From Yaqin MC100B to Tube Distinctions Classic Series

[Steve Toy]

Not so conclusive on the Yaqin amp at Anthony's yesterday.... There was me liking it lots with Ella Fitzgerald but liking it less with Ray Lamontagne. It was simply too mellifluous and smooth although wide-open and well-separated in terms of imaging and instrumental separation. I can't fault its timing/phase coherence abilities in relative terms either. It simply lacked a little leading-edge attck and tunefulness for my liking.

I now believe that the Soulmate pre has its part to play in a little reticence above having plugged it into my own system. Whilst it works very well in Anthony's own setup, I've found it a little bloated and veiled in my own compared to the Spectral pre that I've now put back into my system. Anthony's Grounded Grid valve pre sees the lot off btw - that is a superb pre that does everything right musically. The Croft may sound a little more wide-open but the grounded grid one-box pre of Anthony's just gets on with pure musicality that little bit better imho, having more in the way of stop-start snappiness to it. Whilst its bass seems leaner and meaner, I've come to realise, especially after trying both the Soulmate and the Spectral since, that its bass is tight, dry and meaningful, fitting in much better with the rest of the frequency range. Both the solid state amps simply sound bloated and veiled in comparison.

Even before this, while at Anthony's and using the Soulmate, I was convinced that Ian would be very happy indeed with the Yaqin after Anthony has improved it beyond recoginition as it is certainly a class performer. My only concern was that it sounded a little too polite in terms of dynamics althouth the separation, timing, coherence and soundstaging were clearly in the Big League.

Perhaps with the Croft or the Grounded Grid it may yet prove to be a class act to compete with the very best out there regardless of the cost.

A comparison with the Puresound AOS of mine may prove to be interesting indeed in a given chosen setup.

[Marco]

Even before this, while at Anthony's and using the Soulmate, I was convinced that Ian would be very happy indeed with the Yaqin after Anthony has improved it beyond recoginition as it is certainly a class performer. My only concern was that it sounded a little too polite in terms of dynamics althouth the separation, timing, coherence and soundstaging were clearly in the Big League.


LOL. What you didn't know before you wrote this is that as soon as you left Anthony put the amp back on the bench and re-voiced it to sound as it did before Ian told him he thought your amp sounded too forward!

After speaking to Ian and hearing what he thought of your amp Anthony thought that the Yaqin might sound too 'upfront' for Ian so he made it sound smoother, hence your comments above. It is now back to normal, and from speaking to Anthony last night at length, sounding better than ever :)

We're going down on Thursday to pick up Ian's amp and taking his Croft with us, so the results should be very interesting... On the way back up we'll pop by mine and I will get an opportunity to hear the amp in my system for the first time. I'll let you know what I think!

Marco.

[Filterlab]

http://s560.photobucket.com/albums/ss49/aos_images/random_stuff/Tubedistinctions-1.jpg

[Marco]

Hi Rob,

Thanks for that, but Steve's already posted the pic in the Gallery under a separate thread :)

Yours is a better picture, though (as usual)!

I'll move Steve's comments about the Yaqin on the Chesterfest thread to here and keep your picture and the thread relevant.

Marco.

[Ian Walker]

Whats a Yaqin?.

[Prince of Darkness]

It's a chinese valve amp. Apparently very good, when suitably modified.:)

[Marco]

I think you've missed the Irony there, Kevin :)

Ian owns the amp in the picture above, which was once a Yaqin, and is now, erm, just a 'tad' better than that ;)

Basically, there's very little of the Yaqin left apart from the chassis!

I had the pleasure of listening to this amp yesterday in three different systems and it is stunningly good - several leagues better than my own Yaqin, but mine will shortly be modified just like Ian's.

Marco.

[Prince of Darkness]

I'm on Nightshift this week. So brain is only working sporadically.:doh:

[Marco]

Not so conclusive on the Yaqin amp at Anthony's yesterday.... There was me liking it lots with Ella Fitzgerald but liking it less with Ray Lamontagne. It was simply too mellifluous and smooth although wide-open and well-separated in terms of imaging and instrumental separation. I can't fault its timing/phase coherence abilities in relative terms either. It simply lacked a little leading-edge attck and tunefulness for my liking.


Steve, since Anthony re-voicing the amp (lowering feedback) these comments are now rendered totally obsolete! ;)

Marco.

[Ian Walker]

It's a chinese valve amp. Apparently very good, when suitably modified.

Doh there was me thinkin it was Chinese forum for laughs..Yakk in:lol::lol::lol:

[Marco]

I think I seen some Chinese brides for sale somewhere... :scratch:

Marco.

[Primalsea]

I'm interested to know what the quality of the transformers are like. Chinese transformers are often large and look substantial but I hear that the quality of the metal if poor. Saying that though, I used to use some small EL84 Chinese amps and they sounded really good. A bargain too at around £150 each.

