TWEETER POSITION

I am in the midst of upgrading the drivers on my IPL Acoustics S4TL kit loudspeakers. As I will need to make faceplates to attach the new drivers I have the opportunity to freely place the tweeters within reason. Given that I have been reading the magazine since 1995 this started tingling a few bells from the depths of the old DIY supplement with regard to the KLS9 speaker. The reasoning here was that it had handed tweeters – something I want to use to improve imaging.

So I went to have a look only to find that the distances and angles were defined but there was no information as to how they were reached.

So, the question is, how does one calculate tweeter-midbass distance and calculate degree of handing? The drivers are Volt B220.8 midbass, Morel ST1048 supreme tweeters and crossover frequency is 2.1kHz handled by the Steve Bench valve crossover: http://greygum.net/sbench/sbench101/#Electronic

The rest of the system has a definite Hi-Fi World influence: Nottingham Analogue Spacedeck with the heavy kit, Wave PSU and  tracer arm, Shure V15VxMR cartridge, Icon Audio PS3 phonostage, Bottlehead Extended Foreplay pre-amp with above mentioned crossovers, Oppo BDP-83 upgraded by Audiocom, Sony PS3, NAD T175 AV preamp 4, Icon Audio MB845 power amps, two IPL Acoustics S4TL speakers for stereo / front, two Rotel RB970BX power amps., four IPL Acoustics AVC1 speakers for surround Sharp 52” LCD.

Has anyone tried experimenting with acoustic panels covering such a large reflective surface right between the speakers when it isn’t in use i.e. playing records? I look forward to your response.

Keith Dunlop

Er, actually Keith - you don’t calculate it! The tweeter should, ideally, be less than half a wavelength at its crossover frequency with the midrange, or bass/midrange unit. Otherwise its sound will be more than 180 degrees out of phase at the crossover over frequency and a dip in response caused by phase cancellation will result. Since mids and bass/mids radiate high frequencies primarily from their dust cap, then the distance is measured from this point (if the driver uses a fixed phase plug, then from the plug edge). A wavelength at 3kHz, a common crossover frequency, is just 4.3in, or 109mm, so you will need to get the tweeter as close as possible (less than 55mm) to get within this rule of thumb.

The tweeter should sit flush with the baffle to avoid diffraction of the surface wave off discontinuities. This also means a smooth, flat baffle is best (and also a narrow one). Asymmetric positioning on the front baffle disperses left/right edge diffraction effects. World Audio Design loudspeakers like KLS9 also used quite large radius edges to reduce edge diffraction. All these little things improve image placement and stability; our listening tests showed such small attentions to detail add up to produce solid and stable images. NK

LOCAL WARMING

Can you advise me in my quest to enhance my current hi-fi system please? It looks like this:

The turntable comprises Michell GyroDec with Rega RB600 and Sumiko Blue Point Special cartridge. The phono stage is a Clear Audio Basic MM/MC

loudspeakers are Linn Ninkas and CD player a Linn Genki. The power amp is a Linn LK140 and preamp Linn Wakonda.

Interconnects and Mains Cables. Speaker Cables – QED XT400. Hi-Fi Table – Saturn 5.

I would like to upgrade in the following order: phono stage, loudspeakers then turntable, and the budget is £1,500, £5,000 and £4,000 respectively.

My initial feelings from what I’ve read are to look at the Icon Audio PS3 or stretch to the Whest PS.30R. The majority of the music I play is on vinyl and I would like a warmer sound than my current system is achieving.

I really have no idea at the moment regarding the speakers other than they cannot be much bigger than the Ninkas due to the shape and size of my room. Floorstanders appeal but I am happy to look at bookshelf if both the sound is great and they are visually appealing.

Finally the turntable. I do like the GyroDec and feel a natural urge to upgrade to the Orbe. An SME arm would add to this fine deck.

I appreciate that interconnects and mains cables make a difference so I could simply reduce cost on the source and upgrade these instead.

So can you advise on my current thinking please? The timescale for all my purchases will be within the next twelve months.

Dean Scholey.

A great small loudspeaker, the Audiosmile Kensai, now priced over £2k.

Hi Dean. The Icon Audio PS3 will certainly give you the warm, atmospheric sound you want and seems like it might be just what you are after. The Whest is highly detailed and analytical, but being solid-state inevitably drier and less romantic, shall we say.

