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C11 VS C22 - Taking The Gloves Off

C

CountD

Super Member
ANYONE have a C11 and C22 and put these things side-by-side? I really want to know what the deal is. I want to buy a C11 this month just to do it. I always wanted to do it. Anyone who has done it?

One of the few pres I haven't owned, I really want to get to the bottom of this because it's bothering me. I have heard rumors that it is close to a C22. I want to put this rumor to rest.

I think I am selling my MX 110 Z and buy one on the bay just to do it.

Just wanted to get this out there and see what you guys think. I think the C11 may be a sleeper and game changer. I don't think I am going the C2200 route now.

The Mx110 Z has lost it's luster for me. Sounds too lean and too thin.
 
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I had a c11 and it was either all or nothing if you left the loudness button to the off position it was weak sounding if you pushed it to on it was over powering and hard to listen too..
 
Someone here 5 or 6 months ago posted his restoration of a C11. I believe a c22 is mostly a c11, but with different cosmetics.
 
strat10 said:
I had a c11 and it was either all or nothing if you left the loudness button to the off position it was weak sounding if you pushed it to on it was over powering and hard to listen too..
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Ditto with the MX 110 here.

If it only had V loudness, it would be perfect.
 
I recently rebuilt/restored a C11. The thread with pics is here: http://www.audiokarma.org/forums/showthread.php?t=583360

EDIT: Here is the link to the C22 rebuilt by NOSValves: http://www.nosvalves.com/C22.htm

A side-by-side comparison of the schematics shows that they are the same preamp. On the last page of the C22 Service Manual, there are some schematic notes detailing a few minor differences among early and late units; the C11 can be classified as an "early version" C22 based on analysis of the schematics. The minor differences amount to a particular capacitor value in the phono stage, some resistors added on the high-level inputs, and additional tape I/O jacks routed to the front panel. The volume trimmer pots are different, necessitating two additional resistors and the electronic circuit modules (RIAA and tone controls) were sourced from Erie on the C11 and early C22, later ones used Sprague parts. Lastly, there is an additional capacitor associated with each V4 and V5.

C11 schematic: http://akdatabase.org/AKview/displayimage.php?album=7&pos=16

C22 schematic: http://akdatabase.org/AKview/displayimage.php?album=7&pos=32

A solder-savvy user could easily incorporate the few minor component changes in a C11 to replicate a C22. I don't know if it would make any difference in the sound, however.
 
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62caddy said:
According to Charlie Randall, MX110 preamp is also equivalent of C22.
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Comparing the schematics, I don't buy it. In the preamp section of the MX-110, I see a different topography, different tubes, different component values. I just don't see the similarities. The C11 and C22 are identical twins in side-by-side comparison.
 
I read where the only difference between a C11 and a C22 are their cases inside they are mostly Identical the C11 is the poor-man's C22.
 
DC said:
I recently rebuilt/restored a C11. The thread with pics is here: http://www.audiokarma.org/forums/showthread.php?t=583360

EDIT: Here is the link to the C22 rebuilt by NOSValves: http://www.nosvalves.com/C22.htm

A side-by-side comparison of the schematics shows that they are the same preamp. On the last page of the C22 Service Manual, there are some schematic notes detailing a few minor differences among early and late units; the C11 can be classified as an "early version" C22 based on analysis of the schematics. The minor differences amount to a particular capacitor value in the phono stage, some resistors added on the high-level inputs, and additional tape I/O jacks routed to the front panel. The volume trimmer pots are different, necessitating two additional resistors and the electronic circuit modules (RIAA and tone controls) were sourced from Erie on the C11 and early C22, later ones used Sprague parts. Lastly, there is an additional capacitor associated with each V4 and V5.

C11 schematic: http://akdatabase.org/AKview/displayimage.php?album=7&pos=16

C22 schematic: http://akdatabase.org/AKview/displayimage.php?album=7&pos=32

A solder-savvy user could easily incorporate the few minor component changes in a C11 to replicate a C22. I don't know if it would make any difference in the sound, however.
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Thank you for this great explanation. Seems like the C11 is a dark horse compared to the C22 by far. And they sometimes get 1/3 of the price. And on top of it, a C11 (by production numbers) is very rare, but they do come up.

