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The Quest for The KEF… Reference 107!

Discussion in 'British Audio' started by SimplySound, Apr 30, 2012.

  1. canuckaudiog

    canuckaudiog On a quest for high fidelity

    Messages:
    7,802
    Location:
    Edmonton, AB
    Yeah, that's right - the donuts are a dust cap, but also completely seal the cabinet off.
     

     

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  2. AVVA

    AVVA New Member

    Messages:
    3
    I just bought a used pair of 107s from an audio shop (they were a trade-in from another customer). No KUBE unfortunately so I need to find one separately. I was was told by the shop, and verified yesterday at home, that the woofers in one cabinet don't sound right and that in the other they don't work at all despite all being re-foamed. I started investigating the issues yesterday but didn't see any obvious visible issue and at least the bottom woofers do look like they've been re-done. I didn't have time yesterday to remove all the woofers to test them individually. I'll continue my investigation over the holidays but had one question right off the bat. How many foam blocks should there actually be in the upper and lower chambers? Should there be one on each of the 4 walls plus one cap on the bottom of the lower chamber and one cap at top for the upper chamber all with similar thickness?

    I'm asking because the left cabinet who's base sounded weak had two foam blocks at the bottom of the bottom chamber basically filling all of the free space with foam so I think that's what was over muffling the base. The dead right cabinet only had one foam cap on the bottom of the lower chamber which is probably the correct thing to have.
     
  3. SimplySound

    SimplySound Kent Engineering & Fondry

    Messages:
    2,495
    Location:
    Albuquerque, NM
    No there are two AVVA... take a look at this thread... never did finish writing this up!
     
  4. AVVA

    AVVA New Member

    Messages:
    3

    Thanks SimplySound, so I'm definitely missing the thicker foam block from my left speaker so I'll have to buy a replacement somewhere. I took them all apart last night and tested each woofer with a meter.

    Left speaker lower woofer - reads about 7.2 ohms with the meter and "works" when I hook it up directly to an amp but doesn't sound too great and doesn't put out much bass when the music has bass (although I have no other working woofer to compare it to -- see below )
    Left speaker upper woofer - ohm meter reads open - dead
    Right speaker upper woofer - ohm meter reads open - dead
    Right speaker lower woofer - was left disconnected by whoever went in there last but also the ohm meter reads open - dead

    One of the woofers that measured open has a visible break on the pigtails from the terminal so that's an obvious issue. The foam surrounds all looks good so I'm not sure what's going on...whether it was just a bad DIY or a bad shop that tried to re-do these...anyhow it looks like I need to fix all 4 of them and they probably need new voice coils. I'll call and get quotes from OC and another local place and then decide if I want to try to DIY or to send it in.
     
  5. k1creeker

    k1creeker Member

    Messages:
    79
    Please keep us posted on your woofer repair progress AVVA. While my set of woofers are working, I often wonder what would be the best course to take to have them repaired.
     
  6. SimplySound

    SimplySound Kent Engineering & Fondry

    Messages:
    2,495
    Location:
    Albuquerque, NM
    Sorry to hear about your woofers AVVA. Orange County is a great shop and has repaired 6 of my Bass Drivers. They can repair the voice coils on those so don't fret!
     

     

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  7. AVVA

    AVVA New Member

    Messages:
    3
    I sent the woofers out to get re-coned. In the meantime can someone please tell me how the cloth for the top covers is cut and attached to the cover frames? Mine only came with cloth on the back side. Some high-res photos all around a top cover might do the trick. The back piece is on and looks like it's just stand-alone. But for the front, top, left, and right side, I'm not sure if it's supposed to be one big piece with seams or if I'm supposed to use two pieces. Also it's not clear if it goes within the wood frame or over it.
     
  8. k1creeker

    k1creeker Member

    Messages:
    79
    AVVA, I've uploaded pics of one of my hoods below.
    The back piece is it's own fabric covered frame. The other 3 sides and top are one piece of fabric stretched over the wood frame and stapled to the inside. The only seams are where the back piece and main frame meet. Hopefully the photos help.
    https://picasaweb.google.com/111143...&authkey=Gv1sRgCOqRy9Xhu4vfRA&feat=directlink
     
  9. k1creeker

    k1creeker Member

    Messages:
    79
    It looks like you would want to remove the back frame, recover the main frame and reinstall the back frame afterwards. My back frame appears to be screwed on, I can't tell it it has also been glued in place at the factory. YMMV.
     
  10. steve59

    steve59 Active Member

    Messages:
    108
    Location:
    chicagoabouts
    My 107/2's are doing HT duty lately and these things are dynamic!!! try and fall asleep to your favorite series on netflix forget about it. I have some revel f-52's in my main music room (basement) right now and they're modern, revealing and full range but I think they are more sensitive to electronics because while they're like wearing headphones they're so tight they sound a bit sterile compared to kef's. I have to say I never got to hear them thru the same amp as my kef's so i'll have to lug nearly 400 lbs of speakers up and down stairs to do a fair side by side.
     
  11. k1creeker

    k1creeker Member

    Messages:
    79
    Hi all,
    I'm wondering if you other 107 owners can share your thoughts on your amplifier pairings with the 107. I'm currently powering mine with a Conrad-Johnson mf-2250 which I had originally acquired for my last speaker pair ( Gemme Audio Tanto v2). The cj is a great amp, and was fantastic for driving the Tantos, but I'm beginning to feel its merely adequate for the 107. I can't say its a wattage issue since most of (90%) of my listening is at moderate to lower levels. The cj puts out about 180-200 watts into 4ohms (cj doesn't post 4ohn figures).