For loudspeakers I strongly suggest you try Audiosmile Kensais, that seem to bring a smile to everyone’s face, irrespective of taste it would seem. That’s no mean feat. They are certainly one of the finest loudspeakers I have heard, by quite a long margin too, using a magnesium coned bass/midrange unit and planar ribbon tweeter. See my review in our June 09 issue. NK

Regarding phono stages, I’d not hesitate to go for the Icon Audio PS3; it’s brilliantly suited to your Linn electronics, inasmuch as it’s warm and your Linns aren’t; hence they balance sonically nicely. The Michell Orbe is a no-brainer - it’s a long way above the lovely and iconic GyroDec in sonic terms, bringing a far more stable, powerful and detailed sound; it’s very open reel-like, in fact. First of all though, upgrade your cartridge; the Sumiko is miles behind the capability of the rest of the system, so I’d be tempted to go for an Ortofon Cadenza Blue, ultimately to receive an SME IV or Audio Origami PU7 or Origin Live Encounter (on the Orbe, I’d go for the latter). Speakerwise, if it were me I’d be looking at Quad 2805 electrostatics, or Monitor Audio GS60s, depending on whether you want subtlety or swagger. DP

ALIVE AND KICKING

I have a budget up to £18,000 to spend on a new or second-hand pair of loudspeakers. Since 1991 I have had Linn Isobariks of various types and I now have the ultimate pair: the last made generation driven by an active system using Krell amplification. The sound is terrific, I enjoy all my listening hours and I always want to reach for another record, however, it is clear there is even better sound to be had so I have begun the quest for replacements.

I listen solely to LPs and my music is 60/70’s rock, Jimi Hendrix, King Crimson, Led Zepp, David Bowie, Joni Mitchell, etc.

My system consists of Cartridgeman Musicmaker Classic, SME 3012, Garrard 401, Slatedeck 2 layer plinth, Art Audio Vinyl One phono Stage with volume control so no preamp, Linn Activ Crossover, 2 Krell KSA-100s and 1 pair Krell KMA 100s and, finally, all of this drives a pair of Linn Isobariks.

I like a warm sound with lots of punch, essentially I want my music to sound like Rock music which means not clinical and probably not really neutral, which leads nicely into why I am writing.

So far I have heard four pairs of loudspeakers as alternatives to the Isobariks (three of them on home dem) and two are preferable to the Isobariks and two were very clean and neutral but not to my tastes at all. The leader at present, in the “race to replace”, are a pair of RRR FS-100s at a remarkable cost of £785 because I bought them ex-dem from a dealer in Holland. I have your review from November 2007 to thank for this marvellous discovery. Amazingly, the FS-100s are more to my taste than any of the three others, even though they range in price from £8,000 to £40,000.

My question is: what do you think I should audition? I am working with a superb dealer so I can get almost anything delivered to me for home testing and I would like to get your views on what I should request. My next demo is a pair of Usher Dancer Be-20s. My hi-fi room measures 16ft x 11ft x 8ft and it has brick walls with a carpeted suspended wood floor, it is superb for getting that “live at the Hammersmith Odeon” feeling.

Mike

From Latvia with Love - the big RRR FS100s have great bass.

The RRR FS100s really have great bass and are well balanced. We all loved them – and what a fantastic price! Those with long memories will remember Rigonda Radio of Russia and the big RRRs hail from the same plant, now in Latvia. I am glad you like them. There is little to match them for bass quality in rooms of limited size - and that is your problem. If your room was larger big Tannoys would suit and a Yorkminster would amaze, but it did not fulfill its potential in my lounge, similar to yours, compared to our 28ft square office listening room where it blew me away. You could try the smooth sounding DC8 or its gruntier cousin, the DC10. These are nicely finessed by Tannoy, but the DC8 does have a warm balance that not everyone will appreciate I suspect.

You will be very impressed with the Usher Be-20s, or the Dancer Be-10s. Perhaps a B&W803 Diamond might be worth auditioning too; I suspect the larger 802 or 800 will over energise your room. Auditioning this little lot will give your dealer something to do!

Sadly, for your room there are no magic solutions; it is difficult to get good bass and a punchy sound from a medium sized room. Don’t forget to have some generous foam filled sofas to damp it down; I use a three seat, a two seat, a single seat armchair and a foot stool – and this is only just enough to keep main modes under control, analysis shows. Rooms are difficult things to deal with!

Since you have money to spend don’t forget the XTZ room analyser that runs on a laptop PC. It is easy to use and will guide you to getting good results. Use wall hangings like rugs, or acoustic foam panels from Studiospares (www.studiospares.com) to damp down wall reflections. Then you should be able to get a clean, modern sound that will be great for Rock. NK

Usher Be10 is what you want, says David.

My thoughts run in the direction of the Usher Be-10s, with Icon Audio MB845s; I feel the 20s might be a little too big for your room, and set things off too much! The Ushers give a great 'rock' sound, all power and punch, gusto and guts. They're not warm though, but the Icon Audios are, and yet they're fast and physical enough (just) for high levels via the Ushers. This should be great combination. My only other course of action would be Martin Logan CLX, which are faster still than the Ushers, with even more detail and insight, but obviously less physical. DP