Oxford Crystal Reference restoration

[peter]

Here is a picture of my very sad looking Oxford Crystal Reference TT, in need of restoration. It's not been used since my Premier 4 (also pictured) blew up over 10 years ago.

I would now like to play vinyl again, but the TT has many design issues and I need help from anyone who has some experience with this product to help me get it working properly.

Oh yes, and hello to everyone!

Peter.

[chris@panteg]

Hi Peter

pop into the welcome area and introduce yourself , if you could .

i remember this deck very well , sounded amazing at the time i heard it (1988)
i think Guy Sergeant might know something about these ? not sure or perhaps Mark (ynwan) , the arm is the Air Tangent (air bearing) i believe , and uses some kind of pump ? is that still working .

[peter]

Hi Chris,

Indeed the Airtangent is the original (Mk1) version with the heavy counterweight fitted. Just turned the pump on and it still runs, no cartridge fitted ATM so air bearing may or may not be ok but it seems to slide nicely. Also the turntable powers up and goes around (which considering the tiny 22 year old rubber belt used is a minor miracle!).

Turntable serial number is CR-059, and was made for me in Q1 1988.

The main problems are

(1) The sorbothane isolation disks cannot support the weight of the sub-chassis and after multiple failures (from day 1 really) have since been lost/discarded. Need to obtain an effective replacement that does not inject any sonic signature (my own attempts all seemed to colour the sound).

(2) The platters/bearing, something causes the TT to "wobble" when correctly set up, If you set the TT to eliminate the wobble it effectively becomes a swinger. In both cases there is a subtle wow. Could be a symptom of problem (1).

(3) The top platter has a dish machined into the top surface so the weight holds the record in contact. However this slope causes the arm to skate inwards and IMO effects tracking. IIRC the air-tangent is set up so that it neither skates in or out when correct on a flat/level TT. The slope also means the cartridge is not perpendicular to the record surface and the arm also appears to "run down hill" because the headshell is not parallel to the surface of the platter which means that the tracking force varies according to the music in more ways than you can think of!

(4) Lots of dust, obviously

It seems that however you set up the TT something is not right. At this stage it would be nice to know if mine is the only one with these problems.

I had borrowed a Koetsu Platinum Signature and this was the only time I remember it being right, as if the cartridge didn't really care about its alignment. When I found out how much that cartridge would cost I gave up the challenge. I took the cartridge out and forgot about it. Next time I turned the system on there was a loud crackle when my fingers brushed against the bare cartridge wires and that was that.

Peter.

[YNWaN]

Hello . I remember the Oxford Crystal but never studied the specifics closely I'm afraid.

You can actually buy Sorbothane in lots of different grades depending on the weight it will carry; have a look on-line. To experiment (don't laugh) you could try buying posh insoles for running shoes - these are often made from layers of different density sorbothane and can be cut up with a pair of scissors.

Not sure about the 'wobble' issue - you will have to be more specific in your description.

Pics of the whole thing taken to bits would help.

The platter really needs to be taken to a machine shop and have the concave surface machined off IMHO. There was a definate fad amongst manufactures for this solution but, whilst superficialy a good idea, it didn't work very well.

[peter]

I will take it apart this w/e as I have to relocate it anyway and take pictures.

>> have the concave surface machined off IMHO

Interesting. Do you think the top platter surface should be polished or rough?

I have thought about flipping the top part upside down, and putting some kind of mat in the space between the two sections. But then there is no central cutout where the LP label is. Hmm.

Another manufacturing flaw with the TT is that the two platter parts actually have a tiny gap (you can get a bit of paper beween them in places so there are areas where there is no contact). I don't know the theory behind a two section platter so don't know what the ideal material would be (if any). Perhaps an air gap all the way around is even desirable.

By "wobble" I mean that you can see the cartridge move up and down a mm or two (from memory) as the platter rotates when playing a flat record. It is very obvious at 45 rpm. This means that the spindle is not actually pointing perpendicular to the reference plane. and the whole bearing/platter assembly is precessing (?) a little. The bottom part of the bearing housing can be adusted so that the wobble is reduced to zero, but the centre of rotation is then effectively offset so you get the same effect as a "swinger" like an LP with the hole slightly in the wrong place. But of course the centre of inertia is then not in the right place either, and the belt tension varies during the revolution, etc. It's clearly preferable to put up with the wobble.

I should point out that this not a new phenomena. The TT did this from day it was installed. At the time I looked at other Crystal turntables and they all did this to some degree or other. I was told that it wasn't significant, but I believe it is why the next killer turntable on the block (the first Basis ?) buried the Reference sonicly without all the fuss and weight, because it was rotationally utterly stable.

A big irony is that one feature of this turntable is that you can remove the centre spindle and position a real swinger so that it does not swing!

