Roksan xerxes

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Ant
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#1 Roksan xerxes

Post by Ant »

I got a roksan xerxes in to look at. A very early one given the serial numbers, the deck is a mk1 1985 example. the psu is a very early xps2, it still has a switch on it rather than buttons to change speed, so presumably a replacement for a blown up original.

It has the classic xerxes issue of a sagged top plate, and the classic xerxes issue of a psu that is broken.

The motor gives a twitch when turned on, but doesnt spin, suggesting one phase is not working in the psu. This could be a number of things, from caps, to the output devices on each phase, to the oscillators. So a long fault finding job. Or a new power supply which is a few hundred quid.

The psu has practically no ventilation, there are 3 holes in the back and 3 in the baseplate. its a pair of anodized aluminium bent panels with a veneered mdf cover over the top. So is effectively insulated. By the mdf trim.
No wonder these psus blew up from heat, the output devices have crappy little heatsinks and there are a pair of 5w coffin resistors which also get very hot, and there is practically no way for the generated heat to get out. Silly design flaw.

The top plate sag can be dealt with in a number of ways, roksan had a bodge that shimmed the bearing up so the platter cleared the none sagged bit which is practically useless as the motor and bearing are no longer aligned properly because of the sag which isnt dealt with by shimming it up.

Second way is to put a plate underneath the gap and force it into line, not a great way as the plate will be pulled down under tension from the sagged section

Having had a think, a better way would probably be to use some clamps to force it straight, then drill 2 holes horizontally through the vertical side of the plate, and into the sagged section and insert a pair of rods so eveything is held in alignment

Then just make a new top plate using the original as a template if i can get the thing running.

I think the cutout is also abit misunderstood, people seem to think its there to decouple the arm and bearing from the motor but its not. Its there to break up resonance in the top plate, so bridging the cutout to cure the sag shouldnt cause issues with the resonance control its actually there for, especially if the rods are acetal or similar

I need the top plate to be flat so i can fault find the psu under load, if i cant put the platter on properly and have it run i cant test under load

Its also missing a foot.

Could do with a new belt

And the bearing oiling

Cosmetically its very clean, very black and very 1985, even the black lid is cosmetically very black and not scratched.

Given all the work it needs and the potential hours it will need putting into it to get it recommissioned, the owner was going to part it out and try to sell off the good bits, so instead ive bought it as is for not alot of money.

It has an rb300 on it with an ortofon mc1 turbo, the 300 has had an epoxy repair done at some point to repair a crack in the plastic outrigger. It is perfectly servicable but the repair is visible.

Im confident i can repair it, the psu isnt particularly complicated and if push comes to shove every single component can probably be replaced

I havent had a belt drive deck in years, it will be an interesting project
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IslandPink
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#2 Re: Roksan xerxes

Post by IslandPink »

Sounds like you're up for the challenge !
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Ant
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#3 Re: Roksan xerxes

Post by Ant »

Success!
I've had to put in about 15 hours in over the last 2 days to get it running, but it runs!

Image1985 roksan xerxes rb300 ortofon mc1 turbo by anthony cresswell, on Flickr

The power supply required a couple of caps replacing, I went through every component on the board and checked each one apart from the output devices because i couldn't tell what they were because of the heatsinks and didn't want to disturb them. I'll replace all the caps. There are probably more potential gremlins in there but the objective was to get it running first.

The motor sits on a bearing so that it can rotate around its own axis, and it needed the pulley azimuth setting, this was a pig to do, but as the deck has 3 feet it could be positioned to hang over the edge of the rack so i could get to the adjustment bolts.

I fixed the sag by inserting rods to correct it before digging into the psu because the platter was dragging on the plinth so it wouldn't spin

Image1985 roksan xerxes rb300 ortofon mc1 turbo by anthony cresswell, on Flickr

there is another rod further to the left as the sag was worse closer to the bearing so it had to be pinned in 2 places to make sure that the cutout was flat all the way across. some people would say this ruins the xerxes, they may be right, i wouldn't know if it sounds any different to a none fixed one. But at the end of the day, its either do this, or its scrap.....

I'll make a new top plate at some point to compare.

Image1985 roksan xerxes rb300 ortofon mc1 turbo by anthony cresswell, on Flickr

The psu gets hot after about 2 and a bit sides, unsurprising given the complete lack of sufficient ventilation, so i'll modify the case by cutting a bloody great hole in the top and putting mesh in said hole. After all the design effort that went into the deck its hot running is a surprising oversight.

The rb300 sounds like an rb300, its lack of vta adjustment is a pain in the arse, and the ortofon mc1 turbo cartridge is passable. I was surprised that it worked at all to be honest.

It needs the arm shimming up to get the correct vta so i'll have to bodge it up to get the right vta for the cartridge then turn an acetal shim as a proper fix.
The top plate position is also a right pig to get right as it cant touch the outer frame, but also sets the belt tension as the motor is in a static position but the bearing can be moved relative to it.

as it is, with incorrect vta it doesn't sound bad. Ive heard worse.
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#4 Re: Roksan xerxes

Post by Cressy Snr »

I heard it this afternoon. It’s a lovely turntable. Sounds very clean with great bass and has a very similar presentation to the Roksan Radius 5 I used to own. The Xerxes has a bit more weight and authority than the Radius, and so it should really.
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Ant
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#5 Re: Roksan xerxes

Post by Ant »

Did the simplest bit of the things I want to do to it first, and sorted out the vta problem.

this is how it was

ImageRb300 vta by anthony cresswell, on Flickr

Right down at the back so the vta was a mile out

Now its correct

ImageRb300 vta by anthony cresswell, on Flickr

After bodging the arm up to the right height for the correct vta, I then measured the gap and just turned a simple shim

ImageRb300 vta by anthony cresswell, on Flickr

as you can see the 300 is substantially out, the shim had to be 4.5mm tall. This then causes other issues as the retaining nut is barely on there because the plinth top plate is 25mm thick, and the pillar is 30mm long..... There is just enough to get it grab.

