Tube Recommendations for C22

TSmith8605

Senile Member
Subscriber
Hi all,
The Telefunken tubes in my C22 are exhausted and I can no longer find good Telefunken tubes anywhere.

Does anyone have recommendations for replacements. To be clear, this is an original (1960s) C22 and I need 6 12AX7s.

Thanks
 
Have you looked for other Telefunken tubes that were branded for other makes (there's a lot of Fisher labeled 12ax7 Telefunkens out there)?
 
I have never had any dealings with him personally but Jim McShane is brought up often as a straight shooting source for good tube solutions......

I believe if you are going to use vintage tube equipment you need to be a tube hoarder, collecting up what you can when you can and then of coarse use readily available common tubes for everyday use.

Kind of like a vintage British sportscar......you better have a everyday backup for when it rains.
 
I have never had any dealings with him personally but Jim McShane is brought up often as a straight shooting source for good tube solutions......

I believe if you are going to use vintage tube equipment you need to be a tube hoarder, collecting up what you can when you can and then of coarse use readily available common tubes for everyday use.

Kind of like a vintage British sportscar......you better have a everyday backup for when it rains.

You're right, I should have hoarded a bunch of Telefunkens 10 years ago when I got the preamp as they seemed much more available then than now. And I will check with Jim McShane and Doug's Tubes.

But I was hoping to hear peoples' opinions on the best brand of 12AX7 for use in McIntosh stuff.

I have recently let my tubes go for a long time (10 years) in both my Mc 275 IV and C22 and in the last several months simultaneously became dissatisfied with the sound on both (in two different systems). Prior to that, I would replace tubes more frequently just because, so I never got to the point of noticeable sound degradation. So I kinda wanted to see how long the tubes would last and if the sound would eventually go bad. It did.

On re-tubing the 275, the improvement in sound was immediately noticeable and substantial meaning the old tubes had clearly gone bad. The biggest difference is that with the old tubes, I always felt the need to to turn it up and then the amp sounded significantly underpowered, dirty and could easily be overloaded. With the good tubes, the amp is back to sounding powerful and I no longer feel the need to turn it up to use that power.

But I do have a cheap tube tester that only tests for emissions and shorts and all 11 of the "bad" tubes from the 275 still measured perfectly on the tube tester and all like tubes measured the same (e.g. all 4 KT-88s measure the same, etc.).

Point is, these older tubes tested fine but were not fine and this makes tube hoarding more difficult such that I do not trust just getting tubes that "are good" or "work" say on eBay or some such.

Also, 10 years appears to be too long and so I apparently will need good tubes every 5 years or so.

So I need to find a vendor who has test equipment that measures more parameters than my tester who can pick good used or NOS tubes from bad before I pay for them. Or I would like to find a source of new tubes that provide good sound. Getting good 12AX7s seems to the main problem. I have not been too happy with the sound of the Chinese 12AX7s in my 275 or C220.

BTW, I wish I had a test bench as I am very curious about what was going on in the 275 with older used up tubes - what was the mechanism for the poor sound and seeming lack of power? I would have liked to measure the power output to see if it was to spec.

Thx
 
All tubes in my MX110 are original and at 50+ years of age, it still exceeds factory spec. Mc is designed that tubes are never run to their limits therefore do not need to test "maximum" to make (or exceed) performance spec. Different story for output tubes however, which can wear more heavily depending on use.

Chris - at the Mc Clinics, how often did 12AX7s need to be replaced? I can't recall Dave ever mentioning having to replace a single one in his book - not even an MC240 that had been left on for 12 years continuously which only needed new outputs (and a voltage doubler) to make spec.
 
Last edited:
The spring clinic of 1979, DOB threw away a lot of tubes. (Yea I should have saved the waste basket). It was the last one where he was still replacing marginal tubes from his cases of back stock that he brought on the road with him. The fall clinic was at our other store, I am sure I popped in but did not work that bench with him.

After 1980 tube replacement at clinics basically stopped.

You have to understand the Mac guys looked at tubes as a electrical commodity, like the engineers they truly were. I would not want to get into a discussion with Gordon, Sidney, David etal about tube rolling.......having Palma there to referee would not be enough!!!.....it was almost not enough when getting into an interconnect "discussion" with Gordon!

I am sure today's tube rolling aficionados would claim that the "special" characteristics of their favorite tubes would degrade long before they would not meet spec. I think I agree with them, I would just like to find out the way to quantify what they are hearing with measurements of the units performance characteristics.....lab time in school has a tendency to train you that way.
 
Five of the six Telefunken 12AX7's in my C22 are original, only one was replaced when it was restored two years ago and it was only replaced to closer match it's partner. They are not exactly hard to source but they can tend to be rather expensive.
 
Getting back to the OP - and FWIW - If I owned a C22 in which the condition of the tubes were in doubt, mismatched, etc, without question I would ensure the unit receives a full compliment of 6 strong testing OEM Telefunken 12AX7, whatever it takes to make it happen. It's one of the most regarded 12AX7s and it is what McIntosh used.

A couple hundred dollars either way isn't worth fretting over given the value of a C22, especially in light of the increased worth a set of OEM Teles would add to the unit's worth over a set of x, regardless of brand.

Again, I would not be overly concerned with tubes testing at the highest order since McIntosh equipment does not require them to run that way. It is one of the reasons that make McIntosh what it is: Engineering design that takes into account tube deterioration whereas lesser designs may require nothing less than perfect tip top tubes in order to make spec.

One man's opinion.
 
