Here's a twist. As Dougdeacon so well reminds us, each record is different and styli shapes differ, so it is somewhat futile to fixate on the 92 degrees. However, out of curiosity, I did check to see how close my SRA is to 92 deg. when my arm is horizontal. Very close. So with that for comfort and as a starting point, I adjusted further by listening to a variety of LPs until I found the setting I liked. For me it is a compromise because the VTA is difficult to set with my arm, so I don't do it for each record.
Doug explained to me once what it is that should be listened for. It is not a tonal balance between highs and lows as I had thought, but rather it is a timing issue involving the initial transient, the sustain and the decay. The relationship of each of these for a plucked note on a mandolin or harpsichord should sound natural and have the correct timing.
Rather than corrupting Doug's description any further, perhaps he could once again explain exactly what to listen for when adjusting SRA. |
Using my MINT LP arc protractor, it is very clear that changes in VTA (SRA)
alter overhang. It is more severe at the outer edge than at the inner grooves
because of the trace of the arc. IOW, the variance away from the arc is
greatest at the beginning of the LP.
In my system, this is audible. The MINT is extremely precise, assuming that it
was ordered correctly with the right pivot to stylus distance, or effective
length.
Now the Mint glass thickness is different from the various LP thicknesses, and
thus overhang changes slightly with different LP thicknesses.
Regarding the timing of the note when adjusting VTA, I think Schroeder is
talking about the harmonics not arriving before or simultaneously to the
fundamental. IOW, the note's fundamental (frequency?) should be heard first,
followed by its harmonics with a natural sounding delay. This is pretty easy
to hear with a mandolin or harpsichord pluck. If the timing of that pluck is
off, the VTA is off. I think this is his and DougDeacon's point. |
I think of it like this: If the fundamental is being obscured by the harmonics, the harmonics are arriving too early. I hear this when the arm is too low in the back. If the fundamental occurs unnaturally early, or there appears to be a minute lag before you hear the harmonics after the fundamental, then the arm is too high.
This is roughly how Doug described it to me and it corresponds to what I hear. I can see how this could be described as a tonal shift or emphasis between the high and low frequencies. |
John, I appreciate your providing the links. I enjoy such articles and do find them helpful to understand the technical issues involved and why there are limitations to the medium.
I just thought I would share some listening impressions I've had recently and how small changes to SRA can in fact alter our impression of how an LP sounds relative to hearing something real like a solo cello and orchestra during an actual concert. |
Raul, when one slides a cartridge in the headshell 0.3mm to make a very slight change in overhang because the SRA has been adjusted, how does one achieve this tiny move without rotating the cartridge about its ZENITH angle? With some stylii profiles, proper ZENITH alignment matters a lot. Of course it changes over the length of the LP and is only truly tangent at the two null points.
And, if overhang changes, does this not also require a tiny change in ZENITH so that the stylus maintains proper alignment (true tangence) at the two null points?
I did compare the alignment results between the SME protractor and my custom MINT LP arc type protractor and found that the overhang was slightly different. I can't say which is more correct, but the MINT is more accurate and allows for more precise results. I did find the music sounded better also, though this may just be that "I like it" more with the MINT.
One issue with the MINT is that the thickness of the glass is not the same as every LP thickness, so overhang is only correct with LPs that happen to be the same thickness as the glass. Overhang for other thickness LPs will necessarily be different.
If, as you contend, that overhang is more critical than SRA, what do you think about all of the people who adjust VTA for each LP without also adjusting overhang? The people with whom I have spoken feel that proper SRA is more critical than perfect overhang, so they don't bother to adjust both with each LP. Could you imagine the time involved to do both for every LP?
I'm only asking these questions to learn more about the subject. I'm very curious about how each of these adjustments effects the others and really which is the most critical. I, for one, adjust my arm and cartridge to be the best compromise with a group of my favorite and most familiar LPs. I don't have the patience to adjust settings for different LPs. |
Doug and Raul, I've been experimenting some more with the VTA on my SME V-12. I don't know if my hearing is becoming more acute, or if I'm slowly learning more about what to listen for. It is now clear to me that my VTA has been too high for my thinner, mostly classical 150 gram LPs. The newer reissues at 180 grams sounds great but on careful listening to my older, thinner LPs, the harmonics do seem to arrive a bit too early, obscuring the fundamental.
