Xiang Sheng 728A Vacuum Tube Pre-Amplifier

First impressions. The reviews for this preamp are all over the place on the internet. I suppose some of it can be attributed to varying quality control or lack of. Some have mentioned the cheap internal components (I would not know anything about that myself). When I connected mine and turned it on I was expecting something like someone throwing a match into a Chinese warehouse filled with Luna New Year fireworks. The startup yielded no such problems, or any that I could detect at all.

This unit is said to be a copy of a Japanese Wada design which in turn was a copy of the Marantz 7 preamp. It does NOT have a phono section so an outboard phono preamp would be needed to play a record.

I bought mine new, and is the latest iteration that does not include tone controls (and no balance control either, damn it!).

I have read where some say it has no bass. Well I have played mine with and without my subwoofer and I would not agree with that. The bass sounds fine, without overhang or bloat. What I did NOT hear was the mentioned bass bloat, any slurring of transients. It sounded a lot like some of the better transistor preamps I have had (Perreaux, Spectral, Threshold, Crown) as far as speed, resolution, transients and soundstage. There is slightly more body and "roundness" going on it seems (or is that simply a psycho-somatic influence brought on by the glow of the tube showing in the window of the unit?).

So far I have no complaints on the sound and for the money it has been worth the gamble to experience a tube preamp in my current system. The only other tube preamp I have had in a system of mine was a Moore-Franklin unit. And I DID experience some bloat going on with that preamp.

Many reviewers found the soundstage became very large and expansive when they introduced this preamp into their systems. I did not note much difference in soundstage so far. I guess I may get into "tube rolling" before this is all over!

 

It's almost been a year now: what's your thought on this preamp? Have rolled some new tubes in there?

 

Sold it. But to tell you the truth, I think it is a pretty good sounding preamp.

 

Thanks. The price is coming down, so I may snatch one if it gets under $250 or so.

 

Your inquiry led me to try another one! I should be getting it this week. This one has the tone controls. I chose it because it shipped from the US and it was the best buy. Now that I have become acclimated to my excellent Threshold FET-1, (avatar) it will be a good time to be even more critical of the XiangSheng 728A. I have just the CDs lined up to evaluate it even further.

 

Sweet! Can't wait to hear about your thoughts on the new unit. As you know now, they are under $300 shipped from US. That's why I bumped the thread.

 

First impressions, second example. This time I got the one with tone controls and a defeat function. I have no use for tone controls, but I DO like having a balance control. Now comparing to my Threshold FET-1. Well it is not easy to go against a Nelson Pass design! The 728A did not pass the transient test I have with a finger squeak on an acoustic guitar on the one cut I use. It sounded like all other preamps besides the Thresholds and Spectrals I have/had. It sounds like a phonograph needle hitting a piece of dirt. Now all OTHER squeaks on this track present no problem. It is just the first one that separates the best from the rest in that regard.

The bass is just as extended, but maybe it is has a bit more "body". Not necessarily a bad thing. I would not go as far as to say it is wooly for too fat etc.

I will have to live with it for awhile. But I would say it is a great way to get into a decent sounding preamp for such a little bit of money. I do not know much about design, parts quality and so on. But its power supply looks rather anemic and cheap compared to even run of the mill preamps. But I am going by LOOKS. I have no idea if that impression is accurate or not. (plenty of pictures of the internals on the internet, if curious).

I wonder what would be an appropriate and not too expensive tube upgrade that might improve the transient attack? It uses 2 12au7 and 2 12at7 tubes. Would just getting some JAN tubes from the 70s be a good way to go? I do not want to spend money on "holy grail" tubes for a $300 preamp. I just want a cost effective significant improvement here. Any suggestions anyone?

 

People complain that the tone bypass switch makes the preamp sound LOUDER when in bypass mode. I think I have figured out why this is so. I THINK the tone controls are merely attenuators. That is when on "max" they are flat and you can only remove bass or treble, not boost it. So when I put them both on "max" I cannot hear a volume difference between bypass or engaged. But when I have them on "min" there is a significant change in volume between bypass and engaged. The tone controls are of little use. But getting the tone control model is the only way to get balance control.

Also, the highs do not have that sparkle the Threshold or Spectrals have. (no surprise there).

