Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Turntable with G68, old ADC comp to new HW

Hi,

I'm wondering if someone here has compared the built in ADC in the old G-series (or 861.x) to newer ADC HW using SPDIF into the Meridian?

I just hooked up my old turntable with analogue input to the Meridian and it sounds fine, but can’t help wonder to wonder if there would be any audible improvement to to use a modern 24bit ADC and connect to Meridian via SPDIF.

Something should have improved over 15 years and HW today is pretty chep. I use external DAC’s via SPDIF out and that is an improvement to my ears.

Kind regards//
Rob

What’s the turntable / phono stage?

The key to good ADC performance is getting the gain(s) correct and using all of the available bits without clipping the input.

ATB

Steve

Hi Syles,

Understood, the more voltage the ADC can work with the better (without clipping). Given the same voltage from a good quality external RIAA amp would it be an audible improvement to do the ADC conversion outside the aging Meridian G68 using up to date HW?

Stay safe
//Rob

The G68 has "24-bit Sigma-Delta converter chips operating at upto 96 kHz on analogue inputs" and you can also set the input sensitivity from 0.7v to 2.8v in 3dB steps; so from a technical point of view the ADC is more than enough for most analogue sources (from memory, Meridian stated that vinyl sources are, at best, equivalent to 13-bits).

Do you have an ADC in mind, they aren't as prevalent as DACs; they seem to either be cheap little boxes or pro rack mount units?

To further answer your question, I don't think an additional ADC would bring much to the overall performance; the turntable, arm, cartridge, phono pre-amp and most importantly the condition of the actual vinyl are much more important.

All the best,

Steve

FWIW, I've been running my TT pre into a Meridian MPMax 221 which then sends SPDIF to a digi input on the G68. I've been doing this as the TT was across the room from the G68. The MPMax 221 samples at 24/96, and sounds pretty good to me.

I'll soon be moving back into our usual house, and I'll be going back to running straight into an analogue input on the G68, which also sounds pretty good to me!

Cheers,
Jason.

The Meridian G68 uses the Analog Devices AD1871 ADC chip which was designed in 2002. 20 years is a long time in the digital world and the newer ADAU7112 does have significantly better specs across the board. Not least the noise level.

I guess the question is if it is better to use an external HW ADC, feeding SPDIF into the Meridian and be subject to the Meridian sample rate converter of the same age, or to feed analogue direct to the Meridian via the 18 year old ADC chip and avoiding the Meridian sample rate converter?

I know that vinyl resolution is not all that great but with a good turntable & pickup and new high-quality vinyl’s there should be enough information to challenge the old ADC.

I’m using an MC pickup via a transformer to a modern external high-quality RIAA amp.

I was just interested if someone had tested challenging the aging Meridian chips and how they fair compared to newer technology.

Kind regards
//R

I doubt the source would challenge the ADC, I looked up the 13-bit thing I quoted up in the thread, it comes from the 518 manual:


It seems my memory was more forgiving of vinyl.

I no doubt that the modern ADCs will have better specifications than the old ones, but it's all about implementation , and Meridian did it well back then.
FWIW I can't find any piece of ADC/DAC equipment that has a S/N ratio over 126dB, which is equivalent to 21-bits, these limits are in the analogue stages.

The only way to be sure would be to listen to a new one against the in built one; did you have one in mind?

All the best,

Steve

PS I looked up the Meridian MPMax 221, 24-bit 96kHz ADC, 'S/N better than 100dB'; so real world performance is 17-bit (which is still more than enough for most analogue sources if the levels are good).

I use an SME 10 / SME IV / Ortofon Kontrapunkt b playing MoFi 45rpm vinyl into a G65 and compared to ripped CDs through Roon it sounds pretty good.

I don't think the ADC is limiting me and frankly I don't really want to think about whether it is. There are a lot of links in the chain.

Neil

I'm jealous, would you swap for a LP12, Ittok, DL110....

Hi

I had an LP12 many years ago (had to sell it pay school fees in bad times) being an engineer, and a bit of a perfectionist, I found I spent more time thinking it wasn't set up properly than enjoying it. The SME is foolproof.

Neil

The classic dealer FUD, you must get it set up regularly by an 'engineer' that's been blessed by the hand of Ivor...

I got mine when I was 16 (naive and believing the flat earth press), out of my apprentice wages, £200 with a Basik Plus arm, then I upgraded to the Ittok for £175 after a few years.
I gave up on the upgrade path, but I still have it; looking at the prices they go for on eBay, I should probably sell it and get a decent turntable, always liked Michell Engineering and SME.

All the best,

Steve

I'm curious, not having owned one (or ever been into vinyl in any serious way): Was the LP12 really any good? Or was it simply a just-about affordable mid-fi turntable? With lots of marketing hype and the clever upgradeability.