2. My MKIV has a custom sized Boston Audio Mat which I still use the clamp on. I've tried almost every mat out there on my Delphi and found I really like the Boston Audio, other than it does seem to create a little static.
I haven't had a Delphi III for years. But when I did, yes, I turned the platter off each time I changed a record. I always used the supplied Oracle "Groove Isolator" mat with the clamp and spacer-washer. When I traded up, I sold it to a friend who still uses it along with the Fidelity Research FR-64 pickup arm he also bought from me.
Thanks all. It is good to know that I am following the same routine as others. I wasn't sure as it seemed that switching on and off every 20 mins would overly burden the switch and motor. I guess, conversely, trying to change a record whilst the platter is moving is also going to put additional stress on the motor when trying to tighten up the clamp.
Thanks for all your feedback.
I have had 4 Delphis. II.5 and II.7 with the GROOVE ISOLATION w/ clamp & space-washer were the best hands down in audio quality. Because it´s the best record clamping system there can be. Platter + GI + record become one unit. Never liked the hard mat nor the stiffer suspension of IV, nearly impossible to fine tune the otherwise great suspension and sounded just awful. The get the best out of an Oracle its suspension must be in perfect balance. No exceptions. The micro detail sound is very hard to beat, for any deck.
Using Reso-Mat on the original GI mat is another thing. And you can use the original clamp as a weight. It even sounds very very good :) IMHO
Haven´t had static issues with Reso-Mat either.
Hi Harold, with regards to the suspension tuning / balancing is there anything other than ensuring the distance between the plinth and the underside of the suspension housing on each pillar is equal to the "B" point of the suspension gauge (21mm). And also making sure the correct spring is used in each location.
Is there a further check that needs to be done. I heard there was a bounce check but i don’t know what that is. What would you advise to ensure perfect suspension tuning.
Also what are the effects on either side of the ideal setting. Does the bass get flabby with looser suspension or does the treble rise with a stiffer setting.
Any observations you may have would be most welcome.
ateal OP" ...with regards to the suspension tuning / balancing is there anything other than ensuring the distance between the plinth and the underside of the suspension housing on each pillar is equal to the "B" point of the suspension gauge (21mm). And also making sure the correct spring is used in each location.
Is there a further check that needs to be done."
Yes. When excited - tap on the platter vertically - the platter assembly should vibrate in a purely vertical, pistonic manner, with no wobbling from side-to-side. If it wobbles, either the tower heights are not properly adjusted, and/or one or more springs must be twisted (without changing height) so that the ends of the coil of each of the three springs share the same orientation.
After getting great advice here, I went home and did the bounce test. I gave it a little tap on the top of the clamp and watched the bounce. The results seemed good - the bounce remained completely vertical just like a piston, I didn't notice any lateral movement. The actual bounce from a single light tap seemed to go on for at least 15 to 20 cycles which seemed higher than I have read elsewhere on the web. Not sure if that is too much bounce?
Also the bounce came to a gentle stop with very tiny movement towards the end. This indicates to me that there is nothing hindering the bounce.
Any comments from current or previous owners more than welcome.
You will destroy the belt if you don't turn the motor off at a change.
Look at the Oracle-audio.com site for instructions- the later instructions (Mk IV and up ) are better (just ignore the MVSS part). The Mk III can be updated to later versions when you get ready. Try to get the most recent belt and bearing available for the Mk III as an update. You can also get a later mat to replace the groove isolator mat, but if it weighs more, you will have to re-balance the suspension and perhaps replace the springs (don't go there). You might try to contact Herbie to find a mat at the exact diameter (with a satisfaction guarantee). Also get a washer from him to replace the original tapered washer. Always use the clamp. Do not replace it with a heavier clamp.
It would be foolish to replace the GROOVE ISOLATOR . So is replacing the original soft suspension. Fine tuning becomes much more difficult. So does finding the right tune/sound balance. There´s no real advantage when things get more complicated. The sound surely becomes different but not necessarily better. The GROOVE ISOLATOR / clamp system gives THE best audio w/ HQ high compliance cartridges. Period.
I never liked the sound of stiff suspension with hard mat @ Mk VI.
At the time I didn´t have a HQ MC to try so I say nothing about MC carts.
Best of Luck
Thanks for the feedback oldears.
Thanks Harold, what exactly is the GROOVE ISOLATOR, is it a mat. The mat I have is the Audioquest sorbatane mat and it appears to be in good condition and not too sticky. Did you ever have this mat? Should I keep my eye out for an alternative?
Also does anyone know what happens to the sound, the firmer you make the suspension.
I have learnt that the current location of my springs in relation to the suspension housing is at the limit recommended in the manual, i.e. when i lift the sub platter my springs are flush with the suspension housing and no excess springs are showing underneath. This setting places the suspension housing 18mm (not 21mm) above the acrylic base.
I think this is why my suspension is quite springy and gives me plenty of bounce cycles. What I may do is re-do the suspension making sure I am 21mm from the acrylic base and in turn this will keep a little of the spring showing under the suspension housing and slightly firm up the suspension.
The manual states that after adjustment to 21mm the springs should either be flush or up to 3 spring wires showing below the suspension housing. If you are in this range and all springs are even then I guess you have the correct springs.
What a great learning curve this is on such a beautiful looking and sounding table.
I have the Oracle SME 345 tonearm on mine and I just got the SRA spot on last night while listening to the 45rpm version of "Jacintha - Jacintha is Her Name" album. Man, that "Willow Weep for Me" was sublime and intoxicating. The fine detail that was revealed and the the tone of her voice and saxophone was as real as I have ever heard.
