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What Pre/Power amp Are you Using to Drive Your KEFs?

 
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O'Shag
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Location: City of The Angels

PostPosted: Tue Apr 15, 2008 3:42 am    Post subject: What Pre/Power amp Are you Using to Drive Your KEFs? Reply with quote

I'd be interested to get a consensus of opinion about the pre/power amps members are using to drive their KEF speakers. I'm particularly interested in the 107, but also all other models.
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vistisen
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Joined: 01 Sep 2006
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Location: Denmark

PostPosted: Tue Apr 15, 2008 11:16 am    Post subject: Reply with quote

I have a pair of 107 original model speakers

I am using an Arcam FMJ A22 pre and P25 power amp. (The front end is also Arcam an FMJ CD23T)

I have both the kef KUB 107 and 200 models, I can not really hear the difference. I have (as can be seen on other threads here) an issue with uneven response, probably due to the previous owers reconing of the bass units with rubber surrounds. I have done a bit of research and come to the conclusion, that I'll try a DEQX unit to see if that can solve the problem. Just about to order it now. I update the relevant thread when I get some results, to be honest as it costs about 1500 , I'm not sure if i want it to solve the problem Confused

For my ears Arcam and Kef just go together. My room is about 100m3 and I live out in the country wih no close neighbours Twisted Evil . Even so I don't find it necessary to play too loudly, as the room seems to have a natural maximum volume, go above this and the music becomes a noise.
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Parts
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PostPosted: Tue Apr 15, 2008 11:26 am    Post subject: Reply with quote

Hello O''blocked word',

I myself have used a variety over the years (Classe, Musical Fidelity, Passe Labs, Linn, NAD, Pioneer, Technics etc), currently settled on Krell for the Kef R107. (Though my main system is not in situ at the moment)

Nothing extravagant either, just a Krell Kav-250.

Too be honest some of the bigger Krell's are a little too larger than life and maybe not quite as nimble/correct sounding? in the current location of my R107, which is rather compromised and at the smallest I would recommend with a 2m distance and me 3m (sometimes 2.5m) away with them firing across the room (large L shape), they are toe'd in, .5m away from the rear wall, right has more free space then left, left has a small corner near the back of it then a curtained window bay.
I have them set up on Mana Soundbases, with Felt rings around the treble and a diffracion strip on the outside edge of the midrange (ala NHT).
Could use a Bass Trap or two in the left of the room, in at least one of the corners, but overall the set-up and positioning is quite even and works well.

I also used a Musical Fidelity Nu-Vista 300, which like the FPB sounded a little larger than life, too much height and voices sounding like the performers heads were 4ft across LOL Very Happy (well not that bad).
I would have kept the Nu-Vista, but it did produce a slightly large presentation, though did sound sublime I didn't get on with a slight hiss/noise problem the Kef seemed to highlight, noticeable from 3m away. The wife thought they took up too much floor space.

I went from the Nu-Vista to the Krell Kav-250, (well I was going to buy a Krell FPB-200 but it had sold so I took the Kav for a demo), and was quite surprised at its power speed and transparency.
It uses a much simpler circuit and construction than the bigger amps, superb fast nimble bass down to the lower registers, but and this is where I think it clicks "in this location" the bass seems drier and slightly less weighty than the FPB and Nu-Vista, and of course the Kef are quite weighty and strong in the lower registers, which when coupled to a bass weighty bass performance amp, in a slightly less than ideal room, can over egg the puddin.

So I feel I got good synergy with this power amp (well good system synergy too), speaker, room combination. I get usefull output it seems down to 15hz and some at 10hz? System is still I find capable of highlighting diferences of resolution with various ancillaries, and most kit I find to perform as equally or better is usually a lot more expensive.
The Kav-250 is rated at 250w into 8ohms, 500w into 4ohm, but was measured at actual 300w 8ohm, 600w 4ohm, with good current delivery. It recieved very good reviews, I do think of it a one of those sleepers which performs above it's weight. Good match for the Kef R107 in price range and performance. (Oh and it's one of the quietest power amps I have used, nary a whisper when on and no music playing, even with 103db speakers you would be hard pressed to tell the power amp was on unless looking at it's LED)

I would maybe like to revisit larger power amps again in the future maybe, Bryston 14BSST, Krell bigger 600 or 700 models, a couple of others I would try, maybe?

