st one of this model 708B...I got it smoke on the R-Core Transformer!Well I switching it off and wait till it cold.Open it! nothing strange but the R-Core almost Brown and Smell of Burnt...
I put it on it still working but after 30 mn it again Smoke came from the R-Core...I send it back to China after that and still wait it will send me back but i can't wait then i bought the 2nd again!Well Same problem after hours it smoke again.!Now i'm sick what wrong with my these two amplifiers?
By the way it sound incredible for suck a small machine.I also owned VAL E-10(138 $) that have with 2 inputs so i hook 2 PCs on it.(Mac/PC)But sound are not good as 708B.That why I bought 2 of them.But I never have a chance to get it to work as i wish too...Any one help me please what I should do!

-I hook a pair of highspeakers from VAL M-20MKII(108$)on ebay! thought the out put behind not the earphone out put.Are this should be a problems?
-I have changed the 6N11 to 6922 gold pin from Tesla Should this be a Problem too?
post #8 of 413
Thread Starter 
Quote:
Originally Posted by titoyd
AfterI have own the 1st one of this model 708B...I got it smoke on the R-Core Transformer!Well I switching it off and wait till it cold.Open it! nothing strange but the R-Core almost Brown and Smell of Burnt...
I put it on it still working but after 30 mn it again Smoke came from the R-Core...I send it back to China after that and still wait it will send me back but i can't wait then i bought the 2nd again!Well Same problem after hours it smoke again.!Now i'm sick what wrong with my these two amplifiers?
By the way it sound incredible for suck a small machine.I also owned VAL E-10(138 $) that have with 2 inputs so i hook 2 PCs on it.(Mac/PC)But sound are not good as 708B.That why I bought 2 of them.But I never have a chance to get it to work as i wish too...Any one help me please what I should do!

-I hook a pair of highspeakers from VAL M-20MKII(108$)on ebay! thought the out put behind not the earphone out put.Are this should be a problems?
-I have changed the 6N11 to 6922 gold pin from Tesla Should this be a Problem too?

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.
post #9 of 413
Thread Starter 
deleted duplicate post
post #10 of 413
I bought a Xiang Sheng 708b myself recently and my experience is similar, the sound is great for the money. I like the sound better than my Xin Supermacro IV personally, I feel it has more impact, timbre and better treble extension. So far I have swapped the Chinese 6N11 pair for a matched and balanced pair of JJ E88CC tubes. I realise opinions of JJ tubes vary but I personally felt it was quite an improvement over the original ones, the sound became cleaner and smoother, especially for classical music. I was mainly just trying to see if current production tubes would sound acceptable since they are very easy and cheap to obtain. I also plan to pick up some NOS tubes to try, the way I see it, things should only improve. I'd like to shield the transformer more, there is a tiny bit of hum that creeps into the headphone output, I believe because the wire is so close to the transformer. I'm also considering upgrading the large capactiors although that's more of a long term plan.

titoyd, I think you were the person who emailed me earlier via ebay regarding your amplifiers. As I mentioned in the email, I haven't seen any smoke from mine even after many hours of use. There is a definite smell that is a little like burning but to me that is a smell I associate with tubes, I don't believe there is anything actually wrong with that smell. I hope you find an answer to the smoking because this really is a lovely sounding amp.
post #11 of 413
Thread Starter 
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.
post #12 of 413
Thanks for the comparing the amps, one more question though, which one is more suited for beyers?
post #13 of 413
Quote:
Originally Posted by mirumu
I bought a Xiang Sheng 708b myself recently and my experience is similar, the sound is great for the money. I like the sound better than my Xin Supermacro IV personally, I feel it has more impact, timbre and better treble extension. So far I have swapped the Chinese 6N11 pair for a matched and balanced pair of JJ E88CC tubes. I realise opinions of JJ tubes vary but I personally felt it was quite an improvement over the original ones, the sound became cleaner and smoother, especially for classical music. I was mainly just trying to see if current production tubes would sound acceptable since they are very easy and cheap to obtain. I also plan to pick up some NOS tubes to try, the way I see it, things should only improve. I'd like to shield the transformer more, there is a tiny bit of hum that creeps into the headphone output, I believe because the wire is so close to the transformer. I'm also considering upgrading the large capactiors although that's more of a long term plan.

