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Hi all-

 

I have a pair of AVI DM10 active speakers and sub and I was hoping to bypass the pre-amp stage to try and improve sound.

 

My question is, if I set my Mojo to line level output and press AV on the AVI volume control (apparently this bypasses the pre?), Will I be able to control the volume with the Mojo? Or do I need to set the volume on the Mojo then turn it off and turn it back on with live level mode to keep that volume?

 

I'm hoping to try a quality pre-amp as a demo but I'm interested to try the Mojo as a pre too.

 

Thanks,

Dan.

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Looking at the Mojo manual, it appears that you cannot use volume control when line level input is enabled. And I believe that volume control on the DM10 is available for both digital and analogue inputs.

 

Since you have both, why not try it?

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Thanks @Snoopy8. I have used the line level on the Mojo through the analogue in on the DM10 and you're correct, it does allow volume control from the remote. 

 

However, when I press the AV button on the remote with the Mojo in line level mode it is terrifyingly loud. In fact I only discovered this because my dog has large paws and selected for me.. That got me thinking about why it went so loud. I've since read that it's because  it has bypassed the volume control of the pre and so I'm just getting max volume.

 

This is really just an experiment to see if bypassing the pre on the DM10 will improve the sound. 

 

I use Roon and I'm fairly sure I can control volume output to the Mojo from there even in line level mode.

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The line level setting provides a higher voltage for devices which need it. If your setup works without line level enabled, why not use it? 

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5 hours ago, Snoopy8 said:

Looking at the Mojo manual, it appears that you cannot use volume control when line level input is enabled.

 

This isn't correct. There's nothing special about the 'line level' mode.

 

All it does it allows you to quickly set to to 3Vrms output, instead of clicking up and down manually and having to know which colour corresponds to 3V.

 

But you can manually get there by adjusting the volume...

 

So there's no issues with using Mojo volume control (using it as a pre). You can't really escape using it's built in digital volume control. But there's no reason to either.

 

 

 

Edited by rand129678
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2 minutes ago, Crabsticks said:

OK that makes sense. Thanks for the information, I'll be sitting down for a listen in 2 min!

 

There's a spreadsheet somewhere on Head-Fi Forum but after you set to 'line level' mode (3V), here are the output voltages with each volume button click down from 3V mode:

 

0 clicks down = 3 Vrms
1 click down = 2.67 Vrms  
2 clicks down = 2.38 Vrms 
3 clicks down = 2.1 Vrms 
4 clicks down = 1.9 Vrms 

 

 

Best to start at Mojo's lowest volume and slowly and gradually go up !

Edited by rand129678
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Thanks again all. I have been flat out listening and can confirm it's quite the revelation. I'm frankly stunned that it's taken me three years to try the Mojo as a pre..

 

Clarity, separation, depth, soundstage, resolution, highs/lows they're all better. Absolutely chuffed with the result. Amazing a pre could colour the sound so much. Now I'm keen to try a really good pre!

 

Another question. Say I did buy/borrow a pre, how does the Mojo know to act as just a DAC and not a pre? So if I'm going RCA into a dedicated pre from the Mojo, how does it know to only perform the DAC function? If that makes sense.

 

Thank you for your input to people that responded (and are yet to respond). Grateful for the shared wisdom.

 

Dan.

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8 hours ago, rand129678 said:

 

There's a spreadsheet somewhere on Head-Fi Forum but after you set to 'line level' mode (3V), here are the output voltages with each volume button click down from 3V mode:

 

0 clicks down = 3 Vrms
1 click down = 2.67 Vrms  
2 clicks down = 2.38 Vrms 
3 clicks down = 2.1 Vrms 
4 clicks down = 1.9 Vrms 

 

 

Best to start at Mojo's lowest volume and slowly and gradually go up !

Whilst you may select higher available hypothetical output ,  actual level achieved on  CD or streaming formats rarely ever exceeds +/- 350mv RMS , seen here in light blue with a ( loud ) track from Swiss band Sonar. Peak level is higher seen in dark blue 

 

Given amplifiers are tasked to amplify their input and nothing else ,  ideally  source level RMS, should then match to power amp RMS sensitivity, so all that is needed in between, is simple attenuation, exampled by the specification attached.   

