[GuiltyRocker]

Got my M Scaler today, bought off ebay and in immaculate condition with all accessories and packaging. Hooked it up and OMG!
=8-0
Running dual BNC into Qutest everything sounds so live and organic. I thought the Qutest was good but this is just next level. Instruments sound so solid and tangible, occupying real space. A lot of music just sounds so different too, in a totally good way. I can distinguish between instruments with real clarity. I feel like I am hearing things in 3D.

Rest of my system is WiiM Pro streamer, Cambridge CXC CD transport, 1992 vintage Naim NAC72 / NAP140 pre-power amps and Fyne F501SP speakers. I thought the amps might be a limitation but clearly not.

The impact is on all music types I have tried, mainly classical and jazz, but also folk and some electronic.

It will take me a year to pay for it, but so far I think it will be worth it.

Edit: Oh, and I was forgetting what forum I am on - Naim Headline headphone amp and Sennheiser HD600 headphones.

That is exactly what I experienced when I plugged the M Scaler into the Qutest. Another positive effect was the complete reduction of Sibilance in all tracks, especially the ones that had it the most and were bright, the sibilance was gone! Rob Watts is a master of digital, I love the M Scaler.

 

[Reactcore]

The impact is on all music types I have tried, mainly classical and jazz, but also folk and some electronic.

Welcome to the club!
Just how my Mscaler journey started too.. with Qutest.
It’s a fine combo as Qutest is optimised due to being released after HMS.

Be shure to play from bitperfect sources without any software DSP or EQ.
Btw one can drive headphones straight out of Qutest too for maximum transparency. But software volume is then needed.

 

[OneOfTheLastMen]

Welcome to the club!
Just how my Mscaler journey started too.. with Qutest.
It’s a fine combo as Qutest is optimised due to being released after HMS.

Be shure to play from bitperfect sources without any software DSP or EQ.
Btw one can drive headphones straight out of Qutest too for maximum transparency. But software volume is then needed.

I stream mainly from the WiiM native implementation of Amazon Music Unlimited, which is all uncompressed FLAC and at least 16/44.1 but quite often 24/48 or better. I have disabled EQ and digital volume on the WiiM to make the binary as pristine as possible. The CD transport also has no EQ or volume so not a problem there. Both digital inputs are optical, as recommended by Rob.

 

[Meridian7]

...Be shure to play from bitperfect sources without any software DSP or EQ.

My thoughts too. For Roon dsp it is argued that one can't possibly hear difference so it must be psy BS iterferring. Still, I prefer it untouched nonetheless.

 

[ecwl]

Got my M Scaler today, bought off ebay and in immaculate condition with all accessories and packaging. Hooked it up and OMG!

Rest of my system is WiiM Pro streamer, Cambridge CXC CD transport, 1992 vintage Naim NAC72 / NAP140 pre-power amps and Fyne F501SP speakers. I thought the amps might be a limitation but clearly not.

Edit: Oh, and I was forgetting what forum I am on - Naim Headline headphone amp and Sennheiser HD600 headphones.

Congrats on the M-Scaler. One thing I was thinking reading about your Naim Headline headphone amp and NAC72 preamp, I wonder if they’re meant for 1V RCA input, rather than 2V and unlikely to be 3V. The problem is that there is no documentation to tell you if you set your Qutest output to 2V or 3V, whether the Headline/NAC72 would clip. Sometimes it might not and you’re fine. But sometimes, they might even if you turn the volume way down which would distort the sound. So you may want to experiment with Qutest’s output voltage if you haven’t already.

Now if you have the Qutest set to 2V and you add the M-Scaler, because the M-Scaler attenuates by -2.73dB, you’ll be getting 1.457V which might reduce the clipping if it’s an issue. Of course, with the Qutest at 1V, you’ll get about 0.73V. But then that’s what the volume control is for.

 

[OneOfTheLastMen]

Congrats on the M-Scaler. One thing I was thinking reading about your Naim Headline headphone amp and NAC72 preamp, I wonder if they’re meant for 1V RCA input, rather than 2V and unlikely to be 3V. The problem is that there is no documentation to tell you if you set your Qutest output to 2V or 3V, whether the Headline/NAC72 would clip. Sometimes it might not and you’re fine. But sometimes, they might even if you turn the volume way down which would distort the sound. So you may want to experiment with Qutest’s output voltage if you haven’t already.

