SpeakerTalk

[O'Shag]

As I've mentioned before, I did not get the manual with the Maidstone. They are not like regular speakers in that many setup options exist. Therefore I am left wondering what is the best method.

I received these, and I was told that they had less that 30 hours on them. During the first several weeks I noticed dramatic changes in sound, especially the concentric/coincident source unit. At one point I heard what I percieved to be a colouration (distortion?) when producing 'ee' sounds like 'feels' 'been' etc. This has completely disappeared as far as I can tell. Also with respect to the MF/HF assembly, I felt over the first few weeks of listening, that the sound was a bit on the harsh side when raising the volume. The main center image presentation has transitioned from being a tad recessed to becoming more full developed (blooming?) if that makes any sense. I've never experienced this degree of change before - is it to be expected from these speakers?

The myriad of terminals and connection possiblities is daunting if one does not have direction, which I don't. Frankly, I don't even know if I have them wired correctly. Some guidance here would be greatly appreciated. I've thought about asking Andrew Jones but the Maidstone project was underway after he departed KEF so It would stand to reason his knowledge of this speaker is limited compared to others such as SpeakerGuru who have intimate knowledge of the speaker .

Given the Maidstone's unusual infinite baffle design, there is probably an optimal position with respect to the listener. Is toe-in suggested? My arrangement is such that my system is placed along the long wall, so the speakers fire across the shorter distance of the room.

I have listened at length to many top speaker systems. but have never owned one of this calibre myself. I did own the 207 a few years back but I knew from the first listen that this speaker is a very different kettle of fish.

Its been a learning experience so far. The level of transparency is startling - rather like a high-sensitivity design such as the JBL K2 or Everest, speaking of which, to me the Maidstone sounds awfully like a big horn/compression driver system in character with a similar sense of speed/immediacy, transparency, scale, and detail, although without the colourations and with better balance, much better bass performance and imaging imo. Such transparency means that any changes, even tiny ones that I make in the signal chain are clearly heard. The degree to which the sonic picture is painted with the speakers 'removing themselves' is also a revelation. Images are clearly defined, and dimensional. I stress this last part, becuase Ive never heard a speaker deliver the depth of the soundscape to such a degree.

I would like to get these very special speakers set up correctly, and feel I will not do full justice to them otherwise. Any help, advise or comments are most welcome.

[Parts]

Hello O''blocked word',

I have a link to a magazine review for you,

http://hifiplus.co.uk/t-rev3-6.html

Plus a design document,

http://66.102.9.104/search?q=cache:bexHMgvukuIJ:www.cobrason.com/include/pageredirect.asp%3Fid%3D159+Kef+Maidstone+R109&hl=en&ct=clnk&cd=3&gl=uk&client=firefox-a

This PDF should be readable, but I think it contained an error so may be incomplete or have some missing bits?

http://www.cobrason.com/data/fr/articles/r109pap.pdf

I have two or three magazines with rebiews, Hi-Fi Plus and Hi-Fi News, I am sure I have a US magazine too but could ne mistaken. I am sure Hi-Fi News discussed set up difficulties though.

The above articles may be of some use or provide interesting reading.

Regards,
Steve

[O'Shag]

Thanks Steve for that information. I've not seen that technical explanation before, although am familiar with the HiFi Plus Review. I enlisted the help of my son last night and we moved the speakers around a bit. Moving them forward towards the listening position and away from the front wall- where the TV sits - this in a addition to modest toe-in did yield gains in focus (although there is plenty when firing directly forward with no toe-in).

These speakers are a bit of a two edged sword I think, in that they are very transparent and revealing- not really the plonk-down-plug-in-and-live-happily-ever-after type.

Another observation - I don't think they sound quite right when bi-amping. I find I perfer the sound of a single amp. This is surely not right? It would make sense that these speakers will perform optimally when biamped. This is where I think I may be wiring them up incorrectly.

[speakerguru]

Thanks for the links Parts. I only had an early draft of the pdf with lots of marked up errors. Unfortunately, it doesn't help with connection details and I'm afraid that even though I laid out the crossover pcbs, I don't remember any of the details.

I think that the idea of all those terminals, was to allow the customer to either bi- or tri- amp with or without the internal passive filters. So, the most likely reason for things "not sounding right" is that the internal filter/eq has been inadvertently bypassed when connecting in bi-amp mode. Some of the terminals have shorting screws which enable proper switching. You can't bypass a crossover and still leave it connected across the driver, if you know what I mean.

Beware of bypassing the internal filters because they equalise as well as providing the XO function. Any active xo filters you might use instead will not have the correct eq.