ORACLE GROOVE ISOLATOR
The ORACLE GROOVE ISOLATOR is made from a vinyl based compound which is electrolytically positive charged. Since all record vinyl exhibits a negative charge, the two are electrostatically opposite therefore creating the apparent "stickyness" through electrostatic attraction. This is not a chemical bond, such as what would be found with Sorbothane or even glue.
ateal " ... I have learnt that the current location of my springs in relation to the suspension housing is at the limit recommended in the manual, i.e. when i lift the sub platter my springs are flush with the suspension housing and no excess springs are showing underneath. This setting places the suspension housing 18mm (not 21mm) above the acrylic base.
I think this is why my suspension is quite springy and gives me plenty of bounce cycles. What I may do is re-do the suspension making sure I am 21mm from the acrylic base and in turn this will keep a little of the spring showing under the suspension housing and slightly firm up the suspension ... "
As I recall, adjusting the Delphi III's tower height does not change the tension on the springs - only their height. The turntable is designed to be "springy" and performance will likely suffer if you try to "firm up" its suspension.
"As I recall, adjusting the Delphi III's tower height does not change the tension on the springs - only their height. The turntable is designed to be "springy" and performance will likely suffer if you try to "firm up" its suspension."
Exactly. I owned one Black/Gold III 25 years ago. Gorgeous machine. Alas, it was impossible to fine tune because the location of towers didn´t match the upper chassis tower holes exactly. Sounded good though. But I never could get the best out of it. What a shame :/
Thanks Cleeds and Harold for the advice on the suspension.
Harold, can you clarify that problem you had with your MK III and how it adversely affected the tuning. Do you mean the 3 holes in the aluminum sub chassis did not correspond with the 3 holes in the acrylic deck. I guess that would mean one or more of the towers were skewed in the vertical plane.
If that is the case then that must have been a poor factory quality control issue and I agree such a shame.
I replaced the original mat on my Mk I Delphi with a mat like the one on the Goldmund many years ago. The sound was better IMHO, but it was a heavier mat, for which I was able to correct the suspension by changing the springs. I now have a Mk V with the new type mat (I don't think Oracle made a mistake). I suggested the Herbies mat and washer as a trial because it has a satisfaction guarantee, I have not used one personally. The original mat should be cleansed periodically with dish soap and water.
Changing the height of the towers also affects where the belt rides on the inner rim. if you get it too high, the belt will not stay on the rim. On my MK V the height of the skirt above the base is 18 mm with a record and clamp on the platter. i just checked and it bounced about 25 times.
If the Mk III has the newer style 2-piece bearing, contact Oracle to see if you can update the bearing bottom for the one on the MK VI with a polymer thrust pad. It is a big improvement. Also get a new belt and bearing oil.
oldears, thanks for the tip re. the Herbies mat, I may give that a try. As for the belt ride height I checked last night and it sits square in the middle of the inner rim, so I have some room to maneuver up or down if I need to.
Also it sounds like we both have our suspension set exactly the same at 18mm with similar bounces. That's good to know.
With regards to the bearing I am not sure if I have a 2 piece or 1 piece. I do know that I can remove the bottom of the bearing and flip over or replace the thrust pad. How do I tell if I have 1 or 2 piece bearing?
Thanks for the clarification oldears and harold.
I fitted my Fidelity Research FR1 MK3F LOMC cartridge this weekend and even though it is considered a low compliance cart (10cm @ 10Hz ) it matched perfectly with the low mass Oracle SME 345 tonearm.
I now feel I have my reference TT / Arm / Cart combo.
I wanted to see if an acrylic mat would make the improvements Oracle claimed if I 'upgraded' from the Groove Isolator, as they recommended, but didn't want to pay the hefty price for the new mat and modified clamp. I thought I'd experiment with a cheaper acrylic mat first; but couldn't find one that was both 3mm thick and 289mm across. I asked an Ebay seller if he'd make one for me and woodendan was kind enough to do so. If your interested, ask him for the new size. I haven't done enough listening yet to decide on my Alex; but I love it on my Linn Basik!
Merlinm3, if your question was directed at me, I apologize for the slow response. I forgot to check off ’follow this thread’. I did fool around with the non-Oracle acrylic mat more after my post. I found the best arrangement was to place the washer on top of that mat. It sounds very good; but I prefer the GI. A tad more ’body’ to the sound. I may try some tweaking - rough-up the platter side or tac it down with some Duco that can be easily removed. And it is nice to be able to play with matching mats with cartridges. The GI with my dynavector and Denon, the acrylic with my Shure.
I have another question for the experts. I recently came into possession of the felt mat that Oracle sold with the Alex MK III and MK IV. It is by far the nicest felt I’ve ever seen or heard, a 3 ply affair consisting of soft felt/stiff fiber/harder, smoother felt. It is difficult for me to tell if there is much difference in SQ from the GI. My question is, why do you think Oracle made the switch? Does it mate better with the MK III & MK IV, or was it a cost savings compromise?
Does anyone have any insight?
I now have an Alexandria MK III. It has a platter that is quite different than the MK II, one piece with no lip or wave trap. I spent some time comparing the 3-ply felt mat, a Pro-Ject cork-it, the Groove Isolator, and the custom acrylic. The differences are not monumental; but on the MK III I like the acrylic better. The most notable change is more vertical dimension to the soundstage. The cymbal sounds distinctly higher than the bass drum. I like it and I'm thinking of going semi-permanent with double sided tape. I wish I could find a convex model at a reasonable price. I still like the GI better on the MK II, which I will probably sell. I am not sure I will be able to part with the GI, however.