Hi All tube guru's
Need some advice, I recently purchased the yaqin MC-10L
1. The amp is rated 52 watts, is this RMS or peak.
2. I notice when i crank up the volume after about midway there is not significant
increase in volume. any ida why or is my imagination.
3. Has any one used the 10L with a magnepan MMG 4 ohm, how is the sound and is
worth buying
4. I do plan to do the mod mentioned in these forum and elsewhere, I also want to
convert the bias to a SS one using the LM337 or a equivalent regulator, is this
wishfull thinking, can any advice the pros and cons.
Appreciate if some expert out there can help, please also let me know if my post is not in the right place( am new here)
lcoelho
Need some advice, I recently purchased the yaqin MC-10L
1. The amp is rated 52 watts, is this RMS or peak.
2. I notice when i crank up the volume after about midway there is not significant
increase in volume. any ida why or is my imagination.
3. Has any one used the 10L with a magnepan MMG 4 ohm, how is the sound and is
worth buying
4. I do plan to do the mod mentioned in these forum and elsewhere, I also want to
convert the bias to a SS one using the LM337 or a equivalent regulator, is this
wishfull thinking, can any advice the pros and cons.
Appreciate if some expert out there can help, please also let me know if my post is not in the right place( am new here)
lcoelho
With tube amplifiers the output power is usually given in RMS Watts, or proper Watts as some will call it 
. None of your XXXX Watts Music Power here. Having said that, 52 Watts is I think a wee bit optimistic if you are expecting that per channel. Funnily enough it is one of the parameters I have not really bothered to check on my MC-10L, I expected at best 20 Watts per channel but did not measure the amp as it was loud enough for my dwelling space and when cranked up, normally for Pink Floyd, it certainly does not disappoint . I use a remote volume control, leaving the MC10's set at maximum but I could imagine your problem may be due to the source impedance of your signal being placed across the Yaqin's volume control. You may even find that if your input signal is on the low side then you may not be driving the amplifier enough to obtain maximum unclipped output. I have used numerous sources here ranging from Cassette and CD players, reel to reel tape decks, phono pre-amp and even a mini-disc player, all without problems as far as driving the amplifier is concerned. I am not so sure about the solid state bias though as I am led to believe that the present arrangement is self adjusting. For example, if your mains supply was to increase slightly then this would raise the B+ supply and cause the output tubes to conduct more. However, the bias voltage would also increase and to some extent would help to keep the original tube current in check. Exactly how good this is in practice would indeed make another little experiment worth while using my Variac (variable mains supply transformer) next time my amp is on the bench for its annual check over. If you regulate the bias then this counteracting effect will not happen and the tubes will be free to draw extra current.
That is what my belief is of the regulated bias argument, with auto bias this would occur naturally.
Hope this helps, sorry I have no practical experience of the speakers you mention, I am using dual concentric drivers with a sensitivity of 92dB and the sound stage is fantastic. Police sirens on the TV sound, when fed through the Yaqin, often fools me and has me going to the window... I have also had visitors reaching for their mobile phones when it was one on the TV that was ringing. Often we laugh here about such things, the sound is so natural and full of presence in the room. I never achieved anything like that with SS amplifiers though I suppose some will say you can but I think would cost much more than my humble (cost wise) system here. Having gone back to Tubes I think I will stay with them now until the grim reaper comes for me
. None of your XXXX Watts Music Power here. Having said that, 52 Watts is I think a wee bit optimistic if you are expecting that per channel. Funnily enough it is one of the parameters I have not really bothered to check on my MC-10L, I expected at best 20 Watts per channel but did not measure the amp as it was loud enough for my dwelling space and when cranked up, normally for Pink Floyd, it certainly does not disappoint . I use a remote volume control, leaving the MC10's set at maximum but I could imagine your problem may be due to the source impedance of your signal being placed across the Yaqin's volume control. You may even find that if your input signal is on the low side then you may not be driving the amplifier enough to obtain maximum unclipped output. I have used numerous sources here ranging from Cassette and CD players, reel to reel tape decks, phono pre-amp and even a mini-disc player, all without problems as far as driving the amplifier is concerned. I am not so sure about the solid state bias though as I am led to believe that the present arrangement is self adjusting. For example, if your mains supply was to increase slightly then this would raise the B+ supply and cause the output tubes to conduct more. However, the bias voltage would also increase and to some extent would help to keep the original tube current in check. Exactly how good this is in practice would indeed make another little experiment worth while using my Variac (variable mains supply transformer) next time my amp is on the bench for its annual check over. If you regulate the bias then this counteracting effect will not happen and the tubes will be free to draw extra current.That is what my belief is of the regulated bias argument, with auto bias this would occur naturally.
