Dynavector XV-1s loading question.

>30 is the right answer. In most systems, the number has been in the 100-150 range. In some rare configurations, I've found 35-50 works best.

Now, with my Atma-sphere MP-1, I am running wide open (no loading resistors). Just when you think you have it nailed down, your world turns upside down.

I'm beginning to think that we're not hearing so much the ultrasonic resonance peak direcly as much as we're hearing how this peak gives some phono stages fits (throws them into resonance).

I'd be curious to hear the thoughts of some preamp designers on this.

Cheers,
Thom @ Galibier

Thanks Palasr,

As usual, a brilliant post from Jonathan. The last paragraph bears re-reading, and explains very concisely the reason this is all so system dependent.

Amen, brother Jonathan!

Cheers,
Thom @ Galibier

Jonathan, Ralph ... thanks, as always, for jumping in. You always force me to get back to the raw numbers that always explain what I'm hearing.

I think the best we can hope to accomplish, in advising our customers, is to outline the general principles (as we have all done) - providing basic guidelines for fine tuning.

Both of your comments serve to me as objective validation of what I'm hearing, and justify the obtuse answer I always on give loading: "it depends".

So, what we've (re)learned here:

1. All of the capacitances in the cartridge to preamp path (interconnect, Miller capacitance, etc.) contribute to, and interact with the inductance of the coils to create a resonant tank circuit (look it up, if you're interested). This tank circuit can challenge some RIAA stages more than others, and we run the risk of shooting the messanger (the cartridge), instead of the overall solution.

2. The capacitive component of this tank circuit can be altered with a resistive load (look up "RC filter" and "time constant"). Loading can either be the "correct" solution, or a Band-aid.

3. "Just enough" is always the best solution to all of your adjustments. Exercise a delicate hand in applying any adjustment, whether it's loading, anti-skate, tracking force ... whatever.

4. Re-visit your adjustments when you apply a system change. This element was (obviously) most responsible for the wild variance I've experienced with the XV1s loading (anywhere from 35 ohms, to wide open at 47K). Re-investigate whether or not you were using loading as a Band-aid.

5. RIAA stages can go into hissy-fits (pun intentded) if they're not up to the task of handling any of the above. A good design will be more immune to much of the above, but again, the designer has to have a light touch with his implementation, because the "just enough" philosophy applies here as well as it does with the end user in his analog adjustments.

6. This is a great forum, and I learn a lot here, by thinking out loud, and in public. We should not however, underestimte the value of a good dealer to help you save time and money in navigating this minefield we call analog reproduction. They can save you countless experimental iterations (dealer disclaimer) Sharing anecdotal information is extemely helpful, but it is highly unlikely that any two audiophiles will have every element in their signal path identical to one another, so this advice needs to be understood in that light.

Cheers,
Thom @ Galibier

Oooo ... wait a minute! I re-visited items 1 & 2 (resonant tank circuit).

The formula for resonant frequency is given by:

res. freq. = 1 / [2 * pi * sqrt (L * C) ].

I believe this is the net capacitance, but what I'm not clear on is whether the resistive load is taken into account - whether we're talking about the net capacitance as defined by the RC circuit (including the resistive load), or whether the only effect is the raw capacitive elements - without taking the "R" (resistive load) into account.

I believe it takes the resistive load into account, but perhaps Ralph can answer this question for us.

Cheers,
Thom @ Galibier

Tuning - reminds me of one of my other loves - guitars.

As it applies to analog, I recall an instance at a music shop where the mother wanted to return the guitar she bought for her son ... because it was out of tune!

Fortunately, our analog front ends are more stable than that (grin).

Cheers,
Thom @ Galibier