Bought a Yaqin MC10T valve amp

I ended up getting a Yaqin MC10T 3 months ago based on the many good reviews of the 10L, both on here and elsewhere on the net, marking my entry into tube audio. It powers some Sony SS-F6000P speakers (which I hope to replace with Bowers & Wilkins 683 S2's when i save enough).

The stock Shugang valves sounded great once burned in, with a particularly good 3D sound stage although perhaps a little rough sounding. Still great compared to my Denon SS amp though. I've done a bit of tube rolling since then and rolled the following tubes:

12AX7 spot:

Current production Shugang 12AX7 which came with the amp
Mullard Reissue
Tung Sol reissue
Electro Harmonix reissue
60's production Baldwin branded Matsushita 12AX7 Long Grey Plates - O getter
60's production Canadian Made Amperex Bugle Boys (Westinghouse branded)
'63 production RCA Grey Plates - O Getter
50's production Raytheon 12AX7 Long Black Plates

12AU7 spot:

Current production Shugang 12AU7 which came with the amp
'57 production Raytheon Black Plate 6414's

EL34 spot:
Current production Shugang EL34 which came with the amp
Current production Svetlana EL34b's
Current Production JJ 6CA7 "Fat Bottles"
Soviet era 6P3S-E "coin base" tubes

I still have some valves on the way to try, though the current setup already sounds so amazing that I can't really see how anything short of a new set of speakers can improve upon anything.

Valves on the way are:
50's production 12BZ7 Long Black Plates with D getter
Soviet production 6N2P-EV's + socket adaptors

The current configuration I'm running is as follows:

Raytheon 12AX7 Black Plates in the 12AX7 spot, Raytheon 6414's in the 12AU7 spot and Current production JJ 6CA7's in the EL34 spot. This seems to give an incredible amount of detail with nice even lows, mids and highs.

The JJ 6CA7's are scooped, or a little lacking in the mid range but with excellent lows and high's which made other tubes in the pre section with stronger mids sound particularly good without it being overpowering. I quite enjoyed the Matsushita's with these though the Raytheon Blackplates were noticeably more detailed without being an overpowering presence in the midrange. The Amperex Bugle Boys sounded similar to the Matsushita's.

The Raytheon 6414's were so good in the 12AU7 spot I didn't bother going looking at other tubes for this position and ordered more as spares. Nice and tight, low noise and good right through the range.

Mullard Reissue 12AX7 + Raytheon 6414's + Svetlana EL34b's were a nice detailed combination but seemed to lack the 3D stage / presence. Sounded more like a particularly nice recording (which it was) rather than actually being there in the audience. More detailed than the stock Shugangs but less 3D, still much better than my Denon SS amp though.

I did try the Soviet 6N3PS-E's and found them neutral and closed sounding, though to be perfectly honest I didn't even wait for them to warm up properly let alone burn in. It's just that the JJ 6CA7's sounded so amazing after burning in that I couldn't handle them. I'll give them another try down the track. My understanding is that they take some time to burn in.

I'm hoping that the 12BZ7's or 6N2P-EV's are as good or pretty close to the Raytheon 12AX7 Plack Plates once I try them. I only have the 1 pair of the Raytheon Black Plates, and they're quite expensive/hard to find compared to the other two. The 12BZ7's work out to $25 each and the 6N2P-EV's about $5 each so if they work well I'll stock up on them. I know the 12BZ7's are meant to be somewhat microphonic due to the long plates, though hoping some tube dampers will help with that.

Now to try supress the tube rolling bug which seems to keep biting me.... I need to save for better speakers dammit! :tongue:

Since getting this amp its caused me to listen to other types of music rather than just my usual 60's-90's rock. I'm finding country and jazz music sounds incredible. Listen through my Denon and its very "Meh, put something else on". Through the Yaqin its actually very interesting and easy to listen to music. Valves really bring out the detail of instrumentation far more than solid state. Wind instruments have a "breathiness" to the notes which I love, same goes for vocals. Go figure.

You are officially hooked on bottles

Sounds like you are really enjoying this stuff :thmbsp:

Yeah, every change brings a little difference. Some subtle and other not so subtle, and no two quite alike..... Addictive. I have to say, I've become a bit of a fan of anything black plate. Everything I've tried which has black plates sounds fantastic. :thmbsp:

I've not really figured out how to bias it correctly however. My voltages seem to go all over the place. I've settled for getting matched quads on the power tubes and simply setting the BIAS pots half way. All my pre tubes are matched as well, although I know its not necessary. It still sounds fantastic. :yes:

My amps started life as a 10l, although only the transformers are from the original unit.

