AudioAficionado.org  

Go Back   AudioAficionado.org > Manufacturers Forums > McIntosh Audio

McIntosh Audio A Tradition of Excellence

Reply
 
Thread Tools Display Modes
  #1  
Old 10-06-2018, 02:37 PM
mati1979 mati1979 is online now
Senior Member
 
Join Date: Mar 2010
Posts: 520
Default MC275 MKVI and 12ax7

Hi. i have mc275 VI with all stock tubes.

i have "only" pair 12ax7 gold lion. and i see sockets

12ax7 : V3 and V5 phase inv.
12ax7 : V4 input preamp.

Where is it more convenient to replace? V3 and V5 (phase inverter) or only V4
Reply With Quote
  #2  
Old 10-10-2018, 06:09 PM
quartersaw quartersaw is offline
Junior Member
 
Join Date: Jan 2017
Posts: 14
Default

Quote:
Originally Posted by mati1979 View Post
Hi. i have mc275 VI with all stock tubes.

i have "only" pair 12ax7 gold lion. and i see sockets

12ax7 : V3 and V5 phase inv.
12ax7 : V4 input preamp.

Where is it more convenient to replace? V3 and V5 (phase inverter) or only V4
I'd use a NOS RCA 7025 in V4, and the Lions in V3, 5
Reply With Quote
  #3  
Old 10-17-2018, 12:20 PM
mati1979 mati1979 is online now
Senior Member
 
Join Date: Mar 2010
Posts: 520
Default

Quote:
Originally Posted by quartersaw View Post
I'd use a NOS RCA 7025 in V4,
I see that the most important sound change is when i replace V4.

when i replace V3 and V5 , I do not feel the change but V4 notable
Reply With Quote
  #4  
Old 10-25-2018, 08:20 PM
quartersaw quartersaw is offline
Junior Member
 
Join Date: Jan 2017
Posts: 14
Default

Quote:
Originally Posted by mati1979 View Post
I see that the most important sound change is when i replace V4.

when i replace V3 and V5 , I do not feel the change but V4 notable
Try some 5751's
Reply With Quote
  #5  
Old 10-28-2018, 07:59 AM
robinmtns's Avatar
robinmtns robinmtns is offline
Member
 
Join Date: Jun 2018
Location: Front Range, Colorado
Posts: 31
Default Depends On Which Inputs You Are Using

If you are using the unbalanced (RCA) inputs V4 is not in the circuit at all. And I find I get better imaging using the unbalanced inputs.

BTW you will see references on the audio boards claiming that the opposite is true, but this is opinion based on earlier versions of the reissued MC-275. I have also seen were McIntosh claimed that the Mk VI is using the same circuitry as the earlier versions, which seems me to be inaccurate.

I was hoping to attach a screenshot of the block diagram or schematic for the LE/MK VI but sadly I dont see how to do it. But both clearly show the left balanced signal path going thru one section of V4 and the right balanced signal path going thru the other section, before heading on to V3 and V5. And in the Service Manual McIntosh refers to V4 and the circuitry around it as a "Balanced Amplifier". The unbalanced signal path avoids this part of the circuit completely. If you would like to see it, PM me and I can send it to you.

So my advice would be to use the unbalanced inputs, use your tubes in V3 and V5. Put any working 12AX7 or equivalent in V4--as it may be needed to complete a heater circuit--but it will have 0 impact on your sound quality.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Audioaficionado.org tested by Norton Internet Security

All times are GMT -4. The time now is 03:45 PM.



Powered by vBulletin® Version 3.8.10
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
ęCopyright 2009-2018 AudioAficionado.org.Privately owned, All Rights Reserved.
Audio Aficionado Sponsors
AudioAficionado Subscriber
AudioAficionado Subscriber
Fortress
Fortress
Harmonic Resolution Systems
Harmonic Resolution Systems
Wyred4Sound
Wyred4Sound
Dragonfire Acoustics
Dragonfire Acoustics
GIK Acoustics
GIK Acoustics
Esoteric
Esoteric
AC Infinity
AC Infinity
JL Audio
JL Audio
Acoustic Sciences Corportation
Acoustic Sciences Corportation
Legend Audio & Video
Legend Audio & Video
Audio by E
Audio by E
Canton
Canton
Bryston
Bryston
WireWorld Cables
WireWorld Cables
Stillpoints
Stillpoints
Bricasti Design
Bricasti Design
Furutech
Furutech
Shunyata Research
Shunyata Research
Accuphase
Accuphase