[Wayner]

David, is that value measured thru the cartridge coils? When I make Longhorn cartridges, I always check the coil resistance, which for the Grado Gold1 should be about 440 ohms. There sometimes is a difference in value, I doubt if few cartridges are exactly the same.

Wayner 

[dlaloum]

Left measures 449ohm and right 450ohm on the grado....

The cartridge I had on the table at the time I wrote that note was a Signet TK6Ep (I think?) - 791/797

Other cartridge I have been playing recently has been the Pickering XSP3003 644/648

All of these are sufficiently close to each other to make me think the cartridge itself is an unlikely suspect...

And I strongly agree with measuring the cartridge coils... both for resistance and for inductance.

Some of the cartridges have sufficient inductance difference between the coils to account for some of the balance frequency response variations...

[e.man]

Looks like it must be 'Visit the JVC TT Crew' time,  hahaha.  As usual my comments are much less technical.

I sold my Ortofon Concorde as upthread we found it was the wrong non-adjustable overhang.
I put on a Stanton headshell w/ Stanton 680/Shibata.   After a while i wondered if i'd damaged the stylus cleaning it because there was no 'Shibata Sparkle'.
Easy way to tell was to stick it back on the other TT with the Stanton 'Sister' Pickering (MI).  Sounds fine.  What i did notice changing was that on the other TT the MI has a 'heavier' sound than the Ortofon OM 30 i had been running.
My JVC seems to have a more 'subdued' (maybe some would say 'smooth') sound than my other TT.  Maybe the 'heavier' sounding MI Stanton is not a good match ?
The short and cheaper option is to get an Ortofon OM cart. mounted up with my '30' stylus onto the JVC to see how it goes.  Still in the ideas pile is to get an MM/MC phono stage and try a Denon DL-110 which was said upthread to maybe have a lighter sound.
thanks for any comments on this.

[dlaloum]

It may be that the cartridge/arm resonance is boosting the bass and perhaps (through intermodulation) the presence region as well...

Try it again on the JVC with the Q Damping turned to Zero.....  This won't make the resonance equal between the two (arm masses will be different) - but it will allow you to hear the bits the damping removes, and work out whether you wanted those bits as euphonic (desirable) distortion.

Bye For now

David

[e.man]

Good idea.
I turned it down to 0 and after a listen dialed a bit back in.
After this and a pin-point stylus cleaning the casual listener would not hear much difference. 
I think I might just be hearing the difference between the TTs, (and carts), which is a new thing for me.

[dlaloum]

I'd hesitate at calling it the difference between the TT's....

To ass damping to a standard (undamped) arm, you can attach a straightened paper clip, with two little paddles glued to it (horizontal and vertical), have the paddles sitting in small container of oil, and the top of the clip attached to the arm.

I've seen this done off the back of the arm (clip sticky taped to counterweight) - with a long-ish trough for the oil, or in front of the pivot where the trough can be something like a jar lid....
(depends on the TT, where there is room, how long the paddle travel needs to be, etc...)

In all cases the damping will eliminate unwanted resonances and improve the sound. (well improve is subjective - it will make the sound more true to the original recording)

What you have identified is the specific colouration added to the sound by the arm resonance.... the bit that is eliminated by damping the arm. -congrats!

bye for now

David

[e.man]

Mmm  .. thanks for that, but it's getting a bit carried away for me, hahaha.

I'll keep on listening and adding changes tho.

[dlaloum]

An update for the JVC QL-Y5F mods collection....

I recently had to rewire the table.... just the Interconnects.

I had fitted BlueJeans LC1, which is both thick and inflexible, but in experimenting, it worked out that the feet that gave the best results (noise measured by placing the needle on the plinth and using an FFT RTA to analyse the noise) - were very low - and put pressure on the cables -eventually one gave way.... lost a channel.

So I took it appart to fit more flexible (higher Capacitance) cable - much shorter, so the end result is the same net capacitance, and the phono stage has been relocated to right behind the TT...