I use a Krell pre amp, though previously used Audio Research, but in a quest for silent performance from pre-amps I moved to solid state (duh Rolling Eyes ).

I am still not 100% happy with my pre-amp choice, Tact and MF Audio would be nice to try, and I have had previous success with EAR valve pre, plus I find the Kube can be detrimental and a pain in setting up with certain Pre-power combinations.

For me I now feel room, speaker, power amp synergy can be very important, as finding power amps and speakers which worked in previous locations can be helped with a more sympathetic power amp choice in a new location can be a bit of an eye opener.
As tempting as the biggest baddest expensive power amp may be, it is worth demo'ing such items at home and keeping a cool head.

Definitely a solid state power preference with the Kef R107 though.

Kit I usually use, here not in use with Kef.


In order of shelf,

Gyro SE with QC power supply. SME IV tonearm with XLO Reference cable, usually an Ortofon Rohmann cart but this need sreplaced, and a Ringmat.

Theta Data III cd transport. (still superb and I find hard to beat, unless talking silly money)

Sonic Frontiers SF-1 valve phono stage.

Krell KRC-3 Pre amp.

Genesis Digital Lense (Jitter removal and re-clocking between transport and DAC).

Theta Pro Basic IIIa DAC.

Krell Kav-250 power amp.

The kit is sitting in a custom size Mana Rack, with the power on a Mana Reference Table, I had two of these Reference tables, but sold one, due to wife pressure about it sitting unused in a cuboard she used. (it used to have the Gyro residing on it until we had children)

Cable's there are a mix, with thin Atlas speaker cable driving Rogers speakers.
XLO reference from tonearm to phono.
Chord Chorus from Phono to Pre.
Chord Chorus AES from Transport to Lense
Chord Chorus AES from Lense to DAC.
Chord Anthem XLR from DAC to Pre.
Chord Anthem XLR from Pre to Power.

This is usualy subject to change, with Chord Signature speaker cable, Chord Chorus RCA for Kube, and Russ andrews Mains blocks and cables. Plus more Mana for a couple of other items not in that pic.

Steve
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O'Shag
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Joined: 28 Feb 2008
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Location: City of The Angels

PostPosted: Tue Apr 15, 2008 4:37 pm    Post subject: Reply with quote

Hello Vistisen,

I have heard much praise of Arcam electronics, but have yet to hear an Arcam component. In America Arcam is somewhat rare to find in audio showrooms. Do you find the Arcam to have ample power to drive the 107?

Your issue with un-even channel response is perturbing. I'm sure you've exhausted the possibilities of the imbalance occuring further up the chain, and determined the problem must reside in the speaker itself.

If I may offer an opinion, I don't think that using DEQ is the best way to solve the problem. Addressing the route cause is best. Have you contemplated a project to overhaul the 107 as a means to correct the problem and also service the components? If both woofers were re-done with the same rubber surrounds, then they should have much the same response I would think.
Given that the KUBE settings were tailored for each speaker, the internal settings may need to be re-adjusted to match the response curves of the recovered woofers. Have you checked all wiring to confirm the integrity of the connections? Its quite possible that oxidization has taken hold, or that there is a lose connection somewhere. John Atkinson has run into this before, and did not realize why he was experiencing problems in balance until he discovered the cause -a loose or oxidized wire.

Have you had the 107s apart to check things out? What have you done thus far, or have you not taken that step yet?
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Laemmle
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Joined: 11 Apr 2008
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PostPosted: Tue Apr 15, 2008 5:21 pm    Post subject: Made In Heaven Reply with quote

My KEF 107's are in heaven being driven by an Audio Research SP-15 (modded by George Kaye) pre-amp, which in turn sends it's 7volt output to the 'small' McIntosh MC-252 amp.

I have absolutely zero issues!

Admittedly it helps having a pro XLR KUBE re-worked by the aforementioned George Kaye.
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O'Shag
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PostPosted: Tue Apr 15, 2008 8:09 pm    Post subject: Reply with quote

My word Parts, that is an excellent system and you've taken care in assembling it. You've had some excellent kit over the years.

