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McIntosh C2200 and C2300 Nudies

J

jdandy

Super Member
Banned
I received some new 12AX7 tubes yeaterday, both NOS Telefunken, and new Tung-Sol. I was swapping both brands of tubes in and out of the C2300 in my main system, and the C2200 in the studio system, comparing them with each other, as well as with the McIntosh issue 12AX7 tubes manufactured in China. It was fun, and enlightning. No surprise, the Telefunken tubes are golden, but surprisingly, the new Tung-Sol tubes, manufactured by New Sensor in Saratov, Russia, sound very good, and at a price that you can live with.

While I had both preamps open, I took a couple photos of each. I'm posting them here for anyone who might be interested to see interior shots of the C2200 and the C2300. Photos one and two are the C2200, and photos three and four are the C2300 for those who don't recognize the gear.
 

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Dan,

Thanks for posting the photos.

I am getting ready to order some Tele's to go in my 2200 and I am more than a little intimidated by taking the cover off and replacing these tubes.

Your photos help.. thanks.
 
two dot said:
Dan,

Thanks for posting the photos.

I am getting ready to order some Tele's to go in my 2200 and I am more than a little intimidated by taking the cover off and replacing these tubes.

Your photos help.. thanks.
Click to expand...

I've done that, too. The back 4 tubes under that cute little 'top hat' are the phono tubes and the front 4 are the line stage tubes, if that helps any, Dan.

FWIW, I've installed Teles in the 12AX7 positions but didn't hear much differece, frankly. I ended up with some of the Sovtek 12AX7LPS in those positions to help keep the noise down to a minimum. Using RFT 12AT7s for the other positions and haven't felt the need to make any further changes.

Cheers,

David
 
two dot said:
Dan,

Thanks for posting the photos.

I am getting ready to order some Tele's to go in my 2200 and I am more than a little intimidated by taking the cover off and replacing these tubes.

Your photos help.. thanks.
Click to expand...

two dot.......No worries, mate. Turn off the power switch, and unplug the power cord from the back of the C2200 while your are working inside. Remove the two screws on each side of the cover, and two on the top edge on the back of the cover. Slightly pull out at the lower bottom, side edges of the cover on each side, and pull the cover rearward. It usually lifts right off. You may have to raise the cover an inch or so at the rear, then pull backwards, since McIntosh uses some tacky stuff along the front edge to keep the cover from vibrating. It will release as you pull the cover back. You might have to wiggle the cover slightly side to side to get this adhesive to let go. Take it easy, and keep pulling it rearward. Once you have done this, it will come off easier the next time.

Your line stage tubes are the four closest to the front of the preamp (two 12AT7 and two 12AX7). The 12AX7 tubes are the gain tubes, and the 12AT7 tubes are acting as buffers (low or no gain) as I understand it. You'll also have to remove the one screw that holds the tube top support in place, and lift it off. Pay attention to the tube markings on the circuit board. The are printed on the circuit board at the base of each tube socket. The tubes in the phono gain section (back four tubes) are reversed from the front ones, that is the 12AX7 tubes are the back most tubes. Pay attention to that.

Take your time, don't get in a hurry. It is simple. Don't forget to reinstall the tube top support, then reinstall the cover, and the cover screws. Reenergize, sit back and enjoy.
 
Dan...thanks for the nudies...:yes:

btw.....doesn't opening the top cover void the warranty? I hope no warranty people are reading this post...:D
 
Nice work Dan...I was thinking of changing out the tubes in the MC phono section of my C2300 with NOS Telefunkens as well and wondered if it makes any difference. Well, I changed out the 12AX7's in my MC275 and holographic comes to mind, I will agree with you on the reissue Tung-Sols; they are worth their weight in gold for the price. The tweaks never stop:no: It seems like every week I am doing something, got it just right...hmmmm...let's tube roll...just right...hmmmm...change the interconnects...just right...change the speaker cables, cartridge, isolation....and the list goes on! It never ends and I love it:yes:
 
'cisco.......I wouldn't think so. Tube maintenance is normal. Honestly, I'm not concerned about it.
 
Interesting to see how different the circuit board and general layout inside each is.

No wonder they sound different.
 
Dan,

Thanks for the thoughtful and kind response.

That will be very helpful, once my tubes arrive.

Just a little intimidating the first time thats all...


Thanks,

Stephen
 
jdandy said:
I received some new 12AX7 tubes yeaterday, both NOS Telefunken, and new Tung-Sol. I was swapping both brands of tubes in and out of the C2300 in my main system, and the C2200 in the studio system, comparing them with each other, as well as with the McIntosh issue 12AX7 tubes manufactured in China. It was fun, and enlightning. No surprise, the Telefunken tubes are golden, but surprisingly, the new Tung-Sol tubes, manufactured by New Sensor in Saratov, Russia, sound very good, and at a price that you can live with.
Click to expand...

Thanks for the very useful report and great pics!

Which of the TungSol did you use? I see two models on TubeDepot, a ~$15 and a ~$30. The $30, gold-pin, is supposed to be lower noise. See link below for the TubeDepot page.

http://www.tubedepot.com/12ax7.html

Thanks,

Alberto
 
misterdoggy1 said:
I noticed 8 tubes in the C2200 and only see 6 in the C2300 ?

How come ?
Click to expand...

The number of tubes in the C2200 is eight. The circuit design is such the two 12AX7 and two 12AT7 tubes are used for the line stage gain, and two 12AX7 and two 12AT7 tubes are used for the moving magnet phono gain stage. As I understand the circuits, the gain tubes are the 12AX7's, while the 12AT7 tubes are used as a buffer (I think for low impedance matching).

The number of tubes in the C2300 design is six, such that two 12AX7 tubes are used for line stage gain, two 12AX7 tubes are used for moving magnet phono gain stage, and two 12AX7 tubes are used as the second amplifier gain stage after five pairs of low noise transistors for the moving coil phono gain stage. I'm not positive, but I think both phono stages are buffered for low impedance by unity gain operational amplifiers.

The C2300 also uses the McIntosh R-Core transformer, which generates less stray magnetic fields and suppresses mechanical noise.

What is really interesting about the C2300 line stage gain is the discrete component 12AX7 tube amplifiers are capable of 16 volts RMS at the balance outputs. That is three times the voltage required to drive McIntosh power amplifiers. This equates to indredible dynamic range, and ultra low distortion.

Hope this clears up the tube count question.
 
Alberto......I chose the standard Tung-Sol 12AX7 tubes, primarily because I did not plan to use them in the phono stages. It is only in the phono stages that noise tends to be an issue with almost any tubes. The Tung-Sol 12AX7 gold pin tubes are rated quieter, and as such, would be expected to be very quiet in the phono stage. I did test the standard Tung-Sol 12AX7 tubes in the moving magnet phono stage on the C2300 yesterday. The results were superior to the stock McIntosh issued tubes, and I did not notice an increase in the noise floor. I did notice a more open, airy sound, with very tight dynamics, and a solid bottom end. In the end, the Telefunken 12AX7 tubes were the tubes of choice for both the line and phono stages. The Telefunken tubes are magical, organic, tight, airy, three dimensional, and so smooth from top to bottom, without a hint of grain or glare.

I'll keep the Tung-Sol tubes as first choice back ups. The factory issued McIntosh tubes are all the way in the back of the cabinet, not likely to ever be used again.
 
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