Thomas_AA
Well-Known Member
SRA imperfection manifests as an imperfect fit in HF grooves, and is level related. I have to revisit the shimming since it gave higher HF output.
VTA method???
- Thread starter rodman101
- Start date
mr_petit
High on Vinyl
But then why didn't you go higher in turns?
You stopped at 4 turns, from which you say is about the setting when the arm is straight. You go lower (down to 0 turns) but not higher to see what happens.
And so you don't think it manifests as IMD?
I can't really see a continuous trend in your frequency/harmonic distortion plots that points to a certain setting being much better than the other one.
That method that Balle chlorin used in your first ASR example was more clear. However, not knowing how much 1 turn is on your vta knob I have a feeling that his test/test record adresses a much much larger range of vta(sra whatever...) than the turns you make on your arm. Maybe even an order of a magnitude bigger.
That was also the point I was making in the beginning. His differences are very clear, but the range of his test record is huge, way more than any normal arm height adjustment can reach in practice for most turntables.
You stopped at 4 turns, from which you say is about the setting when the arm is straight. You go lower (down to 0 turns) but not higher to see what happens.
And so you don't think it manifests as IMD?
I can't really see a continuous trend in your frequency/harmonic distortion plots that points to a certain setting being much better than the other one.
That method that Balle chlorin used in your first ASR example was more clear. However, not knowing how much 1 turn is on your vta knob I have a feeling that his test/test record adresses a much much larger range of vta(sra whatever...) than the turns you make on your arm. Maybe even an order of a magnitude bigger.
That was also the point I was making in the beginning. His differences are very clear, but the range of his test record is huge, way more than any normal arm height adjustment can reach in practice for most turntables.
Last edited:
Thomas_AA
Well-Known Member
SRA correction by arm height gives only a small compensation. Shimming is gives a larger effect. I will return looking closer at this. You can see the first shimming experiment in the same post.
If you read the link I posted before regarding VTA and SRA you can see that SRA is a separate issue and can be measured with high frequency signals, such as the carrier signal for quadraphonic discs.
Get an arm what allow enough range of adjustment
In my experience with Ortofon MC5000 (now retipped with VDH 1) and SPU Royal N (now is on the way for retipping to micro ridge + boron cantilever) - when VTA was set with test record, cartridge was parallel to record as it should. Both cartridges originally has Ortofon Replicant r/R 5/100 microns. Small radius is too big anyway, but acceptable especially for records from 60s 
. For fine tuning I reproduce inner track of particular record, use headphones and spectral display on PC. Procedure is similar like azimuth alignment on tape, except there is spectral display used instead of phase spectral display. And if azimuth is always aligned when signal is switched to mono, in this case compare both. So correct position can be seen and heard. You can clearly see and hear when upper frequencies changes. If we are talking about compromise between high frequency response and harmonic distortion - I have no my own opinion.
Thomas_AA
Well-Known Member
Well as previously mentioned, i am not fond of changing arm height for SRA/VTA. Neither does Wallyanalog. They suggest use shims.Get an arm what allow enough range of adjustment
I do not know what doing or suggesting Wallyanalog, but there is simple geometry at least from ancient Hellas, but I suspect that the Sumerians already knew this around the time of the invention of the wheel. Or for shims it does not apply?
Thomas_AA
Well-Known Member
Arm height changes other things as well as you might know.I do not know what doing or suggesting Wallyanalog, but there is simple geometry at least from ancient Hellas, but I suspect that the Sumerians already knew this around the time of the invention of the wheel. Or for shims it does not apply?
Really? It is not human reproduction organ what is more important than head. I do not know what other things arm high changes.
Thomas_AA
Well-Known Member
Warp wow is one. Centre of gravity and force vectors
Oho! Where do you learned those terms? And how they changes and affect performance? Arm/cartridge should be at right level related to record. How do tower cranes still deal with these problems? It is simple geometry how much you should rise one or another end of tonearm.
Funny, notice how the OP, @rodman101 has not been heard from since post #1? Sorry if we got a little carried away amigo, but there are a few subjects that will seemingly generate a lot of comments and this, I'm afraid, is one of those. Hope you have been following along, and besides, you did ask for comments!!! Good bunch here, just sayin'.....
Thomas_AA
Well-Known Member
Again, ideal pp is at record level which my DP-8 has. Have you ever set such an arm up and balanced the centre of gravity? Raising or lowering a few mm does not matter much but moving it cm is not a good idea. If needed I use shims.
Ilikevinyl
Cool Breeze
Micrometer VTA Adjuster on my Jelco tonearm. Makes setting correct VTA so easy. Write down on small notepad for each cartridge the VTA numbers.
You really know what center of gravity means? Can you explain how it could changes by rising or lowering arm base?
That looks really appealing, @Ilikevinyl ! Now, can you turn that and adjust the arm base height up and down while a record is playing?
Thomas_AA
Well-Known Member
(i) If you change pivot point from record level you change the vector force due to stylus drag and friction.
(Ii) warp wow gets worse (as compared to pp at average record level)
(Iii) centre of gravity vs pp does not change very much but at extremes it moves vs pp due to the arc
(Iv) there is no way changing tonearm height to compensate for the average cartridge produced today which has 6-10 degree VTA off. If it would be possible I refer to the problems mentioned above
It's fun when someone gets a bike with octagonal wheels and tries to make ovals on them instead of putting round ones on. I will not pursue this topic any further, just curios - where are you going to push those shims? If below the tonearm, how does it differ from normal height adjustment?
Thomas_AA
Well-Known Member
Shims are going between the headshell and cartridge (home-made). They are of course only put at the back causing an angle. Tonearm base position will be PP=record level.
As mentioned, when you change the height you change other things as well - if you really want to know the effect of VTA (or SRA) you should keep other things equal. Such as the vectors of the tonearm forces. I am usually not fond of linking to companies that have their own interest, but WAMs educational videos are among the better ones. VTA and SRA videos recommended.
Educational Videos - START HERE | WallyTools
WAM Engineering's essential collection of analog optimization videos
www.wallyanalog.com
You can also look at the Kuzmas pictures of COG and PP.
Articles - Kuzma Professional Turntables, Tonearms and Accessories
Professional Turntables, Tonearms and Accessories.
www.kuzma.si
Learn geometry please. It is at primary school level
Shims under cartridge are used if tonearm high is not adjustable and you need to install cartridge with lower high as reference. Or if you can not lower bottom end enough because of limited adjustment range. As I see you are totally confused. Are you from Småland
Thomas_AA
Well-Known Member
You seem not to grasp the problem. Shims are of course angled. Tonearm height changes the force vectors of the arm. Just follow my previous links.Learn geometry please. It is at primary school level
Corrective Shim - Cured Resin | WallyTools
+3 to -10 degree corrective shims available. Angular correction on the front back (SRA/VTA) axis only. Price includes top side shims (standard and Kuzma style). A negative number is in same direction as if you were to LOWER the arm height.
www.wallyanalog.com