Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems Is this a valid test to see if my ears will hear benifits of Apodizing Upsample?

So before investing in a HD621 I tried to do some testing with what I have, to see if my aging ears could possibly hear the benifits.

I tried this on both 24/96 material from my Transporter and on a the PS3 playing a few SACD's and 1 24/96 Bluray.

What I simply did was toggle HS=Y vs HS=N (down sampling 24/96,88 to 24/48,44)

This would be HD621's "best case" in the other direction. Taking 24/48,44 and making it sound like 24/96,88 as best that it can, right?

Well I hear no difference when I "down sample" why would I hear a difference when I "up sample". I've read this debate numerous times that argue the difference between 24/48 and 24/96.

This is also consistent, I believe, with VK's notes from one of Meridian's talks that "16/44" should, in theory, be enough.

My understanding is the upsampler with apodizing makes it a "Better Upsampler" by removing preringing from the upsampling process. It does not removing prering in the original recording. Does it?

If the apodizer can remove preringing from orginal recording, then why must it always be part of an upsampler?

I do hear the benifits going from 16/44 to 24/44. But beyond that I hear nothing.

George, ignore the fact that it's upsampling as well as apodising at the same time. This difference is nothing like switching the current upsampling on and off. Nothing at all. You can't fail to hear this. It's not something you need to listen out for. It will slap you in the face.

Cheers

George

George,
Why would you invest in a HD621 just for the apodizing filter while Mr. Stuart has recently promised us (again) that we will get a firmware upgrade for the G68 with the apodizing filter?

Setting HS=N does not always shut "Upsampling Off".

It can also be used force something that is Natively Hi-Res down to Lo-Res. 96->48 or 88->44. That "difference" is about as large as you can get, isn't it?

It's a simple way to create this "difference" that the domain the upsampling/apodizer works in. That is, taking low-res and making it hi-res. I'm just going the opposite direction.

Now if we know for a fact the adpozing/upsampler does more than just a good job at upsampling and corrects for more errors than the upsampling introduces then my test is not valid.

Tired of reading the drueling over the HD621 and waiting.

Then there will be arguments over which is better, and better to do it earlier in the chain etc.

One thing people have not considered is will the G68/861V4 have 6 Channels of Apodizing or 2 Even if ever does come.

But I'd like to validate some claims and what my ears can hear.

I did not want to say it, but since you mention it, despite Mr. Stuart reassurance I am still a non-believer. Meridian has not even posted the V1.05 firmware for the HD621 on their site, although it seems already available for many months now. Seeing is believing ...

On topic: I do not believe you can test it with the equipment you have. M states it will remove pre-ringing caused by the 20kHz brickwall filter from the original recording, and your hi-def sources won't have that problem.

Thanks, so why does the apdozing filter have to be restricted to only being used in the upsampler.

I think the lack of HD621 firmware is an oversight or there is a reason they didn't want it public yet as they may still be working on it. I would not infer apodizing availability from that.

Me too. I'm planning a test like this at a dealer's store this Friday. I'm more interested in comparing CDs with and without the HD621 using the modded Oppo as a transport. Many have said that the HD621 cleans up the Oppo sound and I'm hoping I'll hear and like it. So I appreciate these comments -should help me quite a bit! JimK

We all agree, I am sure, that none of us should blindly go buy an HD621 without hearing the difference it makes first. A dealer test is the only way to decide if it is right for us (with our ears, our system, our room, our taste).

Using SACDs converted to 24/96 then downsampled has the disadvantage that you are starting with something which is only sort-of-hi-resolution (leaving aside the hype). The information above 20kHz on an SACD suffers from high distortion, and this technical weakness was discussed by Gerzon, and I believe referred to by Meridian when DVD-A was being first publicised. DVD-A has no such weakness (though it has other practical and licencing ones).

That is not to say that this invalidates your test, George, just that I would be a bit circumspect about starting with SACD in order to test something like this. The 24/96 Bluray you reference is a better start, but even better would be to cut out this approximate, though interesting, test, and borrow an HD621 from your dealer.

Any chance you can do that and report back? We'd all be interested to hear your findings.

I'm pretty confident you will. FWIW, I'm listening to the Oppo into the HD621 in preference to the D98 straight into the 68. I feel like the main reason at the moment for keeping my redundant Meridian spinner is as an analog video switcher and converter to HDMI for my aging Laserdisc player and my Freeview box.

Won't the brickwall filter in the 96->48 downsampling process also introduce pre-ringing, and so George's test is flawed?

A problem with testing for HD621 improvement is that the test has more than one variable. In addition to the HD621 as one variable you also have the interface as a second variable. The test with the HD621 requires the HDMI interface whereas the test without the HD621 requires the SPDIF.

Assuming the interface can be ruled out is a leap of faith. But this assumption is both reasonable and necessary to do the test.

Having said that, my experience is that you may not be able to notice the difference in a few minutes. But after listening to the HD621 all day then removing it, you will want the HD621 back in the loop.

To me, the most prevalent thing is better bass. Even aging ears should hear this. Second is less fatigue. I can listen at higher volumes all day long without the Joe's Garage scenario (mother screams "turn it down!").

Adding one more point: HD621 makes music sound more accuracte.