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Just a couple of questions trying to understand...Why is the Sweetest Whispers 15K when the Foreplay II used 100K pots? Would a "100K" Sweetest Whispers allow me to keep the volume turned down low or is that what the input padding resistors are for? I will be using my pre-amp at work and need fine control at low volumes.
Does the audio signal go through all the resistors when turned all the way up? Isn't it considered "bad" to have resistors in series from an audio perspective?
Follow Ups:
> > Why is the Sweetest Whispers 15K when the Foreplay II used 100K pots?The Sweetest Whispers was designed to meet three requirements: 1) high enough impedance in a Foreplay to properly load a Seduction, 2) reduce the Foreplay gain by 10dB, and 3) a low enough impedance to work by itself as a passive preamp. It is normally configured as a shunt atenuator, with 33k to 48k input resistance, the minimum load for a Seduction. The shunt mode also provides the 10dB sensitivity reduction. It can be configured as a normal potentiometer at 15k, which is about the highest practical impedance for a passive preamp. (Actually, Doc B ran his system for several months with the passive version, and it worked pretty well with a Seduction.)
> > Would a "100K" Sweetest Whispers allow me to keep the volume turned down low or is that what the input padding resistors are for?
That's what the padding resistors are for. Some systems need much less gain than others, and a shunt mode control is ideally suited to that application - by changing the series padding resistors, you can get an attenuation range of 10dB to 28dB, and an even wider range with custom resistor selection.
> > Does the audio signal go through all the resistors when turned all the way up?
Yes, it does.
> > Isn't it considered "bad" to have resistors in series from an audio perspective?
Some people think so. But then, capacitors are considered to be "bad". Steel leads on any component are considered "bad". Tubes are said to be "bad, except by those who insist transistors are "bad". Copper is "bad", unless you think silver is "bad". There are very few amlifiers that have no capacitors, no steel leads, no tubes, no transistors, no copper, and no silver.
Let's put things in perspective:
1) Ordinary potentiometers (usually conductive plastic) are usually considered the lowest quality, but are still good enough for a majority of high end audio gear. Cost around $10 and up.
2) Many (including myself) think that carbon potentiometers, although the cheapest, sound a little better than conductive plastic. Cost around $4 and up.
3) Almost everyone thinks that a switched attenuator with metal film resistors sounds better than any pot. Cost around $100 and up, except Whispers which has fewer steps to keep the cost down.
4) Many repeat the claim that a full ladder is even better. Cost $200 and up, because it takes twice as many resistors and switch contacts.
5) Most agree that any of the above controls in a shunt mode configuration sounds better than in a potentiometer connection.
Those costs are of course just approximate, so don't beat me up if you've found something at a different price! But you get the idea - Sweetest Whispers is not the best attenuator available, it's just the best sounding option for less than $100. If you have several hundred dollars to spend on an attenuator, there are better ones out there. But if you have several hundred dollars to spend on improving your preamp, there are probably many other things (caps for instance) that will cost less and make a much bigger difference.
In the FPIII, with the volume turned all the way up, (full clockwise) the incoming audio signal passes through only the series (typically 33K) resistor, and the 15K resistance serves as the grid-to-ground resistor. The input resistance varies from 48K at CW poassition (full volume) to 33K at at the fully CCW position, if the series resistor is 33K.At lower levels, the incoming signal passes through the 33K resistor and then any of the ten resistors which are "upstream" from the "wiper" switch contact.
At line level signal voltages, any noise that may be generated by the resistors is minimal.
"At lower levels, the incoming signal passes through the 33K resistor and then any of the ten resistors which are "upstream" from the "wiper" switch contact."So are you saying that if I have the volume at 3 clicks the signal will go through 8 resistors (33K and the 7 after the third click)?
I thought the goal with attenuators was to go through only one (two including the padding) resistor?
At "3 clicks" the incoming signal will pass through the input series resistor (33K typically) and then seven resistors, for a total of eight resistors in series. The lower the volume setting, the larger the number of resistors that the signal will pass through. At the lowest audible setting (1 click) the signal passes through a total of ten resistors to arrive at the VA grid. At Maximum volume (Position 11) the signal passes through only the 33K resistor. Yes, it does still travel through all the other resistors in series to ground, as well, but this isn't considered as being "in the signal path".This approach is different than in the "stock" FPII, in which the signal input connects to the high side of the 100K potentiometer, the wiper / slider connects to the VA grid, and then the low side of the pot to ground. THis method, the input resistance is always 100K, and the resistance from grid to ground can vary from zero to 100K ohms.
In one of the Ladder Attenuators. like the Goldpoint, etc, the signal only ever sees two resistors, at any of the 23 positions. One resistor connects (through the 23 position switches) to the VA grid, the other resistor connects then to ground. In order to do this, the stepped attenuator reauires 46 resistors and 3 or 4 pole, 23 position switch (the lower cost Taiwan / Hong Kong stepped attenuators may use only a 2 pole, 23 position switch). The SW uses a 1 pole, 11 position switch and ten resistors in series (plus the input series 33K resistor).
The 12th (or 24th) position is used as a physical "stop".
In terms of voltage, 3 dB equates to a 1.41:1 ratio, 6 dB is a 2:1 ratio, 10 dB is a 3.16:1 ratio and 20dB is a 10:1 ratio. In terms of power (wattage) these numbers are squared (eg, 20 dB power gain equates to 100:1 incerase).
Just read this from the Sweetest Whispers product description:"For use in active circuits the basic 15K series design is re-implemented as a shunt attenuator, often regarded as the most transparent sounding attenuator configuration, putting only one "padding" resistor in the signal path."
This says that the padding resistor is the only one in the signal path. Which is it?
What everyone is saying is the sweetest whispers is a series attenuator and your desciribing a shunt attenuator . The shunt has one resistor in series and forms a voltage divider with another resistor to ground which you chose via the attenuator switch . You have way less soldering connections and series resistors to travel thru . I'm using this in a 100k config using riken ohm resistors and like the sound Very much .
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