TNT-Audio Readers' Corner
Monthly section devoted to your letters, positive and negative feedback about everything related to Audio and HiFi.

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November 2011

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Liquid music
Greetings from Adelaide, Australia.
While reading USB dac reviews Nov 2010 and April 2011, your writers included the software they use for the music - pc marriage.
I am very happy with dBpoweramp for ripping and QuuxPlayer with ASIO4ALL V2 for output.
All I need to arrange is that pc - hifi link and they are becoming cheaper each month...
HiFi is changing for the better.
Thank you for your help + good luck in the future,
Tony - E-mail: cmhabich (at) bigpond.com

LC
Dear Tony,
thanks for the feedback! We'll be devoting more and more articles and reviews to liquid music hardware and software as this is THE future, undoubtedly. We are also planning to write a simple (i.e. for dummies) guide to use a PC as HiFi source, in pure, plan and simple, TNT-style. Stay tuned for more!
Lucio Cadeddu

Re: Earthing + Spike
Hi Mark;
Thanks for the valuable input [see last week's letters].
I am near the sea, it can be very dry here but then it can also rain a lot too. I'm based in Cape Town. I will try and get a good reading of that copper rod that was written off today by my electrician and share them with you. Perhaps although the ground where it is buried is dry, this meter point 3 rod might just do the job.
Should I float the house earth and only connect the rod to the system's plug by ignoring the leakage setup of the house wiring?
This comment is in light of your views here "First, the spike or rod is additional to the original earth arrangement and so at DC the standard formula (summed reciprocals, to oversimplify) the combination is better than either." Isn't running both the original earth of the house to the hi-fi plug's earth and on top of that a spike connected to the same plug going to create an earth loop? Or am I misunderstanding you?
Thanks,
Ramsey - E-mail: ramsey (at) audiotweak.co.za

MW
Hi Ramsey,
DON'T DISCONNECT THE EXISTING HOUSE EARTH!
You probably have an earth residual current detector as part of your local regulation wiring that is essential for your safety.
I terms of earth loops, you can run as many earth connections as you like within the mains system because they are not either side of a gain block. The only problem arsies if you have an arrangement (as I have at times) of sources and pre-amps at one end of the room and crossovers and power amplifiers at the other end of the room. Even though I laid an ultra low impedance wide bandwidth connection under the floor by the shortest possible route between the sets of mains outlets at each end of the room, sometimes there are problems solved only by connecting everything to one outlet by a star arrangements.
Water the earth spikes before each listening session, or if you have a rainwater harvesting system (as i have - hence no added costly water consumption but Derbyshire is much wetter than Cape Town) set up a trickle irrigation system to your earth spikes. Mine are in the cellar next to a grey-water soakaway ensuring it is usually slightly damp.
I hope this is useful.
Mark, The Old Scribe

Class D amps
Hello Lucio,
I was looking for Hypex reviews because I want to include their modules in my PA peakers, so I found your article on the Genesis GR180 power amp. First, I was astonished by the price. 5000-10000 for this? I would really like to hear some blind test review between audiophile 5000 eur and PA 500 eur amplifier.
Anyway, I would just want to hear your opinion; is the sound of class D amplifiers comparable to ordinary AB class counterparts?
BTW, if you could hear the hum from toroidal transformers, they were really some low priced units, beacause generally, toroidals are better in every aspect than classic transformers. On the other hand, they are known to draw very high currents at the starts, and induce spikes of high voltage, so that's why they tripped your mains protection. For toroidals below 300VA it's enough to include a pair of 100nF condensers around the switch, for more powerful toroidals it is advisable to include soft start protection.
Best regards,
Mitja - E-mail: mitja.brglez (at) triera.net

LC
Dear Mitja,
if you read carefully that review you'll find my opinion about the price of the unit, definitely too high considering what's inside the hood.
My personal opinion on Class D amps is that the new generation of these sounds very well (NuForce, Hypex, BelCanto etc.), on a par with the best traditional Class AB amps, sometimes at a fraction of the price. I have no experience on Class D PA amps. If these use Hypex modules they can't be bad!
Happy listening!
Lucio Cadeddu

