New Posts New Posts RSS Feed - The Audio Science Review Forum
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Welcome to the Graham Slee Audio Products Owners Club

 

Open to all owners plus those contemplating the purchase of a Graham Slee audio product wishing to use our loaner program: join here
Subscribe to our newsletter here (Rules on posting can be found here)


The Audio Science Review Forum

 Post Reply Post Reply Page  <1 111213
Author
patientot View Drop Down
Senior Member
Senior Member


Joined: 28 Nov 2018
Location: USA
Status: Offline
Points: 609
Post Options Post Options   Thanks (0) Thanks(0)   Quote patientot Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan 2021 at 6:49pm
Originally posted by CageyH CageyH wrote:

So it is likely to be a completely unbiased review then?

Given that he made a measurement error, if it were my site (which it is not), I would take down any phono preamp review that's been done to date until things can be remeasured properly.

Leaving up bad info does no one any favors. I doubt this will happen though. 

IMHO, the site grew too quickly and he ended up with piles of equipment to measure. Rushing through it all, combined with his lack of familiarity with measuring phono preamps, means you end up with mistakes. 

That's my 2 cents on the situation. 

And yeah the peanut gallery there needs much better moderation. 
Reflex M + PSU-1 used with AT VM95ML, Stanton 680mkII + Ogura, and Shure M35X cartridges.
Back to Top
Fatmangolf View Drop Down
Admin Group
Admin Group
Avatar

Joined: 23 Dec 2009
Location: Middlesbrough
Status: Offline
Points: 5628
Post Options Post Options   Thanks (1) Thanks(1)   Quote Fatmangolf Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan 2021 at 8:36pm
From my own tinkering and taking lots of things apart I learned that not needing all the parts to put it back together doesn't make you cleverer than the manufacturer. A little knowledge can be a dangerous thing and I have certainly had that 'doh!' moment quite a few times.

Jon

Open mind and ears, whilst owning GSP Genera, Accession, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.
Back to Top
Godra View Drop Down
Senior Member
Senior Member
Avatar

Joined: 29 Apr 2016
Location: Mont-Royal
Status: Offline
Points: 106
Post Options Post Options   Thanks (0) Thanks(0)   Quote Godra Quote  Post ReplyReply Direct Link To This Post Posted: 13 Jan 2021 at 10:27pm
This kind of misinformation happen too often on audio related web site or on Youtube. The worst is nobody can't do anything about it. Before publishing something, people should double (triple!) check. They should also identify potential shortcoming (Hey! I'm not used to test these components :P). And finally, they should also think about the possible consequences of what they report. 
Clearaudio Performance DC with Clarify tonearm + Virtuoso V2, Tannoy Legacy Eaton, Accession MM and BAT VK300Xse
Back to Top
Graham Slee View Drop Down
Admin Group
Admin Group
Avatar
Telling it as it is

Joined: 11 Jan 2008
Location: South Yorkshire
Status: Offline
Points: 9919
Post Options Post Options   Thanks (2) Thanks(2)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 14 Jan 2021 at 12:11am
+0.5dB, is that all? I'm over the moon with that!

+0.5dB at 40Hz, it should be 17.8dB up, so that makes it 18.3dB up.

Add the gain of 62dB, and the gain at 40Hz should be 79.8dB, but it's 80.3dB. What's that in linear gain?

It should be 9,772.37221, but it's 10,351.42167.

( 10,351.42167 / 9,772.37221) - 1 = 0.059 or 6%. That's 6% out at a frequency where it's hardest to hear any difference at all. 6% out right next to the low-frequency extreme!

1dB is the quietest difference in sound level that can be reliably noticed and is usually tested at mid frequencies where the ear has sufficient sensitivity. 0.5dB at 40Hz will never be heard even in a double-blind test.

This is analogue circuitry, not digital. I'll repeat that linear gain; 10,351.42167. Cumulative error built up in a resistor-capacitor network. Was it same in both channels? He doesn't say. If identical, then I'm even more over the moon!

Does he call +0.5dB bass boost? The RIAA standard allows 2dB end to end. With the amplification required for MC, most knowledgeable users would be in hysterics by now.

OK, so he reckons that 0.5dB of error proves the inclusion of a rumble filter?

No, there is an input capacitor to block the bias current from polarising the cartridge. It has its own high pass turnover, which will always interact with any nearby filter pole. Below the 20Hz low end of the RIAA spec, the frequency response goes back down, but it doesn't attempt to remove rumble and warp frequencies. It will do a darned sight better than a DC-coupled input, which would continue gain where it is least wanted, and displace the cantilever.

If this was the analogue output of a digital player, then an 0.5dB error could be called sloppy because there is either unity signal gain or maybe 8dB at the most. Contrast that with the Reflex C circuit at 80dB gain, and that's bloody-good control!

We are assuming his inverse RIAA response is accurate. When we got our APX525, James Kelly told us they didn't do any RIAA presets. Maybe that's different now? If not, then the inverse RIAA has to be a third party. Still, I'll give him the benefit of the doubt.

But there is one glaring error I've not thrown in yet, and that's the -3dB loading on the AP's generator. Might be sufficient to result in the 0.5dB.

Either way, I'm happy, and I stand by my products' quality. Mr. Amir, you could have asked; I'm an easy-going decent sort of a guy. Instead, you decided you knew it all. Poor judgment?
Not simple enough for Google-Bot to understand...
Back to Top
patientot View Drop Down
Senior Member
Senior Member


Joined: 28 Nov 2018
Location: USA
Status: Offline
Points: 609
Post Options Post Options   Thanks (1) Thanks(1)   Quote patientot Quote  Post ReplyReply Direct Link To This Post Posted: 15 Jan 2021 at 1:56am
I know I would not be able to hear half a db of difference in the bass region. 

I figured he was dead wrong about the rumble filter. Thanks for explaining all this. 
Reflex M + PSU-1 used with AT VM95ML, Stanton 680mkII + Ogura, and Shure M35X cartridges.
Back to Top
 Post Reply Post Reply Page  <1 111213
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.01
Copyright ©2001-2018 Web Wiz Ltd.

This page was generated in 0.063 seconds.