Just a little update.
The silibus has gone now, needed more burn-in I guess.
I replaced the other resistors in the signal path also. The sound is smooth and layed back, maybe a little too layed back for my liking so I'm looking at replacement caps for the power supply and hoping to incress the amount of attack.
The silibus has gone now, needed more burn-in I guess.
I replaced the other resistors in the signal path also. The sound is smooth and layed back, maybe a little too layed back for my liking so I'm looking at replacement caps for the power supply and hoping to incress the amount of attack.
Hi data,
I have a mc10l and a set jj el34 an a set jj KT77. The KT77 sound cleaner mid and tighter at low frequency as the EL34.
I Have vintage mullard ecc85 used in the phase splitter it gives push to the low frequency only high become a bit harsh.
Now i have 6n1eb Russian military speck 6n1.
Have fun.
I have a mc10l and a set jj el34 an a set jj KT77. The KT77 sound cleaner mid and tighter at low frequency as the EL34.
An externally hosted image should be here but it was not working when we last tested it.
I Have vintage mullard ecc85 used in the phase splitter it gives push to the low frequency only high become a bit harsh.
Now i have 6n1eb Russian military speck 6n1.
Have fun.
Hi Helmuth 
I nearly tried out some JJ KT77's but instead went with Svetlana Winged C's, the sound is very balanced to my ears. I'm also using the Russian 6N1's in the driver stage.
I can't remember if I have mentioned that with this amp Triode strapped the difference between power valves is less than when it was running in UL mode.
I may try the JJ's some time in the future
Cheers.
I nearly tried out some JJ KT77's but instead went with Svetlana Winged C's, the sound is very balanced to my ears. I'm also using the Russian 6N1's in the driver stage.
I can't remember if I have mentioned that with this amp Triode strapped the difference between power valves is less than when it was running in UL mode.
I may try the JJ's some time in the future
Cheers.
Just recieved my MC10-l this morning
Hi, Interesting discussion. I purchased one of these new off a seller on you know where about 6 weeks ago and had it shipped to Sydney, Australia by Sea... Cheap, cost $360 including freight and that was for a 240 volt model. Arrived this morning. I assembled it and then went to work. Am about to go home and bias it. My first ever amp was a mono one pulled out of my parents old radiogram. Man that could go loud. I am going to try the Yaqqie this evening with my old Kenwood home theatre speakers. This will do until I can biamp with another Yaqin or perhaps a class D Amp/T-amp to my Magnepan MMG's. I will review it later this evening. Here's hoping I got a good one...
Andrew
Hi, Interesting discussion. I purchased one of these new off a seller on you know where about 6 weeks ago and had it shipped to Sydney, Australia by Sea... Cheap, cost $360 including freight and that was for a 240 volt model. Arrived this morning. I assembled it and then went to work. Am about to go home and bias it. My first ever amp was a mono one pulled out of my parents old radiogram. Man that could go loud. I am going to try the Yaqqie this evening with my old Kenwood home theatre speakers. This will do until I can biamp with another Yaqin or perhaps a class D Amp/T-amp to my Magnepan MMG's. I will review it later this evening. Here's hoping I got a good one...
Andrew
Sadly it sits dead on the living room floor. Suspected el34b fault. Turned on but made hum, thumped and banged from one channel. Tube got very hot. Changing tube to other side resulted in same behaviuor from other channel and same tube got hot so must be tube... Bad luck I guess...
Hi atsc,
the same thing happened to me after I first got the Yaqin, crackles, lightinenig and blown fuse. Left channel dead, bias resistor and some caps blown, after replacing blown parts and installing russian 6n1-evs and 6P3S-evs tubes it has been running like a charm for over a year 5+hours daily average. The blue LED are gone, it has a lwering of the bias effect, other than that the amp is sturdy, with a powerful, thick sound character. I love it.
Do not lose heart, get it fixed and you'll be happy.
cheers!
the same thing happened to me after I first got the Yaqin, crackles, lightinenig and blown fuse. Left channel dead, bias resistor and some caps blown, after replacing blown parts and installing russian 6n1-evs and 6P3S-evs tubes it has been running like a charm for over a year 5+hours daily average. The blue LED are gone, it has a lwering of the bias effect, other than that the amp is sturdy, with a powerful, thick sound character. I love it.
Do not lose heart, get it fixed and you'll be happy.
cheers!
Thats is a shame it spoiles the fun.
I buy mine second hand but the man who bought it by ebay in china became it home with a bumped backside.
It was fallen at transport. He received a new backplate from china later was nice solved.
It is very heavy and has to come from far and tubes have to be treated with care. Hopefully you get it running fast.
I buy mine second hand but the man who bought it by ebay in china became it home with a bumped backside.
It was fallen at transport. He received a new backplate from china later was nice solved.
It is very heavy and has to come from far and tubes have to be treated with care. Hopefully you get it running fast.
I have ordered 2 new tubes off ePray. I smelt something as the tube heated also the bias seemed awry as I watched it climb on both channels. I will remove all tubes and test the voltages as per your guide this evening. Is that the correct way to proceed??? I already swapped the suspect tube to other side to confirm it was a tube issue. I will change both V3 and V4 just in case...
