Tubes Recommendation for McIntosh Preamp

Hi,  I recently purchased an used McIntosh 2-chassis C1100 tube preamp.   So far I'm pretty happy with it.    

I'm thinking about replacing the line level stock tubes.  They are 2 12AT7 and 1 12AX7A per channel.   

I'm looking for recommendation from fellow members here.   I would like something on the warm side (definitely not bright sounding), and good solid and tight bass.   

Also I wonder if I need matching.  e.g. do I need 2 matched pairs of 12AT7, with each matched pairs for each channel.  Or do I need matched quad of 12AT7 for both channels.   Same question for the 12X7A.  Do I need them to be matched.   I don't seem to see any information available in the user manual on tube replacement.

Thanks very much in advance!


I have a C2700 with similar tube complement, 2 for line stage, 2 for MC, 2 for MM, I replaced them with NOS tubes and its much much better then the stock JJ tubes mac uses (way to bright, toneless). 

matching is cheep, why would you not get them matched.  

 tube depot, tube store have tube kits for these preamps you may want to check that out first as a starting point. New production tubes in the kits but NOS tubes are all over the internet some good some bad. google is your friend. 

Hi @glennewdick, may I ask you which NOS brand did you get?

Most comments I read from the internet is that NOS tubes are better than new production. I don’t mind buying NOS. In fact, I got some NOS for my other preamp (Cary SLP-05) and quite like them. But I'm also curious about how much longer can the inventory of NOS tubes last. I would think they eventually run out,


How do you know that these tubes a seller claims are NOS aren't just pulls/used? For example a lot of Tektronics scopes used Telefunken 6922/6DJ8's. When those scopes were scrapped those tubes appeared on the market, fraudulently being sold in factory boxes as NOS at premium prices.

Hey @immatthewj, I still have the Cary SLP-05. I guess I’m keeping it as a spare for now.

The purchase of this McIntosh is kind of a coincidence. I ran into the C1100 for sale ad while I was browsing around in Audiogon one day. From the pictures, it looked very clean and the price was reasonable. So I contacted the seller, who happens to be an audio store. They got the C1100 as a trade in from a customer, and I was told it was only a little over a year old. Of course I can’t verify that. I just have to take his words.

So I decided to take a chance and purchased it. Given the pretty good resale value of McIntosh, I figure I can probably sell it for around the same price if I’m not happy with it.

When I got the delivery, I was very happy to see how clean it looked. It was in mint condition, almost like new. When I plugged it in and started listening to it, I wasn’t happy with the sound. It sounded thin and bright. So I contacted the dealer to see if he would take it back, and I even offered to pay him a restocking fee. He told me to give it some time. He said the unit hasn’t been played for a while, and it will require some break in time again. I’ve never heard of that before, have you? but I decided to take his words for it. As it turned out, he was right. After I gave it a couple of weeks of playing, it started to open up. The brightness was gone, and sounded more smooth, rich, and warm. I was quite happy with the sound.

Since then, I haven’t switched back to my Cary to compare the sound. It’s been about 6 months now. From my memory, the sound of the Cary is on par with the McIntosh. So I won’t say the Mac is better or vice vera. If I ever get around to plug in my Cary again, I’ll let you know how it compares to the McIntosh.



I was told it was only a little over a year old. Of course I can’t verify that. I just have to take his words.

if this is important to you (and I am not saying that it is) you could probably call or email the people at Mac and if you gave them the serial number they could probably give you date of manufacture and possibly other odds and ends.

He said the unit hasn’t been played for a while, and it will require some break in time again.

If it had been recently retubed, perhaps?  I've also read posts abour capacitors needing some running time for them to "reform."  I cannot personally attest to that, it is just what I have read about on this site.





Good suggestion @immatthewj on contacting McIntosh.  I thought about that too.  In fact, the dealer that sold me the Mac told me that the previous owner had sent in his warranty registration card, so therefore, the warranty is transferrable.   Again, I took his words for it.   I was going to contact McIntosh to verify that.  Maybe one day when I have some spare time.

