Mac 275 questions........

I just got 2- 275's. Im waiting for the C-2300 to come in to hook them up. Where are the stock tubes made? I am curious about the tube failure? That is a bit disapointing. I am also interested in the new tube replacment.

Yes Chiroman, we will have to compare our finding when we get both amps up and running. My 1st map will be in this Saturday (Jan 5th). The second should be in a week or so latter. This will give me some time to evaluate the 1 versus 2 amps etc.
What are your amps driving?

RWD (Rick)

For now they will be driving Klipsch LaScalas, but I am getting a pair of Tyler Acoustic PD80s. My Preamp should be here tomm or wed. Sounds like you have some serious speakers? Got a website for em'? I would like to check them out.
Thanks,
Gene

If you go to and search the McIntosh forum on AudioKarma, you'll find lots of 275 info and owner experiences. McIntosh used to provide the finest tubes with their new equipment such as Telefunken and (English) Gold Lion/Genalex, etc. For one thing they were plentiful and not particularly expensive.

Today, companies that make tube equipment have to favor price and availability over quality -- so of course NOS is absolutely out on both counts. The KT88 power tubes Mac uses are Electro Harmonix made by the American-owned New Sensor Co. in Russia. They have bought the rights to many old brands like Mullard, TungSol, Genalex, Svetlana, and would like you to think they are re-issuing the genuine article(s) but they aren't (mainly because they don't know how to make them:-) BTW, you can still get real Svetlanas from the S.E.D. company in St. Petersburg, now sold under the Winged-C logo after their company name was sold out from under them!

The Mac signal tubes (12Axx twin triode-types) are Chinese, made for them probably by Shuguang. If you have a new Mac power amp with OEM tubes, my advice is to run it for 5 hours or so without any power tubes, so you can find out if the little signal tubes are going to hold up (I even do this with NOS/vintage tubes too) If a little tube dies, it dies (no problem, and certainly no problem in a preamp) but in a power amp, it could take out a power tube (again, not a problem if it's a cheapie power tube ;-) BUT, a shorted or runaway power tube can damage bias and plate resistors, and even power transformers, and that's where the repair hassles and expense begin -- and unfortunately, the fuse doesn't always pop fast enough (which is why I keep my finger on the trigger when I'm using tubes with reported reliability issues!

On the positive side, tube problems usually show up very soon (1 hour to 1 month) and once they're past that, you shouldn't have to worry (but I NEVER leave tube equipment on when I leave, not even a tuner!) Also, problems usually occur during turn-on/warm-up, so once things are stabilized they're OK - usually ;-)

The thing to remember is that tubes have been used reliably for the last 85 years, and often in critical locations (like ICBM's) so don't discount their quality. The problem is that tubes aren't tested and then burned-in the way they used to be -- certainly not by manufactures (they are by many online tube sellers such as Upscale Audio)

I'm using a quad of NOS Genalex KT88's ($800) and a quad of GEC/Genalex 12AT7's ($250) in my 275 and never a hiccup; plus they last twice as long as the reissued tubes.

Gene, just click on (system) by my name (RWD).

Rick