While doing this, I took the opportunity to put some more plasticine (modelling clay inside the TT), and I decided to take a look at the plastic molding that sits  under the platter, and to which both the transformer and motor are attached.

Removing this showed that the circumference was completely hollow - and given that it is attached to the transformer AND the motor another potential resonant cavity - this was promptly filled with plasticine.

All depressions on the underside of the molding were also filled with tiny amounts of plasticine before it was remounted - the unit still looks original but has an additional 400g of plasticine in it, and additional resonant cavities have been filled.

I do have some photos that I will upload shortly.

It had not occurred to me earlier to remove the plastic molding and investigate it... but I believe it is a worthwhile improvement, as it places an additional mass on top of the plinth as well as damping both the plinth and the molding directly.

I probably should at some point investigate the tonearm mounting in a similar way  - but was not game this time.

The TT is back together and making music again currently with a very sweet Dynavector DV23RS....

bye of now

David

[dlaloum]

So in Pictorial form with more info....

Here is the Plinth with the platter molding removed:








Here is the back of the molding showing the attached motor:




You can clearly see the empty space around the circumference....

Now I start to fill it:






I also fill any additional gaps, and place dots in molding depressions around the molding...








The end result is also to create small CLD (constrained layer damping) patches by having the plasticine sit between the dissimilar materials of plinth and molding, differential vibration causes shear effect with the plasticine, which converts vibrations to heat....

A further note about heat... while I am on the topic - on first opening the plinth (it had been running for some hours) - I found the motor, power circuitry and transformer to be quite warm.
The warmth had softened the plasticine that was placed in the plinth around that particular area - there is DEFINITELY a need to ensure proper ventilation.


bye for now

David

[dlaloum]

I thought I would also document what my Rack is like at this stage... and how I got it to that point...


I spent a lot of time working on my rack - preferred option would be a wall mount shelf - but as this was not an option for me...

I purchased a 60cm x 60cm concrete paver (which I treated with danish wood oil to seal it and avoid concrete dust) - My rack then stands on this paver - which 36kg mass makes it less prone to vibrations transmitted from my sprung wood floor (less of a problem if your floor is a concrete slab!). - This is sitting on top of 4 Sorbothane pucks.

I use Ikea Lack tables as the stand - they are very lightweight - but their paper box construction (with a nice wooden laminate finish) makes them very effective dampers of high frequency vibrations - while also making them perfect transmitters of low frequency vibrations.

The bottom lack table is on spikes on the concrete - so it is "connected" to the 36kg mass below.

On top of this bottom table is a set of magnetic levitation feet (Triton NeoLev) - which further Isolates the next layer - which is an Ikea Lack table top (no legs, used as a platform).

My first TT (Revox B795 Linear tracking, suspended plinth, direct drive) -sits on this platform.
Then there is a second Ikea Lack table also standing on the platform, making the second layer. - to stop any slippage, and to provide a small amount of damping, a tiny amount of plasticine was placed under each foot.
 
On top of this table, I have the JVC QL-Y5f turntable. I have removed the OEM feet, and replaced them with ISO-9H isolating supports (in a triangle/Y pattern, two at the front, one at the back and one in the centre)

I spent quite a bit of time testing and trying out various combinations to get the best result out of the JVC...

For testing, what I did was put a metal block on the plinth to raise it to needle level, then gently put the needle on the block - the needle/cartridge was now recording vibrations straight from the plinth.

I recorded this into my PC, and fed it through a Real Time Spectrum analyser, so I could see what was happening at various frequencies.

The collection of feet / isolators I own and have used during these tests include:

a) ISO-9H isolators (currently in use under the JVC TT)
b) VALAB ball bearing feet (tried, did not find a position where they where better than what I now have)
c,d,e,f,g) Sorbothane Domes (I have sets of 5 various diameters/sizes.... in the end, none of them are appropriate for my setup!) 
h) Sorbothane Pucks (round 2.5" diameter - I have them positioned under the concrete block - measurably reduced impact of low frequency noise being transmitted from floor)
i,j,k) Spikes/Cones - 3 different types/sizes
l) Audio Technica AT606 Damping feet/supports
m) Triton NeoLev magnetic levitation feet
n) Plasticine / Modelling clay
o) MicroSeiki heavy duty rubber isolating feet.