 

Thanks for your detailed review. For those of us looking to find an decent but cheap mate for their power amps, the 728a looks like the best game in town. Perhaps it will sound better as it settles in. I can't help you with the tube question (I am curious myself) but I wouldn't want to spend more than $20-30 on a single tube.

 

Yeah I will have to live with it awhile before I can go into more detail. But it seems to be a very good bargain. I think the only way it will come down much more will have to do with the strength of the US dollar.

 

Nice. I picked up the model without the tone controls. I swapped in new production Tungsol's. I have to say I am very impressed. It does require some burn in-leave it one for a few days-perhaps the paper/oil caps? The transients will get better, I probably have 30 hours or so on my.
While it's not as resolving as my high modified Cit21-it's very enjoyable, and addicting to listen too. Both preamps thankfully are free from harshness, and what I call solid state steely grain.
I use it to drive a H/K PA2400 running highly modified ESS AMT3's. The AMT3's seems to extract enough detail out of this preamp, without the aforementioned harshness/grain. The bass is tight, but full. I can't detect any wooliness-something I was afraid of initially. Seems to have enough space and air, without sounding unfocused. Nice imaging.
I also run a Black Ice Foz SSX between the 728a and the PA2400. It enables you to add separation and air, and control any bass issues without negative effects. Excellent unit-I bought a second one for my main system.
Anyhow I'm very happy with the 728a-it's a keeper !! For me, I was slightly hesitant to by the non-tone control model, because the lack of balance control-but after some thought-I rarely use it-mainly as a diagnostic tool-so it's not a big issue for me-I can work around.

 

Oh-just as a added note. Personally I'm not a huge fan of NOS tubes-old production. My experience is most don't pan out to sound as some claim-in audio anyhow. Most seem too dark, too bright, or just plain old sounding with poor gain.
The Tung Sol's remind me of the best in tube sound-full, smooth and tight sounding with out overly exaggerated frequencies.
Personally my ultimate preamp would be a H/K Cit I. Or should I say a McShane upgraded Cit I given their age. I haven't heard a modern preamp that can touch one of these-given it's driving a great amp (CIT II, or V-or compatible SS amp).
They seemed to give you the very best tube sound can give you, with out the draw backs.
Is the 728a close to a CIT IMHO. Nope, but it's still a great sounding unit given the price of admission. But it gives you the ability to hear the advantages of tube preamps driving solid state amps at a great price.
I would recommend pairing with a good amp-otherwise you won't hear it's best.

 

Some asked me a question on gain issues with this preamp. And that it's over driving there current power amp, so there is little volume control range, and possible clipping. Some of it tube dependent. On units with tone controls-these are basically attenuators-you could turn them equally down-but this may affect frequency response. Most hifi amps don't have adjustable input sensitivity. So you have a few options. A outboard volume pot, a bit of a pain. Or a outboard fixed attenuator, such as a Harrison Lab pair. They come in fixed values of 3, 6 and 12 db. Make sure you plug them into the amplifier then plug your patch, otherwise they don't work right.
They don't effect the sound, other then reducing the clipping in you amp's input board, so that would be the only difference you would hear. I have seen some claim they are negative to the sound, but I'm sure a blind test would prove this wrong. It's essentially the same thing as a preamp with a lower output signal.
You just want to prevent overdirve of the input board, and have a useful volume control-not so low your now hearing the noise floor.

 

Keeping the tube rolling aspect of this post going - I found Electro Harmonix 12BH7EH tubes to be quite an improvement over the stock Chinese tubes in the 12AU7 spot. I'd tried a pair of Telefunkens and as one might expect there was more air at the top but the mids were unimproved. YMMV but the 12BH7EH tubes are a keeper in that spot. Now on to the 12AT7 tubes - anyone have a suggestion?

 

Hi Webnick,

I know it's been a while and I hope you're still around.
Have the 12Bh7EHs been a success in your Xiangsheng 728a? I read somewhere that there could be issues with them in some circuits?

 

Hello,
It's been a while, but let me ask you something - can you specify which song are you using for your "transient test"? I'm currently deciding on this preamp + better tubes vs. Maverick Audio Tube Magic + Sparkos Labs Discrete Op Amps. Did you experiment with switching tubes on the 728A?
Thanks!