[O'Shag]

Thanks for the input speakerguru.

Perhaps I could have said it better than 'not sounding right'. I hesitate to think there is any mistake in internal wiring. I perceive only a slight loss in energy compared to driving with a single amp (1000watt amp with which the R109 performs exceedingly well)although I would have thought this is the opposite effect than is intended? The question is not quite so straightforward though, as the electronics driving the speakers could be responsible - I don't yet know for certain, these speakers are transparent to whats going on upstream. Could the preamp run out of juice when driving two amps? I have not been able to verify this as my primary preamp wih two outputs is currently in need of servicing. The preamp I'm using at present only has one set of output jacks, so I use standard y-adapters on each side, then connect two cables per side to drive the amps. Do you feel this is a compromise and might have an adverse affect on performance?

Regarding the crossover design and connectivity; allowing the user to have such a range of options in driving the speaker is very useful and certainly sets the Maidstone apart from other high-end speakers - I can't think of any others that have such flexibility.

If I understand what your saying with respect to using external active crossovers, it is best to avoid this approach as the speaker's EQ settings will be bypassed? Does this apply when the external crossover is set with the exact same crossover frequencies as those designed into the speakers own network? The case for using external electronic crossovers seems to be convincing but I know has its own set of problems. I've never used this approach myself, but have watched friends of mine drive themselves up the wall trying to get their speakers to sound correct and fully coherent with the external crossover approach.

[speakerguru]

[O'Shag]

Thanks Speaker Guru.

I see your point and I will do as you suggest. Given that the design of the crossover has taken into account every aspect of driver control, equalization and output, it stands to reason that any off-the-shelf active electronic crossover will not be able to accomplish this properly. I will not pursue this as a solution to drive the speakers, but rather rely on the internal crossover network that has taken into account every facet of this speaker's performance.

My son and I listened to the Maidstone last night. He is familiar with my other speakers past and present, and others he has heard either at shows or at friend's houses. He is of the opinion that the Maidstone is way better than anything he has ever heard. I must say I agree with him. I do suspect that with the correct bi-amp setup, they will be even better. Are you by any chance Mr. Enrico Cecconi? Thanks again for you help.

[speakerguru]

In defence of active XO filters, they will result in a substantial increase in headroom if used in a multi-amped configurations before the power amps. This is because the high frequency peaks in the signal do not have to ride on top of the low frequency waveforms. The available voltage swing before clipping can easily double.

If Linkwitz-Riley filters are used then the outputs are -6dB at the crossover frequency and all in phase. There is no problem with cascading these active filters with the internal passive xo filters. The combination will result in the addition of an all-pass filter to the overall response. The amplitude response of all-pass filters is, by definition, "flat" and the additional phase shift of low order all-pass filters was found to be inaudible in double-blind listening tests carried out at KEF in the 70s and 80s.

Bottom line; don't bypass loudspeaker internal passive filters when using active crossovers.

Who was that masked man Why, that was the Lone Ranger

[proffski]

Tonto - "Kimasabe, is that you?"
_________________
I contend that for a nation to try to tax itself into prosperity is like a
man standing in a bucket and trying to lift himself up by the handle.
-Winston Churchill

[O'Shag]

Then, It would be possible to use an active crossover of the Linkwitz-Riley type, a long as the internal filters were not bypassed. I don't feel compelled to go this route at present given the sound I'm currently hearing, although I will likely give it a try at some point.

My first attempts at bi-amping were not completely successful, definitely down to incorrect setup.

Yesterday evening I put together a biamped setup - correctly this time using two Mark Levinson No. 27 amps (not especially powerful but wonderful sound), and had very different results. The single amp does an admirable job, and I did prefer it initially. Bi-amping these speakers takes performance to another level, eliminating any sense of compression, with increased low-frequency response/control. Another clearly audible effect was an increased sense of air - I don't know why this shoud be but it was very easy to hear. The sense of realism with decent material is quite breathtaking - I'm sure your very aware of this performance Speaker Guru as these are in large part, your creation. Do you own or have you owned a pair yourself? The bi-amped configuration definitely enables these speakers to deliver their full potential, and as such they will be biamped permanently from here on.

Always loved Gioachino Rossini's William Tell overture - Enrico who? Thanks again for your help.

[speakerguru]

The credit for the crossover design and therefore setting the balance on The Maidstone goes to Andrew Watson. Andrew spends countless hours above and beyond the call of duty, listening and measuring, on every speaker he works on. He is still currently working at KEF.