jwalker
Well-Known Member
You made a sensible choice. For the price of admission, it's hard to beat some of the amps coming from China.
Shuguang vs. Yaqin
- Thread starter cubdog
- Start date
You made a sensible choice. For the price of admission, it's hard to beat some of the amps coming from China.
cnh2
Super Member
Humming is sometimes a simple ground loop problem. I had experienced some on my Jolida. After trouble shooting it and finding the culprit. It is NOW DEAD QUIET!
I don't think you can go wrong with MOST of the major Chinese brand tube amps. I have personally toured a couple of the actual factories in China where these amps are made, talked to the workers, engineers, owners and been pretty impressed with the product. Some of these amps have been in continuous production for over 15-20 years! Many are based on proven Western designs and have been tweaked by very competent Chinese engineers!
The distinction between American and Chinese made tube amps will become less and less relevant as time passes and the American boys will soon find it very hard to "justify" their much higher pricing! Chinese manufacturing is just getting better and better!
I'm sure you'll enjoy the Shuguang. I've used some of their tubes and been pretty happy with them. Tube snobs aside!
cnh2
I don't think you can go wrong with MOST of the major Chinese brand tube amps. I have personally toured a couple of the actual factories in China where these amps are made, talked to the workers, engineers, owners and been pretty impressed with the product. Some of these amps have been in continuous production for over 15-20 years! Many are based on proven Western designs and have been tweaked by very competent Chinese engineers!
The distinction between American and Chinese made tube amps will become less and less relevant as time passes and the American boys will soon find it very hard to "justify" their much higher pricing! Chinese manufacturing is just getting better and better!
I'm sure you'll enjoy the Shuguang. I've used some of their tubes and been pretty happy with them. Tube snobs aside!
cnh2
Poultrygeist
Lunatic Member
Having owned several excellent tube amps from China I couldn't agree more.
I'm still baffled by those who remain clueless and refer to Chinese gear as junk.
raindance
Member
The hum I refer to is mechanical hum. Not through the speakers. I am working on a fix.
cubdog
banging through drywall
I just checked my amp for any noise. I can hear a very slight hum from the transformers at around 12 inches away. No sound, or hum coming from the speakers. Since I never listen to this amp from within 12 inches I'm ok with this. In a perfect world I'd prefer it to be dead quiet. But, had the topic not been brought up, I doubt I would have ever noticed.
I will say musical noise this amp is making has impressed me. Honestly, I did not buy this amp to replace any other amp that I own. It was not my intention to rebuild any system. I only bought it to provide a change of pace on occasion. I may rethink this however, I'm very pleased, beyond expectation, with the Shuguang.
cubdog
I will say musical noise this amp is making has impressed me. Honestly, I did not buy this amp to replace any other amp that I own. It was not my intention to rebuild any system. I only bought it to provide a change of pace on occasion. I may rethink this however, I'm very pleased, beyond expectation, with the Shuguang.
cubdog
cubdog
banging through drywall
raindance
Member
Shuguang S300i Mods
Update: I found a schematic for the S300i and S300MK, so I opened up the amp to make the following changes:
Add feedback on/off switch.
Remove input capacitors at the volume control (not needed)
See if I could fix the transformer mechanical hum.
Taking off the transformer cover yielded a surprise. The transformers look pretty decent, however look at the voltage on the power transformer:
From the GF website, it says:
Limited quantity in stock - only 115V for North America.
The S300I was initially made mostly for Chinese market and European market without remote control. Factory has changed the main transformers on those now offered for North America to suite 115-120V/60Hz.
I am going to check some voltages against the schematic and see how the operating points look.
Update: I found a schematic for the S300i and S300MK, so I opened up the amp to make the following changes:
Add feedback on/off switch.
Remove input capacitors at the volume control (not needed)
See if I could fix the transformer mechanical hum.
Taking off the transformer cover yielded a surprise. The transformers look pretty decent, however look at the voltage on the power transformer:
From the GF website, it says:
Limited quantity in stock - only 115V for North America.
The S300I was initially made mostly for Chinese market and European market without remote control. Factory has changed the main transformers on those now offered for North America to suite 115-120V/60Hz.
I am going to check some voltages against the schematic and see how the operating points look.
raindance
Member
It appears that the mechanical hum is exaggerated by the transformer cover which appears to be made of mild steel. It is MUCH quieter with the cover removed.
Bypassing the input caps makes a large difference. Everything seems clearer and a fog has been lifted. The caps look like Orange Drops, but I could not be sure, as I cannot see writing on them.
The effect of the feedback switch: Feedback off gives a laid back vintage 300B sound with rolled off frequency extremes and great mids. Feedback on gives a much wider bandwidth with sparkling high frequencies. There is a volume difference, the pot has to be moved from 10 o' clock to about 11 o'clock to compensate when feedback is restored.
The hum balance pots work well.
Bypassing the input caps makes a large difference. Everything seems clearer and a fog has been lifted. The caps look like Orange Drops, but I could not be sure, as I cannot see writing on them.
The effect of the feedback switch: Feedback off gives a laid back vintage 300B sound with rolled off frequency extremes and great mids. Feedback on gives a much wider bandwidth with sparkling high frequencies. There is a volume difference, the pot has to be moved from 10 o' clock to about 11 o'clock to compensate when feedback is restored.
The hum balance pots work well.