Experiments with VTF

atleast in this one, there is space for humans and equipment

For the record, it would take a 1,000W bulb to keep most cartridges warm in Ndoshi's listening room.

I presume that's why he uses a Koetsu. ;-)

for the heating bulb, you should get started right away by increasing the voltage by .1v, allowing for thermal stabilisation, I'll hope to hear from you guys in a couple of years :-)
Sorry, it was irresistable
I want to add my experiences of the last week where I can confirm that differences of .05 gm make a valid, repeatable difference. I was not able to repeat anything lighter. I checked alignment before and after the adjustment process and it was spot on. The difference from where I started and ended was .2gm lighter than recommended
in doing this I was able to lower vta to where the sra should theoretically be correct and the overall results were very satisfying.
my .02 (gm!)

Doug,

"I'm gonna design a tonearm with a built in heating coil and a thermostat. Should sound great!"

That's exactly what I saw!! Well, it was a tiny little incandescent lamp in a little 'witch's hat' reflector on a little goosneck and it's designed to heat the cart while the arm's in the rest.

You know, come to think of it, the Littlite would be perfect! Too bad about Paul -- score one for 'intelligent design'!

Do you make adjustments to VTF independent of VTA?

Yes. I agree with everything Aoliviero and Nsgarch wrote about that. The VTF tuning we're discussing is so small there's little practical effect on VTA (SRA, actually, as NSgarch said). Nor are the sonic changes from VTF fine-tuning at all similar to those of SRA fine-tuning. These adjustments sound very different.

Do you think that the differences you note are due to the change in the force the stylus is applying to the groove or to effective changes in VTA (which must change with VTF changes)?

No and no.

IMO the diffenences are due to the pressure that VTF applies to the cantilever/suspension interface. This is why excess VTF sounds so much like excess antiskating, as I mentioned above. They both apply too much external pressure and inhibit cantilever freedom.

The more pressure on the cantilever, the less free it is to respond. Its response to groove modulations will be slower and its peak amplitudes will be physically contstrained. The sonic result is smothered HF's and smothered dynamics and a general dullness or lifelessness.

OTOH, if VTF is too low, the arm and cartridge have insufficient inertia to resist moving when really big and slow transients (aka, bass notes) come along.
If the arm moves then some of the energy that should have deflected the cantilever relative to the magnets, doesn't. Result: softer bass with lower amplitudes.

Now where did I put that cartridge warming lamp? I actually suggested we use our Littlelite for that during winter months Neil, but Paul vetoed it for some reason. Oh well, another great tweak lost forever! I'm gonna design a tonearm with a built in heating coil and a thermostat. Should sound great!

MIT beat it into me ;--) Everyone knows how hard it is to get into MIT, but only graduates know how hard it is to GET OUT OF MIT !

"I just discovered a little cartridge conditioning tweak..."

Neil,you REALLY have to have a Holiday,named after you!How do you come up with this stuff?I love it!!
Even my schnorra pal's could not be "that" creative,and it is SO obviously well thought out!!!
Best!

Newbee, I think folks are unnecessarily concerned about VTF creating significant changes in SRA or VTA. With today's stiffer suspensions and shorter cantilevers, it would take a really large increase in VTF to signficantly compress/deform today's stiff suspensions with the short lever arm of today's cantilevers. I'm so old I can remember watching a Shure cantilever slowly compress into the cartridge body when too much stylus force was applied! Betcha can't do that with a contemporary MC, even at 4 grams!

I also put WAY more stock in setting SRA correctly. One can just forget about the rather nebulous, and really theoretical issue of VTA. I say 'nebulous' because with the many different cantilever lengths, what do you think is the liklihood that the one on your cartridge will match the mechanics of a cutting head? Answer: very remote! And yet that would be the ONLY situation where a match would be possible, if indeed it would matter at all.

That's why I started the thread detailing the (rather tedious) procedure of finding zero SRA for your own stylus. And if it's done using the mid-range of recommended VTF for your cartridge, no amount of future VTF tweaking within that range is going to change your SRA setting to any significant degree (that's a pun, get it? ;--)

BTW, I just discovered a little cartridge conditioning tweak that extends (as opposed to 'increases') the compliance of the suspension: once in awhile, play a SQ quadraphonic record. Their grooves add a left/right twisting motion and you'll like the improved resolution you can hear on your regular LP's. The quadraphonic pressing itself will sound crummy -- just leave the room ;--)
.

Newbee,

In trials, I did not compensate SRA when changing VTF. It would be difficult to do this precisely. As well, I always thought that changes to VTF were more pronounced than large changes in SRA. I agree that azimuth has a big impact as well. Unfortunetly with my arm, it's difficult to make changes in azimuth in a measureable way. Do you know if the Graham offers this option?

Do you make adjustments to VTF independent of VTA? Do you think that the differences you note are due to the change in the force the stylus is applying to the groove or to effective changes in VTA (which must change with VTF changes)?

I always thought it was the alignment of the stylus/groove wall contact that had the greastest impact on sound. FWIW.

Folks,

Couple more things:

1) Material with piano is very good and included in my Norah Jobnes. this seems to be a good indication of timbre.

2) There is no ultimate "perfect" setting. As you get close to optimum, you'll need to make tradeoffs between upper end extension and bass response.

Gregm,

I started with an SRA of about +1.5 degrees. A parallel tonearm with the Orpheus provides about 1.2 degree SRA.

Doug,

Good to hear about your method. I had a little difficulty trying to figure out the mistracking point. I don't know if this would be close to the minimum recommended value. Anyway, with my cartridge, I think i'm higher than 0.04 grams above mistracking. this range would probably be higher for higher compliance cartridges.

Andrew

I do as Doug suggests: Start heavy and work towards lighter. BTW Doug, someone actually makes a "cartridge warming lamp." I assumed you already had one ;--) If I can I'll find the manufacturer for you. N.
.

Andrew,

Great post. Your VTF protocol is very similar to mine, as is your description of what to listen for.

Every MC I've used has responded well to this approach:

1. Set antiskating at or near zero. Excess antiskating will interfere with the VTF optimizing process.

2. Starting from a VTF that's known to be sufficient for clean tracking, reduce VTF in ~.05g increments until HF's begin to go fuzzy and/or audible mistracking "buzz" occurs on dynamic peaks. That "mistracking point" is your benchmark, and it changes with the weather.

3. From the mistracking point, increase VTF in .01-.02g increments. Listen for just the things you described, a filling in of midrange and upper bass weight without loss of HF speed, extension and "air". Go too far and you'll lose highs and microdynamics.

Most cartridges have a very narrow VTF sweet zone that balances heft vs. finesse. On my TriPlanar/UNIverse it's .02g wide or less, and never more than .04g above the mistracking point. Other cartridges have acted similarly, though not always with such precision.

4. Nudge antiskating back up in microscopic increments, using just enough to prevent R channel mistracking on very difficult passages. Excess antiskating produces sonic mud and slowness that sound quite similar to excess VTF.

Finding a cartridge's mistracking point and moving upward from there in tiny increments is a fast, repeatable and reliable method for dialing in VTF.

Best,
Doug

P.S. The VTF sweet zone can change during a session if you're playing alot of high energy music, especially if the cartridge was cold to begin with. As the suspension warms up, the optimal VTF goes down.

I've even had optimal VTF go back up during a break, since that allowed the cartridge to cool down again. This happened during Raul's visit. We stopped playing for about an hour to have dinner. When we came back the bass was weak. I replaced a thick O-ring with a thin one, adding about .02g, and everything was fine again.

Anyone for set and forget? ;-)

Where did you set the VTA when you started? Default parallel?