    I feel there is room to tighten up the bass in the 107s and a little more clarity up top ( given the T-33 limitations).
    Just wondering if anyone has been on the amp merry-go-round with this speaker, and found one that was what they feel a perfect fit.

    Thanks!
     

     

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  12. Raynald

    Raynald Addicted Member

    Messages:
    5,139
    Location:
    Montreal
    Perfect fit? From my days working with them I would say Mark Levinson 23.5. The big Perreaux PMF 3150/3350 did well also. Mine just cruise as background for now on a Yamaha RX-V1 so I will let others chime in with easier to find recommendations.
     
  13. SimplySound

    SimplySound Kent Engineering & Fondry

    Messages:
    2,495
    Location:
    Albuquerque, NM
    I've been enjoying my McCormack DNA-1 pushing them. I just purchased a Classe Fifteen and will have a listen on that. Not much other experience from me.
     
  14. SaSi

    SaSi Seriously Illogical Subscriber

    Messages:
    4,179
    Location:
    Athens, Greece
    The R107 are an easy resistive 4 ohm load (they don't have impedance dips) so they don't overload the amplifiers. They need ample power and it's easy to overdrive the amplifier into clipping with them, especially if it's low powered.

    For listening at moderate levels in a medium/small room, a 2x100~2x140W @4Ohm amplifier is pretty good. To get their full dynamic range potential, you need twice as that on the amplifier. And because they are 4Ohm loads, most amplifiers can't be bridged to drive them.

    I have tested them with a Technics SU-V10x amp, an SU-V6 (both good results) and currently driving them from an SE-9060 that gives a measly 110W/4Ohm.
     
  15. rx7rotary

    rx7rotary Active Member

    Messages:
    483
    Location:
    Auckland, New Zealand
    Hello Sasi, how are you?
    I am running the r107 with my Audio Research Classic 60 without clipping and rather loud, with a 4 ohm tap. Seems to be fine at the moment without too much stress on the amp. In future I plan to have a dedicated bass amplifier once I am ready to set the 107 for bi-wiring.
    m
     
  16. Raynald

    Raynald Addicted Member

    Messages:
    5,139
    Location:
    Montreal
    As Sasi stated, the 107 are not that bad a load. Fairly efficient and just resistive so any good quality amp that was happy with a 4 Ohm load would do the job. We would impress people by getting good sound out of them with little Cyrus and Audiolab integrated amps, though as I said earlier they responded well to the best amplification.

    What you need is something with good current reserves, particularly when using the Kube. The low bass boost was like having the bass turned up or the loudness on. Combined with the 4 Ohm load and the ability to play loud you could quickly get a low current amp in trouble. The 107 were not as bad as the little 102 in that regard as the smaller speaker seemed to use much more bass boost with its Kube. Amps with touchy protection circuits would shut down on big bass passages and ones with poor damping would bottom out the woofers.
     

     

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  17. k1creeker

    k1creeker Member

    Messages:
    79
    Thanks for the input on amplifiers guys! I was seduced by the glowing reviews I read on the (now vintage) Jeff Rowland Model 2, and pulled the trigger on one over the weekend. It will output 2x150 watts into a 4Ohm load, and supplies 20 amps continuous, and 35 amps of peak output current. The quality vs quantity approach in their earlier designs appeals to me. I'll report back on the synergy when I get it in the system. Cheers!
     
  18. frommerstop

    frommerstop Super Member

    Messages:
    2,549
    Location:
    Detroit
    I suspect that Rowland will be a great match! As others have said, the 107s are pretty happy with most good stable (into 4ohm) amps, personally I've had very good luck with tube amps down to 60wpc, like Dynaco/VanAlstine IIIs, but they seem to like a bit more from a SS amp. IME, Luxman B-12s (80wpc monoblocks), or a Spectral DMA50 sound very good, but are not quite as dynamic as one might like, a bit more power, like a Krell KST100 and they start to really shine... currently, I'm using a Briston 4Bst, and I'm VERY happy with that pairing.
     
    Last edited: Feb 29, 2016
  19. k1creeker

    k1creeker Member

    Messages:
    79
    I had the Rowland amp in my system a grand total of two days. Unfortunately, it arrived with a couple of problems. One xlr input plate had loose connections and the plug had to be positioned in one specific way to get a signal to work, the other issue was a white noise hiss and some speaker popping in one channel upon power up. This diminished as the amp warmed up. But sometimes, the whole system would be off and I could hear the right speaker hissing at random intervals.

    I had a few hours of critical listening before packing it back up and sending it back for repair (I'm hopeful it can be repaired). The model 2 did wonders in adding a sense of air in higher frequencies and greatly diminished the slight grain I was hearing from the t-33 with the conrad johnson amp. It was able to drive the 107s plenty loud for my needs without distortion or clipping, but again, I'm not a concert level listener. I'm also not a professional reviewer, so the best way I can describe the model 2 is smooth and airy. The higher frequencies have a more delicate sound than with any other amp I've used. Surprisingly, the bass provided was deeper and tighter than the CJ. I had to turn down kube settings to prevent bass from overloading the room.

    It may be a while before I see that amp back in my system, but I am definitely looking forward to its return. Thanks to all for sharing your amp pairings.
     
  20. dave101260

    dave101260 Its all about listening

    Messages:
    71
    Location:
    Braintree, MA
    I just found the same thing on mine, and I've had my 107's for over 5 yrs.......What were these idiots thinking??
    I'm a little pissed off.......just a little!!
     

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