SonicArt Posted February 27, 2023 Posted February 27, 2023 Having been involved with Oracle Audio for a very long time now, I thought it would be helpful to create a thread which shows some of the various tables I have restored, upgraded and repaired over the years. I do a lot of custom fabrication when needed, and can manufacture many upgrade parts for Oracles from the original Mark 1 on wards. If you have an older Oracle TT and haven't done much/anything to it over the years, its likely due for some work, one of the most common issues is users allowing the bearing to run dry at the top sleeve, this causes a myriad of problems as the bearing becomes quite tight causing a lot of drag, it takes out motors and drive systems over time if not dealt with. Its not a difficult fix but requires some special tools and care to restore the bearing sleeves to proper operational condition. I have a good relationship with Oracle, last week I was on the phone with the boys for 2 hours working through an extensive restoration and upgrade of a Mark 3 Delphi. This was a special version delphi in the black and gold finish, these tables were a little different from the regular silver and smoked/clear acrylic delphi's that we all recognize. As its the most recent I will post up about this one first, with pics! Sonic Art -ORACLE AUDIO page 1
SonicArt Posted February 27, 2023 Author Posted February 27, 2023 ORACLE DELPHI MkIII FULL REBUILD I will post up details about the MkIII Delphi first as its a fresh job that has just been finished and is back in place at the customers home, playing music again after more than 5 years sitting collecting dust! This MkIII is one of the rarer black and gold Delphis, its not a regular alloy/acrylic machine, the legs on this table are machined from solid brass then gold plated. They are heavy! the whole table is very heavy, this model did not require a counterweight due to the sheer weight of the leg housings floating at the left hand end of the table! The table was in "used" condition, oxidation on the gold plating, wear to the plating on the clamp and top caps of the legs (not something I could do about in the timeframe, but easy enough for the owner to have replated down the track). The drive system was doing what all MkIII tables eventually do, hunting up and down in speed, with no fix available. Oracle spent a long time on this issue and could not create a fix for it, simply the motor drive needs to be replaced. (bear in mind this is a 1985 table, well out of warranty ) The leg internals were original, the felt/foam stars falling apart, rubbers and dampers lose their isolation properties, and the rest is getting old, springs and spring holders are old designs, lots of little things that all add up to noticeable sound changes. The belt was not factory and really needs to be for the Delphi to run its best, past servicing had been haphazard at best (no fault of the owners), and the bearing had been neglected like many, resulting in the top sleeve drying out over time and becoming tight on the shaft, the result of this is a platter that wont do one revolution when spun with no belt (this also accelerates the demise of the motor drive that already has an inherent problem) Platter mats start to decay a little, get sticky and look pretty average over the years, plus the newer Acrylic mats from the MkV on are far superior and a good upgrade at the same time. The Peripheral wave trap starts to harden up on the outside first, cracking and crazing all over, eventually it will go, it doesnt look so nice when its worn, and being right on the edge of the platter makes it very visible! Oracle have a replacement trap that consists of special large o-rings of various thicknesses and elasticity, they look very neat when fitted and freshen up the table whilst restoring the proper function of the wavetrap. So thats the basics, next post we get into the rebuild and what is involved, I will list all the repair & upgrade parts going into this table, and show some photos of the various stages of rebuild.
075Congo Posted February 27, 2023 Posted February 27, 2023 Fascinating article! Bringing the Oracle Delphi 111 back to life must have been a labour of love. Can you give us some idea of how much "time" goes into this work. Restoring a 38 year old turntable would be mighty expensive.
SonicArt Posted February 27, 2023 Author Posted February 27, 2023 Yes afaik my customer is the original owner, purchased back in 1985. I will go into lots of detail over this week as I clean up photos and get them ready to post with the details of what they show. Time spent? hmm a lot more than charged, but I enjoy doing this stuff too, I was never in it to be a millionaire
klm Posted February 27, 2023 Posted February 27, 2023 If they originally lived in Sydney when they bought it, I know them. There was only one bought in by Audio Excellence when they were the distributors but that was 1989. Exactly same arm and Madrigal cartridge, strange coincidence, they owned a gym out at Penrith.