Now if you have the Qutest set to 2V and you add the M-Scaler, because the M-Scaler attenuates by -2.73dB, you’ll be getting 1.457V which might reduce the clipping if it’s an issue. Of course, with the Qutest at 1V, you’ll get about 0.73V. But then that’s what the volume control is for.

Thanks for that, very interesting! I have the Qutest set to 2V and did notice that with the M Scaler it appeared quieter and that I had to turn up the volume relative to the Qutest on its own. Now I know why.

I'm not sure what impact the clipping would have on the sound but, just to be safe, I will change the output of the Qutest to 1v.
By the way, when I got the Qutest I tried finding information on what output voltage I should use into the Naim amp and couldn't find anything. Where did you see that?

 

[ecwl]

Thanks for that, very interesting! I have the Qutest set to 2V and did notice that with the M Scaler it appeared quieter and that I had to turn up the volume relative to the Qutest on its own. Now I know why.

I'm not sure what impact the clipping would have on the sound but, just to be safe, I will change the output of the Qutest to 1v.
By the way, when I got the Qutest I tried finding information on what output voltage I should use into the Naim amp and couldn't find anything. Where did you see that?

In the headline manual, the maximum output voltage was 3.7 V and the gain is 13.56 dB. This would suggest that the expected input voltage is 1V. But that said it doesn’t necessarily mean that your amp is going to clip if you feed it 2 V. You would have to listen or ask Naim to find out if it clips or not.

 

[OneOfTheLastMen]

Trying to get my head round all this. The output voltage from the DAC seems to be the maximum voltage (correct me if I am wrong). No idea what the average will therefore be at the 1V setting, or how often it will get close to 1V.

I have found the old instructions for the NAC-72 and it states the input sensitivity for the line level inputs is 75mV, which is very high (lower the number, higher the sensitivity). Most modern amps have a sensitivity of around 400mV apparently. That means at 75mV you can turn the volume control to 100% without it clipping. However, that is only 0.075V, or 7.5% of the maximum that the DAC could output at the 1V setting. That would seem to imply that I cannot use more than 7.5% of the volume control if I want to avoid output voltage clipping.

That seems to be at odds with how I actually use the volume control. At the 2V output from the Qutest I could happily leave the volume control at the 25% position (9 o'clock) for a decent sound level with no apparent clipping. That is assuming that the volume control is linear of course. All very confusing!

 

[ecwl]

Trying to get my head round all this. The output voltage from the DAC seems to be the maximum voltage (correct me if I am wrong). No idea what the average will therefore be at the 1V setting, or how often it will get close to 1V.

I have found the old instructions for the NAC-72 and it states the input sensitivity for the line level inputs is 75mV, which is very high (lower the number, higher the sensitivity). Most modern amps have a sensitivity of around 400mV apparently. That means at 75mV you can turn the volume control to 100% without it clipping. However, that is only 0.075V, or 7.5% of the maximum that the DAC could output at the 1V setting. That would seem to imply that I cannot use more than 7.5% of the volume control if I want to avoid output voltage clipping.

That seems to be at odds with how I actually use the volume control. At the 2V output from the Qutest I could happily leave the volume control at the 25% position (9 o'clock) for a decent sound level with no apparent clipping. That is assuming that the volume control is linear of course. All very confusing!

For me, there is not enough info to say whether NAC-72 would clip.

But I think it's easier to comment on the Headline since its input sensitivity is 1V.

Basically, there are two ways how you can clip.
The most obvious way is that if you have the Qutest output at 2V and decide to crank up the volume to max and the recorded digital music actually uses the maximum volume at times. Since there is no way to go beyond 3.78V, for sure your Qutest would clip when the music is playing its loudest notes. This is true whenever your volume control is cranked too high and the music goes beyond 3.78V.

