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

As you answered yourself Gizze

I didn't want this to turn into a Sky forum

I'm pretty sure that scaling from 576i to 1080i still needs de-interlacing to be performed in the Sky box. I keep reading that you can't scale interlaced video - only progressive. I've read proofs of this, and none of it stuck, but I think the result is terrible jaggies. Outputting 1080i from an SD broadcast would then require the following processes:

De-interlace 576i to 576p
Scale 576p to 1080p
Interlace 1080p to 1080i.

Yeuch, Nick

It's of little benefit as the only SkyHD box I know that can be forced by EDID is the Thomson box. Unfortunately it appears to produce 576i over HDMI and component by way of reinterlacing its own already deinteralced 576p. This causes PQ issues and using a high quality deinterlacing solution downstream is of little benefit in this case.

Avii

Er... power supply thread here, right?

I think there is a lot about the PS about the 861 performance over G's and 568. 568 had a linear PS (standard transformer) with 7xxx regulators, G units have a switched unit with some nice outboard caps and local regulation, and 861 has too a switched PS (not sure if the same as G, it is similar from the outside) but adds the big board with more filtering and a preregulation.

The case works here in 861's favour too (physical distribution, more space around PS and delicate signal components, and a less noisy display than Gs). To me 568 has the potential to be 'best' (I do like traditional linear PS...) but electronics are maybe not up to the newer units (no relays like on 861 for instance).

I must say for the level of power these units take there is plenty of space in 861 to make a truly nice linear PS, I never fully understood why switched (but there are who lke more good switched than linear, say Chord amps). No so much space on a 'G' I am affraid...

I believe that linear power supplies fitted to newly manufactured products have effectively been 'banned' as they waste too much power. This is presumably due to the standby power regulations requiring < 1W/2W standby power draw?

I`d love to try one of the improved Aberdeen Components power supplies in my G68, but what really appeals to me is a linear supply, even if I have to do some metalwork to fit a transformer in there. The amount of space available inside the G68 is comical - there`s enough for a power amp, never mind a pre-amp.

My Onkyo processor had three separate linear supplies, and that must have been worth it at a lower price point. I do have confidence in what Meridian do, but I`m sure there`s a lot to be gained with better supplies. I read a review of the 800 (or 861) by Martin Colloms where he commented on how well-behaved it`s switching PSU was. Yet IIRC, when he switched it on, he still measured 10dB degradation in SNR in the connected player.

Along the same lines, I`ve found that with HDMI receivers and processors, you get better sound if you disconnect ALL HDMI connections when you`re playing music only. Players and TVs usually have SMPS`s, and along with video, they create noise pollution that spreads through every power and signal connection in the system. More reasons to keep video away from the controller.

By the way, I also found that when A/B-ing players, you really need to disconnect the unused player to make a fair comparison. Otherwise both the active player and the pre-amp will be compromised by whatever electrical noise and pollution is being generated by the unused player. Switching between two active players is quick and easy, sure enough, but the better player may be degraded by the effects of the worse one.

So regardless of whether the processor`s own regulation and filtering is good enough for its internal requirements, a linear supply may still benefit the system by improving the sources.

Nick

Hi Nick,

I did'nt know there was so much space inside G68 too (861 is almost empty inside). The only G series gear I had my hands on, besides my own G08, was a G92 and it was crowded!

This is a nice shop with quite good service (IME) and here you have some options (reasonable non-ultra esoteric, but Meridian uses 7805s anyway): audiophonics

You do need +12, +5 and -12, and my bet will be to have the +5 better isolated as it powers the logic and digital components (and this is what Meridian does in the 861 PS with an extra pre-regulation in this rail).

So my 'first step' -or first try- on a G68/61 will be to add a linear regulated +5 supply and disconnect this line from the original PS (but let the original PS supply the +-12V analog lines).

Off course all at your own risk, etc etc

Not being particularly technical a lot of the above comments go way above my head but if I read them correctly it appears as though a linear power supply is to be preferred over switched. This being the case I am even more pleased with my recent purchase of a Logitech transporter as it has a linear power supply and it does sound good


Rod

I think linear power supplies are generally preferred on SQ grounds. Switch mode supplies, because of the necessarily high switching frequencies and harmonics, tend to generate lots of high frequency noise and interference that finds its way into everything, no matter how much screening and filtering you do. Linear supplies run at mains frequencies, which cause less noise. However, the transformers are less efficient, and therefore have to be much bigger.

I believe that switching supplies are used because they`re smaller, lighter, cheaper and cool-running, not because of any legislative requirements. SMPS are usually also auto-ranging, so you can use one supply in all markets. By contrast my Denon A1UDCI uses linear supplies, and that`s pretty recent.

Extending my reasoning before, I`ve been looking at the PSUs in other M gear. Apart from the odd G07, 506 or 561, all recent players and processors seem to have SMPS`s. I don`t think the power requirements are ever too great, and there seems to be space available in everything except the combined players/controllers/receivers.

Therefore there might be a case for an enthusiastic owner to upgrade the supply in their transport as well as the controller - or even in the HD621 as well. The HD621 might not do any analogue conversion, but it`s still a source of digital audio that`s vulnerable to noise and jitter. Not wanting to get too carried away, I bet a suitably compact linear supply would help both the HD621, and the rest of the system.

Nick

Meridian seems to only put linear where ever an analog Amp is needed.

I'm not sure I take everything M say at face value, but their approach to keep digital video away from whatever does the D to A conversion makes sense. Similarly it would make sense to keep SMPS away from DACs as well, and sure enough the DSP speakers use linear PSUs don't they?

That argument seems to fall down with controllers though. I think the 561 & 568 use linear supplies, but the rest are switch mode, and they perform D to A conversion.

There are many reasons that make me think linear supplies would be better with digital audio components as well, and this Why Meridian FIFO isn't perfect thread by VK is an example of one:
Extending the theme, PSU switching noise may corrupt the audio clock just like audio data corrupts it - perhaps even more.

Nick

Nick there is space inside your G68, I show you an example for sourcing some PS electronics (not expensive) and the original PS uses a common connector so it is very easy to put another one and test without cutting/soldering nothing... so... when do you come back with a report of the improvement heard (if any)?