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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June 2017

Cables
Dear Mark,
I had a good time reading you comments and views about the best wiring between system components.
May I dare to ask you if you had ever looked/listend at the "Connection" between an LINN Majik (3) and a pair of Graham/Chartwells LS 3/5? I've asked many "experts" (confined mainly high end dealers) opinion and did get double the amount of answers as to what might be most suitable. Now I would greatly appreciate your view. From someone who's approach seems so greatly grounded and intended to bring together two components with their most suitable connectors.

Would be great to "hear" your view.
Thanks in advance and Kind regards
Rainer - E-mail: rsrr13 (at) aol.com

MW
Dear Rainer,
Thank you for your kind words.
It is good to hear from readers who are doing thorough research before buying loudspeaker wire that might transpire to be completely unsuitable despite enthusiastic reviews. The reasons we often experience disappointment from a product universally praised by reviewers, are many.
Primarily, the problem is that there is usually only a small effect from a piece of wire between two components, regardless of the hyperbole expressed by reviewers whose wages are being paid by the advertisers in their pages.
Secondly, the effect of a length of wire between a source impedance and a terminating impedance is partly dependent on those two impedances and partly on the ability of the amplifier output stage to drive the combined cable and loudspeaker impedance.

The Chartwell LS 3/5a is a relatively benign impedance curve Falcon Acoustics can still supply spares. Chartwell were one of the original manufacturers supplying the BBC directly, while Rogers were more well known for retail sales of this little 2-way loudspeaker, originally conceived as a Grade II monitor for the BBC's own use for speech monitoring at outside broadcasts. Chartwell Electro Acoustics were set up by the Swisstone Group in 1976 to supply the LS 3/5 to the BBC and were eventually bought by Rogers. The LS3/5a has achieved cult status worldwide and it is notable that changing any single component part upsets its specification completely. That is the point of a monitor, to remain consistent.

The BBC LS3/5a designers would be horrified to think that the cable could affect the sound, even though they knew the bass-mid driver bolt material and tightness was audible. The designation change from LS3/5 to LS3/5a acknowledges one such group of production changes resulting in a modified crossover to match them. If yours is an LS 3/5, the impedance is nominally 15ohm with a FL6/23 crossover. The LS 3/5a is nearer 11ohm nominal and all Chartwell LS 3/5a made after 1977 should be like this.

The consequence of this is that your loudspeakers are an easy load for a modern amplifier. Avoid capacitive loudspeaker cables, because these will affect the frequency response of any loudspeaker. Any reasonable quality low resistance/low capacitance cable will do an admirable job. The longer the run between amplifier and loudspeaker, the lower the cable resistance per metre needs to be. Highly flexible, silicone insulated multi-strand cables will tend to sound warmer while ultra-stiff pvc insulated dumbell section cables will tend to sound more forward. Inexpensive pro-sector audio cables are usually a good starting point. Then try to build some of our TNT-audio DIY design cables to experiment. Just do not spend too much money, money is better spent on more music.
I hope this is helpful,
Happy Listening,
Mark Wheeler

TNT SandBlaster
Hi Lucio,
greetings to you. I have a question regarding the TNT SandBlaster: I understand about the container that can be made of anything and about filling it with riversand, but does the surface on top - that is lying on the sand - has to "float"? I mean, it must NOT touch the edges of the container and there should be a small gap all around? Is that the idea of isolation on top of the sand?
Another question comes to mind: when I touch my record player, I hear a low thumb sound. Can this be eliminated by, for example, www.autoschadeshop.nl/index.php/anti-dreunplaten?
Thanks for your articles,
Menno - E-mail: magknevel (at) yahoo.com

LC
Dear Menno,
yes, you have understood it well, the top shelf of our SandBlaster platform has to freely “float”, otherwise vibrations can pass through it (and reach the turntable chassis) via the outer cabinet. The noise you hear when touching your turntable highly depends on the kind of suspension (if any) it uses. In any case, it is quite normal that any noise that propagates through its structure is highly amplified by the cartridge! You can try with soft dampers between the turntable chassis and the shelf. This thumping noise can't be elimiated, though. Just avoid thumping the chassis of your turntable while it's playing :-)
Hope this helped somehow,
Lucio Cadeddu

Nelson audio image 65i manual
Good evening, please could you help me how to get a manual of the Nelson Audio Image 65i amplifier?
Thanks,
Simo - E-mail: simo.jaz6302 (at) gmail.com

LC
Dear Simo,
we don't have manuals so I'm publishing your request here in the hope some fellow audiophile can send you a copy of this manual. Nelson Audio seems to be out of business or, at least, the Company website is no longer available.
Hope this helped somehow,
Lucio Cadeddu

Active loudspeakers
Hi Mark
Just read your articles on active loudspeakers. Here is my question: is an active studio monitor like the JBL LSR308 or any other like active studio monitor the same as the active speaker systems you describe? If not what are the differences?
Thanks,
Dale - E-mail: dry509 (at) icloud.com

MW
Hi Dale,
Thanks for getting in touch. The JBL, like all modern JBL's professional monitor product range, is indeed a pukka active loudspeaker. Some companies making powered loudspeakers for iPhones, and other smart-phones, sell loudspeakers with inbuilt amplifiers that they describe as active even though there is only one full range driver per channel. The JBL LSR308 uses a frequency dividing network, or crossover, between pre-amp and power amps. Passive loudspeakers put the crossover between power amplifier and drive unit. As described in my articles the passive crossover position is the passive loudspeaker's Achille's Heel.
The JBL LSR308 uses a pair of 56 Watt Class-D amplifiers in each loudspeaker, one 56W for the woofer and another 56 watt power amplifier for the tweeter (which seems excessive but was probably cheaper to build this way). They're part of the '3 Series' featuring trickle-down technology from the higher priced 4 Series and 6 Series, offering a big bang per buck but with less accuracy and refinement, judging by the company's own specs and design goals. JBL are famous for shifting loads of air with minimal distortion. Low colouration is lower priority for them, hence these are very lightweight cabinets for such a big near-field monitor.
JBL have also improved phase accuracy in their recent models, so a big soundstage should be possible. With an active crossover and separate amplification for bass and treble, these should be capable of sweeping dynamics too.
I hope this answers your questions.
Happy Listening,
Mark Wheeler

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