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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September 2006

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Real Stereo
Hi, just to let you know that I am an audio fan that likes stereo and vinyl records and that won't change ever. Therefore I also want to thank manufactors like Marantz that still support stereo these days.
Hopefully more will also invest in quality recordings so that today's youth can hear how real music sound like instead of listening to crappy mp3 sound.
Keep up the good work.
Best regards,
Tony - E-mail: tva_2 (at) hotmail.com

LC
Dear Tony,
thanks for supporting this noble art :-)
Young generations listen to MP3 because it's easy and inexpensive. We should tell them they can listen to their Music in a way that they can't imagine...without spending a fortune.
Buying second-hand (or building a kind of T-System) can be as expensive as buying a trendy MP3 player and a pair of decent earphones...
Thanks for the feedback!
Lucio Cadeddu

Ground noise
Hi, I've just bought a Garard zero 100 in good conditions.
The output wire termination is a DIN (3 pins). Inside the Garrard, the other side of the wire is RCA so I thougt I could just replace this wire with a regular two-sided RCA.
But then, I can hear the typical ground wire missing noise. Can I do a wire replacement like I did?
Must I had a ground wire from the inside of the Garrard to my amplfier to avoid the noise? Or should I plug back the original RCA/DIN wire instead?
Thank you very much for your advice and for the great job you did concerning your Garrard web pages.
Best regards,
Ambroise - E-mail: adv (at) tiscali.fr

LC
Dear Ambroise,
you can do both things: either run a ground wire from a metallic part of the chassis of the Garrard (try different locations) to the ground bolt of your amp or build a better RCA-DIN cable. Alternatively, you can ask FlashBack Sales to build (or sell) such a cable. They use good wires and are extremely customer-friendly (and definitely NOT expensive).
Hope this helped,
Lucio Cadeddu

Videophile on T-Amp
I read your article on the Sonic Impact T-Amp - integrated amplifier Can I use this to attach 2 speakers to my video ipod? Or better yet us 2 of them and push out more volume?
I would be greatful for your advice. We are adding a video ipod to kids toy car and need a battery operated way to push out power to speakers we want to add to the car. So I need help with best speakers to use as well..all on a working Dad's budget..
Any help will be forever in your debt..newby here not an audiophile.
Thanks,
Jordan - E-mail: jw (at) printmediany.com

LC
Dear Jordan,
considering the use, one single T-Amp would be more than enough. Choose car speakers of high sensitivity. They're all 4 ohm nominal (hence welcomed by the T-Amp) but sensitivity (measured with dB/w/m) is of paramount importance. My main concern would be battery life. Though the T-Amp is extremely efficient, batteries won't last much. Use rechargeable batteries if possible. Ot a 12V car or motorbike battery.
Hope this helped,
Lucio Cadeddu

Cartridge choice
Hi, I have a Thorens TD 125 with a Shure SME tone arm with a Stanton 681 EEE MK II. The power source is a Onkyo TX-8511 receiver, Electro Voice Sentry 100 A studio monitors.
Am I using an appropriate cartridge, assuming the stylus is in good shape?
Thanks,
Tom - E-mail: waterbowl (at) nycap.rr.com

DH
Hi Tom,
A nice system. I think your lowish mass arm and highly compliant cartridge are a good match (especially if the arm is the fixed headshell model--the SME 3009 Series 2 Improved). I have had good results with other similarly compliant carts (Shure V15 III and IV) on SME 3009 arms.
David Holgate

Hypex UcD amps
Hello Giorgio.
My name's Gabe and I live out in San Francisco, California and I just read your review of the UcD180 on tnt-audio.com. You know the "newbies, which are often young people with not so much money" you mention in your review, well that's me! I have a "sustainable rock & roll band" (www.shakeyorupeace.com) that tours on bicycle and uses all recycled products for our packaging etc. Now our challenge is to build a portable PA system that's:

