Been a while since my last posting, just to keep you updated on progress I've been listening to the 66's with the crossovers externally mounted tri-wired to the drivers and the original wiring which went to the terminals inside the cabs to the Leak TL12+ power amps. I've not touched the components on the actual crossovers yet, all original apart from taking out some of the HF (brown coated electrolytic cans) caps to bering the values closer to what they should be (6 and 4uf) These caps were the worst effected by age being way over tolerance eg. 1.5uf measuring 4uf!.
I've left the speakers so I could to get used to them since building new cabinets and to be honest because they sound so good. I have all the new components ready as per Ken's spec (Alcaps/Mundorf e-caps/Ansars for the HF and strapping the 72uf midrange by 5% - see previous postings)
I would have started surgery sooner had it been for the fact I had a bit of an enjoyable revelation when visiting Victor Angelo (of Terminator arm/Salvation TT fame) place a few weeks ago. He was using a digital front end using a custom media PC powered by a good DC linear power supply and an external DAC which was based on a Texas Instruments PCM5102 DAC (battery powered) and it sounded very good indeed playing CD redbook ripped recordings. So I've been on a mission for the past weeks to get a decent DAC and digital source. Vic has all his kit listed on his web site TransFi.
My Macbook Pro has a decent Cirrus logic DAC fitted and using Audirvana bit perfect output it has always sounded OK but nothing special driving a passive preamp to my efficient Leak TL12+'s power amps. I took the plunge and got a Chord Mojo DAC having read so many good things about their products. It's another league completely to the Macbook DAC way more musical and far more detailed but it's the presentation that wins me over. I read about PC's and laptops being noisey especially with switch mode power supplies etc. and the fact Vic was using a good LPS certainly proved their worth when listening.
So having read about the excellent dedicated audiophile software available tailored for the Pi - Moode/Rune/Volumio I wanted to try 'pure' battery power - no mains problems to worry about, and hear! What's the simplest solution......a very low power PC so I went for a raspberry Pi3 fitted with a Digi HAT spdif taking the digital signal direct from the I2s bus of the CPU (dedicated transformer and clocks with galvanic isolation). Hardwired the spdif from the PCB board bypassing the flimsy spdif connector then into a mini jack to the Chord Mojo. Powered the whole thing with a decent lithium-ion powerbank 5v battery and WOW!!! Once you've tweaked the configuration (I use Moode player) to everything highest possible quality you are in for a real treat, tracks become a real music feast - only having experienced on vinyl previously. I'm spending hours listening getting completely lost in time.....
I tried a R core transformer driven linear 5v power supply to the Pi, it sounds good, but doesn't have the cleanness of sound and there is a slight noise behind everything. Trying high current LiPo batteries, as used in drones and model cars etc. seems to give more dynamics - you have to use at least 7v 2.5a output with a variable voltage regulator to give the 5v required for the Pi.
Just thinking of a way to power the spdif board independently to see if that improves things further. You have to hear some of the high bitrate tracks 24/96+ and DSD - wonderful stuff.
Anyway, I've gone off topic, but am now ready to start changing crossover components to hear the improvements, with my new front end this should be easier to tell how things change. BTW elevating the 66's by a good 12 inches really helps clean up the bass and makes the cabinets even more transparent - even though it does make them look even more imposing - thank goodness I have my own room.......
Last edited by rodthebod; 24-04-2017 at 17:14.
Location: Glasgow
Posts: 109
I'm Richard.
I hope it's ok to post here to let folks know that I am currently undertaking a Ditton 66 refurbishment of my own. I have upload loads of measurements graphs etc that may be of use to others. If you fancy checking it out here's the link. Your contributions would be most welcome .
Main System: Mac Mini > Schiit Yggdrasil 2 OG > Yamaha A-S3000 > Celestion Ditton 66
Headphone System: Mac Mini > Schiit Yggdrasil 2 OG > Sparkos Aries / Schiit Mjolnir 2 > Sennheiser HD600
Location: Glasgow
Posts: 109
I'm Richard.
Has anyone tried the replacement HF2000 diaphragms being sold on eBay? (There are replacement MF500/MD500 diaphragms too). I'm wondering if these would iron out the ragged responses of some of the HF2000s I recently measured? I'd offer to be a guinea pig but I lack the fine motor skills required for a job like this.
