The £25,000 Pre-Amp that went Wrong - Tom Evans Mastergroove SR mkIII

If I had paid 500 for that I would be horrified at the build quality.

That unit seems suspect to me !
£20+ with part numbers filed off hahathat geeza Tom is laughin at the punters while on his boat in a place of paradise .
😂 i think after this video Tom might be less wealthy !

Who pays that much for a preamplifier?

Surely it should have 16mm2 cable to the output posts for loss less reproduction 😆

While the amp was not impressive Mark's work is.

Fantastic video!

I know nothing about electronics but now I want to know everything that you do. Please teach me.

"I pity the fool" that paid £25k for that as Mr T would say.

Fabulous video and a great watch, thanks.

Dat kost 25.000 pond .. veel te duur en slordig gebouwd ..

Great choice of record to test the pre-amp!

how much is pixy dust per gram

That was a great watch, nuts that a pre-amp would cost 25K, but fantastic to see you fix it

Excellent content as usual. My first thought when I saw the internals of this "audiophile" product was "you've got to be kidding!" The manufacturer has to be snickering "suckers!" to everyone who shells out $25K for that thing.

Amazing, it might as well be magic!

Biggest snake oil that you ever had in there 😁, great job

Some high end build quality.

It looks like someone had an interesting but laborious idea (paralleling the gain stages, select-on-test components), built a prototype.
Then for the board architecture and packaging said "that'll do".
There's a big gap between making 1, and having a business that makes repeatable high quality products.

what did the dip switches on the back do?

Sir, I am stunned by your level of technical knowledge and ability. We need you and others like you (if there are any!) to impart your knowledge to young students. Bring back technical colleges.

What difference will the black cable tie make to the sound?

Did we find out what all the DIP switches are for?

Khruangbin on vinyl for the test?!? Nice!!

Hi Mark,
Big fan of you channel and exceptional work. I have a vintage Marantz tuner from early 70s which doesn't work and needs repair. Will you be able to do it?
Kind Regards,
Dimitar

You are a genius! Well done! :)

Is it still good practice to use tantalum capacitors in audio? They absorb moisture and there ESR decreases rapidly.

hi : I have a Marantz model 16 . The transistor sj3680 is out of order, but I don't know what replacement I should use . If possible, guide me, great man.

what would the sum of the components cost to build this?

Tom Evans - remember him arguing with George Martin about digital clocks for audio at Air Stuido Lyndhurst - great guy and good buddy of John Bamford (RIP) ex Pioneer - good video 🙂

"25,000"

shocking work for the money. Edit/ I think the care repairing the machine I would value more than the machine itself. great video mark :)

Ahhh audiophiles, keeping the worlds supply of snake oil at low levels since the 1950's.

I was wondering what justified the 25k price tag but then it all became clear when I realised it had cardboard shims to minimise the rattle from the shit case design.

I can't believe you didn't even use oxygen free cables

I was building hi spec preamps 45 years ago. They had low noise, high gain and very low distortion. They did not cost much. The boxes cost more than the electronic components.

Incredible work 👍

Great work, as usual. Cheers Mark! 🍻

There is some science behind loading the op amp's output with a current source. The idea is to "pre-heat" the bias of the BJTs that are in there, which will force the op amp to operate in class A all the time. In theory, this will eliminate the possibility of any switching noise or crossover distortion. I've done it a few times in my own designs using a couple JFETs in a cascoded configuration. If that's how he did it then we must have read the same book. Does it make any difference? Well, I use decent op amps so their noise level without the trick is already orders of magnitude lower than what my test equipment is capable of measuring. Perhaps if I do a circuit with many series op amp stages—like an active filter or something— I can do one with the trick globally and one without the trick globally and compare global noise measurements. I don't expect a significant decrease in noise but there will definitely be a significant increase in price as those JFETs are expensive little beasties. Think of it as one of those "1% better" situations. You try it after you've already optimized the rest of your circuit and you just can't resist shaving tiny bits off here and there to try and turn that .001 spec into a .0007. So if your circuit design looks like a 12-year-old's science fair project, with circuit boards flopping around in the chassis and your stand-offs are more like fall-offs, you have no business throwing money at "1% better" solutions. 😂 At that price point? C'mon man. Priorities.

At least 95% of the world isn't affected because they can't afford such things.

Hey mark, and everyone in the comments. i have a 5.1channel panasonic XR30 amp type thing ig, and i'd love to use it for a simrig some day, But i got it from my neighbor not working, theres no audio output. on neither the jack at the front or the terminals at the back, i thought maybe its input related... but it seems when i hold my fingers on the cable tip of the 3.5MM to RCA, it seems to regocnize that theres static and gives me an message saying that (i forgot it..) But it doesent show anything else on issues.. i have no other eqiupment than a small cheap and fun multimeter, and a soldering iron lol.. Would love to get it working (im already broke enough cant buy me a 30 euros used one..)

wery nice job

You are actually a genius 💪💪🙏

Khruangbin! A fine taste, sir. :)

you've just made a silk purse from a sows ear, incredible craftsmanship.

Tested with khruangbin... Just icing and sherry on the cake. Thank you

Wow, I wouldn't mind spending a few days/weeks with him. Absolutely brilliant. If he had been my mentor when I started as an apprentice I would not have given up and gone digging holes instead. Just WOW.

Fortunately, we had the good sense to aim the microwave energy away from us.

Audiophile snake oil.

That £25k went to labour costs to remove all those component serial numbers and capping the other parts ‘for insulation’.