Help me understand line voltage please

[Mister_magister]

I'm talking about RCA/XLR line out/in. But from the beginning

I have home theatre setup with adam t5v as LR, amp for the rest of the speakers and Asus Xonar u7 mk2 dac. At first there was issue where t5v's weren't getting loud enough at full volume on the DAC so i bought some cheap chinese preamp pcb and that solved the issue for t5v's. Someone recommended me to buy focusrite 18i20 because it has 4V line out and that would be perfect for t5v.

Now here's where confusion begins, because stupid me decided that he wants to understand this and math just doesn't make sense. So to gather information:

t5v has SE/BAL input which you can choose between and the switch also changes input sensitivity from -10dBV/+4dBu (yes it's cursed, move along)
Xonar has line out SE 1 Vrms (2.828 Vp-p)
18i20 has line out +16 dBu, balanced line out (and if i get SE it's halfed i imagine [correctmeifi'mwrong])

converting units to the same ones (dBu/Vrms) and talking only about SE, using this https://sengpielaudio.com/calculator-db-volt.htm

• t5v - has -7.8dBu/0.3Vrms input sensitivity
• xonar - has 2.2dBu/1Vrms line out
• 18i20 - 16dBu = 4.8Vrms /2 = 2.4Vrms / 9.8dBu

t5v's have their volume knob set at 0dB (aka neutral) so with 0.3Vrms sensitivity, my understanding (from this very forum) is that 0.3V on input should be enough to get like 106dB? the SPL?
and my xonar has 1V rms out so that should be 3x more than enough to get the t5v loud enough right? well it's not not by a long shot
and 18i20 would be sending 2.4Vrms which is INSANELY higher than 0.3Vrms,

How is it okay to send that much voltage on something that has 0.3Vrms senstivity? Why isn't 1Vrms enough for 0.3Vrms? Why doesn't math add up? Did the audio engineers do meth instead of math? Some kind soul please explain to me what am I missing here

PS: t5v on bal get +4dBu of senstivity which is like 1.2Vrms which is "Studio level international" i saw on the website, but then focusrite spits out +16dBu which is 4.8Vrms which is 4x more what is even going on

 

[staticV3]

t5v's have their volume knob set at 0dB (aka neutral) so with 0.3Vrms sensitivity, my understanding (from this very forum) is that 0.3V on input should be enough to get like 106dB? the SPL?

"Input sensitivity" can mean different things.

While Genelec for example clearly states what voltage results in what SPL:


Adam just specifies a max SPL of 106dB and a switchable +4dBu/-10dBV input sensitivity.

With Power Amps, input sensitivity usually means the voltage required to clip the output with the Amp's volume turned up all the way.

The way I interpret it, that would mean that the T5V needs 0.3Vrms in to clip the output (=106dB SPL), with volume set to max (= -10dBV input sensitivity, level set to +18dB).

It would be nice if Adam adopted Genelec's approach of clearly linking input level to output SPL.

 

[Blumlein 88]

Does not that speaker have +18 db on the volume knob? I see staticV3 just answered the same.

Likely that input sensitivity is if you have the volume knob on +18 db. And yes they are quite unclear about all this. I hate it when brands do this on something so simple. All they needed to say was sensitivity ratings are at max volume setting of +18 db.

And the input sensitivity for .3 volt is only for the RCA input. Again nothing other than a simple lack of clarity on their part.

If you used some adapters from the 18i20 on the RCAs what is that like 10 db of extra volume? That isn't insanely high. Gives some headroom for a device that may connect to many different devices. You could turn the volume knob down to a level from +18 db to insure you never overdrive it if you wished.

Was already a topic once before on this same speaker.

Adam T5V Volume Concern

I have a pair of Adam T5V on my desk connected with balanced cabling to a Topping L50 amp and SMSL DO1000 dac. The monitors run passthrough to the L50 and I control volume via the dac. I run EQ on my Mac via HLConvolver and Blackhole. For 95% of my listening the volume is good, but if I want to...

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