Being a 66 owner for many years and having already renovated a pair, I SHOULD know the answer to this, but I've never been absolutely certain whether the 66 was designed around an HF2000 with 4 ohm or 8 ohm nominal impedance. Can someone please put me out of my misery on this? What would a 4 ohm and 8 ohm HF2000 normally read on a DVM? I am aware of the rule of thumb: Impedance = DCR + 15%, which would put a 4 ohm nominal HF2000 at around 3.5 ohms DCR and an 8 ohm nominal HF2000 at around 7.0 ohms DCR. Thus I'm struggling to see where my HF2000s that measure between 4 and 5 ohms DCR fit into the picture?
Also, at risk of revealing my distinct lack of EE knowledge, is it true that the HF2000 and MF500/MD500 are in wired in reverse polarity to each other? As the colour coding on the crossover wires matches the colour coding on the drivers terminals I just assumed all three drivers were connected in the same polarity?
Last edited by ToTo Man; 19-07-2018 at 14:35.
Main System: Mac Mini > Schiit Yggdrasil 2 OG > Yamaha A-S3000 > Celestion Ditton 66
Headphone System: Mac Mini > Schiit Yggdrasil 2 OG > Sparkos Aries / Schiit Mjolnir 2 > Sennheiser HD600
i bought when i had mine some supposedly rare red label hf2000 tweeters,when i recapped the crossovers i stuck them in and the top end was not as good as before,i checked my work on the crossovers and all was good,so i put the old tweeters back in and all the top end came back.
a call to falcon acoustics confirmed that the red label ones were from another speaker originally,i forget which but the guy did say they were 4ohm and not 8.
the reverse polarity is done at the crossover.so black wire still goes to the minus terminal etc.
My System
John Wood KT88 Amp.
Paradise Phono Stage
Sony TTS-8000 Turntable.
PMAT-1010 MK6 Tonearm.
Ortofon Cadenza Bronze
Sony X555ES Cd Player
Yamaha NS1000m Speakers
Location: Glasgow
Posts: 109
I'm Richard.
That's interesting. Way back on my very first pair of 66's I had to replace an HF2000 and I bought one with a DCR of 9.2 ohms and it was significantly quieter than the HF2000 in the other speaker which was around 4.5 ohms. I then bought an HF2000 that was 3.4 ohms DCR and it was louder than the 4.5 ohms DCR HF2000 in the other speaker. This seems to be the opposite of your experience.
Out of interest, what would be the effect of reversing the polarity on the HF2000? Would the output at the crossover frequency between the MD500/HF2000 be stronger or weaker? The measurements of the last pair of 66's I renovated show a peak in the response around 5.2kHz. I wonder how much this is to do with the HF2000's raw response and how much of it is to do with the crossover polarity.
Last edited by ToTo Man; 19-07-2018 at 17:10.
Main System: Mac Mini > Schiit Yggdrasil 2 OG > Yamaha A-S3000 > Celestion Ditton 66
Headphone System: Mac Mini > Schiit Yggdrasil 2 OG > Sparkos Aries / Schiit Mjolnir 2 > Sennheiser HD600
hi,
ive replied to you on the other thread
My System
John Wood KT88 Amp.
Paradise Phono Stage
Sony TTS-8000 Turntable.
PMAT-1010 MK6 Tonearm.
Ortofon Cadenza Bronze
Sony X555ES Cd Player
Yamaha NS1000m Speakers
Finally enjoying my Studio 66's now running in nicely after placing onto some DIY carbon Fibre supports, elevating these lovely things really gets the best out of the bass and using carbon supports makes the cabinets more invisible audibly. I'm so surprised overtime as I listen on how great they are for a 1970's speaker.
I tri-wired the recapped crossovers so I can bi-amp or tri-amp them. But just enjoying them with the Avondale Audio mono power amps and a valve driven Conrad Johnson (clone) preamp heavily modded, paper and oil output caps are devine. They are so efficient too sooo good on classical as well as Jazz and guitar rock. Happy man.
Goldring G99 with Hydraulic reference arm, Logic DM101 TT, Rega 250, litz modded, Raspberry Pi3, Justboom Digi HAT spdif into Chord Mojo DAC, Avondale modded Naim CD6. Amplification: Valve - Leak TL12+ pair, Passive pre home made, SolidState - RMS T65 monoblocks, Grad One preamp. Celestion Studio 66 monitors (restored) on carbon fibre stands, RMS Revelation 2's and Revelation 1's, Stands Unique Klarity. Stands Unique Carbon, TWS Wall supports, Avondale Audio black link cable.