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Classic Audio MC Pro Phonostage Review
- Thread starter amirm
- Start date
Having designed a couple of phonostages myself, I find this very interesting. I like the reasoning behind your choices and the end result is also very impressive.
Still, I took a quite different approach. This is the power supply part of my RH RIAA 3.0. First of all, almost all the components are SMD and in this case the PSU is a switched capacitor up & inverting IC with built in LDO regulators. It also gives clean and steady output (+15 V / -15 V) without injecting any audible or measurable noise to the amplifier stages.
I believe this approach is practically maintenance free with usable service life of at least 20 years. There's no electrolytic capacitors to give you trouble.
Like your product this one is also hand-soldered with lead-free tin that contains silver. It also has an active mute to stop any noises entering the rest of the system (realized by A1 and A3 in the picture).
Well, I prefer full SMD design myself and I also hand solder them on 4-layer boards, no problem at all and don't have to cut those extra wires after soldering.
But THT design has its benefits too so it is more a matter of preference than anything else. I can of course say that fighting RF and other types of disturbances is easier with SMD but you can do it with THT as well if you know what you are doing. It is the board layout that is the most important detail.You are right about the PPS caps. The 2 % series is exactly what I'm using in my RIAA eq part. But 0.01 % thin film SMD resistors are very expensive. I don't think you really meant 0.01 % but rather 0.1 % which I'm using in all the amplifier sections? They are still quite expensive and cost more than typical 1 % metal film THT resistors.
There are two factors that decide how accurate your RIAA eq is:
- Circuit design. Wrongly calculated or inaccurate component values due to price reduction throw the eq accuracy immediately off.
- Parts tolerance. Even with 2 % caps and 0.1 % resistors, the RIAA curve can be off by several tenths of dB.
I just took a look at Michael's web site and was delighted to notice that his design philosophy matches my own in most cases. There are some differences too but perhaps I should start a thread of my own sometimes when I have time to avoid any more OT.
Generally I put the caps into matched groups but I've noticed that the accuracy of the '1%' through-hole resistors that I'm using is considerably better. The topology of the RIAA network as well (parallel) also plays a big part in averaging/mitigating component tolerance so the whole thing performs considerably better than you might expect in the worst case (which is a stastically unlikely outcome).
As far as using SMPS goes I don't see the need to introduce it, so it's better to do without it. If we're going to the trouble of using THT then it's better to use more readily-available parts to 'future proof' the design. There is of course the need to dissipate about 1.5W or so inside the enclosure at idle but in this case the internal temperature stays well below 40c so all good.
That is not to say that SMPS is necessarily a bad thing if you have a limited amount of space and thermal headroom, or need to convert what's coming in to your power supply to DC with great efficiency. For through-hole it's difficult to keep the loop sizes low enough to avoid trouble even with a fair amount of PCB space available. In regards to a 15V internal rail it can certainly work well, but you'll be limited to about 9.2V RMS output unless you use rail-to-rail opamps which significantly limit your choices. Although if you structure the gain stages so that the final stage applies the last couple of decibels of gain and uses a rail-to-rail device then you can push past 10V RMS while still using 5532/4s, 2068s or any other suitable op-amp for the front end.
If I had to use an SMPS I would use a 5V input type and bring the rails up to about +-17V with a suitable DC to DC arrangement, hopefully with some isolation...
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Are you kidding?
MM Pro By Michael Fidler Phono Stage Reviewed - Audio Appraisal
As far as I can determine, £600 is enough to buy you the finest moving magnet phono stage currently in production. And that phono stage is the MM Pro by Michael Fidler. I will stand by that stateme…
www.audioappraisal.com
AudioSceptic
Major Contributor
Has anyone also linked to their review of the MC Pro <https://www.audioappraisal.com/classic-audio-mc-pro-moving-coil-phono-stage-reviewed/>?MM Pro By Michael Fidler Phono Stage Reviewed - Audio Appraisal
As far as I can determine, £600 is enough to buy you the finest moving magnet phono stage currently in production. And that phono stage is the MM Pro by Michael Fidler. I will stand by that stateme…
AudioSceptic
Major Contributor
J
Could it be that things really are changing at last and honest, objective reviews, as we see at ASR, Archimago, and Audio Appraisal, are gaining ground against the borderline-dishonest delusional nonsense that's dominated for so long?
I have to quote this snippet from another review at that site.
Could it be that things really are changing at last and honest, objective reviews, as we see at ASR, Archimago, and Audio Appraisal, are gaining ground against the borderline-dishonest delusional nonsense that's dominated for so long?
AudioSceptic
Major Contributor
There is now a HP/pre-amp, the Spartan 30 <https://michaelfidler.com/products/spartan/spartan-30-headphone-amplifier/>. I'd prefer remote volume control for pre-amp use, but even just for the HP amp it's good value for SOTA performance.I notice a few people mentioning the price, I'm clueless about anything to do with vinyl so I had a look at mc phonostages on a popular retailer's website and ordered by price. Going from lowest (£64) to highest (£12,500!! although the penultimate was about 5k), £650 gets you about a quarter of the way down the page. I realise this isn't the best way to judge value but it's the best I could do without knowing what I'm looking at, it doesn't seem particularly outrageous to me. The product seems to be well designed and of high quality. It looks great in my opinion, especially inside.