SonicArt Posted February 28, 2023 Author Posted February 28, 2023 Could very well be, but we will leave them their privacy, I am not sure if they are members in here, if so they will likely see this
SonicArt Posted February 28, 2023 Author Posted February 28, 2023 Ok on with the show! DELPHI MK3, unused for over 5 years, sporadic servicing during its life, following issues known: 1. Motor drive developed the dreaded speed hunt, Oracle was never able to fully sort this bar replacing the motor drive unit completely, so they developed a replacement kit that uses the Mk6 drive system (now Mk7 but not yet released afaik) 2. Bearing was very tight, worst I have ever come across, due to lack of oil and the bushes were a slightly different material to earlier ones, larger shaft too, they get tighter than the earlier ones if let go. 3. Leg internals were to put it simple, knackered! cracked rubbers, felt/foam stars crumbling to dust, old springs and holders, one holder was broken and strapped back together with wire... 4. Platter mat was getting gnarly, pitted and sticky and generally just looked average. 5. Gold plating was oxidized all over, with top caps and clamp rubbing through to the nickel underneath on the edges from handling over the years. What the owner wanted to do: Get it running again! and upgrade anything that could be upgraded easily to MK6 specs or equivalent from Oracle or from me. Now we were limited to upgrading internal components, as there is no way to purchase new housings clamps etc in gold, we had to stick with all the metalwork on hand. In a way this is not a bad thing as the plated parts are all brass! Very heavy, really heavy, the table doesn't need a counterweight due to the extra weight of the brass leg housings on the LHS. So one might be hesitant to inject thousands of dollars into an old Oracle, but this was no ordinary run of the mill early Delphi, its more than just gold plating and laquered spider with black acrylic, the brass legs and clamp, the alloy armboard, the rarity of it, made it worth doing up vs selling it for peanuts and buying a new one for 15k.... Next up getting into it! 1
SonicArt Posted February 28, 2023 Author Posted February 28, 2023 First up the motor drive. Oracle do a kit for converting the early tables to current motor specs, they make a custom acrylic case with the curent alloy motor housing mounted to the top, and the current control PCB in the base. The Mk3 is a little easier to convert vs a Mk1-2 as it has a slot already milled out of the baseplate for the motor assembly to slide into. Of course nothing is ever simple! While the upper section of the new case dropped into place nicely, only requiring 4 holes to bolt it in, the baseplate with the PCB was a little more difficult. I believe they mill out a section of the baseplate underneath, so that the front end of the board has clearance under the table to sit up flush in the bottom cover. Of course this would usually require sending the baseplate to Canada, and sending it back, a good $400+ in shipping alone. So they added some extra acrylic strips to pack out the baseplate giving us that extra room. Problem with this is the speed adjuster pots now dont line up with the holes in the upper section of the case! Maybe they didnt realise I can mill the base if needed, I have often come across this sort of situation, so I simply discarded the strips, marked out the base, clamped it carefully to the Mill and milled out the extra acrylic for the PCB. This way its factory fitted, everything lines up, my ocd is appeased, and it looks more professional. Photos show the new motor drive top and bottom, you can see the PCB end in the pic of the bottom, it comes right up to the hole for the bearing, original board stopped 30mm before this. After the motor fitting is sorted, the front control panel has to be taken out and stripped of all its parts! The only thing left are the two momentary buttons, lights and the LEDs. This took some time, once stripped I had to go over the board and cut any tracks that may have interfered with the buttons or lights. Then I had to wire in the new ribbon cable to the remaining components, and get it right, as Oracle said, if you get it wrong you likely cook the new motor board! Anyway it was not as bad as they made out, I even deciphered the french drawing of the wiring diagram for converting it So far so good, only about 5 hours into things