Earthing + Spike
Hi Mark,
I really enjoyed your 2008 review on earthing.
I'm not sure if you can still be reached via this email address, but I'll be happy if you could give me your input?
There is a lot of controversy surrounding a dedicated earth spike for one's dedicated high-end system.
Today I had an electrician try and install a spike outside my hi-fi room and straight into the ground, we were going to add two rods back to back to make it more than 3.6 meter long, however, we hit rock bottom when we literally hit a rock! He took measurements and although he couldn't go deeper than 1.3 meter, his measurements was "according to him" disappointing, so he snipped the remaining length of the first half rod and basically said to me, we'll have to try another spot next week.
These are the questions I wish to ask you, and would much appreciate if you took the time to reply?
Does measurements matter or should I just connect the hi-fi earth to that 1.3 meter rod anyway and see what benefits that has?
Is earth leakage now out of the equation an issue?
I was also told today that using an extruded 1mil sheet of aluminum or copper about 2 meter by 2 meter and even thicker could achieve the same outcome as a long spike?
What is your take on this?
Thanks,
Ramsey - E-mail: ramsey (at) audiotweak.co.za

MW
Hi Ramsey
If your electrician is happy that extra earths by rod or spike do not compromise the local earth regulations in South Africa, your system will benefit. I do not know whereabouts in South Africa you live, so I do not know the rainfall. Hence, what I say applies to temperate maritime climate Europe!
A reasonable 1+Metre copper (and you are near enough the copper belt to have good purity copper) earth rod in average moisture content soil (dirt) can have Z (impedance) as high as 2 or 3 ohms. The standard modern UK earth arrangement (where the earth/ground is coupled to the 'neutral' and carried by the outer sheath of the supply line where it inputs the property) earth Z (impedance) is tpically 0.3-0.5ohms. So you might imagine that there is no advantage to adding an extra earth.

However, 2 things alter the case.
First, the spike or rod is additional to the original earth arrangement and so at DC the standard formula (summed reciprocals, to oversimplify) the combination is better than either. Given that both will be frequency dependent according to the materials involved (including the mineral content of the ground - water itself is a poor conductor) the combination may well be more linear and lower the noise floor over a wider range of frequencies.
I am also aware of a trick, popular among the Flat Earth fraternity, of locating 3 earth spikes spaced in a triangle about 0.5M apart and linked as a compound arrangement apparently more than exceeding the sum of the parts. It improves with regular irrigation, I am told.
Aluminium sheet will be prone to eddy currents, which will have no effect according to some pundits but increase noise according to others. Try it and share the results with TNT-audio.com readers please. If enough people try things and describe the context of their experiments, we will soon have evidence. Then when a reader writes asking whether a 0.5x0.5M copper sheet is better than a 1M copper spike, in limestone (alkaline) soil in a low rainfall area, TNT-audio will be able to reply confidently, "our readers find in dry limestone areas X works better, while in ericacious (acid) clay soil Y works better".
Good luck experimenting and do please let us know!
Happy listening,
Mark Wheeler

Decware Z Stage
Hi Nick,
I am busy online at present looking to see what the direct companies are offering at present and I stumbled on this Decware Z Stage. It seems to be like a pre amp but more and can even be used with an existing pre amp.
Here is a link: - http://www.decware.com/newsite/ZSTAGEMANUAL.pdf. Perhaps you may have a look and see what you think.
Regards,
Mike - E-mail: mikebooth (at) talktalk.net

NW
I am fully in agreement with a stage before the power amp(s) upping the voltage/gain to improve dynamics. So I guess this would work OK. There are many other options of course!
Regards,
Nick Whetstone

