Anyone try the replica B-60 Fidelity Research VTA?

Dear Lew:

I specifically replied to your statement:

>The load resistor might affect frequency response but not gain.

This is exactly backwards. The load resistance attenuates the cartridge output - the lower the load resistance value, the greater the attenuation. The load resistance _equally_ affects all frequencies that are not part of the electrically reactive area, and as my graphs from the What's Best link show, that electrically reactive area will be in the hundreds of kHz to some MHz.

Ergo, the load resistance value will not affect the amplitude of any frequency that you can hear directly. The exception would if the source inductance is so big that the electrically reactive frequency region is dragged down (by the cable capacitance) into the tens of kHz, but this calls for a MM or MI, while the post directly above your post (the post that you responded to) spelled out LOMCs. One other exception would be if your phono stage designer likes to add huge amounts of capacitance (nF rather than pF) at the phono stage input.

>were you inferring that my statement (essentially, low load resistances that get into the range of less than a multiple of the internal resistance can affect FR of some cartridges) was correct or incorrect

I was pointing out that your statement is incorrect. Due to its operation as an attenuator, using a very low load resistance affects the output level more significantly than the frequency response, unless electrical resonances form a fundamental part of the cartridge's audible frequency response (which again describes MMs or MIs rather than LOMCs).

>I said nothing about capacitance.

Neither did I (at least not on this thread so far).

Although the What's Best link shows that the interaction between cable capacitance and coil inductance is the mechanism causing varying degrees of frequency peaking (reactive resonances), and that resistive damping of this peaking is why you would on occasion want to use a lower-value rather than higher-value load resistance, it also graphically showed what kinds of frequency ranges will be affected by the load resistance value. Hundreds of kHz to some MHz.

Please keep in mind that the quote of yours that I responded to did say:

>The load resistor might affect frequency response but not gain.

Incidentally, it should be stated that although the ultrasonic frequency peaking is caused by the cartridge (and tonearm cable capacitance), it is never part of the cartridge's own frequency response. No phono cartridge that I am aware of has any output in the MHz region. The highest frequencies emanating from the cartridge itself will be when it encounters a cut in the groove, or a raised particle. Such physical damage is not subject to the limitations of groove cutting lathes, and can give rise to large impulses with frequency content extending as high as 150kHz (according to John Curl, some extreme cases may reach 300kHz). Still, some way off from the MHz region affected by the load resistance value.

What the frequency peaking will do is boost any environmental or local noise that is present in the affected frequency region by the amplitude of the peak. Many radio broadcasts occur in the same region (from 500kHz to some MHz) as that affected by the interaction between cartridge inductance and cable capacitance.

If your phono stage is simultaneously asked to amplify the output of your LOMC along with a local AM broadcast which has been boosted by 30dB due to the frequency peaking action between cartridge inductance and cable capacitance and an improperly chosen load resistance value, it is no surprise that you may hear a skewed energy balance, or audible distortion. But that is a phono stage issue. It is not caused by an alteration of the phono cartridge frequency response.

hope that this clarifies sufficiently.

kind regards, jonathan

PS. BTW, the frequency response of a phono cartridge will vary according to the room temperature, and the LP groove radius (upper frequencies fall as the cartridge gets closer to the label). There are various reasons why I consider the frequency response of a transducer (microphone, cartridge, speaker) to be of merely token interest.

Dear Carr, The Romans stated long ago : de gustibus non
disputandum est. That is why we do this all the time
since. I understand your 'problem'. As a kind person very
reluctant to insult whomever but as a scientist obliged
to tell the truth. This is probably only possible with
a careful and diplomatic choice of the used words. But
your separation between objective and subjective aspects
involved give me 'some' idea about the difference between
the younger and older, uh , 'brothers'. I intend to compare
them and eventual keep my conclusion for myself.
I fear this 'huge German' but also want to keep our friendship
intact. The device being ''don't thouch someone else Holy grail''.
Even the Serbian warriors can't do without corps diplomatique
at present (grin).

Dear Jonathan,
I take your point on frequency response, and I am sorry I ever wrote it; it was really beside the point of my post.

On the matter of load resistance, I SAID at least twice, albeit perhaps badly, that load resistance CAN affect gain, but not perceptibly unless the load resistance gets down low enough in ohmic value such that it is less than a multiple of the cartridge's internal resistance. The case in point was 47K. Surely a 47K load is not going to have a perceptible effect on reducing the gain of any MC cartridge. The reason I left it vague as regards the critical minimal relationship between phono input resistance and cartridge internal resistance that seems to preserve gain, is because there does not seem to be much agreement among those "in the know" as to what relationship is acceptable vs what relationship WILL result in a perceptible loss of gain. Classically, if you read elementary texts aimed at audiophiles, the relationship between output and input resistance is often said to be at least 1:10, in order to avoid perceptible loss of gain. But with MC cartridges, I have read all sorts of claims; it seems to be a "muddy" area. Many claim to be able to go below a 1:10 ratio with no perceptible loss of gain. (For example, the legions of Denon DL103 users who select 100R and less to load that cartridge.) I personally have never tried going below 1:10, so I cannot comment up or down, let alone have I taken measurements. One manufacturer who is also a friend of mine suggests that one might progressively reduce load R until one does perceive loss of gain, then go back up to the next lowest value of load R as the optimal choice for that particular cartridge. I've never tried that either. I am guessing you would not approve.

So, back to the original bone of contention, all I meant to claim was that 47K ohms is not going to perceptibly reduce the gain of any MC cartridge. Thank you for correcting the part of my statement that was apparently erroneous, with regard to the effect of load on frequency response. If you say so, I accept that I was wrong. You certainly know more about this subject than I will ever know or need to know.

I fear this 'huge German' but also want to keep our friendship
intact.

Come on....no audiophile discussion is worth such a result....it is no religion
Life goes on ...

Come on ... Syntax. Or is your sense for humour limited to
your own?