I have seen sorbothane turntable feet as well as bushes and all kinds in varous grades. I'm spoiled for choice really. I am hoping someone knows the right one for this TT. This needs to be sorted before investigating anything else really as the sorbothane supports sets the level of the TT. again

Peter.

[DSJR]

This deck was suposed to have superb machining and it sounds to me as if there's dirt of grit in between the platters preventing them from mating properly (?)

The dished platter may not be a huge problem with conventional tonearms as increasing the bias slightly would be enough to counter things (and possibly tilting the headshell ever so slightly too, to maintain channel separation). Obviously with a linear tracker, the dishing will cause some artificial "bias."

I only saw one of these once and at first I was confusing it with memories of "The Source." Try Oxford Audio Consultants, West Midlands Audio and Acoustic Arts (if he's still trading from home) - and other Absolute Sounds dealers of long-standing and see if any of them know about this deck. They're the kind of people with rich clients for these

Good luck

[Spectral Morn]

This deck was suposed to have superb machining and it sounds to me as if there's dirt of grit in between the platters preventing them from mating properly (?)

The dished platter may not be a huge problem with conventional tonearms as increasing the bias slightly would be enough to counter things (and possibly tilting the headshell ever so slightly too, to maintain channel separation). Obviously with a linear tracker, the dishing will cause some artificial "bias."

I only saw one of these once and at first I was confusing it with memories of "The Source." Try Oxford Audio Consultants, West Midlands Audio and Acoustic Arts (if he's still trading from home) - and other Absolute Sounds dealers of long-standing and see if any of them know about this deck. They're the kind of people with rich clients for these

Good luck

These are the people who had involvement in Oxford Acoustics at the time though if I remember right the main guy moved on John something or other I can't remember sorry.

The deck needs to be taken to pieces and each section cleaned. The platter is probably not responsible for the arm problem.
My gut feeling is it is an issue with a part or parts not being level. Dirt under the platter could cause this slight rise and fall as could damage to the bearing. However it is hard to say with certainty without seeing the TT in the flesh.

Air bearing arms are exceptionally fussy about every part being level and the arm tube being clean (use isopropanol). Each part of the TT must be level and the deck must be set up on a concrete floor. Once the TT is level then check the arm mounting and arm are fully level. Then you go about setting up the arm cart etc, VTA, HTA etc must be 100% right.

The sorbothane is an issue as if I remember right I think different types were used in different areas to compensate for weight distribution and these had to be placed in the right spots.

This was a fantastic TT in its day and I would love one but I can't afford it. It is imho worth working on this to get it right as this TT and the NA Mentor Reference are seminal memories of mine, as to what at the time I thought was fantastic in TTs

Snoopdog (an AOS member) owned an Oxford (up until recently) so he should be able to help a bit....I wanted to buy his at the time he was selling but he would not sell without the SME 5 arm on it and I did not need another one.

Don't give up on this.

I would love an Air Tangent arm too. I have an Oracle Delphi and I remember seeing photos of them with AT arms on them at the time 20 years ago or so.

PS Can you pop into the welcome section and say hello, tell us a bit about yourself, taste in music and current system.

Additional info it was Jon Harker and the dealers that DSJR mention were the main dealers for the TT. If I remember right Oxford Audio Consultants came out of the ruins of Oxford Acoustics when they went tits up.


Regards D S D L

[peter]

You guys are pretty spot on. I'm not sure if I should name names but yes, the turntable came from Acoustic Arts. I had booked their rooms in Watford to audition valve amplifiers over the christmas period. I had moved my entire system down there and as we were running out of time decided to leave it all there for the holiday. Later on a van reversed through the plate glass window toppling an equipment rack which had an Oracle Delphi and Airtangent on top. The arm was literally bent through 90 degrees. My turntable (then an Oracle Alexandria) was stolen (later recovered). Given that the air tangent was unsellable it became part of a deal which included a new Oxford Crystal Reference TT (which was the latest thing at that time), the Air tangent is designed for easy arm/cart swapping so the broken arm was easily replaced.

When the Oxford folks (Fraser Shaw & Jon Harker of Oxford Audio Consultants) put the system together prior to delivery they found that the Air Tangent Air Beam was also very slightly bent causing it to stick, so they arranged to have the arm shipped to Sweden to be repaired by the Stig himself. Meanwhile they installed the turntable at my old house with a well-tempered arm to keep me in business.

Unfortunately there was a problem with the top platter rotating against the bottom platter due to manufacturing defects. This causes scoring of lacquer on the bottom platter when small bits of dust gets trapped between (it gets in through the gap) and when you clean the metal section the polish can enter if you're not careful. So they took the TT away and reground/relaquered the various parts and when the airtangent returned they re-installed the turntable with it at my new house.

