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Thread: Renovation of Celestion 66 Studio Monitors

  1. #231
    Join Date: Jan 2013

    Location: Carlisle - UK

    Posts: 1,956
    I'm Ken.

    Default Update

    The Visaton Low Loss bi polar electrolytics arrived a few days back and I’ve been doing some comparisons for the 30uf Series cap using purley LL Lytics. (15+15uf)

    I have listened to and my order of preference is:

    1). Visaton

    2). Mundorf

    3). Alcap

    To me, the Visaton and Mundorf are better on all counts than the Alcaps, period.

    With my first and second choices the decision is less cut and dry and as with a lot of this type of comparison, my favourite changed from track to track, so it will depend on what voicing you prefer. I will try and describe the difference which is subtle and not dramatic:

    Compared to the Visaton, the Mundorf is a touch warmer/softer sounding, so gives good timber to acoustic guitar body for example. It’s not quite as crisp being a little less transparent, less dynamic with not quite the same punch. This makes trumpet sound less convincing for instance. Voices however are slightly smoother and less prone to highlight the resonance.

    Both these caps are good, I came down on the side of the Visaton for being more realistic with some instruments, it’s slightly more transparent, it just conveys a little more energy and emotion, but it is a small difference.

    Next is to try a mix of the Visaton and Polyprop............

  2. #232
    Join Date: Jan 2013

    Location: Carlisle - UK

    Posts: 1,956
    I'm Ken.

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    The parts have been fitted to the new boards and then located in the bottom chamber, behind the ABR unit.
    Burning everything in now before any critical listening.
    I ended up with a mixture for the 30uf series cap of about 7.5% Ansar Supersound PP & the remainder using a pair of Visaton LL electrolytics, so thats the bundle of three in the lower right corner.

    Got them ready in time for NEBO 5 bake off this Saturday - phew .

  3. #233
    Join Date: Jan 2009

    Location: Deleted

    Posts: 6,585
    I'm Deleted.

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    Really nice build - super work .
    Account Deleted

  4. #234
    Join Date: Mar 2012

    Location: Gloucestershire

    Posts: 3,377
    I'm Paul.

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    Neat work as ever Ken and light years in layout ahead of the factory crossovers (why they couldn't do them like this I'll never know). Must admit,I like the Mundorf 'lytics. A cut above some new production bipolar electrolytics. Must do some measurement comparisons to see if it can be traced as to why they sound a little smoother.

  5. #235
    Join Date: Jan 2013

    Location: Carlisle - UK

    Posts: 1,956
    I'm Ken.

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    Reffc - Hi Paul, you were right about the coils audibly interacting.

    I had the parts lashed up on the original boards, with the closer spacing. When I have moved to the bigger boards and wider spacing, without any other changes the sound is cleaner. It's early days and things have to settle in but that much is evident after only an hours playing time.

    I like the Mundorf Lytics and have tried the Visiton which I feel are slightly more transparent and dynamic, but I'm talking about very small difrences, they are both good and like you say the Mundorf is a bit smoother. Both these work well with 5 to 8% polyprop in the mix. 10% is too much, Ansar and ClarityCap ESA both worked well for me in this way, the small amount of PP brings a touch of refinement plus extra dynamics and welly depending where they are used of course. They just bring things to life without the problems associated with changing the whole Lytic for a PP.

  6. #236
    Join Date: Jan 2008

    Location: Wrexham, North Wales, UK

    Posts: 110,012
    I'm AudioAl'sArbiterForPISHANTO.

    Default

    Yep, fantastic stuff as usual, Ken. When you’re eventually ‘done’ with this project, and have optimised everything about the 66s to your exacting standards (and worked out a suitable cost), you’ll have a commission from me to do mine!

    Marco.
    Main System

    Turntable: Heavily-modified Technics SL-1210MK5G [Mike New bearing/ETP platter/Paul Hynes SR7 PSU & reg mods]. Funk Firm APM Achromat/Nagaoka GL-601 Crystal Record Weight/Isonoe feet & boots/Ortofon RS-212D/Denon DL-103GL in Denon PCL-300 headshell with Funk Firm Houdini/Kondo SL-115 pure-silver cartridge leads.

    Paul Hynes MC head amp/SR5 PSU. Also modded Lentek head amp/Denon AU-310 SUT.

    Other Cartridges: Nippon Columbia (NOS 1987) Denon DL-103. USA-made Shure SC35C with NOS stylus. Goldring G820 with NOS stylus. Shure M55E with NOS stylus.

    CD Player: Audiocom-modified Sony X-777ES/DAS-R1 DAC.

    Tape Deck: Tandberg TCD 310, fully restored and recalibrated as new, by RDE, plus upgraded with heads from the TCD-420a. Also with matching TM4 Norway microphones.

    Preamps: Heavily-modified Croft Charisma-X. LDR Stereo Coffee. Power Amps: Tube Distinctions Copper Amp fitted with Tungsol KT-150s. Quad 306.

    Cables & Sundries: Mark Grant HDX1 interconnects and digital coaxial cable, plus Mark Grant 6mm UP-LCOFC Van Damme speaker cable. MCRU 'Ultimate' mains leads. Lehmann clone headphone amp with vintage Koss PRO-4AAA headphones.

    Tube Distinctions digital noise filter. VPI HW16.5 record cleaning machine.

    Speakers: Tannoy 15MGs in Lockwood cabinets with modified crossovers. 1967 Celestion Ditton 15.


    Protect your HUMAN RIGHTS and REFUSE ANY *MANDATORY* VACCINE FOR COVID-19!

