New JVC QL-Y5F.... advice on setup, mods etc...

dlaloum · « **on:** 20 Dec 2010, 06:14 am »

Hi Folks

I have been drawn to this forum by the presence of JVC oriented audiophiles....

Having been a long term Revox Linatrak user - it got stored while I went overseas, then I was busy when I got back and finally got around to pulling it out again.... was unhappy with performance and started a series of alignment checks, which led to cartridge change ... this in turn led to trying out a range of cartridges..... Which is a royal pain in the A on the Revox.... so I thought what the heck lets get a pivoted arm "sandpit"..... started with a Toshiba SR-Q630.... then got tempted by the beautiful JVC... which arrived last week.

OK these tables are fantastic lookers

- the electronics are droolworthy, as is the engineering....

but that beautiful plinth appears to be nothing but a facade

So what are people's advice with this table?

What headshells and cartridges work best in this beastie?

How easy/hard is the arm to rewire if needed?

What mods to do to the plinth to improve it?

My dustcover is distinctly yellowed - can this be cleaned or should I try to get a new one made for me?

I want to experiment with high impedance cartridge loading (60-100k) which requires low capacitance cables.... does anyone know what the capacitance of the standard JVC cables are?

Has anyone tried to re-plinth the table? (seems a shame when it is so gorgeous.... but...)

Thanks in advance...

David

TheChairGuy · « **Reply #1 on:** 20 Dec 2010, 06:31 am »

Should be some help here...the QL-Y5F is prone to some of the same feedback issues that the newer and slightly more upmarket Y66F had.

http://www.audiocircle.com/index.php?topic=63108.0

Welcome to AC!

John

dlaloum · « **Reply #2 on:** 20 Dec 2010, 06:43 am »

Thanks John,

You are the reason I am here - someone specifically mentioned you and the JVC aficionados that have gathered around you....

Do you have any idea of the capacitance of the original wiring (arm through to RCA's) of these tables?

I cannot find this information anywhere and my multimeter does not have a capacitance feature.

bye for now

David

TheChairGuy · « **Reply #3 on:** 20 Dec 2010, 04:54 pm »

David,

I don't know the capacitance for the cables on various JVC's.....I generally run Grado's and Denon DL-160vdH on them...and it makes much of the capacitance issue moot as they have very low inductance.

I know moving from the QL-A2 to the QL-F66 to the QL-Y66F (each a price jump and move towards the top of JVC offerings in each leap) had slightly thicker bundles of wire involved. So, it would seem at least anecdotally, that JVC paid some attention to lower capacitance and you moved up the chain.

If you don't already know this resource - you should - they have a library of thousands of old manuals on old TT's there: http://www.vinylengine.com/library/jvc.shtml

btw, each of the (modded) JVC's sounded better than a stock Technics SL-1200 to me. The most cost effective mod for all of them is filling the guts with as much modeling clay as they can hold without interfering with the moving parts inside. Taming the rattling plastic and faux-wood plinths is the key to getting the best from them.

Their motor/drive systems are already superlative in my book

John

dlaloum · « **Reply #4 on:** 21 Dec 2010, 11:54 pm »

Hmm before I go any further I have a hum problem to resolve....

Swapping headshells and cartridges I have a hum that comes and goes - seems to be more likely to be present with my MC cartridges (all high output) than with MM/MI.

When a headshell/cartridge is mounted hum free - it stays hum free - but swapping cartridges often results in hum.

One of my HS's is fitted with a p-mount adapter, and when I swap cartridges in the adapter the same thing happens (so far I have managed to get none of my MM/MI's working hum free!) - the p-mount Sony XL-MC104 (HO MC) seems to be OK there. The Shure, Ortofon and Stanton cause hum...

Could this be caused by a cabling problem?

Where should I start searching for the cause?

thanks

TheChairGuy · « **Reply #5 on:** 22 Dec 2010, 03:49 am »

David,

1st question....did your new deck come with a ground wire from the TT? If not, get any wire and connect the terminal on the TT to a ground post on your receiver or preamp.

Conversely, if it HAS a ground wire attached - detach it. Sometimes, that does the trick, too.

Have you ever had another TT hooked up to your MM and MC inputs previously...was there any issue ever if so?

If not, and the grounding wire has been tried connected and disconnected to no avail...you can probably conclude that there is a wiring issue either in the arm, the deck or (most likely) something to do with your headshell.

Stanton (and sister brand Pickering) tend to hum sometimes - playing the cartridge with and without the grounding strap will tell you which one works on your particular deck. I'm not aware of any peculiarities with Shure or Ortofon that would innately cause hum, however.