The cartridge is quite tall at 18.5mm, my at33 is shorter at 17mm, but there are plenty of carts around the 3/4" tall mark. A proper vta adjuster could have been made, but that would require modifying the top plate to accommodate one which I don't really want to do. I might as well make a new top plate for it if I have to start hacking it around.

I can now risk playing some of my normal records on it now rather than the few I have that i use as setting up discs
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Ant
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#6 Re: Roksan xerxes

Post by Ant »

Some observations from listening to the deck/arm/cart combi.
It seems to be devoid of character, which is both good and bad. Good because i can tell im listening to an rb series arm, and bad in the sense that it doesnt have much 'feeling' to it.

Uncomplicated tracks are pleasant, more complicated tracks start to fall apart quickly and it becomes difficult to follow.

There is a decent sense of space, leading edges of everything seem to have a bit of a smear to them as if everything as a hair out of focus. Midrange is abit recessed and the soundstage is flat. not much in the way of depth but it is nicely wide. Its all abit hazy and disjointed. Like an lp12 but lifeless

Dynamics are..... not. Compared to my other decks its as flat as a fart

Good points, after years of idlers, this deck is deathly silent in the groove, so quiet that i had to check that the arm had actually dropped onto the record. My collection of lencos is rather quiet, but not like this is. Its very pitch stable for a belt drive.
The bass on it is very good indeed, really tight, really nuanced. I was not expecting that

Overall, it is bland an uninteresting with this arm and cartridge. If i had gone into a dem room in 1985 and listened to this combination i would have bought something else.

However.

The fact that it is devoid of any character that i can point at leads me to the conclusion that its not so much the deck itself, its the rb and ortofon that are the main culprits. I dont get on with ortofon carts, other than the spu and sl15, and find the rb series of arms to be dull as ditchwater. the combo just doesnt gel in any way, it just doesnt hang together very well

It the performers seem like they cant be bothered..

As it is, it sounds uninvolving and underwhelming

Ill put a different arm and cart on it, i think there is much more to come from it
Last edited by Ant on Thu Mar 10, 2022 10:09 pm, edited 2 times in total.
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#7 Re: Roksan xerxes

Post by IslandPink »

Yes I'd say the arm could be the biggest culprit here.
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#8 Re: Roksan xerxes

Post by Cressy Snr »

Put your unipivot on it.
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andrew Ivimey
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#9 Re: Roksan xerxes

Post by andrew Ivimey »

Erm, I have a roksan tone arm on a goldring gl85. I had no great expectation when I bolted it on and switched on. I was astonished and surprised.

And years later I am still very pleased. The deck had previously an rb300.
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#10 Re: Roksan xerxes

Post by Ant »

I did a lenco for a customer that had a tabriz arm on it and was impressed with it. It had a wierd counterweight that hung on a single point which i spent a good deal of time pondering over..

My arm wont go on it without making a longer mounting collar, the top plate is too thick. Either that or dismantle it again and machine a recess under the arm mounting hole which id rather not do if i can avoid it

Hmmm
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andrew Ivimey
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#11 Re: Roksan xerxes

Post by andrew Ivimey »

Tabriz it is - couldn't 'member. Imho, superb!
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#12 Re: Roksan xerxes

Post by Daniel Quinn »

I have a roksan Tabriz zi and a rega 300 .

I must be deaf as I can’t tell them apart .

As a matter of engineering I’m of the opinion that the rega is better
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#13 Re: Roksan xerxes

Post by andrew Ivimey »

Engineering ..... hmmmmm, I've had both rb300 and Tabriz - I was able to compare them close to side by side as the rb300 went out the door straight after I got round to selling it and fitting the Tabriz. Same cartridge, straight on.

I've had several rb300s and a chum up the road did everything he could to improve the 300. His SME 5 blew away the rb300 and then his Teres made the SME sound rather dull. He also tried a Shroedinger which was totally numero uno but so difficult to keep set up correctly.

I was happy to settle back into the Tabriz but his journey was exciting and informative.

Since then he's gone totally Squeezebox digital front end. His preamp/ dac is home made as is his totally balanced push pull kt66 jobbie power amp into enormous Tannoys - superb!!!

My tabriz goes onto WAD phone pre into passive transformers pre into GM70 SE to (smaller) floorstanding Tannoys. I'm content.
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
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#14 Re: Roksan xerxes

Post by Daniel Quinn »

The Tabriz is full of joints held together by grub screws. It is basically a jelco . I don’t like the way the arm fits on to the base , there’s to much scope for misalignment


why they sold it for such much is beyond me
Ant
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#15 Re: Roksan xerxes

Post by Ant »

Ive got a couple of other arms to faff with, a 3009 that would require hacking the top plate so thats a no, a rega r200 that needs some wiring done that i cant be arsed to do at the moment so thats a no, and gregs mayware that would also need a longer mounting boss making to fit the top plate thickness.

Ive only got a bit of acetal big enough to make new bosses with, might have to order in some aluminium bar and make longer mounting bosses for the mayware and my arm
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