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  7. #237
    Join Date: Jan 2009

    Location: Deleted

    Posts: 6,585
    I'm Deleted.

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    Quote Originally Posted by Qwin View Post
    Reffc - Hi Paul, you were right about the coils audibly interacting.
    Umm... I did mention it way back in post #6 of this very thread.....

    I'm glad it has all worked out though .
    Account Deleted

  8. #238
    Join Date: Jan 2013

    Location: Carlisle - UK

    Posts: 1,956
    I'm Ken.

    Default

    Mark - Coil Spacing - Yes You were about the fifth to mention it to me and I was allways open to the possibility after reading the test results on Troels Gravesen's site a good while back. Trouble was no one seemed to have tried it and this mod meant throwing originality out the window, so I was a bit hesitant.

    It has cleaned up the sound, but only marginally, other things make as much or a bigger difference, internal wiring for instance. The early air core coils I have were wound quite loose, so that may also be effecting results, but renewing them would mean more expense with no guarantee of improvement. Having said that, one of the guys on diyaudio has replaced his early coils with the later ones wound on plastc bobbins and he recons there was a small improvement by doing this. All these things seem to be chipping away at the problem, but not really getting to the root of it.

    The speakers are sounding very good, but I'm still not completely happy, I genuinely belive the drivers are capable of better and it is the x-over design that is the weak link. Changing to the Seas Tweeter makes a slight improvement to the top end, but it's not really necessary as the original unit is very good, this was more about long term sustainability as build quality on the originals was not fantastic and finding good second hand replacements will get harder.

    Now I have a 6 channel Amp I may try going Active, or see if someone with a programable DSP will patch it in to my system for a try, just to see what kind of a difference that would make.

    I don't belive an active solution is a cure all but with this speaker set up it may work, the drivers are pretty well matched and the x-over circuit is very simple with no notch filters or zoble networks, not even an L-Pad used, so the active circuit would just be providing the high and low pass filters. An easily adjustable DSP would also allow some exsperimenting with x-over points.

    The bass crosses at 500Hz but this driver is also used in the ditton 25 and crosses at 2kHz in that application (if memory serves). Raising this a small amount would relieve the mid driver of some of it's low end duty where it is at it's limit. The Seas tweeter is flat way below the 5khz crossover point so again this could be reduced. I feel the 66 has a little too much emphasis on the mids and maybe tweeking the crossover points could give a more natural presentation. It would be trial and error and may not reep any benefits, but is up there to try. Once crossover points are established/confirmed a simple analogue opamp based active crossover could be constructed.

    It's a major step to take but this hobby is all about stepping up to the challenge, so why not.

    That's on the cards for after NEBO5.
    Last edited by Qwin; 07-01-2015 at 12:05.

  9. #239
    Join Date: Jan 2013

    Location: Birmingham

    Posts: 6,772
    I'm James.

    Default

    Quote Originally Posted by Qwin View Post
    Mark - Coil Spacing - Yes You were about the fifth to mention it to me and I was allways open to the possibility after reading the test results on Troels Gravesen's site a good while back. Trouble was no one seemed to have tried it and this mod meant throwing originality out the window, so I was a bit hesitant.

    It has cleaned up the sound, but only marginally, other things make as much or a bigger difference, internal wiring for instance. The early air core coils I have were wound quite loose, so that may also be effecting results, but renewing them would mean more expense with no guarantee of improvement. Having said that, one of the guys on diyaudio has replaced his early coils with the later ones wound on plastc bobbins and he recons there was a small improvement by doing this. All these things seem to be chipping away at the problem, but not really getting to the root of it.

    The speakers are sounding very good, but I'm still not completely happy, I genuinely belive the drivers are capable of better and it is the x-over design that is the weak link. Changing to the Seas Tweeter makes a slight improvement to the top end, but it's not really necessary as the original unit is very good, this was more about long term sustainability as build quality on the originals was not fantastic and finding good second hand replacements will get harder.

    Now I have a 6 channel Amp I may try going Active, or see if someone with a programable DSP will patch it in to my system for a try, just to see what kind of a difference that would make.

    I don't belive an active solution is a cure all but with this speaker set up it may work, the drivers are pretty well matched and the x-over circuit is very simple with no notch filters or zoble networks, not even an L-Pad used, so the active circuit would just be providing the high and low pass filters. An easily adjustable DSP would also allow some exsperimenting with x-over points.

    The bass crosses at 500Hz but this driver is also used in the ditton 25 and crosses at 2kHz in that application (if memory serves). Raising this a small amount would relieve the mid driver of some of it's low end duty where it is at it's limit. The Seas tweeter is flat way below the 5khz crossover point so again this could be reduced. I feel the 66 has a little too much emphasis on the mids and maybe tweeking the crossover points could give a more natural presentation. It would be trial and error and may not reep any benefits, but is up there to try. Once crossover points are established/confirmed a simple analogue opamp based active crossover could be constructed.

    It's a major step to take but this hobby is all about stepping up to the challenge, so why not.

    That's on the cards for after NEBO5.
    Hi Ken, Never heard the Celestion 66's so looking forward to hearing yours at NEBO5.
    Main system : VPI Scout 1.1 / JMW 9T / 2M Black / Croft 25R+ / Croft 7 / Heco Celan GT 702

    Second System : Goldring Lenco GL75 / AT95EX / Pioneer SX590 / Spendor SP2

  10. #240
    Join Date: Jan 2013

    Location: Carlisle - UK

    Posts: 1,956
    I'm Ken.

    Default

    Be nice to hook your Croft Pre up to them with my Power amp, will have to see if there is time to do that.

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