I think I would regard the Krell as somewhat extravagant. Laughing

I'm familiar with the KAV-250 as a friend of mine has one, but have never heard it with the 107. Excellent sound overall but I've observed that on occasion can sound a wee bit dry and cool with his Thiel speakers. It makes sense that it would be synergistic with the 107 though given the character of the speaker. I too have found that sometimes the smaller amp in a given line will sound better overall than its larger more powerful sibling. Thats why I sold my 'very important' Levinson No 20 monoblocks and kept my two 'not so important' No 27s, which I use in bi-amp mode when I can. They are conservatively rated at 100 watts cont. per ch. but to me sound better overall than my now departed No. 20s.

Your point about scale is a good one. The 107, especially with vinyl can through a big picture. The 109 is immense but not in an overblown way. If a speaker reproduces images bigger than life, there is always the danger of losing focus. Getting the balance between scale and focus is important. The only caution with good valve/hybrid amps is that tendency to be a tad too 'bloomy'. I admit that I'm partial to a 'bloomy' sort of a sound, as it does tend to add 'colour' and drama.

You could get really ambitious and extravagant and try the Krell Evolution series. Wink

Can you describe the sound of the following components which are intriguing to me; The SME IV, XLO phono interconnect, Theta Data transport, and Genesis Digital Lens. I've owned both the Sonic Frontiers SFD-1 Mk 2 and SFD-2 DAC. Both were good performers. But I sold the SFD-2 when I heard the Musical Fidelity Trivista DAC 21 - excellent. If Chris Johnson (ex of Sonic frontiers) upgrades the already excellent Trivista DAC 21, it puts it up there with the best DACs any sort of money can buy.

I have been looking at a new transport.

One more thing. Are you using a line conditioner of any sort?
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O'Shag
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Location: City of The Angels

PostPosted: Tue Apr 15, 2008 8:24 pm    Post subject: Reply with quote

Hi Laemmle,

thanks for the response. So George Kaye modified your SP-15 also? What changes did he make? Interesting that you chose a McIntosh amp rather than Audio Research. Did you prefer the sound? What does your cable arrangement look like? You need two additional balanced cables running through the Kube. Are you using the same cables for the Kube as for the rest of the chain?

By the way Laemmle, I did want to respond to you regarding Andrew Jones number. I do have his personal number. Hope you don't mind, but I feel reluctant to give it out without his permission. What would be best is if I got his office number in Torrance CA. that way you could leave him a message. I'll get that for you in the next day or so.
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Laemmle
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Joined: 11 Apr 2008
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PostPosted: Tue Apr 15, 2008 10:19 pm    Post subject: Reply with quote

O''blocked word'!

Just returned home from work.....early day....in before the other half so...on comes the system....listening to one of my fav's of which I never tire...Holst: Planets, a nice reading from the baton of Zubin Mata...this is realized via my Marantz SACD....what power!

George removed all the oem caps and replaced them with top of the line examples from MIT...a BIG BIG difference!

Actually the road to McIntosh was a long one. When I purchased my 107's in 1986 I had a Nakamichi CA7A pre and PA7 amp. This gave way to two Counterpoint SA220's, which gave way to a pair of Audio Research Classic 120's.........which gave way to Audio Research V-140's. Due to the hideous cost of replacement KT-90 'valves' I started to investigate my ss options.....which ran the gamout...ARC, Krell, Bryston, etc.

I purchased a mint used McIntosh MC7200 to get my feet wet as it were. I happened to love the utter synergy of the SP-15 with the 300 watt 'big mac'.

Convinced that McIntosh was in fact the sound I was at ease with, I purchased a brand new McIntosh MC-252.

I now have removed myself from the Audiophile merry-go-round of buy and sell. I now realize what McIntosh lovers the world over discovered....you hear MUSIC that does not tire and fatigue you.

As far as cables are concerned...all cables are Straight Wire Maestro.

Andrew's office phone would be fine....I will look forward to speaking with him after all these years!

