McIntosh MC275 MK VI Clone
- Thread starter CohibaJoe
- Start date
jayvis
Addicted Member
Jeep does have a factory in India now, but I'd be shocked if they are actually shipping Wrangler bodies to Toledo, Ohio from India. I would guess that the total shipping, handling, and potential rework costs would prevent that from happening.
damacman
Resident Psycho
You missed the point entirely.
Lavane
Lunatic Member
Being shipped in bulk and shipped I'm flat packs probably saves space and some shipping costs. I used to unload containers.
Some if the stuff in them made me wonder how they made any profit. So the containers must not cost too much.
jayvis
Addicted Member
The packs wouldn't actually be flat unless you're talking about stamped blanks that haven't been formed and trimmed yet. As far as I know, the Toledo plant still has metal forming and the tooling needed for it. The raw material might come from India though.
Steve Hynes
New Member
The aliexpress sellers of Denafrips are all unauthorized. They are selling Chinese market equipment internationally against the dealership agreements with Denafrips and none sell the latest models, so its not clear who supplies the stock.
Long story short... No. I asked the seller and he had to contact the supplier. What I got a back appears to be simply a single channel from the real article. I can find that same picture elsewhere online by using a Google Image search.
Also, it's good to hear from you. I've noticed you've been following these knock-offs closely. I felt like a took an expensive gamble on this one and it actually paid off. In spite of using an auto-translator, the seller was helpful, prompt, and courteous. The amp got here in about ten days with zero damage (packed in an anvil case). The only flaw I could find anywhere was a switch labeled "STERED" on the faceplate. The seller said the misspelling was some kind of way skirting trademark issues. I'm not sure what help I can be circuit wise, but I can try. The biggest electronic thing I've done was build a replica of an 80w Fender Tweed Twin, adjusted its bias, and didn't burn the house down! Follow the chassis layout, twist the heater windings, and you can't go wrong!
As stupid as it may sound to others, I'm actually proud to have this thing in my stack. Just like that Tweed Twin I had, I know it's a knock off, but a well constructed knock off. I'm curious how @CohibaJoe has been getting along with the C22 knock off. It seems like that one needed a little help to bring it completely up to snuff.
As you and no doubt others on this thread know, I have a set of the Vanderveen Unity Coupled output transformers. I want to build an amp using these. I already did this once https://audiokarma.org/forums/index...rveen-vdv-1070-uc-output-transformers.937649/
This time I want to use 6L6GC's at higher B+ than the 6GM5's. To "short circuit" the process I have been looking fondly at the main circuit board for these at circa $330. I really want a blank board though so I can use my own parts. So far (after asking for a year to all the vendors I can find that offer a populated one) no one can supply that blank board.
Can I ask you a favor to ask the seller if he can locate a blank board?
This time I want to use 6L6GC's at higher B+ than the 6GM5's. To "short circuit" the process I have been looking fondly at the main circuit board for these at circa $330. I really want a blank board though so I can use my own parts. So far (after asking for a year to all the vendors I can find that offer a populated one) no one can supply that blank board.
Can I ask you a favor to ask the seller if he can locate a blank board?
At this point all the major tube amplifier topologies and circuit designs are so old that I can't imagine one can claim ownership of them. It's sort of a free for all. Making tube amps in 2023 is like making carbureted engines or something. The tech is so obsolete that it seems silly to be up in arms about copies.
If Ford was still building 70s Mustangs, would that give them a right to prevent replicas? Because that's essentially what McIntosh is doing with the MC275 -- continuing to produce a very old design that's long since entered the public domain.
If Ford was still building 70s Mustangs, would that give them a right to prevent replicas? Because that's essentially what McIntosh is doing with the MC275 -- continuing to produce a very old design that's long since entered the public domain.
I'm kind of tempted to whip up a board in KiCad. It can't be that hard, and I could probably sell them on Ebay. Board fab in China is crazy cheap nowadays. I reverse-engineered an ovenized voltage reference and I got the boards for less than $1 a piece, despite a weird form factor that required them to mill the board edges.
The Fender 5F6 Bassman is the best example I can think of. It was originally built with Western Electric and AT&T designs. It's been copied by Marshall, Vox, Peavy, etc. A 1:1 copy of the original 50s build is currently being made by Victoria Amps and it's better made product than the version Fender is currently selling. Hell, even I sourced parts from multiple different vendors and made a copy of its bigger brother, the 5F8. The toothpaste has long been let out of the tube.
I should probably shut up before another multi-page debate about ethics starts.
It's not about the right to prevent, the laws are what they are. The primary difference between this and a Mac is the hourly wage paid to the worker and where that money goes. The only reason to buy it instead of the Mac is because it's cheaper. Make the identical amp with the identical circuit in cosmetics that aren't a copy of a Mac and what is it? Another push-pull tube amp of which there are many, including many that are much cheaper.
I get that people will make that choice, others will prefer to support different business practices.
"Right to prevent" was a bad phrasing on my part because it is legalistic. I meant that typically there's no outcry about producing replicas of anything this old. IMO, the fact McIntosh still makes the MC275 shouldn't really factor into the calculus. They chose to continue manufacturing an old design, and I applaud them for it, but competing with clones comes with the territory. Of course people are welcome to disagree, just my 2c.
I "kind-of" compared them based on pics of the replica board and the Mk IV board in the MC275 Mk IV manual. It needs more study and verification.
My research documents are attached. There appear at least 3 issues.
1. There are two boards, one with gold traces on a dark (black?) board that comes with most? assembled MC275 replicas and then the populated board that is green color that can be bought separately.
2. The "gold board" has a trimmer, (circled in red). What is it for? Bias adjustment? I see no trimmer on the green board. There is also no trimmer on an original MC275 board as you can see below.
3. On the green board (I can't tell from the pics of the gold board) for D1 thru D9 they use a P6KE200A device rather than a 200V 1.5 watt zener as McIntosh specified. I'm not familiar with these devices so cannot comment on the reasoning here. It is called a "clamp diode". Does it behave like a zener?
Attachments
Last edited:
The 2 Trimmers adjusts the BIAS for the L/R KT88's. The Left side was at 65.5 V so I adjusted
at 61.5V. The Quad set should be Very Close to Balance.
Set it once with Balanced Quad KT88's at 61V-65V.
Last edited: