Too Much Gain

[Dsper]

Hi,

I am using my CJ 17LS2 preamp with 26 dbl gain into a LP66S tube amp with 0.5 V rms to rated power sensitivity. Coupled with a high gain DAC (Mojo Audio EVO B4B), I want to reduce the gain to better control volume.

1. Where is the best place to insert in line attenuators - a. between the source and the preamp or b. the preamp and the amp? Why?

2. Are there really quality differences between in line attenuators would impact sound quality at the speakers?

Thanks,

Dsper

[admin]

Is the high gain only an issue with the Mojo DAC or with all sources?

[AnotherJohnson]

1. Where is the best place to insert in line attenuators - a. between the source and the preamp or b. the preamp and the amp? Why?

2. Are there really quality differences between in line attenuators would impact sound quality at the speakers?

I have a pair of Rothwell attenuators. As attenuators go, they are well thought of. But I do not care for them at this point and do not recommend them. In the system where I was using them ET7s2 + LP275Ms + hot source like you, they darkened things and made the music sound less real.

With that said, putting them between source and preamp just affects the one source, and if I had to use them, that’s where I’d put them. Of course in that position their input is low already, and the attenuators becomes a bigger factor in the quality of the sound from that source.

If you put them between preamp and amp, you affect all sources. But their input is higher and so the attenuation is less of a factor than it might have been in the other position for that source.

I eventually decided that the Rothwells sounded lousy in either place.

[AnotherJohnson]

After the round with the attenuators I started looking at other options.

Less efficient speakers are low hanging fruit.

Another is a less sensitive amp. .5 V to full volume is excruciatingly sensitive (the LP275M shared this spec). I don’t know what they were thinking.

And a third is a source with lower output. Some, like the dCS series DACs, have as many as four output level choices because of this very issue. The Bluesound Node which admin and I are using had a setting for variable output level, although on my ND8006 the variable setting impairs sound quality.

You can also have mods done to reduce preamp gain. Talk to CJ if you want to do this. Audio Research will reduce gain in the LS28/28SE for $200, or in my case, they shipped me the parts with instructions for free.

[Big Dog RJ]

Attn: dsper
Nice pre-power combination btw, Prem 17LS2 with LP66s!

My local CJ and ARC tube supplier has the LP66s, amongst the many other fine ARC gear he also proudly owns... one in particular a set of monoblocks with the matching preamp and DAC. Several have offered to buy but be refuses, says that this particular gear is SOTA vintage and can never be replaced, so it's just tucked away... but sounds fabulous!

Oh! Getting back to your attenuator thingy... Nah! Wouldn't ever use these gadgets... they'll degrade the sound big time! In which case, there's no point in owning such gear as CJ. Attenuators at this level...? You gotta be kidding!

As AJ suggested, there are other areas / gear in your system that need looking at. Speakers is a start or lowering the gain on something else would certainly be a better option.
This is CJ's Premier series preamps and the much newer LP series amplifiers. They need to be considered with high-quality system matching, not attenuators!

I'm just wondering if some cables or other accessories might help... not sure which exactly in your case. Just take a look at some other gear and see if you can adjust any other elements. I would very very highly recommend retaining the CJ gear as is, without any mods, unless it was unavoidable.

Hope you find a viable solution.
Cheers, RJ

[Dsper]

Thank you for the comments and thoughts.

Interestingly, the majority of CJ amps are all less than 1.0 input sensitivity and the majority of CJ preamps have gain like 25 dbl. It appears that Klipsch and other horn speakers were not CJ's target audience:-)!

I have made a move away from less sensitive speakers and am running Forte IV's right now. They sound pretty good with a Don Sachs DS2 pre and First Watt F7, but my CJ LP66S brings a bit more presence and live sound to the table.

I did insert a pair of Harrison Labs 6dbl RCA attenuators between the 17LS2 and the LP66S. I don't think I am hearing more distortion but it is possible that the edge of the treble is oh so slightly blunted. However; I did not hear this until after I read Another Johnson's comment that "...they darkened things and made the music sound less real..."!

My first reaction was that I am hearing a bit more detail. Is it possible that the attenuators allow the preamp volume control to operate in a better range with lower noise floor?

Googling on this topic seems to come down to one side saying anything added to the signal path introduces distortion, while the other side says inline attenuators are passive resistors and should not add distortion but could allow the preamp volume control to operate in its sweet spot.

Again, everyone's thoughts are appreciated.

Dsper

[AnotherJohnson]

Googling on this topic seems to come down to one side saying anything added to the signal path introduces distortion, while the other side says inline attenuators are passive resistors and should not add distortion but could allow the preamp volume control to operate in its sweet spot.

My take on the passive resistor comments is that

Resistors wouldn’t logically impact the sound, but we know that they do.

Even in guitar amps.

CJ carefully selects their resistors for sound. Upgrades from CJ often include replacement of their “good quality” with their best quality.

Capacitors don’t logically affect sound either, and yet we know that they do.

So … the idea that less discerning listeners say it makes no difference may well be true for them.

If you don’t notice a difference, then it doesn’t matter for you. This may be a good thing because it keeps you from throwing money away on other solutions.

[admin]

Less is more. I would try and stay away from attenuators if possible. But "if possible" is the key term here. If there is a significant volume issue, they may be a last resort.

At the end of the day, listen to your ears. Put them in. Can you hear a difference? If not, don't worry about what I or other people say.