MC275 with Aeruis

Dear All
I have a pair of Aerius and I have changed the panels 6 months ago.
Reading this forum I decided to but a mac amp. I have found a 275 GG edition. The sound was what i liked, but after one month a OT got burned.
I went to the Mac dealer and trade it in for a new 275 V.
I have hooked up to Aerius for 1 week and everything seems ok. But I have noticed that the OT that stays in the mid between the other OT and the Power trans gets hotter than the other OT.
Is this normal?
Can Aerius burn OT of a mac?
BTW I had also a mac (pre owned 2200) and it get damaged too, always connected with Aerius.

Thanks a lot for the help
Ciao
Alberto

Are you getting clean well grounded power?

Any brown outs in your area?

Does this thread apply to your situation?
http://www.martinloganowners.com/forum/showthread.php?t=5693

Alberto, the Aerius is not the culprit. As almost every new Mac (tube) equipment owner (except for the most die-hard -- and lucky -- Mac-groupies) will tell you, the current OEM McIntosh tubes SUCK! The Russian-made Electro Harmonix KT88 power tubes are unreliable and can take out plate resistors when they fail. And the Chinese-made signal tubes (12AX7, 12AT7) sound terrible AND when they occaisionally fail, can take out the power tubes, etc, etc.

I don't have time right now to explain why that one plate is glowing, better you should put ALL your OEM tubes away (until) if you're ever forced to sell that beautiful equipment ;-)

Replacements? The original (British) GEC, Gold Lion, or Gold Monarch KT88's (same tube, same company) are the best but very expensive. The best current manufacture KT88's are the PentaLabs (Shuguang) KT88SC, about $145/matched quad, I recommend www.dougstubes.com or the "reissued" Russian-made Genalex Gold Lion, about $220/matched quad (the Pentas are just as good, maybe better, IMO)

There are really no currently made signal tubes IMO that can beat the old ones. You can always experiment, but if you replace all the 12AX and 12AT tubes (in the amp and preamp)with NOS Telefunkens, you'll be AMAZED at the sonic improvement. (In the old days, McIntosh in fact used Telefunken and British Gold Lions for their OEM tubes!!)

Since you're driving electrostats, make sure your speaker cables have very low capacitance for the cleanest sound -- in other words Cardas would be a bad choice ;-)

Alberto said:

Dear All
I have a pair of Aerius and I have changed the panels 6 months ago.
Reading this forum I decided to but a mac amp. I have found a 275 GG edition. The sound was what i liked, but after one month a OT got burned.
I went to the Mac dealer and trade it in for a new 275 V.
I have hooked up to Aerius for 1 week and everything seems ok. But I have noticed that the OT that stays in the mid between the other OT and the Power trans gets hotter than the other OT.
Is this normal?
Can Aerius burn OT of a mac?
BTW I had also a mac (pre owned 2200) and it get damaged too, always connected with Aerius.

Thanks a lot for the help
Ciao
Alberto

Click to expand...

Hola Alberto...did you check the bias? This is very important for tube amps. Usually, I bring 5mV down of the bias, and they run perfect for my ears...this might help to you...some might agreed of disagreed with this, but I have never blew an output tube since I do this...and I use my system everyday!...happy listening,
Roberto.

roberto said:

Hola Alberto...did you check the bias? This is very important for tube amps. Usually, I bring 5mV down of the bias, and they run perfect for my ears...this might help to you...some might agreed of disagreed with this, but I have never blew an output tube since I do this...and I use my system everyday!...happy listening,Roberto.

Click to expand...

Roberto, the MC275 has no bias adjustment. All McIntosh amplifiers are fixed bias. Further, in most amplifiers that do have bias adjustment, the bias is adjusted for pairs of tubes (in push pull circuits) so it is not possible to adjust just one tube by itself. The pairs of tubes should be matched to begin with anyway, or the more powerful tube will wear out faster.

Dear All
sorry but the problems lies in the output transformers and not in the tubes (unless they go short).
I mean:
I have an output transformer that is hotter than the other (the one between the power transformer and the other trans.) is it normal?