Doug is correct that I reversed the description of the arm. So I lowered the arm about 1mm and this improved the relationship between harmonics and fundamentals, just as we discussed earlier up the thread. Interestingly, to Raul's point, dynamics also improved and this was quite noticeable. There is also a fuller, richer sound to massed strings and the midrange in general as well as more ambient cues and spatial information.
I listened first to 3 thinner 150 gram LPs: Vivaldi's Concerto for two Mandolins, a solo Mozart piano recording and the Sheffield Drum Track LP. In each case the lower VTA setting improved the sound and enjoyment of the music. But when I then listened to the thicker 180 gram reissues of Muddy Waters Folk Singer, Ella and Louise and Julie London, they lacked dynamics and sounded a bit dull. So I raised the VTA and everything sounded right again.
Yesterday, I heard Shostakavich's "Cello Concerto No. 1 in E-Flat, Opus 107" with Yo Yo Ma at the BSO from the fifth row center. Being about 20 feet from Mr. Ma's incredible cello playing was quite a treat and it gave me a real sense of the energy and sound of that instrument. With the sound fresh in my mind, I went home and wanted to immediately compare the sound of that cello to some of my recordings. Since I don't have that recording I played Dvorak' Cello Concerto and Brahm's Concerto for Violin and Cello. Sure enough, altering VTA by 1mm in the back of a 12" arm was clearly audible and effected how natural the recorded cello sounded, but it also improved the sound of the rest of the orchestra and the sound of the hall.
So, I just thought I would share my experience about listening to the effect of VTA/SRA changes and move for a bit away from the technical discussion of cutter heads and cartridges. I'm now a firm believer in the importance of proper VTA/SRA settings and the need to adjust, at least slightly for different thickness LPs. I never thought I would do this with my current arm. I don't want to change for every LP like some of you do, as it is too cumbersome. SME trades convenience/ease of adjustments for a very rigid/solid anchoring of the bearing tower in the arm board. I think I will simply change between two settings for thick or thin LPs by creating a metal shim for confirming the proper height. This will make changes fairly easy and repeatable and the music will sound better. |
Ack, that may well be the case. As overhang changes, so does zenith along the tracing arc. I can see by how much at the null points on my MINT protractor. I lent out my VTF gauge, so when I get that back, I will see if it can measure a difference of 0.1 gram, for such a tiny VTA adjustment. Don't know if it will.
I'm hardly going to adjust all parameters for each LP. I'm going to settle on an overall good sounding average and decide how often I want to adjust VTA. I'm guessing it won't be too often, though I've found during the last few evenings, that adjusting VTA on my SME is not that difficult. There just is not a convenient scale marked on a tower like some other arms have.
I think these parameters vary less with a 12" arm than they would with a 9" arm, but then a 9" arm would have to move less than that 1mm for the same 1/4 degree SRA change. Admittedly, these are tiny changes and many will not find them worth the effort or sonic improvement to make.
I wonder if anyone has thought about designing an arm which would automatically compensate overhang and VTF for VTA changes. |
Smoffatt, Here is my sequence, (SME V-12 arm) realizing that others may do it slightly differently. I tried the 92 degrees with USB scope and now just start with arm horizontal and adjust VTA for favorite LPs by listening. If lazy, I just pick a good, average VTA setting.
Start with arm horizontal and anti skate at zero
VTF
Overhang (with Mint protractor)
Zenith (Mint protractor)
anti-skate
Azimuth (not adjustable on my arm)
Damping (tried it, don't need it)
Listen
VTA 2nd round fine tuning by listening to representative LP
anti skate back to zero to
reset overhang for new VTA
reset zenith due to new overhang
reset anti skate by listening
decide if re adjusting VTA for each LP is right for you.
Ready to listen and enjoy the music |