I would stress to you to get the bias as right as possible, matched quads aren't going to compensate here, the bias pots are a single turn type and some can be very touchy and will act erratic in some areas of their turn.

Be patient and see if you can manage it.

It will mean that some of those nice tubes will last longer, and a correctly biased stereo amp will present a much better sound stage as well

A half way setting on those will be a different setting from one to the next pot, from my experience.

Cheers

I'll have to try again on the weekend. See if after a few hours play the voltages stabilize. Isn't it primarily just the power tubes which are affected reliabillity wise by this?

try the EH 6CA7 -

loonze said:

try the EH 6CA7 -

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Is it actually an improvement over the JJ 6CA7? The JJ is incredible value for money. Most likely out of the same plant as other New Sensor tubes like the EH..... :scratch2:

Many of us know the feeling. I tried TRA (tube rollers anonymous) but they were just a group of enablers. Glad you're enjoying it!

mjw21a said:

I'll have to try again on the weekend. See if after a few hours play the voltages stabilize. Isn't it primarily just the power tubes which are affected reliabillity wise by this?

Click to expand...

Yes, the power tubes.

When you get the stereo balance right via biasing close to spot on, and that sound-stage snaps into how it should be....you will love it even more

I bought a used M13-S. Is the schematic for the 10 the same as the 13?
Love the way this thing sounds --- after 40 yrs of solid state amps this is my first tube
amp. And what an eyeopener this cheap tube has been.

My understanding is that the 13 is the same as the 10 except with a VU metre and remote control.

Yes, going to have to figure out this BIAS business. I don't want to have the power tubes constantly blow. Only 3P6S-E tubes are cheap enough to do that with at $14 per tube.

Check the plates on the power tubes for red plating, have a look for a red glow on the plate structures in a dark room.

Looks like this..

If you have this, lower the bias on that one, or any showing signs.

Edit: Of course always be careful around high voltages, like when biasing.

Yeah, I've already done that. I actually caused one to red plate last time I tried to adjust BIAS. They're all a fair way under that presently. I read one one forum to aways keep one hand grounded while doing this for safety reasons...


I'm thinking if they work, they might be the go for tubes with known microphonic issues like the 12BZ7's

mjw21a said:

Yeah, I've already done that. I actually caused one to red plate last time I tried to adjust BIAS. They're all a fair way under that presently. I read one one forum to aways keep one hand grounded while doing this for safety reasons...


I'm thinking if they work, they might be the go for tubes with known microphonic issues like the 12BZ7's

Click to expand...

Keeping hand grounded while working with live circuit is alomost sure way to kill yourself. You should keep one one hand behind your back, so that you will not touch circuit with both hands at the same time. Keep in mind that "ground" is still part of circuit!

Very! good advice above ^^^^^

Just try silicon O Rings, two on each tube where the internal supports contact the inside of the glass envelope.
Can help with mechanically noisy tubes.

A lot cheaper way to try too.

Ok, I'll try the silicon rings on those. Have just ordered 10 for $5. I'll keep in mind not to touch anything while adjusting bias now too. I've been lucky it would seem....

Keen on trying these 12BZ7 Black Plates. Anything Black Plate seems to give some extraordinary sound. I understand they have 30% more gain than 12AX7 tubes too which should be welcome providing this translates to even more apparent volume.

Really incredible the volume put out by this amp considering it's only 45W out per channel. More is always nice though :guitar:

mjw21a said:

I understand they have 30% more gain than 12AX7 tubes too which should be welcome providing this translates to even more apparent volume.

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They have the same amplification factor as a 12AX7 (100). Increasing the gain in the preamp stage of your amp isn't going to give your more power, although it may have more volume relative to the position of the knob.

jeff

vinylkid58 said:

They have the same amplification factor as a 12AX7 (100). Increasing the gain in the preamp stage of your amp isn't going to give your more power, although it may have more volume relative to the position of the knob.

jeff

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That'll do nicely I think. :thmbsp:

Has anyone else here tried them? How do they sound?

don't want to hijack the thread ,but I got me the same amp ( first tube amp ever)pushing some totem Sttaf and the sound is really good , today I got in the mail some EH 6CA7 that I want to install, now my question is : Do I need to adjust the bias? and to what? and have no clue on how to do it.... I am reading and trying to learn as much as I can, but figured I ask you Gents.