The concrete slab mounted on Sorbothane pucks was my biggest win - an immediate 10db reduction in low frequency noise!! (along with the peak resonance dropping off, the higher frequencies, and especially the midrange cleaned up, probably due to a reduction of intermodulation distortion with the LF resonance!)

I then experimented with various materials under the bottom table - Spikes proved to be the best here.

My next win was the levitation feet - it appears that the only solution to the floor borne vibrations was complete isolation - the slab and sorbothane pucks helped a lot, the MagLev feet sorted it out nicely.

Once that was done I had the top two layers and both turntables now sitting on an isolated surface - but the next issue is dissipating/damping/absorbing any vibration generated by either feedback, or by the turntable mechanicals (including the stylus!) themselves.

The tables I use as base are good at controlling higher frequencies due to their internal construction and bracing.... but I still noted some low frequency peaks and their harmonics on the spectral scans (main peak was well below 20Hz - but harmonics were extending to around 300Hz visibly.... - level was very low, and not directly audible as "noise" - but visible using the measurement method, and reducing the noise cleaned up the sound.... made the system more detailed.... or rather allowed the micro-detail in the recording to be heard).

The plasticine between platform and top table had no visible impact one way or the other, as compared to no interface material. But the result was better than spikes, sorbothane domes, sorbothane pucks.... etc.... (having the table directly on the other table was too slippery to be safe for daily use.... - but with a thin plasticine layer it works excellently - it may also be providing some damping at frequencies I was not measuring )

The feet for the JVC table itself have their own dampers built in, but the bottom panel of the plinth tended to vibrate - causing problems....
My solution to this:
1) Insert cardboard rolls (toilet roll cores) between top of plinth and baseboard, filled with plasticine - providing a damped "spring" between the two surfaces - this helped a lot
2) The problem was still that the center would resonate, I need to connect the center of the baseboard to the platform on which it sits, thereby connecting platform to baseboard to upper plinth surface via the internal plasticine/rolls and the foot underneath.
3) A foot on each corner is nice and stable, but it tended to vibrate - the triangle pattern was more stable - two at the front and one at the rear (plus central vibration control foot)
4) All my available feet options were trialled in turn under the table, and measured - the ISO-9H proved to be the best solution with the lowest resonance levels.


End result is as follows:

  == JVC TT ===
  V ISO-9H feet V
====== Lack Table======
I                                    I
I                                    I
o very thin layer plasticine o
     Revox TT (suspended)
====== PLATFORM ======
v  Triton NeoLev feet        v
====== Lack Table======
I                                    I
I                                    I
V small tall spikes             V
====== concrete slab ====
V  sorbothane pucks         V

My next set of mods appear to be focusing on tonearm or tonearm/headshell resonances....

bye for now

David

[MaxCast]

Wow, David, that was quite the exercise. 
How big was the block of metal you put the needle on?
How about a pic of your rack sandwich 

[dlaloum]

The block was one of my spare counterweights - very handy it was too!!

I'll try and get some pics and post them up...

[mauroj]

I am loving this thread so much, I wish it hadn't tapered off. I have a QL-F6 and I have found a wealth of info in this topic. Please try to get this going again. There must be more that has been done with these tables in the last year. Thanks guys.

[jayparadigm]

I am loving this thread so much, I wish it hadn't tapered off. I have a QL-F6 and I have found a wealth of info in this topic. Please try to get this going again. There must be more that has been done with these tables in the last year. Thanks guys.

