[StevenACNJ]

A few months ago I decided to look around for a
new Pre/Pro. I have been using a Lexicon MC12
Ver 3.0. I liked the Lex but got the upgrade
itch (had the Lex for 2 years) and decided to
scratch the itch with a Meridian G68.

A never used Merdian G68ADV (silver) came up on
AudioGon, from a fairly local seller. Unit was
absolutely in brand new condition, was in fact
never used, could do a local face to face
transaction, so purchase was a no brainer.

Put the Lex up for sale on AudioGon and sold it
3 weeks later. Net deal for brand new Meridian
G68 ADV was $500 out of pocket. Not bad.

When I got the Meridian had to flash it up to
the newest firmware version. Also, prior to
installation, I like to open up my pre/pro's
and take a look at the inside layout &
components, also apply some Pro Gold to all
possible internal connections.

Right about now, I'll bet your wondering, why
is this goofball posting this in the lab? Well, here's why.

After opening up the G68, I noticed two things
which I didn't like: 1. The IEC was actually an
iec, power switch, & built in filter combo (not
good) 2. The entire power supply unit was very
small (3x4.5") & cheap looking.

The power supply unit looked familiar and I
knew that I previously saw pictures of it, but
couldn't remember where. I jotted down make &
model numbers of both units.

I buttoned up the G68, configured it with my
laptop & Meridian M-Config program which is
pretty cool to use. Installed it and let it run to burn in, remember it was never used.

After about a month, I began to intently listen
for evaluation of sound quality. Sound was
good, not as good as the Lex, was kind of
polite sounding. 1 & 2 above were in my mind
and I decided to do something about it.

Searched on Google and was able to find PDF spec sheets on both the power supply & IEC/filter units. Both were current models sourced from 3rd party electronic manufacturers. I am positive they are both very inexpensive. I have seen this power supply somewhere before (yes repeat).

For power conditioning of my front end, I use a
RS Haley, so I knew that the factory IEC/filter
unit was not needed & had to go. I decided to tackle this first.

One problem in changing the factory IEC unit
out was that it would require a new rear plate
to hold a new IEC & switch. I had a nice
aluminum plate (thanks Gordy), so out came the
Dremel and drill. Fashioned up a new plate (approximately 4" long & 1.5" wide) and installed a cryo treated Acme IEC & single
throw dual pole switch.

Wired everything up exactly as done by the Meridian factory & flipped the switch for a power up test. Very nerve wracking, slow moving, point in time waiting to see smoke, burning, etc - but nope, powered up like normal. Let it run for a while checking to see if power supply over heated or any other problems. Nope all was perfect.

Next got the G68 installed back in my HT system powered everything up, and within about a minute of listening, picked my chin up off the floor.
Dynamics really kicked in, tight tunefull bass (could feel it in your gut even at  relatively low listening levels), phrat (didnt have any previously) wonderful high & wide soundstage, air, detail, perfect top end. Huge difference - day & night type of change for the better. That IEC/filter contraption was just choking the crap out of the power supply.

My tweaked Meridian G68 is the best pre/pro I ever heard & I have owned the following: Outlaw (dont remeber model), B&K Ref30, EAD Theatermaster 8000, Theta CBII (superior dacs), Lexicon MC12 Ver 3. I also have heard the Krell HTS 7.1. Lex was best of this bunch.

I am floored by this tweak. Not exactly for the faint of heart but not that tough either.

Next up - power supply: I know I have seen this before and after some looking on the net found what I was looking for. www.mauimods.com - Yes Anthony's Tact modded power supply is the exact same power supply as the Meridian factory. Sent pics of the Meridian factory supply &
manufacturer's PDF spec sheet to Anthony and his response was that it is 100% the same.

Received Anthony's best power supply on Friday, installed it Saturday am. Exact fit, connectors were an exact match too. Flipped the power switch and my G68 came to life.

Reinstalled the G68 in my HT system, powered up, and immediate impression was wow!

Here's what I emailed to Anthony this am: "The positive changes that your power supply made over and above my previous removal of the IEC/filter combo (which was a big change for the better): better dynamics, greater detail. more air, bass punch, overall more refined sound. All this with only 24 hrs run time on the new power supply."

More after it burnes in.  

[Levi]

Congrats on the new and modified MeridianG68!