Screenshot from 2020-07-04 20-05-59.png

Screenshot from 2020-07-04 20-13-46.png

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10 hours ago, Crabsticks said:

Another question. Say I did buy/borrow a pre, how does the Mojo know to act as just a DAC and not a pre? So if I'm going RCA into a dedicated pre from the Mojo, how does it know to only perform the DAC function? If that makes sense.

 

Works perfectly fine. Just set the Mojo output to a more 'normal' level like around 2V output, to start with (or check your pre's input sensitivity spec).

 

But then again adding a pre to the path (add more electronics to your signal path) you might lose all the things you gained like your earlier comments:

 

"I'm frankly stunned that it's taken me three years to try the Mojo as a pre.. Clarity, separation, depth, soundstage, resolution, highs/lows they're all better. Absolutely chuffed with the result. Amazing a pre could colour the sound so much. Now I'm keen to try a really good pre!"

 

No harm in trying and deciding with your ears though.

Edited by rand129678
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19 hours ago, Crabsticks said:

Thanks again all. I have been flat out listening and can confirm it's quite the revelation. I'm frankly stunned that it's taken me three years to try the Mojo as a pre..

 

Clarity, separation, depth, soundstage, resolution, highs/lows they're all better. Absolutely chuffed with the result. Amazing a pre could colour the sound so much. Now I'm keen to try a really good pre!

 

Another question. Say I did buy/borrow a pre, how does the Mojo know to act as just a DAC and not a pre? So if I'm going RCA into a dedicated pre from the Mojo, how does it know to only perform the DAC function? If that makes sense.

 

The Chord DACs are completely unconventional in how they are designed. While most DACs involve a series of chips for input feeding a DAC chip, then an amplification stage, Chord DACs are software-programmed onto an FPGA which outputs (from memory) a 5-bit PWM signal into a series of transistors for final conversion and output. The use of a powerful FPGA allows for much more powerful and accurate processing of the signal. While a conventional DAC might do 8x or 16x oversampling, the Chord DACs do 2048x oversampling! With a special digital filter that has been researched over decades, digital volume control can be implemented in the digital domain without losing the sense of depth and nuances in the music. 

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I use a Chord Hugo TT2 DAC as a pre and can highly recommend not having anything else in the signal chain.

Custom music server to Chord Hugo TT2 then Cyrus Signature X200 power amps.

Lovely.

I did have to set the DAC to the "low gain" setting which has a max of 3.3 V out.

Not sure if the Mojo is the same....

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Great information on the 

On 18/11/2020 at 6:41 PM, rand129678 said:

 

There's a spreadsheet somewhere on Head-Fi Forum but after you set to 'line level' mode (3V), here are the output voltages with each volume button click down from 3V mode:

 

0 clicks down = 3 Vrms
1 click down = 2.67 Vrms  
2 clicks down = 2.38 Vrms 
3 clicks down = 2.1 Vrms 
4 clicks down = 1.9 Vrms 

 

Thanks for this information, I set the line level mode on the Mojo then knocked it down 20 clicks. This gives a realistic listening volume (is this .2 Vrms?) 

 

Not clear on how this is different from just turning the Mojo on and clicking the volume up or down as needed instead of activating line level mode? If it is different?

44 minutes ago, Eternaloptimist said:

I use a Chord Hugo TT2 DAC as a pre and can highly recommend not having anything else in the signal chain.

Custom music server to Chord Hugo TT2 then Cyrus Signature X200 power amps.

Lovely.

I did have to set the DAC to the "low gain" setting which has a max of 3.3 V out.

Not sure if the Mojo is the same....

 

Sounds awesome, would like to listen to a DAC of that quality with Cyrus amps. My first integrated was a Cyrus, and I have had many of their components over the years.

1 hour ago, Currawong said:

 

The Chord DACs are completely unconventional in how they are designed.

 

Thanks Currawong. I know a guy that will understand that and probably get quite excited by it..