Hope this helps, sorry I have no practical experience of the speakers you mention, I am using dual concentric drivers with a sensitivity of 92dB and the sound stage is fantastic. Police sirens on the TV sound, when fed through the Yaqin, often fools me and has me going to the window... I have also had visitors reaching for their mobile phones when it was one on the TV that was ringing. Often we laugh here about such things, the sound is so natural and full of presence in the room. I never achieved anything like that with SS amplifiers though I suppose some will say you can but I think would cost much more than my humble (cost wise) system here. Having gone back to Tubes I think I will stay with them now until the grim reaper comes for me
I just googled it and they state that it improves the sound dramatically, more linear is what they suggest is happening
I wouldn't try it without consulting my designer friend first...
Though I'm interested what you think costis?
Part 1 DECWARE - The Hazen Mod
Part 2 http://www.decware.com/newsite/paper146.html
I assume this is the mod.
I wouldn't try it without consulting my designer friend first...
Though I'm interested what you think costis?
Part 1 DECWARE - The Hazen Mod
Part 2 http://www.decware.com/newsite/paper146.html
I assume this is the mod.
Mmmm...nobody seems to have an explanation and I am usually pretty hopeless at coming up with theories. However here are two for what it is worth, anybody else have one?
1) Is it possible that a very small amount of positive feedback is being applied, hence the apparent lift in certain areas of the audio spectrum?
Does this sound plausible or rubbish? A large signal is applied to the tubes grid causing a steep rise in tube current. More secondary electronics are reflected from the Plate to the suppressor but because it is no longer connected to cathode, attains a small negative charge. This negative charge is transferred by the capacitor to the cathode causing the grid to appear more positive - hence positive feedback. The levels concerned are not large enough to cause oscillation.
oh well!
Theory 2) Fitting a capacitor between suppressor and cathode effectively reduces the capacitance between plate and the earthy suppressor/cathode connection. Cannot really see this as any kind of argument at audio frequencies though.
Food for thought though...has this so called mod caused the Pentode to behave like a tetrode? i.e. has a kink (even small) returned in the tubes characteristic?
This does appear to be one of those mods that cannot be proven using instruments and only detectable using the lug hole. At $100 a throw I wish I could convince a lot of people about this!
Les
1) Is it possible that a very small amount of positive feedback is being applied, hence the apparent lift in certain areas of the audio spectrum?
Does this sound plausible or rubbish? A large signal is applied to the tubes grid causing a steep rise in tube current. More secondary electronics are reflected from the Plate to the suppressor but because it is no longer connected to cathode, attains a small negative charge. This negative charge is transferred by the capacitor to the cathode causing the grid to appear more positive - hence positive feedback. The levels concerned are not large enough to cause oscillation.
oh well!
Theory 2) Fitting a capacitor between suppressor and cathode effectively reduces the capacitance between plate and the earthy suppressor/cathode connection. Cannot really see this as any kind of argument at audio frequencies though.
Food for thought though...has this so called mod caused the Pentode to behave like a tetrode? i.e. has a kink (even small) returned in the tubes characteristic?
This does appear to be one of those mods that cannot be proven using instruments and only detectable using the lug hole. At $100 a throw I wish I could convince a lot of people about this!
Les
Yesterday i adjusted my bias to 0,350V after warming up for 10 min, values were all under 0.3v before adjusting.
All was fine after adjusting, listeing to some music sounded nice (as always).
But after that session I turned of the amp, and later that I evening I turned the amp back on. It started warming up, until after say 20 sec the fuse (not in the back of the ) but in my central fuse box.
I tried the adjustmend again, now setting the value to 0,300 V, after turning the value very low. All seemed fine, but now it happened again
Should I go lower? Or should I check something else? Should I maybe suspect my multimeter?
All was fine after adjusting, listeing to some music sounded nice (as always).
But after that session I turned of the amp, and later that I evening I turned the amp back on. It started warming up, until after say 20 sec the fuse (not in the back of the ) but in my central fuse box.
I tried the adjustmend again, now setting the value to 0,300 V, after turning the value very low. All seemed fine, but now it happened again
Should I go lower? Or should I check something else? Should I maybe suspect my multimeter?
Are you talking about the fuse box in the house/apartment? if so I would look elsewhere other than the amp, adjusting the bias in the amp from .3mv to .35mv in my mind couldn't trip or blow a house fuse, unless the circuit in the house is on the very ragged edge of It's limits with all that's in use and then it would be getting tripped all the time by other appliances.
Or are you talking about in the amp?
I have never seen any fuses in the circuit of the Yaqin apart from the one in the IEC socket
Or are you talking about in the amp?
I have never seen any fuses in the circuit of the Yaqin apart from the one in the IEC socket
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Yes, in my house. It is related to my adjustments since it does not happen when I do not turn on the amp. Also, when I turned down the voltage to very low values, I was able to power it up again. So, it must have something to do with my adjustments?
I did try to power it up again after my adjustments, I did not have the problem. The difference however was that the amp was already warmed up.
A fuse is located in the IEC connector, but this one is not blown.
Actually, it was not a fuse that was blown, but the RCD was triggered. My Amp is not grounded from the IEC inlet btwI noticed when I opened the housing.