You seems quite sure that Aerius cannot be the culprit, am I right?
Ciao
Alberto

nsgarch said:

Roberto, the MC275 has no bias adjustment. All McIntosh amplifiers are fixed bias. Further, in most amplifiers that do have bias adjustment, the bias is adjusted for pairs of tubes (in push pull circuits) so it is not possible to adjust just one tube by itself. The pairs of tubes should be matched to begin with anyway, or the more powerful tube will wear out faster.

Click to expand...

Hola nsgarch, In the tube power amps that I have still with me, Conrad Johnson MV-55, Sonic Frontiers Power two, Audio Research VT-100 MKII, VTL 225s, each amp has a bias pot for each output tube, and yes, all of them are push-pull. The only that has an auto-bias is the Margules...as an example with Sonic Frontiers, each tube has a two color LED, green (when the bias is too low) no color (when you are in the right amount of bias) and red (too much bias). On Conrad Johnson, when the red led is on, you have too much bias, bringing it down at a point when goes off, just there, you have it right, following C-J instructions. On Audio Research you have a test point also for this adjustment, but you balance two as you said before... So, I thought McIntosh was the same, on the McIntosh Model MC2000 you can adjust the bias... Thanks for letting me know that I was wrong with McIntosh MC275. Happy listening,
Roberto.

roberto said:

Hola nsgarch, In the tube power amps that I have still with me, Conrad Johnson MV-55, Sonic Frontiers Power two, Audio Research VT-100 MKII, VTL 225s, each amp has a bias pot for each output tube, and yes, all of them are push-pull. The only that has an auto-bias is the Margules...as an example with Sonic Frontiers, each tube has a two color LED, green (when the bias is too low) no color (when you are in the right amount of bias) and red (too much bias). On Conrad Johnson, when the red led is on, you have too much bias, bringing it down at a point when goes off, just there, you have it right, following C-J instructions. On Audio Research you have a test point also for this adjustment, but you balance two as you said before... So, I thought McIntosh was the same, on the McIntosh Model MC2000 you can adjust the bias... Thanks for letting me know that I was wrong with McIntosh MC275. Happy listening, Roberto.

Click to expand...

Thay's very nice, but I did not really require a response -- my post was for information purposes only

Dear All sorry but the problems lies in the output transformers and not in the tubes (unless they go short).
I mean: I have an output transformer that is hotter than the other (the one between the power transformer and the other trans.) is it normal?

Click to expand...

Yes it is normal. The middle output xfmr gets hotter than the left output xfmr because it's in the middle The power xfmr on the right is always the hottest, If you live in a very hot climate like I do, you might want to provide some extre cooling (see pic)

You seems quite sure that Aerius cannot be the culprit, am I right? Ciao Alberto

Click to expand...

If the Aerius xovr (or perhaps a speaker cable?) had a short circuit the amplifier fuse would blow, that's all. So check all your connections carefully. If there is a short circuit in the Aerius xovr, then you would get no sound from the speaker at all

BTW I had also a mac (pre owned 2200) and it get damaged too, always connected with Aerius.

Click to expand...

The C2200 is a preamp. I don't understand how/why it was connected to the loudspeaker?

Dear NSGARCH
thanks a lot.

I did suspect that the fact that was hotter because it was in the middle (in effect the Power trans is the hottest), but since I have just blown off one amp, I am really scared to damage the new one

The Aerius plays wonderfully, then I will connect them back again.

I made a mistake with the amp. I had an integrated solid state 2202, and also this one stop working (it has done it twice, once when it was connected with the Aerius).

Thanks again
Ciao
Alberto

Alberto said:

Dear NSGARCH
thanks a lot. I made a mistake with the amp. I had an integrated solid state 2202, and also this one stop working (it has done it twice, once when it was connected with the Aerius).

Click to expand...

Alberto, I am not familiar with McIntosh SS equipment, so I cannot give you any useful advice about your 2202 . . . . .but I can definitely tell you it wasn't bad tubes !

Please; do a favor for me, for yourself, your amplifier, your speakers, and especially for the music!: Put some good tubes in the MC275, you won't be sorry, I promise :bowdown:

Yes, I will change the tubes.
In the previous amp i got the GEC Gold lion (???) and they were quite good.
I will follow your advise.
Any idea on the cable amp-speakers?
Thank you very much

Alberto