Preamp - 18 dB Gain too low?

Marakanetz- I will defer to your expertise/training.

I will try to find the reference. (It may have been Roger Sanders or Saul Marantz)???

Anyway, It would make sense that as you approach the limit of the volume dial, (lets say it goes from 7:00-5:00 o'clock, Between 12 & 3 quite loud by now!), you are approaching zero gain and not many can let their systems play at full steam without strain or damage to ears or equipment as you mention. The preamp needs to get out of first and second gear to hit it stride. I think I was left to presume that the volume control would sound best when operating in the latter part of the dial.

I have very little knowledge of EE or Audio design other than being a user of such items. I may have completely misunderstood the conversation. Although, I know I have read comments from others stating nearly the same in that their system sounded best with the volume on the pre turned more clockwise. Where that is on any individual dial is another matter.

Do you kind of get what I am saying?...
Mine has 1db detents but will spin forever.

Nguyen787. A very good quote from god! Cheers George

"Nelson Pass,
We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more.
Think of it this way: If you are running your volume control down around 9 o’clock, you are actually throwing away signal level so that a subsequent gain stage can make it back up.
Routinely DIYers opt to make themselves a “passive preamp” - just an input selector and a volume control.
What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection.
And yet there are guys out there who don’t care for the result. “It sucks the life out of the music”, is a commonly heard refrain (really - I’m being serious here!). Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp."

Coming into this late but the first thing you need to do is differentiate between gain and attenuation. Gain is fixed at 18dB and attenuation is variable.

The 800 pound gorilla in the corner is lumping gain and attenuation into an arbitrary setting of a dial without reference.

A decade ago I measured some flavor of the day 10K pot to relate the gain to rotation in both dB and voltage ratio. By no means is this a standard, it is just a statistical sample of one but hopefully it illustrates the issue. (remember these values are for attenuation only)

(Apologies the formatting doesn't hold it is a three column table)

Rotation Db attenuation voltage ratio
7.00.00 AM 0ff NA
8.00.00 AM -50.798242 400
9.00.00 AM -37.669889 78.78787879
10.00.00 AM -28.995433 28.10810811
11.00.00 AM -21.98006 12.14953271
12.00.00 PM -13.492213 4.727272727
1.00.00 PM -8.299467 2.524271845
2.00.00 PM -5.2231697 1.818181818
3.00.00 PM -2.7932399 1.382978723
4.00.00 PM -0.7861947 1.06122449
5.00.00 PM -0 1

This is where it gets fuzzy without the actual numbers of "your" attenuator wrt "clock rotation" If we make the grand leap and assume all attenuators have this particular taper, it becomes easy.

With 18dB of gain, you would have overall unity gain between 11 and 12. (again assuming you have the attenuator I measured installed) This means if you listen at 1-2 the concept of a passive is really not an option since you would actually need gain. (again look back at the assumptions in this story)

Unfortunately there is no bureau of standards for the audio industry so you have either have to roll with it or put in the time to learn some of the basics to make an informed decision.

My gut feel is adding more gain to simply add more attenuation is not the way to go.

It is also important to realize I have only addresses the gain aspect of this situation. There are two other key points that play a more important role in system synergy which are impedance matching and headroom. Unfortunately neither of them can be directly read by the dial rotation value.

dave

Hi Dave,
Thank for sharing the detail of your measurement. I swapped the active preamp CJ 18 dB gain with a passive Lightspeed Attenuator, and I found that most of CDs, I have to push the volume knob to 3 - 5 PM (MAX == 5 PM) to obtain the desirable volume. The low sensitivity amp, 4 V, seems to be an issue. Bought this amp without understanding the input sensitivity spec...

What is attenuation voltage ratio and what does it tell us?

Some amps have high input gain because they are designed to be used with passive preamps which have no gain at all. I can tell you that CJ amps need a preamp with relatively high gain to properly drive them. 18db of gain is higher than average.

I have owned some CJ preamps and they do invert phase. I corrected the phase by reversing the wiring to the speaker binding posts. I couldn't tell any difference myself. It could be because some recordings are already recorded with inverted phase.