You only need to pull V2 if it is the left channel you have problems with. If the hum goes the problem is probably in the pre-amp. If it is still there then maybe you have a problem in the output stage or the coupling.
What are the bias voltages on the two left channel EL34's? They should be more or less the same at around 0.35V as measured across the 10 Ohm bias measuring points.
Ohhh... so that's all it was lol. I didn't touch the bias... Yep on that side I got readings of 0.08 and 0.67. So now the fun of putting the new caps back in 😉
Thanks Les
Does anyone know the value of the potentiometer ?
I want to replace it with a motorised one. Hificollective offer 20K or 50K alps blue dual gang. But other values are available from elsewhere.
I want to replace it with a motorised one. Hificollective offer 20K or 50K alps blue dual gang. But other values are available from elsewhere.
Pot is 20k. You should be able to find the schematic with a Google search. If you can't find it send me a PM.
You may find this interesting:
http://homepage.ntlworld.com/lez/YAQIN MC10/A LOOK AT THE YAQIN MC10L.pdf
You may find this interesting:
http://homepage.ntlworld.com/lez/YAQIN MC10/A LOOK AT THE YAQIN MC10L.pdf
Thanks, 20k 😉
I have just realised that hificollective are asking £100 for the pot + receiver..... 😡
I have just realised that hificollective are asking £100 for the pot + receiver..... 😡
Time for a little rewire of the signal cables. Straight forward enough, however the ones leaving the preamp board to power stages are 3 core. Can someone explain this and also identify the connector types please so I can get more of them 🙂
At your service.
Usefull link: http://www.cathedralspeakers.com/yaqin
An externally hosted image should be here but it was not working when we last tested it.
Usefull link: http://www.cathedralspeakers.com/yaqin
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Wow, there's a lot of work to do. Do they really have 130V cathode to heater for the 6N1? Unbalanced phase splitter? A quasi-SRPP (badly unbalanced) input stage?
Wow.
Wow.
hum on right channel speaker
Newbie in tubes here>>
This is great thread and forum for Yaqin MC10-L. I have a unit that is about 3 months old and IT DEVELOPED A HUM ON THE RIGHT CHANNEL. I can still hear the music but the hum is there..i checked the bias on V2 and it was 0.06v)
i contacted the seller for help and was told to do the ff:
Move V1 to V2 socket and if there is bias the problem was V2 (EL34).
my questions:
1.is this check enough to isolate that the issue was V2 (l34)? I ordered new ones and on the way..from CAnada..
2. When i put V1 to V2 how long do i have to wait to make a reading? seller says within 3 minutes? is this right?
thanks in advance!!!
Audio0412
Newbie in tubes here>>
This is great thread and forum for Yaqin MC10-L. I have a unit that is about 3 months old and IT DEVELOPED A HUM ON THE RIGHT CHANNEL. I can still hear the music but the hum is there..i checked the bias on V2 and it was 0.06v)
i contacted the seller for help and was told to do the ff:
Move V1 to V2 socket and if there is bias the problem was V2 (EL34).
my questions:
1.is this check enough to isolate that the issue was V2 (l34)? I ordered new ones and on the way..from CAnada..
2. When i put V1 to V2 how long do i have to wait to make a reading? seller says within 3 minutes? is this right?
thanks in advance!!!
Audio0412
I was going to say that the apparently "unbalanced" phase splitter was an attempt to correct for the lack of a CCS tail, but then I noticed that the anode resistors were the wrong way round so they increase imbalance rather than correcting it. Either a mistake or an attempt at 'euphonic' distortion.SY said:
The "quasi-SRPP" looks like the designer could not decide whether to do a proper SRPP or a proper mu follower, so just left it as an unbalanced SRPP - which will be worse than either of them! Given the relatively high impedance load a simple active load stage would be just as good, but Chinese designers do like the SRPP and audio buyers seem to like it too.
The output grid resistors are quite low in value so will load the LTP and increase distortion. Maybe low values are needed to cope with gassy Chinese valves?
Thing is though, this amp already sounds very good...good enough that I'm sure my 46 year old ears would fail to differentiate it from my $1500 ss amp in a blind test. Why not simply enjoy it as is?
Recently had a Krell amp here, the Krell won*, just, by its articulate upper bass. Then I upgraded the caps in the 10L, made a staggering difference. Now prefer the 10L any day.
*My speakers are an easy load to drive, so the Krell would have come into its own with different speakers
*My speakers are an easy load to drive, so the Krell would have come into its own with different speakers