BTW, hopefully 'parts' on this forum will post pictures of the pro KUBE I e-mailed to him.

107's singing so beautifully in the backround....think I'll end here and goose the gain pot on the 15 and push the KEF's a bit! After all the wife will not be home for 90 minutes!!!!

L
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Parts
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PostPosted: Tue Apr 15, 2008 10:27 pm    Post subject: Reply with quote

To quote Laemmle,
I'll end here and goose the gain pot on the 15 and push the KEF's a bit! After all the wife will not be home for 90 minutes!!!!

What a quote LOL, and I bet many of us know that feeling...

Picture's of Laemmle's system can be viewed in the Audio Equipment section.

Smile

Reagarding tube amps with the Kef R107, this is something I have never been comfortable with, nor which many reviews have found favor with in past years. Big Papworth's, Audio Inovations, big Jadis, Lumley mono's and Tube Technology mono's all seemed to be lacking due to the drive demands of the lower registers, lacking definition, slam, lacking mid bass punch and seeming detached with mid today bass tomorrow syndrome?

My own findings with solid state have also shown a need for drive and control, with various mid level high wattage models from Technics, Pioneer, Nad etc lacking control and bass definition, and not having mid bass punch and shutting down or clipping at high levels.

It does not have to be expensive though, Classe CA-100 and CA-101 can drive them well, with good bass definition and punch, though not quite plumbing subterranean depths like Krell and such. (will switch off at high levels of LF content though cutting off LF at 30hz with Kube helps)

I myself listen to a lot of fast percussive bass and LF content that many feel silly or "not" music though, ambient and alternative electronic and such. Quite testing of bass performance but not to everyone's taste.

Steve
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Parts
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PostPosted: Tue Apr 15, 2008 11:27 pm    Post subject: Reply with quote

O''blocked word' wrote:


Can you describe the sound of the following components which are intriguing to me; The SME IV, XLO phono interconnect, Theta Data transport, and Genesis Digital Lens. I've owned both the Sonic Frontiers SFD-1 Mk 2 and SFD-2 DAC. Both were good performers. But I sold the SFD-2 when I heard the Musical Fidelity Trivista DAC 21 - excellent. If Chris Johnson (ex of Sonic frontiers) upgrades the already excellent Trivista DAC 21, it puts it up there with the best DACs any sort of money can buy.

One more thing. Are you using a line conditioner of any sort?


The SME IV is described as many as sterile, neutral, with superb controlled bass, many find it too sterile and unemotional? Not me, I find it even in tonality and very detailed, consistent and controlled which I like (along with Ortofon characteristics and even Frequency response I guess many would akin it to a CD like stability?)
It is not as good as the Series V, which many say is slightly darker and more controlled, I think it compliments my taste well, neutral and suitable with a varied eclectic music collection. I had an SME 309 before this, and found the IV more fluid and detailed.

The supplied SME tonearm cable suppresses performance somewhat, a little lacklustre and uninvolving. The XLO reference (a little stiff and expensive I guess for the Gyro) opens up the treble and seems to let the music breath a bit more, bass seems more organic and natural with voicing a little more detailed. individuals seem more solid and palatable in the mix. Small and subtle but worthwhile improvements, I guess its all about letting more information through.

What can I say about the Theta Data III, it was one of those Absolute Sound and Stereophile top components during its lifespan, to me it is/was probably one of the best digital transports of it's time regardless of price, I thought better than the Theta Jade and Teac P-30. Superb analogue like performance with superb bass which I know sounds daft for a "transport", but it is quite over engineered and sounds sublime, easily noticeable when comparing with other transports for some reason? seems to lack that digital grain and has a really 3d organic quality. RRP was around 4500 without AT&T Glass optic option around 1995/96 if I remember correct? To my ears I think your looking at items like the DCS or Esoteric top models as replacements.

The Genesis Digital Lense removes jitter, Ram buffers the input and re-clocks before output, it removes sub code data and can add dither and change 16bit to 18bit. you get a delay with replay, and it well tell you original transport speed errors in part per billion etc. It is quite superb, and improves bass performance considerably, improves resolution and timbre, it actually gives more benefit in some of my cheaper lesser performing combinations, really hits the nail on the head with well mastered CD's.

