Calling all REVOX Linatrack users!

[Pio1980]

I am resolving some rather severe alignment issues with a B795 and need to see as many other examples of different model versions as practical, including the later 200 series and the earlier B790, to get an idea of what is happening. Specifically I need a least one and preferable two views of the end piece of the gantry with it's reflection in the record as per the example pix.
Thanx in advance!

 

[flavio81]

I am resolving some rather severe alignment issues with a B795 and need to see as many other examples of different model versions as practical, including the later 200 series and the earlier B790, to get an idea of what is happening. Specifically I need a least one and preferable two views of the end piece of the gantry with it's reflection in the record as per the example pix.
Thanx in advance!

The manuals are up on the VinylEngine forum. We have a Revox B790 thread here, you may want to make a search.

Curiously, i have the option to buy one of those last week, but i passed.

 

[diamondsouled]

The manuals are up on the VinylEngine forum. We have a Revox B790 thread here, you may want to make a search.

Curiously, i have the option to buy one of those last week, but i passed.

I've printed off that manual and am thankful I haven't had to use it yet. You almost need to be a rocket scientist to make hide nor hair of it.

 

[Pio1980]

I do have the manuals and ca 2& 1/2 decades experience with a similar but fully-adjustable gantry set-up on a Souther arm, so setting it up is not a problem for me. What I'm looking for is evidence of gradual dish warping of the suspended baseplate due to the constant weight of the platter on the spindle motor. I had to do a considerable amount of re-shimming of the motor and platter to correct for it on my TT and am curious to see if this generally occurs otherwise undetected. Ideally the endpiece of the gantry should be perfectly in line with it's reflection in a perfectly flat record if correctly set up as per factory spec. It is the (re)shimming of the motor that both levels the platter and sets the relative distance relative to the carriage rails.

 

[radkrisdoc]

Dishwarping of any piece of plastic that is half an inch thick will happen when it is suspended between two rigid surfaces, with one surface in the center on one side (the platter) and the other surface making contact only with the periphery of the other side (four springs).

In this case though, the baseplate has always been suspended on springs. I am not sure if the springs are strong enough (or rigid?) to warp the baseplate, even considering the fact that the platter is heavy. The baseplate is definitely not poorly constructed by any means. I think it is an alignment issue that I was not aware of.

As for the pics, are you looking for an exact straight image on the record? If so, can you please see what happens without the mat?

The correct distance is 41 mm from the carriage to the platter without the mat according to the 295 manual; I adjusted the height of the needle relative to the inner groove of the mat like the 795 manual says and it worked out fine.

 

[jt45]

Couple of pics of the 790. I dont know if they will help any I dont have this table anymore. https://picasaweb.google.com/100432993815858475506/PCAudio#5611915827910228018
https://picasaweb.google.com/100432993815858475506/PCAudio#5585814625234154114

 

[Pio1980]

Dishwarping of any piece of plastic that is half an inch thick will happen when it is suspended between two rigid surfaces, with one surface in the center on one side (the platter) and the other surface making contact only with the periphery of the other side (four springs).

In this case though, the baseplate has always been suspended on springs. I am not sure if the springs are strong enough (or rigid?) to warp the baseplate, even considering the fact that the platter is heavy. The baseplate is definitely not poorly constructed by any means. I think it is an alignment issue that I was not aware of.

As for the pics, are you looking for an exact straight image on the record? If so, can you please see what happens without the mat?

The correct distance is 41 mm from the carriage to the platter without the mat according to the 295 manual; I adjusted the height of the needle relative to the inner groove of the mat like the 795 manual says and it worked out fine.

While that was for the inner groove the outer groove higth would have been much greater due to the relative platter tilt, affecting both tangency and VTA consistency. Ideally, the top of the gantry and the rails should be perfectly parallel to the plane of the platter with the distance at either end of the rails at 41mm per manual as a starting point for making adjustments. If you look at my pix you can see that the gantry tilts down-inward and the platter motor plate has been comp'ed by providing a re-shimmed tilt for the platter to correct overall parallelism. The rotor was also shimmed under the platter to raise it to correct for the slight reduction of higth due to the baseplate center's relative subsidence.
As this one came out spot-on tracking a radial line with a protractor the same thickness of an LP after correction, no further adjustments were required.

 

[Pio1980]

Couple of pics of the 790. I dont know if they will help any I dont have this table anymore. https://picasaweb.google.com/100432993815858475506/PCAudio#5611915827910228018
https://picasaweb.google.com/100432993815858475506/PCAudio#5585814625234154114

Yes it does help, thank you. From what I can extrapolate from this pic no apparent warpage occurred with your 790, which I believe uses an light metal alloy baseplate rather than the low-resonance composite of the later versions.

 

[Pio1980]

The manuals are up on the VinylEngine forum. We have a Revox B790 thread here, you may want to make a search.

Curiously, i have the option to buy one of those last week, but i passed.

I still cannot re-register with TVE but fortunately have the necessary relevant manuals.
The Linatrack pleasantly and unexpectedly surprizes me with it's micro-detailing, involving musicality, and liveliness with a cart I formerly considered OK but not "audiophile", the $20 e-Bay Digitrac 200 NE 'P' mount. If it only sounded anywhere this good in the Technics SL-7---.

 

[dlaloum]

Interesting!

I believe you have one of the "tombstone" 200NE styli, which appears to imply that it is in fact a 300SE.