The voltage where I live (Netherlands) is approx 230V.
I did try to power it up again after my adjustments, I did not have the problem. The difference however was that the amp was already warmed up.
A fuse is located in the IEC connector, but this one is not blown.
Actually, it was not a fuse that was blown, but the RCD was triggered. My Amp is not grounded from the IEC inlet btwI noticed when I opened the housing.
The voltage where I live (Netherlands) is approx 230V.
With the larger caps I couldn't find anything better that would fit, but the 22uf caps can be replaced with Jensen's, I think they will fit and are a very good cap. Have a look anyway, they may have something to fit Tobias Jensen Production A/S - Radial electrolytic capacitor, screw terminal looks like they have 220uf/400v radial caps that are 035x054 in size, might like to see if that is similar to the larger ones in it Tobias Jensen Production A/S - Radial electrolytic capacitor, solder terminal
Space is a big problem with this amp if wanting to upgrade some parts.
Benefits can come from upgrading the 0.1uf coupling caps and the resistors in the signal path too.
Though the main thing is to make it safe.
Space is a big problem with this amp if wanting to upgrade some parts.
Benefits can come from upgrading the 0.1uf coupling caps and the resistors in the signal path too.
Though the main thing is to make it safe.
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Normally RCD's operate if there is a leak to earth but as you do not have an earth on the amplifier itself, perhaps there is a leak to chassis then to earth via other equipment that is plugged into the amplifier inputs? Adjusting the bias from 0.3V to 0.35V should not cause the RCD to operate. Can you use your multimeter to do a resistance check between the metal chassis and the mains input connector of the amplifier, just to confirm there is no leak to chassis from either of the input pins. With respect to the capacitors, I obtained some spare ones manufactured by EOS, their type number is B43504-A2477-M, if you can still get them.
Good to see this Amp still having its followers
Hope you can fix the RCD problem. Sounds like it may need looking at by a professional. They don't seem to be the most reliable of beasts and it always seems to come from the adjustable bias?
BTW I took my partners son's nano iPod and connected it to the 10L on the weekend while they were visiting my apartment. Turned it up. We listened for a while (through quite basic Kenwood home theatre speakers). We went to her place. A little while later he said "I want one of those things". I said you mean the Amp? He said yes as it sounds so good. Even my partner separately said (while listening to her budget ipod doc with the same nano) "Your system sounds so much better". Later Mr. 12 looks at my high quality headphones and drools. Looks like I have some budding audiophiles.
We are about to buy a bigger house and I need to drive some (base level) Magnepan speakers in the theatre room so I guess I am shopping for a KT88 amp in the same vein. Any recommendations based on the fact I love the stock standard Yaqin 10L? I know the Magnepans need huge watts/currents so will a KT88 power them enough or am I looking at something bigger? I dont want to go to transistors or Class D. I just don't like the sound.
I need to strike while the iron is hot and Christmas approaches...
Hope you can fix the RCD problem. Sounds like it may need looking at by a professional. They don't seem to be the most reliable of beasts and it always seems to come from the adjustable bias?
BTW I took my partners son's nano iPod and connected it to the 10L on the weekend while they were visiting my apartment. Turned it up. We listened for a while (through quite basic Kenwood home theatre speakers). We went to her place. A little while later he said "I want one of those things". I said you mean the Amp? He said yes as it sounds so good. Even my partner separately said (while listening to her budget ipod doc with the same nano) "Your system sounds so much better". Later Mr. 12 looks at my high quality headphones and drools. Looks like I have some budding audiophiles.
We are about to buy a bigger house and I need to drive some (base level) Magnepan speakers in the theatre room so I guess I am shopping for a KT88 amp in the same vein. Any recommendations based on the fact I love the stock standard Yaqin 10L? I know the Magnepans need huge watts/currents so will a KT88 power them enough or am I looking at something bigger? I dont want to go to transistors or Class D. I just don't like the sound.
I need to strike while the iron is hot and Christmas approaches...
I seem to have fixed it
The amp was grounded after all (did not examine it well), I added the extra resistors for the caps, and replaced the pre amp tubes with russion 6N1P-EV-OC (voshkod) and now all is fine again
Better then before I would say, I think these new tubes sound better than the original tubes I had
The amp was grounded after all (did not examine it well), I added the extra resistors for the caps, and replaced the pre amp tubes with russion 6N1P-EV-OC (voshkod) and now all is fine again
Better then before I would say, I think these new tubes sound better than the original tubes I had
Hi, I'm new to this whole "forum" thing but as a MC10L owner need some help and hope to find some here. My amp is as good sounding as I'd hoped - I've already got a MENG EL 84, which I love - but between 5mins and and hour of switch on the left channel fails - it sounds like the input has earthed, the same sound you get when you touch the and of a jack plug connected to a guitar amplifier, but louder. After being switched off for 30 secs everythings back to perfect!? Anyone out there got a suggestion please??