Also is the voltage issue really a problem. A transformer rated at 230V probably uses the same components for one thats rated at 240V, its just that it has less secondary windings. The only problem I can see is that the B+ will be higher than intentioned which may mean that the valves are not a a optimum operating point. Also heater voltage will be higher too which will reduce valve life.

[Marco]

Hi Paul,

Nick and Anthony are your men for that particular query.

As far as I understand, based on experience so far, it's not the quality of the transformers that's the problem with Chinese amps - they can handle UK voltage ok, it's the over-voltage (often 30V or more on some UK mains supplies over and above the 220V rating of the transformers) on the secondary windings, where components are of poor quality (caps for example) without sufficient tolerance to handle the over-voltage, that's the problem. That's why they blow up without a step-down transformer!

As for actual transformer quality in terms of metals used, consensus of opinion appears to be that they're 'ok' but nothing special and easily bettered by something from, say, Sowter.

I will be having Sowter transformers fitted in my own Yaqin when further modified by Anthony, once I compare Ian's amp to Steve's and decide for sure which one I prefer in my own system.

Marco.

[anthonyTD]

I'm interested to know what the quality of the transformers are like. Chinese transformers are often large and look substantial but I hear that the quality of the metal if poor. Saying that though, I used to use some small EL84 Chinese amps and they sounded really good. A bargain too at around £150 each.

Also is the voltage issue really a problem. A transformer rated at 230V probably uses the same components for one thats rated at 240V, its just that it has less secondary windings. The only problem I can see is that the B+ will be higher than intentioned which may mean that the valves are not a a optimum operating point. Also heater voltage will be higher too which will reduce valve life.
hi,
the main problem with the chinese amps in this case the yaqin 100b/110b is the over voltage when you try to use them on our mains supply, being when tested using a variac to find out the original design voltage ratings of the secondary windings when on load ie, amp on, drawing current etc,i found that on the 100b coming in from hong kong the primary mains voltage was 207v ac to give 6v heaters and 490v HT!!! which as you can probably work out, when this amp is used on our mains voltage, which varies easily between 238v and 253v depending on what time of day it is, and where in the country you are is way out, and because the heater voltage is around 7.3v at 240v ac, the valves will not only have a shorter life but will suffer from run away, ie, the valve will produce much more emision on 7.3 volts than it would on 6v. also, to add to this the HT voltage is around 50 to 60 volts higher, which will put even more strain on the valves, and the rest of the components, ie, power supply caps, resistors etc.
the output transformers on these amps are not bad, although in their original form, these amps use more feedback than is necesary to get a false extension of percieved frequency response.
regards,anthony,TD...:)

[Ali Tait]

Was round at Nick's recently and we tried some James and some AE amorphous-cores on my Mr Liang.I was expecting a significant improvement,but that was not the case.Quite surprisingly,the stock trannies were quite a bit better than the James,and while the AE's were better than the stocks,there wasn't a great deal in it.Not what I was expecting at all! The Liang does differ from the usual chinese fare in that the outputs are wound in-house and not cheaply made mass-produced generic items.

Regards.

[Marco]

Hi Ali,

Pity you couldn't make it to Chester as Dave Hewitt's Mr Liang unfortunately sounded total pants after he modified it - nothing like yours did at Owston :)

I believe it had the wrong caps in it, though, and now sounds much better.

His little 5-watter thingy on the day blew it away (and quite a few other things, too)

Which I guess in a way relates to what you've just described.

Marco.

[Primalsea]

I would imagine that the step down transformer used will have an impact on the sound as they will lower output impedance and low quality ones will probably have a few design flaws of their own as well.

Would removing a few of the secondary windings to lower the secondary voltage be a suitable fix. I imagine that some amps probably don't operate at optimum HT due to design oversight. Removing some secondary windings could allow the HT to be tuned to a limited degree.

[anthonyTD]

I would imagine that the step down transformer used will have an impact on the sound as they will lower output impedance and low quality ones will probably have a few design flaws of their own as well.

Would removing a few of the secondary windings to lower the secondary voltage be a suitable fix. I imagine that some amps probably don't operate at optimum HT due to design oversight. Removing some secondary windings could allow the HT to be tuned to a limited degree.

hi,
the step down transformer would actually raise the impedence, but i think that is what you meant, anyway, it would be very difficult to even get most modern mains transformers apart because they are resin dipped.
anthony,TD...:)

[Primalsea]

Whoops, Yer I did mean increase OP impedance. I'm having a mix up day today, just replaced the resistors on a Leak ST20 and got them mixed up! 29V on the HT is not right at all.

With the increase in HT I suppose that it would give the possibility to fit voltage regulators. SS I guess as valve regs drop too much voltage.