Assessing turntable upgrades I – VTA adjustment

Standard intro and disclaimer

High resolution digital recordings of hifi system upgrades can be used for subsequent comparison to provide a more reliable method of assessment than trying to apply and assess the update at the same time. Other benefits are the possibility of external validation of conclusions, and letting others hear the kind of changes that are possible for a given level of effort or expenditure.
It should be understood that no assessments are being made with regard to the relative performance of analogue vs high-resolution digital.

To avoid any copyright issues I’m restricting my recordings to 1 minute for vocal work, and 2 minutes for classical. My test recordings are as follows.

Female vocal, easy listening
Don’t know why – Norah Jones, Album: “come away with me”
Cold cold heart – Norah Jones, Album: “come away with me”
I’m alright – Madeleine Peyroux, Album “Half the perfect world”

Male vocal, pop
Paper walls – Marc Cohn, Album “The Rainy Season”

Classical
Schubert Symphony no.5 in B flat major, D 485, Album “Frans Schubert, Symphonien Nos. 5&6, The chamber Orchestra of Europe with Claudio Abbado”.


Test purpose
The necessity of accurate arm and cartridge alignment is widely accepted. In this test I am assessing the differences in tonal balance when the vertical tracking angle (VTA) is changed. I have assessed the differences due to approximately 1 degree of VTA change, with both values lying close to 24 degrees (it is hard to accurately measure VTA values).
The analogue front end under test was comprised of a Pink Triangle Export with Funk Firm V-drive DC motor upgrade, SME IV tonearm, Dynavector DV10x5 high output MC cartridge and Graham Slee gram amp 2 SE phono stage.

Test preparation
Before each test session, the turntable was warmed up by playing one side of an album.
The phono stage was left running for 30 minutes before the start of the test.
Recordings hve been captured as 24bit, 96kHz WAV files using a SoundBlaster X-fi PCMCIA soundcard and a Dell Inspiron laptop.

Test method
For each alignment :

  1. Measure the distance between the record surface and the centreline of the arm tube at two reference points. All measurements were taken on the same side and position on a specific LP.
  2. Measure the downforce, and adjust as necessary to ensure the same value is used for both alignments.
  3. Make the recordings listed above.
  4. After taking the recordings, calculate the relative change in the heights of the front and back of the arm tube, from which the change in VTA can be calculated.

Results
Caveat: these are high resolution recordings taken from a high performance audio system, and are intended for download. The differences are unlikely to be audible through the embedded player and typical computer speakers.

Alignment 1
front 12.5mm, rear 10.5mm
downforce 2.1g

dont know why 1-tt1
cold cold heart 1-tt1
Im allright 1-tt1
paper walls 1-tt1
Schubert-D485 1-tt1

Alignment 6 (I tried a number of others but these two give the best contrast)
front 13.5mm, rear 13.5mm
downforce 2.1g

dont know why 6-tt1
cold cold heart 6-tt1
Im allright 6-tt1
Paper walls 6-tt1
Schubert-D485 6-tt1
  1. front change in height : 1mm
  2. rear change in height : 3mm
  3. distance between measurement points = approx 100mm
    so I’d expect the angle change to be tan^-1(2/100) = 1.1 degrees, let’s say 1 degree.

Measurements from photographs agree with this calculation.

This small change in VTA produced clearly audible changes in the tonal balance of the system. The brighter sounding recordings were taken with the tonearm level, the other set with the back lower.

Conclusion
A one degree change in VTA produced clearly audible changes in the tonal balance of the system. For reference, the relative change in the positions of the front and back of the tonearm required was 2mm. This clearly indicates that careful setup and listening tests pay dividends in the overall sound from a hifi system.

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