You can still read reviews of this at Stereophile's web site. And Soundstage, and Hi Fi News all gave it good reviews. Good reading.

This is currently in use with an EAD Theatervision transport, which shows 0 PPM error, and was apparently comparable in performance to Mark Levinson's top model? I still prefer the Theta.

All (I feel) good kit, all recommended components of outstanding performance in their day it still sounds superb today, and I feel its performance is still up there with some of the best.
Good system synergy too, though I have been told Transparent Cables would add to the performance. It will do me for a number of years yet.
To be honest, if any of it failed or needed replaced I doubt I could afford modern equivalent replacements.

I am not using any line conditioners as such, I use Russ Andrews 8 socket pyramid block thingies with no filters, and have Tacima filtered mains blocks with I find slightly detrimental to overall quality with some of my kit.

PS Audio's newer Premier plant looks good, but cannot justify such cost at present.

Steve
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O'Shag
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PostPosted: Tue Apr 22, 2008 2:53 am    Post subject: Reply with quote

Great information Steve, thanks. I have been contemplating a transport. I do think a lot of the California Audio Labs Delta, which I'm currently using as the CD transport along with a Denon 3910 (direct w/no DAC) for SACD and DVDA. For CD and used in combination with my Trivista DAC 21, The presentation through the Delta as compared with the Denon, is more solid, aided by better bass performance. There is also a bit more clarity. I believe that I can improve things with a better transport, and that Theta Data looks very interesting indeed. I asked about the Genesis Lens because I've been giving serious consideration to one myself, although there are conflicting opinions as to its effectiveness with newer DACs.

Your comment on the SME IV and V tonearms are consistent with what I've read others say. Have you heard the Alphason HR100S? It is a throwback to the early 90s. It is very well-engineered and made of titanium. The SME V has been at top of mind as a replacement for me. The main contenders would be the Graham Phantom B44 or Triplanar - although both are outrageously expensive.

The Transparent Ultra cables, from my perspective, are exceptional in that they lower the noise floor, have clarity but with plenty of body and weight. Bass performance is excellent. The Supers are superb performers too. I used Supers before getting Ultras.
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O'Shag
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PostPosted: Tue Apr 22, 2008 3:17 am    Post subject: Reply with quote

If I may suggest a superb combination for the Reference 107, one that I've just tried and am surprised by the synergy. Using transparent cables going to and from the KUBE (MusicLink Super going in,MusicLink Plus going out - sorry can't afford Ultras for the KUBE too Laughing ) I decided to try a Class D amp to drive the 107. The Class D technology as you probably know is synonymous with excellent damping - ideal for maximum woofer control. The Class D amps, correct me if I'm wrong, also have the advantage of fewer components in the signal path given the switching Pulse Width Modulation topology which is highly efficient (80% of power is used to drive the speakers) compared to the norm, where much of the energy is converted to heat. I've observed that the better Class D amps have some common characteristics that are immediately noticable; speed/immediacy, clarity, transparency and excellent bass performance. You guys can probably see where this fits with the 107. The 107 is, IMO one of the ultimate speaker systems built. It speaks the truth, and sees much 'deeper' than a lot of other speakers do, even though some of the latest may sound a bit more flashy. I've had other speakers in my listeing room that sound more transparent, but miss inner details the 107 sees and reproduces clearly. The only area I would direct any type of criticism is an impression of a slight lack of upper treble energy / transparency with the KUBE in situ (a must).

The combination of the Class D amp works wonders with the 107. Why? That exceptional transparency, speed, and clarity that are inherent in the Class D technology mitigate that sense of a lack of upper frequency energy and transparency that are evident to me. Also, I'm convinced that the woofers on the 107 are a little difficult to drive if one is to get the best out of them. In my listening session last night it was immediately apparent that The digital amp exhibited absolutely superb control over the woofers.
If you can, please borrow and try a Class D amp on your 107s
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O'Shag
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PostPosted: Tue Apr 22, 2008 4:02 am    Post subject: Reply with quote

FYI, the Class D amp mentioned above can put out up to 1000watts!!
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