So we can set up on the street, in parks, and in peoples barns and play live concerts in places where there's no electrical outlets. All of the Power-Amps I've picked up in my hands at the car stereo stores weigh about 25 pounds and it's been really depressing. The thought of bicycling hundreds of miles hauling that thing around made my legs already start to ache.
When I saw that the Hypex modules weighed so little my spirits lifted! I can't find any dealers here in San Francisco to ask questions from so that's why I'm here pestering you... I hope I'm not inconveniencing you.
My question is basically a "man eats the chicken which eats the worm which eats the leaf which eats..." question. I'm wondering what the next steps are after the guitar's instrument cable - what components I need to amplify that signal. I start with my
  1. guitar which has an...
  2. 1/4 inch instrument cable that sticks into...
  3. a mixer? that sends an RCA? signal to the
  4. Hypex UcD 180? that's powered by
  5. a 12 V battery? the "Power Supply Module"? and so it goes...
I basically don't know what I need after step # 2! If you can break it down for me I would be soooo grateful to you. Thanks in advance and feel free to download our songs if you're in the mood for some folk/pop music!
Peace,
Gabe - E-mail: gabesingh (at) gmail.com

GP
Hi Gabe,
the issue I can see is not the amp, but the power supply weight. UcD180 requires a dual power supply, that is requires +40V, ground and -40V connections. Clearly a normal battery is not directly usable (no way to get around it, even in theory the maximum audio power you can get from a single 12V power supply is 4W on 4ohm). If you just consider getting a 100 W tone from a UcD180 with a 4ohm speaker, you must supply +-30V supply voltages with an average current of 2.5A... this means that you need one of these two arrangements:

  1. a 12V battery and a DC/DC upconverter giving dual output voltages, and the battery will have to supply something like a 12-15A current, which is not low (I do not know how easy or even possible might be to find a DC/DC converter fitting our needs, but you could instead connect a 12V->110VAC switching converter with a 110VAC-> +-30/40V switching power supply, which should be both rather light, and possibly easier to find)
  2. 6 x 12V batteries connected in series, which sounds very much like a very heavy weight...
Just to give you some figures, in the first case a 12V 15Ah lead battery will last only 1 hour (!), in spite of a weight of 7kg. In the second case, it would last 5 hours, but you need some 42kg of batteries...
In practice, with a normal live program, a single battery could last probably a few hours, depending on the program and the level.
In theory you should be able to spare a lot of weight with NiMh batteries, but in the components catalogues I normally use I have not found any suitable, high current battery of this type. You could place 10 x 1.2V batteries in series to get 12V, but the internal resistance would probably be (too) high, and the current low.
The other pieces to connect a guitar and/or microphone to the amp might be a pre-amplifier and a mixer, but as far as I know this depends also on the pickup/instruments you are using. Please verify, I am unfortunately no instrument man....
I am really sorry I can't give you better news. In any case, please feel really free to ask me any further explanation /question.
Peace,
Giorgio Pozzoli

U-Byte cables
Lucio,
First-off, I'm no engineer so forgive me if my question seems simplistic or misses something that an EE or advanced amateur would consider part of their electrical ABC's.
I'm intrigued by the UBYTE speaker cables but don't understand why, if the coax is the superior transmission medium, is it terminated with what must be an inferior flexible lead-out? Actually what I should say is that I understand why the design calls for a flexible lead-out but could the design be altered to eliminate the need for the lead-outs and not suffer sonically? In other words, what if instead of building a single "bridged" cable out of two lengths of coax by soldering the center conductor of Coax A to the foil shield of Coax B, we simply soldered/cold welded the center conductor of Coax A to the foil shield of Coax A and the center conductor of Coax B to the foil shield of Coax B and used these together as our double coax, leaving enough center conductor exposed to connect directly to the power amp / speaker?
Eliminating the lead-out would seem to allow one to take full advantage of the superior transmission capability of the coax cable across virtually 100% of the cable length and, if cold-welded properly, eliminate the potentially signal-degrading solder joint at the center conductor of Coax A to the foil shield of Coax B junction as specified in the original design.
I guess what I'm asking for is a brief explanation of why it's necessary to bridge the two cables as depicted in the UBYTE schematic.
Thanks so much,
Dave - E-mail: dave.woodall (at) velocitus.net