Hmmmmmmmm (pun clearly intended - keep your chin up - you'll muddle thru

)

John

dlaloum · « **Reply #6 on:** 22 Dec 2010, 04:14 am »

Yep has ground wire
Yep connected
Disconnecting causes vicious hum regardless of cartridge/headshell in use
System works fine (no hum) with either my Toshiba SR-Q630, or Revox B795 - and with any of the cartridges/headshells mounted.
Everything works fine with the Revox and Toshiba whether connected to the Receiver Phono stage (and receiver gnd) or Creek OBH18 phono stage (and gnd).
Same problem exists with JVC regardless of phono stage used.

The seller did make some comment about the wiring probably needing replacement .... although he did not mention hum - this may have been what he was referring to !!!

I am a Neophyte with SME / 1/2" mountings - as I have been using the Revox for the last 15+ years.... and before that I used a Pioneer with its OEM cartridge and it never occurred to me to change it (pre audiophoolia)...

I may be missing something obvious!
All my headshells have been picked up used from fleabay - I would be suspecting poor connections if it wasn't for the fact that the same headshells and cartridges were working fine in the Toshiba (a $30 pickup that tested the waters before I jumped in the deep end and went for the JVC... and now of course, I feel like I have a mouthful of seawater, and a whole bunch of large waves coming my way....and all my swimming lessons were in nice safe swimming pools)

Please make no assumptions about my experience or knowledge.... reading and theory do not make up for experience and hard knocks.... ask the ridiculous questions in case I have missed the simply too obvious to even consider!
(Turntable won't turn... is it plugged into the power? Is it on? Is the wall switch on?....)

thanks
David

dlaloum · « **Reply #7 on:** 27 Dec 2010, 04:09 pm »

Latest News...

Tested Cable capacitance (bought a meter) - at over 400pf - this is definitely NOT the original cable.

Do these JVC's use a standard Din Plug tonearm cable? (ie can I get something off the shelf) Or do I have to do some soldering /dismantling to replace the cable?

Did some more testing on the Hum - it seems to be bad connectiong related - at the arm/headshell interface - jiggling the headshell when mounting it so it made a good connection made it go away.... so I have some work to do on the contacts I would say.... (in addition to the cabling, and the plinth)

bye for now

David

P.S. - the Revox B795 Linatrack is working beautifully though.... and these two tables were in head to head comparisons when they were Top End Brand new....

Wayner · « **Reply #8 on:** 27 Dec 2010, 05:05 pm »

Get some De-oxit 5 and spray all the contacts. This will clean the metal, removing any kind of film, or smoke or whatever and give you a better contact.

AS far as the interconnects, one option would be to remove it completely and install RCA jacks to the back. Then you can use the cable of your choice. This may depend if you have the room, and that you can get at everything. Just a possible fix for the high capacitance cables.

Wayner

dlaloum · « **Reply #9 on:** 27 Dec 2010, 10:13 pm »

I'll try to track down some deoxit....

Yes, I would definitely prefer a simple set of plugs on the back rather than another captive lead....

Mt Question however is related to how it all connects up internally - does the tonearm have a standard din plug connection ?

Does the RCA out connect to a hard soldered point on one of the PCB's?

Is it (at least originally) a single piece through to the headshell mount?

Trying to work out whether this is a job for me, or one to take in to a workshop....

TheChairGuy · « **Reply #10 on:** 27 Dec 2010, 10:23 pm »

Quote from: dlaloum on 27 Dec 2010, 10:13 pm

Does the RCA out connect to a hard soldered point on one of the PCB's?

Is it (at least originally) a single piece through to the headshell mount?

Trying to work out whether this is a job for me, or one to take in to a workshop....

Thinking back to the open backs of the three JVC's I've had....I think they had one continuous run from removable headshell to a point on the PCB. From there, the wiring was the ~3' length of cable you see ending in the two rca's and ground wire.

So, upon opening up the bottom of the JVC....you may want to see if the solder points on the PCB are loose. You can de-solder the last 3' and re-solder in higher quality rca interconnects.

I find less connections are more with phono as the cartridge voltages are so tiny...when you create additional lengths of wire, solder points and rca's you're losing the vitality of the original signal along the way. So, I MUCH prefer hi-quality captive leads over rca jacks on the back of tables as it's one less solder joint and dissimilar metals for feeble cartridge voltages to hop thru.

John

dlaloum · « **Reply #11 on:** 27 Dec 2010, 11:32 pm »

I've got 7 Blue Jeans LC-1 cables on their way to me... total C of the cable should be around 60pf or less for the 1.5m length.... (Flea bay purchase of an unwanted HT interconnect set)

I would have to choose between sacrificing one of these (chopping off the end and using it in the JVC), or having RCA's fitted and doing the "standard" interconnect.

