Question about input trim

Actually it's best to have the highest gain set at 0dB (i.e. the quietest source).

Other 'louder' sources should be trimmed, with a MINUS dB. 

Essentially you need to trim the input source, rather than artificially boost it in a digital domain.

Adam Zielinski posted:

Actually it's best to have the highest gain set at 0dB (i.e. the quietest source).

Other 'louder' sources should be trimmed, with a MINUS dB. 

Essentially you need to trim the input source, rather than artificially boost it in a digital domain.

Thank you. That makes perfect sense. 

Andy - you profile does not list your gear. From your question I gather you are running one of the Uniti range or N streaming amps. Hence my comment on the boosting in the digital domain.

Ah sorry. I have a uq2 and use it with both a turntable and a NAS. And I have a high output MC - so the analogue is quite quiet. 

But I imagine the same rules apply, keeping the analogue at 0db and attenuating the NAS down with the trim. 

Andy Barratt posted:

Ah sorry. I have a uq2 and use it with both a turntable and a NAS. And I have a high output MC - so the analogue is quite quiet. 

But I imagine the same rules apply, keeping the analogue at 0db and attenuating the NAS down with the trim. 

I'd say so.

I don't understand the 'NAS trim' though. Aren't you connecting your NAS to a switch, and your UQ to the same switch with LAN cables?

Adam

Perhaps I'm getting my terminology wrong. I mean the upnp input trim I think? 

Andy Barratt posted:

Perhaps I'm getting my terminology wrong. I mean the upnp input trim I think? 

That's Ok - all clear now. UPnP input trim it is.

Another option: just leave everything at 0dB and just turn the volume up when you play vinyls. Although with a correctly set turntable and a decent phono stage there shouldn't really be that much of a difference. Definitely not 10 dB.

A lower line signal level from your phono stage may mean (with a MC cartridge): check your loading and capacitance. Also if there is an input trim setting there, try adjusting it. If none helps, than you just have a quiet phonostage One of my turntables is like that. The other one is actually 'louder' than my NDX.

Adam

Thanks. Yes my stage is a graham slee gram amp 2se which whilst unadjustable - is supposed to be slightly louder for homc set ups. I know it's all relatively budget stuff, Im quite new to Naim and better audio gear - baby steps!

It's a very decent phono-stage! 

Enjoy the music 

I noticed HH mentioning this issue in another thread, and a search brought me to this thread.

I'm just wondering why the advice is to set the quietest source to 0 and trim other sources down, as opposed to the other way around. Does anyone know? Does it vary according to whether the source is analogue or digital?

I ask because it seems like it should be the other way round to me. As far as I understand it, the volume dial in a preamp attenuates the signal, rather than boosts it. So intuitively it seems that less attenuation is likely to be better than more - leave the signal alone as much as possible and it'll have a better chance of coming out cleanly at the other end.

Maybe it's something to do with digital signals (I'm thinking of it in the context of UPnP vs iRadio vs analogue input on my 172, and HH's comments about his 272). Maybe it's only a marginal difference in any case. Just wondered if anyone knows for sure, and why.

That's realtively easy. Think about it this way - what does the AV bypass do? It bypasses all the circuitry and goes directly into a power amp, at FULL power.

So the talk is of an attenuation of a signal, rather than a true boosting of it. Quiet sources need less attenuation, etc, etc.

Digital boost is also a bit of a fallacy - it makes the signal 'louder' but starts to add unwanted digital artefacts.

In other words - when we turn the volume knob UP, what in essence is being done at a pre-amp stage, is that we make it less quiet for the power amp working at FULL tilt.

Adam

Thanks for the explanation - the quieter signals needing less attenuation part made me think 'of course, dur!'.

But then I thought about it a bit more... If the ideal is to have as little attenuation on analogue sources as possible, then surely that suggests having them as close as possible to +10 trim. Analogue signals are only attenuated and never boosted at the preamp stage, aren't they? So in effect, the maximum trim value will be closest to the ideal 0dB.

While with digital sources, if (undesirable, possibly artefact-producing) boosting occurs at positive trim values, that suggests that best performance will be at as close as possible to 0 trim. If digital attenuation also affects quality, then with multiple digital sources, it'd be best to have them average at 0 trim (or leave them at 0 and use the main volume control instead). Only if digital attenuation has no effect on SQ would it be desirable to have the quietest at 0 and the rest at negative values.

Or am I being thick (readily willing to admit it if so!)?

On the Uniti family of products, it won't matter tremendously whether you adjust trim upward or downward.

The signal passes through a switched attenuator–if you raise or lower the volume, the input trim is simply an offset against the (soft) value being set by the volume slider on the app (or via IR handset) - so there is exactly no difference whatsoever. The same voltage comes out either way, as the attenuator is always active, so you should adjust to levels that make relative sense to each other.

Compare this to a standard Naim preamplifier with a volume & balance potentiometer pair, where adjusting the input level externally to the preamp (then adjusting via the volume potentiometer) will provide a different gain structure.