Preamp question

[murraycamp]

Just jumped in the McIntosh pool. It's nice and warm in here!

Looking at preamps and would appreciate some input and experiences. I'm looking at the following units (all approx. same price range):

C712
C31V
C27
C28

This will be running a MC752 power amp and GE Triton 7 speakers.

I realize the C27/C28 don't have remotes, but that aside are there significant sonic differences between these units in your experience?

Also, I've included a poll.

Thanks in advance for your help.

 

[Mike Gibson]

IMO the C-31 & C-712 will be quieter than the others. Plus they are newer models also. I'd go with the C-712 as it matches your amp better and is newer than the C-31. That said I've had a C-31 and it was a very good preamp. I sold it when I bought a C-39 because I wanted the all glass front..

 

[c_dk]

There are two versions of the C31, one has the original Toshiba IC volume control, the later one the motor driven control Mac used for later units like the c35, c37 etal.

C28s usually will need 6-7 hours of restoration time.....a true classic from Mac but needy at its 40+ year age.

C27 is a upgraded C26 (29 is the same for the 28) that will not need as much restore time as the earlier preamps but being 35 years old is certainly coming due.

The 712 is much newer 1/2 height design so was not a populat as the full height units.

The C31s have the non collectible issue of video nomenclature and 1/2 glass, 1/2 aluminum face......

We have found that a recapped C31, 35, 30 or 37 can be stunning high performance preamps, with the 5 band EQ and variable loudness that many other preamps do not have.

All but the 712 are outside of the window were a recap is not a worthwhile investment, the C28 usually needs a much more in depth restoration.

 

[murraycamp]

Thanks for the advice guys. Looking at some different models on Audio Classics. Another consideration is expense of maintenance over long term. Once restored, wouldn't C28 be less expensive? Mainly thinking about the complexity (chips) of later units. I'm out of my wheelhouse on this one, though.

 

[Mike Gibson]

I would simply avoid the C-28. If you search here you will see lots of threads covering the volume/off/on switch and it's lack of availability. If you don't mind having AV inputs you can get a C-39 as cheap as a rebuilt C-28 or cheaper and have a quieter preamp. I've had a C-26, C-31, C-39 and now a C-100. I'd stick with a C-38 or newer. Just my opinion though.

 

[MORTIS]

Among those preamps listed, I've owned only the C712. It's the newest of the bunch and still unlikely to need any restoration. I found it to be an excellent slimline preamp, and I suspect the only one on your list with a remote. Another bonus of the C712 is the bulbs are very easy for anyone to replace; far easier than many other Mc components.

 

[techguy0192]

I own an MC752 and have paired it with a C715. It is currently connected to a C15. Both are excellent performers. I prefer minimalist designs, so I have an affinity for the 1/2 height boxes. My philosophy is buy the newest Mac preamp your can afford unless you're trying to go period correct with older amps for example.

 

[twiiii]

C=712 and 715 were very popular for us as a dealer. There was a matching tuner and Quite a few slim power amps. MC 502 and 7100 come to mid but I think there were other also. I thin it was a MR510, a C-715 and a MC 7100 or MC 122 made quite system.

 

[murraycamp]

Thanks all. I am talking to Steve at AC about a restored C712. I think I will heed the advice to buy newer if possible. I'll keep everyone posted.

 

[Mike Gibson]

Be sure and let us know what you get. Also pictures are especially nice for functional illiterates like me.

 

[murraycamp]

Will do

 

[62caddy]

Of that lot I would probably go with the C31.

Better specs and reliability than the others (probably similar to C712) but has 5 band EQ (which the C712 does not have) plus C31 is remote controlled.

 

[techguy0192]

I've never understood the drive to have the Eq feature. I've always left it flat or disabled. On rare occasions, I have enabled the Loud button on my C15 and C712, but only for very low level listening. Not saying there's anything wrong with wanting an Eq....people are free to like what they like. I can say with confidence that the extra knobs certainly look cool.

 

[62caddy]

EQ is useful to tame the occasional errant recording and/or environmental purposes. I know I could never live without it in my main rig.

The 5 bands McIntosh used are well chosen and minimal for the flexibility they provide.

 

[techguy0192]

@62caddy I'm in the straight wire with gain camp.

 

[MORTIS]

@62caddy I'm in the straight wire with gain camp.

That everyone's ideal, but when a particular recording needs a little help, it's always handy to have that tone/EQ option.

 

[62caddy]

@62caddy I'm in the straight wire with gain camp.

That's entirely fine.

I simply find that the benefit of EQ far outweighs that of doing without - given the unpredictability (at least that I've encountered) of recorded material. Most of the time I run flat, but it's nice to have when it's needed.

 

[FauxHall]

I've been looking at preamps and the most critical specification to me is the signal-to-noise ratio (SNR).

For the Macs, up tp C-32, they spec at 90 dB for line level. From C-33 onwards, they jump to 100 dB or above.