SonicArt Posted February 28, 2023 Author Posted February 28, 2023 (edited) Next up bearing and feet. The current models have more advanced feet of course, originally the tables had solid alloy (or brass) feet that simply screwed to the threaded rod sticking out the bottom of the table. Even the Mk5 had solid alloy feet, it wasnt till Mk6 that we saw more delrin added to the design with footer inserts. So like the rest of this Mk3, the feet were brass, gold plated. Cant replace them with new Mk6 ones in alloy, have to keep the gold (and the brass!) so I machined out the feet and made delrin footers to screw into the cavity. I gave them a little more height than factory, with the black base not being see through like other models, you dont notice this. Bearing was soooo tight, not even one turn from the platter with a light push. After a good cleaning I spent about 30 mins working on the top bush to clean up the surface and the teflon fur, finally I got it to the stage where the bearing would drop onto the shaft with no resistance, and no discernible play. The Mk3 has a rubber seal in the base, and should be filled with oil. This should be checked every few years to ensure the oil level is right to the top. After rebuilding and filling, the bearing ran smooth as silk, platter spins for quite some time, many more revolutions than the factory minimum. Photos show feet upgrade, and what the bearing looks like, again its solid brass not alloy, also plated. Another couple of hours gone... Edited February 28, 2023 by SonicArt
SonicArt Posted March 1, 2023 Author Posted March 1, 2023 Once the electronics were all sorted the table was stripped and the base plate buffed with plastic polish and the rather excellent SuperCheap Auto $50 buffer! Lightweight variable speed oscillating rotating buffer, great for dust covers, and just as good on acrylic bases... Baseplate polished up then onto assembly. Motor drive installed, control panel installed, leg base cups and lower shafts installed along with the feet. Next up was leg internals and housings. The internals had definitely seen better days! An Oracle maintenance kit was the order of the day, one with springs, necessary when fitting all Mk5/6 internals into the legs. The maintenance kit is a must for any older Delphi table, it gives you the current springs and holders, the current upper grommets with sorbethane dampers, new felt stars, and big thick sticky sorbethane isolation donuts that hold the spring assemblies into the main leg housings. Also added to the upgrades was the Delrin pillars, the old pillars are metal like all early Delphis, so they transmit high frequencies down the leg into the base. Oracle started using full delrin pillars in the Mk5 on, and then started producing replacement pillar sections for earlier models to create a mechanical filter inside the leg assembly. So new felt/foam stars fitted with the new Delrin upper pillars, all gold plating polished up on the legs, springs calculated for the table series and arm weight, and its all assembled ready to fine tune the spring tensions! Getting the Delphi adjusted is a bit of an art form, takes some time to adjust individual spring tensions, the aim being to have the table bounce up and down vertically with minimal to no side movement. Not an easy task with the various weights distributed unevenly around the spider. I think I was about 10 hours in by this stage, once the table was running smoothly on the bench it was time to put it on a rack, check arm alignment and cartridge, then see if it plays music! 1
SonicArt Posted March 1, 2023 Author Posted March 1, 2023 The big reveal Delphi Mk3 plays music! and rather well too! The table was rock solid, silent operation, and had a big dynamic soundstage, I have no idea on the hours the cartridge has, its a Madrigal which I believe was an offshoot of a hi end Sony cartridge range, may be wrong on this though. I know vandenhul was involved along with a few others, supposed to be a very good cart. It certainly sounds good, picks up a lot of noise on non perfect records but it likely needs some fine adjustment, not having all the info on it or the sme protractor handy I had to go by online specs. Arm distance of 215.35mm pivot to spindle was achieved with calipers, its damn close, whether its spot on within 0.01mm I cant say So thats the end of the story for the Mk3, fine tuning of the arm would likely yield even better results, I will leave that with the owner for now as I had a tight window to do this job. I finish up with some pics of the newly rejuvenated Delphi 3, in all its Italian 80's bathroom splendor! 3
075Congo Posted March 2, 2023 Posted March 2, 2023 Fascinating to read a detailed description of the Oracle Delphi transformation......the range of skill sets you applied throughout is a long list. Maximum satisfaction.
SonicArt Posted March 2, 2023 Author Posted March 2, 2023 Thanks Mick, its definitely a labour of love, but the end result is someone who is very happy and that makes me happy
075Congo Posted March 2, 2023 Posted March 2, 2023 Interested in how you polish various surfaces.......in particular perspex. Is there a specific polishing product you use? I have a second-hand pair of Wilson Benesch Vectors floor standers.......their top surface is a perspex plate.....lots of scratches. Unable to remove so has to be treated in place. Probably the same problem for Turntable Perspex Covers over time.
