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December 2011 Issue - page 4

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December 2011 Issue
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ONE FOR ALL CHANNELS?

I was just reading your review of the TX-NR 609 and found it really helpful, thank you for this. I’d like to ask one question but understand if you don’t answer as your websites no forum!


Its just that I’ve ordered this amp and wanted to buy some JBL Control One Pro speakers to go with it. They are, however, 4 ohms (whereas the JBL Control One speakers are 8 ohms). Following your tests, do you think it would be acceptable to use the One Pros or would I be better off buying the standard Ones? Do I risk the system overheating and is there something I should beware of?


Personally I would like to get the Pros and my girlfriend would prefer it too as she wants white speakers (the Ones don’t come in white). Yet if I risk damaging the amp then of course I want to avoid that.

Daniel

Cologne

 

 

onkyo-tx-nr609

Onkyo TX-NR609 will drive 4 Ohm loudspeakers with ease.


Hi Daniel, There is no problem using a 4 Ohm loudspeaker. All amplifiers can drive them nowadays and the Onkyo has plenty of reserve power, should you turn volume right up. NK

TUBE-TASTIC!

My time with the TRV-88SE valve amplifier has only improved as it’s run in and the whole system has become even more fun with the addition of a TRI CD4SE CD player. I had the opportunity, one long holiday weekend, to take home this player from my local hi-fi store and when it came time to take it back I missed it almost immediately, it was if something essential had been taken away. So, I bought said CD4SE two days later! It’s not an all-valve player, but has an Electro Harmonics EH6922 valve as a buffer in the output stage. Solid and well made at 8kg for it’s relatively compact size, the casework has the deep red colour of the rest of the range and the solid aluminium remote with red end caps is worthy of such a nice machine and is a delight to use, no cheap plastic here!


Well, I lived with the stock valve for some six weeks and thoroughly enjoyed the tuneful aliveness of it’s performance, it made me trawl through much of my collection, I danced, I sang, I listened and I found it worth every cent of the $2700NZD price tag.


Meanwhile, a musical buddy mentioned that he had a selection of various brand ECC88s that I might substitute for the EH6922 sometime, as I didn’t think I had anything in my own small collection to swap in the player. Funnily enough, I had a look through some valves I had removed from a little used MC phono pre-preamp and there were two rarely used Mullard ECC88s in perfect condition. Out came the EH valve and in went one of the Mullards. The first hour sounded somewhat dire, so I went out into the garden for a couple of hours and on returning to the lounge found an amazing transformation had occurred.

To say I was flabbergasted would barely describe how I felt, how can changing one valve make such a huge difference to sound of this player! I asked myself that a lot over the next weeks, often just shaking my head over the transformation with many discs. Just one valve! From the deepest bass to the most delicate high frequencies with triangles and gently brushed or struck cymbals at the back of the soundstage, the increase in transparency and fine tonal definition was astonishing to me. Not only had the soundstage increased in depth, but vocals projected forward from the mix, sometimes in front of the plane of my current KEF Q7 speakers and thereby separating the instruments on the soundstage, complete with their own cushion of ambient air.


Superbly recorded performances like Just Friends, from the LA4, are simply magic to hear, the ensemble alive in the room and every instrument focused and so intimately present. Being originally a direct to disc recording, even the CD layer of this sublime SACD is a joy. Bass has both better tonal definition and focused weight and I’m hearing small high frequency details that I’ve never noticed before. By comparison, the EH6922 is pleasantly warm, slightly less detailed, yet a little thickened in the spaces between instruments, while retaining the basic tuneful timing and communicative expression that is so effortless with this player.

In fact, it’s the way this player communicates the musical essence and emotional expression of a performance that really swayed me into realising it had quickly become an essential and integral part of the system. Something was missing without it. If you are able to secure a sample of this rather fun CD player, I’d be very interested to read of your impressions, considering your much vaster listening experience of the higher end CD players. For any future owners of a CD4SE, I can certainly recommend swapping out the stock EH6922 for another good brand.


Regarding my delightful TRV-88SE amplifier, it will soon be joined with a pair of brand new Triangle Antal EX speakers, shortly after I return to Australian shores in late August. I can hardly wait to hear this combo of TRI amp, CD player and Triangle speakers in my new home that’s waiting for me, especially after your experiences with amp and speakers, Noel!


Also, a set of new Shuguang Black Bottle KT88s will be on the way. I’m hoping the SlinkyLinks speaker cables I use will suit the more forward and slightly brighter Antals, otherwise I may have to look into replacing them with something a tad warmer, like the VdH Royal Jades or maybe something else you guys can recommend for me. I’d certainly appreciate any suggestions.


Once again, many thanks indeed for contributing to my musical joy! I would like to add my grateful thanks and appreciation to Paul and Andrew at Eastland Hi-Fi here in Gisborne, NZ for allowing me to bring home various items over long weekends, not only to give them feedback on the gear, but also time to listen in my own home to prospective additions to the system, the CD player and the excellent MusicStreamer II+DAC being the most recent.

Christopher White

New Zealand

OH AND...