I think it's worth mentioning that all of these products are hand built and soldered by one chap in his spare room in Kent (UK), then tested to spec on an analyser, in fact he even provides a picture of said state of the art spare room on his website:
So obviously there is going to be some premium compared to mass machine produced devices made in countries that have far lower costs all around. I would also expect this to have a good level of reliability (some thermal testing is in one of his latest facebook posts) and customer service. If anything goes wrong I know I can contact the guy and I haven't got to ship anything half way around the world, appreciate this isn't the case for those in the US/elsewhere.
I also think it's worth shouting out his website as there are very detailed explanations and measurements of each product as well as some quite lengthy articles for those interested: https://michaelfidler.com
He also has a Facebook page where he seems to be very transparent and willing to answer questions, as well as giving previews of upcoming stuff etc: https://www.facebook.com/mfidleraudio
I realise this probably reads like I'm a massive shill or have some sort of affiliation. Believe it or not I actually hadn't heard of him until googling from this review. I was just quite impressed as often a lot of these types of products made by a small company get into a lot of the subjective nonsense and don't measure that well.
Also will admit I'm a bit biased towards a small manufacturer and it being made somewhat locally! I don't have any use for this but will definitely keep an eye on the upcoming headphone amp.
Ooh thanks for the heads up, looks really nice. I noticed on a facebook comment he said there will probably be a pro series preamp with balanced inputs in 2025, perhaps that may have remote volume control?
It most certainly will!
Awesome, another thing to look forward to. Thanks for the response!
Very nice.
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I have similar experiences with Michael. He is very responsive on any question you ask or any comment you have. He is very open about his designs and choices he made. No BS at all!I notice a few people mentioning the price, I'm clueless about anything to do with vinyl so I had a look at mc phonostages on a popular retailer's website and ordered by price. Going from lowest (£64) to highest (£12,500!! although the penultimate was about 5k), £650 gets you about a quarter of the way down the page. I realise this isn't the best way to judge value but it's the best I could do without knowing what I'm looking at, it doesn't seem particularly outrageous to me. The product seems to be well designed and of high quality. It looks great in my opinion, especially inside.
I think it's worth mentioning that all of these products are hand built and soldered by one chap in his spare room in Kent (UK), then tested to spec on an analyser, in fact he even provides a picture of said state of the art spare room on his website:
So obviously there is going to be some premium compared to mass machine produced devices made in countries that have far lower costs all around. I would also expect this to have a good level of reliability (some thermal testing is in one of his latest facebook posts) and customer service. If anything goes wrong I know I can contact the guy and I haven't got to ship anything half way around the world, appreciate this isn't the case for those in the US/elsewhere.
I also think it's worth shouting out his website as there are very detailed explanations and measurements of each product as well as some quite lengthy articles for those interested: https://michaelfidler.com
He also has a Facebook page where he seems to be very transparent and willing to answer questions, as well as giving previews of upcoming stuff etc: https://www.facebook.com/mfidleraudio
I realise this probably reads like I'm a massive shill or have some sort of affiliation. Believe it or not I actually hadn't heard of him until googling from this review. I was just quite impressed as often a lot of these types of products made by a small company get into a lot of the subjective nonsense and don't measure that well.
Also will admit I'm a bit biased towards a small manufacturer and it being made somewhat locally! I don't have any use for this but will definitely keep an eye on the upcoming headphone amp.
AudioSceptic
Major Contributor
That will cost a *lot* more, though, > £1k?
Probably in the region of 2-2.5k, as it will feature 4 RCA inputs, 4 XLR inputs, defeatable tone controls, full size enclosure, relay volume control, level meters, stronger headphone amplifier...
AudioSceptic
Major Contributor
Someone suggested earlier in this thread that your products should come with transparent tops to show off the ultra clean circuitry. Seriously, might that be an option, or is it out of the question for cost and/or performance (EMF screening, etc.) reasons?
ban25
Major Contributor
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- Nov 5, 2022
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It would be cool indeed!
I did think about this a while ago, and it is possible to source EMI shielded custom glass pieces for surprisingly little as long as the quantity is in the triple digits. However, it seems that this would have to be at the top of the product to give a good view (maybe some space on a full-size enclosure on the front panel), which would probably get broken very easily when stacking units on top of each other. At the moment, dropping the cases just dents the corners a little, but doesn't render the units inoperable.
For the time being, it doesn't seem like a great idea to devote time to, but perhaps in the future, with a new enclosure style, it might be worth looking into again. At the moment, I'm just trying to concentrate on the electronics and keep the enclosure design relatively simple. For a 'high end' type of product it's probably a very good idea with a few strategically placed LEDs, but I'm not selling things for four figures (yet).
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