Classic Audio MC Pro Phonostage Review

[EJ3]

I regret not buying an MC Pro when I had the chance. Now I’ll have to keep a close eye on the next batch from @Michael Fidler ! It feels like waiting in line for tickets to a sold-out concert.

Back before internet times, I presume!

 

[Angsty]

same here...

Seeing what MF did with the Spartan series, I’d bet the next version will be better than the first.

 

[Michael Fidler]

Seeing what MF did with the Spartan series, I’d bet the next version will be better than the first.

Or at least more scale-able! I'll post a picture of the new board once it's up and running.

 

[EJ3]

Or at least more scale-able! I'll post a picture of the new board once it's up and running.

I have nothing in the MC fight but I like that you are doing this.

 

[Michael Fidler]

I have nothing in the MC fight but I like that you are doing this.

It's going to take a fair few hours to do the layout justice. All the blocks in the schematic are done and dusted. 235 components on the board!

The original had 135, so almost a 75% increase in parts count, although no more incoming capacitor QC required. Hopefully, the smaller footprints of the 3216 caps and 0204 resistors will help fit it onto the same board size, so I can stick the prototype in the same enclosure.

 

[MaxwellsEq]

It's going to take a fair few hours to do the layout justice. All the blocks in the schematic are done and dusted. 235 components on the board!

The original had 135, so almost a 75% increase in parts count, although no more incoming capacitor QC required. Hopefully, the smaller footprints of the 3216 caps and 0204 resistors will help fit it onto the same board size, so I can stick the prototype in the same enclosure.

Blimey! Will you be able to make a profit?

 

[Michael Fidler]

Blimey! Will you be able to make a profit?

If it can be automated, it should be OK. No time sifting through film caps matching them up!

 

[cgallery]

I haven't read the entire twenty pages so maybe this was addressed, but what is the point of having two LF filtering approaches. It would seem one, or the other, would be sufficient?

 

[Michael Fidler]

I haven't read the entire twenty pages so maybe this was addressed, but what is the point of having two LF filtering approaches. It would seem one, or the other, would be sufficient?

The subsonic filter deals with cutting out tone-arm resonances/record warps/surface effects below 20Hz, while the LF XFEED function reduces stereo field noise below 100Hz or so. They both do different things: one operates outside the audio band, the other within it.

 

[Angsty]

It's going to take a fair few hours to do the layout justice. All the blocks in the schematic are done and dusted. 235 components on the board!

The original had 135, so almost a 75% increase in parts count, although no more incoming capacitor QC required. Hopefully, the smaller footprints of the 3216 caps and 0204 resistors will help fit it onto the same board size, so I can stick the prototype in the same enclosure.

"Super-bombproof"!!

 

[Michael Fidler]

"Super-bombproof"!!

TVS + polyfuse on the input side, shunt diodes across first caps in the voltage-doubler "but how does my 24V AC Rega power adaptor SOUND with this unit". Usually I can "best of luck with your next choice" those guys before it comes to payment, but occasionally one will get through, or some predatory little reptile (almost always in the UK) will try and foist some dubious 'upgrade' upon them that results in destruction + it's still remotely possible to connect the wrong power adaptor by accident.

Also, strong RF filters on input and output. I designed the original to withstand about 5 times what you might expect from marginal EMC-passing equipment in the near vicinity, but it's still not quite enough for about 3% of cases, especially using exotic cartridges of the very low output type. In close enough proximity (60cm or so), dodgy LED lights from Aliexpress and ethernet-over-power adapters can yield enough RF at the input to provoke detection, especially if exotic cables are being used. Having a massively high gain doesn't help much, either. This does also affect the vast majority of contemporary preamps, but it would be good to make it much more resilient.

 

[cgallery]

The subsonic filter deals with cutting out tone-arm resonances/record warps/surface effects below 20Hz, while the LF XFEED function reduces stereo field noise below 100Hz or so. They both do different things: one operates outside the audio band, the other within it.

Can you give an example of where there the LF XFEED helps, what sort of album or recording issue it addresses, that the subsonic doesn't?

I guess I'm not familiar with issues between 20 and 100Hz is what I'm saying.

 

[Michael Fidler]

Can you give an example of where there the LF XFEED helps, what sort of album or recording issue it addresses, that the subsonic doesn't?

I guess I'm not familiar with issues between 20 and 100Hz is what I'm saying.

Full description here...

https://michaelfidler.com/products/pro/mc-pro-moving-coil-phono-stage/#7

 

[cgallery]

Thank you @Michael Fidler, that was very informative.

 

[Michael Fidler]

RE: Bombproofing...

Here's one that got Rega'd today! Sadly can happen even to the best of customers.

 

[cgallery]

I recall when Panasonic and Sony (and everyone else) started making their adapters with proprietary tip sizes/configurations so users couldn't blow-up their gear any more.

 

[Michael Fidler]

I recall when Panasonic and Sony (and everyone else) started making their adapters with proprietary tip sizes/configurations so users couldn't blow-up their gear any more.

Sadly it's virtually impossible to get custom connectors made that would be cost-efficient while precluding misconnection of dodgy PSUs.

I think it's probably better to just add the internal components to deal with it - that way you also have protection against severe power surges of catastrophic proportions.

 

[ban25]

RE: Bombproofing...

Here's one that got Rega'd today! Sadly can happen even to the best of customers.

Jeez. I even forgot that there's no grounding lug on Rega TTs and you have to (presumably?) use their pre-amps in order to ground the tonearm. Ridiculous!

 

[Michael Fidler]

Jeez. I even forgot that there's no grounding lug on Rega TTs and you have to (presumably?) use their pre-amps in order to ground the tonearm. Ridiculous!

I wish! Then I'd be left alone... Regrettably, they hum equally well with all brands, depending on which power strip they're plugged into, the length of a piece of string, and which position the moon is in.

It's such a simple fix - just use a conductive coating on the glass platter to shield the motor and add the ground wire. Total cost: less than a cup of coffee!

Rega actually has a good reason for doing this as they put the ground on the left channel audio cable*. They believe doing it this way sounds better** and it is hard to argue with their decades of experience***.

*Cost-cutting measure
**Unfalsifiable claim
***Appeal to authority/chronology

Forgive me if I don't interpret this charitably . The internet is littered with furious forum users and people who've tried the product and have given ample feedback that the company needs to change its ways. Personally, when I've dealt with clients who have Rega setups, it causes an issue half of the time, all for a tiny little wire...

Rega: Just say anything, make anything up, say you've changed the electrical alignment of the design or some other BS, but fit the ground wire!

 

[JP]

Affirms why I don’t work on ‘tables for others anymore. Not enough money in the world.