But the other way some preamps can clip is that even if you have the volume dial set to no gain (so fairly low volume setting let's say), and you feed it a 2V signal and its input sensitivity is 1V, the preamp is not capable of just passing the 2V through. It would have trouble handling all the input signals between 1V-2V even though you have zero intention of amplifying that signal. As a result, all the music above 1V would clip.

Ultimately, it comes down to the circuit design. Which is why only the manufacturer can tell you whether at 2V or 3V whether the music would clip through your preamp.

From the sounds of it, Headline doesn't clip when you feed it 2V signal. If that's the case, you can even try feeding it 3V and turn down the volume of Headline further and see if the music sounds distorted in the loudest passages. If it doesn't, then the Headline probably doesn't clip at 3V either. Then, it's really up to what sounds the best to you. Coming from the Qutest, 3V would have better SNR than 2V than 1V. However, your volume control on Headline would probably have more distortions and slight left-right imbalance at different volume levels. So it's best to find the optimal positions in the dial for the music you listen to and then set the Qutest voltage based on what the Headline needs for that volume control position if you want optimal sound quality. Assuming the preamp doesn't clip.

 

[OneOfTheLastMen]

Thanks for that. I have found a bit more information since I wrote the last post.

The input sensitivity is 75mV and the maximum output voltage to the power-amp is 0.775V when the volume control is at 100%, so the maximum gain is about x10, although confusingly I have seen it quoted elsewhere as sometimes x13 and sometimes x12. Your guess is as good as mine!

Tape out (which is where the Headline connects) has no separate level control, and the specification states the maximum output is also 0.775V [misread, see edit].

As a point of interest, I have replacement line out boards in the Naim from Kit Ryan (Ryan Sound Labs). These have a jumper which can adjust gain to either x13, x4 or x1.3. I currently have it at x4, which presumably means the input sensitivity is 0.775V divided by 4 = ~ 200mV. That would explain why the volume control is still useable at 2V from the Qutest!

EDIT: I think I have finally found the answer, and the reason I probably don't have to worry too much about the Naim amp's high input sensitivity. The Naim manual states that there is: "Overload margin, on all inputs at all audio frequencies 40db", which is a multiple of x100 in voltage terms. With an input sensitivity of 75mV that implies a maximum 7.5V before the input overloads. I have read elsewhere that Naim pre-amps can cope with 7V at the input without a problem, and I presume this is where that figure comes from. Of course, that is around x10 the output voltage, so you would barely be able to move the volume control off the zero mark at 7.5V input. However, it also means it could cope quite happily with the Qutest at 3V as well, but again that would give you very little range on the volume control.

I misread the tape output voltage, which is 75mV. Presumably there is attenuation in the circuit somewhere to drop it to that level. The input sensitivity of the Headline is actually 820mV, so no chance of it overloading.

 

[User9876]

Got my M Scaler today, bought off ebay and in immaculate condition with all accessories and packaging. Hooked it up and OMG!
=8-0
Running dual BNC into Qutest everything sounds so live and organic. I thought the Qutest was good but this is just next level. Instruments sound so solid and tangible, occupying real space. A lot of music just sounds so different too, in a totally good way. I can distinguish between instruments with real clarity. I feel like I am hearing things in 3D.

Rest of my system is WiiM Pro streamer, Cambridge CXC CD transport, 1992 vintage Naim NAC72 / NAP140 pre-power amps and Fyne F501SP speakers. I thought the amps might be a limitation but clearly not.

The impact is on all music types I have tried, mainly classical and jazz, but also folk and some electronic.

It will take me a year to pay for it, but so far I think it will be worth it.

Edit: Oh, and I was forgetting what forum I am on - Naim Headline headphone amp and Sennheiser HD600 headphones.

Thanks for posting about this, I just went on ebay and found a used mscaler myself for a good price from my local Chord dealer with six months warranty and at a good price so I'll collect it tomorrow.