I just picked up a QL-Y5F a few weeks ago for the tidy sum of $100 from a pawnshop here in Kelowna. It looked terrible sitting there covered in dust and neglected. I brought it home and installed a new Grado Green after cleaning it up a bit and it sounds great. Now its time for tweaking. The plasticine idea is great and this coming weekend I plan to go shopping for some.
Im not entirely understanding a few things as I have only been listening to vinyl for just over a year now. I dont understand tonearm and cartridge compliance. What is it and how do I match the two ? Q adjustment ? Im not entirely getting that one either....

Jason

[neobop]

I just picked up a QL-Y5F a few weeks ago for the tidy sum of $100 from a pawnshop here in Kelowna. It looked terrible sitting there covered in dust and neglected. I brought it home and installed a new Grado Green after cleaning it up a bit and it sounds great. Now its time for tweaking. The plasticine idea is great and this coming weekend I plan to go shopping for some.
Im not entirely understanding a few things as I have only been listening to vinyl for just over a year now. I dont understand tonearm and cartridge compliance. What is it and how do I match the two ? Q adjustment ? Im not entirely getting that one either....

Jason

Hi Jason, welcome to the monkey house, home of vinyl insanity nirvana.

Compliance is a measure of springiness of the cartridge suspension.  It is measured in cu - compliance units, taken at a standard frequency which is 10Hz.  In general, the higher (springer) the compliance is, the lighter (lower effective mass) the arm should be and usually the lower the vertical tracking force (VTF) is. 
Many Japanese cartridge manufacturers measure cu at 100Hz and these figures for cu must be interpolated.

The combination of cu and eff arm mass results in a low frequency resonance.  It is recommended that this resonance should be between 8 to 12Hz.  This can be estimated by calculation, but there are really no hard and fast rules for a successful combination except for extreme mismatches.  Below 6Hz or so, resonance might coincide with record warp frequencies and increase mistracking/distortion.  This is the result of a high cu cart and a heavy arm.  A low cu cart and a light arm can result in a high resonant frequency that approaches the audible band (another no-no).   

Q damping is a feature on some arms that mitigates the resultant low frequency resonance of the arm/cart combination.  The damping reduces the amplitude of this resonance.  This is a nice feature that can help the arm/cart combination that isn't ideal or reduce resonance amplitude in a good combination.  Too much Q damping results in sluggish response and an overall dull sound so it should be applied judiciously.
neo

[dlaloum]

Hi Jason,

welcome to the madhouse... (they're coming to take me away haha, to the funny farm, where things are beautiful all the time, and I'll be glad to see those men in their big white coats.... )

I just picked up a QL-Y5F a few weeks ago for the tidy sum of $100 from a pawnshop here in Kelowna. It looked terrible sitting there covered in dust and neglected. I brought it home and installed a new Grado Green after cleaning it up a bit and it sounds great. Now its time for tweaking. The plasticine idea is great and this coming weekend I plan to go shopping for some.
Im not entirely understanding a few things as I have only been listening to vinyl for just over a year now. I dont understand tonearm and cartridge compliance. What is it and how do I match the two ? Q adjustment ? Im not entirely getting that one either....

A very lucky find that TT - my one cost me 5 times that amount!

To understand tonearm / cartridge compliance, the easiest example is to imaging a car with soft springs, vs a car with very tight/hard springs...

If the cars mass is well matched to the softness/hardness of the springs, then when it hits a bump, the wheels will rise up, the motion will be absorbed by the springs and the body of the car will continue with no vertical motion (or minimal)....

Keep the same springs and use a heavier car, and when it hits a bump, the wheels rise up, the springs compress and hit the bump stops, there is a "crunch" and things get nasty for the passengers.

Same springs and a lighter car, the springs simply do not compress and absorb the bump, the body follows the bump and the whole car goes up and down with the corrugation in the road... the suspension is not doing much of anything!

Now think about the wheels and their contact with the ground....

In the perfectly matched scenario - all the motion is within the springs, the wheels stay in touch with the ground, the car continues on its way with maximum composure - just what suspension is supposed to do.

