McIntosh MHA200 Impressions
Dec 19, 2021 at 2:30 PM Post #631 of 890

funkur

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McIntosh almost never disputes a tube issue during the 90 day tube warranty
I was a little surprised too, but the dealer's staff are old friends and hook me up all the time, so I didn't want to press the issue.
 
Dec 19, 2021 at 3:10 PM Post #632 of 890
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I was a little surprised too, but the dealer's staff are old friends and hook me up all the time, so I didn't want to press the issue.

It is very odd. In 18 years of being a McDealer I’ve never had this happen. It does seem your dealer offered a good option for you though.
 
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Dec 19, 2021 at 10:30 PM Post #633 of 890

vo_obgyn

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Who can spot the anomaly on this picture?

red_plate_v4.jpg

In the wake of an earlier post on this thread the unit went to McIntosh repair immediately through my favourite hi-fi shop. Thanks to them I was still able to enjoy an MHA200 in a form of a temporary replacement unit during the waiting. Now it is back, all good, one tube had to be replaced.

First newbe question: One tube? Are they not supposed to be matching pairs?

Second thoughts: I am completely new to tube amps. If this is a common issue with possible heavy consequesces, should it not be described in the manual with some illustrations? Are there safety circuits in the MHA200 that could avoid the heavy consequences in case the red plate tube goes off when it is not recognised in advance? (Sorry for the dusty picture, the mash was removed first time after two months of ownership)

red_plate_v4_only.jpg
Is the anomaly the reddish area on the tube? What is it called when this happens to a tube?
 
Dec 19, 2021 at 11:15 PM Post #634 of 890

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Is the anomaly the reddish area on the tube? What is it called when this happens to a tube?
Yes, that is. It is called red plating.
The protective mesh above the tubes also became quite hot, it was uncomfortable to touch, where it is normally just pleasantly warm.
Maybe that is how I have noticed it.

Some fun measurements after removing the mesh:
This is the normal tube. The red dot on the tube is the laser pointer of the temperature scanner.
normal_tube.jpg


This is the plate of the red plated tube

redplate.jpg


This is when I managed to hit the heating wire around the top of the plate with the scanner:
heating-wire.jpg
 
Dec 19, 2021 at 11:30 PM Post #635 of 890

vo_obgyn

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Yes, that is. It is called red plating.
The protective mesh above the tubes also became quite hot, it was uncomfortable to touch, where it is normally just pleasantly warm.
Maybe that is how I have noticed it.

Some fun measurements after removing the mesh:
This is the normal tube. The red dot on the tube is the laser pointer of the temperature scanner.


This is the plate of the red plated tube



This is when I managed to hit the heating wire around the top of the plate with the scanner:
Interesting, thanks for the illustrations and explanation. I had the Ray Samuels Emmeline II “The Raptor” tubed headphone amp and now the McIntosh MHA-200 and have not seen this anomaly yet. Not glad that your tube red plated but good for me to see what it looks like.
 
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Dec 20, 2021 at 9:58 AM Post #636 of 890

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Suggested Rule #1 for MHA200 owners…

‘Don’t talk about Red Plating.”

Posted about mine yesterday and today my third McIntosh12BH7A bites the dust.
Enjoying a little solid state by way of Chord Anni as the McIntosh cools down for some new tubes.

red plating 3rd setUntitled.jpeg
 
Dec 20, 2021 at 11:39 AM Post #637 of 890

vo_obgyn

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Probably because McIntosh is their biggest client so they price match to keep McIntosh happy. The 12BH7a doesn’t really affect the sound so that tube value from nearly any supplier is very likely going to keep the MHA200 sound signature in tact.
I’m finding the JJ 12BH7A tubes at several places for about $20.
 
Dec 20, 2021 at 4:20 PM Post #639 of 890

funkur

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Suggested Rule #1 for MHA200 owners…

‘Don’t talk about Red Plating.”

Posted about mine yesterday and today my third McIntosh12BH7A bites the dust.
Enjoying a little solid state by way of Chord Anni as the McIntosh cools down for some new tubes.

red plating 3rd setUntitled.jpeg

Damn. Can’t trust those basic Mc/JJ tubes.
 
