[cuiter23]

Hey guys, I am having a hard time wrapping my head around this.

I am planning to use my Mojo as a DAC to bypass the internal DAC on my Sony HAP-S1 and just use the Sony as an amplifier.

I will be using a 3.5mm to RCA cable from my Mojo to the Line-In on my Sony HAP-S1.

Are there going to be any double amping issues? I'm assuming the Mojo will have already amplified the signal before it is transferred to the Sony.

My main goal is to use the Mojo's DAC (as I believe it is superior to the Sony). But if double amping is going to negate these benefits, I may need to second guess myself.

Any help would be greatly appreciated. Thanks!

 

[Roseval]

The Sony is an amp with an analog input.
This input signal will be amplified

The Mojo is a DAC with a headphone out hence there will be a (headphone amplifier) and volume control as well.
So indeed double amplification but all sources translate the input (LP, Tape, FM, AM, CD, audio file) to an analog signal using some kind of amp.
You might wonder if this is a problem after all.

Anyway, get that cable and give it a shot.

 

[David E]

On the Mojo, put it in line out mode when connecting it to the amp. You'd press both volume buttons together when turning the unit on. Both volume balls will be blue. This mode won't be remembered so when you turn it off, it will reset back to the previous stored volume.

 

[cuiter23]

On the Mojo, put it in line out mode when connecting it to the amp. You'd press both volume buttons together when turning the unit on. Both volume balls will be blue. This mode won't be remembered so when you turn it off, it will reset back to the previous stored volume.

I think the line out mode locks it at 3V. Most amplifiers tend to prefer 2V. Trying to see how many steps down it will take from the two light blue balls to get it down to 2V.

 

[ClieOS]

The Sony is an amp with an analog input.
This input signal will be amplified

The Mojo is a DAC with a headphone out hence there will be a (headphone amplifier) and volume control as well.
So indeed double amplification but all sources translate the input (LP, Tape, FM, AM, CD, audio file) to an analog signal using some kind of amp.
You might wonder if this is a problem after all.

Anyway, get that cable and give it a shot.

The problem with double amping is going from using one analog gain stage (*generally involves opamp of some sort or similar design) after another analog gain stage, so noise from the first gain stage gets amplified by the 2nd gain stage and thus you are not getting the best SNR when compared to amping an line-out signal (* =pure analog signal coming out of DAC chip). Mojo however doesn't actually has any analog gain stage - it has more or less a digital gain stage (*all done inside the DAC chip) follows by transistors buffer stage, then directly to the headphone. Thus it really doesn't have any issue with double amping since technically there is no first analog gain stage that you can double-amp to begin with. In simple term: double amping is not an issue with Mojo, whether you connect it to an headphone or to another amp. However, as @cuiter23 said, you want to set it to 2V (or just slightly less than 2V) so you won't likely to clip the amp it connected to. Also, Mojo's 3V 'line-out mode' is more of a convenient setting than an actual line-out mode. Mojo's amp-less implementation means that you get almost just as good a signal at 2V as it is at 3V so setting it either way is just fine.

 

[cuiter23]

The problem with double amping is going from using one analog gain stage (*generally involves opamp of some sort or similar design) after another analog gain stage, so noise from the first gain stage gets amplified by the 2nd gain stage and thus you are not getting the best SNR when compared to amping an line-out signal (* =pure analog signal coming out of DAC chip). Mojo however doesn't actually has any analog gain stage - it has more or less a digital gain stage (*all done inside the DAC chip) follows by transistors buffer stage, then directly to the headphone. Thus it really doesn't have any issue with double amping since technically there is no first analog gain stage that you can double-amp to begin with. In simple term: double amping is not an issue with Mojo, whether you connect it to an headphone or to another amp. However, as @cuiter23 said, you want to set it to 2V (or just slightly less than 2V) so you won't likely to clip the amp it connected to. Also, Mojo's 3V 'line-out mode' is more of a convenient setting than an actual line-out mode. Mojo's amp-less implementation means that you get almost just as good a signal at 2V as it is at 3V so setting it either way is just fine.

Oh wow, that's great news.

As for the dedicated line-out function, do you know how many steps it is from 3V to 2V. I'm heard it is anywhere from 4 to 5 clicks down. Do you have a definitive answer to that?

Thanks so much for the clarification!

Kevin

 

[ClieOS]

Oh wow, that's great news.

As for the dedicated line-out function, do you know how many steps it is from 3V to 2V. I'm heard it is anywhere from 4 to 5 clicks down. Do you have a definitive answer to that?

Thanks so much for the clarification!

Kevin

Here you go:

Turn the volume all the way down until no LED light on the volume control, then press '+' exactly 68 times - that will give you the 'lite' indigo color on both '+' and '-', which is roughly 1.9Vrms. You will notice 67 times is deeper blue on '-' and indigo on '+', then 68 times turns both to indigo, that's how you can tell it is right on 1.9Vrms. 69 times will go to around 2.1Vrms, which is over your limit.

If you fancy the other way around, it is 26 times '-' from the max volume.

Nothing to confuse about, that's exactly what it is - 1.9Vrms is 4 clicks below 3Vrms, or 68 clicks above mute. What you have confused is probably thinking voltage over volume range should be linear, which it is not.