I did mean to mention the fact that the TRI CD4SE player is the first and only player I’ve ever owned that I can just sit down and really listen to music with, no matter the genre. At this moment I’m listening to David Gray’s Lost Songs 95-98 and it’s utterly mesmerising. The only other CD player that has done that for me was quite a few years ago when a friend had a NAD Silver Line S1, it was connected to a valve preamp, upgraded Leak Stereo 12 monoblocs and Quad Electrostatics. From memory we were playing some female vocals in the form of Nancy Griffiths and it’s just as well I was sitting down, because I just melted and sank into the couch. No other CD player has done that for me until now. I’ll be happy if this is the last CD player I ever buy; sometimes I use my Apple laptop via Kimber USB cable to the MusicStreamer II+, through SlinkLinks ICs into the TRI amp and although there is yet another small increase in absolute purity and transparency in bass and high treble, I still prefer the emotionally communicative abilities of the TRI CD player, and whether some might say it’s added distortion of the valve or something else, I’m not bothered. Participating in the musical event is far more important to me than sitting there going, “Yes, the transparency is stunning and that extra cowbell in the back of the soundstage is more noticeable now ...... but .. I’m not moved.” The combination of the two TRI components is simply enchanting, made even more so by the addition of a Mullard 12AX7 in the front end of the TRI amp and the Mullard ECC88 in the CD player. Happyville!

 

 

 

triode-trv-88se

Triode Corporation TRI 88SE amplifier persuaded Christopher White to buy their CD45SE CD player.

 

 

 

PADDING OUT THE TREBLE

I am infatuated with loudspeakers! Big or small, I love them all! It never ceases to amaze me how those vibrating cones ‘n’ domes get as close as they do to reproducing the sound of an orchestra in all its complexity. Even an understanding of Fourier analysis and a knowledge that a complex waveform is simply the sum of its constituent sine waves, is insufficient to quell my sense of wonder!


But sadly, there is no such thing as the perfect loudspeaker. This fact is substantiated by Noel’s comprehensive loudspeaker tests, which frequently expose speakers that exhibit an elevated treble, resulting in an overly-bright balance.


Now, I notice that Editor David is happy to tweak the tweeter level controls on his reference Yamaha NS1000Ms in order to match the acoustics of his latest listening room. Surely what’s good enough for David is good enough for us mere mortals!


The incorporation of level controls, or L-pads, in loudspeaker design is currently out of fashion, but offers certain advantages. Unlike the treble control on an amplifier, which progressively rolls-off the higher frequencies, an L-pad in a loudspeaker circuit reduces the level of the tweeter across its entire operating range. This allows the user to reduce the overall tweeter level to match that of the bass/midrange driver.


An L-pad improves electrical matching since it maintains a constant impedance for the crossover network. It does so by simultaneously varying resistances in series and in parallel with the tweeter. Noel may be able to comment on the influence of L-pads on crossover design.

I suspect that the inclusion of L-pads may not be favoured by current loudspeaker manufacturers on grounds of cost. They may also be concerned that L-pads, if not adjusted properly, could reduce the desired show-room impact of the loudspeaker.


To pad or not to pad, that is the question! Perhaps the experts at World Towers can give a definitive answer.

Alan RJ Scott


circuit

Put an inductor in series with a loudspeaker to damp down treble suggests Noel.

 

 

graph-2

A series inductor rolls down treble by a few dB. Putting a resistor across it limits the amount of roll off, so high treble does not disappear altogether.

 

 

Hi Allan. You are absolutely right that a treble level control is much needed by many loudspeakers and adjusting tweeter output up or down (in practice - down!) would be very useful. I would like to see a Reference position commonly made available at least, where frequency response is set flat. This is best done using an L-Pad for the reasons you state, but just adding extra series resistance to the tweeter feed is usually acceptable. Loudspeakers like the Monitor Audio Platinum series need this badly, as they are great ‘speakers poorly balanced. A Reference position enhance their value I feel. It is best achieved by simple mechanical screw or plug system of the sort Tannoy use, situated on the rear connection plate. This arrangement is cheap and long lasting.


monitor-audio-pl300

 

 

Monitor Audio Platinum – a great loudspeaker that needs a Reference setting, thinks Noel.


But here’s an obvious way of curing screaming treble that any resourceful tweaker can try. Just put an inductor (coil) in series with one of the speaker leads (positive or negative, it makes no difference). A value of 0.05mH (millihenrys) will attenuate treble progressively. To limit the amount of attenuation at high frequencies put a resistor across the coil, 2 Ohms being a good starting point. These are only approximate values, because loudspeaker impedance will not necessarily be 8 Ohms, but they are a useful starting point for experiment. It is possible to buy cheap inductance meters these days and a 0.05mH coil or thereabouts is small and easy to wind by hand. You can get the bits at Maplins.


For students and engineers, the software I used to quickly illustrate this possibility is a free Spice stimulator, LT Spice, and you can find no end of amplifier circuits for it in the Yahoo based user group, including valve amps (whoo hoo hoo!). Just Google LTSpice. And don’t forget Audio Tools by Studio Six Digital, for the i-phone. For minimal cost you can turn your i-phone into a loudspeaker measuring instrument, to guide you when tweaking. It’s the only thing that makes me like my mobile phone! NK



 

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