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  Dynavector XV-1s loading question.
I have a transformerless (no step up) phono stage (Wavestream kinetics) with 62db gain.

What would the optimum loading be based on the XV-1s specs?
Impedance= R=6 ohms, L=18 micro Henry
Recommended load=resistance > 30 ohms

I can only adjust the resistive loading.
Frank_sm  (Threads | Answers | This Thread)

08-10-10
  Responses (1-24 of 24)
Click title to read one, or click date to read all below it.

08-10-10   So what's the problem?   Doak

08-10-10   Try around 100 ohms and go from there.   Dan_ed

08-10-10   means "greater than" so try any loading from 30 o ...   Pbnaudio

08-10-10   Try 500 to 1000 ohms. you just might find a fuller, suppler, ...   Opus88

08-10-10   No no no....100 or 200 ohms....but then it's your ears...   Chashas1

08-11-10   As you approach 30 ohms from higher values, you may notice a ...   Lewm

08-11-10   There is no specific recommended loading for any cartridge - ...   Larryi

08-11-10   30 is the right answer. in most systems, the number has bee ...   Thom_mackris

08-11-10   Thank you all for taking the time to post. i had initially u ...   Frank_sm

08-12-10   Thom, allen wright (a noted preamp designer) is very outspok ...   Lewm

08-12-10   And they may well sound better at 47 kohms, on allen's phono ...   Dan_ed

08-12-10   Which answer above makes the best sense? 35-50, 100-150, 100 ...   Opus88

08-12-10   I've played around with loading quite a bit (though not on a ...   Palasr

08-12-10   Thanks palasr, as usual, a brilliant post from jonathan. t ...   Thom_mackris

08-12-10   Dan_ed nailed it. i use the xv-1s and xv-1t on 6 phono stag ...   Audiofeil

08-12-10   Dear frank: i think that with 40 hours in yor cartridge righ ...   Rauliruegas

08-13-10   Hi raul, i agree. i'm not stressing the fine details yet but ...   Frank_sm

08-14-10: Jcarr
Thom, Palasr:

Yes, 28dB is a lot! (25 times greater energy than the flat-response amplitude)

My experience has been that when a low-impedance MC cartridges changes in sound and energy balance due to different electrical loading, what we are hearing are mainly the effects of altered distortion characteristics (particularly intermodulation distortion) in the phono stage, and to some extent, dynamic compression of the cartridge (which is what too-heavy loading will do). The oft-repeated mantra that loading-induced alterations in the sound and energy balance are due to the frequency response in the audible frequency range changing is a myth, because there is no measurable sign of this happening. OTOH, factors that I don't see normally mentioned will cause significant changes in the measured frequency response, such as when the ambient temperature changes by a few degrees, or where on the LP the cartridge happens to be tracking (groove radius).

I should now debunk another myth regarding loading, which is that low-impedance MC cartridges are insensitive to capacitive loading. OK, the MC cartridges themselves aren't particularly sensitive to capacitance, but the inductance of the cartridge coils will resonate with the distributed capacitance of the coils and the capacitance of the tonearm cable to create a high-frequency spike, and this spike certainly is sensitive to capacitance. In general, the less the capacitance the better. Having more capacitance (across the plus and minus cartridge outputs) will increase the magnitude of the high-frequency spike and lower its frequency, neither of which is good news for phono stage stability or phase response.

Generally speaking, the greater the capacitance across the plus and minus cartridge outputs, the heavier the resistive loading needs to be to control the resulting high-frequency spike. Conversely, less capacitance allows the resistive load on the cartridge to be reduced, which will benefit dynamic range, resolution and transient impact.

From the above we can deduce that tonearm cables for low-impedance MCs should have low capacitance. As a test, some time ago I built some 5-pin low-capacitance tonearm cables of 1.2m length (configured for use with a Graham Phantom). Including 5-pin and RCA connectors, the smallest-capacitance versions got down to 32pF, there was an intermediate version at 42pF, and the highest-capacitance version had 50pF. I felt that these low-capacitance tonearm cables resulted in greater flexibility in loading, a more natural tonal balance with better dynamics and resolution, and were a worthwhile upgrade.

hth, jonathan carr (preamp and cartridge designer)

PS. The possible frequency range occupied by the high-frequency resonant spike also includes the frequency range encompassed by LP pops and ticks, and these can likewise be of quite large magnitude (larger than any music signal inside the groove). Just as with the high-frequency resonant spike, controlling pop and tick energy is the task of the phono stage (although it is a big help if the cartridge has a low-mass moving assembly). The phono stage and cartridge can have an immense influence on how "noisy" your LPs appear to be.

Jcarr  (Threads | Answers | This Thread)


08-14-10   The load will generally reduce capacitive effects in the cab ...   Atmasphere

08-15-10   Jonathan, ralph ... thanks, as always, for jumping in. you ...   Thom_mackris

08-15-10   Oooo ... wait a minute! i re-visited items 1 & 2 (resonant ...   Thom_mackris

08-15-10   thom, i believe that the resonant frequency is determined pu ...   Almarg

08-16-10   Thank you jonathan for furthering our collective thinking on ...   Palasr

08-16-10   Tuning - reminds me of one of my other loves - guitars. as ...   Thom_mackris


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