TNT FleXy rack
Hi Mr. Lucio,
looking for a DIY rack I found TNT, started to read and to buy the necessary things. One thing I could not find even with excessive searching on the WEB are neoprene/gum washers for damping. Could you please give me a hint?
On the other hand I found something that might interest you, instead of the much more expensive graphite blocks: www.bfly-audio.de/p-serie-absorber.html. Perhaps you already know. When my rack will be ready and tested, I'll send you a feedback.
Best regards,
PS: Your DIY page is written in a very nice manner, I like it. TNT is very interesting, although many of the hifi components are a bit high-priced for me. Nice to read on your biography: Italia ("finalmente il buffone sparito" as a friend of mine wrote me), mathematics, fatherhood, Zen?
Gerhard - E-mail: gerhard.reuteler (at) aon.at

LC
Dear Gerhard,
thanks for your kind words of appreciation! Neoprene washers are easy to find at any bricolage/DIY store, they come in different diameters and thicknesses. I'd love to have your feedback (and pics) once the FleXy rack has been completed.
As for the price of the HiFi components we review: we always try to find a balance between inexpensive and state-of -the-art gear. I think that most of our reviews are of inexpensive gear, actually! See all those Class D amps, cheap USB DACs, affordable speakers...but we'll try to focus more and more on affordable gear, I promise!
As for the political situation in Italy, I'm afraid the change at the head of the government won't improve things significantly. It is the whole Italian political class to be obsolete...definitely vintage I'd say. We urgently need new heads. Sorry for the short off-topic!
Happy DIYing,
Lucio Cadeddu

Blu-tack
I enjoyed your article! But, there is a large after-market in products to control car panel resonances. See, for instance: www.caraudiodirect.esellerprostorefront.co.uk. IMHO, putting blobs of blu-tak (which ages unpleasantly) at random onto equipment is engineering-by-guesswork! I would prefer to take a more structured and systematic approach and use some of the car industry's products instead.
Cordially,
P.S.

  1. I have no connection with the car industry.
  2. Putting a blob of blu-tak on the nose of a cartridge is another example of engineering-by-guesswork. It will unpredictably change the resonant characteristics of the cartridge/arm and probably add resonance - rather than control it. I am not surprised that you heard what you hear.
  3. However, taking a very small piece of blu-tak, rolling it out as thinly as possible and putting it between the cartridge body and the head-shell can result in a better cartridge/head-shell interface. So, there is some rationale supporting this tweak!
Paul - E-mail: rutherfordpaul (at) yahoo.co.uk

LC
Dear Paul,
I know there are many automotive damping materials as we've used them in other tweaks/DIY designs, for example for our TNT Janus DIY turntable mat. This notwithstanding, blu-tack works fine, is extremely versatile, costs almost nothing and its application is always reversible. I don't agree with you that it ages unpleasantly. I've been using blu-tack for more than 20 years and it still works like it was new.
Finally, I love engineering-by-guesswork! It can be funny and makes you learn quickly by your trials and errors. Anyway, I've also suggested a more scientific approach using a stethoscope! :-)
Thanks for the feedback and happy tweaking,
Lucio Cadeddu

Havana DAC review / DEQ2496 question
Hi Nick,
with great interest I've read your review of the MHDT Lab Havana DAC, nice review by the way, and thought to contact you on a side question. It's about the squeezebox, DEQ2496 and DAC. It's the same setup I'm going to have (just ordered a DEQ2496 a few days ago).
But I'm not sure what's the best way to insert the DEQ. From the text I get the impression that you go SB -> DEQ -> DAC, is that correct? I assume you take the digital in/out of the DEQ? toslink?
Alternatively one could maybe take the route SB -> DAC -> DEQ, but that would be somewhat pointless imho, going D -> D/A -> A/D -> D/A. Would be nice if you could shed some light. Thank you!
Sebastian - E-mail: b-o-s-s (at) gmx.net

NW
Hi Sebastian,
I hope that my DEQ2496 guide on Decibel Dungeon will answer your questions. You are correct in that the DEQ goes between the SB3 digital output, and the DAC.
Regards,
Nick Whetstone

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