NOTE: The preamp section of the Mx110 is not even close to the C22. The final stage uses 6U8s - not close to the 12AX7s. By looking at the schematic very quickly, they look nothing alike.
 
DC I just checked your post on the C11. Awesome work. It has inspired me to get one. I won't be going the full route you did. If the old caps check out I keep them in there. Same as with my C22. I like the sound, and if they're not leaky I don't do it. Especially when it sounds good. I will keep you guys in the loop when I get one and have a side-by-side test.
 
I had a used C-11 that I sold so I could purchase a new C-22 back in the middle 60's. A friend of mine still has a C-11. They are pretty much the same unit internally as I remember, but at the time I thought the C-22 was cleaner sounding and was a big step up in looks, chassis, and assembly technics. But if totally restored with quieter resistors and caps in the phono circuit, I imagine sonically they would be very close. Not knowing how to set levels when combining the pre-amp with a power amp can really screw up the listening experience. Remember your amp has to have a minimum impedance of 150,000 ohms for the input. And the sensitivity should be between 2.5 and 3 volts for proper mating between the two. Any higher sensitivity and noise will enter the system and the loudness function won't track properly. Keep the cables between the amp and preamp very short to prevent anomalies in response and rise in distortion. I always used the twin amp inputs on 275's and 240's with the pots set about 10:00 to 11:00 o'clock for efficient speakers from Klipsch, EV, and Altec and at 12:00 o'clock on the power amp for Bozaks and less efficent speakers from Ar and KLH etc during that time. Using the old pre-amps with the new Mac amps with medium low input impedance is a definite no, no. That's why the current tube pre-amps are hybrids using SS buffers thought out the units to improve performance and allow them to drive low impedance inputs on SS state power amps. Low impedance connecting circuits are quieter and are less susceptible to external influences.
 
strat10 said:
I had a c11 and it was either all or nothing if you left the loudness button to the off position it was weak sounding if you pushed it to on it was over powering and hard to listen too..
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I guess that depends on a few factors. The condition of the preamp, the amp it's paired with and the speakers. My C11 has a very robust low end without the loudness button pressed. In fact, sometimes I have to pull back on the bass a bit so as not to disturb the neighbors in my building. It's a beautiful looking and sounding preamp it just does't have the sex appeal of the C22, but they are basically the same preamp.
 
So I have a C11 and concur w johnnytheg..

I never use the loudness switch, even with Spendor SP1 speakers which only have a ported 8in woofer and aren't known for dipping very low in bass response. However the most critical area has been speaker and power amp pairing IMHO.

Bottom line and I think Terry Dewick would agree it's a C22 for a much better value and to some of us better looking too....

I wouldn't trade mine except for maybe a really really nice vintage Audio Research or Vintage Marantz.

Jeff
 
Marantz model 7 and 7C aren't as neutral as a C-11 or 22. They are more forward sounding has been mine and others experiences. Especially if you are using Horn loaded speakers, like Altec, JBL, Ev and Klipsch. For speakers that need a little cleaning up like some KLH and AR models or other New England sounding speakers Marantz pre-amps might be to your liking. I much preferred the feel of the controls on a Model 7C. I will say at this point I will never go back to tubes, even though I liked the sound of the C500T. But I can do so much more with my C-34V and my first C-28 was a big step up from a C-22 sonically, though it was a pain to keep operating. Loved my C-29 and liked the sound of C-30 and 33 pre-amps I installed. If I had the space I would have. C-40. I guess if some one gave me a new current C-22 I would smile and not throw it in the trash.
 
twiiii said:
some one gave me a new current C-22 I would smile and not throw it in the trash.
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I have one, and it's damn good. Running an MC240 and a pair of MC30. Still have the stock tubes in it, but planning on rolling those out if someone wants to make some recommendations.....
 
I had to replace the tubes every year or more often to keep my original C-22 being the best it could be and Telefunken tubes were rather cheap back in the 60's. Of course Davie Obrien came every other year and installed a new set, too. So if you have original tubes you are tying your sound systems hands behind its back restricting its ultimate performance.
 
Ok so the C11 and C22 are essentially the same preamp. I note that the C8 is also 12ax7 based. How close is the C8 circuit to the C11/22 ? Of course the comparison is for one channel..... Thank you.
 
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