LC
Dear Dave,
when dealing with speaker cables it's not a bad (or bizzarre) idea to "cross" the negative and the positive poles, even using two runs of the same cable. For example, you might have noticed that even the simpler TNT Star cable makes use of a kind of crossing technique. In any case, I might suggest two things:

Hope this helped somehow,
Lucio Cadeddu

T-Amp
Hi,
I'm a product design student at Brunel University. I've just read your fascinating review and reboxing guide for the Sonic Impact T-Amp and I'm really excited. I've got virtually no experience of Hi-Fi tweaking though so I wonder if you would mind me running some ideas past you.
I've got a fairly large room so I was wondering if it is possible to use multiple T-Amps and use them to increase the power output of the overall setup?
Would this be workable by just splitting the input signal from a single phono jack to the input terminals of each T-Amp and then combining the output signals for each speaker terminal from each amp?
Could I use just one pot for this setup or would each amp require it's own?
At the preliminary stages I'm just going to play with one T-Amp, but I don't have any speakers to go with. Are there speakers with the same price/performance ratio as the T-Amp out there? and if so do they work with the T-Amp?
If not what's my best avenue to pursue speaker wise if I'm after a setup to play movies and rock music primarily, but with enough versatility to enjoy a bit of jazz and classical as well?
Many thanks in advance for you time and suggestions.
Sincerely,
Peter - E-mail: ptt10k (at) gmail.com

LC
Dear Peter,
there are no speakers in the same price range of the T-Amp but you can still find something sensitive enough and not extremely expensive in the Klipsch catalogue. Have a look at the RB series, for example. For 150-200 bucks you can find something suitable to be used with your T-Amp. In order to use two T-Amps (for biamping) you need speakers with biwiring posts. Split the source output and connect one T-Amp per speaker (channel right for the bass posts and channel left for the highs posts, for example). Of course each T-Amp should receive a LEFT signal (resp. RIGHT) from the source. In any case, try one T-Amp connected to a pair of fairly sensitive speakers: you might find that 6 watts are enough most of the times (as many audiophiles have discovered thanks to the T-Amp).
Hope this helped somehow, keep me updated!
Lucio Cadeddu

No bass
Sir,
my system is as follows.

I have a dedicated room 13x20x9, with minimal acoustic treatment. I am unable to raise the volume knob even a few notchs, as the room gets filled with mid-high freq sound, with very little bass.
I am very dissapointed that though there are two 10 inch bass driver in each speaker, bass energy, force, impact, pressure are totally lacking.
What could be the cause of this unbalance, or is it a mismatch of amp-speakers?
Kindly suggest some good brand of speaker (FULL RANGE, 3 WAY) that will go well with my amp.
I am also thinking to buy a NAD power amp to drive the Klipsch.
Many thanks,
Arun - E-mail: enfieldarun (at) yahoo.com

LC
Dear Arun,
no new power amp or pair of speakers will solve your problem that, if I understand well from your description, is caused by a poor acoustic response of your room. First of all, try moving the speakers in different positions, that would help you finding the better compromise. Then add furniture and strategically place heavy curtains, carpets and pillows inside the room. There are many good websites devoted to room acoustics.
When all else fails, plan to buy a complete acoustic treatment for your room. It is money well spent.
Hope this helped,
Lucio Cadeddu