titoyd, I think you were the person who emailed me earlier via ebay regarding your amplifiers. As I mentioned in the email, I haven't seen any smoke from mine even after many hours of use. There is a definite smell that is a little like burning but to me that is a smell I associate with tubes, I don't believe there is anything actually wrong with that smell. I hope you find an answer to the smoking because this really is a lovely sounding amp.
Hello Mirumu and drarthurwell,
Yes it's me who wrote to you and aalso many buyer in the ebay that bought this 708B from jennychan...!She is good seller and also sold such cheap price for the good amplifier event the big amplifier...Don't know if she won some money back after that?
Nobody had same problem like me...as i told your guy I had two of this 708B and they all smoked!I prefer to get it smell than the smoke and heating from the R-Core one.every new tube amplifier will smell after you turn it on at the first time but not longer than 4-5 hours listening it will not smeel any.But smoke seem it make me worry about that i still not see any problems;since i have wait till it cold and checking inside there is nothing strange except the r-core that gettng brown like burning.The VAL E-10 i had didn't use the same transformer like 708B...But it use only one tube (6922)ECC88...The sound are ok for who want to listen just for a pop musics...I love the sound of 708B...
But i may be try the pre-amplifier from the Xiansheng 728 III Vacuum Tube Preamp one cause i don't listen too much the headphone...so i can hook my VAL M-20MKII on it...also alots of inputs...But i still afraid to get the same problems like 708B...Because they look like same build...
I beleive i'm not mistake on the positions of all the tubes even the second one i didn't event open the cap to change the tubes but it still gave me same problems...
I'm living in france and here we use 230 volts like some europeane countries here too.the 708B it wrote that it 's 220-240 Volts so there should not be the problems...The 6922 tubes also should not be the problem...!but seem the r-core sending and working too much to drive all the tubes (5 tubes) don't your guy thing so?
I also owned the Mr'Liung 2002 EL34but I didn't turn it on often because after the fews hours of using the sound balance are gond ;..the left chanel getting lower than the right chanel.This may cause from the heat of the tubes and i have found many user have same problems like me from the mr,Liung 2002.But the 708B no one have same problems with me.If it happen with only one machine I still get it but all the two of mine theay had the same problems...so let say may be my electric circuit should give this problem ? hmmm!but why not the other Head phone like VAL E-10 i got one..It run just fine and so far so good!But i want the 708bB run fine like the other...
post #14 of 413
Quote:
Originally Posted by drarthurwells
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.
A 5670 is usable in the driver sockets, unless the circuit has changed dramatically from 708A, whch I owned. Amperex are very good. However, the best of them, the Westinghouse 396A is not. It exposes too much of the weaknesses of the amp.

Quote:
I next changed the Chinese drivers with two Sylvania JAN 6DJ8 and loved the sound with Mike Oldfield's Amorok - beautiful timbre.
I found that staying within limits was big help. Sylvania's are a good choice. I used some RSD PCC88's from Eastern Europe that worked particularly well. This is another slot in which you don't want to get out of hand. Premium tubes, such as Siemens 6922's did not sound as good as the cheaper ones.

Quote:

The rectifier is a Chinese 6Z4 (not the old non-Chinese 6Z4), but you can't use the 6X4 instead. Don't try.
To use a 6X4, you need to rewire the rectifier socket pin out. This is not difficult to do. The problem comes later, when you try and put the cover on, and discover that the 6X4 is taller than the case

Has the 708B eliminated that awful turn-on hum that plagued the 708A? It didn't hurt anything, but you didn't want to be wearing headphones until the hum had passed.

I found the Xiang Sheng to be a beautiful example of synergistic design. Stay within the limits of what it's trying to do, and you get beautiful harmonic structure. Try to go overboard, and improve too much, and you lose what the amp does well.
post #15 of 413
Thread Starter 
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.
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