Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Power supply upgrade

Don't worry, the original power supply will fail soon...

How long will mine last? and no string comments!

Shaun

I am not sure, but I am under the impression that most of the power supply problems were in the US? This is just based on my recollection of people posting about power supply problems.

There are certainly some gains to be made on the supply side of the SMPS... however, are you using any analogue features of the unit? If it's digital running only then I'd refrain as the most significant gains are to be made in the analogue domain.

You may actually lose overall as one downside would be mains supply voltage variations which would now affect the unit in the absence of a mains regenerator like my PPP.

I'd consider how to get very clean power to the SMPS, also EMI/RFI shielding inside the unit. My Weiss Medea DAC had a box within a box to minimise this. I've heard some use of a special paper but can't remember enough to comment and haven't used it myself yet...

This is one area where (IMHO) the Soolool Control 15 unit could be vastly improved - the audio board with its clocks etc sits directly above a CD ROM drive and adjacent to a spinning hard drive.... no shielding present at all...

Can anyone remember how much a new SMPS from Meridian costs?

This is an extract of the spec for the old PSU (I couldn�t find anything for the new one very easily):

The output performance is typically 1% for the key line and load regulation, noise and ripple parameters.

This is very typical for modern SMPS�s, but is at least 20 � 30 times worse than a good linear supply. Based on what I�ve seen from various searches, I�d expect an SMPS to that spec to cost 30 � 50, and a linear supply 100 � 200. (The currency is whatever your currency is � GBP, USD or Euro � the number tends to stay the same).

So a linear PSU is more expensive, but I was wondering how it would compare with a new PSU from Meridian?

Nick

I am quite into DIY and the difference the PS may have is sometimes surprising. The Meridian gear is quite well designed (the final boards I mean, with decent local decoupling and so on) so they can put those ugly/cheap SMPS's in most of their gear without (much) fear.
As you know the 8xx series have an extra board after the SMPS (just some cheap regulators and some more filtration with decent caps) but this is still not much compared to a good regulated PS. And the old 500 series (like 568) used linear PS with quite good capacitors and linear regulators (they stay quite warm even in standby), see internal pics on Duncan's web. If I remember correctly, the G02 is the only 'new' M gear with a linear PS (and nice toroidal too), besides the speakers off course.
An example: in my Buffalo DAC I use a Sigma22 (google please) bipolar PS for the analog out stage and the difference this makes to the sound compared to a 'good' standard linear regulator (78xx+79xx chips) is not small. And the 'good' regulator is quite ahead of what is inside our M gear, so...
One day (I hope) I will have time (and courage) to do this to my 861 (I am even considering a G68 to experiment).
And I always wondered how far the SQ of my 808.2 may be pushed this way.
Something I know is, if the day arrives to my 861 PS, I know what I will NOT put inside it

(edited)
See Nick's post above: inside multiK$ gear there is a 20? pound power supply. Most audio gur�s will tell you the first limiting factor of any audio gear (be it CD plater, DAC, preamp or power amp) is inside the power supply... Hey, fingers up to Meridian to find a decent smps and make it work on a such high level as we all know around here!

Nick,

The PSU Meridian currently fit to both the 861 and the G68 is the XP ECM40UT31 which is widely available for around �30 - I bought and fitted one to my G68 about 8 weeks ago.

Fairly recently Meridian charged Malcolm W �250 to supply the same type of PSU to his dealer, Phase 3, which they then installed. Phase 3 did this for no additional charge of their own, they just passed M's cost through. FYI the PSU manaufacturer offers a 3 year warranty but Meridian did not pass the benefit of this through to Malcolm.

Cheers, Roger.

Is this it? Seem cheap!

How hard can it be, to install that!! I cannot believe that all these upgrade companies haven't come up with some great upgraded PS for the Meridian units... Seems like an obvious market.

For the record, the 5-series equipment used linear supplies, and so did the G01, G02 and G07, but all the other G series and 8 series used SMPS - even the 808.3.

Incidentally, the ECM40UT31 PSU in the Octopart link above is an SMPS where the line regulation, load regulation, ripple & noise are all 1%. Same as every other modern SMPS.

Looking more closely at the secondary supply board in the 861, it looks like that's just a filter. It only has passive components - there are no secondary regulation stages.

I have a lot of faith in Meridian when it comes to developing for the best sound quality (if not ease of installation or customer support). I can't believe they would have compromised such large, heavy and expensive processors such as the G68 & 861 by fitting SMPS, when a linear PSU might have been better. However, the margin of superiority of linear over switching supplies surprised me, and I'm definitely going to try it out.

Simply modifying some equipment, then listening to it afterwards (perhaps a long time afterwards) isn't a reliable way to hear any improvement. If you want to hear an improvement, you probably will. A blind test of two units side-by-side is much more challenging - and convincing. To this end, I've gone mad, and acquired another 861 for experimentation. This one is a V2, rather than a V4, but I thought it might make an instructive comparison. I preferred the V4 to the V2 in previous shoot-outs, so the challenge is to make the V2 sound better - I think that would be very meaningful.



