Can you make a silk purse out of a sow’s ear?
From the cartridges I plotted, I came to the conclusion that the frequency response is set by the design of the coils and pole pieces while the quality of the sound is from the design of the stylus assembly (I could be wrong). My next experiment is to see if I can upgrade a QLM cartridge to an XLM by using the XLM stylus with the QLM body. Since the inductance/resistance of the coils are the same for both cartridges, I’m assuming that the internal components of the two models are the same and the difference between them is in the stylus assembly.
If the ADC QLM and XLM series have the same internal coils and pole pieces, the differences in the FR curves should only be due to the difference in the stylus assemblies. The FR curve of a QLM cartridge with an XLM stylus should be similar to an original XLM cartridge.
What a surprise. There are differences in the FR curves of the XLM and QLM models (mainly in the low frequencies) but that shape remains the same regardless of what stylus is used. So, again it appears the stylus assembly has little impact on the shape of the FR curve. But, even if the coil resistance/inductance is the same, there is something in the QLM coil design that is different from the XLM. The QLM is the budget version of the XLM series so either lower-cost versions or out-of-tolerance coils were used.
Curve of the original QLM: The low frequency curve is rather bumpy but it does smooth out over the rest of the curve.
QLM using the XLM III stylus: The XLM stylus did not smooth out the low frequency portion of the curve.
Curve of the original XLMIII: No bumps or peaks; very smooth over the entire frequency range
With the QLM36III stylus: Some small bumps but overall, smoother compared to the original QLM curve.
From the cartridges I plotted, I came to the conclusion that the frequency response is set by the design of the coils and pole pieces while the quality of the sound is from the design of the stylus assembly (I could be wrong). My next experiment is to see if I can upgrade a QLM cartridge to an XLM by using the XLM stylus with the QLM body. Since the inductance/resistance of the coils are the same for both cartridges, I’m assuming that the internal components of the two models are the same and the difference between them is in the stylus assembly.
If the ADC QLM and XLM series have the same internal coils and pole pieces, the differences in the FR curves should only be due to the difference in the stylus assemblies. The FR curve of a QLM cartridge with an XLM stylus should be similar to an original XLM cartridge.
What a surprise. There are differences in the FR curves of the XLM and QLM models (mainly in the low frequencies) but that shape remains the same regardless of what stylus is used. So, again it appears the stylus assembly has little impact on the shape of the FR curve. But, even if the coil resistance/inductance is the same, there is something in the QLM coil design that is different from the XLM. The QLM is the budget version of the XLM series so either lower-cost versions or out-of-tolerance coils were used.
Curve of the original QLM: The low frequency curve is rather bumpy but it does smooth out over the rest of the curve.
QLM using the XLM III stylus: The XLM stylus did not smooth out the low frequency portion of the curve.
Curve of the original XLMIII: No bumps or peaks; very smooth over the entire frequency range
With the QLM36III stylus: Some small bumps but overall, smoother compared to the original QLM curve.