I mention this because these guys really did bend over backwards to get the TT going to my satisfaction, I don't think the Airtangent is a good match for the deck and the SME V would be a better choice for the alignment reasons given already. If it had worked then maybe the other problems would have been overlooked. My ultimate choice of Cartridge was also a factor in it not working. In the end Oxford Acoustics where not successful and it became impossible to get support, and I don't want to hassle them any further.

At the moment I would certainly consider exchanging the turntable (assuming it can be restored) for an Oracle Delphi so you never know. You must understand that it is high maintenance, requiring constant polishing, cleaning and removal of dust.

I cannot in all conscience let the Air-tangent go though as it has been in the wars. It is also a Mk1 and I am told quite inferior to the Mk2.

peter.

[Spectral Morn]

You guys are pretty spot on. I'm not sure if I should name names but yes, the turntable came from Acoustic Arts. I had booked their rooms in Watford to audition valve amplifiers over the christmas period. I had moved my entire system down there and as we were running out of time decided to leave it all there for the holiday. Later on a van reversed through the plate glass window toppling an equipment rack which had an Oracle Delphi and Airtangent on top. The arm was literally bent through 90 degrees. My turntable (then an Oracle Alexandria) was stolen (later recovered). Given that the air tangent was unsellable it became part of a deal which included a new Oxford Crystal Reference TT (which was the latest thing at that time), the Air tangent is designed for easy arm/cart swapping so the broken arm was easily replaced.

When the Oxford folks (Fraser Shaw & Jon Harker of Oxford Audio Consultants) put the system together prior to delivery they found that the Air Tangent Air Beam was also very slightly bent causing it to stick, so they arranged to have the arm shipped to Sweden to be repaired by the Stig himself. Meanwhile they installed the turntable at my old house with a well-tempered arm to keep me in business.

Unfortunately there was a problem with the top platter rotating against the bottom platter due to manufacturing defects. This causes scoring of lacquer on the bottom platter when small bits of dust gets trapped between (it gets in through the gap) and when you clean the metal section the polish can enter if you're not careful. So they took the TT away and reground/relaquered the various parts and when the airtangent returned they re-installed the turntable with it at my new house.

I mention this because these guys really did bend over backwards to get the TT going to my satisfaction, I don't think the Airtangent is a good match for the deck and the SME V would be a better choice for the alignment reasons given already. If it had worked then maybe the other problems would have been overlooked. My ultimate choice of Cartridge was also a factor in it not working. In the end Oxford Acoustics where not successful and it became impossible to get support, and I don't want to hassle them any further.

At the moment I would certainly consider exchanging the turntable (assuming it can be restored) for an Oracle Delphi so you never know. You must understand that it is high maintenance, requiring constant polishing, cleaning and removal of dust.

I cannot in all conscience let the Air-tangent go though as it has been in the wars. It is also a Mk1 and I am told quite inferior to the Mk2.

peter.

They were Oxford Acoustics.

Hi Peter sorry to read of all your disasters

To be honest I would not want to sell or swap my Oracle however if the Airtangent works fully (and the price were right) I might be interested in it even if it is perhaps not cosmetically perfect.

What kind of mounting does it need ?

Yes the MK2 was better.

Regards D S D L

[Snoopdog]

Hi Peter

Oxford Acoustics was started by Jon Harker (owner/operator of Oxford Audio Consultants since 1990) and Fraser Shaw (a surgeon by profession) in 1986.

I purchased an Oxford Acoustics Crystal Reference tt with SMEV from Subjective Audio (Howard Popeck) in 1987 following a demo conducted at my home with Howard, Jon, Fraser and a very nice curry.

I owned that turntable until I sold it last year to Bob (It Costs How Much? - on HifiWigwam).

If you pm me your home email address I can send you a very comprehensive setup document that I compiled for Bob which also contains many tips I picked up over my 21 years of ownership.

I only sold the Oxford because it took up such a large footprint and I wanted a smallish tt I could site on the top shelf of my equipment rack.

The early sorbothane 'walnut whips' were soon superceded by a better design which did not sag over time (sounds like you have the early design).

I did have a plan to replace these with 3 X Stillpoints and I would be happy to discuss with you further how you might go about incorporating these into the Oxford design.

Oxford Acoustics were very much ahead of the game back in 1987 when the popular view was that only a suspended sub-chassis turntable would cut the sonic mustard. Jon and Fraser had some ambitious plans which included incorporating a mc phono stage in the top of the plinth. DIN sockets on the outside rear were installed for this purpose and to link to the power supply for the turntable.

Ultimately, Oxford Acoustics ceased to be when Fraser returned to medicine and Jon became a hi fi dealer.

In the meantime, a nostalgic pic to ponder