Have you considered working for Meridian?  You will make a good asset to them.  Create an "Audiophile" department.  Keep us informed!

[rblnr]

Am intrigued by the mods., but we have very different ears.  I own a G68AXV now, and owned an MC12Bv3 prior to it.  The 'stock' G68 is far superior for music to the Lex. IMO.

[zybar]

Am intrigued by the mods., but we have very different ears.  I own a G68AXV now, and owned an MC12Bv3 prior to it.  The 'stock' G68 is far superior for music to the Lex. IMO.

That's how my ears heard it as well.

The Lex kicks serious ass for HT but has always been lacking when used for 2 channel listening.

Can't say I ever understood why, but it has been that way since the DC-1 days...

George

[StevenACNJ]

My Lex MC12 V3.0 was the RCA version not the "B" balanced version. My Meridian G68 ADV is also an RCA (not balanced) version. Dont know if that would make a difference.

Just a clarification: my comparison of the Lex MC 12 & Meridian G68 was not done side by side. Once I pulled out the Lex to sell it, I did not put it back in for comparison. Also the Meridian was brand new, never configured, never used, so it needed to break in. My listening impressions of the G68, after about a month of break in, was based upon a mix of HT & Music.

Regardless of what I stated previously, immediately (no burn in time)after the above mods, the Meridian G68 is now absolutely killer good.

Zybar, it must be similiar to what you experienced when you upgraded the power supply in your Tact pre-amp.

[MauiMods]

If I remember correct, the Lexicon uses a 15 , 5 , -15 supply,
that could be easy modded.

[StevenACNJ]

This thread spilled over to the Meridian Forum and really stirred up a hornet's nest - Yikes!  

http://www.meridianunplugged.com/ubb/ultimatebb.php?ubb=get_topic;f=7;t=000514

They dont like the notion that Anythony's wonderful power supply could possibly be better than the factory outsourced supply!

Edit & Update - The link above does not work - the enitre thread was removed from the Meridian forum.

[Levi]

Hey Steven, interesting link.  They want tests results to backup your findings.  If it looks good in paper, does it means it sounds good?  Asked them if they can measure PRAT.

[StevenACNJ]

Wow got very crazy over at the Meridian Forum. I am not sure, but I think someone actually came out of the closet over this mod  

Good thing I didnt by the Meridian 861 Pre/Pro I was looking at. If I would have modded that supply, we would have people jumping from roof tops.  

They closed the thread which is good.

Cant thank Anthony enough for his terrific power supply. My Meridian G68 ADV is working perfectly and sounding wonderful.

[Occam]

Well, this is the Lab forum...... so lets get technical.
I believe the ps in the Meridian G68 is the UPO-653S-01 made by Universal Microelectronics -
http://www.umeu.de/
Its an open frame 3"x5"x1" 90-264VAC switcher producing
+ 5vdc @5A
+12vdc @2A
-12vdc @.5A
1%, 3% & 1% load regulation
50, 120, & 120mv p-p ripple
respectively.
The ripple figures are prior to any expected decoupling ( .1uf Hi K ceramic and 10uf electrolytic at minimum). Regardless, the specifications are not spectacular.
As to what constitutes 'sufficient' for a power supply in this application, that is a subjective and economic judgement....

So what options are practical?
1. Replace it with a linear supply, with 50/60hz, multiple secondary power transformer, high performance regulators and heat sinking, appropriate capacitance, etc... Good luck doing it in a 3"x5"x1" space (+ whatever 'unused' space is practically accessable)
2. Modify the existing swiching supply and/or replace with a higher spec switching supply of appropriate form factor.
3. Add additional circuitry, that will fit, either passive or active to kill ripple and noise. Passive approachs would typically be the addition of LC filtering. Most active techniques would necessitate the raising the 3 output voltages from the switcher by at least 1/2 volt for subsequent additional regulation. The downside of both passive filters and active non regulating techniques is minimizing whatever effects of the inherent increase is ps output impedance.

As to the filtered IEC inlet - I've never met a packaged EMI filter that couldn't be bettered by a larger power conditioner. Given a good enough replacement conditioner, leaving the original filter in circuit can be detremental. That was the conclusion from powering a Tact 2.0 via a Felicia diy conditioner.