The 300SE has a compliance of 35cu - making the SL7 arm too heavy for a perfect match.

The Revox arm at 4g is almost half the effective mass of the SL7 (which I believe is circa 7g?)

And just to add cream to that cake the Revox has some degree of damping at the unipivot (the grease) as well as magnetic stabilisation/damping...

Theory says it should be better - but it is always nice to hear the difference in practice! :thmbsp:

I believe most T4P cartridges are around 20cu...

The AT155LC (1/2" mount) was around 30cu, the T4P equivalent AT152LP was (is) around 20cu...

The p-mount adapter shifts the arm mass somewhat closer to the slightly heavier requirements of the p-mount system, but it is still lighter than what most p-mounts do best at... however, the damping compensates...

Shure with brush definitely does better than Shure without brush by the way... so a bit more damping helps. (this is using the SAS stylus - 22cu, as opposed to the originals which are 27cu to 35cu)

bye for now

David

p.s. have to see whether I have appropriate photos of the linatrack or whether I need to take some more...

 

[Pio1980]

Thnx David, good stuff!
I'll stick a fencepost stylus on the SL-7 and save the tombstones for the Linatrack then.
Will be interested in what you find on your Linatracks re alignment shifting.
BTW, Dale hasn't posted TVE since ca June, he come hereabouts?

 

[dlaloum]

Yes Dale does post here... I came across his posts here before the ones on VE...

 

[jim249]

B790 Pics

Here are some pics pf my B790, restored with lots of help from fellow AKr's!

 

[Pio1980]

Here are some pics pf my B790, restored with lots of help from fellow AKr's!

This B790 looks good to me, no alignment drift that I can see tho' it has been restored. Thnx!

 

[jim249]

no alignment drift that I can see tho' it has been restored

The restoration was just the electronic component updates. I am still trying to figure out the drift you are talking about.

 

[radkrisdoc]

Hi Steve

Just a thought. Have you checked the tonearm mount to see if it has come loose during its travel from IL to AL? It might still be working okay and not developed play as it is spring loaded, but if it was loose then the arm carriage will droop in.

Short of taking a laser level to the baseplate, its hard to tell if it is warped. I am surprised that this was not obvious to me.

This was one of the pics I had taken when I put the TT up for sale and I cannot tell looking at this pic for certain if there was any issue from it.

Please also check out the other pics I have in my picasa album and mainly the video there to see if this was present before it reached Alabama.

https://picasaweb.google.com/104030077253026574176/Revox#5666574462527978434

 

[Pio1980]

The restoration was just the electronic component updates. I am still trying to figure out the drift you are talking about.

It would be caused by a downward bowing of the suspended baseplate, tilting the upper components inward down. It appears it doesn't occur on the 790 with it's metal baseplate and 1kg lighter platter. The later ones have a much heavier platter and composite baseplate.

 

[Pio1980]

Hi Steve

Just a thought. Have you checked the tonearm mount to see if it has come loose during its travel from IL to AL? It might still be working okay and not developed play as it is spring loaded, but if it was loose then the arm carriage will droop in.

Short of taking a laser level to the baseplate, its hard to tell if it is warped. I am surprised that this was not obvious to me.

This was one of the pics I had taken when I put the TT up for sale and I cannot tell looking at this pic for certain if there was any issue from it.

Please also check out the other pics I have in my picasa album and mainly the video there to see if this was present before it reached Alabama.

https://picasaweb.google.com/104030077253026574176/Revox#5666574462527978434

It was apparent to me something was off when I looked at it particularly with the dust cover in place while playing, I am cursed with a very critical eye regarding geometry. The arm gantry was the first thing I checked and it was secure and absolutely level with that portion of the baseplate, so no issues there. The gantry pillar base is not adjustable for verticality in any way outside of lop-sided shimming which would have been an inadvisable and inappropriate approach. I'm certain no shipping damage of any sort occurred after confirming the trueness of the pillar to it's portion of the baseplate.
In this photo from your album you can see that the baseplate has a slight smooth downward curve relative to the lower base rim, centered at the heaviest portion of the platter/motor combo. The error is much more apparent in a reflection of the gantry endpiece relative to the it's reflection and can be seen during play as a downward tilt of the gantry itself relative to the platter bearing a record. it's definitely there and probably irremediable short of a heated press and an attached rigid support plate. Fortunately it can be corrected in this example but I don't know if it happens to all composite models or if it continues as long as the platter remains in place. If the suspension was defeated by removing the 4 spring units and permanently bolting the baseplate down on the lower portion at the shipping bosses then the progress of depression would probably be arrested, tho' I'd also probably put a bumper foot under the portion between the bosses to support that part of the underside on the table. I like the isolation the suspension provides, it seems to be effective. So I'd be loath to alter it as-is. Regardless, this project is still a work in progress.

 

[radkrisdoc]

To me it looks like the right hand side is higher than the left, as I had not fully leveled the springs as I knew I was going to pack it up anyway. Maybe Revox foresaw this issue and designed it so the motor could be shimmed.

When I had the TT I had major modification plans for it which of course never happened. One of them included separating the tonearm and the motor in two separate mounts; maybe you could think about modifying the table, which will likely upgrade it to a whole new level. There's an Empire diecast baseplate on the bay right now....

OTOH, please do pm me and let me know if you really are satisfied with the purchase. I will work with you to resolve any issues you have.

 

[dlaloum]

Is that the Empire modded Revox baseplate?

If so could you provide a link!?