The other advantage of RCA plugs is the ability to use various cables to change my Capacitive load... Otherwise I may need more double adapters in the chain to allow for C plugs as well as I plugs.
In a perfect world this would all be built into an appropriate Phono stage... but stages that are capable of adjustability in the MM/MI area (20k to 100k impedance) and have adjustable capacitance are rarer (and more expensive) than hens teeth.

bye for now

David

dlaloum · « **Reply #12 on:** 29 Dec 2010, 02:32 pm »

Latest - Dismantled the base - took a look at the interior (took photos)

Whoever fitted that cable did not have the first idea of how to handle a soldering iron.... great hunking gobs of solder... with chunks of what may have been the original leads still in there....

Cleaned it up and repurposed a couple of inches of Cat5 UTP, to which I fitted some inline RCA sockets....

Got things reconnected and back up and running... all seems fine.

The Hum tends to come whenever I change headshells and it takes a bit of Shell Wiggling to get the connection right - whereapon it disappears. (I still have to get the Deoxit.... I was at the electronic store today and completely forgot it!)

I took a close look at the feet as well - the rubber is starting to show hints of cracking - I treated it with Rubber Renew.... but I think I need to look for alternate feet....

Does anyone know what the spec for the thread on the feet is? (or how to measure it?)

The original setup with the bell shaped vibration absorbing rubber is pretty standard - various versions of it are available made of rubber, sorbothane, and other elastomers (from various vendors).

But they don't have the appropriate chrome/metal look...

I also took several spare sorbothane pads I had lying around - enough height for them to make solid contact with the center of the plywood underpannel (and get slightly compressed).... that should dampen the wobble board a bit.

Has anyone made a new Plinth for one of these?... It doesn't look all that difficult, just requires a lot of accurate measurement.... and then precise cutting..

I would have thought there would be no problem with the top panel being twice the thickness... (all the cables look long enough for everyting to reach) - existing top is 16mm - could easily be replaced with 30mm - Densified wood (panzerholz) or bamboo laminate would be much more dampening than the original MDF.... And making the sides a bit taller, the bottom panel could be mounted on elastomer mountings to the top plinth (and also be made of a more appropriate material!)...

I am also curious as to how the Plinth was constructed for the top of the line JVC's - The 7's, 77's and 10's...?

I havn't had a chance to really listen to this beastie play yet - but I just love the way that arm works....

Provides me with the perfect platform for experimenting with cartridges/headshells etc... (The Revox is not suited to this as changing cartridges can be a difficult process)

TheChairGuy · « **Reply #13 on:** 29 Dec 2010, 06:57 pm »

Quote from: dlaloum on 29 Dec 2010, 02:32 pm

I took a close look at the feet as well - the rubber is starting to show hints of cracking - I treated it with Rubber Renew.... but I think I need to look for alternate feet....

Does anyone know what the spec for the thread on the feet is? (or how to measure it?)

The original setup with the bell shaped vibration absorbing rubber is pretty standard - various versions of it are available made of rubber, sorbothane, and other elastomers (from various vendors).

But they don't have the appropriate chrome/metal look...

I also took several spare sorbothane pads I had lying around - enough height for them to make solid contact with the center of the plywood underpannel (and get slightly compressed).... that should dampen the wobble board a bit.

Has anyone made a new Plinth for one of these?... It doesn't look all that difficult, just requires a lot of accurate measurement.... and then precise cutting..

The DD JVC's I've had, I think, all had the fairly standard M6 threads for feet. I think it's the same threads for the venerable Technics SL-1200 so upmarket replacement feet that thread in perfectly should be a-plenty out there.

The JVC feet universally stink and changing them out is a significant upgrade. I use 3.5" maple cutting boards under my tables (its the best vibration aid I've yet heard and it cost me only $100...it's generally better than any cartridge swap for $100 you can find)

Under the JVC's, I have a Herbie's (silicone) feet and under those, brass toes head down into the maple block. It provides the right coupling/decoupling and vibration absorption for me.

The wobbly bottom board on the non-plastic bodies JVC's (the plastic bodied JVC's are easier to cure of ills as they are rigid already...yet merely need damping with modeling clay internally) is horrible. I used spray damping rubber elastic compound on mine to damp it, but it still flexes...which causes a speaker cone like device to amplify feedback present in and around all TT's. There are many fixes - all not simple, unfortunately.

An entire new plinth would probably improve matters entirely....bit, I have to tell you that the QL-Y5F is a stablemate to the QL-F6 in 1979 JVC line...and the QL-F6 has much the same operation internals and has a plastic body...which can be fixed easier than the fancy plinth that the QL-Y5F is to fix.