SonicArt Posted March 2, 2023 Author Posted March 2, 2023 I use an orbital rotating buffer from SuperCheap! 50 bucks, its really lightweight, variable speed, and in a lovely Kermit green For scratches that are pretty noticeable you will need to rub them out first, get some 2000 wet and dry, and a soft block, wrap a piece around the block, dip in bucket of water, then gently rub out the scratches, rinse the paper in the water regularly, and wipe up the workspace with a sponge as you go, this way you wont get water n crap everywhere. Then you will need to use a decent polish with the buffer, I use a car cut n polish paste or a regular car polish first, then to finish, a plastic polish, I use plastX (I think its called) which is a car one and gives a nice shine at the end. It will take time to bring it back up once you have rubbed out the major scratches, but its worth the effort. 1
SonicArt Posted March 8, 2023 Author Posted March 8, 2023 Here are some of the early Delphi rebuilds and upgrades I have done over the years, some I have no photo records of which is a pity, but at least I have some of the ones with custom Sonic Art baseplates. First up is a rebuild Mk1 with new clear acrylic baseplate. It had a full maintenance rekit put through it and a Rega RB250 with Origin Lives early end stub kit fitted. The baseplates were CNC machined locally from my drawings, I did quite a few of these in 15mm acrylic. Second up is another Mk1 with a much more substantial rebuild! I used this table for some time before moving it on, it had Mark 5 legs, record clamp and armboard fitted along with a full maintenance kit. It had one of Origin Live's first Silver arms, with the alloy arm tube sitting in a Rega RB250 base section. A great performing table, someone out there in Melb still has this table for sure! In the background is another Mk1 underway with new baseplate. Yet another Acrylic rebuild, this one with clear lid to match in with the baseplate! This was an interesting rebuild of a Mk1, the control panel was damaged and non functioning, as parts were no existent even back 20yrs ago, I suggested we remove the remnants of the panel, machine the baseplate without the wiring groove to the front, and build a switchbox instead. End result was a very clean looking Oracle, it had all the Mk5 upgrades, legs, clamp, board etc, and actually looked really modern and clean when finished. 1
Frank is here Posted March 29, 2023 Posted March 29, 2023 (edited) Have just found this post...don't know how I missed it....well done Mark...appreciate the time taken to get it up... Interesting work being done by a true professional.....Have dealt with Mark for Oracle parts over many years....very honest and trustworthy .....great communication with great product knowledge ...... Mark is always happy to help...... Check SonicArt website.........he has other great stuff as well..... Edit:...have just searched Oracle on StereoNet and found other articles re Mark.......well done Mark.........great reading for us Oracle'ites....... Edited March 29, 2023 by Frank is here Found more information thus edit update
SonicArt Posted March 29, 2023 Author Posted March 29, 2023 Thanks Frank, I know you love your Oracles too! I have been working on a lot of upgrade parts over the last few weeks, I now have upgrade suspension pillars for Mk1,2,3 & 4 available, custom made here by me, Delrin pillars or pillar inserts. With the Mk3 it has an interesting pillar upper section, it was the first Delphi to have solid top caps, they dropped down onto a pin with a locating spring pin allowing one to turn the upper section of the leg to adjust the overall height once the springs were set. Factory upgrades have been available for some time, quite costly though. My solution uses the original pillar section, modified to screw into a delrin spring support, which screws into the leg base like the original. I feel its a stronger solution, and being local, a lot more affordable. 1
075Congo Posted March 23, 2024 Posted March 23, 2024 Mark, Looks like one of the ORACLE Turntables you upgraded is being followed by lots of members in the Classifieds. A beautiful piece of work on your part. Cheers Mick 1
audiodyna Posted March 24, 2024 Posted March 24, 2024 Hi Mark, It's such a delight to read the full description on the upgrade. Me and a few friends are presently using the Delphi Mk 4 and had been looking around for experienced repairer for quite some time. I will spread the good news to my friends.
audiodyna Posted March 24, 2024 Posted March 24, 2024 4 hours ago, 075Congo said: Mark, Looks like one of the ORACLE Turntables you upgraded is being followed by lots of members in the Classifieds. A beautiful piece of work on your part. Cheers Mick Hi Mick, I had been following you on your interesting news and articles. This one is really making a lot of my friends very happy. Thanks. Cheow
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