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!


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.