• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Yaqin MS-300B SET amp

Does anyone else out there have a Yaqin MS-300B amp? I am very impressed given the price I paid. Of course I ditched the tubes it came with and am using Mullard CV-4024s, Vintage '44 Sylvania JAN-CHS 6SN7GTs, JJ 300Bs and a '59 Soviet/Svetlana 5C3S rectifier. The results? Superb!

And check this - the amp runs my B&G RD50 planar transducers just fine!

I have owned and auditioned a LOT of tube amps over the years but where has this amp been all of my life? :)

And it was only $550! (Plus shipping...)
 
My friend heard my Yaqin MC-10L and was so impressed that he, being a bit better off financially than I, bought the MS-300B. I think he also liked the remote control that came with it, I had to build mine as an add on. Previously I had added up the cost of chassis, components, Tubes and Transformers ready to build my own amp but realised that the Yaqin would work out much cheaper. It also would look better than a bare metal chassis, my effort could never look great!
I was amazed like you, that after re-tubing, it sounded brilliant and I have had two years of immense pleasure from it. As for my friends MS-300B? He adores it and has had no problems with it.
Les
 
Hi John. Well I now believe that the Chinese Tubes are probably ok but when I first saw them I mistrusted them due to their internal appearance. They just looked rough, like for example the bow in the plates between rivets which you don't see so much on western versions where the plates are tight all along the seam. The glass to metal seals did not exactly fill one with confidence and the external pins had a rough finish. The Russian equivalents look much better and indeed made my amp sound different, it was not so harsh, much more warmer in sound and improved at the lower end. Most improvement appeared to be made when I replaced the preamp tubes, same type but a different manufacturer, in my case Svetlana. Yet the original Chinese EL34's were given to an impoverished guitarist I know who is over the moon with them. They have been really heavily gigged for some months now in a Marshall Amplifier and no problems so far.
So maybe I was a bit harsh on the original Chinese Tubes, they just looked rough that's all. :)
 
John L said:
What is wrong with the tubes that come with it?

Well I too mistrust Chinese tubes and have been disappointed by their sonic quality, or lack thereof. So I have just gotton used to pulling them. With the MS-300B I actually first listened to the Chinese tubes and said to myself "Not bad! They're getting better!"

But I pulled them anyway.

NOS American and British tubes just sound so much better! Yes I know the JJs are neither but I am not about to buy WE 300Bs...

I was rolling tubes through the 300B today and have a new favorite 9-pin pre-amp tube. None other than the 5-Star GE JG 5751. They sound better than my Mullard CV-4024s.

What I'd really like to find is a pair of those tennis ball 6SN7s for it. Yes, I know they're Chinese ;) But they're supposed to be quite good. :)
 
Yes, very familiar with them and have quite 3 of our re-branded versions (GF A-330B) left, that model is discontinued now, being replaced with a new version with EL-34 driver tubes (GF A-534), which is currently driving a pair of 85db Morel to decent volumes, and it's dual voltage as well. Besides being a great 300B SET, both are also a wicked heaphone amp, letting you experience 300B thru your cans. You need to power down and switch the amp into headpone mode.

btw, the supplied tubes are made by Shuguang who make about 40% of the world's tubes under numerous brand names and their own name of course. They have numerous grade levels for their tubes, ranging from crap to premium, world class.

The Yaqin (and just about any) amps (etc) sold out of Hong Kong are usually the grey market 'made for china' version's which have cheapened parts (to keep it affordable fior the Chinese consumer, who can get it fixed for usually 5 to 10 dollars) and for 110v, unkown transformer origins and zero warranty support.

That includes the tubes, which we have seen various grade levels. Our's are second from the top level and sound really good, but of course rolling can bring some drastic changes to the sound. WHen I roll, I like to come cack to original after a week to really see if the roll made a positive change.

My 10 cents and if you want one of the GF versions at discontinued pricing, PM me. It's a great amp out of the box that can be easily modded into something special.

Ian
 
igrant said:
Yes, very familiar with them and have quite 3 of our re-branded versions (GF A-330B) left, that model is discontinued now, being replaced with a new version with EL-34 driver tubes (GF A-534), which is currently driving a pair of 85db Morel to decent volumes, and it's dual voltage as well. Besides being a great 300B SET, both are also a wicked heaphone amp, letting you experience 300B thru your cans. You need to power down and switch the amp into headpone mode.

btw, the supplied tubes are made by Shuguang who make about 40% of the world's tubes under numerous brand names and their own name of course. They have numerous grade levels for their tubes, ranging from crap to premium, world class.