 

[OneOfTheLastMen]

I think I have finally found the answer, and the reason I probably don't have to worry too much about the Naim amp's high input sensitivity. The Naim manual states that there is: "Overload margin, on all inputs at all audio frequencies 40db", which is a multiple of x100 in voltage terms. With an input sensitivity of 75mV that implies a maximum 7.5V before the input overloads. I have read elsewhere that Naim pre-amps can cope with 7V at the input without a problem, and I presume this is where that figure comes from. Of course, that is around x10 the output voltage, so you would barely be able to move the volume control off the zero mark at 7.5V input. However, it also means it could cope quite happily with the Qutest at 3V as well, but again that would give you very little range on the volume control.

I misread the tape output voltage, which is 75mV. Presumably there is attenuation in the circuit somewhere to drop it to that level. The input sensitivity of the Headline is actually 820mV, so no chance of it overloading.

I put the questions to Kit Ryan, who very kindly responded with the figures from his modified version of the Naim line out boards that produce the signal going to the power amp. At default settings the figures are very similar to the stock Naim setup.

The maximum output from the pre-amp towards the power-amp is 5V before the pre-amp will clip. The input sensitivity of my power amp is 1V, so the power-amp will clip well before the pre-amp does. Most power-amp sensitivities are in the 1-2V range so the same will apply to any make of power-amp.

The inputs can accept any voltage (up to around 7.5V), but the stock pre-amp circuit will apply a gain of x13.3 when the volume control is turned right round to maximum. Where the "input sensitivity" figure comes from is the output voltage of 1V (to match the power-amp sensitivity) divided by the gain multiplier of x13.3, which equals 75mV (0.075V). Because of the high gain multiplier, if you put a higher voltage than this at the input, and then turn the volume up full, you could drive the power-amp into clipping. The pre-amp will be fine.

Very usefully, Kit Ryan's replacement boards have three jumper positions to modify the gain multiplier - either x13.3 (stock), x4 and x1.3. So the input sensitivities at each jumper position are as follows:
Max = 1V/13.3 = 0.075V
Mid = 1V/4 = 0.25V
Min = 1V/1.3 = 0.77V

At the moment I have the gain jumper at x4, which means input sensitivity is 0.250V. I also have the Qutest set at 2V, so I cannot use more than 12.5% (250mV/2V) of the volume control range before there is a danger of the power-amp clipping. So I probably need to reduce the gain multiplier, or Qutest voltage, or both to give me more useable range from the volume control. My options are:
x1.3 at 2V = 0.77V / 2V = 38.5%
x4 at 1V = 0.25V / 1V = 25%
x1.3 at 1V = 0.77V / 1V = 77%

I need to give that some further thought. On the assumption that the M Scaler reduces the 1V output from the Qutest to 0.73V, at the x1.3 jumper setting I could use almost 100% of the volume control rotation before the power-amp is in any danger of clipping.

EDIT: Re the tape out, it is buffered, but the gain is effectively x1 the input voltage. So if the input from the Qutest is 2V then that is what goes through to the Headline. The Headline's maximum output voltage to the headphone socket is 3.7V, and the gain factor is x4.73 (13.5dB), implying an input sensitivity at maximum volume of 0.63V. That means I could use 86% of the Headline's volume control range without it clipping if I use the Qutest at 1V, being an actual 0.73V as modified by the M Scaler.

 

[ecwl]

I put the questions to Kit Ryan, who very kindly responded with the figures from his modified version of the Naim line out boards that produce the signal going to the power amp. At default settings the figures are very similar to the stock Naim setup.

The maximum output from the pre-amp towards the power-amp is 5V before the pre-amp will clip. The input sensitivity of my power amp is 1V, so the power-amp will clip well before the pre-amp does. Most power-amp sensitivities are in the 1-2V range so the same will apply to any make of power-amp.

The inputs can accept any voltage (up to around 7.5V), but the stock pre-amp circuit will apply a gain of x13.3 when the volume control is turned right round to maximum. Where the "input sensitivity" figure comes from is the output voltage of 1V (to match the power-amp sensitivity) divided by the gain multiplier of x13.3, which equals 75mV (0.075V). Because of the high gain multiplier, if you put a higher voltage than this at the input, and then turn the volume up full, you could drive the power-amp into clipping. The pre-amp will be fine.