 

@stereo coffee

"Given amplifiers are tasked to amplify their input and nothing else ,  ideally  source level RMS, should then match to power amp RMS sensitivity, so all that is needed in between, is simple attenuation, exampled by the specification attached."

 

I think my DM10's are 500mV analogue input sensitivity. So does that mean I need to try and match that output from the Mojo? As I mention above, I have the Mojo set line level and 20 clicks down from 0, which I think is 200mV. Although, I'm learning as I go here so might be wrong about that!

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29 minutes ago, Crabsticks said:

Not clear on how this is different from just turning the Mojo on and clicking the volume up or down as needed instead of activating line level mode? If it is different?

 

No difference. I only know the voltages clicking down from the 3V position, because someone calculated/shared on Head-Fi forum.

 

I think if you search the massive Mojo thread over there for "spreadsheet" it may come up. It's been a while since I looked at it.

 

 

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8 hours ago, Crabsticks said:

Great information on the 

 

Thanks for this information, I set the line level mode on the Mojo then knocked it down 20 clicks. This gives a realistic listening volume (is this .2 Vrms?) 

 

Not clear on how this is different from just turning the Mojo on and clicking the volume up or down as needed instead of activating line level mode? If it is different?

 

Sounds awesome, would like to listen to a DAC of that quality with Cyrus amps. My first integrated was a Cyrus, and I have had many of their components over the years.

 

Thanks Currawong. I know a guy that will understand that and probably get quite excited by it..

 

@stereo coffee

"Given amplifiers are tasked to amplify their input and nothing else ,  ideally  source level RMS, should then match to power amp RMS sensitivity, so all that is needed in between, is simple attenuation, exampled by the specification attached."

 

I think my DM10's are 500mV analogue input sensitivity. So does that mean I need to try and match that output from the Mojo? As I mention above, I have the Mojo set line level and 20 clicks down from 0, which I think is 200mV. Although, I'm learning as I go here so might be wrong about that!

Hi Dan

So other readers are not lost here, the chord Mojo is a headphone amplifier, so using it as a DAC is quite OK, it may though be problematic as a preamp, as its level may well exceed the sensitivity of your AVI DM10 with analogue input. As you say its hard to exactly discern the level you need.

 

How does it sound to you ? and does the level you use,  change the sound quality - that is without over- driving the AV DM10's  ?

 

Having better control of volume  and Less, with regard to complexity of attenuation,   between your source and speakers, I suspect will be a lot lot  more. 

 

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On 20/11/2020 at 4:35 AM, stereo coffee said:

How does it sound to you ? and does the level you use,  change the sound quality - that is without over- driving the AV DM10's?

 

 

It sounds good. Really good. I thought the system sounded good before, but now I don't feel like I'm gearing the system at all, more like I'm hearing the music a lot more. Probably a clichè, but instead of me listening for technical perfection of the hi-fi I seem to be listening to much more of the true sounds of the musicians.

 

I can detect no interference, distortion or noise at the volume levels I've been using. In terms of clicks down from line out mode (3V), I'm at 20 clicks down. I think that's 200mVrms. But I am prepared to be corrected..

 

I'll send you an email regarding one of your pre-amps and a couple of questions I have. 

 

Also, does anybody know where I can purchase a Quad 306? And what do I need to look out for in terms of potential faults. I'm not familiar with the history of this amp so If anybody has information on the differing models/year release of the amp I'd be grateful.

 

Thanks again.

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I have a similar question, so I might as well use the same discussion thread to ask you knowledgeable folks.

I have a PrimaLuna Premium Prologue preamp and a Chord Qutest DAC. The PL pre-amp has the following specs:

 

Input Impedance .................................................................................................................................................................................................................. 220 kOhm
Input Sensitivity ............................................................................................................................................................ 220 mV for full output power

 

What does it mean by "220 mV for full output power"?  Is it the preferred input voltage from a source?

I have a Chord Qutest DAC that can output 1V, 2V or 3V RMS.  Unlike the Chord Mojo I can't adjust the output volume of the Qutest. Which setting is the right match for the input sensitivity of the preamp?  I tried all 3 settings and it seems that 2V sounds best. It's trial and error but I'd like to understand why.

 

Thank you in advance.

Tony

 

 

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