Evolution 20 questions

[Simonml]

Hello,

I am new to this site, thank you for the add!
I just found this site in looking for reference material for my Evolution 20 preamp. Not the SE model. I hope somone out here may have some insigh.

This preamp sounds amazing. Ine quirk is that the volume control does not seem to cut off all the sound when it is all the way down. It does make a static sound when i increase/decrease the volume. Have anyone ever encountered this.

Aside from that it is that the preamp overall and especially the phono is great!

Cheers,

Simon

[admin]

Welcome to CJO, great to have you with us.

I would use some deoxit contact cleaner on the volume control. Just spray some in there and turn it up and down numerous times (with the unit off and unplugged obviously).

[Simonml]

Thank you. That will be a project for the weekend!

[MLAS]

Or you have DC on your pot...

[roberto]

Hola,
If your speakers are very sensitive, it is normal when you go up or down with the knob. CJ uses a very careful way to bring the level up or down. It is a precision +- 0.7dB. So you can adjust precisely the level that you want to listen. Yes, I know, it is annoying...and there is no way to take this odd noise off.

Happy listening!

[MLAS]

Hola,
If your speakers are very sensitive, it is normal when you go up or down with the knob. CJ uses a very careful way to bring the level up or down. It is a precision +- 0.7dB. So you can adjust precisely the level that you want to listen. Yes, I know, it is annoying...and there is no way to take this odd noise off.

Happy listening!

My speakers (Infinity) have a very low sensitivity of 82dB and I clearly kept hearing the noise when switching to another set of resistors.

[admin]

My speakers (Infinity) have a very low sensitivity of 82dB and I clearly kept hearing the noise when switching to another set of resistors.

Was it static or a quick click between volume settings? A quick click is pretty normal. "Static" would be unusual.

[MLAS]

These were static clicks. Couldn´t get rid of them and tried German Deoxit contactcleaner variant 'Oszillin'.
It didn´t really bother me it was a very good pre-amp which should have gotten a Premier status.

[roberto]

MLAS,
If you find the way to suppress that odd noises coming from the volume relays, please tell us. Even Mr. Jeff says that those noises are a normal behavior of the preamp volume control. All these days CJ preamps uses these volume type control.

Here is a replay to me from Mr Jeff Fischel...

The attenuator employs 12 double pole double throw relays , at the exact multiples of 10,20,30, etc., all 12 relays are activated at the same time. It is common to hear a “tick” noise thru the speakers at these display intervals. This is a result of the relay tapping on the grid of the tube. Sometimes this noise can be reduced by replacing the 6922 tube , but the noise will never completely go away. The static sound heard at display settings of 10,20,20, etc. is odd. I would recommend visually inspecting all of the attenuator relays and resistors solder connections.

Happy listening!

[MLAS]

Hi Roberto,

That will explain why there's no solution for it.
It emenates from the design. Premier 7 and 10 will have the same behaviour then.

Thanks for this informative post.

[AnotherJohnson]

Hi Roberto,

That will explain why there's no solution for it.
It emenates from the design. Premier 7 and 10 will have the same behaviour then.

Thanks for this informative post.

It is a part of the CJ charm. Admin has pointed out that the clicks give him audible feedback when the display isn’t visible from his position, so he’s characterized the click click click as useful/beneficial in his circumstance.

It does not affect the actual musical sound, so there’s no harm in it. But it is unique among high end preamps. Even others who use a ladder instead of a pot don’t click click click as volume is changed.

[Joe Appierto]

Both my old 17LS and 16LS2 made that click/clack sound although I heard it from the preamps only not also from my speakers. Initially with the 17LS I found it distracting but in short order I got to depend on it as an auditory cue which pretty much eliminated having to look at the preamp. Plus, c'mon, how often do you change volume to begin with? In my case, at least, not all that often

[admin]

There is an audible click as well on my PV-14L (although only from the preamp and not the speakers).

I think this is a "CJ quirk." Certainly not harmful to any of the equipment.