Dec 20, 2021 at 6:38 PM Post #640 of 890

Newsee

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Suggested Rule #1 for MHA200 owners…

‘Don’t talk about Red Plating.”

Posted about mine yesterday and today my third McIntosh12BH7A bites the dust.
Enjoying a little solid state by way of Chord Anni as the McIntosh cools down for some new tubes.

red plating 3rd setUntitled.jpeg
Did not you say you went for Electro-Harmonix 12BH7 Gold tubes?
 
Dec 20, 2021 at 7:31 PM Post #641 of 890

u2u2

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Did not you say you went for Electro-Harmonix 12BH7 Gold tubes?
Yes and I used a set while I waited for McIntosh to follow through on my warranty… That took many weeks… They sent me a full replacement set of 4 tubes, drivers gave up first (noisey), and today the power tube red plating. Rolled in an unused pair of EH 12BH7 this afternoon and they work beautifully. I now have 2 sets of good EH power tubes and a couple of sets of Mullards (4024 & 6201) for drivers. No more McIntosh tubes for this amp. Been more tube changes in this amp than I care to count. I bought it with the illusion I wouldn’t tube roll as I have my Woo amps for that. Could not have been more wrong.
 
Dec 20, 2021 at 7:40 PM Post #642 of 890

Slim1970

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Yes and I used a set while I waited for McIntosh to follow through on my warranty… That took many weeks… They sent me a full replacement set of 4 tubes, drivers gave up first (noisey), and today the power tube red plating. Rolled in an unused pair of EH 12BH7 this afternoon and they work beautifully. I now have 2 sets of good EH power tubes and a couple of sets of Mullards (4024 & 6201) for drivers. No more McIntosh tubes for this amp. Been more tube changes in this amp than I care to count. I bought it with the illusion I wouldn’t tube roll as I have my Woo amps for that. Could not have been more wrong.
How do the 6201's sound in the MHA200?
 
Dec 20, 2021 at 7:59 PM Post #643 of 890

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Yes and I used a set while I waited for McIntosh to follow through on my warranty… That took many weeks… They sent me a full replacement set of 4 tubes, drivers gave up first (noisey), and today the power tube red plating. Rolled in an unused pair of EH 12BH7 this afternoon and they work beautifully. I now have 2 sets of good EH power tubes and a couple of sets of Mullards (4024 & 6201) for drivers. No more McIntosh tubes for this amp. Been more tube changes in this amp than I care to count. I bought it with the illusion I wouldn’t tube roll as I have my Woo amps for that. Could not have been more wrong.
Replaced the stock tubes on my unit with Tung Sol 12BH7A and RCA 12AT7's. No issues and been used daily now for months.
 
Dec 20, 2021 at 8:04 PM Post #644 of 890

u2u2

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How do the 6201's sound in the MHA200?
With headphones I find them more to my tastes than the stock tubes or CV4024. On the bright side when using IEMs. Need to get more time on them as the McIntosh power tubes were not up to par when I rolled the 6201s in. Foolishly I left them in till they red plated. My Sure SE846s, as an example, were unusable with the stock power tubes but are now decent but not great. My Utopias make me regret not ordering a few sets. The grade I bought are no longer available.
 
Dec 20, 2021 at 8:36 PM Post #645 of 890

Slim1970

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With headphones I find them more to my tastes than the stock tubes or CV4024. On the bright side when using IEMs. Need to get more time on them as the McIntosh power tubes were not up to par when I rolled the 6201s in. Foolishly I left them in till they red plated. My Sure SE846s, as an example, were unusable with the stock power tubes but are now decent but not great. My Utopias make me regret not ordering a few sets. The grade I bought are no longer available.
It seems that you're not the only one experiencing this red plate issue with the MHA200. I have a MHA200 coming soon, hence my interest into some of these issues. I'm looking at a set of Mullard 6201's as a tube option and I was curious to how they sound. The Utopia's is one of the headphones I'm looking forward to hearing with the MHA200.

Is the red plating a tube defect or is it something the MHA200 doing to cause it?
 

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