The Yaqin MC-100B went thru some serious testing as posted at DIY Audio. It appears the amp struggles to make 25 watts at a rating of 60 watts per channel from the manufacture. It uses KT88 tubes. The amp has some technical issues per the testing here.
The lower cost Yaqin MC 13S was tested at 28 watts per channel with less than 1% distortion and likely makes the advertised 40 watts per channel although I have not seen that measurement. Preamp tube line-up is 12AX7 driving 12AU7. The 12AU7 is not the best sounding tube as a preamp, but used in phase splitter service as in the MC-13S, it is less critical. A 6SN7 to 12AU7 adapter could be used. The power tube is an EL34. The EL34 is known for a warmer sound vs the KT88 family. The EL 34s have been reported as a good sounding tube as supplied from the factory, thus a few were not inclined to change to another brand. If you want a tighter sound, The reissue Genelex KT77 would be a great swap. A review like the one performed on the MC-100B has not been performed. However at $230 less cost I think I will order a MC-13S after my present vintage amp rebuild is finished.
The lower cost Yaqin MC 13S was tested at 28 watts per channel with less than 1% distortion and likely makes the advertised 40 watts per channel although I have not seen that measurement. Preamp tube line-up is 12AX7 driving 12AU7. The 12AU7 is not the best sounding tube as a preamp, but used in phase splitter service as in the MC-13S, it is less critical. A 6SN7 to 12AU7 adapter could be used. The power tube is an EL34. The EL34 is known for a warmer sound vs the KT88 family. The EL 34s have been reported as a good sounding tube as supplied from the factory, thus a few were not inclined to change to another brand. If you want a tighter sound, The reissue Genelex KT77 would be a great swap. A review like the one performed on the MC-100B has not been performed. However at $230 less cost I think I will order a MC-13S after my present vintage amp rebuild is finished.
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