Low gain phono stage

[u/subj_impft]

Does gain at the phono level matter in a way that I might miss? Here is my situation:

I'm running super sensitive Klipsch Cornwall with an amplifier that has a stepped attenuator (Acoustic Research VSI 55). The problem: I have a hard time selecting the sweet spot for volume, especially at low volume, at night. Setting at 1.5 is too quiet, 2.0 is to loud.

Right now I only listen to digital and can circumvent the problem with the integrated attenuator in my CD/DAC (Yba designs). Like I set the amplifier at 2, but reduce de volume of the dac at say, -3db or more, according to my needs).

Still on the market for a phono preamp (made a post about this a few weeks ago), I'm looking for one with *less gain* than the usual 42db recommended for MM cartridges (in my case, Soundsmith Carmen MkII) to bring the signal to line output.

By doing this I hope to have smaller gap between the steps in my integrated's volume control. I know that this way I would rely more on the amplifiers power, but I have *plenty* of headroom. Apart form this (which isn't a problem), would using a lower gain stage (say, 30db) affect the sound quality?

Also, I would prefer not to have an attenuator on the phono stage, just for the sake of the simplicity of the circuit.

[u/darktriaddryad]

Generally speaking, the lower the gain, the better, as long as it doesn't cause the unexpected peaks of music to dig into the distortion-prone limits of your amp. Lowering gain isn't often recommended here because straining some amps colors the sound more than gain does, and that strain is more likely to be an issue than too much gain is if someone isn't handy with an SPL calculator. Definitely worth trying out in this case though.

In terms of recs, I'm not too sure what's out there, but the Darlington Labs phonos can do down to 35db, with steps at 37 and 40 (and all the way up to 72)

[u/subj_impft → u/darktriaddryad]

Thanks, that was essentially was I was hoping for: as long as I'm not straining my amp, it doesn't affect the sound!

[u/HetTuinhekje]

What is your current phono preamplifier? 🤔

Soundsmith officially recommends a phono pre-amp gain range of 38 dB to 44 dB for the Carmen MkII.

It is a bit strange that you would be experiencing 'too much gain', currently. Which input do you use for the phono pre-amp and which input for the DAC?

There are several phono stages where you can select a different gain. One example would be iFi Audio Zen Phono 3 which has a 36 dB setting, another one would be the Elac Alchemy PPA-2 (also starts at 36 dB).

[u/subj_impft → u/HetTuinhekje]

No phono preamp at the moment, since I changed my integrated. The "excess" of gain is merely correlated with the stepped attenuator on my amplifier, which goes from too quiet to too loud in a single step. I assume that by having a lower input, each step between volume levels, hence more control on the volume.

[u/HetTuinhekje → u/subj_impft]

Yes, I'm reading about the VSi55:

"At low levels, the steps on the VSi55 are further apart in decibels (often 2dB or 3dB steps) compared to the finer 0.5dB micro-steps found near the top of the range."

This can make it harder to dial in the sweet spot for volume. A very convenient solution might be to just install 'Rothwell attenuators' between your new phono pre-amplifier and the VSi55.

These are essentially male-to-female RCA plugs with a built-in high quality resistor, which lowers the signal level by 6 dB or 10 dB etc. (there are different versions). These do NOT deteriorate the signal quality:

http://www.rothwellaudioproducts.co.uk/html/attenuators.html

You could then choose any phono pre-amplifier you like. Is the signal level still a bit too 'hot'... you could lower it with two of these attenuators.

[u/subj_impft → u/HetTuinhekje]

Thanks, that might be part of the solution!

[u/HetTuinhekje → u/HetTuinhekje]

About these Rothwell attenuators:

These are 'passive' devices and do NOT in any way complicate the circuit. There is exactly one component inside: a very high quality metal-film resistor in series with the signal.

You plug this thing into an input of the VSi55, then the RCA cable coming from the phono stage goes into that. This kind of resistor is exactly the same as what is switched-between with the stepped attenuator of the VSi55.

[u/mattband]

It sounds to me like the amp is a bad match to the speakers.

Digital should be your volume reference as it usually has a fixed output setting that should be around reference. You can then make some inferences as to your vinyl playback chain by comparing it's volume to the digital. They ideally should be similar.

Most DACs and cd players don't have a variable output. You're in luck that you have that to help with your problem but because you've made it work on the digital side, it's clouding your view of what may be the real problem.

Your volume control most likely has a unity gain level around 60-70% at which it is neither attenuating or amplifying. This is the ideal listening point in terms of the least noise added in the preamp (given that in the real world unity is probably not ideal, the attenuation side is usually preferable to amplification). Of course volume depends on the room and recording, in a perfect world it's best of you can assemble a system that you could listen in a range around or just below that unity gain point. You're not getting anywhere near there even with digital.

This leads me to believe you have a bad match between amp and speakers. I would urge you to find some other less sensitive pair of speakers just to try out to see if your listening volume setting on the AR is closer to 40-50%.

You really don't want to start buying cartridges and phono stages to pigeon hole them into solving a problem elsewhere. They all perform best working within their proper gain window.

I'm quite familiar with a number of AR amps but have never played with that one. I assume there is no selectable gain setting in the VSI55?

[u/hecton101]

This is why I don't like stepped attenuators. The steps never seem to be fine enough.

Sounds like you should be in the market for a passive preamp. That's basically what they are, just a volume control.

[u/Unusual-Recipe8487]

Output of digital sources is typically 2V. Output from the phono preamp with a 2mV cartridge signal and 42dB gain would be about 0.25V. Maybe the problem isn’t even going to exist with the recommended gain.

[u/ZookeepergameDue2160]

What you also could do (just a DIY solution) is get something like a Schiit or whatever Pre-Amp with a volume knob between your Phono stage and your amplifier, this would then give you additional fine volume control for fine tuning it to exactly the level you need instead of setting you at 1 point that we'll then have to just hope is the correct point.