Heavier car with same springs, once they compress fully and hit the bump stops, the car is effectively unsuspended, and literally bounces across the bumps, losing traction with each bump (body goes up, springs decompress, but cannot make up for the fact that the body is now going up, so the wheels rise and lose contact with the ground).

Lighter car with same springs - the springs don't fully absorb the motion, so the body rises (same issue as when the body hits the bumpstops on the heavy car!) - again loss of tyre contact with the ground - loss of traction, roadholding, braking, etc...

Moving back to records...

Car body is the arm (heavier / lighter)
Springs are the rubber doughnut supporting the cantilever
Tyres/Wheels are the cantilever and needle
Road is the groove you are trying to track...

A perfectly matched arm mass/cartridge compliance, handles unsettling vibrations with aplomb - mismatched combinations, lose traction, and therefore "mistrack" - and in worst cases even jump....

Now lets talk about damping - even the ideal combination, still has to follow the "laws of nature" - particularly conservation of energy... the energy of the rising tyre/wheel does in fact get transferred to the cars body (arm) - but in the process of that transmission via the springing (and "shock absorbers") the energy is delayed and spread out over time - what actually happens is the frequency of the incoming energy is altered, and rather than having a short sharp peak, you end up with a much wider/broader and much shallower peak... the car body still rises and falls, but does so slowly... the motion is damped.

The maths behind all this uses terms like Q - and there are lots of references out there for spring/vibration behaviour, damping etc....

For our purposes lets just say that we can actually put in place mechanisms to absorb some of the excess energy - in the case of the QL-Y5F, a circuit senses the deflection of the arm, and applies corrective force (via electro magnets) to "damp" the motion.(Other systems use viscous fluids to resist motion and provide damping)
The downside of this, is that the damping is never perfectly in time with the music - and so will itself cause various types of much more subtle distortions, by dint of the fact that the arm is in motion. The compromise here is a tradeoff of very nasty audible and undesirable distortion, for relatively subtle and benign distortions.

In a perfect world, there would be perfectly flat records, and the turntable platform would have infinite mass and be immovable and unaffected by any vibration (so no external vibration would impinge on things..) The arm would allways remain the perfect distance from the record (and be fixed at that distance) - and the needle would require no suspension.....

Unfortunately this is not the case, and the rotation of the record itself introduces vibrations, vinyl is an imperfect medium which adds its own "bumps" (even when very good quality...), and no turntable is fully isolated from the outside world and its vibrations - the arm/cartridge has to negotiate this imperfect world .... and hence suspension and damping!

On mere "ordinary" arms, there is damping introduced by bearing friction and the viscosity of the oils used on the arm bearings... In a normal cartridge, the rubber doughnut holding the cantilever provides not only springing, but also damping.... - Which is why ordinary arms and cartridges work!

Better arms frequently have specifically designed damping systems - like the electro magnetic one in the JVC's, Denon's, Sony Biotracers, etc... - or fluid dampers using oil in various forms, quite common on the better "Normal" arms.

Practically speaking we accept the inevitable (which is that any sprung system has a resonant frequency!) - and we try and "aim" the resonance at a frequency where it does the least possible damage.... somewhere around 10Hz is usually good for a record player....
Then we may also apply a judiciously controlled amount of damping to further control the motion generated by that resonance.
The closer the resonance is to that 10Hz zone, the less damping we need - and therefore the less we need to risk the compromises introduced by damping.... a little damping goes a long way!

When the cartridge/arm are mismatched, we need to apply more damping, as the resonance moves to frequencies where it starts to have noticeable audible impact... so we have to get a bit more "controlling" with the damping.

The charm of a setup like the JVC, is that through the us of the electro damping (the Q dial) you can run cartridges that under other conditions are simply not a good match for an arm of this mass (it is a mid-mass arm).
A prime example is the grado cartridge you are running....

