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McIntosh MC275 MK VI Clone

Alright, I finally opened mine up. I have no trimmers in my bias circuit. I'm pulling -69v/-69v and -65.5v/-66v. I can shuffle the tubes around any way I want and it's pretty much the same voltage. The progressively illuminating LEDs are strictly show. However, they did go to the bother of using Texas Instruments ICs to control the LED sequence. I'm seeing gray Vishay film capacitors right below the LED board.
 

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At leased he cathodes look like they are split, so each pair looks darn close bias wise.
I have a couple amps with auto bias and split cathodes instead of all four power tubes on one resistor.
 
ellum68 said:
Alright, I finally opened mine up. I have no trimmers in my bias circuit. I'm pulling -69v/-69v and -65.5v/-66v. I can shuffle the tubes around any way I want and it's pretty much the same voltage. The progressively illuminating LEDs are strictly show. However, they did go to the bother of using Texas Instruments ICs to control the LED sequence. I'm seeing gray Vishay film capacitors right below the LED board.
Click to expand...
Looks like they Update the Amp for LED sequence. Nice!!!! I see they are using Reg Electrolytics and removed the RIFA Electrolytics :idea:. I would consider upgrading to Films.

Did you purchase the Basic or Deluxe model? The basic model does not have the BAIS trimmers. I will contact the store to see what the 2023 model now has (LED board update).
 
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CohibaJoe said:
Looks like they Update the Amp for LED sequence. Nice!!!! I see they are using Reg Electrolytics and removed the RIFA Electrolytics :idea:. I would consider upgrading to Films.

Did you purchase the Basic or Deluxe model? The basic model does not have the BAIS trimmers. I will contact the store to see what the 2023 model now has (LED board update).
Click to expand...

This is where I got mine... Mcintosh Mc275 Vacuum Tube Powered Amplifier | Mcintosh Power Amplifiers - A-097 - Aliexpress

I went with what's listed as the "upgrade" version. I'm assuming that's the newest version along with an EH substitution on the KT88s. I can't find a single RIFA piece inside of mine. I think there's some kinda protection circuit where the power feeds hit the main board. I see yours has two transistor side by side. Mine has one transistor, a pair of caps below that, and then some kinda four legged critter below the caps. Last time I noticed, the real deal has a pair of fuses there. I'm probably at the thirty hour mark now and it's becoming a bona fide piece of kit in my book.

I've been meaning to bug you for the past few days with a question. What's your verdict on your C22 clone? I noticed you put a little bit of work into it. I don't mind having a recommended hit list of components to upgrade. I might go nuts having to track down weird stuff like that uneven balance control.
 
It's amazing how these can be made and make a profit.
I remember from a long time ago min of 30-35% profit needed just to stay in business.

Buying parts in bulk of course makes a big difference so with that being said, can you guys tell me what replacing just the tubes would cost you to put this in perspective? Just a rough estimate is fine as I have no Idea.

to deviate some if I may I have never looked at the website above but glad I did as I think these are the most handsome speakers I have ever seen with the grills on.

A 307 15 Inch Coaxial Floor Speaker Audiophile HiFi Loudspeaker Passive Speaker 6 8 Ohm/400W| | - AliExpress
Ha1ff1a5908524173ab9859ab5c89cb25y.png
 
ellum68 said:
Alright, I finally opened mine up. I have no trimmers in my bias circuit. I'm pulling -69v/-69v and -65.5v/-66v. I can shuffle the tubes around any way I want and it's pretty much the same voltage. The progressively illuminating LEDs are strictly show. However, they did go to the bother of using Texas Instruments ICs to control the LED sequence. I'm seeing gray Vishay film capacitors right below the LED board.
Click to expand...

Kinda impressed with the attention to detail on the LED sequence. Do they light up amber from left to right and then all green at once like they do in the authentic McIntosh version?
 
igorcaliente said:
Kinda impressed with the attention to detail on the LED sequence. Do they light up amber from left to right and then all green at once like they do in the authentic McIntosh version?
Click to expand...

Negatory. It's green LEDs only. I'm no guru, but I noted a pair of blue and yellow wires that land on pads labeled "12v" on the LED board. The Texas Instruments IC on the board appears to be a decade counter. It looks like the LEDs simply fire up on a timer once they get power. The tubes are warmed about the same time all the LEDs are lit. It's not as snazzy as the original's orange/green functionality though. I like the amp well enough that I'm building a second system in my basement based around it. ;)
 
NH-MAN said:
It's amazing how these can be made and make a profit.
I remember from a long time ago min of 30-35% profit needed just to stay in business.

Buying parts in bulk of course makes a big difference so with that being said, can you guys tell me what replacing just the tubes would cost you to put this in perspective? Just a rough estimate is fine as I have no Idea.

to deviate some if I may I have never looked at the website above but glad I did as I think these are the most handsome speakers I have ever seen with the grills on.

A 307 15 Inch Coaxial Floor Speaker Audiophile HiFi Loudspeaker Passive Speaker 6 8 Ohm/400W| | - AliExpress
Ha1ff1a5908524173ab9859ab5c89cb25y.png
Click to expand...

Tannoy copies now! About half the price of the originals.
 
I don't know, but I would imagine if you submitted proof you actually had a bad OPT on a genuine MC275 McIntosh would probably sell you one.

FWIW, Audioclassics has a listing at $1250 each.
 
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NH-MAN said:
It's amazing how these can be made and make a profit.
I remember from a long time ago min of 30-35% profit needed just to stay in business.

Buying parts in bulk of course makes a big difference so with that being said, can you guys tell me what replacing just the tubes would cost you to put this in perspective? Just a rough estimate is fine as I have no Idea.

to deviate some if I may I have never looked at the website above but glad I did as I think these are the most handsome speakers I have ever seen with the grills on.

A 307 15 Inch Coaxial Floor Speaker Audiophile HiFi Loudspeaker Passive Speaker 6 8 Ohm/400W| | - AliExpress
Ha1ff1a5908524173ab9859ab5c89cb25y.png
Click to expand...


with shipping...still an awful lot
 
Green tubes, lol. That was one of my many motivations to build my own clone. The MKIV clone board does NOT have any LEDS installed. Exact match to the MKIV MC275 board, strictly business.
 
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