Last edited:
Good ones, there are many. GE, RCA Sylvania, etc .are easier to find and they sure worked well back then.
Many new production tubes are fine to use too.

Ron-C
 
Current production, the Shuguang 12AX7 is a very good sounding and performing tube. At least in a guitar amp. It is very hifi, and I bet it would be great in a C22!
 
Should be able to find 6 strong testing Telefunken tubes. Genuine NOS are hard to find. I purchased two NOS from a tube seller I know in Canada for my C2300 and they cost $200 for the pair.

For the C500T I've put 4 lightly used Telefunkens in the line stage and 4 new production Russian Gold Lions in the phono stages. There are lot's of 12AX7's out there. I took a quick look on eBay and found a lot of GE, RCA and Sylvania.

I've gone down the rabbit hole of tube rolling in another amp I have. I'll only replace the above tubes if they fail.
 
I didn't realize the telefunkens were so hard to find now ... I've got a box full of vintage teles, amperex, sylvanias, rcas, etc. They were easier to come by when I was into tube gear I guess.
 
Hi all,
I may have found a source for Teles however, I think something else is wrong here and swapping tubes around is not helping. Symptoms include:
1. Microphonic noise in the right channel phono section (this was fixed by replacing tube V2, so at least one of the Teles has definately gone bad).
2. Not fun to listen to as it used to be (I thought this was worn tubes but . . .).
3. A popping fizzle static in the left channel (phono section) for a couple of seconds at start up / warm up (right channel remains silent). Swapping phono tubes and DeOxing tube pins and sockets had no effect on this.
4. Popping (mostly in the left channel) when switching the source selector amount phono / tape head inputs or from a line level to phono input - maybe some DC there that should not be.
5. Too much rubble / low freq surface noise from the Dual 1219 (not the strong suite of this TT but the noise is more prevalent than it usta be).
6. Bass is overwhelming loud, mushy and sometimes growly. I have to turn the bass control down 3 steps to get close to normal level (I think only in the left channel). BTW, I think this is the case with line level sources too (while items 3 - 5 point only to the left-channel phono section).

I just removed the C22 from the "vintage" system and installed the C220 (which BTW also has Teles) and all the symptoms are completely gone, so the issues above are in the C22. It took about 20 seconds of listening to tell the difference. When the system slowly degrades over a ten year period, it may take awhile to realize at some point that something is amiss.

So I will clean / DeOx the controls, but I suspect a leaky cap somewhere in the signal path (left channel phono section most likely). I have the service manual for the C22 but it does not show any test points with expected DC voltages so I will take a look. If I can figure out where I am in the circuit, I can compare DC voltages between the left and right channels. But I may have to send this off to L&M (in Daly City), Audio Classics or Terry D for work.

BTW, this is a second time a Tele has gone microphonic in the phono section and maybe the tubes are being damaged by the suspected leaky capacitor and resulting mis-bias somewhere.

Once it is working, I will reevaluate the tube issue.

Thanks for all the advice on tubes, BTW.

Edit: I was wrong, the schematic I have does show test points (tube pins) indicating the DC voltages that should be seen.
 
Last edited:
I cleaned things up and poked around with the voltmeter (easier than I thought) and all the DC voltages around the tubes and the main signal-path caps all look about right and consistent left / right to within 5%.

No smoking gun, so. . .

I dunno. I cleaned all the controls and connectors but have not hooked back into the system yet.
 
After cleaning all the controls, connectors and tube pins / sockets, I hooked up the pre amp and - everything is fixed! I am completely amazed at how much better it sounds. The bass is back in proper level, clean and tight. I put the original Telefunken tubes back in (replaced the microphonic one with another good Tele I have), and all is well. The sound is back to being amazing.

I don't need new tubes.

Since there was not much dust in the preamp (or my listening room), I suspect the problem was oxidation and not dirt on the contacts.

So, while I was amazed at the amount of improvement, I can understand why oxidation might make the sound crapy and mushy but why would oxidized contacts cause the bass to be way too loud? I don't know, but I have a theory that I cannot prove or test now since I cleaned everything at once.

This preamp has two little knobs on top (one per channel) for something called bass trim. The owner's manual says: "Low Frequency Trim Controls (L and R): Allows frequencies below 100 cps to be boosted up to 6 db to compensate for unequal speaker response." I had these knobs all the way down for no bass boost, but I'm thinking if these trim pots (which I did clean yesterday) were dirty and not making internal contact correctly would add a bunch of resistances and be essentially the same as turning the knob to the full boost position - except the resistance comes from the oxidation and not the variable resistor element.

This project is done except since the preamp is the center of all things, my equipment rack is all torn up with wires going everywhere so I'll have to put all that back - PITA.

Also, I guess every 5 years or so, I need to take the preamp apart and clean everything. I guess it's time to also clean the other older Mc stuff around the house. Things are not as sealed up in this 1960 design as compared to modern stuff.

Anyway, thanks for reading my little saga here.
 
Glad to hear it.

Original Telefunken 12AX7 are the gold standard as far as I'm concerned, which can last a lifetime when used in McIntosh.
 
Glad you found a cheap fix, my MX110 began to sound lousy one day and sure enough it was the mode switch, I took it apart and cleaned all switches and pots. I also occasionally exercise all the pots and switches of my gear even when not in use. I once had a stubborn tele 12AX7 tube in my Scott receiver that just wouldn’t mate well in its socket no matter what I did. I traded with a tube in another position and all was well.
 
Back
Top Bottom