After a few listening sessions I thought I�d capture my thoughts on base-lining the stock 861v2 with the 861v4, before I forget everything. Using the v4 as the reference is important, so I can be confident in judging whether the power supply has any impact on the v2. If they sounded the same before and after, the comparison would be worthless.

And to begin with, they did seem to sound the same. I tried to set them up identically, and even used the same output cards � OA02. These seem to have a significant bearing on the sound, certainly on a superficial level � tonal characteristics etc. When you take the D to A conversion out of the equation, the differences between processors are more subtle.

I think this is why ABX tests are often poor discriminators, and make everything sound the same. If you keep hopping and skipping between equipment, you don�t get to dig into the core of the music, in the way that you can with extended listening. And it was only after a longer time that the improvement of the v4 became clear.

The v2 certainly sounded good, but the presentation was flatter, more forward and two-dimensional. The v4 had more resolution, and initially seemed more analytical, while the v2 was a bit more superficial, but had good energy, drive and rhythm. However, the v4 was at the same time more relaxing and more exciting, and had better micro-detail, so the soundstage was deeper, and better fleshed-out. If playing music is like painting a colour-by-numbers picture, then the v4 was using more colours.

Its getting interesting, but there's more to come...

Nick

Proper dedication!

Now are you going to have the linear PSU inside the 861 or in a separate enclosure for further improvements?

I remember experimenting with power supplies for an external phono amp (using Naim boards), on paper it only needed 0.1A of current per board.
I went from 0.5A to 1A and then to 5A per board, sound quality improvements were easily heard each step.
The best and final power supply I used was made up of Yuasa sealed lead acid batteries (peak current of about 20A), measurably better as there was no ripple* as there was no 100Hz capacitor recharge cycle.

Good luck and have fun!

Steve.

* ripple in the power supply is easily heard as low frequency hum, especially important when your circuits are amplifying microvolt signals from phono cartridges.

There are different "DC-filter boards" -thats after the SPS.
The 861 have only one amp maybe for power on or temperatur control.
The 800 Dc board have a 3 pin voltage regulator.
all other circuits are passive on that board.
The new PS is the
ECM40UT31 from XPPower
link to PS data
Its a 40 Watt switching PS and have 1% peak to peak hum/noise thats at 12VDc are 120mV.That sounds good in the first impression and look to the older PS this is better.When you calculate that is a signal/noise ratio of 100(1%) and thats 40dB-that is "not impressive".
Of coarse the DC-filter board improve that,but I want just give a "feeling" for data here.The hum/noise is one factor,more important is the "impedance".Thats is the resistance with different frequencies.So the best would be, that for every frequency the resistance is equal, then you have no or equal influence to the frequency response.That is important in every amplifier as the current flow is starting from the PS over the preamp and further the power amp circuit(all in one device ) further to the speaker and back to the PS.So the PS and the AC/DC circuit determinates HOW the current is influenced(beside all other componenets in the chain).
What I want to say here is, that not only the hum/noise is the important factor to select a "better" PS.
SPS generates do their function more noise(switching), but that are basically easier to controll. Linear PS not only generate line frequencis as it mybe sounds logic,they are generate also high frequency noise.The transformer,diode(rectifier) and charge capacitor are a oscillator-there are good explainations for that on the net. So finally the construction itself and selecting proper parts(what should be included in a "good design") determinates the sound quality besides their basic goal to supply a stable and noise free DC voltage.
Impedance you dont get from a datasheet and they are not really helpfull as allways there is a circuit behind that in summary with the PS, is the impedance what the "audio circuit" will "see".
Select a battery is not "easy",watch here for the Impedance,depending on the type(Pb,NiCd,Lithium...) and HOW their inner construction is), there are big differencies here.
So working trustfull,you have to look for the spec,have to make fastidiously measurement(which expensive equipment),
but finally your ear/musical taste decide what you like....
I know the whole post mabe not practical helpfull, i just want to make a little sensitive about that sophisticated chapter.

Robert

I did not know about the 8xx extra filter variants (my 861 and 802 had the same, with one LM317 regulator besides the extra filtering capacitors).


Wow VERY interesting Nick!!


Now some 'practical' info...

-There are lots of sites with PS explained, but this little piece os software is very helpful when you try to better existing PS (or designing from scratch):
http://www.duncanamps.com/psud2/index.html

-A fine regulator (there is a bipolar version too): http://www.twistedpearaudio.com/power/placid.aspx

-And something good and already (almost) assembled in this good seller: http://www.audiophonics.fr/audiogd-psu09-alimentation-stabilisee-discrete-512v-800ma-p-5736.html

Regards,

Josep

PD. After your succesful reviver, Robert, maybe you can do something about all this!