I can build solid state Amps from Kits (or did in the 80's) and used to own a nice Tube Stereo Reciever so can likely carry out the work myself I just never really had acccess to circuit diagrams before so didn't try...
BTW what range should I set my multimeter to if measuring Bias (do I use Amps or Volts?) and what would it then read?
Thanks in advance...
Andrew
(Who is not giving up!)
You will measure millivolt over the 10 OHM resistor(U=IxR=>U=0,026x10=0,26V) I Have set mine to 260mV=26mA through the tube save value.
I had problems blowing a tube at a higher bias 350mV so do do not advise that.
You have to set the bias for all four tubes separately.
Thank you Helmuth,
Hmmm... That is what I thought. I was getting readings in the ~ 3.5 volts range and climbing - not millivolts :-( I will check how I read the meter to make sure i don't need to read the display differently, but I doubt it. I had it set to the 20 volt range I think. I wont try measuring again with a dead tube. I'll yank them and test the voltages on the socket. BTW can someone confirm this is what you do to test a tube amp? Solid State don't use transister sockets... I'm confused!
Thanks
Andrew
First measure when the amp is off, if the 10 Ohm resistor still is 10 Ohm.
I think it is broken and now a much higher resistance and therefor the voltage you measure is to high.
Thank you Helmuth that is a good tip. It measures 10.5 on the blown side and 10.1 on the good side. Within tolerance?
Now I am guessing I should take all el34b's out and turn on and measure voltages at sockets. Do I also remove the 6n1p's as I do this test? I don't want more issues...
Andrew
Now I am guessing I should take all el34b's out and turn on and measure voltages at sockets. Do I also remove the 6n1p's as I do this test? I don't want more issues...
Andrew
BTW anyone know if there are differences in those MC10ls that have pretty wording on the transformer cans and those that don't. Mine doesn't have the words. Luckily it does seem to be a 240 volt version for Aus conditions. BTW someone asked earlier about the seller. You can find him under dpihkg on ebuyandpray web site. So far he was slow to post but this was special order I presume plus Christmas delays were a problem. But he delivered at a bargain price and even followed up the blown tube with a free one! So read his feedback carefully but so far my experience despite the technical hitch has been positive with this seller.
Les notes in his paper NOT to power up these amps with all the tubes removed! The reason being that you will get a rise in voltages elsewhere, you need to leave the ones in on the working channel..........If I remember correctly.
If It's indeed a 240v power transformer it will have "240" stamped on the top of the transformer itself (not the cover),
in case you want to check.
Take your time and double check on what you need to be doing, be carefull and best of luck with the amp.
Ian.
If It's indeed a 240v power transformer it will have "240" stamped on the top of the transformer itself (not the cover),
in case you want to check.
Take your time and double check on what you need to be doing, be carefull and best of luck with the amp.
Ian.
It's alive!
Good news, two new tubes, a careful read of les' doc, a multimeter and some careful testing and it is working again. Interestingly I only measure 428 volts not 450 for the ht. Main transformer gets warm but it is from the tubes next to it. So it looks like it really is a 240 volt version.
Does anyone know the input sensitivity. Volume is a bit low. But I have only tested a bluray player and I have never used that before except through hdmi. anyway I am surprised by the lack of hum and noise. I guess going back 30+ years these things always hummed.
Anyway my thanks to you all. Without your help it would still be a dead duck... Can't wait till I can get this together with my Magnepan MMG's...
P.s. What is the story on the new mc10t.
Good news, two new tubes, a careful read of les' doc, a multimeter and some careful testing and it is working again. Interestingly I only measure 428 volts not 450 for the ht. Main transformer gets warm but it is from the tubes next to it. So it looks like it really is a 240 volt version.
Does anyone know the input sensitivity. Volume is a bit low. But I have only tested a bluray player and I have never used that before except through hdmi. anyway I am surprised by the lack of hum and noise. I guess going back 30+ years these things always hummed.
Anyway my thanks to you all. Without your help it would still be a dead duck... Can't wait till I can get this together with my Magnepan MMG's...
P.s. What is the story on the new mc10t.
It's alive!
I am thinking of building this. Does it make sense to use this between a cd and a mc10l?
http://secure.oatleyelectronics.com/files/k295notes.pdf
I am thinking of building this. Does it make sense to use this between a cd and a mc10l?
http://secure.oatleyelectronics.com/files/k295notes.pdf
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Not so sure about this.The kit makers admit to the fact that the kit suffers from micro-phony unless steps are taken to reduce this. This could taint the sound and also you are putting two more coupling capacitors into the overall circuit. I have had no problems driving my MC-10L from various sources which include DVD and CD players, audio from cable TV box and indeed the TV itself. Also my old skool Cassette and reel to reel tape decks come through well good as does my home made phono Amp/RIAA EQ box. Even an iPod has been coupled up at some time when the lads came round one evening. Best part of this post would be to get feedback from someone who has already built and tried this buffer amplifier.