Turn the Q damping down to Zero, and you will be able to see the grado start to do the "grado dance" - don't leave it too long as it may damage the groove! - This is a very good example of what happens without damping!
It so happens that Grado's by design, have very little damping built into their suspension, and are therefore even more sensitive than most to arm mismatches.... and the JVC arm is in fact too heavy for the Grado... but with the damping applied (Q on) the results with a Grado cartridge can be phernomenal! (I sometimes run a Grado Gold on it)

You can go much more extreme than the Grado, and run very high compliance designs like the ADC XLM series - my SuperXLM has a compliance of 40cu (the Grado is around 22cu) - and yet it works beautifully in the JVC arm, due to the electro damping - quite a magical effect really.

OK I think I have waffled on long enough - sitting here with a baby that would not go to sleep.... I am perhaps less focused than I should be.... may have to edit / clarify later on

bye for now

David

[TheChairGuy]

I just picked up a QL-Y5F a few weeks ago for the tidy sum of $100 from a pawnshop here in Kelowna. It looked terrible sitting there covered in dust and neglected. I brought it home and installed a new Grado Green after cleaning it up a bit and it sounds great. Now its time for tweaking. The plasticine idea is great and this coming weekend I plan to go shopping for some.
Im not entirely understanding a few things as I have only been listening to vinyl for just over a year now. I dont understand tonearm and cartridge compliance. What is it and how do I match the two ? Q adjustment ? Im not entirely getting that one either....

Jason

Jason,

Welcome.  It's a fine series of tables from JVC....but plagued with some feedback issues.  Mounting it effectively in a spot that isolates and allows for drainage of the 'energy' stored within it is key to getting the best out of of. 

You'll see earlier in the topic the somewhat elaborate lengths I went thru to reduce feedback to bare minimum on the (similar series) JVC QL-Y66F.  Afraid that the plinth is so flimsy and there are so many doo-dads inside related to it's fully automatic basis, one can never fully vanquish the feedback issue.  The Y5F may be different, I realize, in ways that matters.

The plasticene modelling clay will help...but, unlike many other tables where not much more than that is needed to greatly improve sound with mdf sides, top and bottom...this one till test your limits of patience a bit.  Take a deep breathe and plunge in as results are worth it when you dial it in right.

Cheers, John

[jayparadigm]

Thank you to all for your information. I will draw from all of this in order to get the most out of my TT. I am wondering about tracking weight though. With my cartridge and tonearm combination being a less than ideal match, should I be looking at a lighter tracking weight ? I currently track at 1.75g and have my Q at the same setting. And as far as the Q goes, is setting it low a good reference point and adjusting it from there.

Jason

[neobop]

I am loving this thread so much, I wish it hadn't tapered off. I have a QL-F6 and I have found a wealth of info in this topic. Please try to get this going again. There must be more that has been done with these tables in the last year. Thanks guys.

Hi, and welcome to the vinyl circle, stepladder to audio ecstasy.
Your wish is our command, for now.  Threads die out when there's nothing more to say or nobody can think of anything else. 

Wasn't that a great explanation by David, of compliance?  Any questions?
Make yourself comfy and don't hesitate to ask.  The only dumb question is one not asked.
neo

[dlaloum]

Thank you to all for your information. I will draw from all of this in order to get the most out of my TT. I am wondering about tracking weight though. With my cartridge and tonearm combination being a less than ideal match, should I be looking at a lighter tracking weight ? I currently track at 1.75g and have my Q at the same setting. And as far as the Q goes, is setting it low a good reference point and adjusting it from there.

Jason

Hi Jason,

I've been running my Grado Gold1 at 1.7g and Q at around 1.5 - if you turn Q off it will start to dance quite noticeably!!! (a frightening thing!) - but I figure a touch less damping is often a good thing, and it sounds good and tracks stably like that.

Luckydog on VE did publish some spreadsheets showing how to measure and calculate optimum damping for an arm/cartridge.... but I have not had the time/inclination to  go down that path towards theoretical perfection.... so at this stage, I usually use the JVC guideline of matching VTF, and then try reducing it a bit - I never reduce it below 50% of the recommended Q... (the exception is when I am trying to measure the resonant frequency)

Hope that helps

bye for now

David