The Yaqin (and just about any) amps (etc) sold out of Hong Kong are usually the grey market 'made for china' version's which have cheapened parts (to keep it affordable fior the Chinese consumer, who can get it fixed for usually 5 to 10 dollars) and for 110v, unkown transformer origins and zero warranty support.

That includes the tubes, which we have seen various grade levels. Our's are second from the top level and sound really good, but of course rolling can bring some drastic changes to the sound. WHen I roll, I like to come cack to original after a week to really see if the roll made a positive change.

My 10 cents and if you want one of the GF versions at discontinued pricing, PM me. It's a great amp out of the box that can be easily modded into something special.

Ian

Ian, are you the Canadian fellow, who sells Chinese electronics on E-Bay?

I've forgotten the name there, but this person carried several different brands other than Yaqin.
 
Hi John L, rarely sell on eBay but have a few times and used to do vintage synths on eBay. I should add to my signature that I'm Grant Fidelity and will do so. We only do Grant Fidelity versions or re-brands of our manufacturers gear. In the Vendors forum here you will see a couple of our group buy offerings too. Plans are in progress for the Grant Fidelity DIY division, which will be lots of fun.

Hi Rodango, I've seen a lot of exterior mods to the MS-300B (GF-A330B) from customers, like complete exotic tube rolling, transformer cover dampeners, tube coolers/dampeners and power cables that make it sing even better, but no one that I know has done any inside mods. Dave at Planet 10 Hi-Fi has plans for hot rodded versions though of all the GF amps.

Ian
 

Colin151

Member
2007-12-05 11:20 am
Hum

Hi Was wondering if anyone can help?,

I bought a Yaqin 300B amp last week and am very impressed for the money, - great sound. However I am having a problem with hum through the 3 "integrated" inputs tuner, DVD and CD inputs, - there is a faint hum in the background that is not present when using the Aux input.

The Aux input is supposed to be a "pure post stage" input, - Does anyone know what this means?, - does it miss the first valves and hence give a shorter signal path? The Aux input sounds brighter and has less input sensitivity than the ohter inputs as well as no hum. Is this the best input to use (with a CD player) or should I be using the CD input and put up with slight hum?

Any help would be much appreciated,
Cheers,
Colin
 
Recently I was looking about the internet and came upon your site and read up about the MC-300B and particularly Rod Coleman’s suggestions on modifying it to improve the lifetime of the 300bs, (and sound quality too). I duly did his modifications and have to report that it very much improved the sound as the 300bs weren't being over-stressed and sounded much less distorted at reasonable volumes and I felt much more comfortable using it without wondering how long the valves had left to live!
I then changed all the valves bar the 300bs to better NOS / Mil Grade USA/European equivalents and by-passed the big power supply electrolytic caps with good quality poly caps. These changes were all relatively easy as the amplifier has a difficult to move circuit board so I did not want to have to do too much surgery. This lead to further improvements in detail and a cleaner treble, qualitatively the amplifier now sounded like I’d have to part with over £1000 commercially to equal its performance.
However, I have to report that shortly after I completely over-hauled the Music Angel 300B to Lukasz Fikus's schematic. I have to report that it absolutely destroys the MC-300B now. This is such a difference that before the Music Angel just sounded like a £300 amplifier when the MC-300B sounded like a £600-£700 range amplifier,(which is what I paid for them), but now it sounds like I’d have to part with well over £1500 commercially to compete with the Music Angel. So why am I telling you this?
Well I'm going to completely gut the MC-300B and re-make it to Lukasz's schematic, (remove the circuit board and point to point wire it) and I'll let you know how I get on.
 

AudioFanMan

Member
Paid Member
2020-02-10 2:22 am
Long Island
Name this tune!

Reviving this thread! I also now own a MS-300B. I like it very much...

One thing, the startup hum makes me wonder if something is about to go bad...
Attached is a MP3 of what I hear at startup (renamed as mp4 so I could upload) ..

If this is not normal, what should I look at (cap/resistor etc) under the hood as needing attention or replacement ?

If it is normal, is there a modification anyone has made to ease it up a bit ?
 

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