• 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 MC-100B - not as powerful as advertised, but still a good value.

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#201
Hi has anyone tried changing the output transformers on the yaqin mc-100b.
I have noticed it lacks deep bass I suspect it rolls off early with these transformers.
Reading reviews a lot of people say the output transformers are the weak point.
What would be good replacement output transformers for this amp without spending too much ?
 
#202
This is not viable option. Good transformers are more expensive than this all amplifier. Why not to get one done right to begin with like Mc 2xx line or one of older Conrad Johnson's, or Line Magnetic (if you want pure Chinese gear). As for MC100 - you need tube friendly speakers for it. But you won't get dance club levels of bass from almost any tube gear. It is just not designed for that application.
 
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#203
avp1 said:
This is not viable option. Good transformers are more expensive than this all amplifier. Why not to get one done right to begin with like Mc 2xx line or one of older Conrad Johnson's, or Line Magnetic (if you want pure Chinese gear). As for MC100 - you need tube friendly speakers for it. But you won't get dance club levels of bass from almost any tube gear. It is just not designed for that application.
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Thank you for your advice I really like the sound of this amp I just wish it done the deeper bass.
I'm not looking for big power most of the time I don't have this amp past 1/4 volume I just think its lacking say 40hz downwards at a guess.
I did notice company's like bluebell audio do output transformers flat 20hz to 20khz for about £100 but didn't no what the quility was like & which one to pick.
 
#204
For really deep bass add subwoofer crossed at 60-80Hz. it will takes care of extremely low frequencies and Yaquin will do the rest. Subwoofers like ones from SVS or HSU can easily as low as 16 Hz. It will cost you money similar to MC100 price though.
 
#205
avp1 said:
For really deep bass add subwoofer crossed at 60-80Hz. it will takes care of extremely low frequencies and Yaquin will do the rest. Subwoofers like ones from SVS or HSU can easily as low as 16 Hz. It will cost you money similar to MC100 price though.
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Thanks for your reply.
I have got a sub and have added it to my front speakers it's a Tantra TS12 I picked up cheap from eBay for my home cinema more than anything.
This also goes down to 15hz but still seems to go deeper on my av amp.
I think I should explain how I've got my system set up.
I have a onkyo av amp that's sounds terrible as a sterio amp hence the sterio amp.
I use the front outputs from the av amp into my aux of my yaqin for tv and movies.
I have my dac connected to the cd input of yaqin for sterio when playing music.
If I have the sub connected to my av through sub out on movies the bass really drops and I feel explosions ect.
I have now got sub connected to yaqin speaker line conections it sounds really good and intergrated well with my main speakers set to about 50hz but I loose the low stuff on movies even if I turn the sub up louder than if it was connected to av amp.
So my thinking was that the output transformers stop the frequencies going down that low.
The other option I have thought of is adding a tube pre amp using the pre amp outputs to the sub and yaqin and having the av amp also going into the pre amp.
I still think the yaqin is a great amp it's the only amp I've had where I can listen for hours without saying that's enough or reaching for the volume on certain tracks because they shout at me.
Voices also sound much more in the room and realistic.
Thanks again for your help.
 
#207
I have about 50 hours playing time on my Yaqin MC-100B. I replaced the tubes with Gold Lion Kt88 and 12AX7 and EH6SN7. It sounds pretty good, but when I listen to a vocal (opera for example) with a very high frequency, the high frequency sounds too loud. In other words I assume there is some part of the circuit to balance the low, medium and high frequencies, but it isn't working. Is this because my tubes are new or is it a problem with the tubes. BTW I cant see the filament (red) on the 12AX7. I assume they are just covered. Is that right? If they were burned out, I assume the amp wouldn't work, is that correct?
 
#209
Steventrus, I ran into the same thing. Do you have an early model, or a recent one? If you have an early one you can replace some caps inside, and that's supposed to help -- I havent' done it yet though so I can't tell you.

For me, getting the low end I wanted necessitated running Tung Sol KT120 tubes, with bias set to 1.0v-1.2v. (1000mv-1200mv)

Charles.
 
#211
Thanks ChopperCharles,

I would guess that I have a newer model as I just bought it in November 2014. I just bought a quad set of Gold Lion KT88s, so I really don't want to try a different set of power amplifiers at this time.

I have heard that changing some resistors / capacitors can improve the system. Does anyone have any recommendations in that area?

Steve
 
#212
Changing the caps will give you the best sound upgrade possible, way better than changing tubes IMO.
I've tried multiple caps, now I ended with Audyn True Copper 1uf and love them.
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#217
I will definitely follow your recommendation to upgrade the coupling caps.

I mostly listen to classical / opera and so the bass is fine the way it is. I do have a different but possibly related issue - The treble is sometimes too high, while the bass and mid-range are fine. Will the .1 fix that problem?
 
#220
You cannot have much more bass than now - transformers will get saturated. Sometimes when you increase coupling capacitance too much you might make amplifier unstable. So I d jot recommend blindly change components if you do not have measurement tools and knowledge required for fine tuning.
 
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