[Vapor Audio]

Hey guys, finally got some tube gear coming my way ... a Chinese Integrated, Yaqin MC-10L like this

http://cgi.ebay.com/YAQIN-MC-10L-MC10L-Integrated-Tube-Amplifier_W0QQitemZ370097706772QQcmdZViewItem

Also got a schematic for it, so let the modding begin!  Just wondering what tubes to try in it first?  Would some Svetlana EL34's be a choice?

[Vapor Audio]

Come on STL guys, help a tube n00b out ... Chris gave me suggestions in a PM, the rest of you suck 

[woodsyi]

Hard to beat these. 



http://www.audiocircle.com/index.php?topic=61221.0

Hate to break up a matched octet but you will have a back up quad. 

[Vapor Audio]

Well, they may be great tubes ... but a set of 4 would cost as much as I paid for the amp 

How about suggestions on a Quad that's under $150.  Chris suggested the SED Winged C EL34's.

[steve k]

I second the SED's. They're probalby the best overall sounding new EL 34 made. Sweet highs, mids to die for and full bass. Other new brands: Sovtek, EH, JJ etc. tend to tip up the highs or punch up the bass at the expense of the midrange IMO. And it's the midrange that makes the EL34 such a special tube.
steve

[Bob in St. Louis]

the rest of you suck 

Not as good you blow. 

I have two sets of EL34 you can play with*. One is Groove Tube, the other escapes me. The age is unknown.
These, by the way are the ones I mentioned to you last night about taking to Scott's to have their happy level checked on his happy level tester.

As far as what tube delivers what sonic change, well....You can wait for more people that suck to come along.
So there. I've bumped your thread with some valuable information AND an offer to borrow my stuff. Be-otch. 

Bob

*one set at a time of course.

[Vapor Audio]

the rest of you suck 

Not as good you blow. 

I have two sets of EL34 you can play with*. One is Groove Tube, the other escapes me. The age is unknown.
These, by the way are the ones I mentioned to you last night about taking to Scott's to have their happy level checked on his happy level tester.

As far as what tube delivers what sonic change, well....You can wait for more people that suck to come along.
So there. I've bumped your thread with some valuable information AND an offer to borrow my stuff. Be-otch. 

Bob

*one set at a time of course.

Haha, bad day at the office Bob?  Lemmie guess, that Saaaab owner with the dead blower motor and windows stuck down raised hell this morning 

Hey, anybody know anything about the 6N1's that are used in this amp?  Are those worth experimenting with, or are the output tubes where any sonic changes come from? 

I can already tell I'm gonna hate getting into tubes.  I'll have mounds of catelogued tubes stacked next to my mounds of drivers in a few months.

[Bob in St. Louis]

Haha, bad day at the office Bob?  Lemmie guess, that Saaaab owner with the dead blower motor and windows stuck down raised hell this morning 

No, they didn't come in......It was raining this morning. 

Don't forget about modding the caps too. 

Baaaab at Saaaaab 

[electricbear]

Even though you say we suck I'll rise above you with a response.
Give Michael at www.vacuumtubes.com a call. He's in St Charles, maybe he'll let you borrow some for a weekend.

[Scott F.]

Since I don't suck I'll offer up a few suggestions and observations on your new amp.

First, your input tube the 6N1 has a few variants, namely the 6DJ8, 6922, 6H30, 7308 and possibly a few others that might work.

After looking at your amp, I see that it has an adjustable bias. That opens it up to a world of output tube possibilities, not just EL-34s. Some will work and sound better than others but having an adjustable bias lets you play with EL34s, 6L6s, 5881s, KT88s, KT90s and if you want to spend some serious money Genelex KT66s. Before anybody out there jumps in a says X tube won't work in this circuit because it was designed for Y tube....I know. Electrically it shouldn't damage the amp or tubes. Each tube will sound different due to changing the operating characteristics of the circuit. Some will work and sound better than others. And yes, I know that the output transformers were picked and the circuit optimized for (apparently) the EL34 but other tubes (if biased properly) will work.

If you want to listen to some JJ and SED EL34s, I can loan you a quad. I've also got some EH KT88s you can try plus I think I have a quad of RCA 6L6s and a few 6DJ8s you can try.

After looking a schematic of your amp (if I have the most current one) I see some easy mods you can do to make it more resolving. The coupling caps are .22s. Easy, go for some teflons. Then the grid stop resistor is a 1k. Go for a 1w Tantelum. Also the feedback resistor is a 5k1 bypassed with a 100pf cap. A tant would be nice there along with a nice poly cap (believe it or not, the feedback parts make a difference in the sound). The B+ power supply could use some work. It is rectified but it has minimal filtering (C only, not CLC) which means you'll have a fair amount of ripple (noise). Same goes for the 6.3 volts fed to your driver tubes (completely unfiltered). We need to take a look at the rectifiers they used too.

All in all, easy and mostly cheap mods that will raise the sound quality of your amp.

[G]

Hey guys, finally got some tube gear coming my way ... a Chinese Integrated, Yaqin MC-10L like this

http://cgi.ebay.com/YAQIN-MC-10L-MC10L-Integrated-Tube-Amplifier_W0QQitemZ370097706772QQcmdZViewItem

Also got a schematic for it, so let the modding begin!  Just wondering what tubes to try in it first?  Would some Svetlana EL34's be a choice?

I recommend the EH EL34s. After trying several brands in my SE amp they are the ones I kept putting back in and enjoying.

[Rex Everything]

The SED's are they way to go in new production EL34 IMO.

[bunnyma357]

Sorry for the late response to an older thread, I just joined AC a couple of days ago.

I have an MC-10L as well, and what I found was that changing the pre-amp tubes made a much bigger difference than changing the EL-34's.

I went with some NOS Russian Military 6N1P-EV's from the Vokshod factory (Missle Logo). These are pretty cheap on eBay - about $2 each and made a pretty big difference. The 6N1P is similar to the 6DJ8/6922/7308, but not a direct replacement - they may or may not work well, but I haven't tried them. I did try using a 6N1P in place of a 6922 in another amp and it did not sound good.

For EL-34's - I went with the Groove Tubes EL-34M's (GT Rating 10 = late break-up distortion) which are supposed to be pretty decent copies of old Mullard's, not just a rebranded generic Russian tubes like most GT's. It made a little difference, but nowhere near the impact of the 6N1P's. Supposedly the Chinese EL-34's are actually a relatively decent tube. Like you I couldn't handle the cost of good NOS tubes and the Groove Tubes are recommended new production tubes on the Brent Jesse tube site.

Do you have one of the newer MC-10L's with the bias pots exposed or the older one with the 4 tall capacitors between the pre and power tubes?

Jim C