Sorry for side tracking,  😀.   Will still welcome any tubes recommendation for the McIntosh!




I previously owned a Mc C1100 and replaced stock tubes with Telefunken 12AX7 and 12AT7. Telefunken is much better than stock tubes. Once you hear them, you don't want to revert back to stock tubes. 

FWIW, I replaced the stock 12AX7 tubes in my C220 preamp with Mullard reissues.  I got a lower noise floor, smoother highs without losing detail, and slightly expanded soundstage.  A great low cost upgrade.

Also, FWIW, on a C2500 I swapped in NOS Telefunken 12AX7.   Huge  improvement across the spectrum.    

For what it's worth, I own the McIntosh MA352 Integrated Amplifier which uses 2X 12AX7A tubes and 2X 12AT7 tubes.  I believe McIntosh sources from New Sensor but I don't have direct confirmation from the company.  I've been using the stock tubes for five years now without any issues.  The sound is great and I have no complaints.  Recently, I replaced the 12AX7A stock tubes with a matched pair of low micro-phonic 1960s Amperex Bugle Boy tubes for comparison.  I bought these tubes about a decade ago.  I stored them when I sold my tube equipment.  Having heard the stock McIntosh tubes versus the NOS Bugle Boys, the McIntosh tubes sounded better to me.  The stock tubes are more crisp (clarity & imaging), quieter (sound stage), and the bass was significantly tighter.  Additionally, the NOS tubes cost $130 a piece while current issue New Sensor (Russia) cost less.  Needless to say I put the stock 12AX7A tubes back into the equipment.  I do know that McIntosh individually tests their equipment with the stock tubes prior to delivery to ensure the best sound and compatibility.  Save yourself some money; instead of buying NOS tubes, it might be useful to consider premium New Sensor tubes as an alternative.  Cheers!

Thanks very much @wescoman for sharing your experience, Very helpful.

I actually think the current sound is not bad with the stock tubes. I was told the unit was about 1 year old, but I don’t know how many hours did the previous owner put in on the unit,

I have no experience of what a bad tube sounds like. So I thought for my own peace of mind, I would try some new tubes. But it is so good to know that you are running the stock tubes for 5 yeas without any problem. That’s wonderful!

I might just leave it for a while and see how it goes!




I sort of remember a thread up not all that long ago by someone bitching about the quality of the stock JJ (I think they were 12 ax7s) tubes in his Mac (I cannot remember if it was an amp or a pre).  That was making me think that Mac was putting JJ small signal tubes in from the factory.  Anyway, fwiw, not too long ago I put some JJ 6SN7s in my pre, and I don't think they sound all that bad.

Yes, most comments I read here in this forum mentioned that McIntosh uses JJ tubes in their tube components.  I actually have never heard of New Sensor mentioned by @wescoman.  

Nevertheless,  I guess McIntosh does a good job picking the right tubes for their product.  At least I hope so anyway.  😀.  Unlike Cary Audio SLP-05, I think most comments I read are negative with their stock tube made by EH.

I'm using some RCA 12ax and 7AT's not the most expensive tubes in the NOS market (I payed $25 each)but they have similar detail to the JJ stock tubes and have much better sound staging and bass control, not overly rich like some of the other NOS tube like the apprex and mullards. I have a really handy chart with sound characteristics of the 12 series tubes I'll see if I can figure out how to post it here its saved as a picture. 

I sent you a message with my email address i’ll email it to you i can’t figure out how to post it here. Ive also put it in my system pictures for anyone else. good for all 12 series small signal tubes like the 12ax7, 12at7, 12au7, etc. chart says 12au7 but they are all similar enough the charts good for all 12 series. 

Yeah. I did see your message, but when I went to click on it. It removed all the emails information. I don’t think they allow exchanging emails because they don’t want people doing business behind their back,

Actually I just clicked on your system, and I see the positing of the 12AU7 tubes.  Very nice thanks!

I also like your system, especially that cool Sansui tuner.  👍

This guy is very knowledgeable on MAC gear and what tubes work best with their various amps.