Very usefully, Kit Ryan's replacement boards have three jumper positions to modify the gain multiplier - either x13.3 (stock), x4 and x1.3. So the input sensitivities at each jumper position are as follows:
Max = 1V/13.3 = 0.075V
Mid = 1V/4 = 0.25V
Min = 1V/1.3 = 0.77V

At the moment I have the gain jumper at x4, which means input sensitivity is 0.250V. I also have the Qutest set at 2V, so I cannot use more than 12.5% (250mV/2V) of the volume control range before there is a danger of the power-amp clipping. So I probably need to reduce the gain multiplier, or Qutest voltage, or both to give me more useable range from the volume control. My options are:
x1.3 at 2V = 0.77V / 2V = 38.5%
x4 at 1V = 0.25V / 1V = 25%
x1.3 at 1V = 0.77V / 1V = 77%

I need to give that some further thought. On the assumption that the M Scaler reduces the 1V output from the Qutest to 0.73V, at the x1.3 jumper setting I could use almost 100% of the volume control rotation before the power-amp is in any danger of clipping.

That is fantastic information to know.

But I think about the situation totally differently. It sounds like Naim pre-amps would never clip any input signal. So you can easily set the Qutest to 3V.

So unless you (or a child/pet/cleaning staff) really crank up the volume, you won't clip or blow up the speakers/headphones.

Hence, the ultimate sound quality would be mostly dependent on your volume knob at different settings as different settings tend to have different levels of left-right matching, SNR, and linearity. Meaning that for some volume knobs, the sound is nicest between 8-10 o'clock, others it could be 2-4 o'clock. But most volume knobs are most linear when the volume is around 10-2 o'clock.

I personally would set the Qutest to 3V, Kit Ryan board jumper to 1.3x gain first if I were in your shoes. And see where your volume knob is and how it sounds.

 

[OneOfTheLastMen]

That is fantastic information to know.

But I think about the situation totally differently. It sounds like Naim pre-amps would never clip any input signal. So you can easily set the Qutest to 3V.

So unless you (or a child/pet/cleaning staff) really crank up the volume, you won't clip or blow up the speakers/headphones.

Hence, the ultimate sound quality would be mostly dependent on your volume knob at different settings as different settings tend to have different levels of left-right matching, SNR, and linearity. Meaning that for some volume knobs, the sound is nicest between 8-10 o'clock, others it could be 2-4 o'clock. But most volume knobs are most linear when the volume is around 10-2 o'clock.

I personally would set the Qutest to 3V, Kit Ryan board jumper to 1.3x gain first if I were in your shoes. And see where your volume knob is and how it sounds.

Fair point, and one to consider. 3V at x1.3 is the same range on the volume control as 1V at x4 being around 25% (0.77V / 3V and 0.25V / 1V). The latter setting is what I have it at right now. I do also have to consider that I have a turntable with an MC cartridge going into the same pre-amp, and I don't think a gain of x1.3 would cut it for a phono input, but I know I can get away with x4 as I have listened to many LPs at that level, usually with the volume control at 12:00 - 2:00 for "very loud".

Just listened to the final movement of Beethoven's 9th (The Choral) from CD at a volume that might annoy my neighbours. The Qutest / M Scaler was set to 1V (0.73V actual) and the gain jumper set to x4. The volume control was at the 12:00 position, so pretty well ideal if you are right about volume controls. It also sounded fantastic

IIRC, I have read a post by Rob Watts somewhere that said there was no perceptible difference in sound quality between 1V and 3V from the Qutest. After all, the TT2 has a full digital volume control, and I have heard nobody say that its sound quality is compromised at lower volume (output voltage). If anybody can do a digital volume control properly it will be Rob!

I have just read on Kit Ryan's website that he is retiring, and his upgrade boards will no longer be available. A great loss for owners of the early Naim pre-amps with slot in circuit boards, but bearing in mind they are all now at least 30 years old, it is a pretty niche sector to be in so I don't blame him for putting his feet up!

(Edited for lots of drafting errors and news from Kit Ryan)

 

[rwelles]

I'm looking to add an M-Scaler to my TT2. Any recommendations for BNC interconnects?