Loudspeaker tweaking
Dear Geoff,
Firstly, I'd like to congratulate you on producing this easy-to-follow guide to tweaking loudspeakers. I use a pair of inexpensive KEF Cresta 10s (I'd like to know your thoughts on these speakers) in my study (connected to a NAD 3020i). After the "run in" stage, they still sounded like bookshelf speakers, so, I thought I could see what I could do. After taking the speakers apart I could roughly figure out "what goes where" etc.
I decided to change the internal wiring I scrapped the generic bell wire and replaced it with some Atlas 3.0 cable I had spare. After putting the speakers back together I selected a Stacey Kent track to listen to them. WOW!!! It was though she was right in front of me the soundstage opened up and...WOW! I cannot believe the sound that these speakers are making. The bass is very deep, the mids are clear and relaxed and the trebles are clear cut and smooth. In fact, I prefer these to many of the expensive bookshelf speakers I've auditioned Epos, Dynaudio, Tannoy, Monitor Audio Bronze etc.
Once again, many thanks for your tips and tweaks,
Dan - E-mail: dbcarney (at) googlemail.com

GH
Hi Dan,
Congratulations, isn't it lovely when instead of handing over a wadge of cash to some manufacturer we can be satisfied with something we've done ourselves.
Keep tweaking,
P.S. Don't know the Cresta's personally.
Cheers,
Geoff Husband

NuForce REF9 amplifiers
Hi Lucio,
I've just bought a pair of NuForce Reference 9SE amplifiers (the red ones) and I totally agree with you.
They are running my Revel Studios (some very transparent speakers) with delicacy. No harsh sound at all, it's just liquid with plenty of details.
And yes, it requires some time to realize how magic they can be, but that's the way it is with high-end products. As far as I can tell, the most striking part is the harmonic richness. Pianos and sax are now being truly realistic. I think you'll find them more detailed and powerful than the original 9s, resulting in an even smoother sound.
Congratulations on your excellent site!
Guillaume - E-mail: gpbr (at) libertysurf.fr

LC
Dear Guillaume,
I'm about to receive a pair of REF9 SE's so expect a review of these babies pretty soon. I'm also waiting for other Class-D based amplifiers, in different price ranges...so stay tuned!
Thanks for the feedback,
Lucio Cadeddu

Edgar TP 105 tube amp review
Hello Lucio, thanks for your excellent review of the Edgar TP 105 tube-amp on TNT. I also own one and I completely agree with your opinion about it. I use it with Audio Physic Tempo II-SE speakers and this combination works perfectly. With my previous amp (Musical Fidelity E20 and E30) I didn't listen to CD's much because it gave me a headache.
With the Edgar this is no problem anymore but the performance with vinyl is also very good (with a decent phono-amp). A very fine amp, not the most detailed one but with a nice "Luxman from the seventies" analogue feel about it.
Greetings,
Dirk - E-mail: sloothaas (at) zonnet.nl

LC
Dear Dirk,
I'm glad you're enjoying this fine tube amp. Indeed it can deliver countless hours of pure musical pleasure. I hope it will get the success it clearly deserves.
Thanks for the feedback!
Lucio Cadeddu

Michell Orbe SE
Dear Geoff,
I'm one of the List-mates of the Italian Tnt-Audio Forum. First of all, Thank You very much indeed for Your huge work for audio-enthusiasts on Tnt-Audio together with Lucio; so, I need an info from You: I've read Your interesting article of 2001 upon the turntable Michell Orbe mk II with the ("new"?) VC power supply and CC motor...but the Italian distributor says that the new QC is better...is it possible?
What's your opinion?
Warmest Regards,
Paolo - E-mail: paulvanz (at) tele2.it

GH
Hi Paolo,
Motor supply upgrades do change sound but I'm not convinced they are as influencial as some say. Often such changes are done for other reasons, for example the Orbe went DC because Papst stopped making the AC motors Michell used. There was a difference is sound quality, but it was pretty minor. The new power supply is supposed to be better but I'd doubt it was a huge difference.
Incidentally if you are thinking of buying one do it now, as the current Orbe is in probably illegal as it uses lead in the chassis (as do several top turntables) and any replacement may well be inferior...
Cheers
Geoff Husband

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