Modelling clay intenally, a lot of it, is a great answer for many of the ills they suffer from.

The drive system and other matters of JVC was so much better than Technics....yet Technics (and Kenwood and some others at that time) did a lot more to make better, less resonant plinths.

Ciao, John

Wayner · « **Reply #14 on:** 29 Dec 2010, 10:11 pm »

Put a dot of plasticlay about 3" down from the tonearm's horizontal pivots. About 1/4" in diameter, 3/32" thick. Make sure it's secure to the tonearm. Interesting results, at least at my house.

Wayner

dlaloum · « **Reply #15 on:** 30 Dec 2010, 01:24 am »

Hi Wayner - sounds a lot like the Herbies tonearm vibration damper...

Looking at the Putty option - or doing something else at the bottom....

I noted that the bottom panel has holes in it - for ventilation? If I was to seal things off am I risking overheating?

So for example if I sprayed the bottom panel with sound dampening - I will almost certainly close those holes....

Some of the alternatives include removing the feet and placing on a rubber/foam mat - again, no ventilation.

I know that total wattage is very low (16W) -but if closed up that is plenty to cause trouble!

I also noted that the bottom panel includes a grounded metal section located just below the tonearm - part of the shielding....

Removing the bottom panel sounds like a good option but 1) I would lose that shield, and 2) the power and audio out load bearing clips are connected to it....

Removing feet and placing on foam/rubber has potential for overheating...

Wayner · « **Reply #16 on:** 30 Dec 2010, 01:04 pm »

I would not close off the holes. Ventilation is a good thing. 16 watts is lots of heat if the area is ventless. I would use some plasticlay on clay-able areas of the bottom cover, then move on. There seems to be 2 completely different directions as far as the feet go. Some folks go with the metal cones, others go for the soft and squishy approach. I like the latter, but the real answer to avoiding feedback vibration thru the feet is table location. Keeping it away from speakers and having it on a massive perch will be of the most help, IMO.

Wayner

dlaloum · « **Reply #17 on:** 7 Jan 2011, 05:19 pm »

Hi folks

the TT is running well - initial humming issues were resolved (bad connections)

Plinth is stabilised / slightly damped by having a raised sorbothane puck right in the middle of the underside of the plinth - pushing slightly upwards (a bit of compression to place the sorbothane in its optimal damping environment)

I am considering my options for the interior of the plinth .... I just hate the idea of putty..... prefer the idea of making a custom plinth of the right materials in the first place, but that is a big (huge) job.

I have temporarily rewired with some Cat5 cable coming out the back - everything working well.

Have also received delivery of some BlueJeans LC-1 Cables, 1 of which may shortly be canibalised to create a proper captive lead.

Any ideas how I can support / attach the cables at the exit point from the plinth? The standar 90 degree bend plastic thingy is both too constrained for the thickness of this cable and would impose a 90 degree bend which solid core coax won't take well to... I need to solder it in with a nice gentle curve leading out... (kinks will affect the capacitance as well as potentially breaking the solid core!) - and with something to support the cable at the exit point....

I truly love the way this things arm works - a true tech geeks delight.....
So is my other Turntable - Revox Linatrak.... but their character is like chalk and cheese - there is a delicacy to the JVC that the Studio/Semi Pro Revox doesn't have..... on the other hand the JVC does not feel built like the proverbial brick outhouse the way the Revox is.... (this is all just look and feel though, can't compare sound really until things are properly sorted)

bye for now

David

Wayner · « **Reply #18 on:** 7 Jan 2011, 06:54 pm »

If I were to manufacturer new tables, the interior would be stuffed with Plasticlay>

Wayner

TheChairGuy · « **Reply #19 on:** 7 Jan 2011, 07:35 pm »

Ditto to Wayner above....you won't see the PlastiClay and the moment you play your newly clayed table the first time, you'll smack yourself up the head for doubting it's positive effects.

On a fair majority of hollow bodies decks made of plastic, on in this case poorly constructed mdf, the effect is tremendous.

Technics (with the SL-1200 and other models ) and Kenwood (they had some composite plastic/stone tables in the 70's and 80's that were superb in construction, too) were the only two mass-scale Japanese makers that I'm aware of that really paid attention to plinth construction

Well, maybe Denon, too to a lesser extent

Sadly, JVC for all it's groundbreaking innovation in DD drive systems...a common theme letting all of them down is the feeble plinth setup. The PlastiClay mitigates a LOT of those shortcomings so that you can enjoy the oft superior drive systems these babies had

John