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  1. W

    MC 275 Blown Resistor

    Hmm I wonder if the spare 'used' tubes it came with might have been removed in the first place because they were faulty and had intermittent plate shorts.....it certainly might explain why you have had several failures in a row. I have had a few KT88 failures in mk IV's too - in 4000 hours...
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    McIntosh MC275 Versions

    Haven't the 50th Anniversary and MkVI also eliminated the tertiary feedback winding from the output transformer, taking the feedback direct from the speaker winding ? If so, this is an interesting development as the MkIV and V applied 'balanced' feedback to the two halves of the driving...
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    Replace speaker connectors of MC275 Mk.IV?

    Please don't do it....that would be a near criminal act of vandalism to your poor MkIV ! The company Prelude Audio of 125 Mohawk Ave, Scotia, New York manufactured custom high quality adaptors for those with stadard spade cables - these consisted of a few inches of cable connected to a...
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    MC275 mark IV - one of 12AX7 flashes on startup..

    Hi, the heaters of V1 and V2 run in series from a 24 volt dc supply, flashing of the heater is perfectly normal and occurs when some of the heater wire is exposed and isn't fully coated by cathode material. This happens as part of design (original Mullard) or just manufacturing tolerances. It...
  5. W

    Where to Rack Mc275?

    Hi, 10" sounds like it might a little too tight for space (particularly as the rack is wooden and will likely get quite hot immediately above the output tubes). I have a pair of MC275's stacked vertically on a glass rack (similarly open all sides) with 12" spacing and they seem happy enough...
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    NEW! 50th Anniversary Mc275

    Those rather unattractive ventilation slots (of the picture above with blue leds) don't appear in the overhead shot of the unit on the McIntosh website. Anyone have any ideas why there appear to be two variants, with and without additional ventilation slots ?
  7. W

    Tube Question

    Hi, it's likely you are just seeing a bit more of the heater filament than in the other three tubes due to variations in construction, have a good look at the cold tubes and see if you can see any differences in the length of exposed heater that might account for it...
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    NEW! 50th Anniversary Mc275

    I agree, to my eyes at least it is pretty horrendous in gold and those tube lights just add to the fairground effect...still, I imagine McIntosh know their markets and it is probably going to get good publicity exactly because it is so...ahem...'eye-catching' which will probably help boost sales...
  9. W

    digital room correction

    How about trying the Behringer Ultra Curve Pro DEQ2496 and the matching measurement microphone - don't know what it costs in the U.S, but I would think it is within your price range: http://www.behringer.com/EN/Products/DEQ2496.aspx...
  10. W

    MC 275 Blowing Fuses

    Hi, I am assuming it is the externally accessible mains fuse that keeps blowing. It is most likely to be one of the KT88's at fault (but turning a hot amp off and then on in quick succession is virtually guaranteed to blow the mains fuse - allow it a minute or so to cool before switching...
  11. W

    5751 Tubes in MC275 IV filament problems ?

    Cheers Ron, I have done the maths and the filament voltage using the 24 volt DC supply -is +2% on the 12AT7 (which is fine) and -13 % on the 5751 at 11.1 volts approx (which is outside design limits but not by too much so it might work ok). The only other option is to put only one...
  12. W

    5751 Tubes in MC275 IV filament problems ?

    Thanks for the reply Ron, but won't putting a 12AT7 150 ma filament in series with a 5751 175 ma filament across 24 v DC as in V5 and V6 cause problems by under-running one and over-running the other filament ?
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    5751 Tubes in MC275 IV filament problems ?

    Hi All, Any advice here would be appreciated. I have a large stock of GE 5751 and 12AX7WA tubes to use in my MC275 mk IV pair. I know the different gain of the 5751 is no problem in the MC275 and it can substitute for the 12AX7A (McIntosh themselves have confirmed this). The problem...
  14. W

    mc275 - too good to be true

    It's not even the same amp in all the photos - the glowing tube photo has screened logos showing on the small tubes - who knows, maybe the kind Lithuanian gentleman will send you both amps for the same price :scratch2:
  15. W

    Stereophile review of the MC275 online

    Hi, cheers for the heads-up on that - good review, and I have been waiting to see if Stereophile would do a full technical test of the 275.
  16. W

    McIntosh MC275 Versions

    Hi, my understanding is that leaded solder is still used by the military because it suppresses the formation of 'tin-whiskers' which can damage delicate solid state circuitry by shorting out components or pcb tracks. This is an issue where reliability is essential and where the circuit energy...
  17. W

    My MC275 nameplates are different

    It's probably easy, but I bet it is really hard to notice the difference - I couldn't believe mine were actually different when I looked at them up close - is the difference between yours that noticeable ?
  18. W

    My MC275 nameplates are different

    Hi, I have two Mk IV's - one has what looks like a dull silver coloured paint on the logo, and the other looks like it has a (slightly shinier) metal infill brushed horizontally.........both are stacked one above the other and I had never noticed any difference in them until I saw your post...
  19. W

    why are those Mcintosh interconnects only sold on ebay from Hong Kong?

    Expensive for counterfeits though - some sellers are asking nearly $200 for interconnects !
  20. W

    McIntosh MC275 Serial Number VN 1824 - Can You Identify It?

    I have pm you with some details.
  21. W

    MC275 blowing fuses

    Hi, Am I right in thinking your amp has blown several fuses in quick succession so you probably have an intermittent short in a KT88 ? In order to see which KT88 is causing the problem you can try replacing the fuse then watch the amp very carefully in a darkened room when you next...
  22. W

    MC275 4 or 8 ohm taps for SF Guarneri Memento's

    You won't break the amp on either tap - try experimenting and see what sounds best to you.
  23. W

    MC275 MkV - How does single-ended sound compared to balanced?

    Hi Harry, I am sorry but I don't know the answer, maybe someone with a better knowledge of the particular McIntosh gear knows the answer ? I wouldn't get too hung up over whether something is 'fully' balanced or not so long as it is well-designed. Poorly designed kit trying to jump on the...
  24. W

    MC275 MkV - How does single-ended sound compared to balanced?

    Hi, 'Fully balanced' is when the circuit accepts a balanced signal on the XLR input, handles it in balanced form (which involves 'mirror image' circuitry so maintaining its common-mode noise rejection), and outputs it in balanced form. Equipment that is not 'fully balanced' may...
  25. W

    MC275 MkV - How does single-ended sound compared to balanced?

    Hi, it would seem a shame to add another pre-amp to the chain since the PS Audio unit seems to be a DAC and pre-amp in one - and a very good one from the look of it. I was going to suggest you try the RCA out of your DAC in case the balancing arrangement on the PS audio unit was not of good...
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