FWIW,
Paul

[StevenACNJ]

Occam,

Not that I am interested in a linear power supply, Aberdeen supply is working out great, but there is plenty of room inside the G68 to install one.

While looking inside the chassis with the width going left to right, about 1/2 of the floor is unused. All of the modular boards are in the rear half.

When first looking inside, it looks odd to see the small factory power supply sitting there.

You wrote: "As to the filtered IEC inlet - I've never met a packaged EMI filter that couldn't be bettered by a larger power conditioner. Given a good enough replacement conditioner, leaving the original filter in circuit can be detremental. That was the conclusion from powering a Tact 2.0 via a Felicia diy conditioner."

Your findings were exactly the same as mine. Again I use a RS Haley for front end power conditioning and have a 20amp dedicated line. The first mod I did was simply to remove the IEC/switch/filter combo and replace it with a new IEC & seperate toggle switch. Used the original factory power supply (didnt have Anthony's supply at this time). Positive results were immediate & big.

[Occam]

Steven,

I was simply pointing out the options available (in the best of all possible worlds), in upgrading a switching supply. The is nothing inherent in switching supplies that automatically make them inappropriate for high end audio use. It is simply that the off the shelf switchers (chosen by manufacturers for small size, ease of regulatory compliace and economy) can certainly be improved. This is demonstrated by your own experience and that of many customers of Aberdeen. There is no practical, absolute best, but rather it depends on the specific implementation.

It interesting to note that Aberdeen is now offering internal powerconditioners as part of their mod options. Its far easier to implement a conditioner specific to the needs of a component, when the power draw and noise characteristics are known.

I spent last Sunday evaluating the NuForce P8 preamp. This pre, with its switching supply is a prime example of the need for proper conditioning, and its specific needs makes conditioning potentially straightforward. It draws a whopping 5watts (but 11va illustrating an abominable power factor) and with that draw, massive conditioning would be easy. Regardless of what the vendor says for marketing reasons, that preamp demands competent power conditioning, moreso than any linearly supplied preamps I've encountered.

[MauiMods]

Here was a post I was going to post before The thread was deleted from the Meridian Forum.

 
Mark,
 Yes, huge difference in the analog output,
at least for TacT and I think I can Safely say Meridian too. , the -12 and +12 is used for the opt-amp. And I know, you know, on a 3, output SMPS like the one used, the -12 and +12 is real CRUDE looking, compared to the 5 volt rail. On Tact the raw 5 volts from the SMPS gets split on the Motherboard with a LDO 3.3v regulator, then these two voltages Supply the digital sections. Given the above, the 3.3v parts has the lowest ripple spec. But the 5 volt rail beside powering the digital section, also powers the noisy Display. Then throw in the Noise from the ground planes, that the SMPS throws in, and you can we got one big mess.
 
And this is just from one component......
That will effect the "innocent" components down stream. Threw conductive interconnects, and from the common grounds in general.
 
Then Mix  in the digital signals  and clock oscillators, Ect... and what we got in ONE BIG MESS!.
You do not need any measurement gear to figure that out, or be tech inclined.
 
Mark, Pop you cover and use a lab linear, I am sure you have access too.
I can send you the plug, wired already to connect , to save you some trouble.
And we wont tell Meridian, what you tried.  ;c)
 
For a alternative drop in solution, Use a Condor GLC-65A.
It is the best I found. Unless someone can suggest a better one.

George the Moderator from other forum, wonders why his Bass not defined...  From the above statment above, you can be sure Jitter is his culprit.

Any comment?


All the best!
Anthony

[bebop86]

Hey- I the power supply the same my 861 ir would it benefit from Anthonys upgrade- Also is there someone in NJ that could perform the upgrade? gary

[MauiMods]

Hi Gary,
 what town you reside at?
I have a installer in the NY/NJ area.
The Power supply upgrade is sooooooo easy to install. I can walk you threw on the phone and be done in 5 min.

you just need to know how to turn a screw driver.

Anthony
Mauimods
Aberdeencomponents

[StevenACNJ]

Gary,

Are you saying that the power supply in your Meridian 861 is the same as in the G68?

If so you are in for a big treat by replacing it with one of Anthony's power supplies.

I also live in NJ and can help you with the installation.

As a starter, why dont you take some pics of the rear and inside your 861.

Post them here or email them to me and I can tell you exactly what needs to be done.